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Sample records for optical communication based

  1. Optical bidirectional beacon based visible light communications.

    PubMed

    Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon Ho

    2015-10-01

    In an indoor bidirectional visible light communications (VLC), a line-of-sight (LOS) transmission plays a major role in obtaining adequate performance of a VLC system. Signals are often obstructed in the LOS transmission path, causing an effect called optical shadowing. In the absence of LOS, the performance of the VLC system degrades significantly and, in particular, at uplink transmission this degradation becomes severe due to design constraints and limited power at uplink devices. In this paper, a novel concept and design of an optical bidirectional beacon (OBB) is presented as an efficient model to counter the performance degradation in a non-line-of-sight (NLOS) VLC system. OBB is an independent operating bidirectional transceiver unit installed on walls, composed of red, green, and blue (RGB) light emitting diodes (LEDs), photodetectors (PDs) and color filters. OBB improves the coverage area in the form of providing additional or alternate paths for transmission and enhances the performance of the VLC system in terms of bit error rate (BER). To verify the effectiveness of the proposed system, simulations were carried out under optical shadowing conditions at various locations in an indoor environment. The simulation results and analysis show that the implementation of OBB improves the performance of the VLC system significantly, especially when the LOS bidirectional transmission paths are completely or partially obstructed. PMID:26480168

  2. Optical Communications

    ERIC Educational Resources Information Center

    Young, Matt

    1973-01-01

    Describes the characteristics and operational problems of optical waveguides, and concludes that the wide use of optical communications can be expected if difficulties in commercial production of components can be eliminated. (CC)

  3. All-optical virtual private network and ONUs communication in optical OFDM-based PON system.

    PubMed

    Zhang, Chongfu; Huang, Jian; Chen, Chen; Qiu, Kun

    2011-11-21

    We propose and demonstrate a novel scheme, which enables all-optical virtual private network (VPN) and all-optical optical network units (ONUs) inter-communications in optical orthogonal frequency-division multiplexing-based passive optical network (OFDM-PON) system using the subcarrier bands allocation for the first time (to our knowledge). We consider the intra-VPN and inter-VPN communications which correspond to two different cases: VPN communication among ONUs in one group and in different groups. The proposed scheme can provide the enhanced security and a more flexible configuration for VPN users compared to the VPN in WDM-PON or TDM-PON systems. The all-optical VPN and inter-ONU communications at 10-Gbit/s with 16 quadrature amplitude modulation (16 QAM) for the proposed optical OFDM-PON system are demonstrated. These results verify that the proposed scheme is feasible. PMID:22109510

  4. Space Station-based deep-space optical communication experiments

    NASA Technical Reports Server (NTRS)

    Chen, Chien-Chung; Schwartz, Jon A.

    1988-01-01

    A series of three experiments proposed for advanced optical deep-space communications is described. These proposed experiments would be carried out aboard the Space Station to test and evaluate the capability of optical instruments to conduct data communication and spacecraft navigation for deep-space missions. Techniques for effective data communication, precision spacecraft ranging, and accurate angular measurements will be developed and evaluated in a spaceborne environment.

  5. OPALS: A COTS-based Tech Demo of Optical Communications

    NASA Technical Reports Server (NTRS)

    Oaida, Bogdan

    2012-01-01

    I. Objective: Deliver video from ISS to optical ground terminal via an optical communications link. a) JPL Phaeton/Early Career Hire (ECH) training project. b) Implemented as Class-D payload. c) Downlink at approx.30Mb/s. II. Flight System a) Optical Head Beacon Acquisition Camera. Downlink Transmitter. 2-axis Gimbal. b) Sealed Container Laser Avionics Power distribution Digital I/O board III. Implementation: a) Ground Station - Optical Communications Telescope Laboratory at Table Mountain Facility b) Flight System mounted to ISS FRAM as standard I/F. Attached externally on Express Logistics Carrier.

  6. Channel capacity study of underwater wireless optical communications links based on Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Li, Jing; Ma, Yong; Zhou, Qunqun; Zhou, Bo; Wang, Hongyuan

    2012-01-01

    Channel capacity of ocean water is limited by propagation distance and optical properties. Previous studies on this problem are based on water-tank experiments with different amounts of Maalox antacid. However, propagation distance is limited by the experimental set-up and the optical properties are different from ocean water. Therefore, the experiment result is not accurate for the physical design of underwater wireless communications links. This letter developed a Monte Carlo model to study channel capacity of underwater optical communications. Moreover, this model can flexibly configure various parameters of transmitter, receiver and channel, and is suitable for physical underwater optical communications links design.

  7. Performance analysis of fiber-based free-space optical communications with coherent detection spatial diversity.

    PubMed

    Li, Kangning; Ma, Jing; Tan, Liying; Yu, Siyuan; Zhai, Chao

    2016-06-10

    The performances of fiber-based free-space optical (FSO) communications over gamma-gamma distributed turbulence are studied for multiple aperture receiver systems. The equal gain combining (EGC) technique is considered as a practical scheme to mitigate the atmospheric turbulence. Bit error rate (BER) performances for binary-phase-shift-keying-modulated coherent detection fiber-based free-space optical communications are derived and analyzed for EGC diversity receptions through an approximation method. To show the net diversity gain of a multiple aperture receiver system, BER performances of EGC are compared with a single monolithic aperture receiver system with the same total aperture area (same average total incident optical power on the aperture surface) for fiber-based free-space optical communications. The analytical results are verified by Monte Carlo simulations. System performances are also compared for EGC diversity coherent FSO communications with or without considering fiber-coupling efficiencies. PMID:27409022

  8. Scheduling algorithm for data relay satellite optical communication based on artificial intelligent optimization

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-hu; Zhao, Jing; Zhao, Shang-hong; Li, Yong-jun; Wang, Xiang; Dong, Yi; Dong, Chen

    2013-08-01

    Optical satellite communication with the advantages of broadband, large capacity and low power consuming broke the bottleneck of the traditional microwave satellite communication. The formation of the Space-based Information System with the technology of high performance optical inter-satellite communication and the realization of global seamless coverage and mobile terminal accessing are the necessary trend of the development of optical satellite communication. Considering the resources, missions and restraints of Data Relay Satellite Optical Communication System, a model of optical communication resources scheduling is established and a scheduling algorithm based on artificial intelligent optimization is put forwarded. According to the multi-relay-satellite, multi-user-satellite, multi-optical-antenna and multi-mission with several priority weights, the resources are scheduled reasonable by the operation: "Ascertain Current Mission Scheduling Time" and "Refresh Latter Mission Time-Window". The priority weight is considered as the parameter of the fitness function and the scheduling project is optimized by the Genetic Algorithm. The simulation scenarios including 3 relay satellites with 6 optical antennas, 12 user satellites and 30 missions, the simulation result reveals that the algorithm obtain satisfactory results in both efficiency and performance and resources scheduling model and the optimization algorithm are suitable in multi-relay-satellite, multi-user-satellite, and multi-optical-antenna recourses scheduling problem.

  9. Technology, Data Bases and System Analysis for Space-to-Ground Optical Communications

    NASA Technical Reports Server (NTRS)

    Lesh, James

    1995-01-01

    Optical communications is becoming an ever-increasingly important option for designers of space-to- ground communications links, whether it be for government or commercial applications. In this paper the technology being developed by NASA for use in space-to-ground optical communications is presented. Next, a program which is collecting a long term data base of atmospheric visibility statistics for optical propagation through the atmosphere will be described. Finally, a methodology for utilizing the statistics of the atmospheric data base in the analysis of space-to-ground links will be presented. This methodology takes into account the effects of station availability, is useful when comparing optical communications with microwave systems, and provides a rationale establishing the recommended link margin.

  10. Generation of spectral-encoded signals in noncoherent optical communication systems based on acousto-optic multiwavelength filters

    NASA Astrophysics Data System (ADS)

    Proklov, V. V.; Byshevski-Konopko, O. A.; Filatov, A. L.

    2015-10-01

    New acousto-optical (AO) methods and devices necessary for the creation of noncoherent optical code division multiple access (O-CDMA) systems are considered. Based on an AO multiwavelength filter, an original device generating spectral-encoded signals for O-CDMA systems with optimum WDM has been created and studied. It is shown that modern AO technology is capable of surmounting difficulties that previously hindered the transition of optical communication systems to CDMA data transmission.

  11. A Combined Radio and Underwater Wireless Optical Communication System based on Buoys

    NASA Astrophysics Data System (ADS)

    Song, Yuhang; Tong, Zheng; Cong, Bo; Yu, Xiangyu; Kong, Meiwei; Lin, Aobo

    2016-02-01

    We propose a system of combining radio and underwater wireless optical communication based on buoys for real-time image and video transmission between underwater vehicles and the base station on the shore. We analysis how the BER performance is affected by the link distance and the deflection angle of the light source using Monte Carlo simulation.

  12. Optical laser cross-link in space-based systems used for satellite communications

    NASA Astrophysics Data System (ADS)

    Panahi, Allen; Kazemi, Alex A.

    2010-04-01

    Building high speed communications network using optical links in space has proven to be an extremely complicated task and many such schemes were tried without success in the past. However in the last few years, there has been impressive progress made to bring the concept to fruition in civilian and government non-classified projects. Space-based optical communications using satellites in low earth orbit (LEO) and Geo-synchronous orbits (GEO) hold great promise for the proposed Internet in the Sky network of the future. Laser Communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity. This paper will focus on the requirements of the space-based lasers and optics used for beam forming, as well as receiver antenna gain and detectors used in free space communications. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. Also discussed are the critical parameters in the transmitter, channel, receiver, and link budget that are employed in successful inter-satellite communications system.

  13. Design of oil pipeline leak detection and communication system based on optical fiber technology

    NASA Astrophysics Data System (ADS)

    Tu, Yaqing; Chen, Huabo

    1999-08-01

    The integrity of oil pipeline is always a major concern of operators. Pipeline leak not only leads to loss of oil, but pollutes environment. A new pipeline leak detection and communication system based on optical fiber technology to ensure the pipeline reliability is presented. Combined direct leak detection method with an indirect one, the system will greatly reduce the rate of false alarm. According, to the practical features of oil pipeline,the pipeline communication system is designed employing the state-of-the-art optic fiber communication technology. The system has such feature as high location accuracy of leak detection, good real-time characteristic, etc. which overcomes the disadvantages of traditional leak detection methods and communication system effectively.

  14. Indoor location estimation with optical-based orthogonal frequency division multiplexing communications

    NASA Astrophysics Data System (ADS)

    Aminikashani, Mohammadreza; Gu, Wenjun; Kavehrad, Mohsen

    2016-05-01

    Visible light communication (VLC) using light-emitting diodes has been gaining increasing attention in recent years as it is appealing for a wide range of applications such as indoor positioning. Orthogonal frequency division multiplexing (OFDM) has been applied to indoor wireless optical communications in order to mitigate the effect of multipath distortion of the optical channel as well as increasing the data rate. An OFDM VLC system is proposed, which can be utilized for both communications and indoor positioning. A positioning algorithm based on power attenuation is used to estimate the receiver coordinates. We further calculate the positioning errors in all the locations of a room and compare them with those using single-carrier modulation schemes, i.e., on-off keying modulation. We demonstrate that our proposed OFDM positioning system outperforms by 74% its conventional counterpart. Finally, we investigate the impact of different system parameters on the positioning accuracy of the proposed OFDM VLC system.

  15. Optical satellite communications in Europe

    NASA Astrophysics Data System (ADS)

    Sodnik, Zoran; Lutz, Hanspeter; Furch, Bernhard; Meyer, Rolf

    2010-02-01

    This paper describes optical satellite communication activities based on technology developments, which started in Europe more than 30 years ago and led in 2001 to the world-first optical inter-satellite communication link experiment (SILEX). SILEX proved that optical communication technologies can be reliably mastered in space and in 2006 the Japanese Space Agency (JAXA) joined the optical inter-satellite experiment from their own satellite. Since 2008 the German Space Agency (DLR) is operating an inter-satellite link between the NFIRE and TerraSAR-X satellites based on a second generation of laser communication technology, which will be used for the new European Data Relay Satellite (EDRS) system to be deployed in 2013.

  16. Investigation on the bit error rate performance of 40Gb/s space optical communication system based on BPSK scheme

    NASA Astrophysics Data System (ADS)

    Li, Mi; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Liu, Jia; Tu, Guojie

    2015-08-01

    Space optical communication technique is attracting increasingly more attention because it owns advantages such as high security and great communication quality compared with microwave communication. As the space optical communication develops, people have already achieved the communication at data rate of Gb/s currently. The next generation for space optical system have goal of the higher data rate of 40Gb/s. However, the traditional optical communication system cannot satisfy it when the data rate of system is at such high extent. This paper will introduce ground optical communication system of 40Gb/s data rate as to achieve the space optical communication at high data rate. Speaking of the data rate of 40Gb/s, we must apply waveguide modulator to modulate the optical signal and magnify this signal by laser amplifier. Moreover, the more sensitive avalanche photodiode (APD) will be as the detector to increase the communication quality. Based on communication system above, we analyze character of communication quality in downlink of space optical communication system when data rate is at the level of 40Gb/s. The bit error rate (BER) performance, an important factor to justify communication quality, versus some parameter ratios is discussed. From results, there exists optimum ratio of gain factor and divergence angle, which shows the best BER performance. We can also increase ratio of receiving diameter and divergence angle for better communication quality. These results can be helpful to comprehend the character of optical communication system at high data rate and contribute to the system design.

  17. Approach to improve beam quality of inter-satellite optical communication system based on diffractive optical elements.

    PubMed

    Tan, Liying; Yu, Jianjie; Ma, Jing; Yang, Yuqiang; Li, Mi; Jiang, Yijun; Liu, Jianfeng; Han, Qiqi

    2009-04-13

    For inter-satellite optical communication transmitter with reflective telescope of two-mirrors on axis, a large mount of the transmitted energy will be blocked by central obscuration of the secondary mirror. In this paper, a novel scheme based on diffractive optical element (DOE) is introduced to avoid it. This scheme includes one diffractive beam shaper and another diffractive phase corrector, which can diffract the obscured part of transmitted beam into the domain unobscured by the secondary mirror. The proposed approach is firstly researched with a fixed obscuration ratio of 1/4. Numerical simulation shows that the emission efficiency of new figuration is 99.99%; the beam divergence from the novel inter-satellite optical communication transmitter is unchanged; and the peak intensity of receiver plane is increased about 31% compared with the typical configuration. Then the intensy patterns of receiver plane are analyzed with various obscuration ratio, the corresponding numerical modelling reveals that the intensity patterns with various obscuration ratio are nearly identical, but the amplify of relative peak intensity is getting down with the growth of obscuration ratio. This work can improve the beam quality of inter-satellite optical communication system without affecting any other functionality. PMID:19365457

  18. ICA-based compensation for IQ imbalance in OFDM optical fiber communication

    NASA Astrophysics Data System (ADS)

    Jiang, Shan; Hu, Guijun; Li, Zhaoxi; Mu, Liping; Zhang, Jingdong

    2014-01-01

    A method based on the independent component analysis (ICA) is proposed to compensate the in-phase and quadrature-phase the (IQ) imbalance in orthogonal frequency division multiplexing (OFDM) optical fiber communication systems. The mathematical model of IQ imbalance system has been analyzed. Then, ICA algorithm is applied in the system to combat the mirror interference introduced by IQ imbalance. This algorithm can realize the joint compensation of both transmitter and receiver IQ imbalance with the optical channel that contains noise, attenuation and chromatic dispersion. The simulation shows that the performance degradation caused by IQ imbalance can be compensated by ICA algorithm effectively.

  19. Fiber optic communication links

    SciTech Connect

    Meyer, R. H.

    1980-01-01

    Fiber optics is a new, emerging technology which offers relief from many of the problems which limited past communications links. Its inherent noise immunity and high bandwidth open the door for new designs with greater capabilities. Being a new technology, certain problems can be encountered in specifying and installing a fiber optic link. A general fiber optic system is discussed with emphasis on the advantages and disadvantages. It is not intended to be technical in nature, but a general discussion. Finally, a general purpose prototype Sandia communications link is presented.

  20. A new generation of IC based beam steering devices for free-space optical communication

    NASA Astrophysics Data System (ADS)

    Bedi, Vijit

    Free Space Optical (FSO) communication has tremendously advanced within the last decade to meet the ever increasing demand for higher communication bandwidth. Advancement in laser technology since its invention in the 1960's [1] attracted them to be the dominant source in FSO communication modules. The future of FSO systems lay in implementing semiconductor lasers due to their small size, power efficiency and mass fabrication abilities. In the near future, these systems are very likely to be used in space and ground based applications and revolutionary beam steering technologies will be required for distant communications in free-space. The highly directional characteristic inherent to a laser beam challenges and calls for new beam pointing and steering technologies for such type of communication. In this dissertation, research is done on a novel FSO communication device based on semiconductor lasers for high bandwidth communication. The "Fly eye transceiver" is an extremely wide steering bandwidth, completely non-mechanical FSO laser communication device primarily designed to replace traditional mechanical beam steering optical systems. This non-mechanical FSO device possesses a full spherical steering range and a very high tracking bandwidth. Inspired by the evolutionary model of a fly's eye, the full spherical steering range is assured by electronically controlled switching of its sub-eyes. Non mechanical technologies used in the past for beam steering such as acousto-optic Bragg cells, liquid crystal arrays or piezoelectric elements offer the wide steering bandwidth and fast response time, but are limited in their angular steering range. Mechanical gimbals offer a much greater steering range but face a much slower response time or steering bandwidth problem and often require intelligent adaptive controls with bulky driver amplifiers to feed their actuators. As a solution to feed both the fast and full spherical steering, the Fly-eye transceiver is studied as

  1. Channel estimation for OFDM system in atmospheric optical communication based on compressive sensing

    NASA Astrophysics Data System (ADS)

    Zhao, Qingsong; Hao, Shiqi; Geng, Hongjian; Sun, Han

    2015-10-01

    Orthogonal frequency division multiplexing (OFDM) technique applied to the atmospheric optical communication can improve data transmission rate, restrain pulse interference, and reduce effect of multipath caused by atmospheric scattering. Channel estimation, as one of the important modules in OFDM, has been investigated thoroughly and widely with great progress. In atmospheric optical communication system, channel estimation methods based on pilot are common approaches, such as traditional least-squares (LS) algorithm and minimum mean square error (MMSE) algorithm. However, sensitivity of the noise effects and high complexity of computation are shortcomings of LS algorithm and MMSE algorithm, respectively. Here, a new method based on compressive sensing is proposed to estimate the channel state information of atmospheric optical communication OFDM system, especially when the condition is closely associated with turbulence. Firstly, time-varying channel model is established under the condition of turbulence. Then, in consideration of multipath effect, sparse channel model is available for compressive sensing. And, the pilot signal is reconstructed with orthogonal matching tracking (OMP) algorithm, which is used for reconstruction. By contrast, the work of channel estimation is completed by LS algorithm as well. After that, simulations are conducted respectively in two different indexes -signal error rate (SER) and mean square error (MSE). Finally, result shows that compared with LS algorithm, the application of compressive sensing can improve the performance of SER and MSE. Theoretical analysis and simulation results show that the proposed method is reasonable and efficient.

  2. Hard plastic cladding fiber (HPCF) based optical components for high speed short reach optical communications

    NASA Astrophysics Data System (ADS)

    Kim, Jun Ki; Kim, Dong Uk; Kim, Tae Young; Park, Chang Soo; Oh, Kyunghwan

    2006-09-01

    We developed the primary components applicable to HPCF links for short reach (SR) and very short reach (VSR) data communication systems. We fabricated 4x4 HPCF fused taper splitter, HPCF pigtailed VCSEL and PIN photodiode for high speed short reach communications and characterized back to back transmission performance of the link composed of these components by measuring eye diagrams and jitters. Adapting the fusion-tapering technique for glass optical fiber, we successfully fabricated a 4x4 HPCF fused taper coupler. The HPCF with a core diameter of 200μm and an outer diameter of 230μm had step refractive index of 1.45 and 1.40 for the core and the clad. The optimized fusion length and tapering waist which make minimum insertion loss of about 7dB and uniform output power splitting ratio with less than 0.5dB are 13mm and 150µm, respectively. As a light source for VSR networks, we chose a vertical cavity surface emitting laser (VCSEL) and developed a package with a HPCF pigtail. After positioning VCSEL and HPCF that made a minimum coupling loss, we glued the HPCF inside ceramic ferrule housing. In HPCF-PIN PD packaging, we added a micro polymer lens tip onto the HPCF ends to match the mode field area to the sensitive area of GaAs or InGaAs PIN PD. Coupling between a PIN PD chip and the lensed HPCF was optimized with the radius of curvature of 156µm with a low coupling loss of 0.3dB, which is compatible to conventional MMF-PD packaging. For 1.25 Gbps data rate, the eyes adequate to eye mask in gigabit Ethernet were wide open after all HPCF transmission link and no significant power penalty was observed.

  3. Roadmap of optical communications

    NASA Astrophysics Data System (ADS)

    Agrell, Erik; Karlsson, Magnus; Chraplyvy, A. R.; Richardson, David J.; Krummrich, Peter M.; Winzer, Peter; Roberts, Kim; Fischer, Johannes Karl; Savory, Seb J.; Eggleton, Benjamin J.; Secondini, Marco; Kschischang, Frank R.; Lord, Andrew; Prat, Josep; Tomkos, Ioannis; Bowers, John E.; Srinivasan, Sudha; Brandt-Pearce, Maïté; Gisin, Nicolas

    2016-06-01

    Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.

  4. An extended-source spatial acquisition process based on maximum likelihood criterion for planetary optical communications

    NASA Technical Reports Server (NTRS)

    Yan, Tsun-Yee

    1992-01-01

    This paper describes an extended-source spatial acquisition process based on the maximum likelihood criterion for interplanetary optical communications. The objective is to use the sun-lit Earth image as a receiver beacon and point the transmitter laser to the Earth-based receiver to establish a communication path. The process assumes the existence of a reference image. The uncertainties between the reference image and the received image are modeled as additive white Gaussian disturbances. It has been shown that the optimal spatial acquisition requires solving two nonlinear equations to estimate the coordinates of the transceiver from the received camera image in the transformed domain. The optimal solution can be obtained iteratively by solving two linear equations. Numerical results using a sample sun-lit Earth as a reference image demonstrate that sub-pixel resolutions can be achieved in a high disturbance environment. Spatial resolution is quantified by Cramer-Rao lower bounds.

  5. Future optical communication networks beyond 160 Gbit/s based on OTDM

    NASA Astrophysics Data System (ADS)

    Prati, Giancarlo; Bogoni, Antonella; Poti, Luca

    2005-01-01

    The virtually unlimited bandwidth of optical fibers has caused a great increase in data transmission speed over the past decade and, hence, stimulated high-demand multimedia services such as distance learning, video-conferencing and peer to peer applications. For this reason data traffic is exceeding telephony traffic, and this trend is driving the convergence of telecommunications and computer communications. In this scenario Internet Protocol (IP) is becoming the dominant protocol for any traffic, shifting the attention of the network designers from a circuit switching approach to a packet switching approach. A role of paramount importance in packet switching networks is played by the router that must implement the functionalities to set up and maintain the inter-nodal communications. The main functionalities a router must implement are routing, forwarding, switching, synchronization, contention resolution, and buffering. Nowadays, opto-electronic conversion is still required at each network node to process the incoming signal before routing that to the right output port. However, when the single channel bit rate increases beyond electronic speed limit, Optical Time Division Multiplexing (OTDM) becomes a forced choice, and all-optical processing must be performed to extract the information from the incoming packet. In this paper enabling techniques for ultra-fast all-optical network will be addressed. First a 160 Gbit/s complete transmission system will be considered. As enabling technique, an overview for all-optical logics will be discussed and experimental results will be presented using a particular reconfigurable NOLM based on Self-Phase-Modulation (SPM) or Cross-Phase-Modulation (XPM). Finally, a rough experiment on label extraction, all-optical switching and packet forwarding is shown.

  6. Optically-Switched Resonant Tunneling Diodes for Space-Based Optical Communication Applications

    NASA Technical Reports Server (NTRS)

    Moise, T. S.; Kao, Y. -C.; Jovanovic, D.; Sotirelis, P.

    1995-01-01

    We are developing a new type of digital photo-receiver that has the potential to perform high speed optical-to-electronic conversion with a factor of 10 reduction in component count and power dissipation. In this paper, we describe the room-temperature photo-induced switching of this InP-based device which consists of an InGaAs/AlAs resonant tunneling diode integrated with an InGaAs absorber layer. When illuminated at an irradiance of greater than 5 Wcm(exp -2) using 1.3 micromillimeter radiation, the resonant tunneling diode switches from a high-conductance to a low-conductance electrical state and exhibits a voltage swing of up to 800 mV.

  7. Optical ranging and communication method based on all-phase FFT

    NASA Astrophysics Data System (ADS)

    Li, Zening; Chen, Gang

    2014-10-01

    This paper describes an optical ranging and communication method based on all-phase fast fourier transform (FFT). This kind of system is mainly designed for vehicle safety application. Particularly, the phase shift of the reflecting orthogonal frequency division multiplexing (OFDM) symbol is measured to determine the signal time of flight. Then the distance is calculated according to the time of flight. Several key factors affecting the phase measurement accuracy are studied. The all-phase FFT, which can reduce the effects of frequency offset, phase noise and the inter-carrier interference (ICI), is applied to measure the OFDM symbol phase shift.

  8. Performance degradation of QAM based inter-satellite optical communication system under gamma irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Li, Xuan

    2016-01-01

    Main devices in quadrature amplitude modulation (QAM) based inter-satellite optical communication system were irradiated to a total dose of 20 krad with the dose rate of 5 rad/s using a Co60 radiation source. Gamma irradiation impacts on devices were analyzed and on the basis, system performance degradation was simulated. Variety of system BER along with onboard working time for different inter-satellite links was presented. In addition, some adaption methods were proposed to reduce gamma irradiation induced degradation.

  9. Research on field of view of optical receiving antenna based on indoor visible light communication system

    NASA Astrophysics Data System (ADS)

    Gao, Mingguang; Lan, Tian; Zhao, Tao; Zhang, Yilun; Cui, Zhenghua; Ni, Guoqiang

    2015-08-01

    Optical receiving antenna is usually positioned before the detector of an indoor visible light communication (VLC) system in order to collect more optical energy into the detector. Besides optical gain of the antenna, the field of view (FOV) plays also an important role to the performance of a VLC system. In this paper, the signal noise ratio (SNR) and inter-symbol interference (ISI) versus FOV of the antenna are simulated via Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) links within a room with a size of 5m × 5m × 3m. Results show that, the blind area appears while the FOV is less than 40 deg. and the SNR reduces as FOV increases and keeps small when FOV is more than 70 deg.. Furthermore, the average power of ISI rises with the increase of FOV, and the rising trend is relatively moderate when FOV is below 50 deg., while there is a rapid increase between 50 deg. and 70 deg. and finally tends to be stable after 70 deg. Therefore, it is practical to determine the FOV of the optical receiving antenna in the scope of 40 to 50 deg. based on the installment of LED lights on the ceiling here so as to avoid the blind area, attain high SNR, and reduce the influence of ISI. It is also worthwhile in practice to provide an identifiable evidence for the determination of FOV of the optical antenna.

  10. Experimental demonstration of security-enhanced WDM-PON based on chaotic optical communications

    NASA Astrophysics Data System (ADS)

    Yin, Hongxi; Chen, Xiaolei; Yue, Hehe; Zhao, Qingchun; Hao, Yang; Wu, Chenguang; Zhao, Nan

    2015-08-01

    The message-decryption process of subtracting chaotic synchronization carrier from receiving signal is explained by modeling and numerically solving the rate equations for semiconductor lasers. An experimental system of wavelength division multiplexing passive optical network (WDM-PON) based on chaotic-light secure communications is first built up. The bidirectional transmissions of downstream and upstream data are experimentally realized with only two lasers and a single wavelength channel in a WDM fiber-optic link. When the data rate is 1.25 Gb/s, the secure transmission distance can be up to 11 km with SSMF of G.652. After sampling and decision, the BER of the recovered messages is calculated to be approximately 1×10-4.

  11. Optical Communications Channel Combiner

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Quirk, Kevin J.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    NASA has identified deep-space optical communications links as an integral part of a unified space communication network in order to provide data rates in excess of 100 Mb/s. The distances and limited power inherent in a deep-space optical downlink necessitate the use of photon-counting detectors and a power-efficient modulation such as pulse position modulation (PPM). For the output of each photodetector, whether from a separate telescope or a portion of the detection area, a communication receiver estimates a log-likelihood ratio for each PPM slot. To realize the full effective aperture of these receivers, their outputs must be combined prior to information decoding. A channel combiner was developed to synchronize the log-likelihood ratio (LLR) sequences of multiple receivers, and then combines these into a single LLR sequence for information decoding. The channel combiner synchronizes the LLR sequences of up to three receivers and then combines these into a single LLR sequence for output. The channel combiner has three channel inputs, each of which takes as input a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The cross-correlation between the channels LLR time series are calculated and used to synchronize the sequences prior to combining. The output of the channel combiner is a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The unit is controlled through a 1 Gb/s Ethernet UDP/IP interface. A deep-space optical communication link has not yet been demonstrated. This ground-station channel combiner was developed to demonstrate this capability and is unique in its ability to process such a signal.

  12. 1550 nm modulating retroreflector based on coated nanoparticles for free-space optical communication.

    PubMed

    Rosenkrantz, Etai; Arnon, Shlomi

    2015-06-10

    Nowadays, there is a renaissance in the field of space exploration. Current and future missions depend on astronauts and a swarm of robots for reconnaissance. In order to reduce the power consumption, weight, and size of the robots, an asymmetric communication system may be used. This is achieved by installing modulating retroreflectors (MRRs) on one side of the link and an interrogating laser on the other side. In this paper, we theoretically study an innovative device that can serve as an MRR in the infrared range of the spectrum. The device is based on a ferroelectric PZT thin film containing TiO2 coated Ag nanoparticles, which exhibit strong plasmonic resonance in the infrared range. After intensive analyses, which included calculations and simulations, we were able to design the device to operate at the 1550 nm wavelength. This is of great importance since the design of devices operating at 1550 nm as this wavelength is a mature technology widely used in free-space optics. Hence, this MRR can serve in asymmetric communication links relying on 1550 nm transmissions, which are also eye-safe. To the best of our knowledge, this is the first time coated metal nanoparticles have been proposed to modulate light in the infrared region. The performance of this device is unique, reaching a 17.5 dB modulation contrast with only a ±2 V operating voltage. This modulator may also be used for terrestrial communication such as fiber optics and optical interconnects in future data centers. PMID:26192828

  13. Underwater optical wireless communication network

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2010-01-01

    The growing need for underwater observation and subsea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, biogeochemical, evolutionary, and ecological changes in the sea, ocean, and lake environments, and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. Models are presented for three kinds of optical wireless communication links: (a) a line-of-sight link, (b) a modulating retroreflector link, and (c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered light it was possible to mitigate this decrease in some cases. It is concluded from the analysis that a high-data-rate underwater optical wireless network is a feasible solution for emerging applications such as UUV-to-UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  14. Optical Communications from Planetary Distances

    NASA Technical Reports Server (NTRS)

    Davarian, F.; Farr, W.; Hemmati, H.; Piazzolla, S.

    2008-01-01

    Future planetary campaigns, including human missions, will require data rates difficult to realize by microwave links. Optical channels not only provide an abundance of bandwidth, they also allow for significant size, weight, and power reduction. Moreover, optical-based tracking may enhance spacecraft navigation with respect to microwave-based tracking. With all its advantages, optical communications from deep space is not without its challenges. Due to the extreme distance between the two ends of the link, specialized technologies are needed to enable communications in the deep space environment. Although some of the relevant technologies have been developed in the last decade, they remain to be validated in an appropriate domain. The required assets include efficient pulsed laser sources, modulators, transmitters, receivers, detectors, channel encoders, precise beam pointing technologies for the flight transceiver and large apertures for the ground receiver. Clearly, space qualification is required for the systems that are installed on a deep space probe. Another challenge is atmospheric effects on the optical beam. Typical candidate locations on the ground have a cloud-free line of sight only on the order of 60-70% of the time. Furthermore, atmospheric losses and background light can be problematic even during cloud-free periods. Lastly, operational methodologies are needed for efficient and cost effective management of optical links. For more than a decade, the National Aeronautics and Space Administration (NASA) has invested in relevant technologies and procedures to enable deep space optical communications capable of providing robust links with rates in the order of 1 Gb/s from Mars distance. A recent publication indicates that potential exists for 30-dB improvement in performance through technology development with respect to the state-of-the-art in the early years of this decade. The goal is to fulfill the deep space community needs from about 2020 to the

  15. Detection of pointing errors with CMOS-based camera in intersatellite optical communications

    NASA Astrophysics Data System (ADS)

    Yu, Si-yuan; Ma, Jing; Tan, Li-ying

    2005-01-01

    For very high data rates, intersatellite optical communications hold a potential performance edge over microwave communications. Acquisition and Tracking problem is critical because of the narrow transmit beam. A single array detector in some systems performs both spatial acquisition and tracking functions to detect pointing errors, so both wide field of view and high update rate is required. The past systems tend to employ CCD-based camera with complex readout arrangements, but the additional complexity reduces the applicability of the array based tracking concept. With the development of CMOS array, CMOS-based cameras can employ the single array detector concept. The area of interest feature of the CMOS-based camera allows a PAT system to specify portion of the array. The maximum allowed frame rate increases as the size of the area of interest decreases under certain conditions. A commercially available CMOS camera with 105 fps @ 640×480 is employed in our PAT simulation system, in which only part pixels are used in fact. Beams angle varying in the field of view can be detected after getting across a Cassegrain telescope and an optical focus system. Spot pixel values (8 bits per pixel) reading out from CMOS are transmitted to a DSP subsystem via IEEE 1394 bus, and pointing errors can be computed by the centroid equation. It was shown in test that: (1) 500 fps @ 100×100 is available in acquisition when the field of view is 1mrad; (2)3k fps @ 10×10 is available in tracking when the field of view is 0.1mrad.

  16. Guest Editorial Atmospheric Optical Communication

    NASA Astrophysics Data System (ADS)

    Warde, Cardinal

    1981-02-01

    Fiber optic communication generally comes to mind first when one thinks or speaks of optical communication. In fact, the two terms are often used synonymously. Indeed, the fiber optic communication technology is maturing rapidly and it offers enor-mous advantages over unguided atmospheric optical propagation systems. However, there is a variety of applications for which fiber systems are impractical and for which atmospheric optical systems may be preferred. For example, short-haul, over-the-horizon links in areas where cable real estate rights are unobtain-able, or where an optical broadcast mode is desired, or for space-to-earth optical links.

  17. Optical communication components

    NASA Astrophysics Data System (ADS)

    Eldada, Louay

    2004-03-01

    We review and contrast key technologies developed to address the optical components market for communication applications. We first review the component requirements from a network perspective. We then look at different material systems, compare their properties, and describe the functions achieved to date in each of them. The material systems reviewed include silica fiber, silica on silicon, silicon on insulator, silicon oxynitride, sol-gels, polymers, thin-film dielectrics, lithium niobate, indium phosphide, gallium arsenide, magneto-optic materials, and birefringent crystals. We then describe the most commonly used classes of optical device technology and present their pros and cons as well as the functions achieved to date in each of them. The technologies reviewed include passive, actuation, and active technologies. The passive technologies described include fused fibers, dispersion-compensating fiber, beam steering, Bragg gratings, diffraction gratings, holographic elements, thin-film filters, photonic crystals, microrings, and birefringent elements. The actuation technologies include thermo-optics, electro-optics, acousto-optics, magneto-optics, electroabsorption, liquid crystals, total internal reflection technologies, and mechanical actuation. The active technologies include heterostructures, quantum wells, rare-earth doping, dye doping, Raman amplification, and semiconductor amplification. We also investigate the use of different material systems and device technologies to achieve building-block functions, including lasers, amplifiers, detectors, modulators, polarization controllers, couplers, filters, switches, attenuators, isolators, circulators, wavelength converters, chromatic dispersion compensators, and polarization mode dispersion compensators. Some of the technologies presented are well established in the industry and in some cases have reached the commodity stage, others have recently become ready for commercial introduction, while some others

  18. Background sources in optical communications

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.

    1983-01-01

    The characterization and measurement of background radiation relevant to optical communications system performance is addressed. The necessary optical receiver parameters are described, and radiometric concepts required for the calculation of collected background power are developed. The most important components of optical background power are discussed, and their contribution to the total collected background power in various communications scenarios is examined.

  19. High-rate-long-distance fiber-optic communication based on advanced modulation techniques.

    PubMed

    Ivankovski, Y; Mendlovic, D

    1999-09-10

    The presence of fiber attenuation and chromatic dispersion is one of the major design aspects of fiber-optic communication systems when one addresses high-rate and long-distance digital data transmission. Conventional digital communication systems implement a modulation technique that generates light pulses at the fiber input end and tries to detect them at the fiber output end. Here an advanced modulation transmission system is developed based on knowledge of the exact dispersion parameters of the fiber and the principles of space-time mathematical analogy. The information encodes the phase of the input light beam (a continuous laser beam). This phase is designed such that, when the signal is transmitted through a fiber with a given chromatic dispersion, high peak pulses emerge at the output, which follows a desired bit pattern. Thus the continuous input energy is concentrated into short time intervals in which the information needs to be represented at the output. The proposed method provides a high rate-distance product even for fibers with high dispersion parameters, high power at the output, and also unique protection properties. Theoretical analysis of the proposed method, computer simulations, and some design aspects are given. PMID:18324062

  20. Airborne Visible Laser Optical Communications Program (AVLOC)

    NASA Technical Reports Server (NTRS)

    Ward, J. H.

    1975-01-01

    The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

  1. Prediction of ionizing radiation effects induced performance degradation in homodyne BPSK based inter-satellite optical communication systems

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Li, Xuan; Dong, Chen

    2016-03-01

    Ionizing radiation effects induced on-orbit performance degradation in homodyne binary phase shift keying (BPSK) based inter-satellite optical communication system is predicted in this paper. Essential optoelectronic devices involved in optical communication system were irradiated by Co60 gamma ray and ionizing radiation environment of three general orbits was analyzed. On this basis, variations of terminal performance loss and system BER degradation along with on-orbit working time were simulated. Influences of terminal location and orbit environment were further discussed. Radiation protection on laser transmitters requires more strengthening, especially for those located in MEO and GEO satellites.

  2. Low Size, Weight and Power Concept for Mid-Wave Infrared Optical Communication Transceivers Based on Quantum Cascade Lasers

    NASA Technical Reports Server (NTRS)

    Luzhanskiy, Edward; Choa, Fow-Sen; Merritt, Scott; Yu, Anthony; Krainak, Michael

    2015-01-01

    The low complexity, low size, weight and power Mid-Wavelength Infra-Red optical communications transceiver concept presented, realized and tested in the laboratory environment. Resilience to atmospheric impairments analyzed with simulated turbulence. Performance compared to typical telecom based Short Wavelength Infra-Red transceiver.

  3. Compressed sensing theory-based channel estimation for optical orthogonal frequency division multiplexing communication system

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Li, Minghui; Wang, Ruyan; Liu, Yuanni; Song, Daiping

    2014-09-01

    Due to the spare multipath property of the channel, a channel estimation method, which is based on partial superimposed training sequence and compressed sensing theory, is proposed for line of sight optical orthogonal frequency division multiplexing communication systems. First, a continuous training sequence is added at variable power ratio to the cyclic prefix of orthogonal frequency division multiplexing symbols at the transmitter prior to transmission. Then the observation matrix of compressed sensing theory is structured by the use of the training symbols at receiver. Finally, channel state information is estimated using sparse signal reconstruction algorithm. Compared to traditional training sequences, the proposed partial superimposed training sequence not only improves the spectral efficiency, but also reduces the influence to information symbols. In addition, compared with classical least squares and linear minimum mean square error methods, the proposed compressed sensing theory based channel estimation method can improve both the estimation accuracy and the system performance. Simulation results are given to demonstrate the performance of the proposed method.

  4. OFDM-based broadband underwater wireless optical communication system using a compact blue LED

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Kong, Meiwei; Lin, Aobo; Song, Yuhang; Yu, Xiangyu; Qu, Fengzhong; Han, Jun; Deng, Ning

    2016-06-01

    We propose and experimentally demonstrate an IM/DD-OFDM-based underwater wireless optical communication system. We investigate the dependence of its BER performance on the training symbol number as well as LED's bias voltage and driving voltage. With single compact blue LED and a low-cost PIN photodiode, we achieve net bit rates of 225.90 Mb/s at a BER of 1.54×10-3 using 16-QAM and 231.95 Mb/s at a BER of 3.28×10-3 using 32-QAM, respectively, over a 2-m air channel. Over a 2-m underwater channel, we achieve net bit rates of 161.36 Mb/s using 16-QAM, 156.31 Mb/s using 32-QAM, and 127.07 Mb/s using 64-QAM, respectively. The corresponding BERs are 2.5×10-3, 7.42×10-4, and 3.17×10-3, respectively, which are all below the FEC threshold.

  5. Cost and Performance Comparison of an Earth-Orbiting Optical Communication Relay Transceiver and a Ground-Based Optical Receiver Subnet

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Wright, M.; Cesarone, R.; Ceniceros, J.; Shea, K.

    2003-01-01

    Optical communications can provide high-data-rate telemetry from deep-space probes with subsystems that have lower mass, consume less power, and are smaller than their radio frequency (RF) counterparts. However, because optical communication is more a.ected by weather than is RF communication, it requires groundstation site diversity to mitigate the adverse e.ects of inclement weather on the link. An optical relay satellite is not a.ected by weather and can provide 24-hour coverage of deep-space probes. Using such a relay satellite for the deep-space link and an 8.4-GHz (X-band) link to a ground station would support high-data-rate links from small deep-space probes with very little link loss due to inclement weather. We have reviewed past JPL-funded work on RF and optical relay satellites, and on proposed clustered and linearly dispersed optical subnets. Cost comparisons show that the life cycle costs of a 7-m optical relay station based on the heritage of the Next Generation Space Telescope is comparable to that of an 8-station subnet of 10- m optical ground stations. This makes the relay link an attractive option vis- a-vis a ground-station network.

  6. Optical Design of an Optical Communications Terminal

    NASA Technical Reports Server (NTRS)

    Biswas, Abhijit; Page, Norman; Hemmati, Hamid

    2005-01-01

    An optical communications terminal (OCT) is being developed to enable transmission of data at a rate as high as 2.5 Gb/s, from an aircraft or spacecraft to a ground station. In addition to transmitting high data rates, OCT will also be capable of bidirectional communications.

  7. Optical smart card using semipassive communication

    NASA Astrophysics Data System (ADS)

    Glaser, I.; Green, Shlomo; Dimkov, Ilan

    2006-03-01

    An optical secure short-range communication system is presented. The mobile unit (optical smart card) of this system utilizes a retroreflector with an optical modulator, using light from the stationary unit; this mobile unit has very low power consumption and can be as small as a credit card. Such optical smart cards offer better security than RF-based solutions, yet do not require physical contact. Results from a feasibility study model are included.

  8. Optical communication for space missions

    NASA Technical Reports Server (NTRS)

    Firtmaurice, M.

    1991-01-01

    Activities performed at NASA/GSFC (Goddard Space Flight Center) related to direct detection optical communications for space applications are discussed. The following subject areas are covered: (1) requirements for optical communication systems (data rates and channel quality; spatial acquisition; fine tracking and pointing; and transmit point-ahead correction); (2) component testing and development (laser diodes performance characterization and life testing; and laser diode power combining); (3) system development and simulations (The GSFC pointing, acquisition and tracking system; hardware description; preliminary performance analysis; and high data rate transmitter/receiver systems); and (4) proposed flight demonstration of optical communications.

  9. Towed Subsurface Optical Communications Buoy

    NASA Technical Reports Server (NTRS)

    Stirbl, Robert C.; Farr, William H.

    2013-01-01

    The innovation allows critical, high-bandwidth submarine communications at speed and depth. This reported innovation is a subsurface optical communications buoy, with active neutral buoyancy and streamlined flow surface veins for depth control. This novel subsurface positioning for the towed communications buoy enables substantial reduction in water-absorption and increased optical transmission by eliminating the intervening water absorption and dispersion, as well as by reducing or eliminating the beam spread and the pulse spreading that is associated with submarine-launched optical beams.

  10. Glossary of optical communication terms

    NASA Astrophysics Data System (ADS)

    Beaty, James S.

    1991-04-01

    This glossary contains definitions of technical terms commonly used in the field of optical communication. It is intended for those who already have a technical background (engineers, scientists, and technicians), but are not familiar with the terminology of optical communication. Readers should note that for purposes of Federal procurement, official definitions of terms related to telecommunication, of which optical communication is a subset, may be found in Federal Standard 1037A, Glossary of Telecommunications. (A revision, FS-1037B, is in preparation.) The present document contains a number of entries not found in FS-1037B, and although not legally an arbiter of the official definitions found there, serves in many cases to amplify and/or clarify those definitions, Also, among the notes accompanying the definitions herein are a number of mini-totorials that address certain matters which experience has shown to have led to confusion on the part of some individuals involved in one or more aspects of optical communication.

  11. Laser-based satellite communication systems stabilized by non-mechanical electro-optic scanners

    NASA Astrophysics Data System (ADS)

    Ziemkiewicz, Michael; Davis, Scott R.; Rommel, Scott D.; Gann, Derek; Luey, Benjamin; Gamble, Joseph D.; Anderson, Mike

    2016-05-01

    Laser communications systems provide numerous advantages for establishing satellite-to-ground data links. As a carrier for information, lasers are characterized by high bandwidth and directionality, allowing for fast and secure transfer of data. These systems are also highly resistant to RF influences since they operate in the infrared portion of the electromagnetic spectrum, far from radio bands. In this paper we will discuss an entirely non-mechanical electro-optic (EO) laser beam steering technology, with no moving parts, which we have used to form robust 400 Mbps optical data connections through air. This technology will enable low cost, compact, and rugged free space optical (FSO) communication modules for small satellite applications. The EO beam-steerer at the heart of this system is used to maintain beam pointing as the satellite orbits. It is characterized by extremely low values for size, weight and power consumption (SWaP) - approximately 300 cm3, 300 g, and 5 W respectively, which represents a marked improvement compared to heavy, and power-consuming gimbal mechanisms. It is capable of steering a 500 mW, 1 mm short wave infrared (SWIR) beam over a field of view (FOV) of up to 50° x 15°, a range which can be increased by adding polarization gratings, which provide a coarse adjust stage at the EO beam scanner output. We have integrated this device into a communication system and demonstrated the capability to lock on and transmit a high quality data stream by modulation of SWIR power.

  12. Experimental performance evaluation of software defined networking (SDN) based data communication networks for large scale flexi-grid optical networks.

    PubMed

    Zhao, Yongli; He, Ruiying; Chen, Haoran; Zhang, Jie; Ji, Yuefeng; Zheng, Haomian; Lin, Yi; Wang, Xinbo

    2014-04-21

    Software defined networking (SDN) has become the focus in the current information and communication technology area because of its flexibility and programmability. It has been introduced into various network scenarios, such as datacenter networks, carrier networks, and wireless networks. Optical transport network is also regarded as an important application scenario for SDN, which is adopted as the enabling technology of data communication networks (DCN) instead of general multi-protocol label switching (GMPLS). However, the practical performance of SDN based DCN for large scale optical networks, which is very important for the technology selection in the future optical network deployment, has not been evaluated up to now. In this paper we have built a large scale flexi-grid optical network testbed with 1000 virtual optical transport nodes to evaluate the performance of SDN based DCN, including network scalability, DCN bandwidth limitation, and restoration time. A series of network performance parameters including blocking probability, bandwidth utilization, average lightpath provisioning time, and failure restoration time have been demonstrated under various network environments, such as with different traffic loads and different DCN bandwidths. The demonstration in this work can be taken as a proof for the future network deployment. PMID:24787842

  13. Network coding based joint signaling and dynamic bandwidth allocation scheme for inter optical network unit communication in passive optical networks

    NASA Astrophysics Data System (ADS)

    Wei, Pei; Gu, Rentao; Ji, Yuefeng

    2014-06-01

    As an innovative and promising technology, network coding has been introduced to passive optical networks (PON) in recent years to support inter optical network unit (ONU) communication, yet the signaling process and dynamic bandwidth allocation (DBA) in PON with network coding (NC-PON) still need further study. Thus, we propose a joint signaling and DBA scheme for efficiently supporting differentiated services of inter ONU communication in NC-PON. In the proposed joint scheme, the signaling process lays the foundation to fulfill network coding in PON, and it can not only avoid the potential threat to downstream security in previous schemes but also be suitable for the proposed hybrid dynamic bandwidth allocation (HDBA) scheme. In HDBA, a DBA cycle is divided into two sub-cycles for applying different coding, scheduling and bandwidth allocation strategies to differentiated classes of services. Besides, as network traffic load varies, the entire upstream transmission window for all REPORT messages slides accordingly, leaving the transmission time of one or two sub-cycles to overlap with the bandwidth allocation calculation time at the optical line terminal (the OLT), so that the upstream idle time can be efficiently eliminated. Performance evaluation results validate that compared with the existing two DBA algorithms deployed in NC-PON, HDBA demonstrates the best quality of service (QoS) support in terms of delay for all classes of services, especially guarantees the end-to-end delay bound of high class services. Specifically, HDBA can eliminate queuing delay and scheduling delay of high class services, reduce those of lower class services by at least 20%, and reduce the average end-to-end delay of all services over 50%. Moreover, HDBA also achieves the maximum delay fairness between coded and uncoded lower class services, and medium delay fairness for high class services.

  14. Experimental optical fiber communications link

    NASA Technical Reports Server (NTRS)

    Lutes, G. F.

    1980-01-01

    An optical fiber communications link 1.5 kilometers in length was installed between the Interim Frequency Standard Test Facility and the Timing and Frequency Systems Research Laboratory at JPL. It is being used to develop optical fiber technology for use in the DSN and particularly for precise time and frequency distribution.

  15. MEMS for optical communication: present and future

    NASA Astrophysics Data System (ADS)

    Pu, Chuan; Lee, Shi-sheng; Park, Sangtae; Chu, Patrick B.; Brener, Igal

    2002-07-01

    The current fiber optical communication system has evolved into a complicated multi-wavelength system with the deployment of Wavelength Division Multiplexing (WDM) networks. Many innovative technologies are desired to materialize its vast capacities and promises. MEMS technology has recently emerged as a competitive candidate to solve many technical challenges encountered in current WDM networks. Its applications have spanned from large scale optical switch fabrics such as optical cross-connects, optical add/drop multiplexers, to a large variety of active and passive optical components for transmission networks, such as tunable lasers and filters, dispersion compensation devices, amplifier gain equalizers, polarization controllers, and many others. In this paper we will discuss the current development status, promises and challenges, and the future prospects of MEMS technologies for optical communication, with a primary focus on MEMS-based optical cross-connects.

  16. Optical Communications and Sensor Demonstration

    NASA Technical Reports Server (NTRS)

    Martinez, Andres; Petro, Andrew

    2015-01-01

    The Optical Communications and Sensor Demonstration (OCSD) project addresses two cross-cutting capabilities of value to many future small spacecraft missions: high-speed optical transmission of data and small spacecraft proximity operations. Optical data rates demonstrated by OCSD are expected to be 200 megabits persecond (Mbs) or higher, a factor of 100 increase over current high-end CubeSat communications systems. The proximity sensors developed for this mission enable relative position measurement between two small satellites - a capability not previously demonstrated.

  17. Optical communications for transport aircraft

    NASA Technical Reports Server (NTRS)

    Stengel, Robert

    1994-01-01

    Optical communications for transport aircraft are discussed. The problem involves: increasing demand for radio-frequency bands from an enlarging pool of users (aircraft, ground and sea vehicles, fleet operators, traffic control centers, and commercial radio and television); desirability of providing high-bandwidth dedicated communications to and from every aircraft in the National Airspace System; need to support communications, navigation, and surveillance for a growing number of aircraft; and improved meteorological observations by use of probe aircraft. The solution involves: optical signal transmission support very high data rates; optical transmission of signals between aircraft, orbiting satellites, and ground stations, where unobstructed line-of-sight is available; conventional radio transmissions of signals between aircraft and ground stations, where optical line-of-sight is unavailable; and radio priority given to aircraft in weather.

  18. Great circle solution to polarization-based quantum communication (QC) in optical fiber

    DOEpatents

    Nordholt, Jane Elizabeth; Peterson, Charles Glen; Newell, Raymond Thorson; Hughes, Richard John

    2016-03-15

    Birefringence in optical fibers is compensated by applying polarization modulation at a receiver. Polarization modulation is applied so that a transmitted optical signal has states of polarization (SOPs) that are equally spaced on the Poincare sphere. Fiber birefringence encountered in propagation between a transmitter and a receiver rotates the great circle on the Poincare sphere that represents the polarization bases used for modulation. By adjusting received polarizations, polarization components of the received optical signal can be directed to corresponding detectors for decoding, regardless of the magnitude and orientation of the fiber birefringence. A transmitter can be configured to transmit in conjugate polarization bases whose SOPs can be represented as equidistant points on a great circle so that the received SOPs are mapped to equidistant points on a great circle and routed to corresponding detectors.

  19. A blind detection scheme based on modified wavelet denoising algorithm for wireless optical communications

    NASA Astrophysics Data System (ADS)

    Li, Ruijie; Dang, Anhong

    2015-10-01

    This paper investigates a detection scheme without channel state information for wireless optical communication (WOC) systems in turbulence induced fading channel. The proposed scheme can effectively diminish the additive noise caused by background radiation and photodetector, as well as the intensity scintillation caused by turbulence. The additive noise can be mitigated significantly using the modified wavelet threshold denoising algorithm, and then, the intensity scintillation can be attenuated by exploiting the temporal correlation of the WOC channel. Moreover, to improve the performance beyond that of the maximum likelihood decision, the maximum a posteriori probability (MAP) criterion is considered. Compared with conventional blind detection algorithm, simulation results show that the proposed detection scheme can improve the signal-to-noise ratio (SNR) performance about 4.38 dB while the bit error rate and scintillation index (SI) are 1×10-6 and 0.02, respectively.

  20. All-optical signal processing technique for secure optical communication

    NASA Astrophysics Data System (ADS)

    Qian, Feng-chen; Su, Bing; Ye, Ya-lin; Zhang, Qian; Lin, Shao-feng; Duan, Tao; Duan, Jie

    2015-10-01

    Secure optical communication technologies are important means to solve the physical layer security for optical network. We present a scheme of secure optical communication system by all-optical signal processing technique. The scheme consists of three parts, as all-optical signal processing unit, optical key sequence generator, and synchronous control unit. In the paper, all-optical signal processing method is key technology using all-optical exclusive disjunction (XOR) gate based on optical cross-gain modulation effect, has advantages of wide dynamic range of input optical signal, simple structure and so on. All-optical XOR gate composed of two semiconductor optical amplifiers (SOA) is a symmetrical structure. By controlling injection current, input signal power, delay and filter bandwidth, the extinction ratio of XOR can be greater than 8dB. Finally, some performance parameters are calculated and the results are analyzed. The simulation and experimental results show that the proposed method can be achieved over 10Gbps optical signal encryption and decryption, which is simple, easy to implement, and error-free diffusion.

  1. Single mode optical fiber based devices and systems for mid-infrared light generation, communication and metrology

    NASA Astrophysics Data System (ADS)

    Kulkarni, Ojas P.

    Fiber-optic systems and devices for broadband mid-infrared light generation, communication and optical metrology are developed in this thesis. Using the nonlinear properties of low mid-infrared loss ZrF4-BaF 2-LaF3-AlF3-NaF (ZBLAN) fiber, a mid-infrared supercontinuum (SC) laser based on a thulium-doped fiber amplifier (TDFA) with spectrum extending from ˜1.9-4.5 microm is demonstrated. A higher efficiency, power-scalable, all-fiber integrated mid-infrared light source is realized capable of generating ˜0.7 W time-average power in wavelengths beyond 3.8 microm. The novelty of the laser lies in its two-step spectral shifting architecture. First, amplified laser diode pulses at 1.55 microm are used to generate a SC extending beyond 2 microm in standard SMF using modulation-instability initiated pulse break-up. A TDFA stage is then used to amplify the ˜2 microm components in the standard SMF continuum. By subsequently coupling the amplified ˜2 microm pulses in to a ZBLAN fiber, an SC with up to ˜2.6 W average power, and ˜9% optical conversion efficiency from the power-amp pump to mid-IR output is demonstrated. The two-step methodology leads to extension in the long wavelength edge of the SC from 4.2 microm to ˜4.5 microm, compared to previously demonstrated systems and ˜2.5 times higher optical efficiency in generating wavelengths beyond 3.8 microm. Numerical simulations are also presented based on solving the generalized non-linear Schrodinger equation to verify and extend experimental results. A broadband surface-normal optical modulator for communication applications with operation demonstrated over 1200--2400 nm is also presented. The modulator uses free-carrier effect in GaAs and mode selectivity of SMF to generate up to ˜43% modulation depth with a maximum operating speed of ˜270 MHz. The broad wavelength range of operation of the modulator can potentially enable higher throughput wavelength-division multiplexed optical network architectures based on

  2. Deep space optical communications experiment

    NASA Technical Reports Server (NTRS)

    Kinman, P.; Katz, J.; Gagliardi, R.

