Design of compact off-axis four-mirror anastigmatic system for space communications

NASA Astrophysics Data System (ADS)

Zhao, Fa-cai; Sun, Quan-she; Chen, Kun-feng; Zhu, Xing-bang; Wang, Shao-shui; Wang, Guo-quan; Zheng, Xiang-liang

2013-08-01

The deployment of advanced hyperspectral imaging and other Earth sensing instruments onboard Earth observing satellites is driving the demand for high-data rate communications. Space laser communications technology offers the potential for significantly increasing in data return capability from space to Earth. Compared to the current state of the art radio frequency communications links, lasercom links operate at much higher carrier frequencies. The use of higher carrier frequencies implies a much smaller diffraction loss, which in turn, results in a much higher efficiency in delivering the signal energy. Optical communications meet the required data rates with small, low-mass, and low-power communications packages. The communications optical system assembly typically consists of a front aperture, reflection or refraction type telescope, with or without a solar rejection filter, aft optics, fine-pointing mirrors, and array detectors. Optical system used in space laser communications usually has long focal length, large aperture compared with common optical systems. So the reflective optical system is widely used. An unobstructed four-mirror anastigmatic telescope system was proposed, which was modified based on the theory about geometry optics of common-axis three-mirror systems. Intermediate image was between secondary and tertiary mirror. In order to fold the optical path, four-mirror was designed by adding the plane reflective mirror at intermediate image. The design was analyzed, then a system with effective aperture of 200mm and field of view of 1.0°x1.0° was designed, total length and magnification are 700mm and 20, respectively. The system has advantages of large magnification, relative short physical size and loose manufacturing tolerances.

Secure satellite communication using multi-photon tolerant quantum communication protocol

NASA Astrophysics Data System (ADS)

Darunkar, Bhagyashri; Punekar, Nikhil; Verma, Pramode K.

2015-09-01

This paper proposes and analyzes the potential of a multi-photon tolerant quantum communication protocol to secure satellite communication. For securing satellite communication, quantum cryptography is the only known unconditionally secure method. A number of recent experiments have shown feasibility of satellite-aided global quantum key distribution (QKD) using different methods such as: Use of entangled photon pairs, decoy state methods, and entanglement swapping. The use of single photon in these methods restricts the distance and speed over which quantum cryptography can be applied. Contemporary quantum cryptography protocols like the BB84 and its variants suffer from the limitation of reaching the distances of only Low Earth Orbit (LEO) at the data rates of few kilobits per second. This makes it impossible to develop a general satellite-based secure global communication network using the existing protocols. The method proposed in this paper allows secure communication at the heights of the Medium Earth Orbit (MEO) and Geosynchronous Earth Orbit (GEO) satellites. The benefits of the proposed method are two-fold: First it enables the realization of a secure global communication network based on satellites and second it provides unconditional security for satellite networks at GEO heights. The multi-photon approach discussed in this paper ameliorates the distance and speed issues associated with quantum cryptography through the use of contemporary laser communication (lasercom) devices. This approach can be seen as a step ahead towards global quantum communication.

Characterization and Design of Digital Pointing Subsystem for Optical Communication Demonstrator

NASA Technical Reports Server (NTRS)

Racho, C.; Portillo, A.

1998-01-01

The Optical Communications Demonstrator (OCD) is a laboratory-based lasercom demonstration terminal designed to validate several key technologies, including beacon acquisition, high bandwidth tracking, precision bearn pointing, and point-ahead compensation functions. It has been under active development over the past few years. The instrument uses a CCD array detector for both spatial acquisition and high-bandwidth tracking, and a fiber coupled laser transmitter. The array detector tracking concept provides wide field-of-view acquisition and permits effective platform jitter compensation and point-ahead control using only one steering mirror. This paper describes the detailed design and characterization of the digital control loop system which includes the Fast Steering Mirror (FSM), the CCD image tracker, and the associated electronics. The objective is to improve the overall system performance using laboratory measured data. The. design of the digital control loop is based on a linear time invariant open loop model. The closed loop performance is predicted using the theoretical model. With the digital filter programmed into the OCD control software, data is collected to verify the predictions. This paper presents the results of the, system modeling and performance analysis. It has been shown that measurement data closely matches theoretical predictions. An important part of the laser communication experiment is the ability of FSM to track the laser beacon within the. required tolerances. The pointing must be maintained to an accuracy that is much smaller than the transmit signal beamwidth. For an earth orbit distance, the system must be able to track the receiving station to within a few microradians. The failure. to do so will result in a severely degraded system performance.

INRRI-EDM/2016: the first laser retroreflector on the surface of Mars

NASA Astrophysics Data System (ADS)

Dell'Agnello, S.; Delle Monache, G.; Porcelli, L.; Boni, A.; Contessa, S.; Ciocci, E.; Martini, M.; Tibuzzi, M.; Intaglietta, N.; Salvatori, L.; Tuscano, P.; Patrizi, G.; Mondaini, C.; Lops, C.; Vittori, R.; Maiello, M.; Flamini, E.; Marchetti, E.; Bianco, G.; Mugnuolo, R.; Cantone, C.

2017-01-01

During Summer 2015 the SCF_Lab (Satellite/lunar/GNSS laser ranging/altimetry and cube/microsat Characterization Facilities Laboratory, http://www.lnf.infn.it/esperimenti/etrusco, Team of INFN-LNF, with support by ASI, carried out an intense activity of final design, manufacturing and testing in order to construct, space qualify and finally integrate INRRI-EDM/2016 on ESA's ExoMars EDM spacecraft (also dubbed "Schiaparelli"), which was successfully launched on March 14, 2016. INRRI (INstrument for landing-Roving laser Retroreflector Investigation) for the EDM (Entry descent and landing Demonstration Module) 2016 mission is a compact, lightweight, passive, maintenance-free array of eight cube corner laser retroreflectors fixed to an aluminum alloy frame through the use of silicon rubber suitable for space applications. INRRI was installed on the top panel of the EDM Central Bay on October 14, 2015. It will enable the EDM to be laser-located from Mars orbiters, through laser ranging and altimetry, lidar atmospheric observations from orbit, laser flashes emitted by orbiters, and lasercom. One or all of the above means of observation can be supported by INRRI when there is an active, laser-equipped orbiter, especially after EDM end-of-life and for a long time. INRRI goals will cover science (Mars geodesy/geophysics, future Mars test of General Relativity, GR), technology and exploration. Concerning the latter two, INRRI will support mars-georeferencing of the EDM landing site, support potential precision lidar-based landing next to the EDM, support test & diagnostics of lasercom for data exchange among Mars orbit, Mars surface and Earth, and it will be a precursor for additional Mars surface retroreflectors, for example on exploration rovers. This paper describes in detail our innovative payload, hopefully the very first to be deployed safely with the lander Schiaparelli on the Mars surface, and its space qualification for the ExoMars EDM 2016 mission. Despite the fate of the Schiaparelli landing, which is still under the investigation of ESA and the industry, this paper remains a valuable reference for next INRRI-like laser retroreflectors arrays.

Advanced Broadband Links for TIER III UAV Data Communication

NASA Astrophysics Data System (ADS)

Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kampfner, Hartmut

2011-08-01

Unmanned Aeronautical Vehicle (UAV) are getting more and more importance because of their prominent role as national reconnaissance systems, for disaster monitoring, and environmental mapping. However, the existence of reliable and robust data links are indispensable for Unmanned Aircraft System (UAS) missions. In particular for Beyond Line-Of-Sight operations (BLOS) of Tier III UAVs, satellite data links are a key element since extensive sensor data have to be transmitted preferably in real-time or near real-time.The paper demonstrates that the continuously increasing number of UAS and the intensified use of high resolution sensors will reveal RF-bandwidth as a limitating factor in the communication chain of Tier III UAVs. The RF-bandwidth gap can be partly closed by use of high-order modulation, of course, but much more progress in terms of bandwidth allocation can be achieved by using optical transmission technology. Consequently, the paper underlines that meanwhile this technology has been sufficiently verified in space, and shows that optical links are suited as well for broadband communications of Tier III UAVs. Moreover, the advantages of LaserCom in UAV scenarios and its importance for Network Centric Warfare (NCW) as well as for Command, Control, Communications, Computers, Intelligens, Surveillance, and Reconnaissance (C4ISR) are emphasized. Numerous practical topics and design requirements, relevant for the establishment of optical links onboard of Tier III UAVs, are discussed.

Pointing and Tracking Concepts for Deep Space Missions

NASA Technical Reports Server (NTRS)

Alexander, J. W.; Lee, S.; Chen, C.

2000-01-01

This paper summarizes part of a FY1998 effort on the design and development of an optical communications (Opcomm) subsystem for the Advanced Deep Space System Development (ADSSD) Project. This study was funded by the JPL X2000 program to develop an optical communications (Opcomm) subsystem for use in future planetary missions. The goal of this development effort was aimed at providing prototype hardware with the capability of performing uplink, downlink, and ranging functions from deep space distances. Such a system was envisioned to support future deep space missions in the Outer Planets/Solar Probe (OPSP) mission set such as the Pluto express and Europa orbiter by providing a significant enhancement of data return capability. A study effort was initiated to develop a flyable engineering model optical terminal to support the proposed Europa Orbiter mission - as either the prime telecom subsystem or for mission augmentation. The design concept was to extend the prototype lasercom terminal development effort currently conducted by JPL's Optical Communications Group. The subsystem would track the sun illuminated Earth at Europa and farther distances for pointing reference. During the course of the study, a number of challenging issues were found. These included thermo-mechanical distortion, straylight control, and pointing. This paper focuses on the pointing aspects required to locate and direct a laser beam from a spacecraft (S/C) near Jupiter to a receiving station on Earth.

Demonstration of Lasercom and Spatial Tracking with a Silicon Geiger-Mode APD Array

DTIC Science & Technology

2016-02-26

standardized pixel mask as described in the previous paragraph disabling 167 of the 1024 detectors in the array , this gives an absolute maximum rate...number of elements in an array based detector .5 In this paper, we present the results of photon-counting communication tests based on an arrayed ...semiconductor photon-counting detector .6 The array also has the ability to sense the spatial distribution of the received light giving it the potential to act

SBIR Technology Applications to Space Communications and Navigation (SCaN)

NASA Technical Reports Server (NTRS)

Liebrecht, Phil; Eblen, Pat; Rush, John; Tzinis, Irene

2010-01-01

This slide presentation reviews the mission of the Space Communications and Navigation (SCaN) Office with particular emphasis on opportunities for technology development with SBIR companies. The SCaN office manages NASA's space communications and navigation networks: the Near Earth Network (NEN), the Space Network (SN), and the Deep Space Network (DSN). The SCaN networks nodes are shown on a world wide map and the networks are described. Two types of technologies are described: Pull technology, and Push technologies. A listing of technology themes is presented, with a discussion on Software defined Radios, Optical Communications Technology, and Lunar Lasercom Space Terminal (LLST). Other technologies that are being investigated are some Game Changing Technologies (GCT) i.e., technologies that offer the potential for improving comm. or nav. performance to the point that radical new mission objectives are possible, such as Superconducting Quantum Interference Filters, Silicon Nanowire Optical Detectors, and Auto-Configuring Cognitive Communications

Multi-aperture digital coherent combining for free-space optical communication receivers.

PubMed

Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

2016-06-13

Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

Critical issues in assuring long lifetime and fail-safe operation of optical communications network

NASA Astrophysics Data System (ADS)

Paul, Dilip K.

1993-09-01

Major factors in assuring long lifetime and fail-safe operation in optical communications networks are reviewed in this paper. Reliable functionality to design specifications, complexity of implementation, and cost are the most critical issues. As economics is the driving force to set the goals as well as priorities for the design, development, safe operation, and maintenance schedules of reliable networks, a balance is sought between the degree of reliability enhancement, cost, and acceptable outage of services. Protecting both the link and the network with high reliability components, hardware duplication, and diversity routing can ensure the best network availability. Case examples include both fiber optic and lasercom systems. Also, the state-of-the-art reliability of photonics in space environment is presented.

Grating-based real-time smart optics for biomedicine and communications

NASA Astrophysics Data System (ADS)

Yaqoob, Zahid

Novel photonic systems are proposed and experimentally validated using active as well as passive wavelength dispersive optical devices in unique fashions to solve important system level application problems in biomedicine and laser communications. Specifically for the first time are proposed, high dynamic range variable optical attenuators (VOAs) using bulk acousto-optics (AO). These AO-based architectures have excellent characteristics such as high laser damage threshold (e.g., 1 Watt CW laser power operations), large (e.g., >40 dB) dynamic range, and microsecond domain attenuation setting speed. The demonstrated architectures show potentials for compact, low static insertion loss, and low power VOA designs for wavelength division multiplexed (WDM) fiber-optic communication networks and high speed photonic signal processing for optical and radio frequency (RF) radar and electronic warfare (EW). Acoustic diffraction of light in isotropic media has been manipulated to design and demonstrate on a proof-of-principle basis, the first bulk AO-based optical coherence tomography (OCT) system for high-resolution sub-surface tissue diagnostics. As opposed to the current OCT systems that use mechanical means to generate optical delays, both free-space as well as fiber-optic AO-based OCT systems utilize unique electronically-controlled acousto-optically switched no-moving parts optical delay lines and therefore promise microsecond speed OCT data acquisition rates. The proposed OCT systems also feature high (e.g., >100 MHz) intermediate frequency for low 1/f noise heterodyne detection. For the first time, two agile laser beam steering schemes that are members of a new beam steering technology known as Multiplexed-Optical Scanner Technology (MOST) are theoretically investigated and experimentally demonstrated. The new scanner technologies are based on wavelength and space manipulations and possess remarkable features such as a no-moving parts fast (e.g., microseconds domain or less) beam switching speed option, large (e.g., several centimeters) scanner apertures for high-resolution scans, and large (e.g., >10°) angular scans in more than one dimensions. These incredible features make these scanners excellent candidates for high-end applications. Specifically discussed and experimentally analyzed for the first time are novel MOST-based systems for agile free-space lasercom links, internal and external cavity scanning biomedical probes, and high-speed optical data handling such as barcode scanners. In addition, a novel low sidelobe wavelength selection filter based on a single bulk crystal acousto-optic tunable filter device is theoretically analyzed and experimentally demonstrated showing its versatility as a scanner control fiber-optic component for interfacing with the proposed wavelength based optical scanners. In conclusion, this thesis has shown how powerful photonic systems can be realized via novel architectures using active and passive wavelength sensitive optics leading to advanced solutions for the biomedical and laser communications research communities.

Telecom and scintillation first data analysis for DOMINO: laser communication between SOTA, onboard SOCRATES satellite, and MEO optical ground station

NASA Astrophysics Data System (ADS)

Phung, D.-H.; Samain, E.; Maurice, N.; Albanesse, D.; Mariey, H.; Aimar, M.; M. Lagarde, G.; Artaud, G.; Issler, J.-L.; Vedrenne, N.; Velluet, M.-T.; Toyoshima, M.; Akioka, M.; Kolev, D.; Munemasa, Y.; Takenaka, H.; Iwakiri, N.

2016-03-01

In collaboration between CNES, NICT, Geoazur, the first successful lasercom link between the micro-satellite SOCRATES and an OGS in Europe has been established. This paper presents some results of telecom and scintillation first data analysis for 4 successful links in June & July 2015 between SOTA terminal and MEO optical ground station (OGS) at Caussols France. The telecom and scintillation data have been continuously recorded during the passes by using a detector developed at the laboratory. An irradiance of 190 nW/m2 and 430 nW/m2 has been detected for 1549 nm and 976 nm downlinks at 35° elevation. Spectrums of power fluctuation measured at OGS are analyzed at different elevation angles and at different diameters of telescope aperture to determine fluctuations caused by pointing error (due to satellite & OGS telescope vibrations) and caused by atmospheric turbulence. Downlink & Uplink budgets are analyzed, the theoretical estimation matches well to measured power levels. Telecom signal forms and bit error rates (BER) of 1549 nm and 976 nm downlink are also shown at different diameters of telescope aperture. BER is 'Error Free' with full-aperture 1.5m telescope, and almost in `good channel' with 0.4 m sub-aperture of telescope. We also show the comparison between the expected and measured BER distributions.

Receiver Architecture for 12.5 Gb/s 16-ary Pulse Position Modulation (PPM) Signaling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendez, A J; Gagliardi, R M; Hernandez, V J

2008-07-11

PPM is a signaling scheme that enables the transmission of multiple bits per symbol [1]. It has found favor in the regime of free space optical communications ('FSO' or 'Lasercom'); however, PPM has yet to be widely applied to fiber optic-based communications. Its limitation in fiber results from the exceedingly high bandwidth requirements needed to electronically process a directly detected pulse, especially as the symbol rate increases and the pulse width correspondingly decreases. As a solution, we introduced the concept of a virtual quadrant receiver for receiving 1.25 Gb/s 4-ary PPM, where photonic processing reduced the number of required electronicmore » components [2]. In this paper, we extend these photonic process techniques to a 16-ary, 12.5 Gb/s (10 Gb/s plus 8B/10B line coding) PPM communications system for fiber optic avionics, wherein much of the receiver processing is enabled by techniques based on planar lightwave circuits (PLCs). The architecture is applicable to higher input data rates and M-ary PPM. In the following, we present the PPM encoding and decoding architectures and numerically simulated results.« less

LEO-to-ground optical communications using SOTA (Small Optical TrAnsponder) - Payload verification results and experiments on space quantum communications

NASA Astrophysics Data System (ADS)

Carrasco-Casado, Alberto; Takenaka, Hideki; Kolev, Dimitar; Munemasa, Yasushi; Kunimori, Hiroo; Suzuki, Kenji; Fuse, Tetsuharu; Kubo-Oka, Toshihiro; Akioka, Maki; Koyama, Yoshisada; Toyoshima, Morio

2017-10-01

Free-space optical communications have held the promise of revolutionizing space communications for a long time. The benefits of increasing the bitrate while reducing the volume, mass and energy of the space terminals have attracted the attention of many researchers for a long time. In the last few years, more and more technology demonstrations have been taking place with participants from both the public and the private sector. The National Institute of Information and Communications Technology (NICT) in Japan has a long experience in this field. SOTA (Small Optical TrAnsponder) was the last NICT space lasercom mission, designed to demonstrate the potential of this technology applied to microsatellites. Since the beginning of SOTA mission in 2014, NICT regularly established communication using the Optical Ground Stations (OGS) located in the Headquarters at Koganei (Tokyo) to receive the SOTA signals, with over one hundred successful links. All the goals of the SOTA mission were fulfilled, including up to 10-Mbit/s downlinks using two different wavelengths and apertures, coarse and fine tracking of the OGS beacon, space-to-ground transmission of the on-board-camera images, experiments with different error correcting codes, interoperability with other international OGS, and experiments on quantum communications. The SOTA mission ended on November 2016, more than doubling the designed lifetime of 1-year. In this paper, the SOTA characteristics and basic operation are explained, along with the most relevant technological demonstrations.

Nanosatellite optical downlink experiment: design, simulation, and prototyping

NASA Astrophysics Data System (ADS)

Clements, Emily; Aniceto, Raichelle; Barnes, Derek; Caplan, David; Clark, James; Portillo, Iñigo del; Haughwout, Christian; Khatsenko, Maxim; Kingsbury, Ryan; Lee, Myron; Morgan, Rachel; Twichell, Jonathan; Riesing, Kathleen; Yoon, Hyosang; Ziegler, Caleb; Cahoy, Kerri

2016-11-01

The nanosatellite optical downlink experiment (NODE) implements a free-space optical communications (lasercom) capability on a CubeSat platform that can support low earth orbit (LEO) to ground downlink rates>10 Mbps. A primary goal of NODE is to leverage commercially available technologies to provide a scalable and cost-effective alternative to radio-frequency-based communications. The NODE transmitter uses a 200-mW 1550-nm master-oscillator power-amplifier design using power-efficient M-ary pulse position modulation. To facilitate pointing the 0.12-deg downlink beam, NODE augments spacecraft body pointing with a microelectromechanical fast steering mirror (FSM) and uses an 850-nm uplink beacon to an onboard CCD camera. The 30-cm aperture ground telescope uses an infrared camera and FSM for tracking to an avalanche photodiode detector-based receiver. Here, we describe our approach to transition prototype transmitter and receiver designs to a full end-to-end CubeSat-scale system. This includes link budget refinement, drive electronics miniaturization, packaging reduction, improvements to pointing and attitude estimation, implementation of modulation, coding, and interleaving, and ground station receiver design. We capture trades and technology development needs and outline plans for integrated system ground testing.

Task five report: Laser communications for data acquisition networks. [characteristics of lasers and laser systems for optical communication applications

NASA Technical Reports Server (NTRS)

1973-01-01

Laser communication technology and laser communication performance are reviewed. The subjects discussed are: (1) characteristics of laser communication systems, (2) laser technology problems, (3) means of overcoming laser technology problems, and (4) potential schedule for including laser communications into data acquisition networks. Various types of laser communication systems are described and their capabilities are defined.

Large Diameter, High Speed InGaAs Receivers for Free-Space Lasercom

DTIC Science & Technology

2007-01-01

appropriate transimpedance amplifier and limiting amplifier . Development and testing of the APD receivers will be described below. 15. SUBJECT TERMS 16...available transimpedance amplifiers (TIA) from Maxim of Dallas. There have also been several devices built in house by NRL in 8-pin TO-39 headers...manufacture a large area, high speed InGaAs APD with an effective ionization ratio of < 0.2 and by matching the APD device with an appropriate transimpedance

Free-space laser communication technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 11, 12, 1988

NASA Astrophysics Data System (ADS)

Koepf, Gerhard A.; Begley, David L.

1988-01-01

The present conference discusses topics in free-space laser communications, laser link characteristics, satellite laser communication systems, optoelectronic components for laser communications, and space laser subsystem technologies. Attention is given to Space Station-based deep-space communication experiments, the application of intersatellite links to operational satellite systems, high-power 0.87 micron channel substrate planar lasers for spaceborne communications, a ground experiment using a CO2 laser transceiver for free-space communications, studies of laser ranging to the TOPEX satellite, diffraction-limited tracking for space communications, and the compact implementation of a real-time, acoustooptic SAR processor.