    1983-01-01

    An optical communications experiment between a deep space vehicle and an earth terminal is under consideration for later in this decade. The experimental link would be incoherent (direct detection) and would employ two-way cooperative pointing. The deep space optical transceiver would ride piggyback on a spacecraft with an independent scientific objective. Thus, this optical transceiver is being designed for minimum spacecraft impact - specifically, low mass and low power. The choices of laser transmitter, coding/modulation scheme, and pointing mechanization are discussed. A representative telemetry link budget is presented.

  3. Gamma radiation impact on performance of OOK, DPSK and homodyne BPSK based optical inter-satellite communication system

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Hou, Rui; Qiang, Ruoxin

    2015-09-01

    Performance of optical inter-satellite communication system is influenced by the harsh space radiation environment. Gamma radiation effects on main devices of communication system are analyzed and on the basis of existing experimental data, performance degradation of on off keying (OOK), differential phase shift keying (DPSK) and homodyne binary phase shift keying (BPSK) based system under 1 kGy gamma irradiation is simulated. Variation of Q factors and bit error ratio of these systems with different radiation position are achieved and discussed. The result shows that it is more urgent to improve the radiation hardness of transmitter, and the introduction of local laser is a considerable method to reduce gamma radiation impact on system performance.

  4. Optical orbital angular momentum for optical communication and its measurements

    NASA Astrophysics Data System (ADS)

    Ke, Xi-zheng; Lv, Hong; Wu, Jing-zhi; Hu, Shu-qiao

    2009-07-01

    The beam with orbital angular momentum is a present domestic and foreign research key direction. Its application and development will bring the profound influence in the optical communications field. At the same time, light's orbital angular momentum promises potential applications in both classical and quantum optical communication. The research progress of the beam with orbital angular momentum and encoding information as light's OAM for free-space optical communication were reviewed in this article, the existing design method, mechanism and description methods of encoding information as light's OAM were discussed. In quantum communication, qudits can be encoded in photons using their OAM for creating high-dimensional entanglement based on entangled photon pairs from SPDC. In this paper, light's OAM is used as information carrier for classical and quantum communication, which is promising to ensures the security of atmospheric laser communication, improves the density and precision of information transmission. It is apparent that an efficient way to measure the orbital angular momentum of individual photons and light beams with good efficiency would be of potentially great importance for optical communications and quantum information. In view of the above, the measurements of orbital angular momentum of individual photons and light beams are analyzed and discussed in detail.

  5. Subsea fiber-optic communications

    SciTech Connect

    High, G.; Wright, P.J.

    1997-05-01

    High-cost and hazardous nature of recovering hydrocarbons offshore have led to the trend towards growth in subsea production control. The extended step-out distances of subsea completions is increasing the volume and complexity of subsea data communications beyond the capacity of conventional systems. Improved reservoir management using intelligent sensors, metering, and process equipment, requiring real-time monitoring and control, dictates the use of wideband communication. Fiber optics offers the necessary volume of data transmission, with the high-noise immunity needed for data integrity and safe operation, under the severe Electro-Magnetic Interference (EMI) environments created where high power motors and power cables are used subsea. The marinizing of optical, opto-electronic communication components for production control, data acquisition of subsea completions for the offshore oil industry are described.

  6. Orbital Angular Momentum-based Space Division Multiplexing for High-capacity Underwater Optical Communications.

    PubMed

    Ren, Yongxiong; Li, Long; Wang, Zhe; Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Arbabi, Amir; Zhao, Zhe; Xie, Guodong; Cao, Yinwen; Ahmed, Nisar; Yan, Yan; Liu, Cong; Willner, Asher J; Ashrafi, Solyman; Tur, Moshe; Faraon, Andrei; Willner, Alan E

    2016-01-01

    To increase system capacity of underwater optical communications, we employ the spatial domain to simultaneously transmit multiple orthogonal spatial beams, each carrying an independent data channel. In this paper, we show up to a 40-Gbit/s link by multiplexing and transmitting four green orbital angular momentum (OAM) beams through a single aperture. Moreover, we investigate the degrading effects of scattering/turbidity, water current, and thermal gradient-induced turbulence, and we find that thermal gradients cause the most distortions and turbidity causes the most loss. We show systems results using two different data generation techniques, one at 1064 nm for 10-Gbit/s/beam and one at 520 nm for 1-Gbit/s/beam; we use both techniques since present data-modulation technologies are faster for infrared (IR) than for green. For the 40-Gbit/s link, data is modulated in the IR, and OAM imprinting is performed in the green using a specially-designed metasurface phase mask. For the 4-Gbit/s link, a green laser diode is directly modulated. Finally, we show that inter-channel crosstalk induced by thermal gradients can be mitigated using multi-channel equalisation processing. PMID:27615808

  7. Analysis of message extraction in optical chaos communications based on injection-locking synchronization of semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Murakami, Atsushi; Shore, K. Alan

    2006-10-01

    In this paper, we employ a simple theory based on driven damped oscillators to clarify the physical basis for message extraction in optical chaos communications using injection-locked semiconductor lasers. The receiver laser is optically driven by injection from the transmitter laser. We have numerically investigated the response characteristics of the receiver when it is driven by periodic (message) and chaotic (carrier) signals. It is thereby revealed that the response of the receiver laser in the two cases is quite different. For the periodic drive, the receiver exhibits a response depending on the signal frequency, while the chaotic drive provides a frequency-independent synchronous response to the receiver laser. CPF can be clearly understood in the difference between the periodic and chaotic drives. Message extraction using CPF is also examined, and the validity of our theoretical explanation for the physical mechanism underlying CPF is thus verified.

  8. Performance comparison of a fiber optic communication system based on optical OFDM and an optical OFDM-MIMO with Alamouti code by using numerical simulations

    NASA Astrophysics Data System (ADS)

    Serpa-Imbett, C. M.; Marín-Alfonso, J.; Gómez-Santamaría, C.; Betancur-Agudelo, L.; Amaya-Fernández, F.

    2013-12-01

    Space division multiplexing in multicore fibers is one of the most promise technologies in order to support transmissions of next-generation peta-to-exaflop-scale supercomputers and mega data centers, owing to advantages in terms of costs and space saving of the new optical fibers with multiple cores. Additionally, multicore fibers allow photonic signal processing in optical communication systems, taking advantage of the mode coupling phenomena. In this work, we numerically have simulated an optical MIMO-OFDM (multiple-input multiple-output orthogonal frequency division multiplexing) by using the coded Alamouti to be transmitted through a twin-core fiber with low coupling. Furthermore, an optical OFDM is transmitted through a core of a singlemode fiber, using pilot-aided channel estimation. We compare the transmission performance in the twin-core fiber and in the singlemode fiber taking into account numerical results of the bit-error rate, considering linear propagation, and Gaussian noise through an optical fiber link. We carry out an optical fiber transmission of OFDM frames using 8 PSK and 16 QAM, with bit rates values of 130 Gb/s and 170 Gb/s, respectively. We obtain a penalty around 4 dB for the 8 PSK transmissions, after 100 km of linear fiber optic propagation for both singlemode and twin core fiber. We obtain a penalty around 6 dB for the 16 QAM transmissions, with linear propagation after 100 km of optical fiber. The transmission in a two-core fiber by using Alamouti coded OFDM-MIMO exhibits a better performance, offering a good alternative in the mitigation of fiber impairments, allowing to expand Alamouti coded in multichannel systems spatially multiplexed in multicore fibers.

  9. Atmospheric propagation effects relevant to optical communications

    NASA Technical Reports Server (NTRS)

    Shaik, K. S.

    1988-01-01

    A number of atmospheric phenomena affect the propagation of light. The effects of clear air turbulence are reviewed as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study. Useful information on the atmospheric propagation of light in relation to optical deep space communications to an earth based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

  10. Design And Analysis Of Optical Communication Links

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.; Marshall, W. K.; Katz, J.

    1989-01-01

    To convey to prospective designers intuitive understanding based on unique characteristics of optical communication systems, report presents method of design and analysis of outer-space optical communication link using pulse-position modulation (PPM) and in which received signal sufficiently weak to require detection by photomultiplier operating in photon-counting mode. Step 1 requires some knowledge or assumptions about parameters of transmitter and receiver. Step 2 determination of average number of background-noise photons detected during PPM timeslot. Step 3 average number, Ps of signal photons detected per signal pulse compared with average number, Pn of noise pulses detected per PPM timeslot.

  11. Atmospheric Propagation Effects Relevant to Optical Communications

    NASA Technical Reports Server (NTRS)

    Shaik, K. S.

    1988-01-01

    A number of atmospheric phenomena affect the propagation of light. This article reviews the effects of clear-air turbulence as well as atmospheric turbidity on optical communications. Among the phenomena considered are astronomical and random refraction, scintillation, beam broadening, spatial coherence, angle of arrival, aperture averaging, absorption and scattering, and the effect of opaque clouds. An extensive reference list is also provided for further study, Useful information on the atmospheric propagation of light in resolution to optical deep-space communications to an earth-based receiving station is available, however, further data must be generated before such a link can be designed with committed performance.

  12. Technology Development for High Efficiency Optical Communications

    NASA Technical Reports Server (NTRS)

    Farr, William H.

    2012-01-01

    Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

  13. Optical Filter Assembly for Interplanetary Optical Communications

    NASA Technical Reports Server (NTRS)

    Chen, Yijiang; Hemmati, Hamid

    2013-01-01

    Ground-based, narrow-band, high throughput optical filters are required for optical links from deep space. We report on the development of a tunable filter assembly that operates at telecommunication window of 1550 nanometers. Low insertion loss of 0.5 decibels and bandwidth of 90 picometers over a 2000 nanometers operational range of detectors has been achieved.

  14. Heralded quantum repeater for a quantum communication network based on quantum dots embedded in optical microcavities

    NASA Astrophysics Data System (ADS)

    Li, Tao; Yang, Guo-Jian; Deng, Fu-Guo

    2016-01-01

    We propose a heralded quantum repeater protocol based on the general interface between the circularly polarized photon and the quantum dot embedded in a double-sided optical microcavity. Our effective time-bin encoding on photons results in the deterministic faithful entanglement distribution with one optical fiber for the transmission of each photon in our protocol, not two or more. Our efficient parity-check detector implemented with only one input-output process of a single photon as a result of cavity quantum electrodynamics makes the entanglement channel extension and entanglement purification in quantum repeater far more efficient than others, and it has the potential application in fault-tolerant quantum computation as well. Meanwhile, the deviation from a collective-noise channel leads to some phase-flip errors on the nonlocal electron spins shared by the parties and these errors can be depressed by our simplified entanglement purification process. Finally, we discuss the performance of our proposal, concluding that it is feasible with current technology.

  15. Polarization compensator for optical communications

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, M. W.; Abshire, J. B. (Inventor)

    1976-01-01

    An optical data communication system is provided whereby two orthogonal polarization states of a light beam carrier correspond to digital states. In such a system, automatic polarization compensation is provided by applying a dither modulating voltage to a cell exhibiting the electro-optic effect. The cell controls the relative phase of electric field components of an input light beam enabling the dither frequency component of the difference of the instantaneous powers in the two polarization states to be coherently detected. A signal derived from the coherent detection process is fed back to the cell via an integrator to form polarization bias compensating servo loop ot Type 1.

  16. Adaptive Optics Communications Performance Analysis

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.; Troy, M.; Wilson, K.

    2004-01-01

    The performance improvement obtained through the use of adaptive optics for deep-space communications in the presence of atmospheric turbulence is analyzed. Using simulated focal-plane signal-intensity distributions, uncoded pulse-position modulation (PPM) bit-error probabilities are calculated assuming the use of an adaptive focal-plane detector array as well as an adaptively sized single detector. It is demonstrated that current practical adaptive optics systems can yield performance gains over an uncompensated system ranging from approximately 1 dB to 6 dB depending upon the PPM order and background radiation level.

  17. A novel super-FEC code based on concatenated code for high-speed long-haul optical communication systems

    NASA Astrophysics Data System (ADS)

    Yuan, Jianguo; Ye, Wenwei; Jiang, Ze; Mao, Youju; Wang, Wei

    2007-05-01

    The structures of the novel super forward error correction (Super-FEC) code type based on the concatenated code for high-speed long-haul optical communication systems are studied in this paper. The Reed-Solomon (RS) (255, 239) + Bose-Chaudhuri-Hocguenghem (BCH) (1023, 963) concatenated code is presented after the characteristics of the concatenated code and the two Super-FEC code type presented in ITU-T G.975.1 have theoretically been analyzed, the simulation result shows that this novel code type, compared with the RS (255, 239) + convolutional-self-orthogonal-code (CSOC) ( k0/ n0 = 6/7, J = 8) code in ITU-T G.975.1, has a lower redundancy and better error-correction capabilities, and its net coding gain (NCG) at the third iteration is 0.57 dB more than that of RS (255, 239) + CSOC ( k0/ n0 = 6/7, J = 8) code in ITU-T G.975.1 at the third iteration for the bit error rate (BER) of 10 -12. Therefore, the novel code type can better be used in long-haul, larger capacity and higher bit-rate optical communication systems. Furthermore, the design and implementation of the novel concatenated code type are also discussed.

  18. An underwater optical wireless communication network

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2009-08-01

    The growing need for underwater observation and sub-sea monitoring systems has stimulated considerable interest in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. This communication technology is expected to play an important role in investigating climate change, in monitoring biological, bio-geochemical, evolutionary and ecological changes in the sea, ocean and lake environments and in helping to control and maintain oil production facilities and harbors using unmanned underwater vehicles (UUVs), submarines, ships, buoys, and divers. However, the present technology of underwater acoustic communication cannot provide the high data rate required to investigate and monitor these environments and facilities. Optical wireless communication has been proposed as the best alternative to meet this challenge. We present models of three kinds of optical wireless communication links a) a line-of-sight link, b) a modulating retro-reflector link and c) a reflective link, all of which can provide the required data rate. We analyze the link performance based on these models. From the analysis, it is clear that as the water absorption increases, the communication performance decreases dramatically for the three link types. However, by using the scattered lighted it was possible to mitigate this decrease in some cases. We conclude from the analysis that a high data rate underwater optical wireless network is a feasible solution for emerging applications such as UUV to UUV links and networks of sensors, and extended ranges in these applications could be achieved by applying a multi-hop concept.

  19. A novel construction method of QC-LDPC codes based on CRT for optical communications

    NASA Astrophysics Data System (ADS)

    Yuan, Jian-guo; Liang, Meng-qi; Wang, Yong; Lin, Jin-zhao; Pang, Yu

    2016-05-01

    A novel construction method of quasi-cyclic low-density parity-check (QC-LDPC) codes is proposed based on Chinese remainder theory (CRT). The method can not only increase the code length without reducing the girth, but also greatly enhance the code rate, so it is easy to construct a high-rate code. The simulation results show that at the bit error rate ( BER) of 10-7, the net coding gain ( NCG) of the regular QC-LDPC(4 851, 4 546) code is respectively 2.06 dB, 1.36 dB, 0.53 dB and 0.31 dB more than those of the classic RS(255, 239) code in ITU-T G.975, the LDPC(32 640, 30 592) code in ITU-T G.975.1, the QC-LDPC(3 664, 3 436) code constructed by the improved combining construction method based on CRT and the irregular QC-LDPC(3 843, 3 603) code constructed by the construction method based on the Galois field ( GF( q)) multiplicative group. Furthermore, all these five codes have the same code rate of 0.937. Therefore, the regular QC-LDPC(4 851, 4 546) code constructed by the proposed construction method has excellent error-correction performance, and can be more suitable for optical transmission systems.

  20. Avalanche Photodiode Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.

    2001-01-01

    An avalanche photodiode (APD) array for ground-based optical communications receivers is investigated for the reception of optical signals through the turbulent atmosphere. Kolmogorov phase screen simulations are used to generate realistic spatial distributions of the received optical field. It is shown that use of an APD array for pulse-position modulation detection can improve performance by up to 4 dB over single APD detection in the presence of turbulence, but that photon-counting detector arrays yield even greater gains.

  1. Received optical power calculations for optical communications link performance analysis

    NASA Technical Reports Server (NTRS)

    Marshall, W. K.; Burk, B. D.

    1986-01-01

    The factors affecting optical communication link performance differ substantially from those at microwave frequencies, due to the drastically differing technologies, modulation formats, and effects of quantum noise in optical communications. In addition detailed design control table calculations for optical systems are less well developed than corresponding microwave system techniques, reflecting the relatively less mature state of development of optical communications. Described below are detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses.

  2. Commercialization and Standardization Progress Towards an Optical Communications Earth Relay

    NASA Technical Reports Server (NTRS)

    Edwards, Bernard L.; Israel, David J.

    2015-01-01

    NASA is planning to launch the next generation of a space based Earth relay in 2025 to join the current Space Network, consisting of Tracking and Data Relay Satellites in space and the corresponding infrastructure on Earth. While the requirements and architecture for that relay satellite are unknown at this time, NASA is investing in communications technologies that could be deployed to provide new communications services. One of those new technologies is optical communications. The Laser Communications Relay Demonstration (LCRD) project, scheduled for launch in 2018 as a hosted payload on a commercial communications satellite, is a critical pathfinder towards NASA providing optical communications services on the next generation space based relay. This paper will describe NASA efforts in the on-going commercialization of optical communications and the development of inter-operability standards. Both are seen as critical to making optical communications a reality on future NASA science and exploration missions. Commercialization is important because NASA would like to eventually be able to simply purchase an entire optical communications terminal from a commercial provider. Inter-operability standards are needed to ensure that optical communications terminals developed by one vendor are compatible with the terminals of another. International standards in optical communications would also allow the space missions of one nation to use the infrastructure of another.

  3. Staying coherent after kent: From optical communications to biomedical optics

    NASA Astrophysics Data System (ADS)

    Sampson, David D.

    2011-12-01

    In this paper, an overview of author's research is presented, commencing at the University of Kent under Prof. David A. Jackson. Early research in short optical pulses and fiber-optic delay-line digital correlators led to optical communications research in code-division multiple access networking. This research was based on broadband incoherent light, and this theme continued with research into spectrum-sliced wavelength-division multiplexing. In shifting from photonics research to biomedical optics and biophotonics in the late 1990s, the emphasis on exploiting broadband light continued with research in optical coherence tomography, amongst other topics. In addition to the research outcomes, how these outcomes were attained is described, including mention of the exceptional contributions of many of my colleagues.

  4. Coherent communication with linear optics

    SciTech Connect

    Wilde, Mark M.; Brun, Todd A.; Dowling, Jonathan P.; Lee, Hwang

    2008-02-15

    We show how to implement several continuous-variable coherent protocols with linear optics. Noise can accumulate when implementing each coherent protocol with realistic optical devices. Our analysis bounds the level of noise accumulation. We highlight the connection between a coherent channel and a nonlocal quantum nondemolition interaction and give two new protocols that implement a coherent channel. One protocol is superior to a previous method for a nonlocal quantum nondemolition interaction because it requires fewer communication resources. We then show how continuous-variable coherent superdense coding implements two nonlocal quantum nondemolition interactions with a quantum channel and bipartite entanglement. We finally show how to implement continuous-variable coherent teleportation experimentally and provide a way to verify the correctness of its operation.

  5. Optimal optical communication terminal structure for maximizing the link budget

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Jiang, Dagang; Deng, Ke; Zhang, Peng

    2015-02-01

    Ordinary inter-satellite optical includes at least three optical paths for acquisition, tracking and communication, the three optical paths work simultaneously and share the received power. An optimal structure of inter-satellite optical communication terminal with single working optical path at each of working stages of acquisition and communication is introduced. A space optical switch based on frustrated total internal reflection effect is applied to switch the received laser power between the acquisition sensor and the communication sensor between the stages of acquisition and communication, this is named as power fusion which means power is transferred for shutting down unused optical path. For the stages of tracking and communication, a multiple cells sensor is used to accomplish the operation of tracking while communication, this is named as function fusion which means accomplishing multiple functions by one device to reduce the redundant optical paths. For optical communication terminal with single working path structure, the total received laser power would be detected by one sensor for each different stages of acquisition, tracking and communication, the link budget would be maximized, and this design would help to enlarge the system tolerance and reduce the acquisition time.

  6. Radio Science from an Optical Communications Signal

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Asmar, Sami; Oudrhiri, Kamal

    2013-01-01

    NASA is currently developing the capability to deploy deep space optical communications links. This creates the opportunity to utilize the optical link to obtain range, doppler, and signal intensity estimates. These may, in turn, be used to complement or extend the capabilities of current radio science. In this paper we illustrate the achievable precision in estimating range, doppler, and received signal intensity of an non-coherent optical link (the current state-of-the-art for a deep-space link). We provide a joint estimation algorithm with performance close to the bound. We draw comparisons to estimates based on a coherent radio frequency signal, illustrating that large gains in either precision or observation time are possible with an optical link.

  7. Affordable underwater wireless optical communication using LEDs

    NASA Astrophysics Data System (ADS)

    Pilipenko, Vladimir; Arnon, Shlomi

    2013-09-01

    In recent years the need for high data rate underwater wireless communication (WC) has increased. Nowadays, the conventional technology for underwater communication is acoustic. However, the maximum data rate that acoustic technology can provide is a few kilobits per second. On the other hand, emerging applications such as underwater imaging, networks of sensors and swarms of underwater vehicles require much faster data rates. As a result, underwater optical WC, which can provide much higher data rates, has been proposed as an alternative means of communication. In addition to high data rates, affordable communication systems become an important feature in the development requirements. The outcome of these requirements is a new system design based on off-the-shelf components such as blue and green light emitting diodes (LEDs). This is due to the fact that LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness. However, there are some challenges to be met when incorporating LEDs as part of the optical transmitter, such as low modulation rates and non linearity. In this paper, we review the main challenges facing the incorporation of LEDs as an integral part of underwater WC systems and propose some techniques to mitigate the LED limitations in order to achieve high data rate communication

  8. Augmenting the spectral efficiency of enhanced PAM-DMT-based optical wireless communications.

    PubMed

    Islim, Mohamed Sufyan; Haas, Harald

    2016-05-30

    The energy efficiency of pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) decreases as the modulation order of M-PAM modulation increases. Enhanced PAM-DMT (ePAM-DMT) was proposed as a solution to the reduced energy efficiency of PAM-DMT. This was achieved by allowing multiple streams of PAM-DMT to be superimposed and successively demodulated at the receiver side. In order to maintain a distortion-free unipolar ePAM-DMT system, the multiple time-domain PAM-DMT streams are required to be aligned. However, aligning the antisymmetry in ePAM-DMT is complex and results in efficiency losses. In this paper, a novel simplified method to apply the superposition modulation on M-PAM modulated discrete multitone (DMT) is introduced. Contrary to ePAM-DMT, the signal generation of the proposed system, termed augmented spectral efficiency discrete multitone (ASE-DMT), occurs in the frequency domain. This results in an improved spectral and energy efficiency. The analytical bit error rate (BER) performance bound of the proposed system is derived and compared with Monte-Carlo simulations. The system performance is shown to offer significant electrical and optical energy savings compared with ePAM-DMT and DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM). PMID:27410116

  9. The Holy Grail of quantum optical communication

    SciTech Connect

    García-Patrón, Raúl; Navarrete-Benlloch, Carlos; Lloyd, Seth; Shapiro, Jeffrey H.; Cerf, Nicolas J.

    2014-12-04

    Optical parametric amplifiers together with phase-shifters and beamsplitters have certainly been the most studied objects in the field of quantum optics. Despite such an intensive study, optical parametric amplifiers still keep secrets from us. We will show how they hold the answer to one of the oldest problems in quantum communication theory, namely the calculation of the optimal communication rate of optical channels.

  10. The Holy Grail of quantum optical communication

    NASA Astrophysics Data System (ADS)

    García-Patrón, Raúl; Navarrete-Benlloch, Carlos; Lloyd, Seth; Shapiro, Jeffrey H.; Cerf, Nicolas J.

    2014-12-01

    Optical parametric amplifiers together with phase-shifters and beamsplitters have certainly been the most studied objects in the field of quantum optics. Despite such an intensive study, optical parametric amplifiers still keep secrets from us. We will show how they hold the answer to one of the oldest problems in quantum communication theory, namely the calculation of the optimal communication rate of optical channels.

  11. Quantum Communication Experiments Over Optical Fiber

    NASA Astrophysics Data System (ADS)

    Takesue, Hiroki

    Quantum key distribution (QKD) is expected to be the first application of quantum information to be realized as a practical system. In the last decade, research on QKD made significant progress both in concept and technology. In this chapter, we review the progress of technologies designed to realize high-speed and long-distance quantum communication over optical fiber, focusing on the results obtained by NTT. The first section describes a roadmap towards scalable quantum communications, which is composed of three phases. The second section reviews our effort to realize phase 1 quantum communication systems, namely point-to-point QKD systems based on the differential phase shift QKD (DPS-QKD) protocol. The third section describes entanglement generation and application in the telecom band, which are the key technologies for realizing phase 2 and 3 systems. The final section provides a summary and describes the future outlook.

  12. Optical antenna in laser inter-satellite communication

    NASA Astrophysics Data System (ADS)

    Wen, Chuanhua; Wang, Chunxia; Li, Yuquan

    2005-02-01

    In the modern world of telecommunications, the concept of wireless global coverage is of the utmost importance. However, real global coverage can only be achieved by satellite systems. Satellites communication is the most important mean of the communication network. The traditional satellites communication and inter-satellites links are built by microwave. In recent years, laser links for inter-satellites communication are becoming more and more important. Laser communication systems operate in a frequency range above the regulated spectrum. Laser provides many advantages for using in point-to-point ISLs (inter-satellites links) such as for links between satellites and spacecraft in deep space. Such advantages include: high speed; high bandwidth; small antenna size; narrow field of view; and narrow antenna beam. These advantages combined with the advantages in fiber optic components (optical preamplifiers, multiplexers, detectors, etc) have made laser attractive for laser links. Now we can bring WDM (wavelength-division multiplexing) to emerging broadband satellite communication systems. By using the common antenna system and ATP (Aiming, Tracking and Pointing) system, the satellites will get more capacity. In the inter-satellites laser communication, the important performances of the systems such as BER and BL both have direct relation with the optical systems. The optical systems have the function of ATP. The optical antenna is the most important component of the optical system. So the optical antenna is an important key technology to the inter-satellites laser communication. In this paper, we mainly study the optical system in the inter-satellites laser communication. we compare with three kinds of optical antennas: refractor and reflector and Catadioptrics of the passive optical system; we also analyze the effect of bandwidth to the WDM communication systems; we use the correlative software, simulate the curves of the performance of the optical antennas. These

  13. Proposed new approach to design all optical AND gate using plasmonic based Mach-Zehnder interferometer for high speed communication

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Singh, Lokendra

    2016-04-01

    The limitation of conventional electronics is mitigated by all optical integrated circuits which have potential of high speed computing and information processing. In this work, an all optical AND gate using optical Kerr effect and optical bistability of a plasmonic based Mach-Zehnder interferometer (MZI) is proposed. An MZI is capable for switching of light according to the intensities of optical input signal. The paper constitutes with mathematical formulation of device and its study is verified using finite difference time domain (FDTD) method.

  14. Internet-Based Communication

    PubMed Central

    Gernsbacher, Morton Ann

    2015-01-01

    Google the question, “How is the Internet changing the way we communicate?,” and you will find no shortage of opinions, or fears, about the Internet altering the way we communicate. Although the Internet is not necessarily making communication briefer (neither is the Internet making communication less formal), the Internet is manifesting our preference for writing over speaking. I propose that our preference for communicating through Internet-based text derives from a fundamental feature of writing: In contrast to speech, which is most often synchronous, text is most often asynchronous. PMID:26330702

  15. Investigation of fluorine-doped tin oxide based optically transparent E-shaped patch antenna for terahertz communications

    SciTech Connect

    Anand, S. E-mail: darak.mayur@gmail.com Darak, Mayur Sudesh E-mail: darak.mayur@gmail.com Kumar, D. Sriram E-mail: darak.mayur@gmail.com

    2014-10-15

    In this paper, a fluorine-doped tin oxide based optically transparent E-shaped patch antenna is designed and its radiation performance is analyzed in the 705 – 804 GHz band. As optically transparent antennas can be mounted on optical display, they facilitate the reduction of overall system size. The proposed antenna design is simulated using electromagnetic solver - Ansys HFSS and its characteristics such as impedance bandwidth, directivity, radiation efficiency and gain are observed. Results show that the fluorine-doped tin oxide based optically transparent patch antenna overcomes the conventional patch antenna limitations and thus the same can be used for solar cell antenna used in satellite systems.

  16. Fiber Optic Communications Technology. A Status Report.

    ERIC Educational Resources Information Center

    Hull, Joseph A.

    Fiber optic communications (communications over very pure glass transmission channels of diameter comparable to a human hair) is an emerging technology which promises most improvements in communications capacity at reasonable cost. The fiber transmission system offers many desirable characteristics representing improvements over conventional…

  17. Integrated communications and optical navigation system

    NASA Astrophysics Data System (ADS)

    Mueller, J.; Pajer, G.; Paluszek, M.

    2013-12-01

    The Integrated Communications and Optical Navigation System (ICONS) is a flexible navigation system for spacecraft that does not require global positioning system (GPS) measurements. The navigation solution is computed using an Unscented Kalman Filter (UKF) that can accept any combination of range, range-rate, planet chord width, landmark, and angle measurements using any celestial object. Both absolute and relative orbit determination is supported. The UKF employs a full nonlinear dynamical model of the orbit including gravity models and disturbance models. The ICONS package also includes attitude determination algorithms using the UKF algorithm with the Inertial Measurement Unit (IMU). The IMU is used as the dynamical base for the attitude determination algorithms. This makes the sensor a more capable plug-in replacement for a star tracker, thus reducing the integration and test cost of adding this sensor to a spacecraft. Recent additions include an integrated optical communications system which adds communications, and integrated range and range rate measurement and timing. The paper includes test results from trajectories based on the NASA New Horizons spacecraft.

  18. Photosensitive terpolymer based on PFS:PFOA:GMA monomers for optical communications

    NASA Astrophysics Data System (ADS)

    Moujoud, Abderrafia; Kim, Hyun Jae; Andrews, Mark

    2008-11-01

    A photosensitive terpolymeric composition suitable for practical waveguide devices is provided. The terpolymer was produced from pentafluorostyrene (PFS), perfluoro-n-octyl acrylate (PFOA), and glycidyl methacrylate (GMA). We present a fabrication process where the device structure utilizes the same class of material for the core and cladding layers and it was fabricated without a plasma etching process. We also present simulation results that show good agreement with measured data and which thus permit to optimize the device performance. Based on the developed material and process; a 16-channel arrayed waveguide grating (AWG) multiplexer with excellent performance has been realized. The channel spacing of the multiplexer is 0.8 nm and operating around the 1550 nm wavelength. Together the developed material and process combine to produce AWG with an average insertion loss of 5 dB, the best channel shows an insertion loss of 4.7 dB; the uniformity of 1 dB, a crosstalk of less than -28 dB and a polarization dependence loss (PDL) of ~ 0.2 dB. During temperature cycling, a slight thickness hysteresis and refractive index hysteresis were observed above the glass transition temperature and is ascribed to the fact that the terpolymer material may not completely recover its elasticity in the heating/cooling cycle.

  19. Lessons Learnt from the Optical Communications Demonstrator (OCD)

    NASA Technical Reports Server (NTRS)

    Jeganathan, M.; Portillo, A.; Racho, C.; Lee, S.; Erickson, D.; DePew, J.; Monacos, S.; Biswas, A.

    1999-01-01

    The Optical Communications Demonstrator (OCD) is a laboratory based lasercom terminal that was developed to validate several key technologies such as precision beam pointing, high bandwidth beacon tracking and beacon acquisition.

  20. Performance Analysis and Electronics Packaging of the Optical Communications Demonstrator

    NASA Technical Reports Server (NTRS)

    Jeganathan, M.; Monacos, S.

    1998-01-01

    The Optical Communications Demonstrator (OCD), under development at the Jet Propulsion Laboratory (JPL), is a laboratory-based lasercomm terminal designed to validate several key technologies, primarily precision beam pointing, high bandwidth tracking, and beacon acquisition.

  1. Self-homodyne free-space optical communication system based on orthogonally polarized binary phase shift keying.

    PubMed

    Cai, Guangyu; Sun, Jianfeng; Li, Guangyuan; Zhang, Guo; Xu, Mengmeng; Zhang, Bo; Yue, Chaolei; Liu, Liren

    2016-06-10

    A self-homodyne laser communication system based on orthogonally polarized binary phase shift keying is demonstrated. The working principles of this method and the structure of a transceiver are described using theoretical calculations. Moreover, the signal-to-noise ratio, sensitivity, and bit error rate are analyzed for the amplifier-noise-limited case. The reported experiment validates the feasibility of the proposed method and demonstrates its advantageous sensitivity as a self-homodyne communication system. PMID:27409006

  2. The atmosphere of Mars and optical communications

    NASA Technical Reports Server (NTRS)

    Annis, J.

    1987-01-01

    The effects of the Martian atmosphere on an optical communication link are analyzed using Mariner 9, Viking Orbiter, and Viking Lander data. Clouds are found to have minimal effect because of their scarcity and thinness. Dust (from dust storms) has the dominant impact on opacity. However, periods of reduced visibility are infrequent and more closely resemble the effects of thin clouds on the earth. A simple argument is presented which suggests that the Martian atmosphere has fewer turbulence related effects (i.e., Mars has better resolution, lower image wander, and less scintillation) than the best of the earth's ground based locations.

  3. Advanced Sensors Boost Optical Communication, Imaging

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Brooklyn, New York-based Amplification Technologies Inc. (ATI), employed Phase I and II SBIR funding from NASA s Jet Propulsion Laboratory to forward the company's solid-state photomultiplier technology. Under the SBIR, ATI developed a small, energy-efficient, extremely high-gain sensor capable of detecting light down to single photons in the near infrared wavelength range. The company has commercialized this technology in the form of its NIRDAPD photomultiplier, ideal for use in free space optical communications, lidar and ladar, night vision goggles, and other light sensing applications.

  4. A Geosynchronous Orbit Optical Communications Relay Architecture

    NASA Technical Reports Server (NTRS)

    Edwards, Bernard L.; Israel, David J.

    2014-01-01

    NASA is planning to fly a Next Generation Tracking and Data Relay Satellite (TDRS) next decade. While the requirements and architecture for that satellite are unknown at this time, NASA is investing in communications technologies that could be deployed on the satellite to provide new communications services. One of those new technologies is optical communications. The Laser Communications Relay Demonstration (LCRD) project, scheduled for launch in December 2017 as a hosted payload on a commercial communications satellite, is a critical pathfinder towards NASA providing optical communications services on the Next Generation TDRS. While it is obvious that a small to medium sized optical communications terminal could be flown on a GEO satellite to provide support to Near Earth missions, it is also possible to deploy a large terminal on the satellite to support Deep Space missions. Onboard data processing and Delay Tolerant Networking (DTN) are two additional technologies that could be used to optimize optical communications link services and enable additional mission and network operations. This paper provides a possible architecture for the optical communications augmentation of a Next Generation TDRS and touches on the critical technology work currently being done at NASA. It will also describe the impact of clouds on such an architecture and possible mitigation techniques.

  5. Full-duplex optical communication system

    NASA Technical Reports Server (NTRS)

    Shay, Thomas M. (Inventor); Hazzard, David A. (Inventor); Horan, Stephen (Inventor); Payne, Jason A. (Inventor)

    2004-01-01

    A method of full-duplex electromagnetic communication wherein a pair of data modulation formats are selected for the forward and return data links respectively such that the forward data electro-magnetic beam serves as a carrier for the return data. A method of encoding optical information is used wherein right-hand and left-hand circular polarizations are assigned to optical information to represent binary states. An application for an earth to low earth orbit optical communications system is presented which implements the full-duplex communication and circular polarization keying modulation format.

  6. Implementation of wavelength selector based on electro-optic effect in Mach-Zehnder interferometers for high speed communications

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Bisht, Ashish; Singh, Gurdeep; Choudhary, Kuldeep; Sharma, Divya

    2015-09-01

    The design of 4×1 and 8×1 wavelength selectors have been presented with complete functionality and configuration, which can be used as DWDM components in optical networks. The proposed optical logic unit is based on electro-optic effect in Mach-Zehnder interferometer (MZI). The Mach-Zehnder interferometer (MZI) structures collectively show the powerful capability in switching an input optical signal to a desired output port from a collection of output ports. A strategy for optical wavelength switching has been shown by constructing a design of wavelength selector using MZIs. The paper constitutes the mathematical description of proposed device and thereafter the wavelength switching behavior is analyzed using beam propagation method (BPM). The results are also verified with the help of MATLAB simulations and truth table.

  7. Dual-channel chaos synchronization and communication based on unidirectionally coupled VCSELs with polarization-rotated optical feedback and polarization-rotated optical injection.

    PubMed

    Liu, Jiao; Wu, Zheng-Mao; Xia, Guang-Qiong

    2009-07-20

    A novel dual-channel chaotic synchronization configuration is proposed. This system is constructed on the basis of two unidirectionally coupled vertical-cavity surface-emitting lasers (VCSELs), where a VCSEL subjected to polarization-rotated optical feedback is used as a transmitter and the other VCSEL subjected to polarization-rotated optical injection is used as a receiver. The synchronization and communication performances of such a system are numerically investigated. The results show that, similar to polarization-preserved coupled system with polarization-preserved optical feedback at the T-VCSEL port and polarization-preserved optical injection at the R-VCSEL port, such polarization-rotated coupled system can also realize complete synchronization between each pair of linear polarization (LP) modes and the total output of T-VCSEL and R-VCSEL. Compared with the polarization-preserved coupled system, this proposed system has higher tolerance to mismatched parameters. Furthermore, the average intensities of two orthogonal LP modes are almost the same so that this framework may be used to realize dual-channel chaos communication. Under the additive chaos modulation (ACM) encryption scheme, the encoded messages can be successfully extracted for both of orthogonal LP modes. PMID:19654666

  8. Prediction of optical communication link availability: real-time observation of cloud patterns using a ground-based thermal infrared camera

    NASA Astrophysics Data System (ADS)

    Bertin, Clément; Cros, Sylvain; Saint-Antonin, Laurent; Schmutz, Nicolas

    2015-10-01

    The growing demand for high-speed broadband communications with low orbital or geostationary satellites is a major challenge. Using an optical link at 1.55 μm is an advantageous solution which potentially can increase the satellite throughput by a factor 10. Nevertheless, cloud cover is an obstacle for this optical frequency. Such communication requires an innovative management system to optimize the optical link availability between a satellite and several Optical Ground Stations (OGS). The Saint-Exupery Technological Research Institute (France) leads the project ALBS (French acronym for BroadBand Satellite Access). This initiative involving small and medium enterprises, industrial groups and research institutions specialized in aeronautics and space industries, is currently developing various solutions to increase the telecommunication satellite bandwidth. This paper presents the development of a preliminary prediction system preventing the cloud blockage of an optical link between a satellite and a given OGS. An infrared thermal camera continuously observes (night and day) the sky vault. Cloud patterns are observed and classified several times a minute. The impact of the detected clouds on the optical beam (obstruction or not) is determined by the retrieval of the cloud optical depth at the wavelength of communication. This retrieval is based on realistic cloud-modelling on libRadtran. Then, using subsequent images, cloud speed and trajectory are estimated. Cloud blockage over an OGS can then be forecast up to 30 minutes ahead. With this information, the preparation of the new link between the satellite and another OGS under a clear sky can be prepared before the link breaks due to cloud blockage.

  9. Optical networks for earth-space communications and their performance

    NASA Astrophysics Data System (ADS)

    Shaik, Kamran S.; Wonica, Dennis; Wilhelm, Michael D.

    1994-08-01

    This article describes optical subnets of ground based receiving stations for earth-space optical communications. The optical subnet concepts presented here provide full line-of-sight coverage of the ecliptic, 24 hours a day, with high weather availability. The technical characteristics of the optical station and the user terminal are presented as well as the effects of cloud cover, transmittance through the atmosphere, and impact of background noise for day or night time operation upon the communication link. In addition, candidate geographic sites are identified, and a link design for a hypothetical Pluto mission in 2015 is included.

  10. MC-CDMA for optical wireless communications

    NASA Astrophysics Data System (ADS)

    Luan, Yingzi; Jiang, Guang; Li, Jiandong

    2005-11-01

    MC-CDMA is a spectrum-efficient modulation in RF systems. Here it is used in optical wireless communications. Performance is simulated by using multiuser detection. Spatial Diversity is also considered and analyzed.

  11. On the quantum-channel capacity for orbital angular momentum-based free-space optical communications.

    PubMed

    Zhang, Yequn; Djordjevic, Ivan B; Gao, Xin

    2012-08-01

    Inspired by recent demonstrations of orbital angular momentum-(OAM)-based single-photon communications, we propose two quantum-channel models: (i) the multidimensional quantum-key distribution model and (ii) the quantum teleportation model. Both models employ operator-sum representation for Kraus operators derived from OAM eigenkets transition probabilities. These models are highly important for future development of quantum-error correction schemes to extend the transmission distance and improve date rates of OAM quantum communications. By using these models, we calculate corresponding quantum-channel capacities in the presence of atmospheric turbulence. PMID:22859154

  12. A Fibre-Optic Communications Network for Teaching Clinical Medicine.

    ERIC Educational Resources Information Center

    Williams, Robin

    1985-01-01

    Describes an interactive television system based on fiber-optic communications technology which is used to facilitate participation by University of London medical students in lecture/tutorials by teachers in different hospital locations. Highlights include advantages of fiber-optics, cable manufacture and installation, opto-electronic interface,…

  13. Four-Mode Squeezing For Optical Communications

    NASA Technical Reports Server (NTRS)

    Schumaker, Bonny L.

    1989-01-01

    Experiments demonstrated potential of four-mode squeezing for increasing immunity to noise in fiber-optical communication systems and interferometric devices. Four-mode squeezing reduces quantum noise more than ordinary squeezing and provides partial immunity to non-quantum-mechanical phase noise arising in such media as optical fibers.

  14. Atmospheric propagation issues relevant to optical communications

    NASA Technical Reports Server (NTRS)

    Churnside, James H.; Shaik, Kamran

    1989-01-01

    Atmospheric propagation issues relevant to space-to-ground optical communications for near-earth applications are studied. Propagation effects, current optical communication activities, potential applications, and communication techniques are surveyed. It is concluded that a direct-detection space-to-ground link using redundant receiver sites and temporal encoding is likely to be employed to transmit earth-sensing satellite data to the ground some time in the future. Low-level, long-term studies of link availability, fading statistics, and turbulence climatology are recommended to support this type of application.

  15. Study of optimum methods of optical communication

    NASA Technical Reports Server (NTRS)

    Harger, R. O.

    1972-01-01

    Optimum methods of optical communication accounting for the effects of the turbulent atmosphere and quantum mechanics, both by the semi-classical method and the full-fledged quantum theoretical model are described. A concerted effort to apply the techniques of communication theory to the novel problems of optical communication by a careful study of realistic models and their statistical descriptions, the finding of appropriate optimum structures and the calculation of their performance and, insofar as possible, comparing them to conventional and other suboptimal systems are discussed. In this unified way the bounds on performance and the structure of optimum communication systems for transmission of information, imaging, tracking, and estimation can be determined for optical channels.

  16. Hybrid RF / Optical Communication Terminal with Spherical Primary Optics for Optical Reception

    NASA Technical Reports Server (NTRS)

    Charles, Jeffrey R.; Hoppe, Daniel H.; Sehic, Asim

    2011-01-01

    Future deep space communications are likely to employ not only the existing RF uplink and downlink, but also a high capacity optical downlink. The Jet Propulsion Laboratory (JPL) is currently investigating the benefits of a ground based hybrid RF and deep space optical terminal based on limited modification of existing 34 meter antenna designs. The ideal design would include as large an optical aperture as technically practical and cost effective, cause minimal impact to RF performance, and remain cost effective even when compared to a separate optical terminal of comparable size. Numerous trades and architectures have been considered, including shared RF and optical apertures having aspheric optics and means to separate RF and optical signals, plus, partitioned apertures in which various zones of the primary are dedicated to optical reception. A design based on the latter is emphasized in this paper, employing spherical primary optics and a new version of a "clamshell" corrector that is optimized to fit within the limited space between the antenna sub-reflector and the existing apex structure that supports the subreflector. The mechanical design of the hybrid accommodates multiple spherical primary mirror panels in the central 11 meters of the antenna, and integrates the clamshell corrector and optical receiver modules with antenna hardware using existing attach points to the maximum extent practical. When an optical collection area is implemented on a new antenna, it is possible to design the antenna structure to accommodate the additional weight of optical mirrors providing an equivalent aperture of several meters diameter. The focus of our near term effort is to use optics with the 34 meter DSS-13 antenna at Goldstone to demonstrate spatial optical acquisition and tracking capability using an optical system that is temporarily integrated into the antenna.

  17. Novel Subcarrier Multiplexing Technologies for Optical Communication

    NASA Astrophysics Data System (ADS)

    Wang, Xiaolu

    Microwave subcarrier multiplexing (SCM) has recently emerged as a potentially important multiplexing technique for wideband lightwave systems. By using a double beam modulation technique (DBM), in which the information is modulated onto an optical coherent pair instead of a single optical beam, a novel SCM system is proposed. The system, with multi-division and multi-channel capability (encompassing the multiplexing of both multi-channel analog and/or digital signals), potentially has an information bandwidth (IBW) of tens of GHz and is particularly suitable for optical fiber and free-space communications. The principle of the proposed system was first demonstrated by using a standing-wave surface-acoustic -wave optical modulator (SWSAW). The modulator was fabricated on the top of a Ti - LiNbO_3 waveguide. The highest acoustic modulation frequency achieved was 300 MHz, which corresponds to a 600 MHz subcarrier. The laser output, which had been directly modulated by VHF TV signals, passed through the SWSAW modulator and was upconverted to the UHF band. The carrier-to-noise ratio of the upconverted TV signal was measured to be 30 dB. The more advanced way of implementing the proposed SCM is utilizing a frequency-locked-laser (FLL) pair, which has virtually no upper frequency limitation and is readily FM modulated. We have demonstrated, to our knowledge, the first FM modulated FLL pair for optical communication. The subcarrier (locked) frequency of 15 GHz is also believed to be the highest reported today. The multi-channel video signals and high frequency sinusoidal modulations up to 1 GHz, after being FM modulated onto and demodulated from a 15 GHz subcarrier, are displayed directly on standard TV receivers and oscilloscopes. Another novel SCM, with ultra high millimeter -wave frequency subcarriers of up to one hundred GHz, based upon the self-sustained-pulsation (SSP) of the laser diode, was also proposed. A preliminary optical link test with multi

  18. Power efficient optical communications for space applications

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.

    1982-01-01

    Optical communications technology promises substantial size, weight and power consumption savings for space to space high data rate communications over presently used microwave technology. These benefits are further increased by making the most efficient use of the available optical signal energy. This presentation will describe the progress to date on a project to design, build and demonstrate in the laboratory an optical communication system capable of conveying 2.5 bits of information per effective received photon. Such high power efficiencies will reduce the need for photon collection at the receiver and will greatly reduce the requirements for optical pointing accuracy, both at the transmitter as well as the receiver. A longer range program to demonstrate even higher photon efficiencies will also be described.

  19. Time domain zero-padding based adaptive-PAM signal transmission with high spectral efficiency in IMDD optical communication system

    NASA Astrophysics Data System (ADS)

    Zhang, Fangliu; He, Jing; Deng, Rui; Cheng, Yun; Xiao, Minlei; Chen, Lin

    2016-08-01

    In this paper, an adaptive pulse amplitude modulation (APAM) scheme is proposed and experimentally demonstrated in the intensity-modulation and direct-detection (IMDD) optical communications system. In the proposed scheme, the channel is divided into two sub-channels, and different PAM mapping can be chosen for different sub-channel according to the fading conditions. In addition, the 20-km standard single mode fiber (SSMF) transmission of 24 Gbit/s 16/4-APAM signal with the spectral efficiency (SE) up to 6 bit/s/Hz is experimentally demonstrated. The experiment results show that the bit error rate (BER) of the 16/4-APAM signal can be achieved less than 2.4e-2.

  20. Hybrid optical radio frequency airborne communications

    NASA Astrophysics Data System (ADS)

    Bagley, Zachary C.; Hughes, David H.; Juarez, Juan C.; Kolodzy, Paul; Martin, Todd; Northcott, Malcolm; Pike, H. Alan; Plasson, Ned D.; Stadler, Brian; Stotts, Larry B.; Young, David W.

    2012-05-01

    Optical RF Communications Adjunct Program flight test results provide validation of the theoretical models and hybrid optical radio frequency (RF) airborne system concepts developed by the Defense Advanced Research Projects Agency and the U.S. Air Force Research Laboratory. Theoretical models of the free-space optical communications (FSOC), RF, and network components accurately predict the flight test results under a wide range of day and night operating conditions. The FSOC system, including the adaptive optics and optical modem, can operate under high turbulence conditions. The RF and network mechanisms of Layer 2 retransmission and failover provide increased reliability, reducing end-to-end packet error rates. Overall the test results show that stable, long-range FSOC is possible and practical for near-term operations.

  1. Communications satellites versus fiber optics

    NASA Astrophysics Data System (ADS)

    Goldman, A. M., Jr.

    Examples of the interfaces encountered in the provision of intercity, long-distance service in the U.S. are examined, and a comparison is conducted of the costs of the Intercity, Long-Distance portion of a single voice circuit derived from either fixed satellite trunking service or fiber optic bulk capacity. It is estimated that by the end of 1988, fiber optic should span the nation connecting New York and Washington with Los Angeles and San Francisco. It is shown that once fiber connects a given pair of cities, it becomes the least costly transmission medium, especially compared to fixed satellite service. Attention is given to equivalent transmission capacities, six providers of fiber optic capacity, a total satellite capacity comparison, an economic lifetime comparison, satellite and fiber optic network maps, satellite city-pair distance and cost matrices, and fiber optic city-pair distance matrices. It is pointed out that certain future CONUS satellite service applications will be inherently invulnerable to terrestrial fiber optics serving fixed routes.

  2. Enhanced performance of 400 Gb/s DML-based CAP systems using optical filtering technique for short reach communication.

    PubMed

    Tao, Li; Wang, Yiguang; Xiao, Jiangnan; Chi, Nan

    2014-12-01

    A parallel transmission approach is more likely to realize 400 Gb/s and above short reach transmission as it helps to reduce the cost of both electrical and optical device largely. Directly modulated lasers (DML) are more attractive in 400 Gb/s approach, because it requires relatively small amount of driving power and has low insertion loss, thus lowering its cost. However, the intrinsic chirp will degrade the transmission performance. In this paper, an optical filtering technique is introduced for 400 Gb/s high-speed DML-based carrierless amplitude and phase (CAP) modulation short reach systems for the first time. Owing to the additional optical filter, 1 dB and 3.6 dB sensitivity improvement at BER of 3.8 x 10(-3) is obtained for the back-to-back and 15 km fiber link transmission for single lane at the bitrate of 28 Gb/s. Then a 16-lane CAP16 system with a total bit rate of 413 Gb/s is demonstrated experimentally using low-cost 10 GHz-class DML using optical filtering technique. PMID:25606867

  3. Enhanced quantum communication via optical refocusing

    NASA Astrophysics Data System (ADS)

    Lupo, Cosmo; Giovannetti, Vittorio; Pirandola, Stefano; Mancini, Stefano; Lloyd, Seth

    2011-07-01

    We consider the problem of quantum communication mediated by a passive optical refocusing system. The model captures the basic features of all those situations in which a signal is either refocused by a repeater for long-distance communication, or it is focused on a detector prior to the information decoding process. Introducing a general method for linear passive optical systems, we determine the conditions under which optical refocusing implies information transmission gain. Although the finite aperture of the repeater may cause loss of information, we show that the presence of the refocusing system can substantially enhance the rate of reliable communication with respect to the free-space propagation. We explicitly address the transferring of classical messages over the quantum channel, but the results can be easily extended to include the case of transferring quantum messages as well.

  4. Ground-to-Ground Optical Communications Demonstration

    NASA Technical Reports Server (NTRS)

    Biswas, A.; Lee, S.

    2000-01-01

    A bidirectional horizontal-path optical link was demonstrated between Strawberry Peak (SP), Lake Arrowhead, California, and the JPL Table Mountain Facility (TMF), Wrightwood, California, during June and November of 1998. The 0.6-m telescope at TMF was used to broadcast a 4-beam 780-nm beacon to SP. The JPL-patented Optical Communications Demonstrator (OCD) at SP received the beacon, performed ne tracking to compensate for the atmosphere-induced beacon motion and retransmitted a 844-nm communications laser beam modulated at 40 to 500 Mb/s back to TMF. Characteristics of the horizontal-path atmospheric channel as well as performance of the optical communications link were evaluated. The normalized variance of the irradiance fluctuations or scintillation index delta2/I at either end was determined. At TMF where a single 844-nm beam was received by a 0.6-m aperture, the measured delta2/I covered a wide range from 0.07 to 1.08. A single 780-nm beam delta2/I measured at SP using a 0.09-m aperture yielded values ranging from 0.66 to 1.03, while a combination of four beams reduced the scintillation index due to incoherent averaging to 0.22 to 0.40. This reduction reduced the dynamic range of the fluctuations from 17 to 21 dB to 13 to 14 dB as compared with the OCD tracking sensor dynamic range of 10 dB. Predictions of these values also were made based on existing theories and are compared. Generally speaking, the theoretical bounds were reasonable. Discussions on the probability density function (PDF) of the intensity fluctuations are presented and compared with the measurements made. The lognormal PDF was found to agree for the weak scintillation regime as expected. The present measurements support evidence presented by earlier measurements made using the same horizontal path, which suggests that the aperture averaging effect is better than theoretically predicted.

  5. Structured-light-assisted wireless digital optical communications

    NASA Astrophysics Data System (ADS)

    Long, Yunfei; Wang, Shuaijun; Wu, Wei; Yang, Xiaomin; Jeon, Gwanggil; Liu, Kai

    2015-11-01

    Camera-projector-pair-based digital optical communications are attractive for safe and flexible usages, while the state-of-the-art systems suffer from various disadvantages or distortions of communication channels, including the irregularity and the non-uniform albedo of projection surfaces, the radial distortion of optical lenses, etc. In this paper, we present a novel method for digital optical communications. Assisted by structured light illumination, we overcome those disadvantages and accurately derive the models of the communication channels. First, by deriving accurate model-free coordinates maps for the camera-projector pair, we overcome the issues caused by the irregularity of projection surfaces and the radial distortion of optical lenses. Second, by normalizing received digital optical signals with calibrated system parameters, we overcome the issue arising from the non-uniform albedo of projection surfaces. Thus, with the models and all pixel-wise operations, we finally achieve robust and real-time wireless digital optical communications. Experimental results verify the validity of the proposed method.

  6. Simplified Optics and Controls for Laser Communications

    NASA Technical Reports Server (NTRS)

    Chen, Chien-Chung; Hemmati, Hamid

    2006-01-01

    A document discusses an architecture of a spaceborne laser communication system that provides for a simplified control subsystem that stabilizes the line of sight in a desired direction. Heretofore, a typical design for a spaceborne laser communication system has called for a high-bandwidth control loop, a steering mirror and associated optics, and a fast steering-mirror actuator to stabilize the line of sight in the presence of vibrations. In the present architecture, the need for this fast steering-mirror subsystem is eliminated by mounting the laser-communication optics on a disturbance-free platform (DFP) that suppresses coupling of vibrations to the optics by 60 dB. Taking advantage of microgravitation, in the DFP, the optical assembly is free-flying relative to the rest of the spacecraft, and a low-spring-constant pointing control subsystem exerts small forces to regulate the position and orientation of the optics via voice coils. All steering is effected via the DFP, which can be controlled in all six degrees of freedom relative to the spacecraft. A second control loop, closed around a position sensor and the spacecraft attitude-control system, moves the spacecraft as needed to prevent mechanical contact with the optical assembly.