Novel packaging approaches for increased robustness and overall performance of gimbal-less MEMS mirrors

NASA Astrophysics Data System (ADS)

Milanović, Veljko; Kasturi, Abhishek; Yang, James; Su, Yu Roger; Hu, Frank

2017-02-01

2D quasistatic (point-to-point) gimbal-less MEMS mirrors enable programmable, arbitrary control of laser beam position and velocity - up to their maximum limits. Hence, they provide the ability to track targets, point lasercom beams, and to scan uniform velocity lines over objects in laser imaging. They are becoming increasingly established in applications including 3D scanning, laser marking and 3D printing, biomedical imaging, communications, and LiDAR. With the increased utility in applications that demand larger mirror sizes and larger overall angle*diameter (θ*D) figures of merit, the technology is continuously pushed against its limit. As a result we have implemented mirrors with larger diameters including 5.0mm, 6.4mm, and 7.5mm, and have designed actuators with larger torque and angles to match the Θ*D demand. While the results have been very positive in certain application cases, a limitation for their more wide-spread use has been the relatively high susceptibility of large- θ*D mirrors to shock and vibrations. On the other hand, one of the challenges of MEMS mirrors of small diameters is their lower optical power tolerance simply due to their smaller area and heat removal ability. Although they can be operated at up to 2-3W of CW laser power, new developments in dynamic solid state lighting in e.g. headlights demand operation at up to 10W or beyond. In this work we study and present several package-level approaches to increase mechanical damping, shock robustness, and laser power tolerance. Specifically, we study back-filling of MEMS packages with different gases as well as with different (increased) pressures to control damping and in turn increase robustness and useable bandwidth. Additionally, we study the effects of specialized mechanical structures which were designed and fabricated to modify packages to significantly reduce volumes of space around moving structures. In their standard form and packaging the MEMS mirrors tested in this study typically measure quality factors of 75-100. Increases of pressure up to 50psi have shown relatively modest reductions of the overall quality factor to the 40-50 range. Backfilling of packages with heavier inert gasses such as Ar and SF6 results in lowering of the quality factor down to 20-30 range. Mechanical modifications of the package with special structures and reduced air-gap to the window yielded the best results, reducing the quality factor to 9-14. Combination of specialized packaging structures and gas backfill and pressure control could provide a very efficient heat transfer from the mirror and the desired near-critical damping, but has not been demonstrated yet. The increased performance does not change the compactness and low power consumption - the improved MEMS mirrors still consume <1mW. So far, designs with mirror sizes through 3.0mm diameter with increased damping have passed 500G shock tests. In terms of improved heat removal we have found that the packaging improvement greatly increased optical power tolerance of MEMS mirrors from few Watts of CW laser power to <10 Watts. The exact numbers for the upper limit are not yet available - in samples where the heat removing structure was added and air was replaced with Helium, our setup with 3 combined lasers was not able to damage any samples.

Research on key technology of space laser communication network

NASA Astrophysics Data System (ADS)

Chang, Chengwu; Huang, Huiming; Liu, Hongyang; Gao, Shenghua; Cheng, Liyu

2016-10-01

Since the 21st century, Spatial laser communication has made a breakthrough development. Europe, the United States, Japan and other space powers have carried out the test of spatial laser communication technology on-orbit, and put forward a series of plans. In 2011, China made the first technology demonstration of satellite-ground laser communication carried by HY-2 satellite. Nowadays, in order to improve the transmission rate of spatial network, the topic of spatial laser communication network is becoming a research hotspot at home and abroad. This thesis, from the basic problem of spatial laser communication network to solve, analyzes the main difference between spatial network and ground network, which draws forth the key technology of spatial laser communication backbone network, and systematically introduces our research on aggregation, addressing, architecture of spatial network. From the perspective of technology development status and trends, the thesis proposes the development route of spatial laser communication network in stages. So as to provide reference about the development of spatial laser communication network in China.

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.

Laser communication experiment. Volume 1: Design study report: Spacecraft transceiver. Part 1: Transceiver design

NASA Technical Reports Server (NTRS)

1970-01-01

The ATS-F Laser Communications Experiment (LCE) is the first significant step in the application of laser systems to space communications. The space-qualified laser communications system being developed in this experiment, and the data resulting from its successful deployment in space, will be applicable to the use of laser communications systems in a wide variety of manned as well as unmanned space missions, both near earth and in deep space. Particular future NASA missions which can benefit from this effort are the Tracking and Data Relay Satellite System and the Earth Resources Satellites. The LCE makes use of carbon dioxide lasers to establish simultaneous, two-way communication between the ATS-F synchronous satellite and a ground station. In addition, the LCE is designed to permit communication with a similar spacecraft transceiver proposed to be flown on ATS-G, nominally one year after the launch of ATS-F. This would be the first attempt to employ lasers for satellite-to-satellite communications.

Viterbi equalization for long-distance, high-speed underwater laser communication

NASA Astrophysics Data System (ADS)

Hu, Siqi; Mi, Le; Zhou, Tianhua; Chen, Weibiao

2017-07-01

In long-distance, high-speed underwater laser communication, because of the strong absorption and scattering processes, the laser pulse is stretched with the increase in communication distance and the decrease in water clarity. The maximum communication bandwidth is limited by laser-pulse stretching. Improving the communication rate increases the intersymbol interference (ISI). To reduce the effect of ISI, the Viterbi equalization (VE) algorithm is used to estimate the maximum-likelihood receiving sequence. The Monte Carlo method is used to simulate the stretching of the received laser pulse and the maximum communication rate at a wavelength of 532 nm in Jerlov IB and Jerlov II water channels with communication distances of 80, 100, and 130 m, respectively. The high-data rate communication performance for the VE and hard-decision algorithms is compared. The simulation results show that the VE algorithm can be used to reduce the ISI by selecting the minimum error path. The trade-off between the high-data rate communication performance and minor bit-error rate performance loss makes VE a promising option for applications in long-distance, high-speed underwater laser communication systems.

Research on large-aperture primary mirror supporting way of vehicle-mounted laser communication system

NASA Astrophysics Data System (ADS)

Meng, Lixin; Meng, Lingchen; Zhang, Yiqun; Zhang, Lizhong; Liu, Ming; Li, Xiaoming

2018-01-01

In the satellite to earth laser communication link, large-aperture ground laser communication terminals usually are used in order to realize the requirement of high rate and long distance communication and restrain the power fluctuation by atmospheric scintillation. With the increasing of the laser communication terminal caliber, the primary mirror weight should also be increased, and selfweight, thermal deformation and environment will affect the surface accuracy of the primary mirror surface. A high precision vehicular laser communication telescope unit with an effective aperture of 600mm was considered in this paper. The primary mirror is positioned with center hole, which back is supported by 9 floats and the side is supported by a mercury band. The secondary mirror adopts a spherical adjusting mechanism. Through simulation analysis, the system wave difference is better than λ/20 when the primary mirror is in different dip angle, which meets the requirements of laser communication.

Laser Communication Demonstration System (LSCS) and Future Mobile Satellite Services

NASA Technical Reports Server (NTRS)

Chen, C. -C.; Lesh, J. R.

1995-01-01

The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth Orbit. For future global satellite communication systems using intersatellite links (ISLs), laser communications technology can offer reduced mass , reduced power requirements, and increased channel bandwidths without regulatory restraint. This paper provides comparisons with radio systems and status of the program.

Airborne space laser communication system and experiments

NASA Astrophysics Data System (ADS)

Li, Xiao-Ming; Zhang, Li-zhong; Meng, Li-Xin

2015-11-01

Airborne space laser communication is characterized by its high speed, anti-electromagnetic interference, security, easy to assign. It has broad application in the areas of integrated space-ground communication networking, military communication, anti-electromagnetic communication. This paper introduce the component and APT system of the airborne laser communication system design by Changchun university of science and technology base on characteristic of airborne laser communication and Y12 plan, especially introduce the high communication speed and long distance communication experiment of the system that among two Y12 plans. In the experiment got the aim that the max communication distance 144Km, error 10-6 2.5Gbps - 10-7 1.5Gbps capture probability 97%, average capture time 20s. The experiment proving the adaptability of the APT and the high speed long distance communication.

ISS Efforts to Fully Utilize its Target Acquisition Capability Serves as an Analog for Future Laser Pointing Communications Systems

NASA Technical Reports Server (NTRS)

Jackson, Dan

2017-01-01

The ISS is an outstanding platform for developing, testing and refining laser communications systems for future exploration. A recent ISS project which improved ISS communications satellite acquisition performance proves the platform’s utility as a laser communications systems testbed.

Laser Experiments with ARTEMIS Satellite in Cloudy Conditions

NASA Astrophysics Data System (ADS)

Kuzkov, Volodymyr; Sodnik, Zoran; Kuzkov, Sergii; Caramia, Vincenzo

2014-05-01

In July 2001, the ARTEMIS satellite with laser communication terminal OPALE on board was launched. 1789 laser communications sessions were performed between ARTEMIS and SPOT-4 (PASTEL) from 01 April 2003 to 09 January 2008 with total duration of 378 hours. In addition ESA's Optical Ground Station (OGS) performed laser communication experiments with OPALE in various atmospheric conditions. Since the launch of ARTEMIS, the amount of information handled by geostationary telecommunication satellites has increased dramatically and so has the demand for data rate that needs to be transmitted from ground. With limited bandwidth allocations in the radio frequency bands interest has grown for laser communication feeder link technology. In this respect there is interest to compare the influence of atmosphere conditions in different atmospheric regions with respect to laser transmission. Two locations are being compared, namely ESA's OGS (located in an altitude of 2400 m above sea level) and the Main Astronomical Observatory of Ukraine (MAO) (located at an altitude of 190 m above sea level). In 2002 MAO started the development of a ground laser communication system for the AZT-2 telescope. The MAO developed compact laser communication system is called LACES (Laser Atmosphere and Communication Experiments with Satellites) [1] and the work was supported by the National Space Agency of Ukraine and by ESA. The beacon laser from OPALE was occasionally detected even in cloudy conditions and an anomalous atmospheric refraction at low elevation angles was observed. The main results of laser experiments with ARTEMIS through clouds are presented in the paper.

Laser Communication Experiments with Artemis Satellite

NASA Astrophysics Data System (ADS)

Kuzkov, Sergii; Sodnik, Zoran; Kuzkov, Volodymyr

2013-10-01

In November 2001, the European Space Agency (ESA) established the world-first inter-satellite laser communication link between the geostationary ARTEMIS satellite and the low Earth orbiting (LEO) SPOT-4 Earth observation satellite, demonstrating data rates of 50 Mbps. In 2006, the Japanese Space Agency launched the KIRARI (OICETS) LEO satellite with a compatible laser communication terminal and bidirectional laser communication links (50 Mbps and 2 Mbps) were successfully realized between KIRARI and ARTEMIS. ESA is now developing the European Data Relay Satellite (EDRS) system, which will use laser communication technology to transmit data between the Sentinel 1 and 2 satellites in LEO to two geostationary satellites (EDRS-A and EDRS-C) at data rates of 1.8 Gbps. As the data handling capabilities of state-of-the-art telecommunication satellites in GEO increase so is the demand for the feeder-link bandwidth to be transmitted from ground. This is why there is an increasing interest in developing high bandwidth ground-to-space laser communication systems working through atmosphere. In 2002, the Main Astronomical Observatory (MAO) started the development of its own laser communication system for its 0.7m AZT-2 telescope, located in Kyiv, Ukraine. The work was supported by the National Space Agency of Ukraine and by ESA. MAO developed a highly accurate computerized tracking system for AZT-2 telescope and a compact laser communication package called LACES (Laser Atmosphere and Communication Experiments with Satellites). The LACES instrument includes a camera of the pointing and tracking subsystems, a receiver module, a laser transmitter module, a tip/tilt atmospheric turbulence compensation subsystem, a bit error rate tester module and other optical and electronic components. The principal subsystems are mounted on a platform, which is located at the Cassegrain focus of the AZT-2 telescope. All systems were tested with the laser communication payload on-board ARTEMIS and the data analysis was supported by the telemetry received from the ARTEMIS payload control centre in Redu (Belgium). Special attention was focused on the investigation of the impact of atmosphere turbulence on laser beam propagation, especially in cloudy conditions. A description of our telescope and ground based laser system as well as the experimental results will be presented.

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;…

Laser communications through the atmosphere

NASA Technical Reports Server (NTRS)

Shaik, Kamran; Churnside, J. H.

1988-01-01

Atmospheric properties affecting laser propagation with reference to optical communications are reviewed. Some of the optical space network configurations and various diversity techniques that may need to be utilized to develop robust bi-directional space-earth laser communication links are explored.

Homodyne BPSK-based optical inter-satellite communication links

NASA Astrophysics Data System (ADS)

Lange, Robert; Smutny, Berry

2007-02-01

Summer 2007, Tesat will verify laser communication terminals based on homodyne BPSK (binary phase shift keying) in-orbit. A 5.625 Gbps LEO-LEO laser communication link, established between the German satellite TerraSAR-X and the US satellite NFIRE, shall demonstrate the performance and advantages of laser communication. End of 2006, a further program has been kicked-off to demonstrate the performance of ~2 Gbps LEO-GEO laser communication links. The link is part of a data relais from the German LEO satellite TanDEM-X via a Geo satellite to ground. The LEO-to-GEO laser commmunication link can be extended to further ~2 Gpbs GEO-GEO, and GEO-to-ground links.

A laser communication experiment utilizing the ACT satellite and an airborne laser transceiver

NASA Technical Reports Server (NTRS)

Provencher, Charles E., Jr.; Spence, Rodney L.

1988-01-01

The launch of a laser communication transmitter package into geosynchronous Earth orbit onboard the Advanced Communications Technology Satellite (ACTS) will present an excellent opportunity for the experimental reception of laser communication signals transmitted from a space orbit. The ACTS laser package includes both a heterodyne transmitter (Lincoln Labs design) and a direct detection transmitter (Goddard Space Flight Center design) with both sharing some common optical components. NASA Lewis Research Center's Space Electronics Division is planning to perform a space communication experiment utilizing the GSFC direct detection laser transceiver. The laser receiver will be installed within an aircraft provided with a glass port for the reception of the signal. This paper describes the experiment and the approach to performing such an experiment. Described are the constraints placed on the NASA Lewis experiment by the performance parameters of the laser transmitter and by the ACTS spacecraft operations. The conceptual design of the receiving terminal is given; also included is the anticipated capability of the detector.

Status of High Data Rate Intersatellite Laser Communication as an Enabler for Earth and Space Science

NASA Astrophysics Data System (ADS)

Heine, F.; Zech, H.; Motzigemba, M.

2017-12-01

Space based laser communication is supporting earth observation and science missions with Gbps data download capabilities. Currently the Sentinel 1 and Sentinel 2 spacecrafts from the Copernicus earth observation program of the European Commission are using the Gbps laser communication links developed by Tesat Spacecom to download low latency data products via a commercial geostationary laser relay station- the European Data Relay Service- (EDRS) as a standard data path, in parallel to the conventional radio frequency links. The paper reports on the status of high bandwidth space laser communication as an enabler for small and large space science missions ranging from cube sat applications in low earth orbit to deep space missions. Space based laser communication has left the experimental phase and will support space science missions with unprecedented data rates.

Laser communication experiment. Volume 1: Design study report: Spacecraft transceiver. Part 3: LCE design specifications

NASA Technical Reports Server (NTRS)

1970-01-01

The requirements for the design, fabrication, performance, and testing of a 10.6 micron optical heterodyne receiver subsystem for use in a laser communication system are presented. The receiver subsystem, as a part of the laser communication experiment operates in the ATS 6 satellite and in a transportable ground station establishing two-way laser communications between the spacecraft and the transportable ground station. The conditions under which environmental tests are conducted are reported.

Evaluation of the communication quality of free-space laser communication based on the power-in-the-bucket method.

PubMed

Yin, Xianghui; Wang, Rui; Wang, Shaoxin; Wang, Yukun; Jin, Chengbin; Cao, Zhaoliang; Xuan, Li

2018-02-01

Atmospheric turbulence seriously affects the quality of free-space laser communication. The Strehl ratio (SR) is used to evaluate the effect of atmospheric turbulence on the receiving energy of free-space laser communication systems. However, the SR method does not consider the area of the laser-receiving end face. In this study, the power-in-the-bucket (PIB) method is demonstrated to accurately evaluate the effect of turbulence on the receiving energy. A theoretical equation is first obtained to calculate PIB. Simulated and experimental validations are then performed to verify the effectiveness of the theoretical equation. This work may provide effective guidance for the design and evaluation of free-space laser communication systems.

Research on the method of precise alignment technology of atmospheric laser communication

NASA Astrophysics Data System (ADS)

Chen, Wen-jian; Gao, Wei; Duan, Yuan-yuan; Ma, Shi-wei; Chen, Jian

2016-10-01

Atmosphere laser communication takes advantage of laser as the carrier transmitting the voice, data, and image information in the atmosphere. Because of its high reliability, strong anti-interference ability, the advantages of easy installation, it has great potential and development space in the communications field. In the process of establish communication, the capture, targeting and tracking of the communication signal is the key technology. This paper introduce a method of targeting the signal spot in the process of atmosphere laser communication, which through the way of making analog signal addition and subtraction directly and normalized to obtain the target azimuth information to drive the servo system to achieve precise alignment of tracking.

Laser Ground System for Communication Experiments with ARTEMIS

NASA Astrophysics Data System (ADS)

Kuzkov, Volodymyr; Volovyk, Dmytro; Kuzkov, Sergii; Sodnik, Zoran; Pukha, Sergii; Caramia, Vincenzo

2012-10-01

The ARTEMIS satellite with the OPALE laser communication terminal on-board was launched on 12 July, 2001. 1789 laser communications sessions were performed between ARTEMIS and SPOT-4 (PASTEL) from 01 April 2003 to 09 January 2008 with total duration of 378 hours. Regular laser communication experiments between ESA's Optical Ground Station (OGS - altitude 2400 m above see level) and ARTEMIS in various atmosphere conditions were also performed. The Japanese Space Agency (JAXA) launched the KIRARI (OICETS) satellite with laser communication terminal called LUCE. Laser communication links between KIRARI and ARTEMIS were successfully realized and international laser communications experiments from the KIRARI satellite were also successfully performed with optical ground stations located in the USA (JPL), Spain (ESA OGS), Germany (DLR), and Japan (NICT). The German Space Agency (DLR) performed laser communication links between two LEO satellites (TerraSAR-X and NFIRE), demonstrating data transfer rates of 5.6Gbit/s and performed laser communication experiments between the satellites and the ESA optical ground station. To reduce the influence of weather conditions on laser communication between satellites and ground stations, a network of optical stations situated in different atmosphere regions needs to be created. In 2002, the Main Astronomical Observatory (MAO) started the development of its own laser communication system to be placed into the Cassegrain focus of its 0.7m AZT-2 telescope (Fe = 10.5m), located in Kyiv 190 meters above sea level. The work was supported by the National Space Agency of Ukraine and by ESA ARTEMIS has an orbital position of 21.4° E and an orbital inclination of more than 9.75°. As a result we developed a precise tracking system for AZT-2 telescope (weighing more than 2 tons) using micro-step motors. Software was developed for computer control of the telescope to track the satellite's orbit and a tracking accuracy of 0.6 arcsec was achieved. A compact terminal for Laser Atmosphere and Communication Experiments with Satellite (LACES) has been produced. The LACES terminal includes: A CMOS camera of the pointing subsystem, a CCD camera of the tracking subsystem, an avalanche photodiode receiver module with thermoelectric cooling, a laser transmitter module with thermoelectric temperature control, a tip/tilt atmospheric turbulence compensation subsystem with movable mirrors, a four-quadrant photo-detector, a bit error rate tester module and other optical and electronic components. The principal subsystems and optical elements are mounted on a platform (weight < 20kg), which is located in the Cassegrain focus of the telescope. All systems were tested with ARTEMIS. The telemetry and dump buffer information from OPALE received by the control center in Redu (Belgium) was analyzed. During the beacon scan, the acquisition phase of laser link between OPALE laser terminal of ARTEMIS and LACES laser terminal started and laser signals from AZT-2 were detected by acquisition and tracking CCD sensors of OPALE. Some of the tests were performed in cloudy conditions. A description of our laser ground system and the experimental results will be presented in the report.

Undersea Laser Communication with Narrow Beams

DTIC Science & Technology

2015-09-29

Abstract Laser sources enable highly efficient optical communications links due to their ability to be focused into very directive beam profiles...Recent atmospheric and space optical links have demonstrated robust laser communications links at high rate with techniques that are applicable to the...undersea environment. These techniques contrast to the broad-angle beams utilized in most reported demonstrations of undersea optical communications

Laser Communication Demonstration System (LCDS) and future mobile satellite services

NASA Technical Reports Server (NTRS)

Chen, Chien-Chung; Wilhelm, Michael D.; Lesh, James R.

1995-01-01

The Laser Communications Demonstration System (LCDS) is a proposed in-orbit demonstration of high data rate laser communications technology conceived jointly by NASA and U.S. industry. The program objectives are to stimulate industry development and to demonstrate the readiness of high data rate optical communications in Earth orbit. For future global satellite communication systems using intersatellite links, laser communications technology can offer reduced mass and power requirements and higher channel bandwidths without regulatory constraints. As currently envisioned, LCDS will consist of one or two orbiting laser communications terminals capable of demonstrating high data rate (greater than 750Mbps) transmission in a dynamic space environment. Two study teams led by Motorola and Ball Aerospace are currently in the process of conducting a Phase A/B mission definition study of LCDS under contracts with JPL/NASA. The studies consist of future application survey, concept and requirements definition, and a point design of the laser communications flight demonstration. It is planned that a single demonstration system will be developed based on the study results. The Phase A/B study is expected to be completed by the coming June, and the current results of the study are presented in this paper.

Laser diode technology for coherent communications

NASA Technical Reports Server (NTRS)

Channin, D. J.; Palfrey, S. L.; Toda, M.

1989-01-01

The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

Free-space laser communication technologies IV; Proceedings of the 4th Conference, Los Angeles, CA, Jan. 23, 24, 1992

NASA Technical Reports Server (NTRS)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1992-01-01

Papers included in this volume are grouped under topics of receivers; laser transmitters; components; system analysis, performance, and applications; and beam control (pointing, acquisition, and tracking). Papers are presented on an experimental determination of power penalty contributions in an optical Costas-type phase-locked loop receiver, a resonant laser receiver for free-space laser communications, a simple low-loss technique for frequency-locking lasers, direct phase modulation of laser diodes, and a silex beacon. Particular attention is given to experimental results on an optical array antenna for nonmechanical beam steering, a potassium Faraday anomalous dispersion optical filter, a 100-Mbps resonant cavity phase modulator for coherent optical communications, a numerical simulation of a 325-Mbit/s QPPM optical communication system, design options for an optical multiple-access data relay terminal, CCD-based optical tracking loop design trades, and an analysis of a spatial-tracking subsystem for optical communications.

Laser communication experiment. Volume 1: Design study report: Spacecraft transceiver. Part 2: Appendices

NASA Technical Reports Server (NTRS)

1970-01-01

The application of a carbon dioxide laser for optical communication with ATS satellites is discussed. The following elements of the laser communication equipment are reported: (1) operational ground equipment, (2) data acquisition plan, and (3) data processing, reduction, and analysis plan.

Coupling efficiency of laser beam to multimode fiber for free space optical communication

NASA Astrophysics Data System (ADS)

Arisa, Suguru; Takayama, Yoshihisa; Endo, Hiroyuki; Shimizu, Ryosuke; Fujiwara, Mikio; Sasaki, Masahide

2017-11-01

Recently, the free space optical (FSO) communications have been widely studied as an alternative for large capacity communications and its possible implementation in satellite and terrestrial laser links. In satellite communications, clouds can strongly attenuate the laser signal that would lead to high bit-error rates or temporal unavailability of the link. To overcome the cloud coverage effects, often site diversity technique is implemented. When using multiple ground stations though, simplified optical system is required to allow the usage of more flexible approaches. In terrestrial laser communications, several methods for optical system simplification by using a multimode fiber (MMF) have been proposed.

A Combined Laser-Communication and Imager for Microspacecraft (ACLAIM)

NASA Technical Reports Server (NTRS)

Hemmati, H.; Lesh, J.

1998-01-01

ACLAIM is a multi-function instrument consisting of a laser communication terminal and an imaging camera that share a common telescope. A single APS- (Active Pixel Sensor) based focal-plane-array is used to perform both the acquisition and tracking (for laser communication) and science imaging functions.