  7. A novel decoding algorithm based on the hierarchical reliable strategy for SCG-LDPC codes in optical communications

    NASA Astrophysics Data System (ADS)

    Yuan, Jian-guo; Tong, Qing-zhen; Huang, Sheng; Wang, Yong

    2013-11-01

    An effective hierarchical reliable belief propagation (HRBP) decoding algorithm is proposed according to the structural characteristics of systematically constructed Gallager low-density parity-check (SCG-LDPC) codes. The novel decoding algorithm combines the layered iteration with the reliability judgment, and can greatly reduce the number of the variable nodes involved in the subsequent iteration process and accelerate the convergence rate. The result of simulation for SCG-LDPC(3969,3720) code shows that the novel HRBP decoding algorithm can greatly reduce the computing amount at the condition of ensuring the performance compared with the traditional belief propagation (BP) algorithm. The bit error rate (BER) of the HRBP algorithm is considerable at the threshold value of 15, but in the subsequent iteration process, the number of the variable nodes for the HRBP algorithm can be reduced by about 70% at the high signal-to-noise ratio (SNR) compared with the BP algorithm. When the threshold value is further increased, the HRBP algorithm will gradually degenerate into the layered-BP algorithm, but at the BER of 10-7 and the maximal iteration number of 30, the net coding gain (NCG) of the HRBP algorithm is 0.2 dB more than that of the BP algorithm, and the average iteration times can be reduced by about 40% at the high SNR. Therefore, the novel HRBP decoding algorithm is more suitable for optical communication systems.

  8. Adaptive Detector Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    2000-01-01

    The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

  9. An optical communication link on the Shuttle

    NASA Astrophysics Data System (ADS)

    Grady, Jane L.

    A communication link for the transfer of data between the crew cabin and payload bay of the Shuttle is proposed. The configuration of the system, which is to transmit data optically through the Shuttle cabin window, is described. The effects of temperature cycling and cosmic radiation on optical fibers, the cable, connectors, and lenses, and of vibrations during a mission on the alignment of collimating lenses at the window are investigated. Consideration is given to determining the optimum design for the optical fiber and the optimum system operation wavelength for transmission through the aft Orbiter window and the payload environment.

  10. Fiber optic communication in borehole applications

    SciTech Connect

    Franco, R.J.; Morgan, J.R.

    1997-04-01

    The Telemetry Technology Development Department have, in support of the Advanced Geophysical Technology Department and the Oil Recovery Technology Partnership, developed a fiber optic communication capability for use in borehole applications. This environment requires the use of packaging and component technologies to operate at high temperature (up to 175{degrees}C) and survive rugged handling. Fiber optic wireline technology has been developed by The Rochester Corporation under contract to Sandia National Labs and produced a very rugged, versatile wireline cable. This development has utilized commercial fiber optic component technologies and demonstrated their utility in extreme operating environments.

  11. The effects of turbulent aberrations on an optical communication system based on orbital angular momentum-carrying beams

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-xin; Xu, Jian-cai; Wang, Jian-yu; Jia, Jian-jun

    2009-07-01

    A photon communication system based on orbital angular momentum (OAM)-carrying beams is studied. We compartmentalize the atmospheric aberration into tilt,coma, astigmatism as well as defous. We numerically analyze the effects of tilt on the orbital angular momentum of communication beams and find that the tilt aberration can induce the noisy OAM. With the increasing of parameters P, L, the probability of initial OAM goes down while the effective number of noise OAM increases. At the same time, the peaks of the induced OAM probability (max-probability) are different as the P, L, changes. The increase of zenith angle damages the probability and leads to noisy OAM. This can also be applied to the impact of refractive index structure parameter. We also numerically analyze the effects which receiving-radius puts on the receiving probability of initial OAM through tilt aberration. Under the influence of tilt, the receiving probability of previous orbital angular momentum slashs with the receiving-radius becoming large.

  12. Compact Deep-Space Optical Communications Transceiver

    NASA Technical Reports Server (NTRS)

    Roberts, W. Thomas; Charles, Jeffrey R.

    2009-01-01

    Deep space optical communication transceivers must be very efficient receivers and transmitters of optical communication signals. For deep space missions, communication systems require high performance well beyond the scope of mere power efficiency, demanding maximum performance in relation to the precious and limited mass, volume, and power allocated. This paper describes the opto-mechanical design of a compact, efficient, functional brassboard deep space transceiver that is capable of achieving megabyte-per-second rates at Mars ranges. The special features embodied to enhance the system operability and functionality, and to reduce the mass and volume of the system are detailed. System tests and performance characteristics are described in detail. Finally, lessons learned in the implementation of the brassboard design and suggestions for improvements appropriate for a flight prototype are covered.

  13. Space Optical Communications Using Laser Beam Amplification

    NASA Technical Reports Server (NTRS)

    Agrawal, Govind

    2015-01-01

    The Space Optical Communications Using Laser Beam Amplification (SOCLBA) project will provide a capability to amplify a laser beam that is received in a modulating retro-reflector (MRR) located in a satellite in low Earth orbit. It will also improve the pointing procedure between Earth and spacecraft terminals. The technology uses laser arrays to strengthen the reflected laser beam from the spacecraft. The results of first year's work (2014) show amplification factors of 60 times the power of the signal beam. MMRs are mirrors that reflect light beams back to the source. In space optical communications, a high-powered laser interrogator beam is directed from the ground to a satellite. Within the satellite, the beam is redirected back to ground using the MMR. In the MMR, the beam passes through modulators, which encode a data signal onto the returning beam. MMRs can be used in small spacecraft for optical communications. The SOCLBA project is significant to NASA and small spacecraft due to its application to CubeSats for optical data transmission to ground stations, as well as possible application to spacecraft for optical data transmission.

  14. Free space optical communications: coming of age

    NASA Astrophysics Data System (ADS)

    Stotts, Larry B.; Stadler, Brian; Lee, Gary

    2008-04-01

    Information superiority, where for the military or business, is the decisive advantage of the 21st Century. While business enjoys the information advantage of robust, high-bandwidth fiber optic connectivity that heavily leverages installed commercial infrastructure and service providers, mobile military forces need the wireless equivalent to leverage that advantage. In other words, an ability to deploy anywhere on the globe and maintain a robust, reliable communications and connectivity infrastructure, equivalent to that enjoyed by a CONUS commercial user, will provide US forces with information superiority. Assured high-data-rate connectivity to the tactical user is the biggest gap in developing and truly exploiting the potential of the information superiority weapon. Though information superiority is much discussed and its potential is well understood, a robust communications network available to the lowest military echelons is not yet an integral part of the force structure, although high data rate RF communications relays, e.g., Tactical Common Data Link, and low data SATCOM, e.g, Ku Spread Spectrum, are deployed and used by the military. This may change with recent advances in laser communications technologies created by the fiber optic communications revolution. This paper will provide a high level overview of the various laser communications programs conducted over the last 30 plus years, and proposed efforts to get these systems finally deployed.

  15. Space Based Communications

    NASA Technical Reports Server (NTRS)

    Simpson, James; Denson, Erik; Valencia, Lisa; Birr, Richard

    2003-01-01

    Current space lift launches on the Eastern and Western Range require extensive ground-based real-time tracking, communications and command/control systems. These are expensive to maintain and operate and cover only limited geographical areas. Future spaceports will require new technologies to provide greater launch and landing opportunities, support simultaneous missions, and offer enhanced decision support models and simulation capabilities. These ranges must also have lower costs and reduced complexity while continuing to provide unsurpassed safety to the public, flight crew, personnel, vehicles and facilities. Commercial and government space-based assets for tracking and communications offer many attractive possibilities to help achieve these goals. This paper describes two NASA proof-of-concept projects that seek-to exploit the advantages of a space-based range: Iridium Flight Modem and Space-Based Telemetry and Range Safety (STARS). Iridium Flight Modem uses the commercial satellite system Iridium for extremely low cost, low rate two-way communications and has been successfully tested on four aircraft flights. A sister project at Goddard Space Flight Center's (GSFC) Wallops Flight Facility (WFF) using the Globalstar system has been tested on one rocket. The basic Iridium Flight Modem system consists of a L1 carrier Coarse/Acquisition (C/A)-Code Global Positioning System (GPS) receiver, an on-board computer, and a standard commercial satellite modem and antennas. STARS uses the much higher data rate NASA owned Tracking and Data Relay Satellite System (TDRSS), a C/A-Code GPS receiver, an experimental low-power transceiver, custom built command and data handler processor, and digitized flight termination system (FTS) commands. STARS is scheduled to fly on an F-15 at Dryden Flight Research Center in the spring of 2003, with follow-on tests over the next several years.

  16. The design of space optical communications terminal with high efficient

    NASA Astrophysics Data System (ADS)

    Deng, Xiaoguo; Li, Gang; Jiang, Bo; Yang, Xiaoxu; Yan, Peipei

    2015-02-01

    In order to improve high-speed laser space optical communications terminal receive energy and emission energy, meet the demand of mini-type and light-type for space-based bear platform, based on multiple-reflect coaxial optical receiving antenna structure, while considering the installation difficulty, a high-efficient optical system had been designed, which aperture is off-axial, both signal-receiving sub-optical system and emission sub-optical system share a same primary optical path. By the separating light lens behind the primary optical path, the received light with little energy will be filtered and shaped and then transmitted to each detector, at the same time, by the coupling element, the high-power laser will be coupling into optical antenna, and then emitted to outside. Applied the power-detected optical system evaluate principle, the optimized off-axial optical system's efficiency had been compared with the coaxial optical system. While, analyzed the Gauss beam energy distribution by numerical theory, discussed that whether off-axis optical system can be an emission terminal, verify the feasibility of the theory of the design of the system.

  17. Some theoretical results in variable-rate optical communications.

    NASA Technical Reports Server (NTRS)

    Levitt, B. K.

    1972-01-01

    Review of several variable-rate optical transmission schemes over an earth-to-space link which neutralize the effects of atmospheric turbulence. These adaptive laser communication systems exploit atmospheric reciprocity and the relatively long coherence time of the turbulence to monitor the time-varying state of the earth-to-space channel by using a satellite beacon and making appropriate measurements at the ground terminal. Optimal variable-rate strategy based on this channel-state information results is considerably improved performance in comparison with nonadaptive optical communication systems.

  18. Design and performance of a repeater for optical satellite communication

    NASA Astrophysics Data System (ADS)

    Ohm, G.; Wiesmann, Th.; Hieber, E.

    General design aspects of optical inter-satellite and inter-orbit links and the choice of technology for data relay applications are described. A first step toward optical links is the ESA in-orbit experiment SILEX which is briefly reviewed with emphasis on the communication subsystem. All relevant equipments of the communication subsystem, which is based on 0.85-micron laser diodes, QPPM data format, and direct detection, have been developed and tested. Using the equipment developed, an experimental repeater was assembled and investigated. Measured and simulated results are in close agreement, and no major critical events occurred during the development and test activities.

  19. Internet-Based Communication

    ERIC Educational Resources Information Center

    Gernsbacher, Morton Ann

    2014-01-01

    Google the question, "How is the Internet changing the way we communicate?," and you will find no shortage of opinions, or fears, about the Internet altering the way we communicate. Although the Internet is not necessarily making communication briefer (neither is the Internet making communication less formal), the Internet is manifesting…

  20. Application of semiconductor optical amplifier for mobile radio communications networks based on radio-over-fiber systems

    NASA Astrophysics Data System (ADS)

    Andreev, Vladimir A.; Burdin, Vladimir A.; Volkov, Kirill A.; Dashkov, Michael V.; Bukashkin, Sergei A.; Buzov, Alexander L.; Procopiev, Vladimir I.; Zharkov, Alexander D.

    2016-03-01

    The analysis of semiconductor optical amplifier applications in Radio-over-Fiber systems of telecommunication networks is given. In such systems semiconductor optical amplifier can be used for either amplification, modulation or detection, and also as an universal device.

  1. Satellite-Based Quantum Communications

    SciTech Connect

    Hughes, Richard J; Nordholt, Jane E; McCabe, Kevin P; Newell, Raymond T; Peterson, Charles G

    2010-09-20

    Single-photon quantum communications (QC) offers the attractive feature of 'future proof', forward security rooted in the laws of quantum physics. Ground based quantum key distribution (QKD) experiments in optical fiber have attained transmission ranges in excess of 200km, but for larger distances we proposed a methodology for satellite-based QC. Over the past decade we have devised solutions to the technical challenges to satellite-to-ground QC, and we now have a clear concept for how space-based QC could be performed and potentially utilized within a trusted QKD network architecture. Functioning as a trusted QKD node, a QC satellite ('QC-sat') could deliver secret keys to the key stores of ground-based trusted QKD network nodes, to each of which multiple users are connected by optical fiber or free-space QC. A QC-sat could thereby extend quantum-secured connectivity to geographically disjoint domains, separated by continental or inter-continental distances. In this paper we describe our system concept that makes QC feasible with low-earth orbit (LEO) QC-sats (200-km-2,000-km altitude orbits), and the results of link modeling of expected performance. Using the architecture that we have developed, LEO satellite-to-ground QKD will be feasible with secret bit yields of several hundred 256-bit AES keys per contact. With multiple ground sites separated by {approx} 100km, mitigation of cloudiness over any single ground site would be possible, potentially allowing multiple contact opportunities each day. The essential next step is an experimental QC-sat. A number of LEO-platforms would be suitable, ranging from a dedicated, three-axis stabilized small satellite, to a secondary experiment on an imaging satellite. to the ISS. With one or more QC-sats, low-latency quantum-secured communications could then be provided to ground-based users on a global scale. Air-to-ground QC would also be possible.

  2. Precision pointing mechanism for intersatellite optical communication

    NASA Astrophysics Data System (ADS)

    Hicks, T.; O'Sullivan, B.; Russell, J.; Scholl, L.

    1989-09-01

    The SILEX project is an experimental communication system aimed at demonstrating, in orbit, the feasibility of intersatellite optical communications using semiconductor lasers. As part of this project, a precision mechanism has been developed to point the transmitted beam ahead of the current receiving satellite position. This is necessary due to the relative motion of the satellites, the narrow beam, and the finite velocity of light. The design and construction of a prototype of this device is discussed along with measurements of performance. The technique as described can be used in many applications requiring precision beam steering or rotation control.

  3. Optical communication with semiconductor laser diode

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic; Sun, X.

    1989-01-01

    This interim report describes the progress in the construction of a 220 Mbps Q=4 PPM optical communication system that uses a semiconductor laser as the optical transmitter and an avalanche photodiode (APD) as the photodetector. The transmitter electronics have been completed and contain both GaAs and ECL III IC's. The circuit was able to operate at a source binary data rate from 75 Mbps to 290 Mbps with pulse rise and fall times of 400 ps. The pulse shapes of the laser diode and the response from the APD/preamplifier module were also measured.

  4. Airborne Visible Laser Optical Communications (AVLOC) experiment

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A series of optical communication experiments between a high altitude aircraft at 18.3 km (60,000 ft) and a ground station were conducted by NASA from summer 1972 through winter 1973. The basic system was an optical tracker and transmitter located in each terminal. The aircraft transceiver consisted of a 5-mW HeNe laser transmitter with a 30-megabit modulator. The ground station beacon was an argon laser operating at 488 nm. A separate pulsed laser radar was used for initial acquisition. The objective of the experiment was to obtain engineering data on the precision tracking and communication system performance at both terminals. Atmospheric effects on the system performance was also an experiment objective. The system description, engineering analysis, testing, and flight results are discussed.

  5. Airborne visible laser optical communication experiment.

    NASA Technical Reports Server (NTRS)

    Randall, J. L.

    1972-01-01

    A series of optical communication experiments between a high altitude aircraft at 18.3 km (60,000 ft) and a ground station are planned by NASA in the summer of 1972. The basic concept is that an optical tracker and transmitter will be located in each terminal. The aircraft transceiver consists of a 5-mW HeNe laser transmitter with a 30-megabit modulator. The ground station beacon is an argon laser operating at 488 nm. A separate pulsed laser radar is used for initial acquisition. The objective of the experiment is to obtain engineering data on the precision tracking and communication system performance at both terminals. Atmospheric effects on the system performance are of prime importance.

  6. Optical communication noise rejection using corelated photons

    NASA Technical Reports Server (NTRS)

    Jackson, D.; Hockney, G. M.; Dowling, J. P.

    2002-01-01

    This paper describes a completely new way to perform noise rejection using photons correlated through quantum entanglement to improve an optical communications link in the presence of uncorrelated noise. In particular, a detailed analysis is made of the case where a classical link would be saturated by an intense background, such as when a satellite is in front of the sun, and identifies where the quantum correlating system has superior performance.

  7. Optical transceiver platform for laser communication experiments

    NASA Astrophysics Data System (ADS)

    Coffelt, Everett L.; Ebben, Thomas H.

    1986-01-01

    This paper describes a laser communication (lasercom) transceiver platform to be used for laboratory experiments. The platform features a directly modulated semiconductor laser, avalanche photodiode receiver, and microprocessor-controlled acquisition and tracking system. The platform provides a test-bed, enabling study in vital areas of lasercom hardware such as system performance versus link distance, optical power, tracking accuracy, and subsystem and component characterization for future system specifications, including critical areas limiting present system performance.

  8. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  9. Software design of optical link for indoor wireless optical communication network used LEDs as source visible light communication

    NASA Astrophysics Data System (ADS)

    Liner, Andrej; Papes, Martin; Jaros, Jakub; Koudelka, Petr; Latal, Jan; Vitasek, Jan; Hajek, Lukas; Vasinek, Vladimir

    2015-01-01

    Nowadays, the conventional light sources are replaced progressively evolving LED (Light Emitting Diode) for their deficient properties. This technology recorded dynamic growth mainly due to effective research in increasing power density and choice the color shade on good color rendering CRI (Color Rendering Index). This extending the zone of used LEDs. Development of lighting technology by means of white power LEDs provided impulse to the idea of the development of optical wireless data networks based on optical radiation in the visible region of the spectrum VLC (Visible Light Communications). In the last years being recorded a turnover of research from transmission of information via optical fiber to the transmission of information through wireless networks. At the same time the concept of information transmission by indirect sight between transmitter and receiver NLOS (Non Line of Sight) is changing. Line of research focuses mainly on the direct line of sight LOS (Line of Sight). This is due to the development of the semiconductor lighting through the white power LED. This is connected with the idea of using them as a transmitter for communication purposes. This article deals with software design of optical link for indoor wireless optical network in LightTools software. Optimal optical source was designed for communication using LED as the first. For the proposed type of LEDs sources were used different shapes and distances distribution between LEDs in a single cell at the designed optical transmitter.

  10. Research and Development in Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith

    2004-01-01

    A report in the form of lecture slides summarizes the optical-communications program of NASA s Jet Propulsion Laboratory (JPL) and describes the JPL Optical Communications Telescope Laboratory (OCTL) and its role in the program. The purpose of the program is to develop equipment and techniques for laser communication between (1) ground stations and (2) spacecraft (both near Earth and in deep space) and aircraft. The OCTL is an astronomical- style telescope facility that includes a 1-m-diameter, 75.8-m-focal length telescope in an elevation/azimuth mount, plus optical and electronic subsystems for tracking spacecraft and aircraft, receiving laser signals from such moving targets, and transmitting high-power laser signals to such targets. Near-term research at the OCTL is expected to focus on mitigating the effects of atmospheric scintillation on uplinks and on beacon-assisted tracking of ground stations by stations in deep space. Near-term experiments are expected to be performed with retroreflector-equipped aircraft and Earth-orbiting spacecraft techniques to test mathematical models of propagation of laser beams, multiple-beam strategies to mitigate uplink scintillation, and pointing and tracking accuracy of the telescope.

  11. Integrated Formation Optical Communication and Estimation System

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Kuhnert, Andreas; Kovalik, Joseph; Hadaegh, Fred; Shaddock, Daniel

    2008-01-01

    An architecture has been designed that integrates formation estimation methodologies, precision formation sensing, and high-bandwidth formation communication into a robust, strap-on system that meets knowledge and communication requirements for the majority of planned, precision formation missions. Specifically, the integrated system supports (a) sub-millimeter metrology, (b) multiple greater than 10 Mbps communication channels over a large, 10 deg field-of-view (FOV), and (c) generalized formation estimation methodologies. The sensing sub-system consists of several absolute, metrology gauges with up to 0.1 mm precision that use amplitude-modulated lasers and a LISA-heritage phase meter. Since amplitude modulation is used, inexpensive and robust diode lasers may be used instead of complex, frequency-stabilized lasers such as for nanometer-level metrology. The metrology subsystem laser transceivers consist of a laser diode, collecting optics, and an avalanche photo diode (APD) for detecting incoming laser signals. The APD is necessary since received power is small due to the large (for optical applications) FOV. The phase meter determines the phase of the incoming amplitude modulations as measured by the APD. This phase is equivalent to time-of-flight and, therefore, distance. By placing three laser transceivers on each spacecraft, 18 clock-offset-corrupted distances are calculated. These measurements are communicated and averaged to obtain nine correct distances between the transceivers. From these correct distances, the range and bearing between spacecraft and their relative attitude are determined. Next, communication is integrated on the laser carrier through spectral separation. Metrology amplitude modulations are limited to the 45-50 MHz band, leaving 0-45 MHz for communication. Through careful design of coding scheme, error correction, and filters, six independent 10 Mbps receive channels are possible. Hence, a spacecraft can simultaneously broadcast at 10

  12. Ultrafast all-optical technologies for bidirectional optical wireless communications.

    PubMed

    Jin, Xian; Hristovski, Blago A; Collier, Christopher M; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F

    2015-04-01

    In this Letter, a spherical retro-modulator architecture is introduced for operation as a bidirectional transceiver in passive optical wireless communication links. The architecture uses spherical retroreflection to enable retroreflection with broad directionality (2π steradians), and it uses all-optical beam interaction to enable modulation on ultrafast timescales (120 fs duration). The spherical retro-modulator is investigated from a theoretical standpoint and is fabricated for testing with three glasses, N-BK7, N-LASF9, and S-LAH79. It is found that the S-LAH79 structure provides the optimal refraction and nonlinearity for the desired retroreflection and modulation capabilities. PMID:25831390

  13. Electronic polarization-division demultiplexing based on digital signal processing in intensity-modulation direct-detection optical communication systems.

    PubMed

    Kikuchi, Kazuro

    2014-01-27

    We propose a novel configuration of optical receivers for intensity-modulation direct-detection (IM · DD) systems, which can cope with dual-polarization (DP) optical signals electrically. Using a Stokes analyzer and a newly-developed digital signal-processing (DSP) algorithm, we can achieve polarization tracking and demultiplexing in the digital domain after direct detection. Simulation results show that the power penalty stemming from digital polarization manipulations is negligibly small. PMID:24515206

  14. Development of the free-space optical communications analysis software

    NASA Astrophysics Data System (ADS)

    Jeganathan, Muthu; Mecherle, G. Stephen; Lesh, James R.

    1998-05-01

    The Free-space Optical Communication Analysis Software (FOCAS) was developed at the Jet Propulsion Laboratory (JPL) to provide mission planners, systems engineers and communications engineers with an easy to use tool to analyze direct-detection optical communication links. The FOCAS program, implemented in Microsoft Excel, gives it all the power and flexibility built into the spreadsheet. An easy-to-use interface, developed using Visual Basic for Applications (VBA), to the spreadsheet allows easy input of data and parameters. A host of pre- defined components allow an analyst to configure a link without having to know the details of the components. FOCAS replaces the over-a-decade-old FORTRAN program called OPTI widely used previously at JPL. This paper describes the features and capabilities of the Excel-spreadsheet-based FOCAS program.

  15. Spherical transceivers for ultrafast optical wireless communications

    NASA Astrophysics Data System (ADS)

    Jin, Xian; Hristovski, Blago A.; Collier, Christopher M.; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F.

    2016-02-01

    Optical wireless communications (OWC) offers the potential for high-speed and mobile operation in indoor networks. Such OWC systems often employ a fixed transmitter grid and mobile transceivers, with the mobile transceivers carrying out bi-directional communication via active downlinks (ideally with high-speed signal detection) and passive uplinks (ideally with broad angular retroreflection and high-speed modulation). It can be challenging to integrate all of these bidirectional communication capabilities within the mobile transceivers, however, as there is a simultaneous desire for compact packaging. With this in mind, the work presented here introduces a new form of transceiver for bi-directional OWC systems. The transceiver incorporates radial photoconductive switches (for high-speed signal detection) and a spherical retro-modulator (for broad angular retroreflection and high-speed all-optical modulation). All-optical retromodulation are investigated by way of theoretical models and experimental testing, for spherical retro-modulators comprised of three glasses, N-BK7, N-LASF9, and S-LAH79, having differing levels of refraction and nonlinearity. It is found that the spherical retro-modulator comprised of S-LAH79, with a refractive index of n ≍ 2 and a Kerr nonlinear index of n2 ≍ (1.8 ± 0.1) × 10-15 cm2/W, yields both broad angular retroreflection (over a solid angle of 2π steradians) and ultrafast modulation (over a duration of 120 fs). Such transceivers can become important elements for all-optical implementations in future bi-directional OWC systems.

  16. The aero optics effect on near space laser communication optical system

    NASA Astrophysics Data System (ADS)

    Hu, Yuan; Fu, Yuegang; Jiang, Huilin

    2013-08-01

    With the developing of the space laser communication link, the performance index including higher transfer speed, extending transfer distance, and environmental adaptability, all ask the system accuracy and indexes improving. Special the developing near space platform, its environmental is extremes, the near space drone and other airplane flight speed is very quickly from the subsonic to supersonic. The aero optics effect caused by high speed will generate a thin turbulent air layer. It affects the performance of laser communication optical system by laser light vibration, deviation and so on, further more affects the performance of laser communication system working performance, even can't communication. Therefore, for achieving optical system indexes, we need do more research in optical system near space aero optics environmental adaptability. In this paper, near space link environmental characteristic are researched. And on the base of the aero optics theory, computer simulating method is applied to analyze the relationship among the altitude, the flight speed and the image dispersion. The result shows that, the aero optics effect cannot be ignored when the terminal is in low altitude or is moving with supersonic speed. The effect must be taken into considered from overall design. The result will provide the basis of research design.

  17. Panoramic alignment system for optical wireless communication systems

    NASA Astrophysics Data System (ADS)

    Shen, Thomas C.; Drost, Robert J.; Rzasa, John; Sadler, Brian M.; Davis, Christopher C.

    2015-03-01

    Free space optical communication may provide a viable adjunct to radio frequency (RF) technology for mobile communications, especially in "RF-denied" settings in which RF-based communication may be prohibited or impractical. These settings may include military tactical environments or settings which suffer from RF jamming or interference. Unlike many RF communication systems, point-to-point optical communications between mobile nodes typically require establishing and maintaining alignment, which requires each node to have awareness of the locations of neighboring nodes. We propose a method to create this situational awareness between nodes using purely optical means. This method uses a camera that is focused on a hyperboloidal mirror, thus providing a 360-degree view of the surrounding environment. The camera and mirror are used to detect light emitted from the beacon transmitters from neighboring nodes, with the location of the beacon image in the sensor plane of the camera yielding elevation and azimuth information of the beacon. The beacon transmitter itself is modulated, allowing it to be distinguished from the environment. In discussing our experimental realization of this system, we assess its performance.

  18. ALMA communication backbone in Chile goes optical

    NASA Astrophysics Data System (ADS)

    Filippi, G.; Ibsen, J.; Jaque, Sandra; Liello, F.; Navarro, C.

    2014-07-01

    High-bandwidth communication has become a key factor for scientific installations as Observatories. This paper describes the technical, organizational, and operational goals and the level of completion of the ALMA Optical Link Project. The project focus is the creation and operation of an effective and sustainable communication infrastructure to connect the ALMA Observatory, located in the Atacama Desert, in the Northern region of Chile, with the point of presence in ANTOFAGASTA, about 400km away, of the EVALSO infrastructure, and from there to the Central Office in the Chilean capital, Santiago. This new infrastructure that will be operated in behalf of ALMA by REUNA, the Chilean National Research and Education Network, will use state of the art technologies, like dark fiber from newly built cables and DWDM transmission, allowing extending the reach of high capacity communication to the remote region where the Observatory is located. When completed, the end-to-end Gigabit-per-second (Gbps) capable link will provide ALMA with a modern, effective, robust, communication infrastructure capable to cope with present and future demands, like those coming from fast growing data transfer to rapid response mode, from remote monitoring and engineering to virtual presence.

  19. Modeling of optical wireless scattering communication channels over broad spectra.

    PubMed

    Liu, Weihao; Zou, Difan; Xu, Zhengyuan

    2015-03-01

    The air molecules and suspended aerosols help to build non-line-of-sight (NLOS) optical scattering communication links using carriers from near infrared to visible light and ultraviolet bands. This paper proposes channel models over such broad spectra. Wavelength dependent Rayleigh and Mie scattering and absorption coefficients of particles are analytically obtained first. They are applied to the ray tracing based Monte Carlo method, which models the photon scattering angle from the scatterer and propagation distance between two consecutive scatterers. Communication link path loss is studied under different operation conditions, including visibility, particle density, wavelength, and communication range. It is observed that optimum communication performances exist across the wavelength under specific atmospheric conditions. Infrared, visible light and ultraviolet bands show their respective features as conditions vary. PMID:26366662

  20. Vision communications based on LED array and imaging sensor

    NASA Astrophysics Data System (ADS)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  1. Fundamentals of Free-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Dolinar, Sam; Moision, Bruce; Erkmen, Baris

    2012-01-01

    Free-space optical communication systems potentially gain many dBs over RF systems. There is no upper limit on the theoretically achievable photon efficiency when the system is quantum-noise-limited: a) Intensity modulations plus photon counting can achieve arbitrarily high photon efficiency, but with sub-optimal spectral efficiency. b) Quantum-ideal number states can achieve the ultimate capacity in the limit of perfect transmissivity. Appropriate error correction codes are needed to communicate reliably near the capacity limits. Poisson-modeled noises, detector losses, and atmospheric effects must all be accounted for: a) Theoretical models are used to analyze performance degradations. b) Mitigation strategies derived from this analysis are applied to minimize these degradations.

  2. A Coarse Pointing Assembly for Optical Communication

    NASA Technical Reports Server (NTRS)

    Szekely, G.; Blum, D.; Humphries, M.; Koller, A.; Mussett, D.; Schuler, S.; Vogt, P.

    2010-01-01

    In the framework of a contract with the European Space Agency, RUAG Space are developing a Coarse Pointing Assembly for an Optical Communication Terminal with the goal to enable high-bandwidth data exchange between GEO and/or LEO satellites as well as to earth-bound ground stations. This paper describes some development and testing aspects of such a high precision opto-mechanical device, with emphasis on the influence of requirements on the final design, the usage of a Bearing Active Preload System, some of the lessons learned on the BAPS implementation, the selection of a flex print design as rotary harness and some aspects of functional and environmental testing.

  3. Optical Alignment Device For Laser Communication

    NASA Technical Reports Server (NTRS)

    Casey, William L.

    1988-01-01

    Optical alignment device under development enables continuous tracking and coalignment of two beams of light. Intended primarily for laser-communication station, in which transmitted beam must be aligned with received beam to ensure transmitted beam falls on receiver at other station. Expected to consume less power and be smaller and less complicated than alignment shutter and drive previously used. Prism and filter separate two overlapping collimated light beams of different wavelength or polarization. Coordinates of two beams tracked on charge-coupled device to determine degree of directional misalignment between two beams.

  4. Vibration-induced jitter control in satellite optical communication

    NASA Astrophysics Data System (ADS)

    Xue, Zheng-yan; Qi, Bo; Ren, Ge

    2013-08-01

    Laser satellite communication has become especially attractive in recent years. However, because the laser beam is very narrow and there is a long distance between satellites, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause optical jitter, leading to the reduction of received signals and bit-error rate degradation. Consequently, optical jitter control with PAT (pointing acquisition and tracking) subsystems is a critical problem in laser satellite communication. To compensate for the platform vibration effectively in realtime, in this paper, an adaptive feedback control technique based on Youla-parameterization is presented, which can adapt to the current disturbance acting on the laser beam by adjusting its parameters in realtime to maintain optimal performance. The main idea is to use the well-known Youla parameterization formula to construct a feedback control scheme with the guaranteed closed loop stability, and the feedback controller is a function of plant coprime factors and a free parameter Q. For adaptive disturbance estimation, the free parameter Q is set to an adaptive finite impulse response (FIR) filter, the coefficients of which are updated by a recursive least-squares (RLS) algorithm in realtime. It is shown in experiment that the adaptive feedback control technique based on Youla-parameterization can reject the optical jitter caused by satellite platform vibration effectively and improve the performance of the system.

  5. Evidence-based Science Communication

    NASA Astrophysics Data System (ADS)

    Kahan, D.

    2012-12-01

    This presentation will describe a concrete strategy for bridging the gap between the *science* of science communication and the practice of it. In recent years, social scientists have made substantial progress in identifying the psychological influences that shape public receptivity to scientific information relating to climate change and other public policy issues. That work, however, has consisted nearly entirely of laboratory experiments and public opinion surveys; these methods identify general mechanisms of information processing but do not yield concrete prescriptions for communication in field settings. In order to integrate the findings of the science of science communication with the practice of it, field communication must now be made into a meaningful site of science communication research. "Evidence-based science communication" will involve collaborative work between social scientists and practitioners aimed at formulating and testing scientifically informed communication strategies in real-world contexts.

  6. Fiber optical parametric amplifiers in optical communication systems

    PubMed Central

    Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

  7. Enhanced Faraday effect and its application to optical communication.

    PubMed

    Bomke, H A; Harmatz, M

    1977-03-01

    This paper shows that the enhanced Faraday effect of optical resonance lines can be applied to optical communication. A secure optical communication system was designed and successfully tested. It used the integrated enhanced Faraday effect at low fields to produce polarization modulation and the high dispersion of the enhanced effect at high fields to scramble and unscramble the transmitted messages. PMID:20168574

  8. Adaptive optics for daytime deep space laser communications to Mars

    NASA Technical Reports Server (NTRS)

    Wilson, Keith E.; Wright, Malcolm; Lee, Shinkhak; Troy, Mitchell

    2005-01-01

    This paper describes JPL research in adaptive optics (AO) to reduce the daytime background noise on a Mars-to-Earth optical communications link. AO can reduce atmosphere-induced wavefront aberrations, and enable single mode receiver operation thereby buying back margin in the deep space optical communications link.

  9. Optical Communications Performance with Realistic Weather and Automated Repeat Query

    NASA Astrophysics Data System (ADS)

    Clare, L.; Miles, G.; Breidenthal, J.

    2016-05-01

    Deep-space optical communications are subject to outages arising from deterministic clear line-of-sight dynamics as well as unpredictable weather effects at the ground station. These effects can be mitigated using buffering and automatic retransmission techniques. We provide an analysis that incorporates a realistic weather model based on a two-state Markov chain. Performance for a hypothetical Mars 2022 optical mission is derived incorporating dynamics over an entire 728-day synodic cycle, during which link passes and link data rate vary. Buffer sizing is addressed and operational implications are identified. Also, buffer occupancy results are extended for deep-space missions spanning a range of link data rates.

  10. Laser Beam Steering/shaping for Free Space Optical Communication

    NASA Technical Reports Server (NTRS)

    Wang, Xinghua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John; Miranda, Felix; McManamon, Paul F.

    2004-01-01

    The 2-D Optical Phased Array (OPA) antenna based on a Liquid Crystal On Silicon (LCoS) device can be considered for use in free space optical communication as an active beam controlling device. Several examples of the functionality of the device include: beam steering in the horizontal and elevation direction; high resolution wavefront compensation in a large telescope; and beam shaping with the computer generated kinoform. Various issues related to the diffraction efficiency, steering range, steering accuracy as well as the magnitude of wavefront compensation are discussed.

  11. Solar background effects in wireless optical communications

    NASA Astrophysics Data System (ADS)

    Sidorovich, Vladimir G.

    2002-12-01

    In free-space optical (FSO) communications, conditions may be met when laser links suffer from solar background radiation (SBR). There are four types of such conditions Direct sunlight hitting a photodetector Reflected sunlight (glints) Sunlight scattered by hydrometeors Sunlight scattered by surrounding objects (walls, etc.) Direct sunlight may cause total break of communications (link outage), and thus affect the link availability. However, experiments prove that the sunlight does not cause irreversible degradation of semiconductor photodetectors used in FSO systems. Estimations are made of the link outage periods duration for various types of SBR conditions, also other effects caused by SBR have been considered. Recommendations are presented for the link directivity optimization to avoid (or to minimize the probability of) communication interrupts caused by SBR. A nomographic chart has been developed to forecast periods of time when direct or scattered solar radiation may cause link outage. With this chart, a user in any point of the globe, knowing the link orientation (azimuth and elevation angles), can see when and for how long (if at all) may the link operation be affected by unfavorable SBR conditions, also in many cases it is possible to recommend insignificant modifications in the link orientation causing material improvement in FSO system performance.

  12. The status of optical communications at NASA/JPL

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    2001-01-01

    Future NASA and commercial space missions will require communications terminals to provide higher data rate with lower mass and power. Optical communications is a rapidly developing technology in response to this demand.

  13. Status of Free-Space Optical Communications at JPL

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    2000-01-01

    Optical communications is a rapidly developing technology applicable to future NASA and commercial space missions that desire a communications terminal that provides a higher data rate with lower mass and power.

  14. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    NASA Astrophysics Data System (ADS)

    Gómez Colín, R.; García Juárez, A.; Zaldívar Huerta, I. E.; Marquina, A. Vera; García Delgado, L. A.; Leal Cruz, A. L.; Gómez Fuentes, R.

    2016-03-01

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade.

  15. Optical ground station site diversity for Deep Space Optical Communications the Mars Telecom Orbiter optical link

    NASA Technical Reports Server (NTRS)

    Wilson, K.; Parvin, B.; Fugate, R.; Kervin, P.; Zingales, S.

    2003-01-01

    Future NASA deep space missions will fly advanced high resolution imaging instruments that will require high bandwidth links to return the huge data volumes generated by these instruments. Optical communications is a key technology for returning these large data volumes from deep space probes. Yet to cost effectively realize the high bandwidth potential of the optical link will require deployment of ground receivers in diverse locations to provide high link availability. A recent analysis of GOES weather satellite data showed that a network of ground stations located in Hawaii and the Southwest continental US can provide an average of 90% availability for the deep space optical link. JPL and AFRL are exploring the use of large telescopes in Hawaii, California, and Albuquerque to support the Mars Telesat laser communications demonstration. Designed to demonstrate multi-Mbps communications from Mars, the mission will investigate key operational strategies of future deep space optical communications network.

  16. Robust free-space optical communication for indoor information environment

    NASA Astrophysics Data System (ADS)

    Nakada, Toyohisa; Itoh, Hideo; Kunifuji, Susumu; Nakashima, Hideyuki

    2003-10-01

    The purpose of our study is to establish a robust communication, while keeping security and privacy, between a handheld communicator and the surrounding information environment. From the viewpoint of low power consumption, we have been developing a reflectivity modulating communication module composed of a liquid crystal light modulator and a corner-reflecting mirror sheet. We installed a corner-reflecting sheet instead of light scattering sheet in a handheld videogame machine with a display screen with a reflection-type liquid crystal. Infrared (IR) LED illuminator attached next to the IR camera of a base station illuminates all the room, and the terminal send their data to the base station by switching ON and OFF of the reflected IR beam. Intensity of reflected light differs with the position and the direction of the terminal, and sometimes the intensity of OFF signal at a certain condition is brighter than that of ON signal at another condition. To improve the communication quality, use of machine learning technique is a possibility of the solution. In this paper, we compare various machine learning techniques for the purpose of free space optical communication, and propose a new algorithm that improves the robustness of the data link. Evaluation using an actual free-space communication system is also described.

  17. CMOS-compatible graphene photodetector covering all optical communication bands

    NASA Astrophysics Data System (ADS)

    Pospischil, Andreas; Humer, Markus; Furchi, Marco M.; Bachmann, Dominic; Guider, Romain; Fromherz, Thomas; Mueller, Thomas

    2013-11-01

    Optical interconnects are becoming attractive alternatives to electrical wiring in intra- and interchip communication links. Particularly, the integration with silicon complementary metal-oxide semiconductor (CMOS) technology has received considerable interest because of the ability of cost-effective integration of electronics and optics on a single chip. Although silicon enables the realization of optical waveguides and passive components, the integration of another, optically absorbing, material is required for photodetection. Traditionally, germanium or compound semiconductors are used for this purpose; however, their integration with silicon technology faces major challenges. Recently, graphene emerged as a viable alternative for optoelectronic applications, including photodetection. Here, we demonstrate an ultra-wideband CMOS-compatible photodetector based on graphene. We achieved a multigigahertz operation over all fibre-optic telecommunication bands beyond the wavelength range of strained germanium photodetectors, the responsivity of which is limited by their bandgap. Our work complements the recent demonstration of a CMOS-integrated graphene electro-optical modulator, and paves the way for carbon-based optical interconnects.

  18. Advancing Unmanned Aircraft Sensor Collection and Communication Capabilities with Optical Communications

    NASA Astrophysics Data System (ADS)

    Lukaczyk, T.

    2015-12-01

    Unmanned aircraft systems (UAS) are now being used for monitoring climate change over both land and seas. Their uses include monitoring of cloud conditions and atmospheric composition of chemicals and aerosols due to pollution, dust storms, fires, volcanic activity and air-sea fluxes. Additional studies of carbon flux are important for various ecosystem studies of both marine and terrestrial environments specifically, and can be related to climate change dynamics. Many measurements are becoming more complex as additional sensors become small enough to operate on more widely available small UAS. These include interferometric radars as well as scanning and fan-beam lidar systems which produce data streams even greater than those of high resolution video. These can be used to precisely map surfaces of the earth, ocean or ice features that are important for a variety of earth system studies. As these additional sensor capabilities are added to UAS the ability to transmit data back to ground or ship monitoring sites is limited by traditional wireless communication protocols. We describe results of tests of optical communication systems that provide significantly greater communication bandwidths for UAS, and discuss both the bandwidth and effective range of these systems, as well as their power and weight requirements both for systems on UAS, as well as those of ground-based receiver stations. We justify our additional use of Delay and Disruption Tolerant Networking (DTN) communication protocols with optical communication methods to ensure security and continuity of command and control operations. Finally, we discuss the implications for receiving, geo-referencing, archiving and displaying data streams from sensors communicated via optical communication to better enable real-time anomaly detection and adaptive sampling capabilities using multiple UAS or other unmanned or manned systems.

  19. Quantum Limits of Space-to-Ground Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Dolinar, S.

    2012-01-01

    Quantum limiting factors contributed by the transmitter, the optical channel, and the receiver of a space-to-ground optical communications link are described. Approaches to move toward the ultimate quantum limit are discussed.

  20. Performance of indoor optical femtocell by visible light communication

    NASA Astrophysics Data System (ADS)

    Cui, Kaiyun; Quan, Jinguo; Xu, Zhengyuan

    2013-07-01

    Femotocell has been proposed and deployed to improve the indoor coverage and capacity of a cellular network. One big challenge in its deployment is the interference between the macrocell and femtocell cellular networks. In this paper we propose a new physical layer for the implementation of indoor femtocells - optical femtocells by LED-based visible light communication. A general system structure of the indoor optical femtocell network is first introduced. A combined wavelength division and code division multiple access scheme is proposed to differentiate cells and multiple users within a cell. This scheme coupled with directional beaming characteristics of the LEDs helps to mitigate intercell interference and intracell inference. The communication performance adopting the dimming compatible variable-PPM modulation suggested by the IEEE standard is analyzed. Monte-Carlo simulation is then carried out to reveal the system performance numerically under typical system settings and effects of various parameters.

  1. Quantifying Atmospheric Impacts on Space Optical Imaging and Communications

    NASA Astrophysics Data System (ADS)

    Alliss, R.; Felton, B.

    2011-09-01

    Clouds and optical turbulence are key drivers in the performance of optical imaging and communication systems. Clouds are composed of liquid water and/or ice crystals and depending on the physical thickness can produce atmospheric fades easily exceeding 10 dB. In these more common cases, impacts on optical imaging and communication systems may be severe. On the other hand, there are times when cloud fades may be as low as 1 or 2 dB as a result of thin, ice crystal based cirrus clouds. In these cases, the impacts on imaging and communication collectors may be limited. Atmospheric optical turbulence acts to distort light in the atmosphere, degrading imagery from telescopes. The quality of service of a free space optical communications link may also be impacted. Some of the degradation due to turbulence can be corrected by adaptive optics. However, the severity of optical turbulence, and thus the amount of correction required, is largely dependent upon distributions of turbulence at the location of interest. Large variations in the Fried Coherence Length (ro) are common as a function of time of day and by location and can range from just a few centimeters to tens of centimeters. The ability to characterize the distribution and frequency of clouds and optical turbulence are critical in order to understand and predict atmospheric impacts. A state-of-the-art cloud detection system has been developed, validated and applied to produce high resolution climatologies in order to investigate these impacts. The cloud detection system uses global in coverage, geostationary, multi-spectral satellite imagery at horizontal resolutions up to one kilometer and temporal resolutions up to fifteen minutes. Multi-spectral imagery from the visible wavelengths (0.6 μm) through the longwave infrared (15 μm) are used to produce individual cloud tests which are combined to produce a composite cloud analysis. The basis for the detection algorithm relies on accurate modeling of the clear sky

  2. LDPC-PPM Coding Scheme for Optical Communication

    NASA Technical Reports Server (NTRS)

    Barsoum, Maged; Moision, Bruce; Divsalar, Dariush; Fitz, Michael

    2009-01-01

    In a proposed coding-and-modulation/demodulation-and-decoding scheme for a free-space optical communication system, an error-correcting code of the low-density parity-check (LDPC) type would be concatenated with a modulation code that consists of a mapping of bits to pulse-position-modulation (PPM) symbols. Hence, the scheme is denoted LDPC-PPM. This scheme could be considered a competitor of a related prior scheme in which an outer convolutional error-correcting code is concatenated with an interleaving operation, a bit-accumulation operation, and a PPM inner code. Both the prior and present schemes can be characterized as serially concatenated pulse-position modulation (SCPPM) coding schemes. Figure 1 represents a free-space optical communication system based on either the present LDPC-PPM scheme or the prior SCPPM scheme. At the transmitting terminal, the original data (u) are processed by an encoder into blocks of bits (a), and the encoded data are mapped to PPM of an optical signal (c). For the purpose of design and analysis, the optical channel in which the PPM signal propagates is modeled as a Poisson point process. At the receiving terminal, the arriving optical signal (y) is demodulated to obtain an estimate (a^) of the coded data, which is then processed by a decoder to obtain an estimate (u^) of the original data.

  3. Japanese first optical interorbit communications engineering satellite (OICETS)

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akio; Hori, Toshihiro; Shimizu, Takafumi; Nakagawa, Keizo

    1994-09-01

    The National Space Development Agency of Japan (NASDA) plans to conduct an optical inter-orbit ling experiment in cooperation with the European Space Agency (ESA). ESA will launch the ARTEMIS geostationary satellite equipped with the SILEX optical terminal. NASDA will launch the Optical Inter-orbit Communications Engineering Test Satellite (OICETS) equipped with the LUCE optical inter-orbit communications equipment into low earth orbit. The link experiment will be conducted between these satellites with associated ground equipment in Europe and Japan.

  4. Mitigating Photon Jitter in Optical PPM Communication

    NASA Technical Reports Server (NTRS)

    Moision, Bruce

    2008-01-01

    A theoretical analysis of photon-arrival jitter in an optical pulse-position-modulation (PPM) communication channel has been performed, and now constitutes the basis of a methodology for designing receivers to compensate so that errors attributable to photon-arrival jitter would be minimized or nearly minimized. Photon-arrival jitter is an uncertainty in the estimated time of arrival of a photon relative to the boundaries of a PPM time slot. Photon-arrival jitter is attributable to two main causes: (1) receiver synchronization error [error in the receiver operation of partitioning time into PPM slots] and (2) random delay between the time of arrival of a photon at a detector and the generation, by the detector circuitry, of a pulse in response to the photon. For channels with sufficiently long time slots, photon-arrival jitter is negligible. However, as durations of PPM time slots are reduced in efforts to increase throughputs of optical PPM communication channels, photon-arrival jitter becomes a significant source of error, leading to significant degradation of performance if not taken into account in design. For the purpose of the analysis, a receiver was assumed to operate in a photon- starved regime, in which photon counts follow a Poisson distribution. The analysis included derivation of exact equations for symbol likelihoods in the presence of photon-arrival jitter. These equations describe what is well known in the art as a matched filter for a channel containing Gaussian noise. These equations would yield an optimum receiver if they could be implemented in practice. Because the exact equations may be too complex to implement in practice, approximations that would yield suboptimal receivers were also derived.

  5. High-power diode lasers for optical communications applications

    NASA Technical Reports Server (NTRS)

    Carlin, D. B.; Goldstein, B.; Channin, D. J.

    1985-01-01

    High-power, single-mode, double-heterojunction AlGaAs diode lasers are being developed to meet source requirements for both fiber optic local area network and free space communications systems. An individual device, based on the channeled-substrate-planar (CSP) structure, has yielded single spatial and longitudinal mode outputs of up to 90 mW CW, and has maintained a single spatial mode to 150 mW CW. Phase-locked arrays of closely spaced index-guided lasers have been designed and fabricated with the aim of multiplying the outputs of the individual devices to even higher power levels in a stable, single-lobe, anastigmatic beam. The optical modes of the lasers in such arrays can couple together in such a way that they appear to be emanating from a single source, and can therefore be efficiently coupled into optical communications systems. This paper will review the state of high-power laser technology and discuss the communication system implications of these devices.

  6. FPGA-based rate-adaptive LDPC-coded modulation for the next generation of optical communication systems.

    PubMed

    Zou, Ding; Djordjevic, Ivan B

    2016-09-01

    In this paper, we propose a rate-adaptive FEC scheme based on LDPC codes together with its software reconfigurable unified FPGA architecture. By FPGA emulation, we demonstrate that the proposed class of rate-adaptive LDPC codes based on shortening with an overhead from 25% to 42.9% provides a coding gain ranging from 13.08 dB to 14.28 dB at a post-FEC BER of 10-15 for BPSK transmission. In addition, the proposed rate-adaptive LDPC coding combined with higher-order modulations have been demonstrated including QPSK, 8-QAM, 16-QAM, 32-QAM, and 64-QAM, which covers a wide range of signal-to-noise ratios. Furthermore, we apply the unequal error protection by employing different LDPC codes on different bits in 16-QAM and 64-QAM, which results in additional 0.5dB gain compared to conventional LDPC coded modulation with the same code rate of corresponding LDPC code. PMID:27607718

  7. Signal to noise ratio of free space homodyne coherent optical communication after adaptive optics compensation

    NASA Astrophysics Data System (ADS)

    Huang, Jian; Mei, Haiping; Deng, Ke; Kang, Li; Zhu, Wenyue; Yao, Zhoushi

    2015-12-01

    Designing and evaluating the adaptive optics system for coherent optical communication link through atmosphere requires to distinguish the effects of the residual wavefront and disturbed amplitude to the signal to noise ratio. Based on the new definition of coherent efficiency, a formula of signal to noise ratio for describing the performance of coherent optical communication link after wavefront compensation is derived in the form of amplitude non-uniformity and wavefront error separated. A beam quality metric is deduced mathematically to evaluate the effect of disturbed amplitude to the signal to noise ratio. Experimental results show that the amplitude fluctuation on the receiver aperture may reduce the signal to noise ratio about 24% on average when Fried coherent length r0=16 cm.

  8. Optical Communications in the mid-wave IR spectral band

    NASA Astrophysics Data System (ADS)

    Prasad, Narasimha S.

    The mid-wave IR (MWIR) spectral band extending from 3 to 5 microns is considered to be a low loss atmospheric window. The MWIR wavelengths are eye safe and are attractive for several free-space applications including remote sensing of chemical and biological species, hard target imaging, range finding, target illumination, and free-space Communications. Due to the nature of light-matter interaction characteristics, MWIR wavelength based Systems can provide unique advantages over other spectral bands for these applications, The MWIR wavelengths are found to effectively penetrate natural and anthropogenic obscurants. Consequently, MWIR Systems offer increased range Performance at reduced power levels. Free-space, line-of-sight optical communication links for terrestrial as well as space based platforms using MWIR wavelengths can be designed to operate under low visibility conditions. Combined with high-bandwidth, eye-safe, covert and jam proof features, a MWIR wavelength based optical communication link could play a vital role in hostile environments.

  9. Integrated Radio and Optical Communication (iROC)

    NASA Technical Reports Server (NTRS)

    Raible, Daniel; Romanofsky, Robert; Pease, Gary; Kacpura, Thomas

    2016-01-01

    This is an overview of the Integrated Radio and Optical Communication (iROC) Project for Space Communication and Navigation Industry Days. The Goal is to develop and demonstrate new, high payoff space technologies that will promote mission utilization of optical communications, thereby expanding the capabilities of NASA's exploration, science, and discovery missions. This is an overview that combines the paramount features of select deep space RF and optical communications elements into an integrated system, scalable from deep space to near earth. It will realize Ka-band RF and 1550 nanometer optical capability. The approach is to prototype and demonstrate performance of key components to increase to TRL-5, leading to integrated hybrid communications system demonstration to increase to TRL-5, leading to integrated hybrid communications system demonstration.

  10. Optical-fiber laser amplifier for ultrahigh-speed communications

    SciTech Connect

    Gosnell, T.; Xie, Ping; Cockroft, N.

    1996-04-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to develop a praseodymium-based 1.31-{mu}m fiber amplifier that can be optically pumped with off-the-shelf semiconductor diode lasers. Development of optical amplifiers for the 1.31-{mu}m communications window is motivated by the push towards ``all-optical`` networks that will support multigigabits per second communication rates. Our approach exploited radiationless energy transfer from optically pumped Yb{sup 3+} ions co-doped with Pr{sup 3+} into a fluorozirconate glass (ZBLAN). We obtained a gain of approximately 10 on a 1.31-{mu}m amplifier, a value too low for practical applications. In two spin- off applications, all-solid-state operation at all four output wavelengths was achieved in the development of a four-color visible laser, and laser cooling of a solid material was demonstrated for the first time in the development of a fluorescent cryogenic refrigerator.

  11. Optical switches based on semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Kalman, Robert F.; Dias, Antonio R.; Chau, Kelvin K.; Goodman, Joseph W.

    1991-12-01

    Fiber-optic switching systems typically exhibit large losses associated with splitting and combining of the optical power, and with excess component losses. These losses increase quickly with switch size. To obtain acceptable signal-to-noise performance through large optical switching, optical amplifiers can be used. In applications requiring optical switching, semiconductor optical amplifiers (SOAs) are preferred over erbium-doped fiber amplifiers due to their fast switching speeds and the possibility of their integration in monolithic structures with passive waveguides and electronics. We present a general analysis of optical switching systems utilizing SOAs. These systems, in which the gain provided by SOAs is distributed throughout the optical system, are referred to as distributed optical gain (DOG) systems. Our model predicts the performance and achievable sizes of switches based on the matrix-vector multiplier crossbar and Benes network. It is found that for realistic SOA parameters optical switches accommodating extremely large numbers of nodes are, in principle, achievable.

  12. Terahertz wireless communications based on photonics technologies.

    PubMed

    Nagatsuma, Tadao; Horiguchi, Shogo; Minamikata, Yusuke; Yoshimizu, Yasuyuki; Hisatake, Shintaro; Kuwano, Shigeru; Yoshimoto, Naoto; Terada, Jun; Takahashi, Hiroyuki

    2013-10-01

    There has been an increasing interest in the application of terahertz (THz) waves to broadband wireless communications. In particular, use of frequencies above 275 GHz is one of the strong concerns among radio scientists and engineers, because these frequency bands have not yet been allocated at specific active services, and there is a possibility to employ extremely large bandwidths for ultra-broadband wireless communications. Introduction of photonics technologies for signal generation, modulation and detection is effective not only to enhance the bandwidth and/or the data rate, but also to combine fiber-optic (wired) and wireless networks. This paper reviews recent progress in THz wireless communications using telecom-based photonics technologies towards 100 Gbit/s. PMID:24104286

  13. Broadband optical modulators based on graphene supercapacitors.

    PubMed

    Polat, Emre O; Kocabas, Coskun

    2013-01-01

    Optical modulators are commonly used in communication and information technology to control intensity, phase, or polarization of light. Electro-optic, electroabsorption, and acousto-optic modulators based on semiconductors and compound semiconductors have been used to control the intensity of light. Because of gate tunable optical properties, graphene introduces new potentials for optical modulators. The operation wavelength of graphene-based modulators, however, is limited to infrared wavelengths due to inefficient gating schemes. Here, we report a broadband optical modulator based on graphene supercapacitors formed by graphene electrodes and electrolyte medium. The transparent supercapacitor structure allows us to modulate optical transmission over a broad range of wavelengths from 450 nm to 2 μm under ambient conditions. We also provide various device geometries including multilayer graphene electrodes and reflection type device geometries that provide modulation of 35%. The graphene supercapacitor structure together with the high-modulation efficiency can enable various active devices ranging from plasmonics to optoelectronics. PMID:24215484

  14. A Study of Synchronization Techniques for Optical Communication Systems

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.

    1975-01-01

    The study of synchronization techniques and related topics in the design of high data rate, deep space, optical communication systems was reported. Data cover: (1) effects of timing errors in narrow pulsed digital optical systems, (2) accuracy of microwave timing systems operating in low powered optical systems, (3) development of improved tracking systems for the optical channel and determination of their tracking performance, (4) development of usable photodetector mathematical models for application to analysis and performance design in communication receivers, and (5) study application of multi-level block encoding to optical transmission of digital data.

  15. Systems and methods for free space optical communication

    DOEpatents

    Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA

    2011-05-10

    Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.

  16. Measurement-based quantum communication

    NASA Astrophysics Data System (ADS)

    Zwerger, M.; Briegel, H. J.; Dür, W.

    2016-03-01

    We review and discuss the potential of using measurement-based elements in quantum communication schemes, where certain tasks are realized with the help of entangled resource states that are processed by measurements. We consider long-range quantum communication based on the transmission of encoded quantum states, where encoding, decoding and syndrome readout are implemented using small-scale resource states. We also discuss entanglement-based schemes and consider measurement-based quantum repeaters. An important element in these schemes is entanglement purification, which can also be implemented in a measurement-based way. We analyze the influence of noise and imperfections in these schemes and show that measurement-based implementation allows for very large error thresholds of the order of 10 % noise per qubit and more. We show how to obtain optimal resource states for different tasks and discuss first experimental realizations of measurement-based quantum error correction using trapped ions and photons.

  17. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1987-01-01

    A 25 megabit/sec direct detection optical communication system that used Q=4 PPM signalling was constructed and its performance measured under laboratory conditions. The system used a single-mode AlGaAs laser diode transmitter and low noise silicon avalanche photodiode (APD) photodetector. Comparison of measured performance with the theoretical revealed that modeling the APD output as a Gaussian process under conditions of negligible background radiation and low (less than 10 to the -12 power A) APD bulk leakage currents leads to substantial underestimates of optimal APD gain to use and overestimates of system bit error probability. A procedure is given to numerically compute system performance which uses the more accurate Webb's Approximation of the exact Conradi distribution for the APD ouput signal that does not require excessive amounts of computer time (a few minutes of VAX 8600 CPU time per system operating point). Examples are given which illustrate the breakdown of the Gaussian approximation in assessing system performance. This system achieved a bit error probability of 10 to the -6 power at a received signal energy corresponding to an average of 60 absorbed photons/bit and optimal APD gain of 700.

  18. Optical communication with semiconductor laser diodes

    NASA Technical Reports Server (NTRS)

    Davidson, F.

    1988-01-01

    Slot timing recovery in a direct detection optical PPM communication system can be achieved by processing the photodetector waveform with a nonlinear device whose output forms the input to a phase lock group. The choice of a simple transition detector as the nonlinearity is shown to give satisfactory synchronization performance. The rms phase error of the recovered slot clock and the effect of slot timing jitter on the bit error probability were directly measured. The experimental system consisted of an AlGaAs laser diode (lambda = 834 nm) and a silicon avalanche photodiode (APD) photodetector and used Q=4 PPM signaling operated at a source data rate of 25 megabits/second. The mathematical model developed to characterize system performance is shown to be in good agreement with actual performance measurements. The use of the recovered slot clock in the receiver resulted in no degradation in receiver sensitivity compared to a system with perfect slot timing. The system achieved a bit error probability of 10 to the minus 6 power at received signal energies corresponding to an average of less than 60 detected photons per information bit.

  19. Optical space communication II; Proceedings of the Meeting, Munich, Germany, June 10, 11, 1991

    NASA Astrophysics Data System (ADS)

    Franz, Juergen

    1991-05-01

    The present conference discusses the European SILEX project for optical space communications (OSP), Japanese activities in OSPs, deep-space OSP, a high data-rate interorbit link based on diode-pumped Nd:YAG laser technology, an electrooptic modulator for high-speed Nd:YAG laser communications, an unobscured mirror telescope for telecommunications, and optical carrier modulation by integrated optical devices in lithium niobate. Also discussed are micromachined scanning mirrors for laser-beam deflection, coherent optical fiber communications, a 90-deg optical hybrid for coherent receivers, economic factors relevant to an OSP, the effect of microaccelerations on an OSP terminal, and a novel fiber-optics-based conical scan-tracking device.

  20. 77 FR 65713 - Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-30

    ... COMMISSION Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products... the United States after importation of certain optoelectronic devices for fiber optic communications... importation of certain optoelectronic devices for fiber optic communications, components thereof, and...

  1. Multi-wavelength time-coincident optical communications system and methods thereof

    NASA Technical Reports Server (NTRS)

    Lekki, John (Inventor); Nguyen, Quang-Viet (Inventor)

    2009-01-01

    An optical communications transmitter includes a oscillator source, producing a clock signal, a data source, producing a data signal, a modulating circuit for modulating the clock signal using the data signal to produce modulating signals, optical drivers, receiving the modulating signals and producing optical driving signals based on the modulating signals and optical emitters, producing small numbers of photons based on the optical driving signals. The small numbers of photons are time-correlated between at least two separate optical transmission wavelengths and quantum states and the small number of photons can be detected by a receiver to reform the data signal.

  2. Deep-Space Optical Communications: Visions, Trends, and Prospects

    NASA Technical Reports Server (NTRS)

    Cesarone, R. J.; Abraham, D. S.; Shambayati, S.; Rush, J.

    2011-01-01

    Current key initiatives in deep-space optical communications are treated in terms of historical context, contemporary trends, and prospects for the future. An architectural perspective focusing on high-level drivers, systems, and related operations concepts is provided. Detailed subsystem and component topics are not addressed. A brief overview of past ideas and architectural concepts sets the stage for current developments. Current requirements that might drive a transition from radio frequencies to optical communications are examined. These drivers include mission demand for data rates and/or data volumes; spectrum to accommodate such data rates; and desired power, mass, and cost benefits. As is typical, benefits come with associated challenges. For optical communications, these include atmospheric effects, link availability, pointing, and background light. The paper describes how NASA's Space Communication and Navigation Office will respond to the drivers, achieve the benefits, and mitigate the challenges, as documented in its Optical Communications Roadmap. Some nontraditional architectures and operations concepts are advanced in an effort to realize benefits and mitigate challenges as quickly as possible. Radio frequency communications is considered as both a competitor to and a partner with optical communications. The paper concludes with some suggestions for two affordable first steps that can yet evolve into capable architectures that will fulfill the vision inherent in optical communications.

  3. Planets as background noise sources in free space optical communications

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1986-01-01

    Background noise generated by planets is the dominant noise source in most deep space direct detection optical communications systems. Earlier approximate analyses of this problem are based on simplified blackbody calculations and can yield results that may be inaccurate by up to an order of magnitude. Various other factors that need to be taken into consideration, such as the phase angle and the actual spectral dependence of the planet albedo, in order to obtain a more accurate estimate of the noise magnitude are examined.

  4. Research on target information optics communications transmission characteristic and performance in multi-screens testing system

    NASA Astrophysics Data System (ADS)

    Li, Hanshan

    2016-04-01

    To enhance the stability and reliability of multi-screens testing system, this paper studies multi-screens target optical information transmission link properties and performance in long-distance, sets up the discrete multi-tone modulation transmission model based on geometric model of laser multi-screens testing system and visible light information communication principle; analyzes the electro-optic and photoelectric conversion function of sender and receiver in target optical information communication system; researches target information transmission performance and transfer function of the generalized visible-light communication channel; found optical information communication transmission link light intensity space distribution model and distribution function; derives the SNR model of information transmission communication system. Through the calculation and experiment analysis, the results show that the transmission error rate increases with the increment of transmission rate in a certain channel modulation depth; when selecting the appropriate transmission rate, the bit error rate reach 0.01.

  5. A doubly logarithmic communication algorithm for the Completely Connected Optical Communication Parallel Computer

    SciTech Connect

    Goldberg, L.A.; Jerrum, M.; Leighton, T.; Rao, S.

    1993-01-20

    In this paper we consider the problem of interprocessor communication on a Completely Connected Optical Communication Parallel Computer (OCPC). The particular problem we study is that of realizing an h-relation. In this problem, each processor has at most h messages to send and at most h messages to receive. It is clear that any 1-relation can be realized in one communication step on an OCPC. However, the best known p-processor OCPC algorithm for realizing an arbitrary h-relation for h > 1 requires {Theta}(h + log p) expected communication steps. (This algorithm is due to Valiant and is based on earlier work of Anderson and Miller.) Valiant`s algorithm is optimal only for h = {Omega}(log p) and it is an open question of Gereb-Graus and Tsantilas whether there is a faster algorithm for h = o(log p). In this paper we answer this question in the affirmative by presenting a {Theta} (h + log log p) communication step algorithm that realizes an arbitrary h-relation on a p-processor OCPC. We show that if h {le} log p then the failure probability can be made as small as p{sup -{alpha}} for any positive constant {alpha}.

  6. A note on deep space optical communication link parameters

    NASA Technical Reports Server (NTRS)

    Dolinar, S. J.; Yuen, J. H.

    1982-01-01

    Topical communication in the context of a deep space communication link. Communication link analysis at the optical frequencies differs significantly from that at microwave frequencies such as the traditional S and X-bands used in deep space applications, due to the different technology of transmitter, antenna, modulators, and receivers. In addition, the important role of quantum noise in limiting system performance is quite different than that of thermal noise. The optical link design is put in a design control table format similar to a microwave telecom link design. Key considerations unique to the optical link are discussed.

  7. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  8. LEO-to-ground optical communications link using adaptive optics correction on the OPALS downlink

    NASA Astrophysics Data System (ADS)

    Wright, Malcolm W.; Kovalik, Joseph; Morris, Jeff; Abrahamson, Matthew; Biswas, Abhijit

    2016-03-01

    The Optical PAyload for Lasercomm Science (OPALS) experiment on the International Space Station (ISS) recently demonstrated successful optical downlinks to the NASA/JPL 1-m aperture telescope at the Optical Communication Telescope Laboratory (OCTL) located near Wrightwood, CA. A large area (200 μm diameter) free space coupled avalanche photodiode (APD) detector was used to receive video and a bit patterns at 50 Mb/s. We report on a recent experiment that used an adaptive optics system at OCTL to correct for atmospherically-induced refractive index fluctuations so that the downlink from the ISS could be coupled into a single mode fiber receiver. Stable fiber coupled power was achieved over an entire pass using a self-referencing interferometer based adaptive optics system that was provided and operated by Boeing Co. and integrated to OCTL. End-to-end transmission and reconstruction of an HD video signal verified the communication performance as in the original OPALS demonstration. Coupling the signal into a single mode fiber opens the possibility for higher bandwidth and efficiency modulation schemes and serves as a pilot experiment for future implementations.

  9. Advanced Optical Technologies in NASA's Space Communication Program: Status, Challenges, and Future Plans

    NASA Technical Reports Server (NTRS)

    Pouch, John

    2004-01-01

    A goal of the NASA Space Communications Project is to enable broad coverage for high-data-rate delivery to the users by means of ground, air, and space-based assets. The NASA Enterprise need will be reviewed. A number of optical space communications technologies being developed by NASA will be described, and the prospective applications will be discussed.

  10. Soliton communication lines based on spectrally efficient modulation formats

    SciTech Connect

    Yushko, O V; Redyuk, A A

    2014-06-30

    We report the results of mathematical modelling of optical-signal propagation in soliton fibre-optic communication lines (FOCLs) based on spectrally efficient signal modulation formats. We have studied the influence of spontaneous emission noise, nonlinear distortions and FOCL length on the data transmission quality. We have compared the characteristics of a received optical signal for soliton and conventional dispersion compensating FOCLs. It is shown that in the presence of strong nonlinearity long-haul soliton FOCLs provide a higher data transmission performance, as well as allow higher order modulation formats to be used as compared to conventional communication lines. In the context of a coherent data transmission, soliton FOCLs allow the use of phase modulation with many levels, thereby increasing the spectral efficiency of the communication line. (optical communication lines)

  11. Atmospheric channel for bistatic optical communication: simulation algorithms

    NASA Astrophysics Data System (ADS)

    Belov, V. V.; Tarasenkov, M. V.

    2015-11-01

    Three algorithms of statistical simulation of the impulse response (IR) for the atmospheric optical communication channel are considered, including algorithms of local estimate and double local estimate and the algorithm suggested by us. On the example of a homogeneous molecular atmosphere it is demonstrated that algorithms of double local estimate and the suggested algorithm are more efficient than the algorithm of local estimate. For small optical path length, the proposed algorithm is more efficient, and for large optical path length, the algorithm of double local estimate is more efficient. Using the proposed algorithm, the communication quality is estimated for a particular case of the atmospheric channel under conditions of intermediate turbidity. The communication quality is characterized by the maximum IR, time of maximum IR, integral IR, and bandwidth of the communication channel. Calculations of these criteria demonstrated that communication is most efficient when the point of intersection of the directions toward the source and the receiver is most close to the source point.

  12. Heterodyne and coherent optical fiber communications - Recent progress

    NASA Astrophysics Data System (ADS)

    Okoshi, T.

    1982-08-01

    It is pointed out that the present optical fiber communications are in a sense as primitive as the radio communications prior to 1930. The modulation/demodulation scheme being employed in the present standard optical fiber communications is often called the intensity-modulation/direct-detection (IM/DD) scheme. According to this scheme, no attention is paid to the phase of the carrier. On the other hand, in the history of radio communications, the heterodyne scheme became common since 1930, and coherent modulations such as FM, PM, FSK, and PSK are currently widely used. The question arises whether a similar development might occur in optical communications. The IM/DD system has a great advantage in system simplicity and low cost. However, for certain applications a heterodyne/coherent system would provide distinct improvements. An investigation indicates that, despite technical difficulties, and heterodyne/coherent system is a promising and interesting technical target.

  13. Networked Operations of Hybrid Radio Optical Communications Satellites

    NASA Technical Reports Server (NTRS)

    Hylton, Alan; Raible, Daniel

    2014-01-01

    In order to address the increasing communications needs of modern equipment in space, and to address the increasing number of objects in space, NASA is demonstrating the potential capability of optical communications for both deep space and near-Earth applications. The Integrated Radio Optical Communications (iROC) is a hybrid communications system that capitalizes on the best of both the optical and RF domains while using each technology to compensate for the other's shortcomings. Specifically, the data rates of the optical links can be higher than their RF counterparts, whereas the RF links have greater link availability. The focus of this paper is twofold: to consider the operations of one or more iROC nodes from a networking point of view, and to suggest specific areas of research to further the field. We consider the utility of Disruption Tolerant Networking (DTN) and the Virtual Mission Operation Center (VMOC) model.

  14. Periodic nonlinear Fourier transform for fiber-optic communications, Part II: eigenvalue communication.

    PubMed

    Kamalian, Morteza; Prilepsky, Jaroslaw E; Le, Son Thai; Turitsyn, Sergei K

    2016-08-01

    In this paper we propose the design of communication systems based on using periodic nonlinear Fourier transform (PNFT), following the introduction of the method in the Part I. We show that the famous "eigenvalue communication" idea [A. Hasegawa and T. Nyu, J. Lightwave Technol. 11, 395 (1993)] can also be generalized for the PNFT application: In this case, the main spectrum attributed to the PNFT signal decomposition remains constant with the propagation down the optical fiber link. Therefore, the main PNFT spectrum can be encoded with data in the same way as soliton eigenvalues in the original proposal. The results are presented in terms of the bit-error rate (BER) values for different modulation techniques and different constellation sizes vs. the propagation distance, showing a good potential of the technique. PMID:27505800

  15. Fiber-Optic Links Carry Two Communication Channels Apiece

    NASA Technical Reports Server (NTRS)

    Huang, Po T.; Hand, Larry J., Jr.; Stute, Robert A.; Galloway, F. Houston; Swindle, Robert W.

    1996-01-01

    System of multimode fiber-optic communication links upgraded to enable simultaneous communication on two channels in each fiber. Incorporates two-wavelength-division multiplexing at both ends of each fiber so two signals transmitted, either in same direction or in opposite directions.

  16. Quantum issues in optical communication. [noise reduction in signal reception

    NASA Technical Reports Server (NTRS)

    Kennedy, R. S.

    1973-01-01

    Various approaches to the problem of controlling quantum noise, the dominant noise in an optical communications system, are discussed. It is shown that, no matter which way the problem is approached, there always remain uncertainties. These uncertainties exist because, to date, only very few communication problems have been solved in their full quantum form.

  17. 4.8 Gbit/s 16-QAM-OFDM transmission based on compact 450-nm laser for underwater wireless optical communication.

    PubMed

    Oubei, Hassan M; Duran, Jose R; Janjua, Bilal; Wang, Huai-Yung; Tsai, Cheng-Ting; Chi, Yu-Cheih; Ng, Tien Khee; Kuo, Hao-Chung; He, Jr-Hau; Alouini, Mohamed-Slim; Lin, Gong-Ru; Ooi, Boon S

    2015-09-01

    We experimentally demonstrate an underwater wireless optical communications (UWOC) employing 450-nm TO-9 packaged and fiber-pigtailed laser diode (LD) directly encoded with an orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) data. A record data rate of up to 4.8 Gbit/s over 5.4-m transmission distance is achieved. By encoding the full 1.2-GHz bandwidth of the 450-nm LD with a 16-QAM-OFDM data, an error vector magnitude (EVM) of 16.5%, a signal-to-noise ratio (SNR) of 15.63 dB and a bit error rate (BER) of 2.6 × 10(-3), well pass the forward error correction (FEC) criterion, were obtained. PMID:26368431

  18. In-service communication channel sensing based on reflectometry for dynamic wavelength assigned wavelength- and time-division multiplexed passive optical network systems

    NASA Astrophysics Data System (ADS)

    Iida, Daisuke; Kuwano, Shigeru; Terada, Jun

    2015-04-01

    In future radio access systems, base stations will be mainly accommodated in wavelength- and time-division multiplexing passive optical network (PON) based mobile backhaul and fronthaul networks, and in such networks, failed connections in an optical network unit (ONU) wavelength channel will severely degrade mobile system performance. A cost-effective in-service ONU wavelength channel monitor is essential to ensure proper system operation without failed connections. To address this issue, we propose a reflectometry-based remote sensing method that provides ONU wavelength channel information with the optical line terminal-ONU distance. The proposed method enables real-time monitoring of ONU wavelength channels without data signal quality degradation and is also able to determine if the ONUs are connected to the PON. Experimental results show that it achieves wavelength channel distinction with a high distance resolution (˜10 m). Additionally, with the method, the distance resolution for distinguishing the ONUs after the PON splitter is determined by the received signal bandwidth or the test light modulation speed rather than by the pulse width as in conventional optical time-domain reflectometry.

  19. A visibility characterization program for optical communications through the atmosphere

    NASA Technical Reports Server (NTRS)

    Cowles, K.

    1989-01-01

    A program is described for characterizing the atmosphere as it affects optical communications from a spacecraft. Cloud cover patterns and optical transmission will be determined by setting up three automated observatories in the Southwestern United States. Methods of site selection and operation of hardware and software components are presented, as well as plans for term deployment.

  20. Fiber-Optic Communication Technology Branching Devices

    NASA Astrophysics Data System (ADS)

    Williams, J. C.

    1985-02-01

    This tutorial review of fiber-optic branching devices covers example uses of branching devices, device types, device-performance characteristics, examples of current technology, and system-design methodology. The discussion is limited to passive single- and multimode devices fabricated from optical fibers or graded-index components. Integrated-optic, wavelength-division-multiplexing, and polarization-selective devices are not specifically addressed.

  1. Fiber-Optic Terahertz Data-Communication Networks

    NASA Technical Reports Server (NTRS)

    Chua, Peter L.; Lambert, James L.; Morookian, John M.; Bergman, Larry A.

    1994-01-01

    Network protocols implemented in optical domain. Fiber-optic data-communication networks utilize fully available bandwidth of single-mode optical fibers. Two key features of method: use of subpicosecond laser pulses as carrier signals and spectral phase modulation of pulses for optical implementation of code-division multiple access as multiplexing network protocol. Local-area network designed according to concept offers full crossbar functionality, security of data in transit through network, and capacity about 100 times that of typical fiber-optic local-area network in current use.

  2. Fiber optic communication technology; Proceedings of the Meeting, San Diego, CA, August 23, 24, 1984

    NASA Astrophysics Data System (ADS)

    Kleekamp, C. W.

    Fiber optic components are considered, taking into account a review of developments related to optical fibers, a review of fiber optic cable technology, aspects of fiber system testing, fiber optic splices, a critical review of fiber optic connectors, and fiber optic communication technology branching devices. Developments concerning fiber optic systems are also discussed, giving attention to optoelectronic issues in fiber optic communications, digital fiber optic systems, wideband analog fiber optic systems, fiber optic local area networks, and wavelength division multiplexing.

  3. Optimization of spatial acquisition systems for low-light-level robustness in space optical communications.

    PubMed

    Bai, Shuai; Qiang, Jia; Zhang, Liang; Wang, Jianyu

    2015-08-15

    The channel establishment in space optical communications relies on the Acquisition, Tracking, and Pointing (ATP) systems to initially acquire and then stably track the beacon beam. However, insufficient optical power may lead to unstable acquisition or even acquisition failure. In this Letter, we describe the mechanisms causing the instability, and then propose an approach to constrain the acquisition velocity. The approach is based on velocity prediction obtained from the light spot centroids and angle measurement data. Theoretical and experimental results show that the acceptable minimum optical power for acquisition decreases by 5.5 dB after optimization, which effectively enhances the acquisition system's robustness under low-light-level conditions. This approach improves the adaptability of satellite-ground optical communications and also has practical value for deep-space optical communications. PMID:26274651

  4. Channel-capacity gain in entanglement-assisted communication protocols based exclusively on linear optics, single-photon inputs, and coincidence photon counting

    DOE PAGESBeta

    Lougovski, P.; Uskov, D. B.

    2015-08-04

    Entanglement can effectively increase communication channel capacity as evidenced by dense coding that predicts a capacity gain of 1 bit when compared to entanglement-free protocols. However, dense coding relies on Bell states and when implemented using photons the capacity gain is bounded by 0.585 bits due to one's inability to discriminate between the four optically encoded Bell states. In this research we study the following question: Are there alternative entanglement-assisted protocols that rely only on linear optics, coincidence photon counting, and separable single-photon input states and at the same time provide a greater capacity gain than 0.585 bits? In thismore » study, we show that besides the Bell states there is a class of bipartite four-mode two-photon entangled states that facilitate an increase in channel capacity. We also discuss how the proposed scheme can be generalized to the case of two-photon N-mode entangled states for N=6,8.« less

  5. Channel-capacity gain in entanglement-assisted communication protocols based exclusively on linear optics, single-photon inputs, and coincidence photon counting

    SciTech Connect

    Lougovski, P.; Uskov, D. B.

    2015-08-04

    Entanglement can effectively increase communication channel capacity as evidenced by dense coding that predicts a capacity gain of 1 bit when compared to entanglement-free protocols. However, dense coding relies on Bell states and when implemented using photons the capacity gain is bounded by 0.585 bits due to one's inability to discriminate between the four optically encoded Bell states. In this research we study the following question: Are there alternative entanglement-assisted protocols that rely only on linear optics, coincidence photon counting, and separable single-photon input states and at the same time provide a greater capacity gain than 0.585 bits? In this study, we show that besides the Bell states there is a class of bipartite four-mode two-photon entangled states that facilitate an increase in channel capacity. We also discuss how the proposed scheme can be generalized to the case of two-photon N-mode entangled states for N=6,8.

  6. Redundant uplink optical channel for visible light communication systems

    NASA Astrophysics Data System (ADS)

    Vladescu, Marian; Vuza, Dan Tudor

    2015-02-01

    The increased interest in optical wireless (OW), as a complementary solution for radio frequency (RF) wireless technology, in conjunction with the significant deployments in LED lighting technology, led to the need to achieve lighting and wireless communication simultaneously in indoor environments. Visible light communication (VLC) technology provides an opportunity and infrastructure for the high-speed low-cost wireless communication. There are still open issues in VLC such as: uplink channel, LED modulation bandwidth, and LED nonlinearity. In this paper we addressed the uplink channel implementation, being a key issue in the OW communication system in order to allow full connectivity for a terminal (duplex transmission). VLC in full duplex mode requires the usage of a hybrid technology, such as infrared optical uplink, retro-reflecting transceivers, or even RF. The solution we proposed is to create a redundant optical uplink channel, using near ultraviolet (UV) and near infrared (IR) spectra.

  7. Physics Behind Optical Fiber Communications: Technologies that Drive the Internet Capacity Growth

    NASA Astrophysics Data System (ADS)

    Willner, Alan

    Optical fiber communications forms the backbone for global communications, especially as it relates to the Internet. Indeed, the Internet as we know it today would not exist without optical communications. The data transmission capacity through an optical fiber has undergone an exponential growth increase for decades, progressing from Megabits/sec to now Petabits/sec in just the past 40 years. This growth came about due to many physics advances in the field of optical fiber communications, dating back to 1966 when Sir Charles Kao proposed the idea of a communication system based on low-loss optical glass fiber. This presentation will explore the past and present physics-based crucial innovations needed for this continuing story. Specific topics to be highlighted include: (a) ultra-pure fiber that decreased the attenuation losses through glass by many orders of magnitude, (b) single-frequency lasers that defined a specific data channel that could propagate with low signal distortion, (c) Erbium-doped fiber amplifiers that had high gain and low additive noise allowing for amplifier cascades and conquering enormous distances, (d) the simultaneous transmission of multiple wavelength-division-multiplexing data channels down the optical fiber, and (e) the tackling of various dispersive and nonlinear effects that are introduced by the optical fiber itself, cause the data to degrade, and necessitate some form of compensation or management.

  8. Optical MEMS-based arrays

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.

    2003-07-01

    Industrial Micro Electro Mechanical Systems (MEMS) developers are rapidly bringing to demonstration inertial radio frequency, and optical MEMS devices and components. The Army has a requirement for compact, highly reliable, and inexpensive laser beam steering components for missile seekers and unmanned aerial vehicles remote sensing components to provide a fast scanning capability for pointing, acquisition, tracking, and data communication. The coupling of this requirement with recent developments in the micro-optics area, has led scientists and engineers at the Army Aviation and Missile Command (AMCOM) to consider optical MEMS-based phased arrays, which have potential applications in the commercial industry as well as in the military, as a replacement for gimbals. Laser beam steering in commercial applications such as free space communicataion, scanning display, bar-code reading, and gimbaled seekers; require relatively large monolithic micro-mirrors to accomplish the required optical resolution. The Army will benefit from phased arrays composed of relatively small micro-mirrors that can be actuated through large deflection angles with substantially reduced volume times. The AMCOM Aviation and Missile Research, Development, and Engineering Center (AMRDEC) has initiated a research project to develop MEMS-based phased arrays for use in a small volume, inexpensive Laser Detection and Ranging (LADAR) seeker that is particularly attractive because of its ability to provide large field-of-regard and autonomous target acquisition for reconnaissance mission applications. The primary objective of the collaborative project with the Defence Advanced Research Projects Agency (DARPA) is to develop a rugged, MEMS-based phased arrays for incorporation into the 2-D scanner of a LADAR seeker. Design challenges and approach to achieving performance requirements will be discussed.

  9. Pointing Reference Scheme for Free-Space Optical Communications Systems

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm; Ortiz, Gerardo; Jeganathan, Muthu

    2006-01-01

    A scheme is proposed for referencing the propagation direction of the transmit laser signal in pointing a free-space optical communications terminal. This recently developed scheme enables the use of low-cost, commercial silicon-based sensors for tracking the direction of the transmit laser, regardless of the transmit wavelength. Compared with previous methods, the scheme offers some advantages of less mechanical and optical complexity and avoids expensive and exotic sensor technologies. In free-space optical communications, the transmit beam must be accurately pointed toward the receiver in order to maintain the communication link. The current approaches to achieve this function call for part of the transmit beam to be split off and projected onto an optical sensor used to infer the pointed direction. This requires that the optical sensor be sensitive to the wavelength of the transmit laser. If a different transmit wavelength is desired, for example to obtain a source capable of higher data rates, this can become quite impractical because of the unavailability or inefficiency of sensors at these wavelengths. The innovation proposed here decouples this requirement by allowing any transmit wavelength to be used with any sensor. We have applied this idea to a particular system that transmits at the standard telecommunication wavelength of 1,550 nm and uses a silicon-based sensor, sensitive from 0.5 to 1.0 micrometers, to determine the pointing direction. The scheme shown in the figure involves integrating a low-power 980-nm reference or boresight laser beam coupled to the 1,550-nm transmit beam via a wavelength-division-multiplexed fiber coupler. Both of these signals propagate through the optical fiber where they achieve an extremely high level of co-alignment before they are launched into the telescope. The telescope uses a dichroic beam splitter to reflect the 980- nm beam onto the silicon image sensor (a quad detector, charge-coupled device, or active

  10. Experimental demonstration of low-complexity fiber chromatic dispersion mitigation for reduced guard-interval OFDM coherent optical communication systems based on digital spectrum sub-band multiplexing.

    PubMed

    Malekiha, Mahdi; Tselniker, Igor; Nazarathy, Moshe; Tolmachev, Alex; Plant, David V

    2015-10-01

    We experimentally demonstrate a novel digital signal processing (DSP) structure for reduced guard-interval (RGI) OFDM coherent optical systems. The proposed concept is based on digitally slicing optical channel bandwidth into multiple spectrally disjoint sub-bands which are then processed in parallel. Each low bandwidth sub-band has a smaller delay-spread compared to a full-band signal. This enables compensation of both chromatic dispersion (CD) and polarization mode dispersion using a simple timing and one-tap-per-symbol frequency domain equalizer with a small cyclic prefix overhead. In terms of the DSP architecture, this allows for a highly efficient parallelization of DSP tasks performed over the received signal samples by deploying multiple processors running at a lower clock rate. It should be noted that this parallelization is performed in the frequency domain and it allows for flexible optical transceiver schemes. In addition, the resulting optical receiver is simplified due to the removal of the CD compensation equalizer compared to conventional RGI-OFDM systems. In this paper we experimentally demonstrate digital sub-banding of optical bandwidth. We test the system performance for different modulation formats (QPSK, 16QAM and 32QAM) over various transmission distances and optical launch powers using a 1.5% CP overhead in all scenarios. We also compare the proposed RGI-OFDM architecture performance against common single carrier modulation formats. At the same total data rate and signal bandwidth both systems have similar performance and transmission reach whereas the proposed method allows for a significant reduction of computational complexity due to removal of CD pre/post compensation equalizer. PMID:26480077

  11. Horizontal Path Laser Communications Employing MEMS Adaptive Optics Correction

    SciTech Connect

    Thompson, C A; Wilks, S C; Brase, J M; Young, R A; Johnson, G W; Ruggiero, A J

    2001-09-05

    Horizontal path laser communications are beginning to provide attractive alternatives for high-speed optical communications, In particular, companies are beginning to sell fiberless alternatives for intranet and sporting event video. These applications are primarily aimed at short distance applications (on the order of 1 km pathlength). There exists a potential need to extend this pathlength to distances much greater than a 1km. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational components. In this paper we detail two Adaptive Optics approaches for improved through-put, the first is the compensated receiver (the traditional Adaptive Optics approach), the second is the compensated transmitter/receiver. The second approach allows for correction of the optical wavefront before transmission from the transmitter and prior to detection at the receiver.

  12. Optical deep space communication via relay satellite

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.; Vilnrotter, V. A.; Dolinar, S. J., Jr.

    1981-01-01

    The possible use of an optical for high rate data transmission from a deep space vehicle to an Earth-orbiting relay satellite while RF links are envisioned for the relay to Earth link was studied. A preliminary link analysis is presented for initial sizing of optical components and power levels, in terms of achievable data rates and feasible range distances. Modulation formats are restricted to pulsed laser operation, involving bot coded and uncoded schemes. The advantage of an optical link over present RF deep space link capabilities is shown. The problems of acquisition, pointing and tracking with narrow optical beams are presented and discussed. Mathematical models of beam trackers are derived, aiding in the design of such systems for minimizing beam pointing errors. The expected orbital geometry between spacecraft and relay satellite, and its impact on beam pointing dynamics are discussed.

  13. Wavelength division multiplexing. [in fiber optics communication systems

    NASA Technical Reports Server (NTRS)

    Hendricks, H. D.

    1985-01-01

    Wavelength division multiplexing (WDM) represents an approach for expanding the communication capacity and for implementing special data techniques in a fiber optics system. This technology is implemented by adding optical sources of different wavelengths at optical transmitting locations. The present paper is concerned with some of the current efforts in WDM. WDM applications are related to long haul communications, local area data networks, spacecraft and aircraft data systems, fault tolerant computer networks, special sensor devices, high speed data processors, closed circuit and cable television, and submarine cable systems. Attention is given to the current state of wavelength division multiplexing applications, the availability and status of WDM components semiconductor lasers/transmitters, availability and status of fiber optic detectors/receivers, optical fibers/cables/connectors/taps/star couplers, wavelength multiplexers/demultiplexers, and future WDM for local area networks.

  14. Optical Communications Study for the Next Generation Space Telescope

    NASA Technical Reports Server (NTRS)

    Ceniceros, Juan M.

    2000-01-01

    The Next Generation Space Telescope (NGST), part of NASA's Origins program, is a follow on to the Hubble Space Telescope expected to provide timely new science along with answering fundamental questions. NGST is a large diameter, infrared optimized telescope with imaging and spectrographic detectors which will be used to help study the origin of galaxies. Due to the large data NGST will collect, Goddard Space Flight Center has considered the use of optical communications for data downlink. The Optical Communications Group at the Jet Propulsion Laboratory has performed a study on optical communications systems for NGST. The objective of the study was to evaluate the benefits gained through the use of optical communication technologies. Studies were performed for each of four proposed NGST orbits. The orbits considered were an elliptical orbit about the semi stable second Lagrangian point, a 1 by 3 AU elliptic orbit around the sun, a 1 AU drift orbit, and a 1 AU drift orbit at a 15 degree incline to the ecliptic plane. An appropriate optical communications system was determined for each orbit. Systems were evaluated in terms of mass, power consumption, size, and cost for each of the four proposed orbits.

  15. Optical performance monitoring for the next generation optical communication networks

    NASA Astrophysics Data System (ADS)

    Pan, Zhongqi; Yu, Changyuan; Willner, Alan E.

    2010-01-01

    Today's optical networks function are in a fairly static fashion and are built to operate within well-defined specifications. This scenario is quite challenging for next generation high-capacity systems, since network paths are not static and channel-degrading effects can change with temperature, component drift, aging, fiber plant maintenance and many other factors. Moreover, we are far from being able to simply "plug-and-play" an optical node into an existing network in such a way that the network itself can allocate resources to ensure error-free transmission. Optical performance monitoring could potentially enable higher stability, reconfigurability, and flexibility in a self-managed optical network. This paper will describe the specific fiber impairments that future intelligent optical network might want to monitor as well as some promising techniques.

  16. Scrambled coherent superposition for enhanced optical fiber communication in the nonlinear transmission regime.

    PubMed

    Liu, Xiang; Chandrasekhar, S; Winzer, P J; Chraplyvy, A R; Tkach, R W; Zhu, B; Taunay, T F; Fishteyn, M; DiGiovanni, D J

    2012-08-13

    Coherent superposition of light waves has long been used in various fields of science, and recent advances in digital coherent detection and space-division multiplexing have enabled the coherent superposition of information-carrying optical signals to achieve better communication fidelity on amplified-spontaneous-noise limited communication links. However, fiber nonlinearity introduces highly correlated distortions on identical signals and diminishes the benefit of coherent superposition in nonlinear transmission regime. Here we experimentally demonstrate that through coordinated scrambling of signal constellations at the transmitter, together with appropriate unscrambling at the receiver, the full benefit of coherent superposition is retained in the nonlinear transmission regime of a space-diversity fiber link based on an innovatively engineered multi-core fiber. This scrambled coherent superposition may provide the flexibility of trading communication capacity for performance in future optical fiber networks, and may open new possibilities in high-performance and secure optical communications. PMID:23038549

  17. Optical performance monitoring in high-speed optical fiber communication systems

    NASA Astrophysics Data System (ADS)

    Yu, Changyuan; Yang, Jing; Hu, Junhao; Zhang, Banghong

    2011-11-01

    Optical performance monitoring (OPM) becomes an attractive topic as the rapid growth of data rate in optical communication networks. It provides improved operation of the high capacity optical transmission systems. Among the various impairments, chromatic dispersion (CD) is one of major factors limiting the transmission distance in high-speed communication systems. Polarization-mode dispersion (PMD) also becomes a degrading effect in the system with data rate larger than 40 Gbit/s. In this paper, we summarize several CD and PMD monitoring methods based on RF spectrum analysis and delay-tap sampling. By using a narrow band fiber Bragg grating (FBG) notch filter, centered at 10 GHz away from the optical carrier, 10-GHz RF power can be used as a CD-insensitive PMD monitoring signal. By taking the 10-GHz RF power ratio of non-filtered and filtered signal, PMD-insensitive CD monitoring can be achieved. If the FBG notch filter is placed at optical carrier, the RF clock power ratio between non-filtered and filtered signal is also a PMDinsensitive CD monitoring parameter, which has larger RF power dynamic range and better measurement resolution. Both simulation and experiment results show that the proposed methods are efficient on measuring CD and PMD values in 57-Gbit/s D8PSK systems. Delay-tap sampling is another efficient method of measuring residual CD. Amplitude ratio of asynchronous delay-tap sampling plot decreases with CD monotonously, and the amplitude ratio can be obtained by using low bandwidth balanced receiver. The simulated results show that our method is efficient on residual CD measurement in 50-Gbit/s 50% RZ DQPSK systems with a 12-GHz balanced receiver. Since no modification on the transmitter or receiver is required, the proposed scheme is simple and cost effective.

  18. Per-Pixel, Dual-Counter Scheme for Optical Communications

    NASA Technical Reports Server (NTRS)

    Farr, William H.; Bimbaum, Kevin M.; Quirk, Kevin J.; Sburlan, Suzana; Sahasrabudhe, Adit

    2013-01-01

    Free space optical communications links from deep space are projected to fulfill future NASA communication requirements for 2020 and beyond. Accurate laser-beam pointing is required to achieve high data rates at low power levels.This innovation is a per-pixel processing scheme using a pair of three-state digital counters to implement acquisition and tracking of a dim laser beacon transmitted from Earth for pointing control of an interplanetary optical communications system using a focal plane array of single sensitive detectors. It shows how to implement dim beacon acquisition and tracking for an interplanetary optical transceiver with a method that is suitable for both achieving theoretical performance, as well as supporting additional functions of high data rate forward links and precision spacecraft ranging.

  19. Exabit optical communication explored using 3M scheme

    NASA Astrophysics Data System (ADS)

    Nakazawa, Masataka

    2014-08-01

    The capacity of the optical communication infrastructure in backbone networks has increased 1000-fold over the last 20 years. Despite this rapid progress, internet traffic is continuing to grow at an annual rate of 40%. This means that in 20 years, we will need petabit/s or even exabit/s optical communication. In this paper, we present recent challenges and efforts toward achieving a hardware paradigm shift to overcome the capacity limitation imposed by the current optical communication infrastructure. We will overview the latest advances on the three “multi” technologies, i.e., multi-level transmission with ultrahigh spectral efficiency, space division multiplexing in multi-core fibers, and mode division multiplexing with multiple-input multiple-output (MIMO).

  20. Quantum communication with coherent states and linear optics

    NASA Astrophysics Data System (ADS)

    Arrazola, Juan Miguel; Lütkenhaus, Norbert

    2014-10-01

    We introduce a general mapping for encoding quantum communication protocols involving pure states of multiple qubits, unitary transformations, and projective measurements into another set of protocols that employ a coherent state of light in a linear combination of optical modes, linear-optics transformations, and measurements with single-photon threshold detectors. This provides a general framework for transforming protocols in quantum communication into a form in which they can be implemented with current technology. We explore the similarity between properties of the original qubit protocols and the coherent-state protocols obtained from the mapping and make use of the mapping to construct additional protocols in the context of quantum communication complexity and quantum digital signatures. Our results have the potential of bringing a wide class of quantum communication protocols closer to their experimental demonstration.

  1. Apparatus for Teaching Physics: Optical Fiber Communications.

    ERIC Educational Resources Information Center

    Throckmorton, Carl; Dey, Joe

    1988-01-01

    Describes a demonstration of the transmission of data signals from one microcomputer to another using an optical fiber line. Discusses the set-up method and demonstration steps for sending program and graphics. Provides a block diagram of the system and two circuit diagrams. (YP)

  2. Estimation and tracking for deep-space optical communications

    NASA Technical Reports Server (NTRS)

    Win, Moe Zaw

    1989-01-01

    The importance of pointing and tracking is demonstrated with current deep-space optical communications system concepts. Maximum-likelihood (ML), minimum square counting-error (MSCE), and maximum product (MP) estimation algorithms (or decision rules) are derived to estimate the location of the receiving station to subpixel resolution. Comparisons of the above algorithms are made, via Monte Carlo computer simulation, in terms of estimator's bias and variance. Optical communication link analyses are made for a typical earth-Mars scenario, to gain engineering insights. It is observed that both the ML rule and the MSCE rule perform better than the MP rule.

  3. Optimization of level spacing in quaternary optical communication systems

    NASA Astrophysics Data System (ADS)

    Rebola, Joao L.; Cartaxo, Adolfo V. T.

    2000-12-01

    In this work, the optimization of level spacing in terms of the extinction ratio variation in quaternary optical communication systems is investigated, for signal-dependent noise dominance. It is shown that the performance of optically preamplified quaternary communication systems can be optimized in terms of levels spacing using very simple formulas, also derived in this work. For the null extinction ratio, sensitivity improvements of about 6 dB can be achieved by proper location of signal levels in comparison with the sensitivity of equally spaced levels. At high extinction ratio, this improvement is not so significant.

  4. LACOMA- OPTICAL ANALYSIS FOR LASER HETERODYNE COMMUNICATION SYSTEM

    NASA Technical Reports Server (NTRS)

    Cohen, S.

    1994-01-01

    LACOMA (Laser Communicator Analysis Program) was developed to predict the effects of optical aberrations on transmitters and receivers used in heterodyne communication systems. Combining the proven techniques of a previous optical program with a new approach designed to evaluate heterodyne performance, the program is a general purpose package to be used by optical and communication engineers. Two independent optical trains for the received signal and the local oscillator are specified and evaluated. A comprehensive ray trace subroutine and Fourier transform compute complex amplitude spread functions in a specified detector plane. The two functions are combined and integrated over a specific detector to determine heterodyne signal power. This power is normalized with respect to an ideal value to provide a quantitative value for receiver degradation. Values of local oscillator illumination efficiency, optical transmission, detection efficiency and phase match efficiency are also evaluated to isolate the cause of any unexpected degradations. The program has been used for a tolerance analysis of a selected system designed for space communications, and for evaluation of several other systems. This program was implemented on an IBM 360/91 and an IBM 360/95 and needs approximately 103K bytes of core.

  5. Beam width and transmitter power adaptive to tracking system performance for free-space optical communication.

    PubMed

    Arnon, S; Rotman, S; Kopeika, N S

    1997-08-20

    The basic free-space optical communication system includes at least two satellites. To communicate between them, the transmitter satellite must track the beacon of the receiver satellite and point the information optical beam in its direction. Optical tracking and pointing systems for free space suffer during tracking from high-amplitude vibration because of background radiation from interstellar objects such as the Sun, Moon, Earth, and stars in the tracking field of view or the mechanical impact from satellite internal and external sources. The vibrations of beam pointing increase the bit error rate and jam communication between the two satellites. One way to overcome this problem is to increase the satellite receiver beacon power. However, this solution requires increased power consumption and weight, both of which are disadvantageous in satellite development. Considering these facts, we derive a mathematical model of a communication system that adapts optimally the transmitter beam width and the transmitted power to the tracking system performance. Based on this model, we investigate the performance of a communication system with discrete element optical phased array transmitter telescope gain. An example for a practical communication system between a Low Earth Orbit Satellite and a Geostationary Earth Orbit Satellite is presented. From the results of this research it can be seen that a four-element adaptive transmitter telescope is sufficient to compensate for vibration amplitude doubling. The benefits of the proposed model are less required transmitter power and improved communication system performance. PMID:18259455

  6. Method and apparatus for optical communication by frequency modulation

    DOEpatents

    Priatko, Gordon J.

    1988-01-01

    Laser optical communication according to this invention is carried out by producing multi-frequency laser beams having different frequencies, splitting one or more of these constituent beams into reference and signal beams, encoding information on the signal beams by frequency modulation and detecting the encoded information by heterodyne techniques. Much more information can be transmitted over optical paths according to the present invention than with the use of only one path as done previously.

  7. Reciprocity-enhanced optical communication through atmospheric turbulence - part II: communication architectures and performance

    NASA Astrophysics Data System (ADS)

    Puryear, Andrew L.; Shapiro, Jeffrey H.; Parenti, Ronald R.

    2012-10-01

    Free-space optical communication provides rapidly deployable, dynamic communication links that are capable of very high data rates compared with those of radio-frequency systems. As such, free-space optical communication is ideal for mobile platforms, for platforms that require the additional security afforded by the narrow divergence of a laser beam, and for systems that must be deployed in a relatively short time frame. In clear-weather conditions the data rate and utility of free-space optical communication links are primarily limited by fading caused by micro-scale atmospheric temperature variations that create parts-per-million refractive-index fluctuations known as atmospheric turbulence. Typical communication techniques to overcome turbulence-induced fading, such as interleavers with sophisticated codes, lose viability as the data rate is driven higher or the delay requirement is driven lower. This paper, along with its companion [J. H. Shapiro and A. Puryear, "Reciprocity-Enhanced Optical Communication through Atmospheric Turbulence-Part I: Reciprocity Proofs and Far-Field Power Transfer"], present communication systems and techniques that exploit atmospheric reciprocity to overcome turbulence which are viable for high data rate and low delay requirement systems. Part I proves that reciprocity is exhibited under rather general conditions, and derives the optimal power-transfer phase compensation for far-field operation. The Part II paper presents capacity-achieving architectures that exploit reciprocity to overcome the complexity and delay issues that limit state-of-the art free-space optical communications. Further, this paper uses theoretical turbulence models to determine the performance—delay, throughput, and complexity—of the proposed architectures.

  8. Blocking Losses on an Optical Communications Link

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Piazzolla, Sabino

    2011-01-01

    Many photon-counting photo-detectors have the property that they become inoperative for some time after detection event. We say the detector is blocked during this time.Blocking produces losses when using the detector as a photon-counter to detect a communications signal. In this paper, we characterize blocking losses for single detectors and for arrays of detectors. For arrays, we discuss conditions under which the output may be approximated as a Poisson point process, and provide a simple approximation to the blocking loss. We show how to extend the analysis to arrays of non-uniformly illuminated arrays.

  9. Dynamics and Synchronization of Semiconductor Lasers for Chaotic Optical Communications

    NASA Astrophysics Data System (ADS)

    Liu, Jia-Ming; Chen, How-Foo; Tang, Shuo

    The objective of this chapter is to provide a complete picture of the nonlinear dynamics and chaos synchronization of single-mode semiconductor lasers for chaotic optical communications. Basic concepts and theoretical framework are reviewed. Experimental results are presented to demonstrate the fundamental concepts. Numerical computations are employed for mapping the dynamical states and for illustrating certain detailed characteristics of the chaotic states. Three different semiconductor laser systems, namely, the optical injection system, the optical feedback system, and the optoelectronic feedback system, that are of most interest for high-bit-rate chaotic optical communications are considered. The optical injection system is a nonautonomous system that follows a period-doubling route to chaos. The optical feedback system is a phase-sensitive delayed-feedback autonomous system for which all three known routes, namely, period-doubling, quasiperiodicity, and intermittency, to chaos can be found. The optical feedback system is a phase-insensitive delayed-feedback autonomous system that follows a quasiperiodicity route to chaotic pulsing. Identical synchronization in unidirectionally coupled configurations is the focus of discussions for chaotic communications. For optical injection and optical feedback systems, the frequency, phase, and amplitude of the optical fields of both transmitter and receiver lasers are all locked in synchronism when complete synchronization is accomplished. For the optoelectronic feedback system, chaos synchronization involves neither the locking of the optical frequency nor the synchronization of the optical phase. For both optical feedback and optoelectronic feedback systems, where the transmitter is configured with a delayed feedback loop, anticipated and retarded synchronization can be observed as the difference between the feedback delay time and the propagation time from the transmitter laser to the receiver laser is varied. For a

  10. Compact optical transmitters for CubeSat free-space optical communications

    NASA Astrophysics Data System (ADS)

    Kingsbury, R. W.; Caplan, D. O.; Cahoy, K. L.

    2015-03-01

    We present the results of an architectural trade study and prototype implementation of an optical transmitter suitable for resource-constrained CubeSats. Recent advances in CubeSat attitude determination and control systems have made it possible to achieve three-axis stabilization. This is essential for laser communications systems, which have challenging pointing and stability requirements. Our downlink terminal design fits in a 10 cm x 10 cm x 5 cm volume, uses < 10W of power, weighs < 1 kg, and supports data rates up to 50 Mbps. The terminal incorporates pointing, tracking and acquisition optics, an optical fine-steering mechanism, and a compact transmitter. This work focuses on the development of the transmitter for the Nanosatellite Optical Downlink Experiment (NODE). Two transmitter architectures were considered initially: direct modulation of a high-power laser diode and a master oscillator power amplifier (MOPA). The MOPA-based approach was selected and a prototype "breadboard" was built from commercially available components. The prototype transmitter produces high fidelity (extinction ratio, ER < 33 dB) pulse position modulation (PPM) waveforms at 1550nm with 200mW average output power while consuming 6:5W of electrical power.

  11. Composite-embedded optical fibers for communication links

    NASA Astrophysics Data System (ADS)

    Morgan, R. E.; Mitkus, V. V.; Jones, K. J.; Hixson, R. L.

    1989-12-01

    A design concept is examined in which fiber optics embedded in a composite material for avionics packaging will serve as communication links (rather than as stress sensors as in so called 'smart skins/structures'). Attention is given to the material processing technologies, optical fibers, connectors, and composite materials suitable for this purpose. It is emphasized that embedded optical fibers will make it possible to increase signal throughput and the security from EMI/EMP, and will become part of the avionic structure without affecting its shape and volume (or significantly increase its weight).

  12. Design of fiber-optic digital communication systems. Introductory course for students in communications engineering

    NASA Astrophysics Data System (ADS)

    Eftimov, T. A.

    1991-04-01

    The handbook intends to provide the basic concepts about the components necessary to design a fiber-optic link and the communication system itself. A student or a beginner in optical fiber communications is introduced to the basic concepts, characteristics, and parameters of the components from a practical point of view. Therefore, the text is heavily illustrated. The mathematics involved is reduced to the absolute minimum and all of the calculations can be performed with a simple pocket calculator. Unlike most university textbooks, the practical parameters of devices needed as ordering information are specially outlined. Special attention was paid to simplified design examples of the most typical up-to-date digital communication systems. These together with the problems should help the student acquire the minimum but solid knowledge in this so rapidly developing communications world.

  13. Optical Communications Link to Airborne Transceiver

    NASA Technical Reports Server (NTRS)

    Regehr, Martin W.; Kovalik, Joseph M.; Biswas, Abhijit

    2011-01-01

    An optical link from Earth to an aircraft demonstrates the ability to establish a link from a ground platform to a transceiver moving overhead. An airplane has a challenging disturbance environment including airframe vibrations and occasional abrupt changes in attitude during flight. These disturbances make it difficult to maintain pointing lock in an optical transceiver in an airplane. Acquisition can also be challenging. In the case of the aircraft link, the ground station initially has no precise knowledge of the aircraft s location. An airborne pointing system has been designed, built, and demonstrated using direct-drive brushless DC motors for passive isolation of pointing disturbances and for high-bandwidth control feedback. The airborne transceiver uses a GPS-INS system to determine the aircraft s position and attitude, and to then illuminate the ground station initially for acquisition. The ground transceiver participates in link-pointing acquisition by first using a wide-field camera to detect initial illumination from the airborne beacon, and to perform coarse pointing. It then transfers control to a high-precision pointing detector. Using this scheme, live video was successfully streamed from the ground to the aircraft at 270 Mb/s while simultaneously downlinking a 50 kb/s data stream from the aircraft to the ground.

  14. Channel simulation for direct-detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct-detection optical communication system. The system is capable of providing signal fading statistics which obey log-normal, beta, Rayleigh, Ricean, or chi-square density functions. Experimental tests of the performance of the channel simulator are presented.

  15. Channel simulation for direct detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct detection optical communication system. The system is capable of providing signal fading statistics which obey log normal, beta, Rayleigh, Ricean or chi-squared density functions. Experimental tests of the performance of the Channel Simulator are presented.

  16. Various Analyses of Structures and Systems Pertaining to Optical Communications

    NASA Technical Reports Server (NTRS)

    Petersen, Collin W.

    2005-01-01

    The Optical Communications Group intends to experiment with a 2 by 2 meter Fresnel lens to determine its likelihood as an alternative to focusing mirrors for optical communications. The lens was delivered in four sections. A support structure was required for the lens in order to hold the four sections in a single flat plane with an adjustable degree angle. In order to use the 200-in. Hale telescope for optical communications purposes, an optical filter membrane must used to pass the communications wavelength while blocking sunlight wavelengths. This filter must withstand wind gusts of up to 50 miles per hour. Stress analysis predicts that the membrane will survive with a safety factor greater than two. The methods used were verified by pressure testing the material. Mechanical and thermodynamic analyses were performed on a simple Golay cell in order to optimize its dimensions for best performance. Flexures are examined as an inexpensive alternative to traditional methods for kinematically constraining a 1.5-meter spherical mirror.

  17. Underwater Wireless Optical Communication System Using Blue LEDs

    NASA Astrophysics Data System (ADS)

    Lin, Aobo; Tong, Zheng; Song, Yuhang; Kong, Meiwei; Xu, Jing

    2016-02-01

    We demonstrate a self-designed underwater wireless optical communication system using blue LEDs. The performance of the transmitter and receiver was experimentally investigated. Four different square wave signals (10 KHz, 100 KHz, 500 KHz and 1 MHz) were successfully transmitted via a short water channel at the first phase.

  18. Kansas Communication and Instruction System through Fiber-Optic Transmission.

    ERIC Educational Resources Information Center

    Kansas State Dept. of Education, Topeka.

    Schools and communities will restructure as they move into the next decade. The success of this restructuring will be dependent upon access to and sharing of quality teaching and information through an expanded communication system. One of the major two-way interactive technologies is the fiber-optic cable: a delivery system that will provide…

  19. Graphene-based qubits in quantum communications

    NASA Astrophysics Data System (ADS)

    Wu, G. Y.; Lue, N.-Y.

    2012-07-01

    We explore the potential application of graphene-based qubits in photonic quantum communications. In particular, the valley pair qubit in double quantum dots of gapped graphene is investigated as a quantum memory in the implementation of quantum repeaters. For the application envisioned here, our work extends the recent study of the qubit [Wu , arXiv:1104.0443; Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.84.195463 84, 195463 (2011)] to the case where the qubit is placed in an in-plane magnetic field configuration. It develops, for the configuration, a method of qubit manipulation, based on a unique ac electric field-induced, valley-orbit interaction-derived mechanism in gapped graphene. It also studies the optical response of graphene quantum dots in the configuration, in terms of valley excitation with respect to photonic polarization, and illustrates faithful photon ↔ valley quantum state transfers. This work suggests the interesting prospect of an all-graphene approach for the solid state components of a quantum network, e.g., quantum computers and quantum memories in communications.