The quick acquisition technique for laser communication between LEO and GEO

NASA Astrophysics Data System (ADS)

Zhang, Li-zhong; Zhang, Rui-qin; Li, Yong-hao; Meng, Li-xin; Li, Xiao-ming

2013-08-01

The sight-axis alignment can be accomplished by the quick acquisition operation between two laser communication terminals, which is the premise of establishing a free-space optical communication link. Especially for the laser communication links of LEO (Low Earth Orbit)-Ground and LEO-GEO (Geostationary Earth Orbit), since the earth would break the transmission of laser and break the communication as well, so the effective time for each communication is very shot (several minutes~ dozens of minutes), as a result the communication terminals have to capture each other to rebuild the laser communication link. In the paper, on the basis of the analysis of the traditional methods, it presents a new idea that using the long beacon light instead of the circular beacon light; thereby the original of two-dimensional raster spiral scanning is replaced by one-dimensional scanning. This method will reduce the setup time and decrease the failure probability of acquisition for the LEO-GEO laser communication link. Firstly, the analysis of the external constraint conditions in the acquisition phase has been presented in this paper. Furthermore, the acquisition algorithm models have been established. The optimization analysis for the parameters of the acquisition unit has been carried out, and the ground validation experiments of the acquisition strategy have also been performed. The experiments and analysis show that compared with traditional capturing methods, the method presented in this article can make the capturing time be shortened by about 40%, and the failure probability of capturing be reduced by about 30%. So, the method is significant for the LEO-GEO laser communication link.

Mars Laser Communication Demonstration, Artist's Concept

NASA Technical Reports Server (NTRS)

2005-01-01

This illustration depicts a concept for operation of an optical communications system on NASA's Mars Telecommunications Orbiter. The orbiter is in development for launch in September 2009 with a payload including the spacecraft terminal of the Mars Laser Communication Demonstration Project. This project will also include an Earth-based terminal for two-way, high-data-rate communication using infrared light. The orbiter's primary communications with Earth will use radio frequencies. The laser demonstration is intended to build experience for use in decisions about possible use of optical communications by later missions.

Bidirectional chaos communication between two outer semiconductor lasers coupled mutually with a central semiconductor laser.

PubMed

Li, Ping; Wu, Jia-Gui; Wu, Zheng-Mao; Lin, Xiao-Dong; Deng, Dao; Liu, Yu-Ran; Xia, Guang-Qiong

2011-11-21

Based on a linear chain composed of a central semiconductor laser and two outer semiconductor lasers, chaos synchronization and bidirectional communication between two outer lasers have been investigated under the case that the central laser and the two outer lasers are coupled mutually, whereas there exists no coupling between the two outer lasers. The simulation results show that high-quality and stable isochronal synchronization between the two outer lasers can be achieved, while the cross-correlation coefficients between the two outer lasers and the central laser are very low under proper operation condition. Based on the high performance chaos synchronization between the two outer lasers, message bidirectional transmissions of bit rates up to 20 Gbit/s can be realized through adopting a novel decoding scheme which is different from that based on chaos pass filtering effect. Furthermore, the security of bidirectional communication is also analyzed. © 2011 Optical Society of America

Results of Kirari optical communication demonstration experiments with NICT optical ground station (KODEN) aiming for future classical and quantum communications in space

NASA Astrophysics Data System (ADS)

Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo

2012-05-01

Bi-directional ground-to-satellite laser communication experiments were successfully performed between the optical ground station developed by the National Institute of Information and Communications Technology (NICT), located in Koganei City in suburban Tokyo, and a low earth orbit (LEO) satellite, the "Kirari" Optical Inter-orbit Communications Engineering Test Satellite (OICETS). The experiments were conducted in cooperation with the Japan Aerospace Exploration Agency (JAXA), and called the Kirari Optical communication Demonstration Experiments with the NICT optical ground station (or KODEN). The ground-to-OICETS laser communication experiment was the first in-orbit demonstration involving the LEO satellite. The laser communication experiment was conducted since March 2006. The polarization characteristics of an artificial laser source in space, such as Stokes parameters, and the degree of polarization were measured through space-to-ground atmospheric transmission paths, which results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography on a global scale in the future. The Phase-5 experiment, international laser communications experiments were also successfully conducted with four optical ground stations located in the United States, Spain, Germany, and Japan from April 2009 to September 2009. The purpose of the Phase-5 experiment was to establish OICETS-to-ground laser communication links from the different optical ground stations and the statistical analyses such as the normalized power, scintillation index, probability density function, auto-covariance function, and power spectral density were performed. Thus the applicability of the satellite laser communications was demonstrated, aiming not only for geostationary earth orbit-LEO links but also for ground-to-LEO optical links. This paper presents the results of the KODEN experiments and mainly introduces the common analyses among the different optical ground stations.

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 multiplexer more than four goals or more, the ratio of received power and volume weight will be Obvious advantages, and can track multiple moving targets in flexible.It would to provide reference for the construction of earth integrated information networks.

Task one report: Optical system study. [characteristics of laser equipment for space communication systems

NASA Technical Reports Server (NTRS)

1973-01-01

An optical system which can be incorporated in a present day or near future space-borne laser communications system is described. Techniques of implementing these systems are presented and their design problems and use are discussed. Optical system weight is estimated as a function of aperture diameter for a typical present day or near future laser communication system. The optical communications system considered is a two-way, high data rate optical communications link from a spacecraft to a spacecraft or from a spacecraft to a ground station. Each station has a laser transmitter and receiver and a pointing and tracking system. Thus each station can track the laser transmitter of the other. Optical beamwidths are considered to be as small as an arc-second with the beam pointed to a fraction of this beamwidth.

The Lunar Laser Communication Demonstration: NASA's First Step Toward Very High Data Rate Support of Science and Exploration Missions

NASA Astrophysics Data System (ADS)

Boroson, Don M.; Robinson, Bryan S.

2014-12-01

Future NASA missions for both Science and Exploration will have needs for much higher data rates than are presently available, even with NASA's highly-capable Space- and Deep-Space Networks. As a first step towards this end, for one month in late 2013, NASA's Lunar Laser Communication Demonstration (LLCD) successfully demonstrated for the first time high-rate duplex laser communications between a satellite in lunar orbit, the Lunar Atmosphere and Dust Environment Explorer (LADEE), and multiple ground stations on the Earth. It constituted the longest-range laser communication link ever built and demonstrated the highest communication data rates ever achieved to or from the Moon.

Fast steering mirror for laser communication

NASA Astrophysics Data System (ADS)

Langenbach, Harald; Schmid, Manfred

2005-07-01

Future multimedia satellites require communication at large bandwidth which can be achieved by means of optical communication links. TESAT Spacecom is currently developing a Laser Communication Terminal (LCT) for such applications under DLR contract. EADS Astrium is developing and building the mechanisms for Pointing, Acquisition and Tracking (PAT) of the laser beam between two Laser Communication Terminals. Based on this development work the development of mechanism H/W to be flown on TerraSar X is currently under way. After a short description of the general arrangement of the Mechanisms inside the LCT, the paper describes the design of the fast steering mirrors (FSM) reflecting the critical requirements and the solutions how to achieve them.

Simultaneous trilateral communication based on three mutually coupled chaotic semiconductor lasers with optical feedback.

PubMed

Li, Qiliang; Lu, Shanshan; Bao, Qi; Chen, Dewang; Hu, Miao; Zeng, Ran; Yang, Guowei; Li, Shuqin

2018-01-10

In this paper, we propose a chaos-based scheme allowing for trilateral communication among three mutually coupled chaotic semiconductor lasers. The coupling through a partially transparent optical mirror between two lasers induces the chaotic dynamics. We numerically solve the delay rate equations of three lasers and demonstrate that the dynamics is completely synchronous. Herein, each laser is not only a transmitter but a receiver; three different messages are encoded by simultaneously modulating bias current of the three lasers. By monitoring the synchronization error between transmitter and receiver, and comparing the error with the message of the local laser, we can decipher the message of the sender. The investigation indicates that these messages introduced on the two ends of each link among three lasers can be simultaneously transmitted and restored, so the system can realize simultaneous trilateral communication. In this scheme, an eavesdropper can monitor the synchronization error, but one has no way to obtain the bits that are being sent, so the trilateral communication is secure.

III-V/II-VI Hybrid Quantum Well Mid-Infrared Lasers

DTIC Science & Technology

2005-01-25

semiconductor lasers are of great importance for many applications such as laser diode spectroscopy , pollution monitoring, low-loss optical communication...great importance for many applications such as laser diode spectroscopy, pollutant monitoring, low-losses longwavelength optical communication...InAsSb/CdMgSe laser structure 1.2. Characterization of the laser structures and interface quality (STM, EPFM etc) 1.3. Study of spontaneous and

Laser experiments in light cloudiness with the geostationary satellite ARTEMIS

NASA Astrophysics Data System (ADS)

Kuzkov, V.; Kuzkov, S.; Sodnik, Z.

2016-08-01

The geostationary satellite ARTEMIS was launched in July 2001. The satellite is equipped with a laser communication terminal, which was used for the world's first inter-satellite laser communication link between ARTEMIS and the low earth orbit satellite SPOT-4. Ground-to-space laser communication experiments were also conducted under various atmospheric conditions involving ESA's optical ground station. With a rapidly increasing volume of information transferred by geostationary satellites, there is a rising demand for high-speed data links between ground stations and satellites. For ground-to-space laser communications there are a number of important design parameters that need to be addressed, among them, the influence of atmospheric turbulence in different atmospheric conditions and link geometries. The Main Astronomical Observatory of NAS of Ukraine developed a precise computer tracking system for its 0.7 m AZT-2 telescope and a compact laser communication package LACES (Laser Atmosphere and Communication experiments with Satellites) for laser communication experiments with geostationary satellites. The specially developed software allows computerized tracking of the satellites using their orbital data. A number of laser experiments between MAO and ARTEMIS were conducted in partial cloudiness with some amount of laser light observed through clouds. Such conditions caused high break-up (splitting) of images from the laser beacon of ARTEMIS. One possible explanation is Raman scattering of photons on molecules of a water vapor in the atmosphere. Raman scattering causes a shift in a wavelength of the photons.In addition, a different value for the refraction index appears in the direction of the meridian for the wavelength-shifted photons. This is similar to the anomalous atmospheric refraction that appears at low angular altitudes above the horizon. We have also estimated the atmospheric attenuation and the influence of atmospheric turbulence on observed results. The results and interpretations are presented in the paper.

Study of opto-acoustic communication between air and underwater carrier

NASA Astrophysics Data System (ADS)

Zong, Si-Guang; Liu, Tao; Cao, Jing; He, Qi-Yi

2018-02-01

How to solve the communication problem to the underwater target has turned into one of the subjects that the militarists of all over the world commonly concern. Laser-induced acoustic signal is a new approach for underwater acoustic source, which has much virtue such as high intensity, short pulse and broad frequency. The paper studies the opto-acoustic communication method. The acoustic signal characteristic of laser-induced breakdown is studied and corresponding theory model is systemically analyzed. The opto-acoustic communication experimental measure investigation is formed with the high power laser, water tank and high frequency hydrophone. The characteristic of acoustic signal is analyzed, such as intensity and frequency. This makes a stride for pursing the feasibility of laser-acoustic underwater communication.

Semiconductor lasers for versatile applications from global communications to on-chip interconnects

NASA Astrophysics Data System (ADS)

Arai, Shigehisa

2015-01-01

Since semiconductor lasers were realized in 1962, various efforts have been made to enrich human life thorough novel equipments and services. Among them optical fiber communications in global communications have brought out marvelous information technology age represented by the internet. In this paper, emerging topics made on GaInAsP/InP based long-wavelength lasers toward ultra-low power consumption semiconductor lasers for optical interconnects in supercomputers as well as in future LSIs are presented.