  20. Model of Atmospheric Links on Optical Communications from High Altitude

    NASA Technical Reports Server (NTRS)

    Subich, Christopher

    2004-01-01

    Optical communication links have the potential to solve many of the problems of current radio and microwave links to satellites and high-altitude aircraft. The higher frequency involved in optical systems allows for significantly greater signal bandwidth, and thus information transfer rate, in excess of 10 Gbps, and the highly directional nature of laser-based signals eliminates the need for frequency-division multiplexing seen in radio and microwave links today. The atmosphere, however, distorts an optical signal differently than a microwave signal. While the ionosphere is one of the most significant sources of noise and distortion in a microwave or radio signal, the lower atmosphere affects an optical signal more significantly. Refractive index fluctuations, primarily caused by changes in atmospheric temperature and density, distort the incoming signal in both deterministic and nondeterministic ways. Additionally, suspended particles, such as those in haze or rain, further corrupt the transmitted signal. To model many of the atmospheric effects on the propagating beam, we use simulations based on the beam-propagation method. This method, developed both for simulation of signals in waveguides and propagation in atmospheric turbulence, separates the propagation into a diffraction and refraction problem. The diffraction step is an exact solution, within the limits of numerical precision, to the problem of propagation in free space, and the refraction step models the refractive index variances over a segment of the propagation path. By applying refraction for a segment of the propagation path, then diffracting over that same segment, this method forms a good approximation to true propagation through the atmospheric medium. Iterating over small segments of the total propagation path gives a good approximation to the problem of propagation over the entire path. Parameters in this model, such as initial beam profile and atmospheric constants, are easily modified in a

  1. MEMS technology and explosive growth fiber optical communication

    NASA Astrophysics Data System (ADS)

    Liu, Ai Q.

    2001-10-01

    Silicon micromachines are an emerging technology that will impact almost every area of science and technology. From industries as diverse as automotive, cellular, aerospace, chemical as well as lightwave systems, N/MEMS (Nano/Microelectromechanical Systems) is rapidly becoming the solution of choice for many technical problems. MEMS devices are, in general, built using standard IC techniques. Starting with a silicon wafer and depositing a series of films such as nitrides, polysilicon, oxides and metals, one builds a complex three-dimensional structure in much the same way one builds an IC. However, unlike an IC, one then releases the device by etching away the oxides, producing a structure that can move. This subtle change in processing allows one to produce devices that move including rotary gears, hinges, plates, flexural beams and motors of every imaginable type. In optical fiber communication, MEMS allows one to build a wide range of components including data modulators, variable attenuators, optical switches, active equalizers, add/drop multiplexers, optical crossconnects (OXCs), dispersion compensators, all- optical switches, tunable laser sources, active packages and adaptive optical elements. In this paper, the design and fabrication of MEMS optical devices using readily available standard fabrication facilities for different fiber optical communication applications will be discussed in details.

  2. Critical reviews of fiber-optic communication technology Optical fibers

    NASA Astrophysics Data System (ADS)

    Kapron, F. P.

    The review begins with brief highlights of the history of fiber optics, followed by a discussion of the attributes of shortwave and longwave transmission. This leads to an investigation of various fiber types, short-haul considerations, and then single-mode aspects. Specialty fiber is briefly covered, followed by a survey of several research trends today that will lead to new systems capabilities in the future. No references are given, since hundreds would be necessary to make the list even partially complete.

  3. Applications of optical switches in fiber optic communication networks

    NASA Astrophysics Data System (ADS)

    Hanson, Daniel; Gosset, Nathalie M.

    1991-01-01

    The growing deployment of fiber optics which are vulnerable to single point failure creates an urgent need for a means of automatic protection switching test access and reconfiguration in telephone networks. Fiber switching is a technology which is beginning to be used in trunk and subscriber ioop applications to satisfy this need. This paper focuses on several applications of fiber switching in public networks including the economic and technical advantages of this technology.

  4. Effects of unwanted feedback on synchronized chaotic optical communications

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Pan, Wei; Luo, Bin; Ma, Dong

    2006-04-01

    The effects of unwanted external optical feedback on synchronized chaotic optical communication systems are studied numerically. We consider an open-loop configuration consisting of a transmitter laser with double external optical feedbacks and a receiver laser with optical injection from the transmitter laser. First, including the effects of unwanted optical feedback, the synchronization performances of both the complete synchronization and the generalized synchronization are examined. Then the encoding and decoding performances of the generalized synchronization and the effects of the introduced feedback are investigated, respectively. Finally, we study the control of the unwanted feedback on the dynamics of the transmitter laser and briefly discuss the system security when the transmitter laser is driven to operate in a steady state or periodic oscillation state by the additional feedback.

  5. Interface between an optical communications system and the host spacecraft

    NASA Astrophysics Data System (ADS)

    Barry, J. D.

    1988-06-01

    The current state of development of optical communications systems for intersatellite data transfer has reached an advanced level, with on-orbit operations planned for the early 1990s. The technology and engineering aspects of the development of the optical system have been evaluated in some detail and are widely known, but the interfaces between the optical system and the host spacecraft are not as well understood. Many aspects of the optical interfaces have been identified, are currently under investigation and are discussed here. These include the interface support needed from the host spacecraft, such as thermal, electrical, mechanical, optical, radiation protection and contamination control; spacecraft attitude and vibrational stability; spacecraft level interface testing, such as EMI/EMC, vibration and thermal vacuum tests; and lifetime and reliability testing.

  6. Optical communication beyond orbital angular momentum.

    PubMed

    Trichili, Abderrahmen; Rosales-Guzmán, Carmelo; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-01-01

    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks. PMID:27283799

  7. Optical communication beyond orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Trichili, Abderrahmen; Rosales-Guzmán, Carmelo; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-06-01

    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks.

  8. Optical communication beyond orbital angular momentum

    PubMed Central

    Trichili, Abderrahmen; Rosales-Guzmán, Carmelo; Dudley, Angela; Ndagano, Bienvenu; Ben Salem, Amine; Zghal, Mourad; Forbes, Andrew

    2016-01-01

    Mode division multiplexing (MDM) is mooted as a technology to address future bandwidth issues, and has been successfully demonstrated in free space using spatial modes with orbital angular momentum (OAM). To further increase the data transmission rate, more degrees of freedom are required to form a densely packed mode space. Here we move beyond OAM and demonstrate multiplexing and demultiplexing using both the radial and azimuthal degrees of freedom. We achieve this with a holographic approach that allows over 100 modes to be encoded on a single hologram, across a wide wavelength range, in a wavelength independent manner. Our results offer a new tool that will prove useful in realizing higher bit rates for next generation optical networks. PMID:27283799

  9. Initial Characterization of Optical Communications with Disruption-Tolerant Network Protocols

    NASA Technical Reports Server (NTRS)

    Schoolcraft, Joshua; Wilson, Keith

    2011-01-01

    Disruption-tolerant networks (DTNs) are groups of network assets connected with a suite of communication protocol technologies designed to mitigate the effects of link delay and disruption. Application of DTN protocols to diverse groups of network resources in multiple sub-networks results in an overlay network-of-networks with autonomous data routing capability. In space environments where delay or disruption is expected, performance of this type of architecture (such as an interplanetary internet) can increase with the inclusion of new communications mediums and techniques. Space-based optical communication links are therefore an excellent building block of space DTN architectures. When compared to traditional radio frequency (RF) communications, optical systems can provide extremely power-efficient and high bandwidth links bridging sub-networks. Because optical links are more susceptible to link disruption and experience the same light-speed delays as RF, optical-enabled DTN architectures can lessen potential drawbacks and maintain the benefits of autonomous optical communications over deep space distances. These environment-driven expectations - link delay and interruption, along with asymmetric data rates - are the purpose of the proof-of-concept experiment outlined herein. In recognizing the potential of these two technologies, we report an initial experiment and characterization of the performance of a DTN-enabled space optical link. The experiment design employs a point-to-point free-space optical link configured to have asymmetric bandwidth. This link connects two networked systems running a DTN protocol implementation designed and written at JPL for use on spacecraft, and further configured for higher bandwidth performance. Comparing baseline data transmission metrics with and without periodic optical link interruptions, the experiment confirmed the DTN protocols' ability to handle real-world unexpected link outages while maintaining capability of

  10. Design Reference Missions for Deep-Space Optical Communication

    NASA Astrophysics Data System (ADS)

    Breidenthal, J.; Abraham, D.

    2016-05-01

    We examined the potential, but uncertain, NASA mission portfolio out to a time horizon of 20 years, to identify mission concepts that potentially could benefit from optical communication, considering their communications needs, the environments in which they would operate, and their notional size, weight, and power constraints. A set of 12 design reference missions was selected to represent the full range of potential missions. These design reference missions span the space of potential customer requirements, and encompass the wide range of applications that an optical ground segment might eventually be called upon to serve. The design reference missions encompass a range of orbit types, terminal sizes, and positions in the solar system that reveal the chief system performance variables of an optical ground segment, and may be used to enable assessments of the ability of alternative systems to meet various types of customer needs.

  11. Photon counting detector array algorithms for deep space optical communications

    NASA Astrophysics Data System (ADS)

    Srinivasan, Meera; Andrews, Kenneth S.; Farr, William H.; Wong, Andre

    2016-03-01

    For deep-space optical communications systems utilizing an uplink optical beacon, a single-photon-counting detector array on the flight terminal can be used to simultaneously perform uplink tracking and communications as well as accurate downlink pointing at photon-starved (pW=m2) power levels. In this paper, we discuss concepts and algorithms for uplink signal acquisition, tracking, and parameter estimation using a photon-counting camera. Statistical models of detector output data and signal processing algorithms are presented, incorporating realistic effects such as Earth background and detector/readout blocking. Analysis and simulation results are validated against measured laboratory data using state-of-the-art commercial photon-counting detector arrays, demonstrating sub-microradian tracking errors under channel conditions representative of deep space optical links.

  12. Micromachined modulator arrays for use in free-space optical communication systems

    NASA Astrophysics Data System (ADS)

    Lewis, Keith L.; Ridley, Kevin D.; McNie, Mark E.; Smith, Gilbert W.; Scott, Andrew M.

    2004-12-01

    A summary is presented of some of the design criteria relevant to the realisation of silicon micromachined modulator arrays for use in free-space optical communication systems. Theoretical performance levels achievable are compared with values measured on experimental devices produced using a modified Multi-User MEMS Process (MUMPS). Devices capable of realising modulation rates in excess of 300 kHz are described and their optical characteristics compared with published data on devices based on multiple quantum well technology.

  13. Few-mode fiber based optical sensors.

    PubMed

    Li, An; Wang, Yifei; Hu, Qian; Shieh, William

    2015-01-26

    Few-mode fibers (FMFs) have found applications in optical communications and sensors with attractive features that standard single mode fiber (SSMF) do not possess. We report our recent progress on FMF based optical sensors, and show the potential of utilizing the spatial dimension for multi-parameter sensing with discrimination capability. We first show a discrete type FMF sensor based on interferometer structure with a short FMF, utilizing the modal interference between either the polarizations (x and y) or the spatial modes (LP(01) and LP(11)). We then show a distributed type FMF sensor by generating the stimulated Brillouin scattering (SBS) in a long FMF. We characterize the Brillouin gain spectrum (BGS) with a pump-probe configuration, and measure the temperature and strain coefficients for LP(01) and LP(11) modes. The proposed FMF based optical sensor can be applied to sensing a wide range of parameters. PMID:25835874

  14. Swarm intelligence for atmospheric compensation in free space optical communication-Modified shuffled frog leaping algorithm

    NASA Astrophysics Data System (ADS)

    Li, Zhaokun; Cao, Jingtai; Zhao, Xiaohui; Liu, Wei

    2015-03-01

    A conventional adaptive optics (AO) system is widely used to compensate atmospheric turbulence in free space optical (FSO) communication systems, but wavefront measurements based on phase-conjugation principle are not desired under strong scintillation circumstances. In this study we propose a novel swarm intelligence optimization algorithm, which is called modified shuffled frog leaping algorithm (MSFL), to compensate the wavefront aberration. Simulation and experiments results show that MSFL algorithm performs well in the atmospheric compensation and it can increase the coupling efficiency in receiver terminal and significantly improve the performance of the FSO communication systems.

  15. Secure optical communication system utilizing deformable MEMS mirrors

    NASA Astrophysics Data System (ADS)

    Ziph-Schatzberg, Leah; Bifano, Thomas; Cornelissen, Steven; Stewart, Jason; Bleier, Zvi

    2009-02-01

    An optical communication system suitable for voice, data retrieval from remote sensors and identification is described. The system design allows operation at ranges of several hundred meters. The heart of the system is a modulated MEMS mirror that is electrostatically actuated and changes between a flat reflective state and a corrugated diffractive state. A process for mass producing these mirrors at low cost was developed and is described. The mirror was incorporated as a facet in a hollow retro-reflector, allowing temporal modulation of an interrogating beam and the return of the modulated beam to the interrogator. This system thus consists of a low power, small and light communication node with large (about 60°) angular extent. The system's range and pointing are determined by the interrogator /detector/demodulator (Transceiver) unit. The transceiver is comprised of an optical channel to establish line of sight communication, an interrogating laser at 1550nm, an avalanche photo diode to detect the return signal and electronics to drive the laser and demodulate the detected signal and convert it to an audio signal. A functional prototype system was built using a modified compact optical sight as the transceiver. Voice communication in free space was demonstrated. The design and test of major components and the complete system are discussed.

  16. The research of high efficient optical fiber coupling technology in space laser communication

    NASA Astrophysics Data System (ADS)

    Wang, Hao-zeng; Tong, Shou-feng; Zhang, Lei; Yang, Hong-kun

    2013-08-01

    With the development of optical fiber communications, especially the maturity of the optical amplifiers and the WDM technology, space optical communication at 1550 nm becomes a promising solution for future high speed satellite communication. Receiving technology with optical amplifiers and coupling space light into single mode fiber are key technologies in space optical communication at 1550 nm. Free-space-to-fiber coupling technique investigated in this paper is the first challenge of applying fiber communication techniques to free space optical communications. We analyzed the factors that affect the efficiency of free-space-to single-mode-fiber coupling based on mode-matching theory of electromagnetic fields. On this objective, in this paper, the theoretical analysis of the effect of atmospheric turbulence on the space light-single mode fiber coupling efficiency is discussed. On this basis, the short-distance experiment coupling space light into single mode fiber is carried out. 1. The main factors affecting the process coupling space light into single mode fiber are analyzed. This paper introduced the statistical theory of atmospheric turbulence and gave out the main turbulence parameters and meteyard based on the theory of the space light-single mode fiber coupling efficiency under ideal conditions. 2. The influence of atmospheric turbulence on the space light-single mode fiber coupling efficiency is analyzed and simulated. In the weak turbulence condition, mathematical model of the mean coupling efficiency and its fluctuation variance was given. And the fluctuation variance of coupling efficiency was simulated studied under the atmospheric conditions. The influences on the average coupling efficiency was theoretically studied, which were induced by the structure constant of atmospheric refractive index, the diameter of coupling lens and the single-mode fiber mode field radius. 3. Validating the theoretical model by a experiment under a short link coupling

  17. Experimental multiplexing of quantum key distribution with classical optical communication

    NASA Astrophysics Data System (ADS)

    Wang, Liu-Jun; Chen, Luo-Kan; Ju, Lei; Xu, Mu-Lan; Zhao, Yong; Chen, Kai; Chen, Zeng-Bing; Chen, Teng-Yun; Pan, Jian-Wei

    2015-02-01

    We demonstrate the realization of quantum key distribution (QKD) when combined with classical optical communication, and synchronous signals within a single optical fiber. In the experiment, the classical communication sources use Fabry-Pérot (FP) lasers, which are implemented extensively in optical access networks. To perform QKD, multistage band-stop filtering techniques are developed, and a wavelength-division multiplexing scheme is designed for the multi-longitudinal-mode FP lasers. We have managed to maintain sufficient isolation among the quantum channel, the synchronous channel and the classical channels to guarantee good QKD performance. Finally, the quantum bit error rate remains below a level of 2% across the entire practical application range. The proposed multiplexing scheme can ensure low classical light loss, and enables QKD over fiber lengths of up to 45 km simultaneously when the fibers are populated with bidirectional FP laser communications. Our demonstration paves the way for application of QKD to current optical access networks, where FP lasers are widely used by the end users.

  18. EMC noise free endoscope using optical fiber communication technology

    NASA Astrophysics Data System (ADS)

    Kubo, Wataru; Minakuchi, Tadashi; Sato, Koichi; Tsutamura, Koichi; Syoji, Takaaki; Sugitani, Kazuo; Arimoto, Akira; Arai, Shinichi

    2008-02-01

    Recently, the number of pixels of an image sensor has reached more than one Mega in the field of video endoscopes, while analog signal transmission bands that use existing electric wires will face physical limitations from the perspective of signal bandwidth and EMC (Electro Magnetic Compatibility) noise. In order to solve these problems, we have developed a bi-directional digital optical communication endoscope system that employs both an image sensor and a single line optical fiber. In addition, due to the fiber's high-speed image signal transmission, we have incorporated a digital circuit for serial modulation and deserial demodulation. Consequently, we confirmed that transmission speeds of a 1Gbps downlink image signal and a 110Kbps uplink control signal were achieved as a result of simultaneous communication. We also designed and tested a compact, co-axial bi-directional optical transmitter and receiver module that can be built into the distal side of a scope. The optical communication module size is less than φ4×10mm. It was confirmed that this module could be installed in the distal side of a current endoscope.

  19. Experimental multiplexing of quantum key distribution with classical optical communication

    SciTech Connect

    Wang, Liu-Jun; Chen, Luo-Kan; Ju, Lei; Xu, Mu-Lan; Zhao, Yong; Chen, Kai; Chen, Zeng-Bing; Chen, Teng-Yun Pan, Jian-Wei

    2015-02-23

    We demonstrate the realization of quantum key distribution (QKD) when combined with classical optical communication, and synchronous signals within a single optical fiber. In the experiment, the classical communication sources use Fabry-Pérot (FP) lasers, which are implemented extensively in optical access networks. To perform QKD, multistage band-stop filtering techniques are developed, and a wavelength-division multiplexing scheme is designed for the multi-longitudinal-mode FP lasers. We have managed to maintain sufficient isolation among the quantum channel, the synchronous channel and the classical channels to guarantee good QKD performance. Finally, the quantum bit error rate remains below a level of 2% across the entire practical application range. The proposed multiplexing scheme can ensure low classical light loss, and enables QKD over fiber lengths of up to 45 km simultaneously when the fibers are populated with bidirectional FP laser communications. Our demonstration paves the way for application of QKD to current optical access networks, where FP lasers are widely used by the end users.

  20. A Modern and Interactive Approach to Learning Laser and Optical Communications.

    ERIC Educational Resources Information Center

    Minasian, Robert; Alameh, Kamal

    2002-01-01

    Discusses challenges in teaching lasers and optical communications to engineers, including the prohibitive cost of laboratory experiments, and describes the development of a computer-based photonics simulation experiment module which provides students with an understanding and visualization of how lasers can be modulated in telecommunications.…

  1. Development of the Optical Communications Telescope Laboratory: A Laser Communications Relay Demonstration Ground Station

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Antsos, D.; Roberts, L. C. Jr.,; Piazzolla, S.; Clare, L. P.; Croonquist, A. P.

    2012-01-01

    The Laser Communications Relay Demonstration (LCRD) project will demonstrate high bandwidth space to ground bi-directional optical communications links between a geosynchronous satellite and two LCRD optical ground stations located in the southwestern United States. The project plans to operate for two years with a possible extension to five. Objectives of the demonstration include the development of operational strategies to prototype optical link and relay services for the next generation tracking and data relay satellites. Key technologies to be demonstrated include adaptive optics to correct for clear air turbulence-induced wave front aberrations on the downlink, and advanced networking concepts for assured and automated data delivery. Expanded link availability will be demonstrated by supporting operations at small sun-Earth-probe angles. Planned optical modulation formats support future concepts of near-Earth satellite user services to a maximum of 1.244 Gb/s differential phase shift keying modulation and pulse position modulations formats for deep space links at data rates up to 311 Mb/s. Atmospheric monitoring instruments that will characterize the optical channel during the link include a sun photometer to measure atmospheric transmittance, a solar scintillometer, and a cloud camera to measure the line of sight cloud cover. This paper describes the planned development of the JPL optical ground station.

  2. Negative Avalanche Feedback Detectors for Photon-Counting Optical Communications

    NASA Technical Reports Server (NTRS)

    Farr, William H.

    2009-01-01

    Negative Avalanche Feedback photon counting detectors with near-infrared spectral sensitivity offer an alternative to conventional Geiger mode avalanche photodiode or phototube detectors for free space communications links at 1 and 1.55 microns. These devices demonstrate linear mode photon counting without requiring any external reset circuitry and may even be operated at room temperature. We have now characterized the detection efficiency, dark count rate, after-pulsing, and single photon jitter for three variants of this new detector class, as well as operated these uniquely simple to use devices in actual photon starved free space optical communications links.

  3. Fiber optic self healing ring for power system communications

    SciTech Connect

    Phillippe, T.A.

    1995-12-31

    A 138kv system, consisting of ten transmission lines and eight substations were upgraded with a new communications system to improve the monitoring, protection and control functions, as well as to eliminate the requirements for leased lines from the telephone companies. Fiber optic communications were chosen to take advantage of fiber`s immunity to noise, large bandwidth capability, flexibility, and other characteristics. SONET transmission equipment was chosen to take advantage of the newest technology available, and to allow maximum capability for future expansion.

  4. Results from the Galileo Laser Uplink: A JPL Demonstration of Deep-Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Lesh, J. R.

    1993-01-01

    The successful completion of the Galileo Optical Experiment (GOPEX), represented the accomplishment of a significant milestone in JPL's optical communication plan. The experiment demonstrated the first transmission of a narrow laser beam to a deep-space vehicle. Laser pulses were beamed to the Galileo spacecraft by Earth-based transmitters at the Table Mountain Facility (TMF), California, and Starfire Optical Range (SOR), New Mexico. The experiment took place over an eight-day period (December 9 through December 16, 1992) as Galileo receded from Earth on its way to Jupiter, and covered ranges from 1 to 6 million kilometers (15 times the Earth-Moon distance), the laser uplink from TMF covered the longest known range for laser beam transmission and detection. This demonstration is the latest in a series of accomplishments by JPL in the development of deep-space optical communications technology.

  5. Frequency doubling conversion efficiencies for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Shelton, R. L.

    1987-01-01

    The theory of optical frequency doubling conversion efficiency is analyzed for the small signal input case along with the strong signal depleted input case. Angle phase matching and beam focus spot size are discussed and design trades are described which maximize conversion efficiency. Experimental conversion efficiencies from the literature, which are less than theoretical results at higher input intensities due to saturation, reconversion, and higher order processes, are applied to a case study of an optical communications link from Saturn. Double pass conversion efficiencies as high as 45 percent are expected. It is believed that even higher conversion efficiencies can be obtained using multipass conversion.

  6. Optical communications systems and technology for deep-space exploration

    NASA Technical Reports Server (NTRS)

    Lesh, James R.

    1989-01-01

    An account is given of architectural and implementational strategies for the creation of planetary and other deep-space optical communications networks, with a view to the developmental requirements of both planetary spacecraft subsystems and an earth-vicinity reception system. Attention is given to prospective technology-development challenges. An open-loop spatial acquisition process is defined, in conjunction with a terrestrial, large-aperture/low-cost 'photon bucket' optical reception telescopic system having an integral, axially-aligned tube-bundle sunshield. An efficient diode-pumped Nd:YAG laser is envisioned as the transmitter.

  7. Optical Communication Transceiver For X2000; Second Delivery Program

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Lesh, J. R.

    2000-01-01

    Conceptual-design of a multi-functional optical instrument is underway for the X2000 - Second Delivery Program. The transceiver will perform both free-space optical- communication and science imaging by sharing a common 10-cm aperture telescope. A single focal-plane array (such as, APS-Active Pixel Sensor) in conjunction with a filter wheel will be used to perform the two functions. Targeted values for the transceiver's weight and power consumption are: 4 Kg, and 14 W. This transceiver would be capable of delivering greater than IO Kbps to a 3.5-m diameter receiving station from the range of 2 AU during day-time.

  8. Optical intersatellite links - Application to commercial satellite communications

    NASA Technical Reports Server (NTRS)

    Paul, D.; Faris, F.; Garlow, R.; Inukai, T.; Pontano, B.; Razdan, R.; Ganz, Aura; Caudill, L.

    1992-01-01

    Application of optical intersatellite links for commercial satellite communications services is addressed in this paper. The feasibility of commercialization centers around basic issues such as the need and derived benefits, implementation complexity and overall cost. In this paper, commercialization of optical ISLs is assessed in terms of the services provided, systems requirements and feasibility of appropriate technology. Both long- and short-range ISLs for GEO-GEO, GEO-LEO and LEO applications are considered. Impact of systems requirements on the payload design and use of advanced technology in reducing its mass, power, and volume requirements are discussed.

  9. Orion Optical Navigation for Loss of Communication Lunar Return Contingencies

    NASA Technical Reports Server (NTRS)

    Getchius, Joel; Hanak, Chad; Kubitschek, Daniel G.

    2010-01-01

    The Orion Crew Exploration Vehicle (CEV) will replace the Space Shuttle and serve as the next-generation spaceship to carry humans back to the Moon for the first time since the Apollo program. For nominal lunar mission operations, the Mission Control Navigation team will utilize radiometric measurements to determine the position and velocity of Orion and uplink state information to support Lunar return. However, in the loss of communications contingency return scenario, Orion must safely return the crew to the Earth's surface. The navigation design solution for this loss of communications scenario is optical navigation consisting of lunar landmark tracking in low lunar orbit and star- horizon angular measurements coupled with apparent planetary diameter for Earth return trajectories. This paper describes the optical measurement errors and the navigation filter that will process those measurements to support navigation for safe crew return.

  10. Free space optical communications through clouds: analysis of signal characteristics.

    PubMed

    Wu, Binbin; Hajjarian, Zeinab; Kavehrad, Mohsen

    2008-06-10

    Free space optical communications (FSOC) is a method by which one transmits a modulated beam of light through the atmosphere for broadband applications. Fundamental limitations of FSOC arise from the environment through which light propagates. This work addresses transmitted light beam dispersion (spatial, angular, and temporal dispersion) in FSOC operating as a ground-to-air link when clouds exist along the communications channel. Light signals (photons) transmitted through clouds will interact with the cloud particles. Photon-particle interaction causes dispersion of light signals, which has significant effects on signal attenuation and pulse spread. The correlation between spatial and angular dispersion is investigated as well, which plays an important role on the receiver design. Moreover, the paper indicates that temporal dispersion (pulse spread) and energy loss strongly depend on the aperture size of the receiver, the field-of-view (FOV), and the position of the receiver relative to the optical axis of the transmitter. PMID:18545290

  11. A novel RS BTC coding scheme for optical communications

    NASA Astrophysics Data System (ADS)

    Yuan, Jian-guo; Jia, Yue-xing; Hu, Yun-xia

    2012-07-01

    A novel Reed Solomon (RS) block turbo code (BTC) coding scheme of RS(63,58)×RS(63,58) for optical communications is proposed. The simulation results show that the net coding gain (NCG) of this scheme at the sixth iteration is more than that of other coding schemes at the third iteration for the bit error rate (BER) of 10-12. Furthermore, the novel RS BTC has shorter component code and rapider encoding and decoding speed. Therefore, the novel RS BTC coding scheme can be better used in high-speed long-haul optical communication systems, and the novel RS BTC can be regarded as a candidate code of the super forward error correction (super-FEC) code. Moreover, the encoding/decoding design and implementation of the novel RS BTC are also presented

  12. Visible light communication based motion detection.

    PubMed

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon-Ho

    2015-07-13

    In this paper, a unique and novel visible light communication based motion detection is presented. The proposed motion detection is performed based on white light LEDs and an array of photodetectors from existing visible light communication (VLC) links, thus providing VLC with three functionalities of illumination, communication and motion detection. The motion is detected by observing the pattern created by intentional obstruction of the VLC link. Experimental and simulation results demonstrate the validity of the proposed VLC based motion detection technique. The VLC based motion detection can benefit smart devices control in VLC based smart home environments. PMID:26191937

  13. Determining the feasibility of Free Space Optical Communication in Namibia

    NASA Astrophysics Data System (ADS)

    Handura, M. R.; Ndjavera, K. M.; Nyirenda, C. N.; Olwal, T. O.

    2016-05-01

    Namibia has a great potential for Free Space Optical Communication (FSOC) because of its clear skies. This paper determines the feasibility of FSOC in Namibia by using theoretical models. Visibility, wind speed, and altitude data for several locations are used to compute atmospheric losses under average and worst case atmospheric conditions. Optimal FSOC link distances for all the locations are determined under both conditions by evaluating each location's atmospheric loss against the power link margin. Results show that under average conditions, an FSOC optimal link distance of up to 7500 m can be achieved for inland locations. On the other hand, Grootfontein and Katima Mulilo, at 6900 m, have the longest distance under worst case atmospheric conditions. Walvis Bay has the shortest FSOC link distances of 3224 m and 2500 m under average and worst case conditions respectively. This study shows that FSOC in Namibia is feasible for last mile broadband access networks, where link distances are generally less than 10 km. These results are based on theoretical models, which have taken into account reasonable realistic assumptions. Practical field tests using FSOC equipment will be conducted as part of future work. Comparisons will be made with theoretical results obtained in this study.

  14. Optical communication system performance with tracking error induced signal fading.

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.; Premo, D. A.

    1973-01-01

    System performance is determined for an optical communication system using noncoherent detection in the presence of tracking error induced signal fading assuming (1) binary on-off modulation (OOK) with both fixed and adaptive threshold receivers, and (2) binary polarization modulation (BPM). BPM is shown to maintain its inherent 2- to 3-dB advantage over OOK when adaptive thresholding is used, and to have a substantially greater advantage when the OOK system is restricted to a fixed decision threshold.

  15. Comparison of swarm intelligence algorithms in atmospheric compensation for free space optical communication

    NASA Astrophysics Data System (ADS)

    Li, Zhaokun; Cao, Jingtai; Liu, Wei; Feng, Jianfeng; Zhao, Xiaohui

    2015-03-01

    We use conventional adaptive optical system to compensate atmospheric turbulence in free space optical (FSO) communication system under strong scintillation circumstances, undesired wave-front measurements based on Shark-Hartman sensor (SH). Since wavefront sensor-less adaptive optics is a feasible option, we propose several swarm intelligence algorithms to compensate the wavefront aberration from atmospheric interference in FSO and mainly discuss the algorithm principle, basic flows, and simulation result. The numerical simulation experiment and result analysis show that compared with SPGD algorithm, the proposed algorithms can effectively restrain wavefront aberration, and improve convergence rate of the algorithms and the coupling efficiency of receiver in large extent.

  16. An Array of Optical Receivers for Deep-Space Communications

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Chi-Wung; Srinivasan, Meera; Andrews, Kenneth

    2007-01-01

    An array of small optical receivers is proposed as an alternative to a single large optical receiver for high-data-rate communications in NASA s Deep Space Network (DSN). Because the telescope for a single receiver capable of satisfying DSN requirements must be greater than 10 m in diameter, the design, building, and testing of the telescope would be very difficult and expensive. The proposed array would utilize commercially available telescopes of 1-m or smaller diameter and, therefore, could be developed and verified with considerably less difficulty and expense. The essential difference between a single-aperture optical-communications receiver and an optical-array receiver is that a single-aperture receiver focuses all of the light energy it collects onto the surface of an optical detector, whereas an array receiver focuses portions of the total collected energy onto separate detectors, optically detects each fractional energy component, then combines the electrical signal from the array of detector outputs to form the observable, or "decision statistic," used to decode the transmitted data. A conceptual block diagram identifying the key components of the optical-array receiver suitable for deep-space telemetry reception is shown in the figure. The most conspicuous feature of the receiver is the large number of small- to medium-size telescopes, with individual apertures and number of telescopes selected to make up the desired total collecting area. This array of telescopes is envisioned to be fully computer- controlled via the user interface and prediction-driven to achieve rough pointing and tracking of the desired spacecraft. Fine-pointing and tracking functions then take over to keep each telescope pointed toward the source, despite imperfect pointing predictions, telescope-drive errors, and vibration caused by wind.

  17. Low-Cost Large Aperture Telescopes for Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    2006-01-01

    Low-cost, 0.5-1 meter ground apertures are required for near-Earth laser communications. Low-cost ground apertures with equivalent diameters greater than 10 meters are desired for deep-space communications. This presentation focuses on identifying schemes to lower the cost of constructing networks of large apertures while continuing to meet the requirements for laser communications. The primary emphasis here is on the primary mirror. A slumped glass spherical mirror, along with passive secondary mirror corrector and active adaptive optic corrector show promise as a low-cost alternative to large diameter monolithic apertures. To verify the technical performance and cost estimate, development of a 1.5-meter telescope equipped with gimbal and dome is underway.

  18. All-optical OFDM network coding scheme for all-optical virtual private communication in PON

    NASA Astrophysics Data System (ADS)

    Li, Lijun; Gu, Rentao; Ji, Yuefeng; Bai, Lin; Huang, Zhitong

    2014-03-01

    A novel optical orthogonal frequency division multiplexing (OFDM) network coding scheme is proposed over passive optical network (PON) system. The proposed scheme for all-optical virtual private network (VPN) does not only improve transmission efficiency, but also realize full-duplex communication mode in a single fiber. Compared with the traditional all-optical VPN architectures, the all-optical OFDM network coding scheme can support higher speed, more flexible bandwidth allocation, and higher spectrum efficiency. In order to reduce the difficulty of alignment for encoding operation between inter-communication traffic, the width of OFDM subcarrier pulse is stretched in our proposed scheme. The feasibility of all-optical OFDM network coding scheme for VPN is verified, and the relevant simulation results show that the full-duplex inter-communication traffic stream can be transmitted successfully. Furthermore, the tolerance of misalignment existing in inter-ONUs traffic is investigated and analyzed for all-optical encoding operation, and the difficulty of pulse alignment is proved to be lower.

  19. Roadside-based communication system and method

    NASA Technical Reports Server (NTRS)

    Bachelder, Aaron D. (Inventor)

    2007-01-01

    A roadside-based communication system providing backup communication between emergency mobile units and emergency command centers. In the event of failure of a primary communication, the mobile units transmit wireless messages to nearby roadside controllers that may take the form of intersection controllers. The intersection controllers receive the wireless messages, convert the messages into standard digital streams, and transmit the digital streams along a citywide network to a destination intersection or command center.

  20. Optical Communications in Support of Science from the Moon, Mars, and Beyond

    NASA Technical Reports Server (NTRS)

    Edwards, Bernard L.

    2005-01-01

    Optical communications can provide high speed communications throughout the solar system. Enable new science missions and human exploration. The technology suitable for near-earth optical communications, including communications to and from the Moon, is different than for deep space optical. NASA could leverage DoD investments for near-earth applications, including the moon. NASA will have to develop its own technology for deep space. The Mars laser communication demonstration is a pathfinder. NASA,s science mission directorate, under the leadership of Dr. Barry Geldzahler, is developing a roadmap for the development of deep space optical communications.

  1. Link Characterization for Deep-Space Optical Communications

    NASA Astrophysics Data System (ADS)

    Xie, H.; Heckman, D.; Breidenthal, J.

    2016-05-01

    We report the performance of candidate deep-space optical communication systems that would use a single optical ground station in conjunction with various space terminals. We considered three potential diameters of ground receive terminals (4μm, 8μm, and 12μm) and three potential ground transmit powers (1 kW, 5 kW, and 10 kW). Combinations of ground receive terminals, ground transmit terminals, and spacecraft terminals were assessed for data rate and data volume return, both uplink and downlink, and for uplink irradiance needed to enable downlink pointing. System performance was evaluated in the context of a set of 12 design reference missions described in a companion article in this volume. Link performance was evaluated using the Strategic Optical Link Tool, assuming clear weather conditions with conservative desert daytime turbulence. We compared the link performance achievable under our assumptions to the anticipated requirements associated with the design reference missions.

  2. Synchronization using pulsed edge tracking in optical PPM communication system

    NASA Technical Reports Server (NTRS)

    Gagliardi, R.

    1972-01-01

    A pulse position modulated (PPM) optical communication system using narrow pulses of light for data transmission requires accurate time synchronization between transmitter and receiver. The presence of signal energy in the form of optical pulses suggests the use of a pulse edge tracking method of maintaining the necessary timing. The edge tracking operation in a binary PPM system is examined, taking into account the quantum nature of the optical transmissions. Consideration is given first to pure synchronization using a periodic pulsed intensity, then extended to the case where position modulation is present and auxiliary bit decisioning is needed to aid the tracking operation. Performance analysis is made in terms of timing error and its associated statistics. Timing error variances are shown as a function of system signal to noise ratio.

  3. Free-space optical communications link budget estimation.

    PubMed

    Stotts, Larry B; Kolodzy, Paul; Pike, Alan; Graves, Buzz; Dougherty, Dave; Douglass, Jeff

    2010-10-01

    This paper describes a new methodology of estimating free-space optical communications link budgets to be expected in conditions of severe turbulence. The approach is derived from observing that the ability of an adaptive optics (AO) system to compensate turbulence along a path is limited by the transmitter and receiver Rayleigh range, proportional to the diameter of the optics squared and inverse of the wavelength of light utilized. The method uses the Fried parameter computed over the range outside of the transmitter and receiver Rayleigh ranges, to calculate the Strehl ratios that yield a reasonable prediction of the light impinging on the receiving telescope aperture and the power coupling into the fiber. Comparisons will be given between theory and field measurements. These comparisons show that AO is most effective within the Rayleigh ranges, or when an atmospheric gradient is present, and lesser so when the total range is much greater than the sum of the Rayleigh ranges. PMID:20885469

  4. Free space optical communication link using a silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2015-03-01

    Many components for free space optical communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Non-mechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. In this paper a small-scale silicon photonic optical phased array is demonstrated for both the transmitter and receiver functions in a free space optical link. The device using an array of thermo-optically controlled waveguide phase shifters and demonstrates one-dimensional steering with a single control electrode. Transmission of a digitized video data stream over the link is shown.

  5. Multiwavelength optical code-division-multiple-access communication systems

    NASA Astrophysics Data System (ADS)

    Lam, Cedric Fung

    1999-10-01

    There has been tremendous interest in applying spread spectrum and code division multiple access (CDMA) techniques to fiber optic communication systems. In this dissertation, we review the previous work on optical CDMA systems, and we propose and then demonstrate new optical CDMA system designs. The explosive growth in bandwidth demand during the recent years have compelled engineers to achieve one bit per hertz or more bandwidth utilization in optical fibers. We point out that in order to achieve efficient bandwidth utilization, full orthogonality is required in optical CDMA system. At the same time, one would like to avoid having an optical local oscillator, which significantly increases the system complexity. We have studied two spectrally encoded optical CDMA systems, both of which give us full orthogonality. A balanced optical detector, which `computes' the difference between two photodetectors signals, is used to obtain negative outputs from positive-only optical intensity signals, thus achieving full orthogonality in both systems. The first system, complementary spectral intensity encoding, is a fully non-coherent. A novel balanced transmitter has been invented for this system. Unfortunately, the performance of this system is limited by beat noise interference, sometimes called speckle noise. In the second system, spectral phase encoding, a multi-wavelength mode-locked laser source is employed. Spectral phase encoding is applied to various frequency components. By sending the unmodulated carrier along the optical fiber to the receiver, we can achieve the effect of coherent demodulation without using an optical local oscillator. While this system can avoid speckle noise, it is eventually limited by cumulative shot noise. We will show in this dissertation, that cumulative shot noise is unavoidable in all optical CDMA systems. Therefore the ultimate achievable performance of optical CDMA systems under shot noise limitation will be analyzed in this work. Lastly

  6. A graphene-based broadband optical modulator

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Yin, Xiaobo; Ulin-Avila, Erick; Geng, Baisong; Zentgraf, Thomas; Ju, Long; Wang, Feng; Zhang, Xiang

    2011-06-01

    Integrated optical modulators with high modulation speed, small footprint and large optical bandwidth are poised to be the enabling devices for on-chip optical interconnects. Semiconductor modulators have therefore been heavily researched over the past few years. However, the device footprint of silicon-based modulators is of the order of millimetres, owing to its weak electro-optical properties. Germanium and compound semiconductors, on the other hand, face the major challenge of integration with existing silicon electronics and photonics platforms. Integrating silicon modulators with high-quality-factor optical resonators increases the modulation strength, but these devices suffer from intrinsic narrow bandwidth and require sophisticated optical design; they also have stringent fabrication requirements and limited temperature tolerances. Finding a complementary metal-oxide-semiconductor (CMOS)-compatible material with adequate modulation speed and strength has therefore become a task of not only scientific interest, but also industrial importance. Here we experimentally demonstrate a broadband, high-speed, waveguide-integrated electroabsorption modulator based on monolayer graphene. By electrically tuning the Fermi level of the graphene sheet, we demonstrate modulation of the guided light at frequencies over 1GHz, together with a broad operation spectrum that ranges from 1.35 to 1.6µm under ambient conditions. The high modulation efficiency of graphene results in an active device area of merely 25µm2, which is among the smallest to date. This graphene-based optical modulation mechanism, with combined advantages of compact footprint, low operation voltage and ultrafast modulation speed across a broad range of wavelengths, can enable novel architectures for on-chip optical communications.

  7. Power and optical communications for long tie-backs

    NASA Astrophysics Data System (ADS)

    Lecroart, A.; Doyle, L.-P.; Michel, R.; Odier, J.-P.

    2009-04-01

    Large volume neutrino telescopes require real time communications back to shore and a sizeable amount of power at the bottom to feed the detectors and the associated electronics. The telecommunications industry has developed a family of cabled products that have been cost optimized over the years. These submarine cables using optical fibres and a single copper conductor are ideal to achieve the transport of signal and energy. Sea return is required but the overall solution is far less expensive than using a bespoke multi-conductor umbilical design. The quality of neutrino detection may require photo-multipliers to be located in a relatively deep area to limit ambient light noise. This may dictate the choice of the location, which may be tens of kilometres away from the land-based station. If this distance is relatively short then high voltage AC powering can be envisaged. Yet the cable capacitance might become an issue for distances beyond 50 km where the amount of power lost in the cable may become too important. Alcatel-Lucent is developing a 10 kV DC solution based on the advent of a new device converting the 10 kV DC into a more usable 350 or 400 V DC user voltage. Alcatel-Lucent believes that a 10 kV DC solution using Medium Voltage Converters can efficiently bring power to areas located up to 600 km from the shore. In this case, repeaters are used to amplify the light signal along the way. Alcatel-Lucent has qualified repeaters able to sustain a permanent line current of up to 8 A.

  8. Polarization effects in optical fiber communication and distributed vibration sensing systems

    NASA Astrophysics Data System (ADS)

    Zhang, Ziyi

    This thesis includes studies of polarization effects in two main research areas of optical fiber technology: optical fiber communication systems and optical fiber sensors. Polarization of light in optical fiber is sensitive to environmental disturbances. On the negative side, this results in complex measurement processes and errors in communication systems caused by dynamic polarization mode dispersion (PMD) and polarization dependent loss (PDL). On the positive side though, it also results in the possibility of developing a distributed optical fiber vibration sensor. For the purpose of fast polarization measurement for high bit-rate communication systems, a new PDL vector method was proposed based on the equation of motion in Stokes space. It is capable of providing accurate PDL measurements while requiring less measurement steps compared with other available techniques. We had performed a PMD field test, and found the fastest PMD change in submarine fibers under the Caribbean Sea. With long measurement duration (>24h) on one pair of fiber, correlations between polarization effects and tides were reported for the first time. A histogram of the differential group delay (DGD) data and an auto-correlation function of state of polarization (SOP) and DGD were validated by theoretical fittings. The average and fastest drift time for both SOP and DGD was found to be ˜3min and less than 15s, respectively. Polarization effects were then utilized as a sensing parameter to detect and locate external disturbances along the optical fiber. A system based on polarization optical time domain reflectometry (Polarization-OTDR) technique was developed in order to pinpoint the disturbances as well as to give events' frequency information. For the first time, a fully distributed optical fiber vibration sensor has been demonstrated in a 1km fiber link with 10m spatial resolution and 5kHz maximum detectable frequency. Moreover, by our proposed spectrum analysis, multiple simultaneous

  9. Automobile inspection system based on wireless communication

    NASA Astrophysics Data System (ADS)

    Miao, Changyun; Ye, Chunqing

    2010-07-01

    This paper aims to research the Automobile Inspection System based on Wireless Communication, and suggests an overall design scheme which uses GPS for speed detection and Bluetooth and GPRS for communication. The communication between PDA and PC was realized by means of GPRS and TCP/IP; and the hardware circuit and software for detection terminal were devised by means of JINOU-3264 Bluetooth Module after analyzing the Bluetooth and its communication protocol. According to the results of debugging test, this system accomplished GPRS based data communication and management as well as the real-time detection on auto safety performance parameters in crash test via PC, whereby the need for mobility and reliability was met and the efficiency and level of detection was improved.

  10. An ATP System for Deep-Space Optical Communication

    NASA Technical Reports Server (NTRS)

    Lee, Shinhak; Irtuzm Gerardi; Alexander, James

    2008-01-01

    An acquisition, tracking, and pointing (ATP) system is proposed for aiming an optical-communications downlink laser beam from deep space. In providing for a direction reference, the concept exploits the mature technology of star trackers to eliminate the need for a costly and potentially hazardous laser beacon. The system would include one optical and two inertial sensors, each contributing primarily to a different portion of the frequency spectrum of the pointing signal: a star tracker (<10 Hz), a gyroscope (<50 Hz), and a precise fluid-rotor inertial angular-displacement sensor (sometimes called, simply, "angle sensor") for the frequency range >50 Hz. The outputs of these sensors would be combined in an iterative averaging process to obtain high-bandwidth, high-accuracy pointing knowledge. The accuracy of pointing knowledge obtainable by use of the system was estimated on the basis of an 8-cm-diameter telescope and known parameters of commercially available star trackers and inertial sensors: The single-axis pointing-knowledge error was found to be characterized by a standard deviation of 150 nanoradians - below the maximum value (between 200 and 300 nanoradians) likely to be tolerable in deep-space optical communications.

  11. The Impact of Fiber Nonlinearities on Digital Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Chiang, Ting-Kuang

    Wavelength-division multiplexing (WDM) enables high throughput fiber-optic networks by sending several optical channels through a single fiber. Even though the bandwidth of optical fibers is over 25 THz, fiber nonlinearities can limit the capacity of WDM communication systems. Cross -phase modulation (XPM) is one of the nonlinear effects that affect WDM systems. This thesis provides an in-depth understanding of the properties of XPM-induced phase shift and suggests techniques to suppress XPM in long-distance WDM optical networks. In this thesis, XPM is theoretically and experimentally investigated in fiber links with optical amplifiers and dispersion compensators. The theoretical analysis suggests that the XPM effect can be modeled as a phase modulator with inputs from the intensity of co-propagating waves. The frequency response of the phase modulator depends on fiber dispersion, wavelength separation, and fiber length. In non-dispersive fibers, XPM is frequency-independent; in dispersive fibers, the response is approximately inversely proportional to modulation frequency, fiber dispersion, and wavelength separation. In N-segment amplified links with no dispersion compensators, the XPM frequency response is increased N -fold, but only in very narrow frequency bands. In most other frequency bands, the increase is limited and almost independent of N. However, in N-segment amplified links with dispersion compensators, the frequency response of XPM is increased N-fold at all frequencies if the dispersion is compensated for within each fiber segment. The XPM-induced sensitivity penalty in multichannel continuous-phase frequency-shift-keying optical communication systems is investigated by theoretical analysis, computer simulations, and experimental measurements. It is shown that high-frequency components in the XPM-induced phase shift play a more important role in determining the sensitivity penalty than the low-frequency components. The XPM-induced sensitivity penalty

  12. Combining spatial domain multiplexing and orbital angular momentum of photon-based multiplexing to increase the bandwidth of optical fiber communication systems

    NASA Astrophysics Data System (ADS)

    Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Gregory L.; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

    2016-06-01

    Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single-mode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation, five distinct concentric donut-shaped rings with negligible crosstalk at the output end of the fiber were obtained. These SDM channels also exhibit orbital angular momentum (OAM), thereby adding an extradegree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

  13. Gaussian benchmark for optical communication aiming towards ultimate capacity

    NASA Astrophysics Data System (ADS)

    Lee, Jaehak; Ji, Se-Wan; Park, Jiyong; Nha, Hyunchul

    2016-05-01

    We establish the fundamental limit of communication capacity within Gaussian schemes under phase-insensitive Gaussian channels, which employ multimode Gaussian states for encoding and collective Gaussian operations and measurements for decoding. We prove that this Gaussian capacity is additive, i.e., its upper bound occurs with separable encoding and separable receivers so that a single-mode communication suffices to achieve the largest capacity under Gaussian schemes. This rigorously characterizes the gap between the ultimate Holevo capacity and the capacity within Gaussian communication, showing that Gaussian regime is not sufficient to achieve the Holevo bound particularly in the low-photon regime. Furthermore, the Gaussian benchmark established here can be used to critically assess the performance of non-Gaussian protocols for optical communication. We move on to identify non-Gaussian schemes to beat the Gaussian capacity and show that a non-Gaussian receiver recently implemented by Becerra et al. [F. E. Becerra et al., Nat. Photon. 7, 147 (2013), 10.1038/nphoton.2012.316] can achieve this aim with an appropriately chosen encoding strategy.

  14. Non-line-of-sight underwater optical wireless communication network.

    PubMed

    Arnon, Shlomi; Kedar, Debbie

    2009-03-01

    The growing need for ocean observation systems has stimulated considerable interest within the research community in advancing the enabling technologies of underwater wireless communication and underwater sensor networks. Sensors and ad hoc sensor networks are the emerging tools for performing extensive data-gathering operations on land, and solutions in the subsea setting are being sought. Efficient communication from the sensors and within the network is critical, but the underwater environment is extremely challenging. Addressing the special features of underwater wireless communication in sensor networks, we propose a novel non-line-of-sight network concept in which the link is implemented by means of back-reflection of the propagating optic signal at the ocean-air interface and derive a mathematical model of the channel. Point-to-multipoint links can be achieved in an energy efficient manner and broadcast broadband communications, such as video transmissions, can be executed. We show achievable bit error rates as a function of sensor node separation and demonstrate the feasibility of this concept using state-of-the-art silicon photomultiplier detectors. PMID:19252651

  15. LLCD operations using the Optical Communications Telescope Laboratory (OCTL)

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Kovalik, Joseph M.; Wright, Malcolm W.; Roberts, William T.; Cheng, Michael K.; Quirk, Kevin J.; Srinivasan, Meera; Shaw, Matthew D.; Birnbaum, Kevin M.

    2014-03-01

    The Optical Communications Telescope Laboratory (OCTL) located on Table Mountain near Wrightwood, CA served as an alternate ground terminal to the Lunar Laser Communications Demonstration (LLCD), the first free-space laser communication demonstration from lunar distances. The Lunar Lasercom OCTL Terminal (LLOT) Project utilized the existing 1m diameter OCTL telescope by retrofitting: (i) a multi-beam 1568 nm laser beacon transmitter; (ii) a tungsten silicide (WSi) superconducting nanowire single photon detector (SNSPD) receiver for 1550 nm downlink; (iii) a telescope control system with the functionality required for laser communication operations; and (iv) a secure network connection to the Lunar Lasercom Operations Center (LLOC) located at the Lincoln Laboratory, Massachusetts Institute of Technology (LL-MIT). The laser beacon transmitted from Table Mountain was acquired by the Lunar Lasercom Space Terminal (LLST) on-board the Lunar Atmospheric Dust Environment Explorer (LADEE) spacecraft and a 1550 nm downlink at 39 and 78 Mb/s was returned to LLOT. Link operations were coordinated by LLOC. During October and November of 2013, twenty successful links were accomplished under diverse conditions. In this paper, a brief system level description of LLOT along with the concept of operations and selected results are presented.

  16. Free-space optical communication systems (FOCUS): a U.S. Army overview

    NASA Astrophysics Data System (ADS)

    Vallestero, Neil J.; Khusid, Mark; Prasad, Narasimha S.; Carrano, John C.; Duchak, George; Ricklin, Jennifer C.; Vorontsov, Mikhail A.

    2002-12-01

    The Army's objective is to design, develop and demonstrate its 'ability to distribute information around the battlefield.' Future Army systems will be based on a survivable, adaptable network capable of integrating commercial services and securely utilizing bandwidth for voice, data, and video applications. However, microwave bandwidth allocation has been a serious problem (given crosstalk, interference and frequency management) for a mobile, adaptive communication network. Because of the inherent advantages of the high data rate, crosstalk independence, jam - resistance, covertness and quick system setup time, the Army is looking into optical wireless communication as a means to address this communications requirement. However, development of a fielded laser communication system requires the development of enabling technologies, the understanding of physical limits and performance, and concept of operations (CONOPS).

  17. Optical wireless communication in sensor networks: data harvesting for disaster recovery operations

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi; Kedar, Debbie

    2007-09-01

    Networks of sensors are an emerging technology for real-time data gathering in applications such as pollution monitoring, home security, surveillance, industrial control, etc. Many miniature nodes with sensing, computing and wireless communication capabilities are randomly deployed in an area or volume to be probed. One of the possible communication modalities for sensor networks is optical wireless communication (OWC). Initially, the sensor population must be mapped prior to interrogation by the base station and data communication from the sensor node. In this paper we review some theoretical and experimental work in this area and underline some of the challenges and possible solutions. The specific scenario of wireless sensor networks in a disaster recovery operation is modeled.

  18. Some Protocols For Optical-Fiber Digital Communications

    NASA Technical Reports Server (NTRS)

    Yeh, Cavour; Gerla, Mario

    1989-01-01

    One works best in heavy traffic, another, in light traffic. Three protocols proposed for digital communications among stations connected by passive taps to pair of uni-directional optical-fiber buses. Mediate round-robin, bounded-delay access to buses by all stations and particularly suited to fast transmission. Partly because transmission medium passive (no relay stations) and partly because protocols distribute control of network among all stations with provision for addition and deletion of stations (no control stations), communication network able to resist and recover from failures. Implicit token propagates in one direction on one bus and in opposite direction on other bus, minimizing interval of silence between end of one round and beginning of next.

  19. Underwater optical wireless communications: depth-dependent beam refraction.

    PubMed

    Johnson, Laura J; Green, Roger J; Leeson, Mark S

    2014-11-01

    Global refractive gradients in seawater cause pointing problems for optical wireless communications. A refractive index depth profile of the Pacific Ocean was calculated from measured salinity, temperature, and pressure, determining the end points of a refracted and nonrefracted 200 m communication link. Numerical ray tracing was used with a point source for angles between 10° and 80° and transmission wavelengths of 500-650 nm; the maximum end-point difference found was 0.23 m. A 500 nm laser with a 0.57° full-angle FOV was traced; the nonrefracted receiver location was outside the FOV for all links angled >15° to the vertical. However, most pointing issues underwater are unlikely to be significant with suitable FOV choice and natural scattering of the source. PMID:25402887

  20. Options for daytime monitoring of atmospheric visibility in optical communications

    NASA Technical Reports Server (NTRS)

    Erickson, D.; Cowles, K.

    1989-01-01

    Techniques for daytime detection of atmospheric transmission and cloud cover to determine the capabilities of future deep-space optical communications links are considered. A modification of the planned nighttime photometry program will provide the best data while minimizing the need for further equipment. Greater degrees of modification will provide increased detection capabilities. Future testing of the equipment will better define the improvement offered by each level of modification. Daytime photometry is favored at certain wavelengths because of higher transmission and lower background noise, thus giving an increased signal-to-noise ratio. A literature search has provided a list of stars brighter than second magnitude at these wavelengths.

  1. Performance of PLL synchronized optical PPM communication systems

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.; Gardner, C. S.

    1986-01-01

    Receiver timing synchronization of an optical PPM communication system can be achieved using a phase-locked loop (PLL) if the photodetector output is properly processed. The synchronization performance is shown to improve with increasing signal power and decreasing loop bandwidth. The bit error rate performance of the PLL synchronized PPM system is analyzed and compared to that of the perfectly synchronized system. It is shown that the increase in signal power needed to compensate for the imperfect sychronization is small (less than 0.1 dB) for loop bandwidths less than 0.1 percent of the slot frequency.

  2. PAPR reduction techniques for asymmetrically clipped optical OFDM communication system

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Zhang, Zhaojun; Sun, Lu

    2014-07-01

    In the ultraviolet communication system, ACO-OFDM technology can effectively suppress inter-symbol interference on the system performance, and further improve the transmission rate of the system. However, ACO-OFDM has a high peak to average power ratio (PAPR), and high PAPR not only reduces the power efficiency of the optical modulator, but also bring damage to the human eye or skin. In order to solve the above problem, according to ACO-OFDM signal characteristics, two clipping and filtering algorithms are used, and its performance is simulated, the simulations show that the two algorithms are able to inhibit well the PAPR of ACO-OFDM system.

  3. Calculations of laser cavity dumping for optical communications

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Rayman, M. D.

    1988-01-01

    For deep-space pulse-position modulation (PPM) optical communication links using Nd:YAG lasers, two types of laser transmitter modulation techniques are available for efficiently producing laser pulses over a broad range of repetition rates: Q-switching and cavity dumping. The desired modulation scheme is dependent on the required pulse repetition frequency and link parameters. These two techniques are discussed, theoretical and numerical calculations of the internal energy of the laser cavity in cavity dumping are described, and an example of cavity dumping is applied to a link for a proposed experiment package on Cassini.

  4. Word and frame synchronization with verification for PPM optical communications

    NASA Technical Reports Server (NTRS)

    Marshall, William K.

    1986-01-01

    A method for obtaining word and frame synchronization in pulse position modulated optical communication systems is described. The method uses a short sync sequence inserted at the beginning of each data frame and a verification procedure to distinguish between inserted and randomly occurring sequences at the receiver. This results in an easy to implement sync system which provides reliable synchronization even at high symbol error rates. Results are given for the application of this approach to a highly energy efficient 256-ary PPM test system.

  5. Numerical modelling of multimode fibre-optic communication lines

    NASA Astrophysics Data System (ADS)

    Sidelnikov, O. S.; Sygletos, S.; Ferreira, F.; Fedoruk, M. P.

    2016-01-01

    The results of numerical modelling of nonlinear propagation of an optical signal in multimode fibres with a small differential group delay are presented. It is found that the dependence of the error vector magnitude (EVM) on the differential group delay can be reduced by increasing the number of ADC samples per symbol in the numerical implementation of the differential group delay compensation algorithm in the receiver. The possibility of using multimode fibres with a small differential group delay for data transmission in modern digital communication systems is demonstrated. It is shown that with increasing number of modes the strong coupling regime provides a lower EVM level than the weak coupling one.

  6. Laser Communications and Fiber Optics Lab Manual. High-Technology Training Module.

    ERIC Educational Resources Information Center

    Biddick, Robert

    This laboratory training manual on laser communications and fiber optics may be used in a general technology-communications course for ninth graders. Upon completion of this exercise, students achieve the following goals: match concepts with laser communication system parts; explain advantages of fiber optic cable over conventional copper wire;…

  7. Non-Mechanical Beam Steering in Free-Space Optical Communication Transceivers

    NASA Astrophysics Data System (ADS)

    Shortt, Kevin

    Free-space optical communications systems are a rapidly growing field as they carry many of the advantages of traditional fibre-based communications systems without the added investment of installing complex infrastructure. Moreover, these systems are finding key niches in mobile platforms in order to take advantage of the increased bandwidth over traditional RF systems. Of course, the inevitable problem of tracking arises when dealing with mobile stations. To compound the problem in the case of communications to low Earth or geosynchronous orbits, FSOC systems typically operate with tightly confined beams over great distances often requiring pointing accuracies on the order of micro-radians or smaller. Mechanisms such as gimbal mounts and fine-steering mirrors are the usual candidates for platform stabilization, however, these clearly have substantial power requirements and inflate the mass of the system. Spatial light modulators (also known as optical phased arrays), on the other hand, offer a suitable alternative for beam-pointing stabilization. Some of the advantages of spatial light modulators over fine-steering mirrors include programmable multiple simultaneous beams, dynamic focus/defocus and moderate to excellent optical power handling capability. This thesis serves as an investigation into the implementation of spatial light modulators as a replacement for traditional fine-steering mirrors in the fine-pointing subsystem. In particular, pointing accuracy and scanning ability will be highlighted as performance metrics in the context of a variety of communication scenarios. Keywords: Free-space optical communications, beam steering, fine-steering mirror, spatial light modulator, optical phased array.

  8. LEO to ground optical communications from a small satellite platform

    NASA Astrophysics Data System (ADS)

    Rose, T. S.; Janson, S. W.; LaLumondiere, S.; Werner, N.; Hinkley, D. H.; Rowen, D. W.; Fields, R. A.; Welle, R. P.

    2015-03-01

    A pair of 2.2 kg CubeSats using COTS hardware is being developed for a proof-of-principle optical communications demo from a 450-600 km LEO orbit to ground. The 10x10x15 cm platform incorporates a 25% wall-plug efficient 10-W Yb fiber transmitter emitting at 1.06 μm. Since there are no gimbals on board, the entire spacecraft is body-steered toward the ground station. The pointing accuracy of the LEO craft, which governs the data rate capability, is expected to be ~ 0.1-0.2 deg. Two optical ground stations, located at the Mt. Wilson observatory, have receiver apertures of 30 and 80 cm. Launch of the CubeSat pair is anticipated to be mid to late 2015.

  9. Advanced Approach of Multiagent Based Buoy Communication

    PubMed Central

    Gricius, Gediminas; Drungilas, Darius; Andziulis, Arunas; Dzemydiene, Dale; Voznak, Miroslav; Kurmis, Mindaugas; Jakovlev, Sergej

    2015-01-01

    Usually, a hydrometeorological information system is faced with great data flows, but the data levels are often excessive, depending on the observed region of the water. The paper presents advanced buoy communication technologies based on multiagent interaction and data exchange between several monitoring system nodes. The proposed management of buoy communication is based on a clustering algorithm, which enables the performance of the hydrometeorological information system to be enhanced. The experiment is based on the design and analysis of the inexpensive but reliable Baltic Sea autonomous monitoring network (buoys), which would be able to continuously monitor and collect temperature, waviness, and other required data. The proposed approach of multiagent based buoy communication enables all the data from the costal-based station to be monitored with limited transition speed by setting different tasks for the agent-based buoy system according to the clustering information. PMID:26345197

  10. Advanced Approach of Multiagent Based Buoy Communication.

    PubMed

    Gricius, Gediminas; Drungilas, Darius; Andziulis, Arunas; Dzemydiene, Dale; Voznak, Miroslav; Kurmis, Mindaugas; Jakovlev, Sergej

    2015-01-01

    Usually, a hydrometeorological information system is faced with great data flows, but the data levels are often excessive, depending on the observed region of the water. The paper presents advanced buoy communication technologies based on multiagent interaction and data exchange between several monitoring system nodes. The proposed management of buoy communication is based on a clustering algorithm, which enables the performance of the hydrometeorological information system to be enhanced. The experiment is based on the design and analysis of the inexpensive but reliable Baltic Sea autonomous monitoring network (buoys), which would be able to continuously monitor and collect temperature, waviness, and other required data. The proposed approach of multiagent based buoy communication enables all the data from the costal-based station to be monitored with limited transition speed by setting different tasks for the agent-based buoy system according to the clustering information. PMID:26345197

  11. Optical backpropagation for fiber-optic communications using optical phase conjugation at the receiver.

    PubMed

    Shao, Jing; Kumar, Shiva

    2012-08-01

    A fiber-optic system design with optical backpropagation that uses an optical phase conjugator, high-dispersion fibers, and highly nonlinear fibers is investigated. The proposed technique outperforms the midpoint optical phase conjugation and digital backpropagation with the same step size. PMID:22859069

  12. Optimum LED wavelength for underwater optical wireless communication at turbid water

    NASA Astrophysics Data System (ADS)

    Rosenkrantz, Etai; Arnon, Shlomi

    2014-10-01

    Underwater optical wireless communication is an emerging technology, which can provide high data rate. High data rate communication is required for applications such as underwater imaging, networks of sensors and swarms of underwater vehicles. These applications pursue an affordable light source, which can be obtained by light emitting diodes (LED). LEDs offer solutions characterized by low cost, high efficiency, reliability and compactness based on off-the-shelf components such as blue and green light emitting diodes. In this paper we present our recent theoretical and experimental results in this field.

  13. Airborne Optical Communications Demonstrator Design And Preflight Test Results

    NASA Technical Reports Server (NTRS)

    Biswas, Abhijit; Page, N.; Neal, J.; Zhu, D.; Wright, M.; Ovtiz, G.; Farr, W. H.; Hernnzati, H.

    2005-01-01

    A second generation optical communications demonstrator (OCD-2) intended for airborne applications like air-to-ground and air-to-air optical links is under development at JPL. This development provides the capability for unidirectional high data rate (2.5-Gbps) transmission at 1550-nm, with the ability to receive an 810-nm beacon to aid acquisition pointing and tracking. The transmitted beam width is nominally 200-(micro)rad. A 3x3 degree coarse field-of-view (FOV) acquisition sensor with a much smaller 3-mrad FOV tracking sensor is incorporated. The OCD-2 optical head will be integrated to a high performance gimbal turret assembly capable of providing pointing stability of 5- microradians from an airborne platform. Other parts of OCD-2 include a cable harness, connecting the optical head in the gimbal turret assembly to a rugged electronics box. The electronics box will house: command and control processors, laser transmitter, data-generation-electronics, power conversion/distribution hardware and state-of-health monitors. The entire assembly will be integrated and laboratory tested prior to a planned flight demonstrations.

  14. Optical Receiver Based On Luminescent Light Trapping

    NASA Technical Reports Server (NTRS)

    Perry, Joseph W.; Cole, Terry; Zewail, Ahmed H.

    1991-01-01

    Experiment demonstrates feasibility of optical-communication receiver based on luminescent light trapping. Light-gathering element plate of transparent material impregnated with laser dye. Light from distant laser transmitter falls on plate and absorbed by dye molecules, which become excited and reradiate. Reradiated light confined within plate by total internal reflection as it propagates toward edge of plate. Light arriving at edge escapes from plate and detected by small, high-speed, high-gain photomultiplier tubes or other photosensitive devices. Simple, inexpensive, and accepts light from almost any angle. Receiver of this configuration supports reception of data at rate of 13 MHz and higher.

  15. The study of optical fiber communication technology for space optical remote sensing

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Yu, Sheng-quan; Zhang, Xiao-hong; Zhang, Rong-hui; Ma, Jian-hua

    2012-11-01

    The latest trends of Space Optical Remote Sensing are high-resolution, multispectral, and wide swath detecting. High-speed digital image data transmission will be more important for remote sensing. At present, the data output interface of Space Optical Remote Sensing, after performing the image data compression and formatting, transfers the image data to data storage unit of the Spacecraft through LVDS circuit cables. But this method is not recommended for high-speed digital image data transmission. This type of image data transmission, called source synchronization, has the low performance for high-speed digital signal. Besides, it is difficult for cable installing and system testing in limited space of vehicle. To resolve these issues as above, this paper describes a high-speed interconnection device for Space Optical Remote Sensing with Spacecraft. To meet its objectives, this device is comprised of Virtex-5 FPGA with embedded high-speed series and power-efficient transceiver, fiber-optic transceiver module, the unit of fiber-optic connection and single mode optical fiber. The special communication protocol is performed for image data transferring system. The unit of fiber-optic connection with high reliability and flexibility is provided for transferring high-speed serial data with optical fiber. It is evident that this method provides many advantages for Space Optical Remote Sensing: 1. Improving the speed of image data transferring of Space Optical Remote Sensing; 2. Enhancing the reliability and safety of image data transferring; 3. Space Optical Remote Sensing will be reduced significantly in size and in weight; 4. System installing and system testing for Space Optical Remote Sensing will become easier.

  16. Automated alignment system for optical wireless communication systems using image recognition.

    PubMed

    Brandl, Paul; Weiss, Alexander; Zimmermann, Horst

    2014-07-01

    In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receiver's position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10⁻⁹) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s. PMID:24978803

  17. X-ray communication based simultaneous communication and ranging

    NASA Astrophysics Data System (ADS)

    Song, Shi-Bin; Xu, Lu-Ping; Zhang, Hua; Gao, Na

    2015-09-01

    To improve the link efficiency and decrease the payloads in space explorations, a novel simultaneous communication and ranging method based on x-ray communication (XCOM) is proposed in this paper. A delicate signal symbol structure is utilized to achieve simultaneous data transmission and range measurement. With the designed symbol structure, the ranging information is imbedded into the communication signal and transmitted with it simultaneously. The range measurement is realized by the two-way transmission of the range information. To illustrate the proposed method, firstly, the principle of the method is introduced and the signal processing procedure is presented. Then, the performance of the proposed method is analyzed theoretically in various aspects, including the acquisition probability, the bit error rate, the ranging jitter, etc. Besides, numerical experiments are conducted to verify the proposed method and evaluate the system performance. The simulation results show that the proposed method is feasible and that the system performance is influenced by the parameters concerning the signal symbol structure. Compared with the previous methods, the proposed method improves the link efficiency and is beneficial for system miniaturization and integration, which could provide a potential option for future deep space explorations. Project supported by the National Natural Science Foundation of China (Grant Nos. 61172138 and 61401340), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20130203120004), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 201413B, 201412B, and JB141303).

  18. Coherent Terahertz Wireless Signal Transmission Using Advanced Optical Fiber Communication Technology

    NASA Astrophysics Data System (ADS)

    Kanno, Atsushi; Kuri, Toshiaki; Morohashi, Isao; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Kitayama, Ken-ichi

    2015-02-01

    Coherent terahertz signal transmission with multilevel modulation and demodulation is demonstrated using an optical sub-harmonic IQ mixer (SHIQM), which consists of optical components in advanced optical fiber communication technologies. An optical-frequency-comb-employed signal generator is capable of vector modulation as well as frequency tunability. Digital signal processing (DSP) adopted from the recently developed optical digital coherent communication can easily demodulate multi-level modulated terahertz signals by using electrical heterodyning for intermediate-frequency (IF) down conversion. This technique is applicable for mobile backhauling in the next-generation mobile communication technology directly connected to an optical fiber network as a high-speed wireless transmission link.

  19. Free-space optical communication through a forest canopy

    NASA Astrophysics Data System (ADS)

    Edwards, Clinton L.; Davis, Christopher C.

    2006-01-01

    We model the effects of the leaves of mature broadleaf (deciduous) trees on air-to-ground free-space optical communication systems operating through the leaf canopy. The concept of leaf area index (LAI) is reviewed and related to a probabilistic model of foliage consisting of obscuring leaves randomly distributed throughout a treetop layer. Individual leaves are opaque. The expected fractional unobscured area statistic is derived as well as the variance around the expected value. Monte Carlo simulation results confirm the predictions of this probabilistic model. To verify the predictions of the statistical model experimentally, a passive optical technique has been used to make measurements of observed sky illumination in a mature broadleaf environment. The results of the measurements, as a function of zenith angle, provide strong evidence for the applicability of the model, and a single parameter fit to the data reinforces a natural connection to LAI. Specific simulations of signal-to-noise ratio degradation as a function of zenith angle in a specific ground-to-unmanned aerial vehicle communication situation have demonstrated the effect of obscuration on performance.

  20. Free-space optical communication through a forest canopy.

    PubMed

    Edwards, Clinton L; Davis, Christopher C

    2006-01-01

    We model the effects of the leaves of mature broadleaf (deciduous) trees on air-to-ground free-space optical communication systems operating through the leaf canopy. The concept of leaf area index (LAI) is reviewed and related to a probabilistic model of foliage consisting of obscuring leaves randomly distributed throughout a treetop layer. Individual leaves are opaque. The expected fractional unobscured area statistic is derived as well as the variance around the expected value. Monte Carlo simulation results confirm the predictions of this probabilistic model. To verify the predictions of the statistical model experimentally, a passive optical technique has been used to make measurements of observed sky illumination in a mature broadleaf environment. The results of the measurements, as a function of zenith angle, provide strong evidence for the applicability of the model, and a single parameter fit to the data reinforces a natural connection to LAI. Specific simulations of signal-to-noise ratio degradation as a function of zenith angle in a specific ground-to-unmanned aerial vehicle communication situation have demonstrated the effect of obscuration on performance. PMID:16422338

  1. Robust Short-Pulse, High-Peak-Power Laser Transmitter for Optical Communications

    NASA Technical Reports Server (NTRS)

    Wright, Malcolm W.

    2009-01-01

    We report on a pulsed fiber based master oscillator power amplifier laser at 1550 nm to support moderate data rates with high peak powers in a compact package suitable for interplanetary optical communications. To accommodate pulse position modulation, the polarization maintaining laser transmitter generates pulses from 0.1 to 1 ns with variable duty cycle over a pulse repetition frequency range of 10 to 100 MHz.

  2. Optical chaos synchronization and encrypted communications of VCSEL by direct optical injection

    NASA Astrophysics Data System (ADS)

    Hosomi, Naohito; Sasaki, Wakao

    2014-09-01

    In this work, we propose electro-optical nonlinear delayed feedback systems (NDFS) for optical secure communications using VCSEL for the first time. Its optical output can perform more sensitive chaotic dynamics by varying only a few mA of injection current range resulting in very significant charges of VCSEL's operation conditions from threshold to maximum rating. This enables us to vary chaotic output dynamically by a slight difference of initial values in NDFS. We have proposed a chaos synchronization system using two identical NDFS's of VCSEL, and realized chaos synchronization by optical injection. As a result of experiment the correlation coefficient up to about 0.88 was obtained. Moreover, by varying the delay time and feedback gain in the parameters of NDFSs, we have confirmed that the variations of these parameters may affect variations of correlation.

  3. Antenna gain of actively compensated free-space optical communication systems under strong turbulence conditions.

    PubMed

    Juarez, Juan C; Brown, David M; Young, David W

    2014-05-19

    Current Strehl ratio models for actively compensated free-space optical communications terminals do not accurately predict system performance under strong turbulence conditions as they are based on weak turbulence theory. For evaluation of compensated systems, we present an approach for simulating the Strehl ratio with both low-order (tip/tilt) and higher-order (adaptive optics) correction. Our simulation results are then compared to the published models and their range of turbulence validity is assessed. Finally, we propose a new Strehl ratio model and antenna gain equation that are valid for general turbulence conditions independent of the degree of compensation. PMID:24921373

  4. Space-Based Erbium-Doped Fiber Amplifier Transmitters for Coherent, Ranging, 3D-Imaging, Altimetry, Topology, and Carbon Dioxide Lidar and Earth and Planetary Optical Laser Communications

    NASA Astrophysics Data System (ADS)

    Storm, Mark; Engin, Doruk; Mathason, Brian; Utano, Rich; Gupta, Shantanu

    2016-06-01

    This paper describes Fibertek, Inc.'s progress in developing space-qualified Erbium-doped fiber amplifier (EDFA) transmitters for laser communications and ranging/topology, and CO2 integrated path differential absorption (IPDA) lidar. High peak power (1 kW) and 6 W of average power supporting multiple communications formats has been demonstrated with 17% efficiency in a compact 3 kg package. The unit has been tested to Technology Readiness Level (TRL) 6 standards. A 20 W EDFA suitable for CO2 lidar has been demonstrated with ~14% efficiency (electrical to optical [e-o]) and its performance optimized for 1571 nm operation.

  5. Improved coded optical communication error rates using joint detection receivers

    NASA Astrophysics Data System (ADS)

    Dutton, Zachary; Guha, Saikat; Chen, Jian; Habif, Jonathan; Lazarus, Richard

    2012-02-01

    It is now known that coherent state (laser light) modulation is sufficient to reach the ultimate quantum limit (the Holevo bound) for classical communication capacity. However, all current optical communication systems are fundamentally limited in capacity because they perform measurements on single symbols at a time. To reach the Holevo bound, joint quantum measurements over long symbol blocks will be required. We recently proposed and demonstrated the ``conditional pulse nulling'' (CPN) receiver -- which acts jointly on the time slots of a pulse-position-modulation (PPM) codeword by employing pulse nulling and quantum feedforward -- and demonstrated a 2.3 dB improvement in error rate over direct detection (DD). In a communication system coded error rates are made arbitrary small by employing an outer code (such as Reed-Solomon (RS)). Here we analyze RS coding of PPM errors with both DD and CPN receivers and calculate the outer code length requirements. We find the improved PPM error rates with the CPN translates into >10 times improvement in the required outer code length at high rates. This advantage also translates increase the range for a given coding complexity. In addition, we present results for outer coded error rates of our recently proposed ``Green Machine'' which realizes a joint detection advantage for binary phase shift keyed (BPSK) modulation.

  6. Electro-Optical Design for Efficient Visual Communication

    NASA Technical Reports Server (NTRS)

    Huck, Friedrich O.; Fales, Carl L.; Jobson, Daniel J.; Rahman, Zia-Ur

    1995-01-01

    Visual communication, in the form of telephotography and television, for example, can be regarded as efficient only if the amount of information that it conveys about the scene to the observer approaches the maximum possible and the associated cost approaches the minimum possible. Elsewhere we have addressed the problem of assessing the end to end performance of visual communication systems in terms of their efficiency in this sense by integrating the critical limiting factors that constrain image gathering into classical communications theory. We use this approach to assess the electro-optical design of image gathering devices as a function of the f number and apodization of the objective lens and the aperture size and sampling geometry of the phot-detection mechanism. Results show that an image gathering device that is designed to optimize information capacity performs similarly to the human eye. For both, the performance approaches the maximum possible, in terms of the efficiency with which the acquired information can be transmitted as decorrelated data, and the fidelity, sharpness, and clearity with which fine detail can be restored.

  7. HgCdTe APDs for free space optical communications

    NASA Astrophysics Data System (ADS)

    Rothman, J.; Lasfargues, G.; Abergel, J.

    2015-10-01

    HgCdTe avalanche photodiode single element detectors have been developed for a large scope of photon starved applications. The present communication is dedicated to use of these detectors for free space optical communications. In this perspective we present and discuss the sensitivity and bandwidth that has been measured directly on HgCdTe APDs and on detector modules. In particular, we report on the performance of TEC cooled large area detectors with sensitive diameters ranging from 30- 200 μm, characterised by detector gains of 2- 20 V/μW and noise equivalent input power of 0.1-1 nW for bandwidths ranging from 20 to 400 MHz. One of these detectors has been used during the lunar laser communication demonstration (LLCD) and the results The perspectives for high data rate transmission is estimated from the results of impulse response measurements on HgCdTe APDs. These results indicate that bandwidths close to 10 GHz can be achieved in these devices. The associated sensitivity at an APD gain of 100 is estimated to be below 4 photons rms (NEP<10 nW) for APDs operated at 300 K.

  8. Receiver front end for optical free space communications

    NASA Astrophysics Data System (ADS)

    Hildebrand, Ulrich

    1994-09-01

    The Receiver Front End (RFE) is the optical receiver of ESA's Semiconductor Laser Intersatellite Link Experiment (SILEX). Optical free space communication between satellites is characterized by narrow beams and therefore by demanding requirements for pointing accuracy. This applies for the steering of the laser beam in transmission, for the pointing of the receiver's field of view (FOV), and for the alignment between transmitted and received beams. The RFE housing, the optical system, the lens and detector's mounting have to be designed to meet the stringent requirements for angular stability. This paper concentrates on the mechanical and thermal aspects which strongly influence the performance. Thermal expansion effects are of major concern when keeping the optical axis stable. All materials have been matched to the thermal expansion characteristics of the hybrid circuit which contains the detector. Assuming only homogeneous temperature changes during life, no stress or angular deviations have to be expected. The relative changes of dimensions in any direction stays equal at different temperatures. The verification of opto-mechanical performance requires sophisticated measurement tools. Measurements have to be performed in order to determine the lateral stability of lens and detector. A dedicated autocollimator was developed which measures the angular stability of the optical axis after vibration, thermo-vacuum test and under temperature changes. It also serves as a test transmitter. Measurement accuracies of 5 (mu) rad have been achieved. For the measurements the RFE is mounted onto a test fixture. A reference mirror on the fixture is the stable reference which has to be more stable than the equipment itself.

  9. Free-space laser communication system with rapid acquisition based on astronomical telescopes.

    PubMed

    Wang, Jianmin; Lv, Junyi; Zhao, Guang; Wang, Gang

    2015-08-10

    The general structure of a free-space optical (FSO) communication system based on astronomical telescopes is proposed. The light path for astronomical observation and for communication can be easily switched. A separate camera is used as a star sensor to determine the pointing direction of the optical terminal's antenna. The new system exhibits rapid acquisition and is widely applicable in various astronomical telescope systems and wavelengths. We present a detailed analysis of the acquisition time, which can be decreased by one order of magnitude compared with traditional optical communication systems. Furthermore, we verify software algorithms and tracking accuracy. PMID:26367918

  10. Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

    NASA Astrophysics Data System (ADS)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

    2016-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

  11. Communication Technologies Preferred by School Based Administrators

    ERIC Educational Resources Information Center

    Weir, Paul

    2012-01-01

    The purpose of this study was to determine the communication technologies preferred by school based administrators. This study surveyed and interviewed 96 school based administrators in a mid-sized suburban school system. The data show that individual emails, email lists, and cell phone technologies had the highest percentage effectiveness ratings…

  12. Thin film technologies for optoelectronic components in fiber optic communication

    NASA Astrophysics Data System (ADS)

    Perinati, Agostino

    1998-02-01

    'The Asian Routes Towards the Global Information Society' and 'Towards a Strategic Planning for the Global Information Society' will be the forum themes of 'Asia Telecom 97' and 'Telecom Interactice 97' events respectively, to be held by the International Telecommunication Union (ITU) in order to further telecommunication development around the world. International telecommunications network affects our life by keeping us in touch, bringing us world news and underpinning the global economy. Global tele-economy, global information infrastructure, global information society terms are more and more used to indicate the evolution towards an information- driven world where the access to information, communication and technologies is essential to the economic and social development in every country. Telecommunication industry can strongly contribute to this evolution together with broadcasting and computer industry, and fiber optic communications are expected to continue to grow up and share a relevant part of the total telecom market. In 1995 telecom market shown a 3.8 percent worldwide investment growth reaching a 545 billion value. According to 'Kessler Marketing Intelligence (KMI) Corp.' analysis of fiberoptics and multimedia market the amount of cabled fiber installed in U.S. will be around 11 million fiber-km in 1997 and 15 million fiber-km are predicted in the year 2000. Between 1995 and 1998 the undersea industry is estimated to deal with 13.9 billion as additional undersea cable systems investment in the global telecom network. In China beside satellite telecom stations and digital microwave systems 22 fiber optic backbones have been realized and another 23 systems are expected to be built in the Ninth Five-Year National Plan (1996 to approximately 2000) with a total length of nearly 30,000 sheat-km. The study, Fiber and Fiberoptic Cable Markets in China, recently released by KMI Corp. shows that fiber optic cable installation by MPT and other network operators

  13. Optical Phase Recovery and Locking in a PPM Laser Communication Link

    NASA Technical Reports Server (NTRS)

    Aveline, David C.; Yu, Nan; Farr, William H.

    2012-01-01

    Free-space optical communication holds great promise for future space missions requiring high data rates. For data communication in deep space, the current architecture employs pulse position modulation (PPM). In this scheme, the light is transmitted and detected as pulses within an array of time slots. While the PPM method is efficient for data transmission, the phase of the laser light is not utilized. The phase coherence of a PPM optical signal has been investigated with the goal of developing a new laser communication and ranging scheme that utilizes optical coherence within the established PPM architecture and photon-counting detection (PCD). Experimental measurements of a PPM modulated optical signal were conducted, and modeling code was developed to generate random PPM signals and simulate spectra via FFT (Fast Fourier Transform) analysis. The experimental results show very good agreement with the simulations and confirm that coherence is preserved despite modulation with high extinction ratios and very low duty cycles. A real-time technique has been developed to recover the phase information through the mixing of a PPM signal with a frequency-shifted local oscillator (LO). This mixed signal is amplified, filtered, and integrated to generate a voltage proportional to the phase of the modulated signal. By choosing an appropriate time constant for integration, one can maintain a phase lock despite long dark times between consecutive pulses with low duty cycle. A proof-of-principle demonstration was first achieved with an RF-based PPM signal and test setup. With the same principle method, an optical carrier within a PPM modulated laser beam could also be tracked and recovered. A reference laser was phase-locked to an independent pulsed laser signal with low-duty-cycle pseudo-random PPM codes. In this way, the drifting carrier frequency in the primary laser source is tracked via its phase change in the mixed beat note, while the corresponding voltage feedback

  14. Optical switch based on nanocrystalline VOx thin film

    NASA Astrophysics Data System (ADS)

    Chen, Xiqu; Dai, Jun

    2009-11-01

    An optical switch is fabricated based on nanocrystalline vanadium oxide (VOx) thin film using micromachining technology. An "on" state with semiconducting phase to an "off" state with metallic phase is controlled by applying a DC power to Aurum electrodes of the optical switch. The optical switching performance for the fabricated device is investigated at optical communication wavelength of 1.55μm. The heater power requires to achieve switching action is about 15mW. The testing results show that the extinction ratio and switching response time are 14dB and 2ms, respectively.

  15. Assessment of laser tracking and data transfer for underwater optical communications

    NASA Astrophysics Data System (ADS)

    Watson, Malcolm A.; Blanchard, Paul M.; Stace, Chris; Bhogul, Priya K.; White, Henry J.; Kelly, Anthony E.; Watson, Scott; Valyrakis, Manousos; Najda, Stephen P.; Marona, Lucja; Perlin, Piotr

    2014-10-01

    We report on an investigation into optical alignment and tracking for high bandwidth, laser-based underwater optical communication links. Link acquisition approaches (including scanning of narrow laser beams versus a wide-angle `beacon' approach) for different underwater laser-based communications scenarios are discussed. An underwater laserbased tracking system was tested in a large water flume facility using water whose scattering properties resembled that of a turbid coastal or harbour region. The lasers used were state-of-the-art, temperature-controlled, high modulation bandwidth gallium nitride (GaN) devices. These operate at blue wavelengths and can achieve powers up to ~100 mW. The tracking performance and characteristics of the system were studied as the light-scattering properties of the water were increased using commercial antacid (Maalox) solution, and the results are reported here. Optical tracking is expected to be possible even in high scattering water environments, assuming better components are developed commercially; in particular, more sensitive detector arrays. High speed data transmission using underwater optical links, based on blue light sources, is also reported.

  16. Method and apparatus for use of III-nitride wide bandgap semiconductors in optical communications

    DOEpatents

    Hui, Rongqing; Jiang,Hong-Xing; Lin, Jing-Yu

    2008-03-18

    The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

  17. Optical Frequency Combs From Semiconductor Lasers and Applications in Ultrawideband Signal Processing and Communications

    NASA Astrophysics Data System (ADS)

    Delfyett, Peter J.; Gee, Sangyoun; Choi, Myoung-Taek; Izadpanah, Hossein; Lee, Wangkuen; Ozharar, Sarper; Quinlan, Franklyn; Yilmaz, Tolga

    2006-07-01

    Modelocked semiconductor lasers are used to generate a set of phase-locked optical frequencies on a periodic grid. The periodic and phase coherent nature of the optical frequency combs makes it possible for the realization of high-performance optical and RF arbitrary-waveform synthesis. In addition, the resulting optical frequency components can be used for communication applications relying on direct detection, dense wavelength division multiplexing (WDM), coherent-detection WDM, optical time-division multiplexing, and optical code division multiple access. This paper highlights the recent results in the use of optical frequency combs generated from semiconductors for ultrawideband signal processing and communication applications.

  18. System and method that suppresses intensity fluctuations for free space high-speed optical communication

    DOEpatents

    Berman, Gennady P.; Bishop, Alan R.; Nguyen, Dinh C.; Chernobrod, Boris M.; Gorshkov, Vacheslav N.

    2009-10-13

    A high-speed (Gbps), free space optical communication system is based on spectral encoding of radiation from a wide band light source, such as a laser. By using partially coherent laser beams in combination with a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km. To suppress the intensity fluctuations due to atmospheric turbulence, a source with partial transverse coherence in combination with slow response time photodetector is used. Information is encoded in the spectral domain of a wideband optical source by modulation of spectral amplitudes. A non-coherent light source with wide spectrum (an LED, for example) may be used for high-speed communication over short (less than about a mile) distances.

  19. Fade-resistant forward error correction method for free-space optical communications systems

    DOEpatents

    Johnson, Gary W.; Dowla, Farid U.; Ruggiero, Anthony J.

    2007-10-02

    Free-space optical (FSO) laser communication systems offer exceptionally wide-bandwidth, secure connections between platforms that cannot other wise be connected via physical means such as optical fiber or cable. However, FSO links are subject to strong channel fading due to atmospheric turbulence and beam pointing errors, limiting practical performance and reliability. We have developed a fade-tolerant architecture based on forward error correcting codes (FECs) combined with delayed, redundant, sub-channels. This redundancy is made feasible though dense wavelength division multiplexing (WDM) and/or high-order M-ary modulation. Experiments and simulations show that error-free communications is feasible even when faced with fades that are tens of milliseconds long. We describe plans for practical implementation of a complete system operating at 2.5 Gbps.

  20. Review of competing technologies for multigigabit ultralong-span fiber optic communication systems

    NASA Astrophysics Data System (ADS)

    Demokan, M. Suleyman

    1993-05-01

    Advances in conventional technologies are reviewed first. The contributions of various components, namely optical amplifiers, external modulators, tunable and narrow-linewidth lasers, high-sensitivity and high-speed detectors, and dispersion-shifted fibers, to the realization of higher speed and longer span fiber communications are discussed. The effect of techniques such as time-division and wavelength-division multiplexing, coherent detection, and dispersion compensation is explored. Optical soliton transmission is then reviewed as an alternative technology. Finally, mid-infrared communications based on new fluoride fibers and associated transmitters and receivers are considered. The author's opinions on the prospects for each approach, in the context of their limitations, are presented.

  1. The affection analysis and compensation for atmospheric overfall in free space optical communication system

    NASA Astrophysics Data System (ADS)

    Yuan, Xiuhua; Wang, Jin; Huang, Dexiu; Liu, Deming

    2004-12-01

    The Free Space optical communication (FSO) or wireless optical communication, utilizes the atmospheric medium as transmission channel, where random variety such as fog, atomy and atmosphere flash and the atmospheric turbulence will badly affect the propagation of light, the receiving signal is easily swung and drifted with the change of weather. In this paper, we discussed the attenuation of the atmospheric channel and analyzed the signal characteristics in the condition of the atmospheric overfall, for the OOK modulation, discussed the receiving signal distribution in the atmospheric channel taking account for the noise gain of the light detector, and based on the principle of the Hartman-Shack sensor, we designed a wave-front distortion compensation system with fiber coupler. The signal fading resulted from wave-front phase distortion was compensated effectively by using the compensation system.

  2. Design considerations for a fiber optic communications network for power systems

    SciTech Connect

    Kirkham, H.; Johnston, A.R.; Allen, G.D.

    1993-08-01

    The design of a fiber optic communication network for monitoring and control in power systems is discussed. It is shown that by appropriate choice of protocols, a fault-tolerant system can be built that operates in any arbitrary configuration. Since the network is based on fiber optics, it can be made fast enough for substation monitoring and control. In this application, a relatively small number of cables is required to implement a high reliability system. The network can also be used for distribution automation. In this application the network is required to reach all parts of the power system, and the fiber cable itself becomes a significant fraction of the cost of communications. However, since many applications can be supported at once, the cost per function can be reasonable.

  3. Cost effective optical coupling for enhanced rate polymer optical fiber communication

    NASA Astrophysics Data System (ADS)

    Chandrappan, Jayakrishnan; Zhang, Jing; Ramana, Pamidighantam V.; Lau, John Hon Shing; Kwong, Dim Lee

    2008-02-01

    Recent developments in the short distance communication have made polymer optical fibers (POF) an attractive product in the high speed data communication market. The requirement of a large bandwidth, low cost, light weight and flexibility in installation have placed them over the copper cables especially in applications like home networking and automotives. Since POFs are large core multimoded fibers, their band width is limited by intermodal dispersion. This confines POFs application to low data rate short distance communications. Restrictive mode launchers (RML) and higher order mode strippers placed in the data link helps to reduce the intermodal dispersion. The techniques used to implement these signal conditioners should be simple and cost effective to keep POFs attractive in the short distance communication. In this paper we explore the possibility of integrating the RML and mode stripping elements in the transmitter and receiver package itself. The pre-designed optical signal conditioning elements are projected to get molded in the plastic packages and are fiber plug in modules. This connector less package design, universal to any light source proposes to enhance the data rate and is widely manufacturable at an ease of installation and low cost.

  4. Statistical distribution of the optical intensity obtained using a Gaussian Schell model for space-to-ground link laser communications

    NASA Astrophysics Data System (ADS)

    Li, Mengnan; Tan, Liying; Ma, Jing; Yu, Siyuan; Yang, Qingbo; Wu, Jiajie

    2016-05-01

    Based on the characteristics of the laser device and the inevitable error of the processing technique, a laser beam emitted from a communication terminal can be represented by the Gaussian Schell model (GSM). In space-to-ground link laser communications, the optical intensity is affected by the source coherence parameter and the zenith angle. With full consideration of these two parameters, the statistical distribution model of the optical intensity with a GSM laser in both downlink and uplink is derived. The simulation results indicate that increasing the source coherence parameter has an effect on the statistical distribution of the optical intensity; this effect is highly similar to the effect of a larger zenith angle. The optical intensity invariably degrades with increasing source coherence parameter or zenith angle. The results of this work can promote the improvement of the redundancy design of a laser communication receiver system.

  5. Optimization of the input losses in fiber-optic communications with an acousto-optic all-optical switch.

    PubMed

    Danilyan, A V; Shulgin, V A; Chernov, V E

    2006-06-20

    We study optical losses in the single-mode fiber system with an all-optical switch based on the anisotropic acousto-optic (AO) TeO(2) 2D deflector. It is shown, theoretically and experimentally, that the mismatch of the output-fiber mode profile and the switched optical beam shape depends significantly on the monochromaticity of the light beam and is determined by the frequency dispersion of the laser beam diffracted on a Bragg AO cell. A quantitative analysis of the dependence of the input optical losses on the spectral width of the light beam is presented. PMID:16778941

  6. Performance analysis of coherent wireless optical communications with atmospheric turbulence.

    PubMed

    Niu, Mingbo; Song, Xuegui; Cheng, Julian; Holzman, Jonathan F

    2012-03-12

    Coherent wireless optical communication systems with heterodyne detection are analyzed for binary phase-shift keying (BPSK), differential PSK (DPSK), and M-ary PSK over Gamma-Gamma turbulence channels. Closed-form error rate expressions are derived using a series expansion approach. It is shown that, in the special case of K-distributed turbulence channel, the DPSK incurs a 3 dB signal-to-noise ratio (SNR) penalty compared to BPSK in the large SNR regime. The outage probability is also obtained, and a detailed outage truncation error analysis is presented and used to assess the accuracy in system performance estimation. It is shown that our series error rate expressions are simple to use and highly accurate for practical system performance estimation. PMID:22418534

  7. SILEX: Overview on the European optical communications programme

    NASA Astrophysics Data System (ADS)

    Laurent, B.

    1995-10-01

    SILEX (Semi-Conducteur Intersatellite Link Experiment) is the first civilian optical communications programme (in the frame of ESA DRTM). It will demonstrate in 1997 high data rate transmission between a Low Earth Orbit Satellite (SPOT IV, built by MMS for CNES) and a Geostationnary spacecraft (ARTEMIS, realized by ALENIA for ESA). After the opto/mechanical/thermal qualification obtained mid of 1994, the SILEX programme is entered in an intensive phase with: — the integration/validation for the LEO flight model (PASTEL)— the preparation of integration of the GEO qualification STM and electrical/SW models (OPALE) The article describes the overall development status including the major terminal validation steps as well as the significant technological progress obtained through the qualification at equipment/terminal level.

  8. Detection alternatives for pulse position modulation (PPM) optical communication

    NASA Astrophysics Data System (ADS)

    Mecherle, G. Stephen

    1986-01-01

    An analysis is conducted for alternative optical communication detection strategies employing pulse position modulation (PPM). In cases without error correcting codes, the M-ary maximum count strategy is noted to furnish the best performance on the basis of its maximum a posteriori character. In cases with error correcting codes, the decoder has the additional option of hard or soft decisioning and each of the unencoded detection schemes can interface directly with a hard decision decoder. Illustrative hard decision coding gains are evaluated for M-ary Reed-Solomon and binary BCH codes with an APD receiver. The performance of rate-1/2 Reed-Solomon codes is compared for Delta-max and threshold soft decision strategies with an APD receiver.

  9. Ionophore-Based Optical Sensors

    NASA Astrophysics Data System (ADS)

    Mistlberger, Günter; Crespo, Gastón A.; Bakker, Eric

    2014-06-01

    This review provides an overview of the key aspects of designing ionophore-based optical sensors (IBOS). Exact response functions are developed and compared with a simplified, generalized equation. We also provide a brief introduction into less established but promising working principles, namely dynamic response and exhaustive exchange. Absorbance and fluorescence are the main optical readout strategies used in the evaluation of a sensor response, but they usually require a robust referencing technique for real-world applications. Established referencing schemes using IBOS as well as those from other optical sensors are also discussed. Finally, the power of recently developed photoresponsive ion extraction/release systems is outlined and discussed in view of dynamically switchable IBOS or regenerative exhaustive exchange IBOS.

  10. Ultra-high speed communications based on solitons in fibers

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira

    2000-10-01

    The citation of the Maxwell prize reads: ``For innovative discoveries and seminal contributions to the theories of nonlinear drift wave turbulence, Alfvén wave propagation in laboratory and space plasmas, and optical solitons and their application to high speed communication". The prize is given to three somewhat unrelated contributions made during the course of my career as a plasma physicist. Traditionally an award talk summarizes works related to the citation. However, because of the diversified contents of the citations, I prepared my talk with the focus only on the last topic because some of the audience may be of more expertise on the other subjects. I apologize for the fact that the talk may be worth only one third of the prize. Multi-Terabits’s, ultra-high speed optical transmissions over several thousand kilometers on fibers are becoming reality and are expected to serve as the trunk line for highly demanded Internet traffics. Most of them use soliton or soliton-like RZ (Return to Zero) format in fibers with properly managed (group velocity) dispersion. These formats are the only stable envelope waveforms of light waves in fibers in the presence of Kerr (cubic) nonlineariy and dispersion with loss compensated by periodic optical amplifications. In practice, the transmission systems utilize the all-optical transmission concept and the nonlinear Schrodinger equation assisted by the split step numerical solutions as the master equation to describe the information transfer in fibers. All these facts are the outcome of research on optical solitons in fibers. The talk presents a brief historical development of the soliton based high-speed communications followed by current status of ultra-high speed communications by means of solitons as well as by other formats. Although the talk may not be of a core interest of plasma physics community, it presents an interesting example of a useful by-product of plasma physics research.

  11. Information Trade-Offs for Optical Quantum Communication

    NASA Astrophysics Data System (ADS)

    Wilde, Mark M.; Hayden, Patrick; Guha, Saikat

    2012-04-01

    Recent work has precisely characterized the achievable trade-offs between three key information processing tasks—classical communication (generation or consumption), quantum communication (generation or consumption), and shared entanglement (distribution or consumption), measured in bits, qubits, and ebits per channel use, respectively. Slices and corner points of this three-dimensional region reduce to well-known protocols for quantum channels. A trade-off coding technique can attain any point in the region and can outperform time sharing between the best-known protocols for accomplishing each information processing task by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this Letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space or fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels.

  12. Information trade-offs for optical quantum communication.

    PubMed

    Wilde, Mark M; Hayden, Patrick; Guha, Saikat

    2012-04-01

    Recent work has precisely characterized the achievable trade-offs between three key information processing tasks-classical communication (generation or consumption), quantum communication (generation or consumption), and shared entanglement (distribution or consumption), measured in bits, qubits, and ebits per channel use, respectively. Slices and corner points of this three-dimensional region reduce to well-known protocols for quantum channels. A trade-off coding technique can attain any point in the region and can outperform time sharing between the best-known protocols for accomplishing each information processing task by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this Letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space or fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels. PMID:22540777

  13. MIMO free-space optical communication employing coherent BPOLSK modulation in atmospheric optical turbulence channel with pointing errors

    NASA Astrophysics Data System (ADS)

    Prabu, K.; Kumar, D. Sriram

    2015-05-01

    An optical wireless communication system is an alternative to radio frequency communication, but atmospheric turbulence induced fading and misalignment fading are the main impairments affecting an optical signal when propagating through the turbulence channel. The resultant of misalignment fading is the pointing errors, it degrades the bit error rate (BER) performance of the free space optics (FSO) system. In this paper, we study the BER performance of the multiple-input multiple-output (MIMO) FSO system employing coherent binary polarization shift keying (BPOLSK) in gamma-gamma (G-G) channel with pointing errors. The BER performance of the BPOLSK based MIMO FSO system is compared with the single-input single-output (SISO) system. Also, the average BER performance of the systems is analyzed and compared with and without pointing errors. A novel closed form expressions of BER are derived for MIMO FSO system with maximal ratio combining (MRC) and equal gain combining (EGC) diversity techniques. The analytical results show that the pointing errors can severely degrade the performance of the system.

  14. Next-generation optical wireless communications for data centers

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi

    2015-01-01

    Data centers collect and process information with a capacity that has been increasing from year to year at an almost exponential pace. Traditional fiber/cable data center network interconnections suffer from bandwidth overload, as well as flexibility and scalability issues. Therefore, a technology-shift from the fiber and cable to wireless has already been initiated in order to meet the required data-rate, flexibility and scalability demands for next-generation data center network interconnects. In addition, the shift to wireless reduces the volume allocated to the cabling/fiber and increases the cooling efficiency. Optical wireless communication (OWC), or free space optics (FSO), is one of the most effective wireless technologies that could be used in future data centers and could provide ultra-high capacity, very high cyber security and minimum latency, due to the low index of refraction of air in comparison to fiber technologies. In this paper we review the main concepts and configurations for next generation OWC for data centers. Two families of technologies are reviewed: the first technology regards interconnects between rack units in the same rack and the second technology regards the data center network that connects the server top of rack (TOR) to the switch. A comparison between different network technologies is presented.

  15. Ergodic capacity comparison of optical wireless communications using adaptive transmissions.

    PubMed

    Hassan, Md Zoheb; Hossain, Md Jahangir; Cheng, Julian

    2013-08-26

    Ergodic capacity is investigated for the optical wireless communications employing subcarrier intensity modulation with direct detection, and coherent systems with and without polarization multiplexing over the Gamma-Gamma turbulence channels. We consider three different adaptive transmission schemes: (i) variable-power, variable-rate adaptive transmission, (ii) complete channel inversion with fixed rate, and (iii) truncated channel inversion with fixed rate. For the considered systems, highly accurate series expressions for ergodic capacity are derived using a series expansion of the modified Bessel function and the Mellin transformation of the Gamma-Gamma random variable. Our asymptotic analysis reveals that the high SNR ergodic capacities of coherent, subcarrier intensity modulated, and polarization multiplexing systems gain 0.33 bits/s/Hz, 0.66 bits/s/Hz, and 0.66 bits/s/Hz respectively with 1 dB increase of average transmitted optical power. Numerical results indicate that a polarization control error less than 10° has little influence on the capacity performance of polarization multiplexing systems. PMID:24105580

  16. Comparison of direct and heterodyne detection optical intersatellite communication links

    NASA Technical Reports Server (NTRS)

    Chen, C. C.; Gardner, C. S.

    1987-01-01

    The performance of direct and heterodyne detection optical intersatellite communication links are evaluated and compared. It is shown that the performance of optical links is very sensitive to the pointing and tracking errors at the transmitter and receiver. In the presence of random pointing and tracking errors, optimal antenna gains exist that will minimize the required transmitter power. In addition to limiting the antenna gains, random pointing and tracking errors also impose a power penalty in the link budget. This power penalty is between 1.6 to 3 dB for a direct detection QPPM link, and 3 to 5 dB for a heterodyne QFSK system. For the heterodyne systems, the carrier phase noise presents another major factor of performance degradation that must be considered. In contrast, the loss due to synchronization error is small. The link budgets for direct and heterodyne detection systems are evaluated. It is shown that, for systems with large pointing and tracking errors, the link budget is dominated by the spatial tracking error, and the direct detection system shows a superior performance because it is less sensitive to the spatial tracking error. On the other hand, for systems with small pointing and tracking jitters, the antenna gains are in general limited by the launch cost, and suboptimal antenna gains are often used in practice. In which case, the heterodyne system has a slightly higher power margin because of higher receiver sensitivity.

  17. Measurement-based noiseless linear amplification for quantum communication

    NASA Astrophysics Data System (ADS)

    Chrzanowski, Helen M.; Walk, Nathan; Assad, Syed M.; Janousek, Jiri; Hosseini, Sara; Ralph, Timothy C.; Symul, Thomas; Lam, Ping Koy

    2014-04-01

    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require advanced experimental techniques such as noiseless amplification. Recently, it was shown that the benefits of noiseless amplification could be extracted by performing a post-selective filtering of the measurement record to improve the performance of quantum key distribution. We apply this protocol to entanglement degraded by transmission loss of up to the equivalent of 100 km of optical fibre. We measure an effective entangled resource stronger than that achievable by even a maximally entangled resource passively transmitted through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime. The measurement-based noiseless linear amplifier offers two advantages over its physical counterpart: ease of implementation and near-optimal probability of success. It should provide an effective and versatile tool for a broad class of entanglement-based quantum communication protocols.

  18. Active photonic sensor communication cable for field application of optical data and power transmission

    NASA Astrophysics Data System (ADS)

    Suthau, Eike; Rieske, Ralf; Zerna, Thomas

    2014-10-01

    Omitting electrically conducting wires for sensor communication and power supply promises protection for sensor systems and monitored structures against lightning or high voltages, prevention of explosion hazards, and reduction of susceptibility to tampering. The ability to photonically power remote systems opens up the full range of electrical sensors. Power-over-fiber is an attractive option in electromagnetically sensitive environments, particularly for longterm, maintenance-free applications. It can deliver uninterrupted power sufficient for elaborate sensors, data processing or even actuators alongside continuous high speed data communication for remote sensor application. This paper proposes an active photonic sensor communication system, which combines the advantages of optical data links in terms of immunity to electromagnetic interference (EMI), high bandwidth, hardiness against tampering or eavesdropping, and low cable weight with the robustness one has come to expect from industrial or military electrical connectors. An application specific integrated circuit (ASIC) is presented that implements a closed-loop regulation of the sensor power supply to guarantee continuous, reliable data communications while maintaining a highly efficient, adaptive sensor supply scheme. It is demonstrated that the resulting novel photonic sensor communication cable can handle sensors and actuators differing orders of magnitude with respect to power consumption. The miniaturization of the electro-optical converters and driving electronics is as important to the presented development as the energy efficiency of the detached, optically powered sensor node. For this reason, a novel photonic packaging technology based on wafer-level assembly of the laser power converters by means of passive alignment will be disclosed in this paper.

  19. Optical wireless communication through fog in the presence of pointing errors

    NASA Astrophysics Data System (ADS)

    Kedar, Debbie; Arnon, Shlomi

    2003-08-01

    Terrestrial optical wireless communication (OWC) is emerging as a promising technology, which makes connectivity possible between high-rise buildings and metropolitan and intercity communication infrastructures. A light beam carries the information, which facilitates extremely high data rates. However, strict alignment between the transmitter and the receiver must be maintained at all times, and a pointing error can result in a total severance of the communication link. In addition, the presence of fog and haze in the propagation channel hampers OWC as the small water droplets scatter the propagating light. This causes attenuation due to the resultant spatial, angular, and temporal spread of the light signal. Furthermore, the ensuing low visibility may impede the operation of the tracking and pointing system so that pointing errors occur. We develop a model of light transmission through fogs of different optical densities and types using Monte Carlo simulations. Based on this model, the performance of OWC in fogs is evaluated at different wavelengths. The handicap of a transceiver pointing error is added to the model, and the paradoxically advantageous aspects of the transmission medium are exposed. The concept of a variable field of view receiver for narrow-beam OWC is studied, and the possibility of thus enhancing communication system performance through fog in an inexpensive and simple way is indicated.

  20. Joint digital signal processing for superchannel coherent optical communication systems.

    PubMed

    Liu, Cheng; Pan, Jie; Detwiler, Thomas; Stark, Andrew; Hsueh, Yu-Ting; Chang, Gee-Kung; Ralph, Stephen E

    2013-04-01

    Ultra-high-speed optical communication systems which can support ≥ 1Tb/s per channel transmission will soon be required to meet the increasing capacity demand. However, 1Tb/s over a single carrier requires either or both a high-level modulation format (i.e. 1024QAM) and a high baud rate. Alternatively, grouping a number of tightly spaced "sub-carriers" to form a terabit superchannel increases channel capacity while minimizing the need for high-level modulation formats and high baud rate, which may allow existing formats, baud rate and components to be exploited. In ideal Nyquist-WDM superchannel systems, optical subcarriers with rectangular spectra are tightly packed at a channel spacing equal to the baud rate, thus achieving the Nyquist bandwidth limit. However, in practical Nyquist-WDM systems, precise electrical or optical control of channel spectra is required to avoid strong inter-channel interference (ICI). Here, we propose and demonstrate a new "super receiver" architecture for practical Nyquist-WDM systems, which jointly detects and demodulates multiple channels simultaneously and mitigates the penalties associated with the limitations of generating ideal Nyquist-WDM spectra. Our receiver-side solution relaxes the filter requirements imposed on the transmitter. Two joint DSP algorithms are developed for linear ICI cancellation and joint carrier-phase recovery. Improved system performance is observed with both experimental and simulation data. Performance analysis under different system configurations is conducted to demonstrate the feasibility and robustness of the proposed joint DSP algorithms. PMID:23571924

  1. Secured Optical Communications Using Quantum Entangled Two-Photon Transparency Modulation

    NASA Technical Reports Server (NTRS)

    Kojima, Jun (Inventor); Nguyen, Quang-Viet (Inventor); Lekki, John (Inventor)

    2015-01-01

    A system and method is disclosed wherein optical signals are coded in a transmitter by tuning or modulating the interbeam delay time (which modulates the fourth-order coherence) between pairs of entangled photons. The photon pairs are either absorbed or not absorbed (transparent) by an atomic or molecular fluorescer in a receiver, depending on the inter-beam delay that is introduced in the entangled photon pairs. Upon the absorption, corresponding fluorescent optical emissions follow at a certain wavelength, which are then detected by a photon detector. The advantage of the disclosed system is that it eliminates a need of a coincidence counter to realize the entanglement-based secure optical communications because the absorber acts as a coincidence counter for entangled photon pairs.

  2. Pulse position modulated (PPM) ground receiver design for optical communications from deep space

    NASA Astrophysics Data System (ADS)

    Biswas, Abhijit; Vilnrotter, Victor; Farr, William H.; Fort, D.; Sigman, E.

    2002-04-01

    Pulse position modulation (PPM) provides a means of using high peak power lasers for transmitting communications signals from planetary spacecraft to earth-based receiving stations. Large aperture (approximately 10 m diameter) telescopes will be used to collect and focus the laser communications signal originating from a deep space transmitter on to a PPM receiver. Large area (1 - 3 mm diameter) sensitive detectors, preceded by appropriate narrow (0.1 - 0.2 nm) optical band-pass filters and followed by low-noise, high-gain, amplifiers will serve as the PPM receiver front end. A digital assembly will form the backbone of the receiver. The PPM receiver will achieve and maintain slot synchronization based on sub slot sums generated by a field programmable-gated array (FPGA). Spacecraft dynamics and timing issues between the ground- based receiver and the transmitter on board the spacecraft must be taken into account. In the present report, requirements and design of a prototype PPM receiver being developed over the next year will be elaborated. The design is driven by the need to demonstrate and validate PPM reception using a variety of detectors under simulated conditions representative of those to be encountered in a deep space optical communications link.

  3. Brief state-of-the-art review on optical communications for the NASA ISES workshop

    NASA Technical Reports Server (NTRS)

    Hendricks, Herbert D.