Study and design on USB wireless laser communication system

NASA Astrophysics Data System (ADS)

Wang, Aihua; Zheng, Jiansheng; Ai, Yong

2004-04-01

We give the definition of USB wireless laser communication system (WLCS) and the brief introduction to the protocol of USB, the standard of hardware is also given. The paper analyses the hardware and software of USB WLCS. Wireless laser communication part and USB interface circuit part are discussed in detail. We also give the periphery design of the chip AN2131Q, the control circuit to realize the transformation from parallel port to serial bus, and the circuit of laser sending and receiving of laser communication part, which are simply, cheap and workable. And then the four part of software are analyzed as followed. We have consummated the ISR in the firmware frame to develop the periphery device of USB. We have debugged and consummated the 'ezload,' and the GPD of the drivers. Windows application performs functions and schedules the corresponding API functions to let the interface practical and beautiful. The system can realize USB wireless laser communication between computers, which distance is farther than 50 meters, and top speed can be bigger than 8 Mbps. The system is of great practical sense to resolve the issues of high-speed communication among increasing districts without fiber trunk network.

Laser Communication--An Ideal Student Project.

ERIC Educational Resources Information Center

Leung, W. P.; And Others

1980-01-01

Describes a project on the application of the laser which aims to stimulate the interest of undergraduate students in applied physics and to demonstrate the interaction between light and ultrasonic waves by building a simple laser communication system. (SK)

External Cavity Coherent Transmitter Modules

DTIC Science & Technology

1990-11-01

Lasers 141 Tunability Aspects of DFB External Cavity Semiconductor Lasers Harish R. D. Sunak & Clark P. Engert Fiber Optical Communications Laboratory...Linewidth Considerations for DFB External Cavity Semiconductor Lasers Harish R. D. Sunak & Clark P. Engert Fiber Optical Communications Laboratory

Temporal characteristic analysis of laser-modulated pulsed X-ray source for space X-ray communication

NASA Astrophysics Data System (ADS)

Hang, Shuang; Liu, Yunpeng; Li, Huan; Tang, Xiaobin; Chen, Da

2018-04-01

X-ray communication (XCOM) is a new communication type and is expected to realize high-speed data transmission in some special communication scenarios, such as deep space communication and blackout communication. This study proposes a high-speed modulated X-ray source scheme based on the laser-to-X-ray conversion. The temporal characteristics of the essential components of the proposed laser-modulated pulsed X-ray source (LMPXS) were analyzed to evaluate its pulse emission performance. Results show that the LMPXS can provide a maximum modulation rate up to 100 Mbps which is expected to significantly improve the data rate of XCOM.

Cavity-Dumped Communication Laser Design

NASA Technical Reports Server (NTRS)

Roberts, W. T.

2003-01-01

Cavity-dumped lasers have significant advantages over more conventional Q-switched lasers for high-rate operation with pulse position modulation communications, including the ability to emit laser pulses at 1- to 10-megahertz rates, with pulse widths of 0.5 to 5 nanoseconds. A major advantage of cavity dumping is the potential to vary the cavity output percentage from pulse to pulse, maintaining the remainder of the energy in reserve for the next pulse. This article presents the results of a simplified cavity-dumped laser model, establishing the requirements for cavity efficiency and projecting the ultimate laser efficiency attainable in normal operation. In addition, a method of reducing or eliminating laser dead time is suggested that could significantly enhance communication capacity. The design of a laboratory demonstration laser is presented with estimates of required cavity efficiency and demonstration potential.

Reflector control technology in space laser communication

NASA Astrophysics Data System (ADS)

Xie, Meilin; Ma, Caiwen; Yao, Cheng; Huang, Wei; Lian, Xuezheng; Feng, Xubin; Jing, Feng

2017-11-01

The optical frequencies band is used as information carrier to realize laser communication between two low-orbit micro-satellites in space which equipped with inter-satellite laser communication terminals, optical switches, space routers and other payload. The laser communication terminal adopts a two-dimensional turntable with a single mirror structure. In this paper, the perturbation model of satellite platform is established in this paper. The relationship between the coupling and coordinate transformation of satellite disturbance is analyzed and the laser pointing vector is deduced. Using the tracking differentiator to speed up the circular grating angle information constitute speed loop feedback, which avoids the problem of error amplification caused by the high frequency of the conventional difference algorithm. Finally, the suppression ability of the satellite platform disturbance and the tracking accuracy of the tracking system are simulated and analyzed. The results show that the tracking accuracy of the whole system is 10μrad in the case of satellite vibration, which provides the basis for the optimization of the performance of the space-borne laser communication control system.

Thermal tuning On narrow linewidth fiber laser

NASA Astrophysics Data System (ADS)

Han, Peiqi; Liu, Tianshan; Gao, Xincun; Ren, Shiwei

2010-10-01

At present, people have been dedicated to high-speed and large-capacity optical fiber communication system. Studies have been shown that optical wavelength division multiplexing (WDM) technology is an effective means of communication to increase the channel capacity. Tunable lasers have very important applications in high-speed, largecapacity optical communications, and distributed sensing, it can provide narrow linewidth and tunable laser for highspeed optical communication. As the erbium-doped fiber amplifier has a large gain bandwidth, the erbium-doped fiber laser can be achieved lasing wavelength tunable by adding a tunable filter components, so tunable filter device is the key components in tunable fiber laser.At present, fiber laser wavelength is tuned by PZT, if thermal wavelength tuning is combined with PZT, a broader range of wavelength tuning is appearance . Erbium-doped fiber laser is used in the experiments,the main research is the physical characteristics of fiber grating temperature-dependent relationship and the fiber grating laser wavelength effects. It is found that the fiber laser wavelength changes continuously with temperature, tracking several temperature points observed the self-heterodyne spectrum and found that the changes in spectra of the 3dB bandwidth of less than 1kHz, and therefore the fiber laser with election-mode fiber Bragg grating shows excellent spectral properties and wavelength stability.

Electronic Subsystems For Laser Communication System

NASA Technical Reports Server (NTRS)

Long, Catherine; Maruschak, John; Patschke, Robert; Powers, Michael

1992-01-01

Electronic subsystems of free-space laser communication system carry digital signals at 650 Mb/s over long distances. Applicable to general optical communications involving transfer of great quantities of data, and transmission and reception of video images of high definition.

Injection chaining of diode-pumped single-frequency ring lasers for free-space communication

NASA Technical Reports Server (NTRS)

Cheng, E. A. P.; Kane, T. J.; Wallace, R. W.; Cornwell, D. M., Jr.

1991-01-01

A high-power three-stage laser suitable for use in a space communication system has been built. This laser uses three diode-pumped Nd:YAG oscillators coherently combined using the technique of injection chaining. All three oscillators are in one compact and permanently aligned package, and are actively frequency locked to provide CW single frequency output. The three stages provide the redundancy desirable for space communications.

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.

High-Speed Operation of Interband Cascade Lasers

NASA Technical Reports Server (NTRS)

Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Wright, Malcom W.; Farr, William H.; Yang, Rui Q.; Liu, H. C.

2010-01-01

Optical sources operating in the atmospheric window of 3-5 microns are of particular interest for the development of free-space optical communication link. It is more advantageous to operate the free-space optical communication link in 3-5-microns atmospheric transmission window than at the telecom wavelength of 1.5 m due to lower optical scattering, scintillation, and background radiation. However, the realization of optical communications at the longer wavelength has encountered significant difficulties due to lack of adequate optical sources and detectors operating in the desirable wavelength regions. Interband Cascade (IC) lasers are novel semiconductor lasers that have a great potential for the realization of high-power, room-temperature optical sources in the 3-5-microns wavelength region, yet no experimental work, until this one, was done on high-speed direct modulation of IC lasers. Here, highspeed interband cascade laser, operating at wavelength 3.0 m, has been developed and the first direct measurement of the laser modulation bandwidth has been performed using a unique, highspeed quantum well infrared photodetector (QWIP). The developed laser has modulation bandwidth exceeding 3 GHz. This constitutes a significant increase of the IC laser modulation bandwidth over currently existing devices. This result has demonstrated suitability of IC lasers as a mid-IR light source for multi-GHz free-space optical communications links

The integration of laser communication and ranging

NASA Astrophysics Data System (ADS)

Xu, Mengmeng; Sun, Jianfeng; Zhou, Yu; Zhang, Bo; Zhang, Guo; Li, Guangyuan; He, Hongyu; Lao, Chenzhe

2017-08-01

The method to realize the integration of laser communication and ranging is proposed in this paper. In the transmitter of two places, the ranging codes with uniqueness, good autocorrelation and cross-correlation properties are embed in the communication data and the encoded with the communication data to realize serial communication. And then the encoded data are modulated and send to each other, which can realize high speed two one-way laser communication. At the receiver, we can get the received ranging code after the demodulation, decoding and clock recovery. The received ranging codes and the local ranging codes do the autocorrelation to get a roughly range, while the phase difference between the local clock and the recovery clock to achieve the precision of the distance.

Some Specific Speculations For Future Applications Of Lasers In Medicine And Surgery

NASA Astrophysics Data System (ADS)

Goldman, Leon

1982-12-01

With the increasing market in laser medicine and surgery it is well to plan ahead so that there will be increasing production. For the concept of so-called laser biostimulation with various low output laser systems there is much need for well controlled studies to avoid discrediting all of laser medicine. There is great potential for the future in laser instrumentation for heart disease, cancer research, diagnoses and treatment, all fields of surgery, and in perinatology. Also, laser communications and information handling can make for deliverance of better health care. It is well to open up better lines of communication between laser industry and modern medicine.

Compact optical duplicate system for satellite-ground laser communications: application of averaging effects

NASA Astrophysics Data System (ADS)

Nakayama, Tomoko; Takayama, Yoshihisa; Fujikawa, Chiemi; Watanabe, Eriko; Kodate, Kashiko

2014-09-01

In recent years, there has been considerable interest in satellite-ground laser communication due to an increase in the quantity of data exchanged between satellites and the ground. However, improving the quality of this data communication is necessary as laser communication is vulnerable to air fluctuation. We first verify the spatial and temporal averaging effects using light beam intensity images acquired from middle-range transmission experiments between two ground positions and the superposition of these images using simulations. Based on these results, we propose a compact and lightweight optical duplicate system as a multi-beam generation device with which it is easy to apply the spatial averaging effect. Although an optical duplicate system is already used for optical correlation operations, we present optimum design solutions, design a compact optical duplicate system for satellite-ground laser communications, and demonstrate the efficacy of this system using simulations.

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.…

Wideband 1.064 micrometer detector evaluation

NASA Technical Reports Server (NTRS)

Green, S. I.

1975-01-01

The performance of several candidate detectors for use as communications detectors in a 400 Mbps 1.064 micrometers laser communication system was evaluated. The results of communication system Bit Error Rate (BER) testing for the best detector of each type are summarized. Complete testing data of each type detector is presented. The 400 Mbps 1.064 micrometers communication system receiver test bed is described. The best communication system results for each detector type are included. Performance comparisons are made at 0.000001 BER, the specification level chosen for satellite laser communication links. The data is presented in two groups. The first indicates the best performance levels that can be expected on normal space laser communication system operation. The second cites the best performance levels which can be achieved by focusing the signal to diffraction limited spots on the photosensitive area.

Solid-state lasers for coherent communication and remote sensing

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1990-01-01

Laser development, high efficiency, high power second harmonic generation, operation of optical parametric oscillators for wavelength diversity and tunability, and studies in coherent communications are reviewed.

New trends in laser satellite communications: design and limitations

NASA Astrophysics Data System (ADS)

Císar, J.; Wilfert, O.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Arce-Diego, J. L.

2008-11-01

Optical communications offer a capable alternative to radio frequency (RF) communications for applications where high data-rate is required. This technology is particularly promising and challenging in the field of future inter-satellite communications. The term laser satellite communications (LSC) stands for optical links between satellites and/or high altitude platforms (HAPs). However, optical links between an earth station and a satellite or HAPs can be also involved. This work gives an overview of nowadays laser satellite communications. Particularly, it is focused on the factors causing degradation of the optical beam in the atmosphere. If an optical link passes through the atmosphere, it suffers from various influences such as attenuation due to absorption and scattering, intensity fluctuations due to atmospheric turbulence and background radiation. Furthermore, platform vibrations cause mispointing and following tracking losses. Suitable devices and used pointing and tracking system for laser satellite communications are discussed. At the end, various scenarios of the optical links and calculations of their power link budgets and limitations are designed. Implemented software is used for calculation of optical links. This work proves that the Free Space Optics (FSO) systems on mobile platforms, like satellites and HAPs are a promising solution for future communication networks.