    1990-01-01

    The current state of the art of optical communications is briefly reviewed. This review covers NASA programs, DOD and other government agency programs, commercial aerospace programs, and foreign programs. Included is a brief summary of a recent NASA workshop on optical communications. The basic conclusions from all the program reviews is that optical communications is a technology ready to be accepted but needed to be demonstrated. Probably the most advanced and sophisticated optical communications system is the Laser Intersatellite Transmission Experiment (LITE) system developed for flight on the Advanced Communications Technology Satellite (ACTS). Optical communications technology is available for the applications of data communications at data rates in the under 300 MBits/sec for nearly all applications under 2 times GEO distances. Applications for low-earth orbiter (LEO) to ground will allow data rates in the multi-GBits/sec range. Higher data rates are limited by currently available laser power. Phased array lasers offer technology which should eliminate this problem. The major problem of cloud coverage can probably be eliminated by look ahead pointing, multiple ground stations, and knowledge of weather conditions to control the pointing. Most certainly, optical communications offer a new spectral region to relieve the RF bands and very high data communications rates that will be required in less than 10 years to solve the communications problems on Earth.

  4. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range

    NASA Astrophysics Data System (ADS)

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-04-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications.

  5. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range.

    PubMed

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  6. Nanoscale on-chip all-optical logic parity checker in integrated plasmonic circuits in optical communication range

    PubMed Central

    Wang, Feifan; Gong, Zibo; Hu, Xiaoyong; Yang, Xiaoyu; Yang, Hong; Gong, Qihuang

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154

  7. 78 FR 16296 - Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and Products...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-14

    ... optic communications, components thereof, and products containing the same by reason of infringement of certain claims of U.S. Patent Nos. 6,947,456 and 5,596,595 (collectively, ``Asserted Patents''). 77 FR... COMMISSION Certain Optoelectronic Devices for Fiber Optic Communications, Components Thereof, and...

  8. OPTICAL SOLITONS: Fibreoptic communication lines with distributed Raman amplification: Numerical simulation

    NASA Astrophysics Data System (ADS)

    Nasieva, I. O.; Fedoruk, Mikhail P.

    2003-10-01

    The properties of optical solitons in variable-dispersion fibreoptic communication lines in which distributed Raman amplification of optical signals is used are studied by numerical simulation. It is shown that solitons can serve as carriers of information in communication systems with a data transmission rate exceeding 10 Gbit s-1.

  9. Support for the U.S. precision optics manufacturing base center for optics manufacturing

    NASA Astrophysics Data System (ADS)

    Leshne, Robert H.

    1989-12-01

    The importance of optics to the economic and military strength of the United States is well known. Advances in optical technology have substantial leverage and are closely related to advances in associated technologies (i.e., imaging, sensing, communications, guidance control, etc.). However, the lead in manufacturing and fabrication of optical components and systems has been lost to our world competitors, especially Japan and other Pacific Rim countries. The optics industrial base has been in a slow but constant decline since the 1970's. The shift in business strategy from manufacturing emphasis to purchasing from worldwide resources has resulted in many U.S. "manufacturers" becoming importers. Optics employment dropped 50% from 1981 to 1986. Imports currently dominate both the U.S. commercial and DOD optics markets.

  10. Comparison of satellite and fiber optics technologies for intercity and intercontinental communications

    NASA Astrophysics Data System (ADS)

    Sharifi, M. Hossein; Arozullah, Mohammed

    The applications of satellite and fiber optic technologies to the design of intercity and intercontinental communications networks are examined. Satellite technology including space and ground segments, and advancements and operational requirements for underwater and land fiber optics communications systems are discussed. Communications satellites and fiber optics are compared in terms of physical implementation, switching requirements, transmission parameters, availability, cost, system flexibility, transmission quality, and applications. The cost of point-to-point transmission of 60 Mbps data using satellite, fiber optics, and microwave systems is evaluated. It is observed that satellite systems are the most cost-effective and flexible methods for providing transmission media for distances greater than about 700 km.

  11. Optical Microangiography Based on Optical Coherence Tomography

    NASA Astrophysics Data System (ADS)

    Reif, Roberto; Wang, Ruikang K.

    Proper homeostasis regulation of in vivo biological systems requires microvascular blood perfusion, which is the process of delivering blood into the tissue's capillary beds. Abnormal tissue vascularization has been associated with various diseases such as cancer, diabetes, neurological disorders, wounds, and inflammation. Understanding the changes in the vascular network or microangiography will have an important role in determining the causes and developing potential treatments for these diseases. Optical coherence tomography (OCT) is a noninvasive method for imaging three-dimensional biological tissues with high resolution (~10 µm) and without requiring the use of contrast agents. In this chapter we review several techniques for using OCT to determine blood flow velocities and the vessel morphology (optical microangiography). Different techniques will be discussed with a brief explanation of their limitations. Also, methods for quantifying these images are presented, as well as the depiction of several applications.

  12. Photonic crystal-based optical filters for operating in second and third optical fiber windows

    NASA Astrophysics Data System (ADS)

    Zamani, Mehdi

    2016-04-01

    In this paper, the filtering properties of photonic crystals (PCs) to perform narrow-channel transmission-type filters in second and third optical fiber telecommunication windows have been studied. Filtration of these zero dispersion and low-loss windows have simultaneously been established by utilizing of a triple-cavity transmission-type one-dimensional PC that provides perfect transmittances and narrow-channels at corresponding wavelengths. Such PC-based optical filter can be used in wavelength division multiplexing (WDM) optical communications systems.

  13. Communication system technology for demonstration of BB84 quantum key distribution in optical aircraft downlinks

    NASA Astrophysics Data System (ADS)

    Moll, Florian; Nauerth, Sebastian; Fuchs, Christian; Horwath, Joachim; Rau, Markus; Weinfurter, Harald

    2012-10-01

    Quantum Key Distribution (QKD), either fiber based or free-space, allows for provably secure key distribution solely based on the laws of quantum mechanics. Feasibility of QKD systems in aircraft-ground links was demonstrated with a successful key exchange. Experiment flights were undertaken during night time at the site of the German Aerospace Center (DLR) Oberpfaffenhofen, Germany. The aircraft was a Dornier 228 equipped with a laser communication terminal, originally designed for optical data downlinks with intensity modulation and direct detection. The counter terminal on ground was an optical ground station with a 40 cm Cassegrain type receiver telescope. Alice and Bob, as the transmitter and receiver systems usually are called in QKD, were integrated in the flight and ground terminals, respectively. A second laser source with 1550 nm wavelength was used to transmit a 100 MHz signal for synchronization of the two partners. The so called BB84 protocol, here implemented with faint polarization encoded pulses at 850nm wavelength, was applied as key generation scheme. Within two flights, measurements of the QKD and communication channel could be obtained with link distance of 20 km. After link acquisition, the tracking systems in the aircraft and on ground were able to keep lock of the narrow QKD beam. Emphasis of this paper is put on presentation of the link technology, i.e. link design and modifications of the communication terminals. First analysis of link attenuation, performance of the QKD system and scintillation of the sync signal is also addressed.

  14. An Extremely Low Power Quantum Optical Communication Link for Autonomous Robotic Explorers

    NASA Technical Reports Server (NTRS)

    Lekki, John; Nguyen, Quang-Viet; Bizon, Tom; Nguyen, Binh; Kojima, Jun

    2007-01-01

    One concept for planetary exploration involves using many small robotic landers that can cover more ground than a single conventional lander. In addressing this vision, NASA has been challenged in the National Nanotechnology Initiative to research the development of miniature robots built from nano-sized components. These robots have very significant challenges, such as mobility and communication, given the small size and limited power generation capability. The research presented here has been focused on developing a communications system that has the potential for providing ultra-low power communications for robots such as these. In this paper an optical communications technique that is based on transmitting recognizable sets of photons is presented. Previously pairs of photons that have an entangled quantum state have been shown to be recognizable in ambient light. The main drawback to utilizing entangled photons is that they can only be generated through a very energy inefficient nonlinear process. In this paper a new technique that generates sets of photons from pulsed sources is described and an experimental system demonstrating this technique is presented. This technique of generating photon sets from pulsed sources has the distinct advantage in that it is much more flexible and energy efficient, and is well suited to take advantage of the very high energy efficiencies that are possible when using nano scale sources. For these reasons the communication system presented in this paper is well suited for use in very small, low power landers and rovers. In this paper a very low power optical communications system for miniature robots, as small as 1 cu cm is addressed. The communication system is a variant of photon counting communications. Instead of counting individual photons the system only counts the arrival of time coincident sets of photons. Using sets of photons significantly decreases the bit error rate because they are highly identifiable in the

  15. Feasibility of utilizing Cherenkov Telescope Array gamma-ray telescopes as free-space optical communication ground stations.

    PubMed

    Carrasco-Casado, Alberto; Vilera, Mariafernanda; Vergaz, Ricardo; Cabrero, Juan Francisco

    2013-04-10

    The signals that will be received on Earth from deep-space probes in future implementations of free-space optical communication will be extremely weak, and new ground stations will have to be developed in order to support these links. This paper addresses the feasibility of using the technology developed in the gamma-ray telescopes that will make up the Cherenkov Telescope Array (CTA) observatory in the implementation of a new kind of ground station. Among the main advantages that these telescopes provide are the much larger apertures needed to overcome the power limitation that ground-based gamma-ray astronomy and optical communication both have. Also, the large number of big telescopes that will be built for CTA will make it possible to reduce costs by economy-scale production, enabling optical communications in the large telescopes that will be needed for future deep-space links. PMID:23670767

  16. Diagonal-Axes Stage for Pointing an Optical Communications Transceiver

    NASA Technical Reports Server (NTRS)

    Regehr, Martin W.; Garkanian, Vachik

    2011-01-01

    Traditional azimuth-elevation ("az-el") stages are used to point a variety of devices ranging from large optical telescopes to tank guns. Such a stage typically has an elevation stage having a horizontal axis mounted on an azimuth stage with a vertical axis. Both stages are often motorized. Optical communications transceivers often require two-axis motorized control, as when the communications link is between a ground station and an aircraft or satellite. In such applications, the traditional azimuth-elevation stage has two important drawbacks: a gimbal lock exclusion zone at zenith and susceptibility to pointing errors caused by backlash. Az-el stages in which the azimuth stage cannot rotate a full 360deg have the additional drawback of an azimuth exclusion zone. The diagonal-axes stage described here mitigates or eliminates all of these problems. Instead of one vertical axis and one horizontal axis, a diagonal-axes stage has two horizontal axes, both oriented at 45 to the trajectory of the target. For example, a ground station located on the equator tracking a satellite with an equatorial orbit would have one axis parallel to northeast and southwest, and the other axis parallel to northwest and southeast. The diagonal-axes stage is considerably less vulnerable to backlash. If it is correctly oriented, its axes rotate in only one direction during an overhead pass by a satellite. As a result, the effects of backlash may be inherently eliminated. If the gravity-induced torque on either axis changes during the pass, then backlash may become important during the part of the pass where the gravity torque, instead of opposing the motion of the stage, pushes the stage in the direction of motion. This can result in the loss of gear-to-gear contact in one or more stages of the gear reduction mechanism. In this case, a preload spring used to eliminate backlash need only be sufficiently strong to overcome the gravity torque, i.e. it need not overcome friction in the gear

  17. Experimental implementation of fiber optic bundle array wide FOV free space optical communications receiver.

    PubMed

    Brown, Andrea M; Hahn, Daniel V; Brown, David M; Rolander, Nathan W; Bair, Chun-Huei; Sluz, Joseph E

    2012-06-20

    A gimbal-free wide field-of-regard (FOR) optical receiver has been built in a laboratory setting for proof-of-concept testing. Multiple datasets are presented that examine the overall FOR of the system and the receiver's ability to track and collect a signal from a moving source. The design is not intended to compete with traditional free space optical communication systems, but rather offer an alternative design that minimizes the number and complexity of mechanical components required at the surface of a small mobile platform. The receiver is composed of a micro-lens array and hexagonal bundles of large core optical fibers that route the optical signal to remote detectors and electronics. Each fiber in the bundle collects power from a distinct solid angle of space and a piezo-electric transducer is used to translate the micro-lens array and optimize coupling into a given fiber core in the bundle. The micro-lens to fiber bundle design is scalable, modular, and can be replicated in an array to increase aperture size. PMID:22722273

  18. On the passive probing of fiber optic quantum communication channels

    SciTech Connect

    Korol'kov, A. V.; Katamadze, K. G.; Kulik, S. P.; Molotkov, S. N.

    2010-04-15

    Avalanche photodetectors based on InGaAs:P are the most sensitive and only detectors operating in the telecommunication wavelength range 1.30-1.55 {mu}m in the fiber optic quantum cryptography systems that can operate in the single photon count mode. In contrast to the widely used silicon photodetectors for wavelengths up to 1 {mu}m operating in a waiting mode, these detectors always operate in a gated mode. The production of an electron-hole pair in the process of the absorption of a photon and the subsequent appearance of an avalanche of carriers can be accompanied by the inverse processes of the recombination and emission of photons. Such a backward emission can present a potential serious problem for the stability of fiber optic quantum cryptography systems against passive probing. The results of analyzing the detection of backscattered radiation are reported. The probability of such an emission has been estimated.

  19. Bit error rate optimization of an acousto-optic tracking system for free-space laser communications

    NASA Astrophysics Data System (ADS)

    Sofka, J.; Nikulin, V.

    2006-02-01

    Optical communications systems have been gaining momentum with the increasing demand for transmission bandwidth in the last several years. Optical cable based solutions have become an attractive alternative to copper based system in the most bandwidth demanding applications due to increased bandwidth and longer inter-repeater distances. The promise of similar benefits over radio communications systems is driving the research into free space laser communications. Along with increased communications bandwidth, a free space laser communications system offers lower power consumption and the possibility for covert data links due to the concentration of the energy of the laser into a narrow beam. A narrow beam, however, results in a requirement for much more accurate and agile steering, so that a data link can be maintained in a scenario of communication platforms in relative motion or in the presence of vibrations. This paper presents a laser beam tracking system employing an acousto-optic cell capable of deflecting a laser beam at a very high rate (order of tens of kHz). The tracking system is subjected to vibrations to simulate a realistic implementation, resulting in the increase of BER. The performance of the system can be significantly improved through digital control. A constant gain controller is complemented by a Kalman filter the parameters of which are optimized to achieve the lowest possible BER for a given vibrations spectrum.

  20. Spin nano-oscillator-based wireless communication

    NASA Astrophysics Data System (ADS)

    Choi, Hyun Seok; Kang, Sun Yool; Cho, Seong Jun; Oh, Inn-Yeal; Shin, Mincheol; Park, Hyuncheol; Jang, Chaun; Min, Byoung-Chul; Kim, Sang-Il; Park, Seung-Young; Park, Chul Soon

    2014-06-01

    Spin-torque nano-oscillators (STNOs) have outstanding advantages of a high degree of compactness, high-frequency tunability, and good compatibility with the standard complementary metal-oxide-semiconductor process, which offer prospects for future wireless communication. There have as yet been no reports on wireless communication using STNOs, since the STNOs also have notable disadvantages such as lower output power and poorer spectral purity in comparison with those of LC voltage-controlled oscillators. Here we show that wireless communication is achieved by a proper choice of modulation scheme despite these drawbacks of STNOs. By adopting direct binary amplitude shift keying modulation and non-coherent demodulation, we demonstrate STNO-based wireless communication with 200-kbps data rate at a distance of 1 m between transmitter and receiver. It is shown, from the analysis of STNO noise, that the maximum data rate can be extended up to 1.48 Gbps with 1-ns turn-on time. For the fabricated STNO, the maximum data rate is 5 Mbps which is limited by the rise time measured in the total system. The result will provide a viable route to real microwave application of STNOs.

  1. A High-Speed Optical Modem Communication System for CORK Seafloor Observatories

    NASA Astrophysics Data System (ADS)

    Farr, N.; Tivey, M.; Ware, J.; Pontbriand, C.; Pelletier, L. P.

    2014-12-01

    High-speed communications underwater is an increasing requirement for data intensive seafloor sensors. Acoustic modems provide dependable long-range communications underwater, but data rates are limited to <57Kbps. Free-water optical modems (OMs) offer high data rate, 10Mbps communications over a range of 200 m - a distance for ROVs, AUVs or wire-lowered packages to communicate without the need to directly plug-in or retrieve the instrument. Over the past 4 years, we have demonstrated the functionality and utility of OM technology using a CORK borehole observatory as a test case. A CORK represents all of the basic components required for a seafloor observatory: a stable environment for long-term continuous measurements of earth and ocean phenomena, access to a unique environment below the seafloor and a standard communication interface. The CORK-OM features a high-bandwidth, low-latency optical system based on LED emitters and PMT receivers and an acoustic command and control system. OM tests established a communication link from 20 to 200 meters range at rates of 1, 5 and 10 Mbps with no bit errors. The seafloor OM was plugged into the CORK's existing underwater wet mateable connector and provided additional power to the CORK to boost the data rate to 1 Hz from the normal 1 minute sample period. To communicate with the seafloor CORK-OM, a number of different modalities were used. One method was an OM mounted to a CTD frame on a lowered wire from a ship with an SDSL link over the conducting wire. Other methods utilized OMs mounted to both ROV Jason and submersible Alvin. We deployed OMs at two CORKs in 2012 in the northeast pacific at sites 857D and 1025C. The CORKs were visited in 2013 by a vessel of opportunity to download data and were put into sleep mode. The CORKs were revisited in 2014, woken up and successfully interrogated for data. ALVIN retrieved the CORK-OMs for corrosion, biofouling and battery performance assessment. We also performed tests of a next

  2. Characterization of optical communication in a leader-follower unmanned underwater vehicle formation

    NASA Astrophysics Data System (ADS)

    Eren, Firat; Pe'eri, Shachak; Thein, May-Win

    2013-06-01

    As part of the research to development an optical communication design of a leader-follower formation between unmanned underwater vehicles (UUVs), this paper presents light field characterization and design configuration of the hardware required to allow the use of distance detection between UUVs. The study specifically is targeting communication between remotely operated vehicles (ROVs). As an initial step in this study, the light field produced from a light source mounted on the leader UUV was empirically characterized and modeled. Based on the light field measurements, a photo-detector array for the follower UUV was designed. Evaluation of the communication algorithms to monitor the UUV's motion was conducted through underwater experiments in the Ocean Engineering Laboratory at the University of New Hampshire. The optimal spectral range was determined based on the calculation of the diffuse attenuation coefficients by using two different light sources and a spectrometer. The range between the leader and the follower vehicles for a specific water type was determined. In addition, the array design and the communication algorithms were modified according to the results from the light field.

  3. Quantum Limits of Space-to-Ground Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, H.; Dolinar, S.

    2012-01-01

    For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

  4. AlGaAs phased array laser for optical communications

    NASA Technical Reports Server (NTRS)

    Carlson, N. W.

    1989-01-01

    Phased locked arrays of multiple AlGaAs diode laser emitters were investigated both in edge emitting and surface emitting configurations. CSP edge emitter structures, coupled by either evanescent waves or Y-guides, could not achieve the required powers (greater than or similar to 500 mW) while maintaining a diffraction limited, single lobed output beam. Indeed, although the diffraction limit was achieved in this type of device, it was at low powers and in the double lobed radiation pattern characteristic of out-of-phase coupling. Grating surface emitting (GSE) arrays were, therefore, investigated with more promising results. The incorporation of second order gratings in distribute Bragg reflector (DBR) structures allows surface emission, and can be configured to allow injection locking and lateral coupling to populate 2-D arrays that should be able to reach power levels commensurate with the needs of high performance, free space optical communications levels. Also, a new amplitude modulation scheme was developed for GSE array operation.

  5. Sequence Detection for PPM Optical Communication With ISI

    NASA Technical Reports Server (NTRS)

    Moision, Bruce; Srinivasan, Meera; Lee, Clement

    2006-01-01

    A method of sequence detection has been proposed to mitigate the effects of inter-slot interference and inter-symbol interference (both denoted ISI) in the reception of M-ary pulse-position modulation (PPM) optical signals. The method would make it possible to reduce the error rate for a given slot duration, to use a shorter slot duration (and, hence, to communicate at a higher rate) without exceeding a given error rate, or to use a lower-bandwidth (and, hence, less-expensive) receiver to receive a signal of a given slot width without exceeding a given error rate. In M-ary PPM, a symbol period is divided into M time slots, each of duration T(sub s), and a symbol consists of a binary sequence ones and zeros represented by pulses or the absence of pulses, respectively, in the time slots. At the transmitter, the bit stream is used to modulate a laser, the output of which is constant (either full power or zero power, representing 1 or 0, respectively) during each time slot. However, the signal becomes attenuated (signal photons are lost) in propagation from the transmitter to the receiver and noise enters at the receiver, complicating the problem of determining the timing of the symbol periods and slots and identifying the symbols.

  6. Near Earth Architectural Options for a Future Deep Space Optical Communications Network

    NASA Technical Reports Server (NTRS)

    Edwards, B. L.; Liebrecht, P. E.; Fitzgerald, R. J.

    2004-01-01

    In the near future the National Aeronautics and Space Administration anticipates a significant increase in demand for long-haul communications services from deep space to Earth. Distances will range from 0.1 to 40 AU, with data rate requirements in the 1's to 1000's of Mbits/second. The near term demand is driven by NASA's Space Science Enterprise which wishes to deploy more capable instruments onboard spacecraft and increase the number of deep space missions. The long term demand is driven by missions with extreme communications challenges such as very high data rates from the outer planets, supporting sub-surface exploration, or supporting NASA's Human Exploration and Development of Space Enterprise beyond Earth orbit. Laser communications is a revolutionary communications technology that will dramatically increase NASA's ability to transmit information across the solar system. Lasercom sends information using beams of light and optical elements, such as telescopes and optical amplifiers, rather than RF signals, amplifiers, and antennas. This paper provides an overview of different network options at Earth to meet NASA's deep space lasercom requirements. It is based mainly on work done for the Mars Laser Communications Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It reports preliminary conclusions from the Mars Lasercom Study conducted at MIT/LL and on additional work done for the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telesat Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

  7. Earth-Image Tracking in the IR for Deep Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Chen, Yinging; Lee, Shinhak; Ortiz, Gerard G.

    2005-01-01

    Sub-microradian level laser beam pointing to an Earth-based receiver is required for deep space optical communications. This requires a beacon emanated from Earth towards the spacecraft. The beacon could be a laser or reflected sunlight from Earth. Earth image tracking in the visible is hampered by significant albedo variations and/or crescent Earth image yielding large central errors. Here, we report results of Earth-image tracking in the infrared (8 to 13 micron) region of the spectrum with the aim of substantially alleviating the two challenges mentioned earlier.

  8. Free-space optical communication satellite networks-vibration effects and possible solutions

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi; Kopeika, Norman S.

    1997-07-01

    A number of serious consortiums develop satellite communication networks. The objective of these communication projects is to service personal communication users almost everywhere on earth. The inter satellite links in those project use microwave radiation as the carrier. Free space optical communication between satellites networked together can make possible high speed communications between different places on earth. The advantages of an optical communication system instead of a microwave communication system in free space are: (1) smaller size and weight, (2) less transmitter power, (3) larger bandwidth, (4) higher immunity to interference, and (5) smaller transmitter beam divergence. The use of optical radiation as a carrier between the satellites creates very narrow beam divergence angles. Due to the narrow beam divergence angle and the large distance between the satellites the pointing from one satellite to another is complicated. The problem is more complicated due to vibration of the pointing system caused by two stochastic fundamental mechanisms (1) tracking noise created by the electrooptic tracker and (2) vibrations created by internal and external mechanical mechanisms. The vibrations displace the transmitted beam in the receiver plane. Such movement of the transmitted beam in the receiver plane decreases the average received signal which decreases increases the bit error rate. In this paper we review: (1) the present status of satellite networks, (2) developing efforts of optical satellite communication around the world, (3) performance results of vibration effects on different kinds of optical communication satellite networks and (4) seven approaches to overcome the problems caused by transmitter pointing vibration.

  9. An inter-mountain optical-communications link experiment in Spain

    NASA Astrophysics Data System (ADS)

    Ruiz, D.; Czichy, R.; Freudenthaler, V.; Bara, J.; Comeron, A.

    In support of the ESA's SILEX optical-communications project, a first evaluation of the suitability of the Canary Islands (Spain) for an optical communications test range has been conducted. The study of the geographical and climatic characteristics of the test site and the theoretical analysis of its atmospheric conditions have shown that the Canary Islands are a suitable site for performing terrestrial experiments for the characterization of laser communications systems for space applications. The feasibility of establishing an optical space-to-ground link with an optical ground station at this site has been demonstrated. Moreover, the site seems promising as a far-field test range for future optical free-space communications systems.

  10. Underwater optical wireless communications: depth dependent variations in attenuation.

    PubMed

    Johnson, Laura J; Green, Roger J; Leeson, Mark S

    2013-11-20

    Depth variations in the attenuation coefficient for light in the ocean were calculated using a one-parameter model based on the chlorophyll-a concentration C(c) and experimentally-determined Gaussian chlorophyll-depth profiles. The depth profiles were related to surface chlorophyll levels for the range 0-4  mg/m², representing clear, open ocean. The depth where C(c) became negligible was calculated to be shallower for places of high surface chlorophyll; 111.5 m for surface chlorophyll 0.8communication links, calculated to be 0.0092  m⁻¹ at a wavelength of 430 nm. By combining this with satellite surface-chlorophyll data, it is possible to quantify the attenuation between any two locations in the ocean, with applications for low-noise or secure underwater communications and vertical links from the ocean surface. PMID:24513735

  11. Peculiarities in construction of optical receivers for digital fiber-optic communication lines

    NASA Astrophysics Data System (ADS)

    Pismerov, O. B.; Derevyannykh, I. M.

    1984-05-01

    Optical receivers for fiber-optic communication lines in a radial network require booster amplifiers for signals which usually do not exceed 5 mV after preamplification. They are ac amplifiers with a clamped output level, automatic gain control, and a peak detector. This simple version is adequate for unidirectional lines with few branches. A booster amplifier for operation in a multistation with with bidirectional lines, busbar structure, and time division of channels requires a high speed peak detector which must be cleared after passage of the message carrying pulse packet. This is done by means of a precisely matched transistor pair able to generate a clearing pulse over a wide range of temperatures. For linear conversion (d/dt) of the preamplifier output signal it is expedient to replace the automatic gain control with a symmetric limiter amplifier followed by a set of pulse rise time and pulse fall time discriminators in parallel, which respectively feed the R input and the S input of a trigger, The sensitivity and the dynamic range of such optical receivers before somewhat worse as their complexity increases.

  12. Optical Communications Telescope Laboratory (OCTL) Support of Space to Ground Link Demonstrations

    NASA Technical Reports Server (NTRS)

    Biswas, Abhijit; Kovalik, Joseph M.; Wright, Malcolm W.; Roberts, William T.

    2014-01-01

    The NASA/JPL Optical Communication Telescope Laboratory (OCTL) was built for dedicated research and development toward supporting free-space laser communications from space. Recently, the OCTL telescope was used to support the Lunar Laser Communication Demonstration (LLCD) from the Lunar Atmospheric Dust Environment Explorer (LADEE) spacecraft and is planned for use with the upcoming Optical Payload for Lasercomm Science (OPALS) demonstration from the International Space Station (ISS). The use of OCTL to support these demonstrations is discussed in this report. The discussion will feed forward to ongoing and future space-to-ground laser communications as it advances toward becoming an operational capability.

  13. Knowledge-based optical system design

    NASA Astrophysics Data System (ADS)

    Nouri, Taoufik

    1992-03-01

    This work is a new approach for the design of start optical systems and represents a new contribution of artificial intelligence techniques in the optical design field. A knowledge-based optical-systems design (KBOSD), based on artificial intelligence algorithms, first order logic, knowledge representation, rules, and heuristics on lens design, is realized. This KBOSD is equipped with optical knowledge in the domain of centered dioptrical optical systems used at low aperture and small field angles. It generates centered dioptrical, on-axis and low-aperture optical systems, which are used as start systems for the subsequent optimization by existing lens design programs. This KBOSD produces monochromatic or polychromatic optical systems, such as singlet lens, doublet lens, triplet lens, reversed singlet lens, reversed doublet lens, reversed triplet lens, and telescopes. In the design of optical systems, the KBOSD takes into account many user constraints such as cost, resistance of the optical material (glass) to chemical, thermal, and mechanical effects, as well as the optical quality such as minimal aberrations and chromatic aberrations corrections. This KBOSD is developed in the programming language Prolog and has knowledge on optical design principles and optical properties. It is composed of more than 3000 clauses. Inference engine and interconnections in the cognitive world of optical systems are described. The system uses neither a lens library nor a lens data base; it is completely based on optical design knowledge.

  14. Research on diversity receive technology for wireless optical communication using PPM in weak turbulence atmosphere channel

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Zhang, Guo-an

    2014-09-01

    In order to mitigate atmospheric turbulence, the free space optical (FSO) system model with spatial diversity is analyzed based on intensity detection pulse position modulation (PPM) in the weak turbulence atmosphere. The slot error rate (SER) calculating formula of the system without diversity is derived under pulse position modulation firstly. Then as a benchmark, independent of identical distribution, the average slot error rates of the three linear combining technologies, which are the maximal ratio combining (MRC), equal gain combining (EGC) and selection combining (SelC), are compared. Simulation results show that the performance of system is the best improved by MRC, followed by EGC, and is poor by SelC, but SelC is simpler and more convenient. Spatial diversity is efficient to improve the performance and has strong ability on resistance to atmospheric channel decline. The above scheme is more suitable for optical wireless communication systems.

  15. Message extraction mechanism in optical chaos communications using injection-locked semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Murakami, Atsushi; Shore, K. Alan

    2006-09-01

    In this paper, we employ a simple theory based on driven damped oscillators to clarify the physical basis for message extraction in optical chaos communications using injection-locked semiconductor lasers. The receiver laser is optically driven by injection from the transmitter laser. We have numerically investigated the response characteristics of the receiver when it is driven by periodic (message) and chaotic (carrier) signals. It is thereby revealed that the response of the receiver laser in the two cases is quite different. For the periodic drive, the receiver exhibits a response depending on the signal frequency, while the chaotic drive provides a frequency-independent synchronous response to the receiver laser. CPF can be clearly understood in the difference between the periodic and chaotic drives. Message extraction using CPF is also examined, and the validity of our theoretical explanation for the physical mechanism underlying CPF is thus verified.

  16. Analysis of the stability and optimizing operation of the single-side-band modulator based on re-circulating frequency shifter used for the T-bit/s optical communication transmission.

    PubMed

    Li, Jianping; Li, Xuan; Zhang, Xiaoguang; Tian, Feng; Xi, Lixia

    2010-08-16

    The stability of single-sideband (SSB) modulator based recirculating frequency shifter (RFS) is analyzed theoretically. The optimum radio frequency (RF) drive peak-to-peak voltage used to drive the modulator is studied with considering the amplified spontaneous emission (ASE) noise of optical amplifier and crosstalk so as to obtain a maximum overall effective optical signal to noise ratio (OSNR) which is defined to quantify the quality of generated tones. Small desired tones number and lower RF peak-to-peak voltage can reduce the crosstalk effectively. While the trade-off should be considered since the larger desired tones number it is, the higher optimum drive voltage should be used when the SSB-based RFS reached the maximum OSNR. The theoretical results show that the optimum operation condition is helpful to improve the performance of RFS which can be a good application for the T-bit/s optical transmission in practice. PMID:20721146

  17. Fiber optic-based regenerable biosensor

    DOEpatents

    Sepaniak, Michael J.; Vo-Dinh, Tuan

    1993-01-01

    A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

  18. Forecasting of Optical Turbulence in Support of Realtime Optical Imaging and Communication Systems

    NASA Astrophysics Data System (ADS)

    Alliss, R.; Felton, B.

    2012-09-01

    Optical turbulence (OT) acts to distort light in the atmosphere, degrading imagery from large astronomical and imaging telescopes and possibly reducing data quality of free space optical communication (FSOC) links. Some of the degradation due to optical turbulence can be corrected by adaptive optics. However, the severity of optical turbulence, and thus the amount of correction required, is largely dependent upon the turbulence at the location of interest. In addition, clouds, precipitation, and inhomogeneities in atmospheric temperature and moisture all have the potential to disrupt imaging and communications through the atmosphere. However, there are strategies that can be employed to mitigate the atmospheric impacts. These strategies require an accurate characterization of the atmosphere through which the communications links travel. To date these strategies have been to climatological characterize OT and its properties. Recently efforts have been developed to employ a realtime forecasting system which provides planners useful information for maintaining links and link budgets. The strength of OT is characterized by the refractive index structure function Cn2, which in turn is used to calculate atmospheric seeing parameters. Atmospheric measurements provided by local instrumentation are valuable for link characterization, but provide an incomplete picture of the atmosphere. While attempts have been made to characterize Cn2 using empirical models, Cn2 can be calculated more directly from Numerical Weather Prediction (NWP) simulations using pressure, temperature, thermal stability, vertical wind shear, turbulent Prandtl number, and turbulence kinetic energy (TKE). During realtime FSOC demonstrations, in situ measurements are supplemented with NWP simulations, which provide near realtime characterizations and forecasts of the Cn2, the Fried Coherence Length (ro), and time-varying, three-dimensional characterizations of the atmosphere. The three dimensional Weather

  19. The network and transmission of based on the principle of laser multipoint communication

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Liu, Xianzhu; Jiang, Huilin; Hu, Yuan; Jiang, Lun

    2014-11-01

    Space laser communication is the perfectly choose to the earth integrated information backbone network in the future. This paper introduces the structure of the earth integrated information network that is a large capacity integrated high-speed broadband information network, a variety of communications platforms were densely interconnected together, such as the land, sea, air and deep air users or aircraft, the technologies of the intelligent high-speed processing, switching and routing were adopt. According to the principle of maximum effective comprehensive utilization of information resources, get accurately information, fast processing and efficient transmission through inter-satellite, satellite earth, sky and ground station and other links. Namely it will be a space-based, air-based and ground-based integrated information network. It will be started from the trends of laser communication. The current situation of laser multi-point communications were expounded, the transmission scheme of the dynamic multi-point between wireless laser communication n network has been carefully studied, a variety of laser communication network transmission schemes the corresponding characteristics and scope described in detail , described the optical multiplexer machine that based on the multiport form of communication is applied to relay backbone link; the optical multiplexer-based on the form of the segmentation receiver field of view is applied to small angle link, the optical multiplexer-based form of three concentric spheres structure is applied to short distances, motorized occasions, and the multi-point stitching structure based on the rotation paraboloid is applied to inter-satellite communications in detail. The multi-point laser communication terminal apparatus consist of the transmitting and receiving antenna, a relay optical system, the spectroscopic system, communication system and communication receiver transmitter system. The communication forms of optical

  20. Secure direct communication based on secret transmitting order of particles

    SciTech Connect

    Zhu Aidong; Zhang Shou; Xia Yan; Fan Qiubo

    2006-02-15

    We propose the schemes of quantum secure direct communication based on a secret transmitting order of particles. In these protocols, the secret transmitting order of particles ensures the security of communication, and no secret messages are leaked even if the communication is interrupted for security. This strategy of security for communication is also generalized to a quantum dialogue. It not only ensures the unconditional security but also improves the efficiency of communication.

  1. A near-earth optical communications terminal with a corevolving planetary sun shield

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1987-01-01

    The umbra of a planet may serve as a sun shield for a space based optical communications terminal or for a space based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter.

  2. A near-earth optical communications terminal with a corevolving planetary sun shield

    NASA Technical Reports Server (NTRS)

    Kerr, E. L.

    1989-01-01

    The umbra of a planet may serve as a sun shield for a space-based optical communications terminal or for a space-based astronomical observatory. An orbit that keeps the terminal or observatory within the umbra is desirable. There is a corevolution point behind every planet. A small body stabilized at the planet corevolution point will revolve about the sun at the same angular velocity as the planet, always keeping the planet between itself and the sun. This corevolution point is within the umbra of Mars but beyond the end of the umbra for Mercury, Venus, and earth. The Mars corevolution point is an ideal location for an astronomical observatory. There, Mars obstruct less than 0.00024 percent of the sky at any time, and it shades the observatory completely from the sun. At the earth corevolution point, between 51 and 84 percent of the solar disk area is blocked, as is up to 92 percent of the sunlight. This provides a reduction from 3 dB to 11 dB in sunlight that could interfere with optical communications if scattered directly into the detectors. The variations is caused by revolution of the earth about the earth-moon barycenter.

  3. All-optical microwave signal processing based on optical phase modulation

    NASA Astrophysics Data System (ADS)

    Zeng, Fei

    implemented by use of commercially available devices without increasing significantly the system complexity compared to IM-based systems. More importantly, the PM-IM conversions bring a number of very interesting features which would be used to implement different signal processing functionalities. First, the PM-IM conversion plus direct detection has a frequency response with a notch at the dc, this feature can be used to achieve all-optical microwave bandpass filtering. Second, in the PM-IM conversion based on frequency discrimination, the polarity of the detected electrical signal can be easily reversed by simply tuning the optical wavelength, which provides the possibility to achieve bipolar operation, a feature highly desirable and extremely important in all-optical microwave signal processing. In this thesis, the use of the PM-IM conversion features for all-optical signal processing is investigated. Specifically, (1) We propose and demonstrate three different filter architectures for all-optical microwave bandpass filtering. (2) We propose and demonstrate, for the first time, an all-optical microwave signal processor that can realize all-optical mixing and filtering simultaneously. (3) We propose and demonstrate a scheme to implement unipolar-bipolar phase-time encoding/decoding for optical CDMA. (4) UWB pulses are usually generated in the electrical domain for short-range high-data rate wireless communications. To extend its coverage, UWB signal distributed over optical fiber is a topic of interest recently. In the thesis, we propose and demonstrate two approaches to generating and distributing UWB pulses in the optical domain.

  4. Performance analysis of OOK receiver with a GSM laser in space to ground optical communication link

    NASA Astrophysics Data System (ADS)

    Li, Mengnan; Tan, Liying; Ma, Jing; Yu, Siyuan; Wu, Jiajie; Wang, Qi

    2015-09-01

    In practice, due to reasons related to the characteristics of the laser device and the inevitable error of the processing technique, a laser source emitted from a communication terminal is represented by the Gaussian Schell model (GSM). In a space to ground optical communication link, the incident optical intensity at the receiver aperture is affected by the source coherence parameter and the zenith angle. With full consideration of both the average optical intensity and scintillation, the statistical distribution of the optical intensity and the average bit error rate (BER) are obtained with different zenith angle and source coherence parameter. The effect of the source coherence parameter on the performance of an on-off-keying (OOK) receiver is systematically analyzed. The results indicate that the performance degrades seriously with increasing source coherence parameter or zenith angle. The hope of this work is to improve the redundancy design of the optical communication receiver system.

  5. Airborne Wireless Optical Communication System in Low Altitude Using an Unmanned Aerial Vehicle and LEDs

    NASA Astrophysics Data System (ADS)

    Kong, Meiwei; Tong, Zheng; Yu, Xiangyu; Song, Yuhang; Lin, Aobo; Xu, Jing

    2016-02-01

    In this paper, we demonstrate the feasibility of airborne wireless optical communication system using an unmanned aerial vehicle and LEDs. Monte Carlo simulation method is used to evaluate the performance of the communication channel. Considering OOK modulation, we illustrate how the BER performance is affected by the link distance, the divergence angel and the deflection angel of the light source.

  6. Development of a 1-m Class Telescope at TMF to Support Optical Communications Demonstrations

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Sandusky, J.

    1998-01-01

    With the impetus towards high data rate communications in inter-satellite and space-to-ground links, the small size, low-mass, and low-power consumption of optical communications is seen as a viable alternative to radio frequency links.

  7. A plan for the development and demonstration of optical communications for deep space

    NASA Technical Reports Server (NTRS)

    Lesh, James R.; Deutsch, Leslie J.; Weber, William J.

    1991-01-01

    A development history, current status, and prospective development account are given for deep-space optical communications, giving attention to overall systems-related activities and to the generic technology developments required for their implementation. An account is given of the progression envisioned from laboratory subsystems demonstrations to the full-scale flight experiment for the Mars Communications Relay Orbiter missions.

  8. Secure communication based on spatiotemporal chaos

    NASA Astrophysics Data System (ADS)

    Ren, Hai-Peng; Bai, Chao

    2015-08-01

    In this paper, we propose a novel approach to secure communication based on spatiotemporal chaos. At the transmitter end, the state variables of the coupled map lattice system are divided into two groups: one is used as the key to encrypt the plaintext in the N-shift encryption function, and the other is used to mix with the output of the N-shift function to further confuse the information to transmit. At the receiver end, the receiver lattices are driven by the received signal to synchronize with the transmitter lattices and an inverse procedure of the encoding is conducted to decode the information. Numerical simulation and experiment based on the TI TMS320C6713 Digital Signal Processor (DSP) show the feasibility and the validity of the proposed scheme. Project supported by the National Natural Science Foundation of China (Grant No. 61172070) and the Funds from the Science and Technology Innovation Team of Shaanxi Province, China (Grant No. 2013CKT-04).

  9. Fiber optics systems mode analysis based on Dirac equation

    NASA Astrophysics Data System (ADS)

    Bagmanov, Valeriy K.; Sultanov, Albert K.

    2016-03-01

    In this paper we introduce a novel approach for analysis of the information transmission process in mode-division-multiplexed (MDM) optical fiber communications. This approach is based on the representation of Maxwell's equations in the form of quantum-mechanical Schrödinger and Dirac equations. This representation allows application of the well-developed quantum electrodynamics formalism for the case of classical EM fields and reveals key properties of the optical fiber mode distribution in MDM systems following from the total angular momentum conservation law. We demonstrate the need of using coupled mode compositions instead of separate eigenmodes for realization of MDM communications based on angular momentum transfer. Such coupled modal compositions obey the law of total angular momentum conservation within spatial transformation and allow information transmission.

  10. Digital signal processing techniques for coherent optical communication

    NASA Astrophysics Data System (ADS)

    Goldfarb, Gilad

    deterministic effects pose for long-haul optical data transmission. Experimental results which demonstrate the possibility to digitally mitigate both dispersion and nonlinearity are presented. Impairment compensation is achieved using backward propagation by implementing the split-step method. Efficient realizations of the dispersion compensation operator used in this implementation are considered. Infinite-impulse response and wavelet-based filtering are both investigated as a means to reduce the required computational load associated with signal backward-propagation. Possible future research directions conclude this dissertation.

  11. MEMS-Based Communications Systems for Space-Based Applications

    NASA Technical Reports Server (NTRS)

    DeLosSantos, Hector J.; Brunner, Robert A.; Lam, Juan F.; Hackett, Le Roy H.; Lohr, Ross F., Jr.; Larson, Lawrence E.; Loo, Robert Y.; Matloubian, Mehran; Tangonan, Gregory L.

    1995-01-01

    As user demand for higher capacity and flexibility in communications satellites increases, new ways to cope with the inherent limitations posed by the prohibitive mass and power consumption, needed to satisfy those requirements, are under investigation. Recent studies suggest that while new satellite architectures are necessary to enable multi-user, multi-data rate, multi-location satellite links, these new architectures will inevitably increase power consumption, and in turn, spacecraft mass, to such an extent that their successful implementation will demand novel lightweight/low power hardware approaches. In this paper, following a brief introduction to the fundamentals of communications satellites, we address the impact of micro-electro-mechanical systems (MEMS) technology, in particular micro-electro-mechanical (MEM) switches to mitigate the above mentioned problems and show that low-loss/wide bandwidth MEM switches will go a long way towards enabling higher capacity and flexibility space-based communications systems.

  12. Community detection based on network communicability

    NASA Astrophysics Data System (ADS)

    Estrada, Ernesto

    2011-03-01

    We propose a new method for detecting communities based on the concept of communicability between nodes in a complex network. This method, designated as N-ComBa K-means, uses a normalized version of the adjacency matrix to build the communicability matrix and then applies K-means clustering to find the communities in a graph. We analyze how this method performs for some pathological cases found in the analysis of the detection limit of communities and propose some possible solutions on the basis of the analysis of the ratio of local to global densities in graphs. We use four different quality criteria for detecting the best clustering and compare the new approach with the Girvan-Newman algorithm for the analysis of two "classical" networks: karate club and bottlenose dolphins. Finally, we analyze the more challenging case of homogeneous networks with community structure, for which the Girvan-Newman completely fails in detecting any clustering. The N-ComBa K-means approach performs very well in these situations and we applied it to detect the community structure in an international trade network of miscellaneous manufactures of metal having these characteristics. Some final remarks about the general philosophy of community detection are also discussed.

  13. Digital, Satellite-Based Aeronautical Communication

    NASA Technical Reports Server (NTRS)

    Davarian, F.

    1989-01-01

    Satellite system relays communication between aircraft and stations on ground. System offers better coverage with direct communication between air and ground, costs less and makes possible new communication services. Carries both voice and data. Because many data exchanged between aircraft and ground contain safety-related information, probability of bit errors essential.

  14. Fiber-Optic Communication Links Suitable for On-Board Use in Modern Aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, Hung; Ngo, Duc; Alam, Mohammad F.; Atiquzzaman, Mohammed; Sluse, James; Slaveski, Filip

    2004-01-01

    The role of the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Centers has been focused mainly on the improvement of air transportation safety, with particular emphasis on air transportation communication systems in on-board aircraft. The conventional solutions for digital optical communications systems specifically designed for local/metro area networks are, unfortunately, not capable of transporting the microwave and millimeter RF signals used in avionics systems. Optical networks capable of transporting RF signals are substantially different from the standard digital optical communications systems. The objective of this paper is to identify a number of different communication link architectures for RF/fiber optic transmission using a single backbone fiber for carrying VHF and UHF RF signals in the aircraft. To support these architectures, two approaches derived from both hybrid RF-optical and all-optical processing methodologies are discussed with single and multiple antennas for explicitly transporting VHF and UHF signals, while the relative merits and demerits of each architecture are also addressed. Furthermore, the experimental results of wavelength division multiplexing (WDM) link architecture from our test-bed platform, configured for aircraft environment to support simultaneous transmission of multiple RF signals over a single optical fiber, exhibit no appreciable signal degradation at wavelengths of both 1330 and 1550 nm, respectively. Our measurements of signal to noise ratio carried out for the transmission of FM and AM analog modulated signals at these wavelengths indicate that WDM is a fiber optic technology which is potentially suitable for avionics applications.

  15. Dual-polarization OFDM-OQAM for communications over optical fibers with coherent detection.

    PubMed

    Horlin, François; Fickers, Jessica; Emplit, Philippe; Bourdoux, André; Louveaux, Jérome

    2013-03-11

    In order to improve the spectral efficiency of coherent optical communication systems, it has recently been proposed to make use of the orthogonal frequency-division multiplexing offset quadrature amplitude modulation (OFDM-OQAM). Multiple optical channels spaced in the frequency domain by the symbol rate can be transmitted orthogonally, even if each channel overlaps significantly in frequency with its two adjacent channels. The solutions proposed until now in the literature unfortunately only address a single polarization communication, and therefore do not benefit from the capacity gain reached when two polarizations are used to transmit independent information signals. The aim of the present paper is to propose a receiver architecture that can decouple the two polarizations. We build an equalizer per channel at twice the symbol rate and optimize it based on the minimum mean square error (MMSE) criterion. We demonstrate the efficiency of the resulting system compared to the Nyquist wavelength-division multiplexing (N-WDM) system both in terms of performance and complexity. We also assess the system sensitivity to transmit synchronization errors and show that system can even work under significant synchronization errors. PMID:23482211

  16. Optical scintillations and fade statistics for a satellite-communication system

    NASA Astrophysics Data System (ADS)

    Andrews, L. C.; Phillips, R. L.

    1995-11-01

    Estimates of the scintillation index, fractional fade time, expected number of fades, and mean duration of fade time associated with a propagating Gaussian-beam wave are developed for uplink and downlink laser satellite-communication channels. Estimates for the spot size of the beam at the satellite or the ground or airborne receiver are also provided. Weak-fluctuation theory based on the log-normal model is applicable for intensity fluctuations near the optical axis of the beam provided that the zenith angle is not too large, generally not exceeding 60 degrees. However, there is an increase in scintillations that occurs with increasing pointing error at any zenith angle, particularly for uplink channels. Large off-axis scintillations are of particular significance because they imply that small pointing errors can cause serious degradation in the communication-channel reliability. Off-axis scintillations increase more rapidly for larger-diameter beams and, in some cases, can lead to a radial saturation effect for pointing errors less than 1 =B5rad off the optical beam axis.

  17. Optical scintillations and fade statistics for a satellite-communication system.

    PubMed

    Andrews, L C; Phillips, R L; Yu, P T

    1995-11-20

    Estimates of the scintillation index, fractional fade time, expected number of fades, and mean duration of fade time associated with a propagating Gaussian-beam wave are developed for uplink and downlink laser satellite-communication channels. Estimates for the spot size of the beam at the satellite or the ground or airborne receiver are also provided. Weak-fluctuation theory based on the log-normal model is applicable for intensity fluctuations near the optical axis of the beam provided that the zenith angle is not too large, generally not exceeding 60°. However, there is an increase in scintillations that occurs with increasing pointing error at any zenith angle, particularly for uplink channels. Large off-axis scintillations are of particular significance because they imply that small pointing errors can cause serious degradation in the communication-channel reliability. Off-axis scintillations increase more rapidly for larger-diameter beams and, in some cases, can lead to a radial saturation effect for pointing errors less than 1 µrad off the optical beam axis. PMID:21060656

  18. RF-modulated pulsed fiber optic lidar transmitter for improved underwater imaging and communications

    NASA Astrophysics Data System (ADS)

    Kimpel, F.; Chen, Y.; Fouron, J.-L.; Akbulut, M.; Engin, D.; Gupta, S.

    2011-03-01

    We present results on the design, development and initial testing of a fiber-optic based RF-modulated lidar transmitter operating at 532nm, for underwater imaging application in littoral waters. The design implementation is based on using state-of-the-art high-speed FPGAs, thereby producing optical waveforms with arbitrary digital-RF-modulated pulse patterns with carrier frequencies >= 3GHz, with a repetition rate of 0.5-1MHz, and with average powers >=5W (at 532nm). Use of RF-modulated bursts above 500MHz, instead of single optical pulse lidar detection, reduces the effect of volumetric backscatter for underwater imaging application, leading to an improved signal-to-noise-ratio (SNR) and contrast, for a given range. Initial underwater target detection tests conducted at Patuxent River Naval Air Station, MD, in a large water-tank facility, validates the advantages of this hybrid-lidar-radar (HLR) approach for improved underwater imaging, over a wide range of turbidity levels and both white and black targets. The compact, robust and power-efficient fiber laser architecture lends very well to lidar sensor integration on unmanned-underwater-vehicle (UUV) platforms. HLR transmitters can also provide similar advantages in active-sensing situations dominated by continuous backscatter, e.g. underwater communications, imaging through smoke and fire environment, rotor-craft landing in degraded visual environment, and pointing-tracking of active-EO sensors through fog.

  19. Multiplexing OAM states in an optical fiber: Increase bandwidth of quantum communication and QKD applications

    NASA Astrophysics Data System (ADS)

    Gupta, Manish Kumar; Dowling, Jonathan P.

    2015-05-01

    We propose a noble method for multiplexing OAM states to increase bandwidth of communication in a birefringent single-mode optical fiber for quantum communication and QKD applications by minimizing the decoherence. We analytically derive and show that the rate of decoherence for OAM state in a birefringent optical fiber is proportional to l2. We also show numerically that decoherence can be minimized with CPMG pulse sequence to preserve the state with > 90 % fidelity for smaller values of l to allow for high-bandwidth communication. Louisiana State University, Baton Rouge, Louisiana 70803, USA.

  20. A Plan for the Development and Demonstration of Optical Communications for Deep Space

    NASA Technical Reports Server (NTRS)

    Lesh, J. R.; Deutsch, L. J.; Weber, W. J.

    1990-01-01

    In this article, an overall plan for the development and demonstration of optical communications for deep-space applications is presented. The current state of the technology for optical communications is presented. Then, the development and demonstration plan is presented in two parts: the overall major systems activities, followed by the generic technology developments that will enable them. The plan covers the path from laboratory subsystems demonstrations out to a full-scale flight experiment system for the proposed Mars Communications Relay Orbiter mission.

  1. NASA/GSFC program in direct detection optical communications for intersatellite links

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, M.; Bruno, R.

    1989-01-01

    NASA-Goddard has undertaken the development of direct-detection optical communications for space applications at the Gbps data rate channel capability level. The primary challenges to optical communications designers lie in the development of reliable optical power sources, as well as of high performance pointing/acquisition/tracking systems required by the narrow widths of the transmitted optical beams. GaAlAs diodes and their arrays are currently the most attractive technology for optical transmitters; pioneering work has also been conducted on dichroic and grating techniques for combining the power of several laser diodes. Attention is given to the performance obtained for an optical link acquisition and submicroradian tracking/pointing system.

  2. Communication

    NASA Technical Reports Server (NTRS)

    Griner, James

    2010-01-01

    NASA s communication work for the UAS Command and Control area will build upon work currently being conducted under NASA Recovery Act funds. Communication portions of UAS NextGen ConOps, Stateof- the-Art assessment, and Gap Analysis. Preliminary simulations for UAS CNPC link scalability assessment. Surrogate UAS aircraft upgrades. This work will also leverage FY10 in-guide funding for communication link model development. UAS are currently managed through exceptions and are operating using DoD frequencies for line-of-sight (LOS) and satellite-based communications links, low-power LOS links in amateur bands, or unlicensed Instrument/Scientific/Medical (ISM) frequencies. None of these frequency bands are designated for Safety and Regularity of Flight. No radio-frequency (RF) spectrum has been allocated by the International Telecommunications Union (ITU) specifically for UAS command and control links, for either LOS or Beyond LOS (BLOS) communication.

  3. Optical networking by DLP-based switched blazed grating

    NASA Astrophysics Data System (ADS)

    Lin, Hoang Yan; Chung, Shuang-Chao

    2005-02-01

    All-optical modules are devices which process and transport optical signals without transforming to electronic signals. They get more attention as the optical communication network becomes more and more complicated. Among them, OADM (optical add drop module) is one of the most important devices in the optical DWDM (dense wavelength division multiplex) network. It plays the role of a node in network to upload/download signals or to route signals for optical performance monitoring. Applied broadly in projection display systems, DLP (Digital Light Processing) from Texas Instruments turns out to be a versatile device for optical signal processing. The working principle of DLP is based on so called switched-blazed-grating. Part of its micro-mirror array can be formed as a dynamic blazed grating with a period of 14 μm by tilting the micro-mirrors at an angle of +/-12 degrees. It is expected to function as either a switch or an attenuator by directing total or part of the incident light between the 2nd and -2nd diffraction orders. In this paper, we investigate the optical characteristics of a switched-blazed-grating, its application as a re-configurable OADM, and the performance of such a device. Ray tracing and optical analysis of the OADM are made by using package software ASAP from Breault Research Organization. In conclusion, as a mature and reliable MEMS device, DLP-based switched-blazed-grating provides a very versatile platform for digital optical signal processing and can be used as a dynamic optical-networking device with good performance.

  4. Progress in Design and Construction of the Optical Communications Laser Laboratory

    NASA Technical Reports Server (NTRS)

    Wilson, K. E.; Britcliffe, M.; Golshan, N.

    1999-01-01

    The deployment of advanced hyperspectral imaging and other Earth sensing instruments on board Earth observing satellites is driving the demand for high-data-rate communications. Optical communications meet the required data rates with small, low mass, and low-power communications packages. JPL, as NASA's lead center in optical communications, plans to construct a 1-m Optical Communications Telescope Laboratory (OCTL) at its Table Mountain Facility (TMF) complex in the San Gabriel Mountains of Southern California. The design of the building has been completed, and the construction contractor has been selected. Ground breaking is expected to start at the beginning of the 1999 TMF construction season. A request for proposal (RFP) has been issued for the procurement of the telescope system. Prior to letting the RFP we conducted a request for information with industry for the telescope system. Several vendors responded favorably and provided information on key elements of the proposed design. These inputs were considered in developing the final requirements in the RFP. Keywords: Free space optical communications, lasercom, telescopes, ground stations, adaptive optics, astrometry, Table Mountain Facility

  5. SAW based systems for mobile communications satellites

    NASA Technical Reports Server (NTRS)

    Peach, R. C.; Miller, N.; Lee, M.

    1993-01-01

    Modern mobile communications satellites, such as INMARSAT 3, EMS, and ARTEMIS, use advanced onboard processing to make efficient use of the available L-band spectrum. In all of these cases, high performance surface acoustic wave (SAW) devices are used. SAW filters can provide high selectivity (100-200 kHz transition widths), combined with flat amplitude and linear phase characteristics; their simple construction and radiation hardness also makes them especially suitable for space applications. An overview of the architectures used in the above systems, describing the technologies employed, and the use of bandwidth switchable SAW filtering (BSSF) is given. The tradeoffs to be considered when specifying a SAW based system are analyzed, using both theoretical and experimental data. Empirical rules for estimating SAW filter performance are given. Achievable performance is illustrated using data from the INMARSAT 3 engineering model (EM) processors.

  6. Investigation of the MQAM modulation schemes in downlink of space optical communication system

    NASA Astrophysics Data System (ADS)

    Li, Mi; Wang, Ning; Li, Bowen; Zhang, Xuping; Song, Yuejiang; Zhang, Yingjie; Tu, Guojie

    2015-10-01

    Based on weak fluctuation theory, the expression of bit-error rate (BER) of Multiple Quadrature Amplitude Modulation (MQAM) with the consideration of detector noise in the downlink of space communication system is discussed in this paper. According to the expression, the performance of three typical modulation schemes, which are 4QAM, 16QAM, 64QAM, are specially analyzed. It is known that the higher the order of the modulation scheme is, the more bits of information per symbol can carry. However, when the transmission power is 1 W and the receiver diameter Dr is 1 m, the BER is 2.12×10-13 for 4QAM, 5.98×10-8 for 16QAM and 6.22×10-5 for 64QAM, which means that a higher order modulation scheme shows a higher bit-error rate (BER). Thus considering bandwidth efficiency as well as bit error rate, 16QAM is highly recommended in the real space optical communication system. In addition, the relationships between BER and optimum divergence angle, transmitter beam radius, receiving aperture for downlink are also suggested respectively in this paper, which has important reference significance for the design of the ground-to-satellite laser communication system.

  7. Semiconductor-based optical refrigerator

    DOEpatents

    Epstein, Richard I.; Edwards, Bradley C.; Sheik-Bahae, Mansoor

    2002-01-01

    Optical refrigerators using semiconductor material as a cooling medium, with layers of material in close proximity to the cooling medium that carries away heat from the cooling material and preventing radiation trapping. In addition to the use of semiconducting material, the invention can be used with ytterbium-doped glass optical refrigerators.

  8. RF/optical shared aperture for high availability wideband communication RF/FSO links

    DOEpatents

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2015-03-24

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  9. RF/optical shared aperture for high availability wideband communication RF/FSO links

    DOEpatents

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2014-04-29

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  10. Concurrent System Engineering and Risk Reduction for Dual-Band (RF/optical) Spacecraft Communications

    NASA Technical Reports Server (NTRS)

    Fielhauer, Karl, B.; Boone, Bradley, G.; Raible, Daniel, E.

    2012-01-01

    This paper describes a system engineering approach to examining the potential for combining elements of a deep-space RF and optical communications payload, for the purpose of reducing the size, weight and power burden on the spacecraft and the mission. Figures of merit and analytical methodologies are discussed to conduct trade studies, and several potential technology integration strategies are presented. Finally, the NASA Integrated Radio and Optical Communications (iROC) project is described, which directly addresses the combined RF and optical approach.

  11. Space-based laser cross-link systems used in satellite communications

    NASA Astrophysics Data System (ADS)

    Panahi, Allen; Kazemi, Alex A.

    2009-05-01

    Space-based optical communications using satellites in low earth orbit (LEO) and Geo-synchronous orbits (GEO) hold great promise for the proposed Internet in the Sky network of the future. Building high speed communications network using optical links in space has proven to be an extremely complicated task and many such schemes were tried without success in the past. However in the last few years, there has been impressive progress made to bring the concept to fruition in civilian and government-non classified projects. Laser Communications offer a viable alternative to established RF communications for inter-satellite links and other applications where high performance links are a necessity. High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design. This paper will focus on the requirements of the spacebased lasers and optics used for beam forming, as well as receiver antenna gain and detectors used in free space communications. Also discussed are the critical parameters in the transmitter, channel, receiver, and link budget that are employed in successful inter-satellite communications system.

  12. Preparation to optical communication experiments with geostationary satellite ARTEMIS

    NASA Astrophysics Data System (ADS)

    Kuzkov, V. P.; Medveskij, M. M.; Yatskiv, D. Ya.; Nedashkovskij, V. N.; Suberlak, V. R.; Glushchenko, Yu. M.; Peretyatko, M. M.; Eremenko, N. A.

    2003-08-01

    We considered necessary conditions and performed expedient calculations for performing laser communication link experiments with geostationary satellite ARTEMIS (ESA). The scheme was proposed of performing these experiments by using two telescopes. The results of observation of the satellite are presented.

  13. The optical communication link outage probability in satellite formation flying

    NASA Astrophysics Data System (ADS)

    Arnon, Shlomi; Gill, Eberhard

    2014-02-01

    In recent years, several space systems consisting of multiple satellites flying in close formation have been proposed for various purposes such as interferometric synthetic aperture radar measurement (TerraSAR-X and the TanDEM-X), detecting extra-solar earth-like planets (Terrestrial Planet Finder-TPF and Darwin), and demonstrating distributed space systems (DARPA F6 project). Another important purpose, which is the concern of this paper, is for improving radio frequency communication to mobile terrestrial and maritime subscribers. In this case, radio frequency signals from several satellites coherently combine such that the received/transmit signal strength is increased proportionally with the number of satellites in the formation. This increase in signal strength allows to enhance the communication data rate and/or to reduce energy consumption and the antenna size of terrestrial mobile users' equipment. However, a coherent combination of signals without aligning the phases of the individual communication signals interrupts the communication and outage link between the satellites and the user. The accuracy of the phase estimation is a function of the inter-satellite laser ranging system performance. This paper derives an outage probability model of a coherent combination communication system as a function of the pointing vibration and jitter statistics of an inter-satellite laser ranging system tool. The coherent combination probability model, which could be used to improve the communication to mobile subscribers in air, sea and ground is the main importance of this work.

  14. High speed all-optical data processing in fast semiconductor and optical fiber based devices

    NASA Astrophysics Data System (ADS)

    Sun, Hongzhi

    Future generations of communication systems demand ultra high speed data processing and switching components. Conventional electrical parts have reached their bottleneck both speed-wise and efficiency-wise. The idea of manipulating high speed data in optical domain is gaining more popularity. In this PhD thesis work, we proposed and demonstrated various schemes of all-optical Boolean logic gate at data rate as high as 80Gb/s by using semiconductor optical amplifier (SOA), SOA Mach-Zehnder interferometer (SOA-MZI), highly nonlinear fiber (HNLF) and optical fiber based components. With the invention of quantum dot (QD) based semiconductor devices, speed limit of all optical data processing has a chance to boost up to 250Gb/s. We proposed and simulated QD-SOA based Boolean functions, and their application such as shift register and pseudorandom bit sequence generation (PRBS). Clock and data recovery of high speed data signals has been simulated and demonstrated by injection lock and phase lock loop techniques in a fiber and SOA ring and an optical-electrical (OE) feedback loop.

  15. Development of microlens arrays for high-speed optical communication

    NASA Astrophysics Data System (ADS)

    Ko, Chih-Hsiang; Lin, Chun-Hsu; Tsai, Bor-Chen; Shih, His-Hsin; Wu, Chien-Tsung; Chao, Yu-Lin; Chou, Yu-Kon; Chu, Chun-Hsun; Chiou, Yii-Tay; Chen, Rax

    2004-09-01

    In this study, polymeric microlens arrays, well suited for high-volume and low-cost production, were developed for efficiently coupling the light from vertical-cavity surface emitting lasers (VCSELs) to multi-mode fiber ribbon. They were fabricated by microinjection molding with Ni-electroplated mold insert. Modified LIGA processes and the Ni-electroplating are used to make the master and the metallic mold insert, respectively. In this study, microinjection molding with metallocene based cyclic olefin copolymer (mCOC) was chosen to replicate microlenses. Good surface profile and high dimensional accuracy are achieved. Coupling efficiency of 55 +/- 3 % with a working distance of 400 +/- 60 micrometer is obtained. To verify its applications on high-speed interconnections, we also designed the evaluated board and set up an opto-electronic measurement platform. The high-speed measurement shows that the electrical-to-optical conversion 3dB-bandwidth is above 1.8 GHz, and the eye diagram at 2.488 Gbps is acceptable for the SONET OC-48 eye mask.

  16. Hybrid microtransmitter for free-space optical spacecraft communication: design, manufacturing, and characterization

    NASA Astrophysics Data System (ADS)

    Lotfi, Sara; Palmer, Kristoffer; Kratz, Henrik; Thornell, Greger

    2009-02-01

    Optical intra-communication links are investigated by several currently operational qualification missions. Compared with RF communication systems, the optical domain obtains a wider bandwidth, enables miniaturized spacecraft and reduced power consumption. In this project, a microtransmitter is designed and manufactured for formation flying spacecraft with transmission rates of 1 Gbit/s. Simulations in Matlab and Simulink show that a BER of 10-9 can be achieved with aperture sizes of 1 cm and a transmitter output peak power of 12 mW for a distance of 10 km. The results show that the performance of the communication link decreases due to mechanical vibrations in the spacecraft together with a narrow laser beam. A dual-axis microactuator designed as a deflectable mirror has been developed for the laser beam steering where the fabrication is based on a double-sided, bulk micromachining process. The mirror actuates by joints consisting of v-grooves filled with SU-8 polymer. The deflection is controlled by integrated resistive heaters in the joints causing the polymer to expand thermally. Results show that the mirror actuates 20-30° in the temperature interval 25-250°C. Flat Fresnel lenses made of Pyrex 7740 are used to collimate the laser beam. These lenses are simulated in the Comsol software and optimized for a 670 nm red VCSEL. The lenses are manufactured using lithography and reactive ion etching. All tests are made in a normal laboratory environment, but the effect of the space environment is discussed.

  17. Measurement-based noiseless linear amplification for quantum communication

    NASA Astrophysics Data System (ADS)

    Chrzanowski, H. M.; Walk, N.; Haw, J. Y.; Thearle, O.; Assad, S. M.; Janousek, J.; Hosseini, S.; Ralph, T. C.; Symul, T.; Lam, P. K.

    2014-11-01

    Entanglement distillation is an indispensable ingredient in extended quantum communication networks. Distillation protocols are necessarily non-deterministic and require non-trivial experimental techniques such as noiseless amplification. We show that noiseless amplification could be achieved by performing a post-selective filtering of measurement outcomes. We termed this protocol measurement-based noiseless linear amplification (MBNLA). We apply this protocol to entanglement that suffers transmission loss of up to the equivalent of 100km of optical fibre and show that it is capable of distilling entanglement to a level stronger than that achievable by transmitting a maximally entangled state through the same channel. We also provide a proof-of-principle demonstration of secret key extraction from an otherwise insecure regime via MBNLA. Compared to its physical counterpart, MBNLA not only is easier in term of implementation, but also allows one to achieve near optimal probability of success.

  18. The Couples' Gender-Based Communication Questionnaire (CGCQ).

    ERIC Educational Resources Information Center

    Eckstein, Daniel; Goldman, Alan

    2001-01-01

    Effective communication is a cornerstone of marital happiness. The Couples' Gender-Based Communication Questionnaire is presented as a method for identifying male-female different communication styles. Suggests that once people realize that their partners have different conversational styles, they are inclined to accept difference without blaming…

  19. Novel optical devices based on the tunable refractive index of magnetic fluid and their characteristics

    NASA Astrophysics Data System (ADS)

    Zhao, Yong; Zhang, Yuyan; Lv, Riqing; Wang, Qi

    2011-12-01

    As a new type of functional material, magnetic fluid (MF) is a stable colloid of magnetic nanoparticles, dressed with surfactant and dispersed in the carrier liquid uniformly. The MF has many unique optical properties, and the most important one is its tunable refractive index property. This paper summarizes the properties of the MF refractive index and the related optical devices. The refractive index can be easily controlled by external magnetic field, temperature, and so on. But the tunable refractive index of MF has a relaxation effect. As a result, the response time is more than milliseconds and the MF is only suitable for low speed environment. Compared with the traditional optical devices, the magnetic fluid based optical devices have the tuning ability. Compared with the tunable optical devices (the electro-optic devices (LiNbO3) of more than 10 GHz modulation speed, acoustic-optic devices (Ge) of more than 20 MHz modulation speed), the speed of the magnetic fluid based optical devices is low. Now there are many applications of magnetic fluid based on the refractive index in the field of optical information communication and sensing technology, such as tunable beam splitter, optical-fiber modulator, tunable optical gratings, tunable optical filter, optical logic device, tunable interferometer, and electromagnetic sensor. With the development of the research and application of magnetic fluid,a new method, structure and material to improve the response time can be found, which will play an important role in the fields of optical information communication and sensing technology.

  20. Novel Applications of Chirp Managed Laser in Optical Fiber Communication Systems

    NASA Astrophysics Data System (ADS)

    Jia, Wei

    Nowadays, with the dramatically growing bandwidth requirement of Internet, the number of wavelength division multiplexing (WDM) channels of the optical fiber communication systems is increasing rapidly. Hence, optical transmitters with cost effectiveness, high power efficiency, and excellent transmission performance are necessary. Especially, for access and metropolitan applications, simple configuration is the essential factor. The conventional optical transmitter is composed of a laser as continuous-wave (CW) source and one or more external modulators for modulation. However, the high insertion loss, large driving voltage, and extra cost of external modulator make it relatively bulky and power-hungry. Chirp managed laser (CML), comprising a directly modulated semiconductor laser (DML) and a passive optical filter, is an alternative promising transmitter candidate. It has the merits of smaller device size, lower cost, less power consumption, and higher fiber chromatic dispersion (CD) tolerance, compared with that based on external modulator. In this thesis, we have investigated several novel applications of CML in optical fiber communication systems, taking advantage of its unique phase modulating and spectral reshaping properties. These topics include optical return-to-zero (RZ) pulses generation using CML, M-ary RZ differential phase-shift-keying (RZ-DPSK) signals generation using CML, and enhanced CD tolerance of CML with pre-emphasis. These CML-based designs consume low power for less electrical pre-coding, require reduced or no external modulator, and show notable transmission performances. Optical RZ pulses generation using CML: RZ pulses have been widely used in optical fiber communication systems together with on-off-keying (OOK) and DPSK modulation formats, for its high robustness towards inter symbol interference (ISI) and nonlinear distortions. In this thesis, we propose and experimentally demonstrate the technique of 10-Gb/s optical RZ pulses

  1. Improved Climatological Characterization of Optical Turbulence for Space Optical Imaging and Communications

    NASA Astrophysics Data System (ADS)

    Alliss, R.; Felton, B.

    2010-09-01

    Optical turbulence (OT) acts to distort light in the atmosphere, degrading imagery from astronomical or other telescopes. In addition, the quality of service of a free space optical communications link may also be impacted. Some of the degradation due to turbulence can be corrected by adaptive optics. However, the severity of optical turbulence, and thus the amount of correction required, is largely dependent upon the turbulence at the location of interest. Therefore, it is vital to understand the climatology of optical turbulence at such locations. In many cases, it is impractical and expensive to setup instrumentation to characterize the climatology of OT, particularly for OCONUS locations, so simulations become a less expensive and convenient alternative. The strength of OT is characterized by the refractive index structure function Cn2, which in turn is used to calculate atmospheric seeing parameters. While attempts have been made to characterize Cn2 using empirical models, Cn2 can be calculated more directly from Numerical Weather Prediction (NWP) simulations using pressure, temperature, thermal stability, vertical wind shear, turbulent Prandtl number, and turbulence kinetic energy (TKE). In this work we use the Weather Research and Forecast (WRF) NWP model to generate Cn2 climatologies in the planetary boundary layer and free atmosphere, allowing for both point-to-point and ground-to-space seeing estimates of the Fried Coherence length (ro) and other seeing parameters. Simulations are performed using the Maui High Performance Computing Centers (MHPCC) Mana cluster. The WRF model is configured to run at 1km horizontal resolution over a domain covering several hundreds of kilometers. The vertical resolution varies from 25 meters in the boundary layer to 500 meters in the stratosphere. The model top is 20 km. We are interested in the variations in Cn2 and the Fried Coherence Length (ro). Nearly two years of simulations have been performed over various regions

  2. Semiconductor devices for optical communications in 1 micron band of wavelength. [gallium indium arsenide phosphide lasers and diodes

    NASA Technical Reports Server (NTRS)

    Suematsu, Y.; Iga, K.

    1980-01-01

    Crystal growth and the characteristics of semiconductor lasers and diodes for the long wavelength band used in optical communications are examined. It is concluded that to utilize the advantages of this band, it is necessary to have a large scale multiple wavelength communication, along with optical cumulative circuits and optical exchangers.

  3. Retro-modulators and fast beam steering for free-space optical communications

    NASA Astrophysics Data System (ADS)

    Chan, Trevor Keith

    Free-space optical (FSO) communications is a means of secure, high bandwidth communication through the use of a modulated laser beam in free-space as the information medium. The chaotic nature of the atmosphere and the motion of the communication nodes make laser alignment a crucial concern. The employment of retro-reflecting modulators makes the bidirectional quality of a communication link into a one sided alignment problem. While there are existing retro-reflecting modulators, their trade-offs create a lack of abilities (such as aperture size, angular range, high modulation speeds, economic viability) which do not fulfill the requirements for certain applications. Also, the beam must be directed towards the intended receiver. Form mobile or scintillated communication links, beam direction must be adaptable in real time. Once again, this area suffers from trade-offs where beamsteering speed is often limited. Research used to mitigate the trade-offs and adapt the devices into viable options for a wider range of applications is explored in this dissertation. Two forms of retro-modulators were explored; a MEMS deformable mirror retro-modulator and a solid silicon retro-modulator that modulated the light by frustrated total internal reflection (FTIR). The MEMS version offered a high speed, scalable, wavelength/angle insensitive retro-modulator which can be massed produced at low cost, while the solid retro-modulator offered a large field of view with low cost as well. Both modulator's design, simulated performances, fabrication and experimental characterization are described in this dissertation. An ultra-fast beamscanner was also designed using 2-dimensional dispersion. By using wavelength switching for directional control, a beamscanner was developed that could switch light faster than pre-existing beamscanners while the beams characteristics (most importantly its aperture) could be freely adjusted by the independent optics. This beamscanner was preceded by our

  4. A Shuttle based laser system for space communication

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, Michael W.; Bruno, Ronald C.

    1988-01-01

    A key element of NASA-Goddard's plan for future laser space communications is the Space Shuttle-based Laser Technology Experiments Facility (LTEF), which will be designed to communicate with a cooperative laser system under development for the Advanced Communication Technology Satellite (ACTS) and will conduct a comprehensive set of acquisition, tracking, and communication experiments. Attention is presently given to the challenges faced by designers in achieving LTEF acquisition of the ACTS downlink beacon laser.

  5. Novel optical devices based on the transmission properties of magnetic fluid and their characteristics

    NASA Astrophysics Data System (ADS)

    Zhao, Yong; Lv, Riqing; Zhang, Yuyan; Wang, Qi

    2012-09-01

    Magnetic fluid has many unique optical properties. It has numerous potential applications in developing optical devices because of its versatile optical properties. This paper summarizes the physical origins and control mechanisms of the MF transmission properties, and the related optical devices based on the transmission properties of magnetic fluid. In recent years, there are many applications in optical information communication and sensing technology, such as optical switches, tunable optical gratings, coarse wavelength-division multiplexing, magnetic-field sensors, current sensor. The qualitative and quantitative analysis about the physical configuration, the operating principle, and the characteristics of those optical devices are given. The valuable potential problems and the solutions that are related to optical properties and optical devices based on magnetic fluid are expounded in detail, and potential new types of MF-based optical devices are proposed. It can be concluded that the transmission properties of MF will be improved greatly, and the characteristics of present optical devices based on magnetic fluid will be made better continually and it will play an important role in the fields of optical information communication and sensing technology.

  6. Single Fiber Star Couplers. [optical waveguides for spacecraft communication

    NASA Technical Reports Server (NTRS)

    Asawa, C. K.

    1979-01-01

    An ion exchange process was developed and used in the fabrication of state-of-the-art planar star couplers for distribution of optical radiation between optical fibers. An 8 x 8 planar transmission star coupler was packaged for evaluation purposes with sixteen fiber connectors and sixteen pigtails. Likewise a transmission star coupler and an eight-port reflection star coupler with eight-fiber ribbons rigidly attached to these couplers, and a planar coupler with silicon guides and a parallel channel guide with pigtails were also fabricated. Optical measurements of the transmission star couplers are included with a description of the manufacturing process.

  7. Performance analysis of pupil-matching optical differential receivers in space-to-ground laser communication.

    PubMed

    Ma, Xiaoping; Sun, Jianfeng; Zhi, Ya'nan; Zhou, Yu; Lu, Wei; Hou, Peipei; Xu, Qian; Liu, Liren

    2014-05-10

    In the paper, the principle and structure of a pupil-matching optical differential receiver consisting of double 4f confocal lens groups is introduced to overcome atmosphere turbulences in space-to-ground laser communication. Using the scalar diffraction theory, a systematic analysis of 4f lens groups is formulated mathematically. Based on Seidel aberration, lens aberrations produced by the inherent unideal lens and mutual alignment errors of double 4f lens groups primarily caused by relative axial displacement of the foci and vertical position change of the optical axes are studied mathematically and detailed. Under the effects of varying aberrations on the double 4f lens groups, we evaluate the performance of this receiving system by the model of power penalty for a given 10(-9) bit error ratio. Simulated results of the relationship between power penalty and the different root-mean-square errors are concluded in order to put forward the requirement of machining precision of individual components. That will be helpful in optimizing the design of these groups in the optical receiver. PMID:24922020

  8. Design, fabrication and characterisation of nano-imprinted single mode waveguide structures for intra-chip optical communications

    NASA Astrophysics Data System (ADS)

    Justice, John; Khan, Umar; Korhonen, Tia; Boersma, Arjen; Wiegersma, Sjoukje; Karppinen, Mikko; Corbett, Brian

    2015-03-01

    In the Information and Communications Technology (ICT) sector, the demands on bandwidth continually grow due to increased microprocessor performance and the need to access ever increasing amounts of stored data. The introduction of optical data transmission (e.g. glass fiber) to replace electronic transmission (e.g. copper wire) has alleviated the bandwidth issue for communications over distances greater than 10 meters, however, the need has arisen for optical data transfer over shorter distances such as those found inside computers. A possible solution for this is the use of low-cost single mode polymer based optical waveguides fabricated by direct patterning Nanoimprint Lithography (NIL). NIL has emerged as a scalable manufacturing technology capable of producing features down to the hundred nanometer scale with the potential for large scale (roll-to-roll) manufacturing. In this paper, we present results on the modeling, fabrication and characterization of single mode waveguides and optical components in low-loss ORMOCER™ materials. Single mode waveguides with a mode field diameter of 7 μm and passive structures such as bends, directional couplers and multi-mode interferometers (MMIs) suitable for use in 1550 nm optical interconnects were fabricated using wafer scale NIL processes. Process issues arising from the nano-imprint technique such as residual layers and angled sidewalls are modeled and investigated for excess loss and higher order mode excitation. Conclusions are drawn on the applicability of nano-imprinting to the fabrication of circuits for intrachip/ board-level optical interconnect.

  9. Fiber optic-based biosensor

    NASA Technical Reports Server (NTRS)

    Ligler, Frances S.

    1991-01-01

    The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

  10. Entanglement-Based Quantum Cryptography and Quantum Communication

    NASA Astrophysics Data System (ADS)

    Zeilinger, Anton

    2007-03-01

    Quantum entanglement, to Erwin Schroedinger the essential feature of quantum mechanics, has become a central resource in various quantum communication protocols including quantum cryptography and quantum teleportation. From a fundamental point of view what is exploited in these experiments is the very fact which led Schroedinger to his statement namely that in entangled states joint properties of the entangled systems may be well defined while the individual subsystems may carry no information at all. In entanglement-based quantum cryptography it leads to the most elegant possible solution of the classic key distribution problem. It implies that the key comes into existence at spatially distant location at the same time and does not need to be transported. A number recent developments include for example highly efficient, robust and stable sources of entangled photons with a broad bandwidth of desired features. Also, entanglement-based quantum cryptography is successfully joining other methods in the work towards demonstrating quantum key distribution networks. Along that line recently decoy-state quantum cryptography over a distance of 144 km between two Canary Islands was demonstrated successfully. Such experiments also open up the possibility of quantum communication on a really large scale using LEO satellites. Another important possible future branch of quantum communication involves quantum repeaters in order to cover larger distances with entangled states. Recently the connection of two fully independent lasers in an entanglement swapping experiment did demonstrate that the timing control of such systems on a femtosecond time scale is possible. A related development includes recent demonstrations of all-optical one-way quantum computation schemes with the extremely short cycle time of only 100 nanoseconds.

  11. Free-space optical communications using encoding of data on different orbital-angular-momentum modes

    NASA Astrophysics Data System (ADS)

    Willner, Asher J.; Ren, Yongxiong; Xie, Guodong; Li, Long; Cao, Yinwen; Zhao, Zhe; Liao, Peicheng; Wang, Zhe; Yan, Yan; Ahmed, Nisar; Liu, Cong; Tur, Moshe; Willner, Alan E.

    2016-03-01

    Free-space optical communications can play a significant role in line-of-sight links. In general, data can be encoded on the amplitude, phase, or temporal position of the optical wave. Importantly, there are environments for which ever-more information is desired for a given amount of optical energy. This can be accomplished if there are more degrees-of-freedom that the wave can occupy to provide higher energy efficiency for a given capacity (i.e., bits/photon). Traditionally, free-space optical links have used only a single beam, such that there was little opportunity for a wave to occupy more than one spatial location, thereby not allowing the spatial domain to be used for data encoding. Recently, space- and mode-multiplexing has been demonstrated to simultaneously transmit multiple data-carrying free-space beams. Each spatially overlapping mode was orthogonal to other modes and carried a unique amount of orbital-angular-momentum (OAM). In this paper, we consider that OAM modes could be a data-encoding domain, such that a beam could uniquely occupy one of many modes, i.e., 4 modes would provide 4 possible states and double the bits of information for the same amount of energy. In the past, such OAM-based encoding was shown at kHz data rates. We will present the architecture and experimental results for OAM-based data encoding for a free-space 1.55-μm data link under different system parameters. Key features of the results include: (a) encoding on several modes is accomplished using a fast switch, and (b) low bit-error-rates are achieved at >Gbit/s, which is orders-of-magnitude faster than previous results.

  12. Compact dual channel optical fiber amplifier for space communication applications

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Henwood-Moroney, L.; Hosking, P.; Kehayas, E.; Stampoulidis, L.; Robertson, A.

    2015-03-01

    We present results from the development of a dual channel Optical Fiber Amplifier (OFA) that consists of two copropagating low noise EDFAs at 1565 and 1545nm. The two channels have separate outputs but can also be combined via an optical switch to a common output channel for an increased output signal power. The OFA produces up to 35dB gain at low signal input powers and a total of over 350mW optical signal power combined from both EDFA channels with a 5mW signal input. The OFA was tested with input signals between 0.1 - 20 mW over the C-band and with pump power varying from 0 - 100% of the maximum operating pump power. The OFA module has total mass of 583 g including all electrical and optical components, as well as optical and electrical bulkheads, and a total module volume of 430 cm3. The module was also radiation tested via gamma irradiation up to 100 krad TID, validating the robustness of the optical amplifier against RIA effects and its suitability for LEO and GEO satellite missions.

  13. Underwater optical communications with a single photon-counting system

    NASA Astrophysics Data System (ADS)

    Hiskett, Philip A.; Lamb, Robert A.

    2014-05-01

    This paper discusses the system engineering challenges involved with the transmission of optically encoded data through water. The scenarios of data transmission from an airborne platform to a submerged platform and data transmission from a submerged platform to another submerged platform will be discussed. A photon-counting experimental system was constructed to investigate the transmission of optical data through a 1m long tank of water. This test system incorporated a laser diode operating at a wavelength of 450nm and an optical receiver containing a shallow junction, silicon single photon avalanche diode. The optical data was transmitted through the tank containing ~100 litres of water at transmission rates equivalent to 40Mb/s. The attenuation of the optical path was increased by increasing the level of scattering of the photons using Maalox. The effects on the temporal distribution of photons in the optical pulse from adding Maalox are also discussed. The synchronisation of the transmitter and receiver clocks was investigated using reference headers appended to the encoded message signal which the receiver used to correct for timing drift. The performance of this experimental system and experimental results are discussed.

  14. Optical Phase-Locked Loops: Performance Investigation and Psk Synchronous Communication System Experiments

    NASA Astrophysics Data System (ADS)

    Atlas, Dogan A.

    1990-01-01

    This thesis study presents the design/analysis considerations, fundamental performance limitations and the experimental set-up of an optical phase-locked loop which is employed in phase-shift keying homodyne and synchronous heterodyne optical fiber communication system experiments. From an optical communication systems point of view, the characteristics of the lightwave sources to be used are important to investigate. Therefore, frequency modulation, frequency noise and intensity noise characteristics of 1320-nm (227 THz) laser-diode-pumped miniature Nd:YAG ring lasers have been investigated. The modulation and noise properties of these lasers are characterized both qualitatively and quantitatively. For applications such as optical phase-locking, phase-shift keying homodyne and synchronous heterodyne optical fiber and optical free -space communication systems, subcarrier multiplexing systems, and microwave phase array antennas diode-pumped Nd:YAG lasers are excellent lightwave sources. The reasons that make these lasers attractive candidates for such a variety of applications include the narrow laser linewidth, the uniformly flat frequency modulation response and the wide frequency modulation bandwidth. A stable second-order optical phase-locked loop has been constructed using two Nd:YAG lasers and a balanced optical receiver. The loop is designed so that the local oscillator laser locks to the frequency/phase variations of the transmitter laser. The frequency/phase tracking performance of the loop is limited by the quantum phase noise and mainly by the frequency drift induced by the temperature variations of both the transmitter and local oscillator laser cavities. Using the loop, optical phase -shift keying homodyne communication system experiments are demonstrated at modulation rates of 140 Mb/s and 2 Gb/s. The receiver sensitivity at 140 Mb/s is 25 photons/bit which is the highest sensitivity reported to date with any optical communication system. An optical

  15. Displacement damage in bit error ratio performance of on-off keying, pulse position modulation, differential phase shift keying, and homodyne binary phase-shift keying-based optical intersatellite communication system.

    PubMed

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Zhao, Jing; Dong, Chen; Li, Xuan

    2016-04-10

    Displacement damage (DD) effect induced bit error ratio (BER) performance degradations in on-off keying (OOK), pulse position modulation (PPM), differential phase-shift keying (DPSK), and homodyne binary phase shift keying (BPSK) based systems were simulated and discussed under 1 MeV neutron irradiation to a total fluence of 1×1012  n/cm2 in this paper. Degradation of main optoelectronic devices included in communication systems were analyzed on the basis of existing experimental data. The system BER degradation was subsequently simulated and the variations of BER with different neutron irradiation location were also achieved. The result shows that DD on an Er-doped fiber amplifier (EDFA) is the dominant cause of system degradation, and a BPSK-based system performs better than the other three systems against DD. In order to improve radiation hardness of communication systems against DD, protection and enhancement of EDFA are required, and the use of a homodyne BPSK modulation scheme is a considered choice. PMID:27139876

  16. Multi-carrier transmission for hybrid radio frequency with optical wireless communications

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Chen, Genshe; Shen, Dan; Pham, Khanh; Blasch, Erik; Nguyen, Tien M.

    2015-05-01

    Radio frequency (RF) wireless communication is reaching its capacity to support large data rate transmissions due to hardware constraints (e.g., silicon processes), software strategies (e.g., information theory), and consumer desire for timely large file exchanges (e.g., big data and mobile cloud computing). A high transmission rate performance must keep pace with the generated huge volumes of data for real-time processing. Integrated RF and optical wireless communications (RF/OWC) could be the next generation transmission technology to satisfy both the increased data rate exchange and the communications constraints. However, with the promising benefits of RF/OWC, challenges remain to fully develop hybrid RF with wireless optical communications such as uniform waveform design for information transmission and detection. In this paper, an orthogonal frequency division multiplexing (OFDM) transmission scheme, which widely employed in RF communications, is developed for optical communications. The traditional high peak-to-average power ratio (PAPR) in OFDM is reduced to improve system performance. The proposed multi-carrier waveform is evaluated with a frequency-selective fading channel. The results demonstrate that bit error rate (BER) performance of our proposed optical OFDM transmission technique outperforms the traditional OWC on-off keying (OOK) transmission scheme.

  17. The investigation and prospect on optical principles of multiple space laser communication

    NASA Astrophysics Data System (ADS)

    Zhang, Yalin; An, Yan; Jiang, Huilin; Jiang, Lun; Wang, Chao; Zhan, Juntong; Han, Long

    2015-10-01

    Multiple laser communication is the key point of integrated space-ground network system, and it is the necessary prerequisite of realizing the network communication link between multiple satellites. In this paper, current situation and the development status of multiple laser communication are introduced, then optical principles and methods of multiple laser communication are discussed, and advantages and disadvantages are compared and analyzed with different multiple space laser communication system. The systems were classified according to different principles, including the simple principle type, exchange points type, RF and laser combined type, field expanding type and large field communication type. Then we look into the future of multiple laser communication systems, and the result shows that the paraboloid of revolution type has great potential in the future's laser communication space network ,for it's large communication range and high energy efficiency. It can be used to communicate between the aircraft platform, airship platforms and satellite platforms. Which laid the foundation for the future development of the laser communication space network.

  18. Active disturbance rejection controller of fine tracking system for free space optical communication

    NASA Astrophysics Data System (ADS)

    Cui, Ning; Liu, Yang; Chen, Xinglin; Wang, Yan

    2013-08-01

    Free space optical communication is one of the best approaches in future communications. Laser beam's acquisition, pointing and tracking are crucial technologies of free space optical communication. Fine tracking system is important component of APT (acquisition, pointing and tracking) system. It cooperates with the coarse pointing system in executing the APT mission. Satellite platform vibration and disturbance, which reduce received optical power, increase bit error rate and affect seriously the natural performance of laser communication. For the characteristic of satellite platform, an active disturbance rejection controller was designed to reduce the vibration and disturbance. There are three major contributions in the paper. Firstly, the effects of vibration on the inter satellite optical communications were analyzed, and the reasons and characters of vibration of the satellite platform were summarized. The amplitude-frequency response of a filter was designed according to the power spectral density of platform vibration of SILEX (Semiconductor Inter-satellite Laser Experiment), and then the signals of platform vibration were generated by filtering white Gaussian noise using the filter. Secondly, the fast steering mirror is a key component of the fine tracking system for optical communication. The mechanical design and model analysis was made to the tip/tilt mirror driven by the piezoelectric actuator and transmitted by the flexure hinge. The transfer function of the fast steering mirror, camera, D/A data acquisition card was established, and the theory model of transfer function of this system was further obtained. Finally, an active disturbance rejection control method is developed, multiple parallel extended state observers were designed for estimation of unknown dynamics and external disturbance, and the estimated states were used for nonlinear feedback control and compensation to improve system performance. The simulation results show that the designed

  19. Graphene-Based Optical Biosensors and Imaging

    SciTech Connect

    Tang, Zhiwen; He, Shijiang; Pei, Hao; Du, Dan; Fan, Chunhai; Lin, Yuehe

    2014-01-13

    This chapter focuses on the design, fabrication and application of graphene based optical nanobiosensors. The emerging graphene based optical nanobiosensors demonstrated the promising bioassay and biomedical applications thanking to the unique optical features of graphene. According to the different applications, the graphene can be tailored to form either fluorescent emitter or efficient fluorescence quencher. The exceptional electronic feature of graphene makes it a powerful platform for fabricating the SPR and SERS biosensors. Today the graphene based optical biosensors have been constructed to detect various targets including ions, small biomolecules, DNA/RNA and proteins. This chapter reviews the recent progress in graphene-based optical biosensors and discusses the opportunities and challenges in this field.

  20. Teaching Communication with Ethics-Based Cases.

    ERIC Educational Resources Information Center

    Stevens, Betsy

    1996-01-01

    Argues the importance of presenting ethics and communication as twin concepts in the management communication class. Presents two cases useful in the classroom that address two contemporary issues (harassment in the workplace and the consumption of alcohol by pregnant women) that have implications for business professionals and allow students to…

  1. Study of optimum methods of optical communication. [accounting for the effects of the turbulent atmosphere and quantum mechanics

    NASA Technical Reports Server (NTRS)

    Harger, R. O.

    1974-01-01

    Abstracts are reported relating to the techniques used in the research concerning optical transmission of information. Communication through the turbulent atmosphere, quantum mechanics, and quantum communication theory are discussed along with the results.

  2. High-dimensional structured light coding/decoding for free-space optical communications free of obstructions.

    PubMed

    Du, Jing; Wang, Jian

    2015-11-01

    Bessel beams carrying orbital angular momentum (OAM) with helical phase fronts exp(ilφ)(l=0;±1;±2;…), where φ is the azimuthal angle and l corresponds to the topological number, are orthogonal with each other. This feature of Bessel beams provides a new dimension to code/decode data information on the OAM state of light, and the theoretical infinity of topological number enables possible high-dimensional structured light coding/decoding for free-space optical communications. Moreover, Bessel beams are nondiffracting beams having the ability to recover by themselves in the face of obstructions, which is important for free-space optical communications relying on line-of-sight operation. By utilizing the OAM and nondiffracting characteristics of Bessel beams, we experimentally demonstrate 12 m distance obstruction-free optical m-ary coding/decoding using visible Bessel beams in a free-space optical communication system. We also study the bit error rate (BER) performance of hexadecimal and 32-ary coding/decoding based on Bessel beams with different topological numbers. After receiving 500 symbols at the receiver side, a zero BER of hexadecimal coding/decoding is observed when the obstruction is placed along the propagation path of light. PMID:26512460

  3. Coherent detection and digital signal processing for fiber optic communications

    NASA Astrophysics Data System (ADS)

    Ip, Ezra

    The drive towards higher spectral efficiency in optical fiber systems has generated renewed interest in coherent detection. We review different detection methods, including noncoherent, differentially coherent, and coherent detection, as well as hybrid detection methods. We compare the modulation methods that are enabled and their respective performances in a linear regime. An important system parameter is the number of degrees of freedom (DOF) utilized in transmission. Polarization-multiplexed quadrature-amplitude modulation maximizes spectral efficiency and power efficiency as it uses all four available DOF contained in the two field quadratures in the two polarizations. Dual-polarization homodyne or heterodyne downconversion are linear processes that can fully recover the received signal field in these four DOF. When downconverted signals are sampled at the Nyquist rate, compensation of transmission impairments can be performed using digital signal processing (DSP). Software based receivers benefit from the robustness of DSP, flexibility in design, and ease of adaptation to time-varying channels. Linear impairments, including chromatic dispersion (CD) and polarization-mode dispersion (PMD), can be compensated quasi-exactly using finite impulse response filters. In practical systems, sampling the received signal at 3/2 times the symbol rate is sufficient to enable an arbitrary amount of CD and PMD to be compensated for a sufficiently long equalizer whose tap length scales linearly with transmission distance. Depending on the transmitted constellation and the target bit error rate, the analog-to-digital converter (ADC) should have around 5 to 6 bits of resolution. Digital coherent receivers are naturally suited for the implementation of feedforward carrier recovery, which has superior linewidth tolerance than phase-locked loops, and does not suffer from feedback delay constraints. Differential bit encoding can be used to prevent catastrophic receiver failure due

  4. Performance Analysis of Different Modulation Formats in Optical Communication

    NASA Astrophysics Data System (ADS)

    Singh, Kulwinder; Singh, Maninder; Bhatia, Kamaljit Singh; Ryait, Hardeep Singh

    2016-06-01

    In this paper, we demonstrated the variation of different parameters with quadrature amplitude modulation (QAM) and differential phase shift key (DPSK) sequence generator, which generates modulated signals, in data transmission for communication and analysed that how the difference of these sequence generators effect its resonant frequency (RF) value, eye diagram and electrical constellation representation of the system.

  5. Fabrication of Optical Devices Based on Printable Photonics Technology and Its Application for Biosensor

    NASA Astrophysics Data System (ADS)

    Endo, Tatsuro; Okuda, Norimichi; Yanagida, Yasuko; Tanaka, Satoru; Hatsuzawa, Takeshi

    The specific optical characteristics which can be observed nanostructured optical device have great potentials for applying to several applications such as lifescience, optical communications, and data storage. Application of nanostrcutured optical device to industry, we suggest “printable photonics technology” for fabrication of nanostructured optical device based on nanoimprint lithography (NIL). In this study, using printable photonics technology, fabrication of flexible photonic crystal (PC) and its application for biosensor was performed. Using printable photonics technology-based PC for biosensing application, high sensitive detection of protein adsorption (detection limit: 1 pg/ml) could be detected.

  6. Scheduling for indoor visible light communication based on graph theory.

    PubMed

    Tao, Yuyang; Liang, Xiao; Wang, Jiaheng; Zhao, Chunming

    2015-02-01

    Visible light communication (VLC) has drawn much attention in the field of high-rate indoor wireless communication. While most existing works focused on point-to-point VLC technologies, few studies have concerned multiuser VLC, where multiple optical access points (APs) transmit data to multiple user receivers. In such scenarios, inter-user interference constitutes the major factor limiting the system performance. Therefore, a proper scheduling scheme has to be proposed to coordinate the interference and optimize the whole system performance. In this work, we aim to maximize the sum rate of the system while taking into account user fairness by appropriately assigning LED lamps to multiple users. The formulated scheduling problem turns out to be a maximum weighted independent set problem. We then propose a novel and efficient resource allocation method based on graph theory to achieve high sum rates. Moreover, we also introduce proportional fairness into our scheduling scheme to ensure the user fairness. Our proposed scheduling scheme can, with low complexity, achieve more multiplexing gains, higher sum rate, and better fairness than the existing works. PMID:25836136

  7. Emerging, Photonic Based Technologies for NASA Space Communications Applications

    NASA Technical Reports Server (NTRS)

    Pouch, John; Nguyen, Hung; Lee, Richard; Levi, Anthony; Bos, Philip; Titus, Charles; Lavrentovich, Oleg

    2002-01-01

    An objective of NASA's Computing, Information, and Communications Technology program is to support the development of technologies that could potentially lower the cost of the Earth science and space exploration missions, and result in greater scientific returns. NASA-supported photonic activities which will impact space communications will be described. The objective of the RF microphotonic research is to develop a Ka-band receiver that will enable the microwaves detected by an antenna to modulate a 1.55- micron optical carrier. A key element is the high-Q, microphotonic modulator that employs a lithium niobate microdisk. The technical approach could lead to new receivers that utilize ultra-fast, photonic signal processing techniques, and are low cost, compact, low weight and power efficient. The progress in the liquid crystal (LC) beam steering research will also be reported. The predicted benefits of an LC-based device on board a spacecraft include non-mechanical, submicroradian laser-beam pointing, milliradian scanning ranges, and wave-front correction. The potential applications of these emerging technologies to the various NASA missions will be presented.

  8. Use of Multiband Acousto-optic Filters for Spectrally Encoded Signals Generation in Incoherent Optical Communication Systems

    NASA Astrophysics Data System (ADS)

    Byshevski-Konopko, O. A.; Proklov, V. V.; Filatov, A. L.; Lugovskoi, A. V.; Korablev, E. M.

    New acousto-optical (AO) coder of spectrally optical signals for optical code division multiple access systems (O-CDMA) was proposed and investigated. The coder was developed on a base of multi-frequency acousto-optical filter (MAOF). Control RF signals for MAOF were synthesized taking into account intermodulation distortions and interferences between different carrier frequencies incoming to MAOF. An industrial LED was used under system investigation.

  9. Modulation based cells distribution for visible light communication.

    PubMed

    Wu, Yongsheng; Yang, Aiying; Feng, Lihui; Zuo, Lin; Sun, Yu-Nan

    2012-10-22

    Cells distribution for visible light communication can enhance the capacity of the data transmission by the reuse of optical spectrum. In this paper, we adopt three modulation formats as OOK, PPM and PWM for neighboring cells A, B and C respectively. The prototype experiment results demonstrate the error free transmission of 1.0 Mbit/s and 6.25 Mbit/s visible light communication system with our scheme. With the available LED, we can expect that the data rate of a visible light communication system with seamless connectivity can be up to 71.4 Mbit/s. PMID:23187182

  10. Infrared Cloud Imager Development for Atmospheric Optical Communication Characterization, and Measurements at the JPL Table Mountain Facility

    NASA Astrophysics Data System (ADS)

    Nugent, P. W.; Shaw, J. A.; Piazzolla, S.

    2013-02-01

    The continuous demand for high data return in deep space and near-Earth satellite missions has led NASA and international institutions to consider alternative technologies for high-data-rate communications. One solution is the establishment of wide-bandwidth Earth-space optical communication links, which require (among other things) a nearly obstruction-free atmospheric path. Considering the atmospheric channel, the most common and most apparent impairments on Earth-space optical communication paths arise from clouds. Therefore, the characterization of the statistical behavior of cloud coverage for optical communication ground station candidate sites is of vital importance. In this article, we describe the development and deployment of a ground-based, long-wavelength infrared cloud imaging system able to monitor and characterize the cloud coverage. This system is based on a commercially available camera with a 62-deg diagonal field of view. A novel internal-shutter-based calibration technique allows radiometric calibration of the camera, which operates without a thermoelectric cooler. This cloud imaging system provides continuous day-night cloud detection with constant sensitivity. The cloud imaging system also includes data-processing algorithms that calculate and remove atmospheric emission to isolate cloud signatures, and enable classification of clouds according to their optical attenuation. Measurements of long-wavelength infrared cloud radiance are used to retrieve the optical attenuation (cloud optical depth due to absorption and scattering) in the wavelength range of interest from visible to near-infrared, where the cloud attenuation is quite constant. This article addresses the specifics of the operation, calibration, and data processing of the imaging system that was deployed at the NASA/JPL Table Mountain Facility (TMF) in California. Data are reported from July 2008 to July 2010. These data describe seasonal variability in cloud cover at the TMF site

  11. Novel optical password security technique based on optical fractal synthesizer

    NASA Astrophysics Data System (ADS)

    Wu, Kenan; Hu, Jiasheng; Wu, Xu

    2009-06-01

    A novel optical security technique for safeguarding user passwords based on an optical fractal synthesizer is proposed. A validating experiment has been carried out. In the proposed technique, a user password is protected by being converted to a fractal image. When a user sets up a new password, the password is transformed into a fractal pattern, and the fractal pattern is stored in authority. If the user is online-validated, his or her password is converted to a fractal pattern again to compare with the previous stored fractal pattern. The converting process is called the fractal encoding procedure, which consists of two steps. First, the password is nonlinearly transformed to get the parameters for the optical fractal synthesizer. Then the optical fractal synthesizer is operated to generate the output fractal image. The experimental result proves the validity of our method. The proposed technique bridges the gap between digital security systems and optical security systems and has many advantages, such as high security level, convenience, flexibility, hyper extensibility, etc. This provides an interesting optical security technique for the protection of digital passwords.

  12. Optics Communications: Special issue on Polymer Photonics and Its Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing

    2016-03-01

    In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.

  13. Quantum ratchets for quantum communication with optical superlattices

    SciTech Connect

    Romero-Isart, Oriol; Garcia-Ripoll, Juan Jose

    2007-11-15

    We propose to use a quantum ratchet to transport quantum information in a chain of atoms trapped in an optical superlattice. The quantum ratchet is created by a continuous modulation of the optical superlattice which is periodic in time and in space. Though there is zero average force acting on the atoms, we show that indeed the ratchet effect permits atoms on even and odd sites to move along opposite directions. By loading the optical lattice with two-level bosonic atoms, this scheme permits us to perfectly transport a qubit or entangled state imprinted in one or more atoms to any desired position in the lattice. From the quantum computation point of view, the transport is achieved by a smooth concatenation of perfect swap gates. We analyze setups with noninteracting and interacting particles and in the latter case we use the tools of optimal control to design optimal modulations. We also discuss the feasibility of this method in current experiments.

  14. Communicating Uncertainties for Microwave-Based ESDRs

    NASA Astrophysics Data System (ADS)

    Wentz, F. J.; Mears, C. A.; Smith, D. K.

    2011-12-01

    Currently as part of NASA's MEaSUREs program, there is a 25-year archive of consistently-processed and carefully inter-calibrated Earth Science Data Records (ESDR) consisting of geophysical products derived from satellite microwave radiometers. These products include ocean surface temperature and wind speed, total atmospheric water vapor and cloud water, surface rain rate, and deep-layer averages of atmospheric temperature. The product retrievals are based on a radiative transfer model (RTM) for the surface and intervening atmosphere. Thus, the accuracy of the retrieved products depends both on the accuracy of the RTM, the accuracy of the measured brightness temperatures that serve as inputs to the retrieval algorithm, and on the accuracy of any ancillary data used to adjust for unmeasured geophysical conditions. In addition, for gridded products that are averages over time or space, sampling error can become important. It is important not only to calculate the uncertainties associated with the ESDRs but also to effectively communicate these uncertainties to the Users in a way that is helpful for their particular set of applications. This is a challenging task that will require a multi-faceted approach consisting of (1) error bars assigned to each retrieval, (2) detailed interactive validation reports, and (3) peer-reviewed scientific papers on long-term trends. All of this information needs to be linked to the ESDR's in a manner that facilitates integration into the User's applications. Our talk will discuss the progress we are making in implementing these approaches.

  15. Free-space optical communication links and evaporation layer study near sea surface at 1.55 μm

    NASA Astrophysics Data System (ADS)

    Zeller, John; Manzur, Tariq

    2011-06-01

    In many situations where it is necessary to set up a communication link such as emergencies or in remote locations, running fiber between two sites is not practical. Free-space optics (FSO) holds the potential for high bandwidth communication in such situations with relatively low cost, low maintenance, quick installation times, and average 70- 80% connectivity. Since atmospheric conditions can significantly affect the capability of this type of communication system to transfer information consistently and operate effectively, the effects of atmosphere on FSO communication and consequent optimal wavelength range for transmission are investigated through MODTRAN-based modeling of 1.55 μm transmission. Simulations were performed for multiple elevation angles in atmospheric weather conditions including clear maritime, desert extinction, and various levels of rain and fog to simulate surface-to-surface and surfaceto- air FSO communication networks. Atmospheric, free-space, and scintillation losses are analyzed for optical path lengths of up to 2 km or greater to determine minimum transmit power required for successful data reception. In addition, the effects of atmospheric turbulence on beam propagation in the evaporation layer are investigated, where wavefront sensing with adaptive optics as well as a software Kalman filter are seen as a means to compensate for wavefront distortion. Using advanced laser sources to provide illumination at infrared wavelengths, particularly around the eye-safe 1.55 μm wavelength, it should be possible to overcome many transmission limitations associated with atmospheric conditions such as adverse weather and turbulence to enable high data rate communication links where the use of fiber is not practical or prohibited.

  16. Novel space-time trellis codes for free-space optical communications using transmit laser selection.

    PubMed

    García-Zambrana, Antonio; Boluda-Ruiz, Rubén; Castillo-Vázquez, Carmen; Castillo-Vázquez, Beatriz

    2015-09-21

    In this paper, the deployment of novel space-time trellis codes (STTCs) with transmit laser selection (TLS) for free-space optical (FSO) communication systems using intensity modulation and direct detection (IM/DD) over atmospheric turbulence and misalignment fading channels is presented. Combining TLS and STTC with rate 1 bit/(s · Hz), a new code design criterion based on the use of the largest order statistics is here proposed for multiple-input/single-output (MISO) FSO systems in order to improve the diversity order gain by properly chosing the transmit lasers out of the available L lasers. Based on a pairwise error probability (PEP) analysis, closed-form asymptotic bit error-rate (BER) expressions in the range from low to high signal-to-noise ratio (SNR) are derived when the irradiance of the transmitted optical beam is susceptible to moderate-to-strong turbulence conditions, following a gamma-gamma (GG) distribution, and pointing error effects, following a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. Obtained results show diversity orders of 2L and 3L when simple two-state and four-state STTCs are considered, respectively. Simulation results are further demonstrated to confirm the analytical results. PMID:26406626

  17. Increasing the information rates of optical communications via coded modulation: a study of transceiver performance

    NASA Astrophysics Data System (ADS)

    Maher, Robert; Alvarado, Alex; Lavery, Domaniç; Bayvel, Polina

    2016-02-01

    Optical fibre underpins the global communications infrastructure and has experienced an astonishing evolution over the past four decades, with current commercial systems transmitting data rates in excess of 10 Tb/s over a single fibre core. The continuation of this dramatic growth in throughput has become constrained due to a power dependent nonlinear distortion arising from a phenomenon known as the Kerr effect. The mitigation of fibre nonlinearities is an area of intense research. However, even in the absence of nonlinear distortion, the practical limit on the transmission throughput of a single fibre core is dominated by the finite signal-to-noise ratio (SNR) afforded by current state-of-the-art coherent optical transceivers. Therefore, the key to maximising the number of information bits that can be reliably transmitted over a fibre channel hinges on the simultaneous optimisation of the modulation format and code rate, based on the SNR achieved at the receiver. In this work, we use an information theoretic approach based on the mutual information and the generalised mutual information to characterise a state-of-the-art dual polarisation m-ary quadrature amplitude modulation transceiver and subsequently apply this methodology to a 15-carrier super-channel to achieve the highest throughput (1.125 Tb/s) ever recorded using a single coherent receiver.

  18. Increasing the information rates of optical communications via coded modulation: a study of transceiver performance

    PubMed Central

    Maher, Robert; Alvarado, Alex; Lavery, Domaniç; Bayvel, Polina

    2016-01-01

    Optical fibre underpins the global communications infrastructure and has experienced an astonishing evolution over the past four decades, with current commercial systems transmitting data rates in excess of 10 Tb/s over a single fibre core. The continuation of this dramatic growth in throughput has become constrained due to a power dependent nonlinear distortion arising from a phenomenon known as the Kerr effect. The mitigation of fibre nonlinearities is an area of intense research. However, even in the absence of nonlinear distortion, the practical limit on the transmission throughput of a single fibre core is dominated by the finite signal-to-noise ratio (SNR) afforded by current state-of-the-art coherent optical transceivers. Therefore, the key to maximising the number of information bits that can be reliably transmitted over a fibre channel hinges on the simultaneous optimisation of the modulation format and code rate, based on the SNR achieved at the receiver. In this work, we use an information theoretic approach based on the mutual information and the generalised mutual information to characterise a state-of-the-art dual polarisation m-ary quadrature amplitude modulation transceiver and subsequently apply this methodology to a 15-carrier super-channel to achieve the highest throughput (1.125 Tb/s) ever recorded using a single coherent receiver. PMID:26864633

  19. Reduced electrical bandwidth receivers for direct detection 4-ary PPM optical communication intersatellite links

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic M.; Sun, Xiaoli

    1993-01-01

    One of the major sources of noise in a direct detection optical communication receiver is the shot noise due to the quantum nature of the photodetector. The shot noise is signal dependent and is neither Gaussian nor wide sense stationary. When a photomultiplier tube (PMT) or an avalanche photodiode (APD) is used, there is also a multiplicative excess noise due to the randomness of the internal photodetector gain. Generally speaking, the radio frequency (RF) communication theory cannot be applied to direct detection optical communication systems because noise in RF communication systems is usually additive and Gaussian. A receiver structure which is mathematically optimal for signal dependent shot noise is derived. Several suboptimal receiver structures are discussed and compared with the optimal receiver. The objective is to find a receiver structure which is easy to implement and gives close to optimal performance.

  20. Multichannel fiber optic broadband video communication system for monitoring CT/MR examinations

    NASA Astrophysics Data System (ADS)

    Huang, H. K.; Kangarloo, Hooshang; Tecotzky, Raymond H.; Cheng, Xin; Vanderweit, Don

    1991-05-01

    The Department of Radiological Sciences, UCLA operates five MR and four CT scanners located in three different buildings and two mobile sites. We have designed and implemented a multi-channel fiber optic broadband video communication system connecting these scanners together. This system consists of baseband fiber optic transmitters and receivers, a multiplexing headend, and broadband fiber optic transmitters and receivers. It can serve up to 5 km. The video signal from each scanner is sent through a baseband fiber optic link to the headend, where it is frequency modulated and distributed over broadband fiber optic links. A receiver, consisting of a demodulator, a TV monitor, and a channel selector, is placed at fourteen strategic locations including the fiber optic hub rooms, chest, neuroradiology, abdomen, bone, gastrointestinal, genitourinary, and pediatric reading rooms as well as scheduling rooms. A radiologist can use any of these fourteen receivers to view a patient''s CT/MR image in real time by selecting the proper channel assigned to the scanner, and use the telephone to communicate with the technologist to monitor the examination. This fiber optic broadband video communication system has been integrated into daily clinical use.