NASA's Optical Communications Program for 2015 and Beyond

NASA Technical Reports Server (NTRS)

Cornwell, Donald M.

2015-01-01

NASA's Space Communications and Navigation (SCaN) program at NASA headquarters is pursuing a vibrant and wide-ranging optical communications program for further planetary and near-Earth missions following the spectacular success of NASA's Lunar Laser Communication Demonstration (LLCD) from the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft orbiting the moon in 2013. This invited paper will discuss NASA's new laser communication missions, key scenarios and details, and the plans to infuse this new technology into NASA's existing communications networks.

Optical communication in free space

NASA Technical Reports Server (NTRS)

Plotkin, H. H.; Mcavoy, N.; Fitzmaurice, M. W.

1974-01-01

Two classes of laser communication systems for handling very high data rates across inter-satellite distances are considered that provide for high antenna gains, wide modulation bandwidths, and optical receiver sensitivities. System design considerations are based upon the carbon dioxide laser modulation to accommodate digital or analog information, and the neodymium doped YAG laser pulse for digital modulation.

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.

Single-frequency diode-pumped lasers for free-space optical communication

NASA Technical Reports Server (NTRS)

Kane, Thomas J.; Cheng, Emily A. P.; Gerstenberger, David C.; Wallace, Richard W.

1990-01-01

Recent advances in laser technology for intersatellite optical communication systems are reviewed and illustrated with graphs and diagrams. Topics addressed include (1) single-frequency diode-pumped Nd:YAG lasers of monolithic ring configuration (yielding 368-384 mW output power with 1-W pumping), (2) injection chaining of up to 10 monolithic resonators to achieve redundancy and/or higher output power, (3) 2-kHz-linewidth 5-mW versions of (1) which are tunable over a 30-MHz range for use as local oscillators in coherent communication, (4) resonant external modulation and doubling or resonant phase modulation of diode-pumped lasers, and (5) wavelength multiplexing.

In-orbit verification of small optical transponder (SOTA): evaluation of satellite-to-ground laser communication links

NASA Astrophysics Data System (ADS)

Takenaka, Hideki; Koyama, Yoshisada; Akioka, Maki; Kolev, Dimitar; Iwakiri, Naohiko; Kunimori, Hiroo; Carrasco-Casado, Alberto; Munemasa, Yasushi; Okamoto, Eiji; Toyoshima, Morio

2016-03-01

Research and development of space optical communications is conducted in the National Institute of Information and Communications Technology (NICT). The NICT developed the Small Optical TrAnsponder (SOTA), which was embarked on a 50kg-class satellite and launched into a low earth orbit (LEO). The space-to-ground laser communication experiments have been conducted with the SOTA. Atmospheric turbulence causes signal fadings and becomes an issue to be solved in satellite-to-ground laser communication links. Therefore, as error-correcting functions, a Reed-Solomon (RS) code and a Low-Density Generator Matrix (LDGM) code are implemented in the communication system onboard the SOTA. In this paper, we present the in-orbit verification results of SOTA including the characteristic of the functions, the communication performance with the LDGM code via satellite-to-ground atmospheric paths, and the link budget analysis and the comparison between theoretical and experimental results.

High speed visible light communication using blue GaN laser diodes

NASA Astrophysics Data System (ADS)

Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

2016-10-01

GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

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.

Site survey for optimum location of Optical Communication Experimental Facility

NASA Technical Reports Server (NTRS)

1968-01-01

Site survey was made to determine the optimum location for an Optical Communication Experimental Facility /OCEF/ and to recommend several sites, graded according to preference. A site was desired which could perform two-way laser communication with a spacecraft and laser tracking with a minimum of interruption by weather effects.

Theoretical analysis and experimental study of constraint boundary conditions for acquiring the beacon in satellite-ground laser communications

NASA Astrophysics Data System (ADS)

Yu, Siyuan; Wu, Feng; Wang, Qiang; Tan, Liying; Ma, Jing

2017-11-01

Acquisition and recognition for the beacon is the core technology of establishing the satellite optical link. In order to acquire the beacon correctly, the beacon image should be recognized firstly, excluding the influence of the background light. In this processing, many factors will influence the recognition precision of the beacon. This paper studies the constraint boundary conditions for acquiring the beacon from the perspective of theory and experiment, and as satellite-ground laser communications, an approach for obtaining the adaptive segmentation method is also proposed. Finally, the long distance laser communication experiment (11.16 km) verifies the validity of this method and the tracking error with the method is the least compared with the traditional approaches. The method helps to greatly improve the tracking precision in the satellite-ground laser communications.

Bibliography of Soviet Laser Developments, Number 44 November - December 1979.

DTIC Science & Technology

1980-08-13

Laser Materials, Ultrashort Pulse Generation, X-ray Lasers , Gamma Lasers , Laser Theory, Laser Biological Effects, Laser Communications, Laser Beam... lasers ; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers ; and...and V.P. Feshchenko (51). Stimulated Raman scattering in absorbing media during pumping by ultrashort laser

Bibliography of Soviet Laser Developments, No. 18, October - December 1974

DTIC Science & Technology

1975-04-25

IIV Lasers, Laser Theory , Laser Biological Effects, Laser Communications, Laser Computer Technology, Holography, Laser Chemical Effects...spectros.copy of laser materials; ultrashort pulse generation; crystal growing; theoretical aspects of advanced lasers; and general laser theory Laser...Semiconductor: Mixed Junction 5 6. Semiconductor: Heterojunction ^ 7. Semiconductor: Theory 8. Nd:Glass B. Liquid Lasers 1

Free Space Laser Communication Experiments from Earth to the Lunar Reconnaissance Orbiter in Lunar Orbit

NASA Technical Reports Server (NTRS)

Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Zellar, Ronald S.; Fong, Wai H; Krainak, Michael A.; Neumann, Gregory A.; Smith, David E.

2013-01-01

Laser communication and ranging experiments were successfully conducted from the satellite laser ranging (SLR) station at NASA Goddard Space Flight Center (GSFC) to the Lunar Reconnaissance Orbiter (LRO) in lunar orbit. The experiments used 4096-ary pulse position modulation (PPM) for the laser pulses during one-way LRO Laser Ranging (LR) operations. Reed-Solomon forward error correction codes were used to correct the PPM symbol errors due to atmosphere turbulence and pointing jitter. The signal fading was measured and the results were compared to the model.

Transmitters and receivers in free space optical communications for Deep Space links

NASA Technical Reports Server (NTRS)

Beebe, J.

2003-01-01

Two of the many research areas integral making a Mars-Earth optical communication link a reality are optical antenna design and laser transmitter design. This paper addresses areas of both of these by exploring a mode-matched design for a cavity-dumped communications laser, and by reporting on the initial stages of the analysis of an existing 100 inch telescope for use as an optical communications receiver.

Transceiver for Space Station Freedom

NASA Technical Reports Server (NTRS)

Fitzmaurice, M.; Bruno, R.

1990-01-01

This paper describes the design of the Laser Communication Transceiver (LCT) system which was planned to be flight tested as an attached payload on Space Station Freedom. The objective in building and flight-testing the LCT is to perform a broad class of tests addressing the critical aspects of space-based optical communications systems, providing a base of experience for applying laser communications technology toward future communications needs. The LCT's functional and performance requirements and capabilities with respect to acquisition, spatial tracking and pointing, communications, and attitude determination are discussed.

Transceiver for Space Station Freedom

NASA Astrophysics Data System (ADS)

Fitzmaurice, M.; Bruno, R.

1990-07-01

This paper describes the design of the Laser Communication Transceiver (LCT) system which was planned to be flight tested as an attached payload on Space Station Freedom. The objective in building and flight-testing the LCT is to perform a broad class of tests addressing the critical aspects of space-based optical communications systems, providing a base of experience for applying laser communications technology toward future communications needs. The LCT's functional and performance requirements and capabilities with respect to acquisition, spatial tracking and pointing, communications, and attitude determination are discussed.

The OICETS mission

NASA Astrophysics Data System (ADS)

Jono, Takashi; Arai, Katsuyoshi

2017-11-01

The Optical Inter-orbit Communications Engineering Test Satellite (OICETS) was successfully launched on 23th August 2005 and thrown into a circular orbit at the altitude of 610 km. The main mission is to demonstrate the free-space inter satellite laser communications with the cooperation of the Advanced Relay and Technology Mission (ARTEMIS) geostationary satellite developed by the European Space Agency. This paper presents the overview of the OICETS and laser terminal, a history of international cooperation between Japan Aerospace Exploration Agency (JAXA) and ESA and typical results of the inter-orbit laser communication experiment carried out with ARTEMIS.

AlGaInN laser diode technology for GHz high-speed visible light communication through plastic optical fiber and water

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Malcolm A.; White, Henry; Watson, Scott; Kelly, Antony E.

2016-02-01

AlGaInN ridge waveguide laser diodes are fabricated to achieve single-mode operation with optical powers up to 100 mW at ˜420 nm for visible free-space, underwater, and plastic optical fiber communication. We report high-frequency operation of AlGaInN laser diodes with data transmission up to 2.5 GHz for free-space and underwater communication and up to 1.38 GHz through 10 m of plastic optical fiber.

Development and Characterization of a Small Spacecraft Electro-Optic Scanner for Free-Space Laser Communications

NASA Technical Reports Server (NTRS)

Davis, Scott; Lichter, Michael; Raible, Daniel

2016-01-01

Emergent data-intensive missions coupled with dramatic reductions in spacecraft size plus an increasing number of space-based missions necessitates new high performance, compact and low cost communications technology. Free space optical communications offer advantages including orders of magnitude increase for data rate performance, increased security, immunity to jamming and lack of frequency allocation requirements when compared with conventional radio frequency (RF) means. The spatial coherence and low divergence associated with the optical frequencies of laser communications lends themselves to superior performance, but this increased directionality also creates one of the primary technical challenges in establishing a laser communications link by repeatedly and reliably pointing the beam onto the receive aperture. Several solutions have emerged from wide angle (slow) mechanical articulation systems, fine (fast) steering mirrors and rotating prisms, inertial compensation gyros and vibration isolation cancellation systems, but each requires moving components and imparts a measured amount of burden on the host platform. The complexity, cost and size of current mechanically scanned solutions limits their platform applicability, and restricts the feasibility of deploying optical communications payloads on very compact spacecraft employing critical systems. A high speed, wide angle, non-mechanical solution is therefore desirable. The purpose of this work is to share the development, testing, and demonstration of a breadboard prototype electro-optic (EO) scanned laser-communication link (see Figure 1). This demonstration is a step toward realizing ultra-low Size, Weight and Power (SWaP) SmallSat/MicroSat EO non-mechanical laser beam steering modules for high bandwidth ( greater than Gbps) free-space data links operating in the 1550 nm wavelength bands. The elimination of all moving parts will dramatically reduce SWaP and cost, increase component lifetime and reliability, and simplify the system design of laser communication modules. This paper describes the target mission architectures and requirements (few cubic centimeters of volume, 10's of grams of weight with milliwatts of power) and design of the beam steering module. Laboratory metrology is used to determine the component performance including horizontal and vertical resolution (20urad) as a function of control voltage (see Figure 2), transition time (0.1-1ms), pointing repeatability and optic insertion loss. A test bed system demonstration, including a full laser communications link, is conducted. The capabilities of this new EO beam steerer provide an opportunity to dramatically improve space communications through increased utilization of laser technology on smaller platforms than were previously attainable.

Bibliography of Soviet Laser Developments. Number 43, September-October 1979.

DTIC Science & Technology

1980-06-01

Laser Materials, Ultrashort Pulse Generation, X-ray Lasers , Gamma Lasers , Laser Theory, Laser Biological Effects, Laser Communications, Laser ...chemical lasers ; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; theoretical aspects of advanced lasers ; and...and A.L. Traynin (0). Study on single crystals of shaped germanium, irradiated by a pulsed CO 2 laser .

High frequency optical communications; Proceedings of the Meeting, Cambridge, MA, Sept. 23, 24, 1986

NASA Astrophysics Data System (ADS)

Ramer, O. Glenn; Sierak, Paul

Topics discussed in this volume include systems and applications, detectors, sources, and coherent communications. Papers are presented on RF fiber optic links for avionics applications, fiber optics and optoelectronics for radar and electronic warfare applications, symmetric coplanar electrodes for high-speed Ti:LiNbO3 devices, and surface wave electrooptic modulator. Attention is given to X-band RF fiber-optic links, fiber-optic links for microwave signal transmission, GaAs monolithic receiver and laser driver for GHz transmission rates, and monolithically integrable high-speed photodetectors. Additional papers are on irregular and chaotic behavior of semiconductor lasers under modulation, high-frequency laser package for microwave optical communications, receiver modeling for coherent light wave communications, and polarization sensors and controllers for coherent optical communication systems.

Free-space and underwater GHz data transmission using AlGaInN laser diode technology

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.

2016-05-01

Laser diodes fabricated from the AlGaInN material system is an emerging technology for defence and security applications; in particular for free space laser communication. Conventional underwater communication is done acoustically with very slow data rates, short reach, and vulnurable for interception. AlGaInN blue-green laser diode technology allows the possibility of both airbourne links and underwater telecom that operate at very fast data rates (GHz), long reach (100's of metres underwater) and can also be quantum encrypted. The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with optical powers of <100mW. Visible light communications at high frequency (up to 2.5 Gbit/s) using a directly modulated 422nm Galliumnitride (GaN) blue laser diode is reported in free-space and underwater.

Bibliography of Soviet Laser Developments, Number 85, September - October 1986.

DTIC Science & Technology

1987-11-01

Ultrashort Pulse Generation, Laser Crystal Growing, Free Electron Lasers , Laser Theory, Laser Biological Effects, Laser Communications, Laser ...liquid, gas, and chemical lasers ; components; nonlinear optics; spectroscopy of laser materials; ultrashort pulse generation; crystal growing; theoretical...30 5. Self-focusing 30 6. Acoustic Interaction ................ 30 G. Spectroscopy of Laser Materials ......... 33 H. Ultrashort

Highly Efficient Nd:yag Lasers for Free-space Optical Communications

NASA Technical Reports Server (NTRS)

Sipes, D. L., Jr.

1985-01-01

A highly efficient Nd:YAG laser end-pumped by semiconductor lasers as a possible free-space optical communications source is discussed. Because this concept affords high pumping densities, a long absorption length, and excellent mode-matching characteristics, it is estimated that electrical-to-optical efficiencies greater than 5% could be achieved. Several engineering aspects such as resonator size and configuration, pump collecting optics, and thermal effects are also discussed. Finally, possible methods for combining laser-diode pumps to achieve higher output powers are illustrated.

Acousto-optic pointing and tracking systems for free-space laser communications

NASA Astrophysics Data System (ADS)

Nikulin, V.; Khandekar, R.; Sofka, J.; Tartakovsky, G.

2005-08-01

Implementation of long-range laser communication systems holds great promise for high-bandwidth applications. They are viewed as a technology that in the nearest future will handle most of the "last mile" communication traffic for the individual subscribers, corporate offices, military, and possibly deep space probes. Indeed, lasers allow for concentration of energy within tightly focused beams and narrow spectral interval, thus offering high throughput, information security, weight and size of components and power requirements that could not be matched by RF systems. However, the advantages of optical communication systems come in the same package with several major challenges. In particular, high data rates should be complemented by high-precision wide-bandwidth position control of a laser beam. In many applications the ability to maintain a link is affected by the complex maneuvers performed by mobile communication platforms, resident vibrations, and atmospheric effects. The search for the most effective and reliable way to shape and steer the laser beam is an on-going effort. This paper is focused on the application of acousto-optic technology as an alternative to electro-mechanical devices. With realization that an acousto-optic Bragg cell is only a component of the entire communication system, which should perform complex tasks of acquisition, pointing, and tracking of the remote terminal, we present an attempt to consider this problem from the "systems" point of view.

Accurate beacon positioning method for satellite-to-ground optical communication.

PubMed

Wang, Qiang; Tong, Ling; Yu, Siyuan; Tan, Liying; Ma, Jing

2017-12-11

In satellite laser communication systems, accurate positioning of the beacon is essential for establishing a steady laser communication link. For satellite-to-ground optical communication, the main influencing factors on the acquisition of the beacon are background noise and atmospheric turbulence. In this paper, we consider the influence of background noise and atmospheric turbulence on the beacon in satellite-to-ground optical communication, and propose a new locating algorithm for the beacon, which takes the correlation coefficient obtained by curve fitting for image data as weights. By performing a long distance laser communication experiment (11.16 km), we verified the feasibility of this method. Both simulation and experiment showed that the new algorithm can accurately obtain the position of the centroid of beacon. Furthermore, for the distortion of the light spot through atmospheric turbulence, the locating accuracy of the new algorithm was 50% higher than that of the conventional gray centroid algorithm. This new approach will be beneficial for the design of satellite-to ground optical communication systems.

NASA's current activities in free space optical communications

NASA Astrophysics Data System (ADS)

Edwards, Bernard L.

2017-11-01

NASA and other space agencies around the world are currently developing free space optical communication systems for both space-to-ground links and space-to-space links. This paper provides an overview of NASA's current activities in free space optical communications with a focus on Near Earth applications. Activities to be discussed include the Lunar Laser Communication Demonstration, the Laser Communications Relay Demonstration, and the commercialization of the underlying technology. The paper will also briefly discuss ongoing efforts and studies for Deep Space optical communications. Finally the paper will discuss the development of international optical communication standards within the Consultative Committee for Space Data Systems.

High-Rate Laser Communications for Human Exploration and Science

NASA Astrophysics Data System (ADS)

Robinson, B. S.; Shih, T.; Khatri, F. I.; King, T.; Seas, A.

2018-02-01

Laser communication links has been successfully demonstrated on recent near-Earth and lunar missions. We present a status of this development work and its relevance to a future Deep Space Gateway supporting human exploration and science activities.

Solid state laser communications in space (SOLACOS) position, acquisition, and tracking (PAT) subsystem implementation

NASA Astrophysics Data System (ADS)

Flemmig, Joerg; Pribil, Klaus

1994-09-01

This paper presents the concept and implementation aspects of the Pointing, Acquisition and Tracking Subsystem (PAT) which is developed in the frame of the SOLACOS (Solid State Laser Communications in Space) program.

NASA's First Laser Communication System

NASA Image and Video Library

2017-12-08

A new NASA-developed, laser-based space communication system will enable higher rates of satellite communications similar in capability to high-speed fiber optic networks on Earth. The space terminal for the Lunar Laser Communication Demonstration (LLCD), NASA's first high-data-rate laser communication system, was recently integrated onto the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft. LLCD will demonstrate laser communications from lunar orbit to Earth at six times the rate of the best modern-day advanced radio communication systems. Credit: NASA ----- What is LADEE? The Lunar Atmosphere and Dust Environment Explorer (LADEE) is designed to study the Moon's thin exosphere and the lunar dust environment. An "exosphere" is an atmosphere that is so thin and tenuous that molecules don't collide with each other. Studying the Moon's exosphere will help scientists understand other planetary bodies with exospheres too, like Mercury and some of Jupiter's bigger moons. The orbiter will determine the density, composition and temporal and spatial variability of the Moon's exosphere to help us understand where the species in the exosphere come from and the role of the solar wind, lunar surface and interior, and meteoric infall as sources. The mission will also examine the density and temporal and spatial variability of dust particles that may get lofted into the atmosphere. The mission also will test several new technologies, including a modular spacecraft bus that may reduce the cost of future deep space missions and demonstrate two-way high rate laser communication for the first time from the Moon. LADEE now is ready to launch when the window opens on Sept. 6, 2013. Read more: www.nasa.gov/ladee NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Semiconductor optoelectronic devices for free-space optical communications

NASA Technical Reports Server (NTRS)

Katz, J.

1983-01-01

The properties of individual injection lasers are reviewed, and devices of greater complexity are described. These either include or are relevant to monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. The potential of AlGaAs laser technology for free-space optical communications systems is demonstrated. These solid-state components, which can generate and modulate light, combine the power of a number of sources and perform at least part of the beam pointing functions. Methods are proposed for overcoming the main drawback of semiconductor lasers, that is, their inability to emit the needed amount of optical power in a single-mode operation.

The development of a low-cost laser communication system for the classroom

NASA Astrophysics Data System (ADS)

Sparks, Robert T.; Pompea, Stephen M.; Walker, Constance E.

2007-06-01

Hands-On Optics (HOO) is a National Science Foundation funded program to bring optics education to underserved middle school students. We have developed the culminating module (Module 6) on laser communication. Students learn how lasers can be modulated to carry information. The main activity of this module is the construction of a low-cost laser communication system. The system can be built using parts readily available at a local electronics store for approximately US $60. The system can be used to transmit a person's voice or music from sources such as an mp3 player or radio over a distance of 350 feet. We will provide detailed plans on how to build the system in this paper.

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.

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.

The Laser Communications Relay Demonstration Experiment Program

NASA Technical Reports Server (NTRS)

Israel, Dave

2017-01-01

This paper elaborates on the Laser Communications Relay Demonstration (LCRD) Experiment Program, which will engage in a number of pre-determined experiments and also call upon a wide variety of experimenters to test new laser communications technology and techniques, and to gather valuable data. LCRD is a joint project between NASAs Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will test the functionality in various settings and scenarios of optical communications links from a GEO payload to ground stations in Southern California and Hawaii over a two-year period following launch in 2019. The LCRD investigator team will execute numerous experiments to test critical aspects of laser communications activities over real links and systems, collecting data on the effects of atmospheric turbulence and weather on performance and communications availability. LCRD will also incorporate emulations of target scenarios, including direct-to-Earth (DTE) links from user spacecraft and optical relay providers supporting user spacecraft. To supplement and expand upon the results of these experiments, the project also includes a Guest Experimenters Program, which encourages individuals and groups from government agencies, academia and industry to propose diverse experiment ideas.

The Laser Communications Relay Demonstration Experiment Program

NASA Technical Reports Server (NTRS)

Israel, David J.; Edwards, Bernard L.; Moores, John D.; Piazzolla, Sabino; Merritt, Scott

2017-01-01

This paper elaborates on the Laser Communications Relay Demonstration (LCRD) Experiment Program, which will engage in a number of pre-determined experiments and also call upon a wide variety of experimenters to test new laser communications technology and techniques, and to gather valuable data. LCRD is a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will test the functionality in various settings and scenarios of optical communications links from a GEO (Geosynchronous Earth Orbit) payload to ground stations in Southern California and Hawaii over a two-year period following launch in 2019. The LCRD investigator team will execute numerous experiments to test critical aspects of laser communications activities over real links and systems, collecting data on the effects of atmospheric turbulence and weather on performance and communications availability. LCRD will also incorporate emulations of target scenarios, including direct-to-Earth (DTE) links from user spacecraft and optical relay providers supporting user spacecraft. To supplement and expand upon the results of these experiments, the project also includes a Guest Experimenters Program, which encourages individuals and groups from government agencies, academia and industry to propose diverse experiment ideas.

Wideband 1.064 micrometer detector evaluation. [for application to space laser communication systems

NASA Technical Reports Server (NTRS)

Green, S. I.

1977-01-01

Several types of communications detectors for use in a 400 Mbps 1.064 micrometer laser communication system were evaluated and characterized. The communication system Bit Error Rate (BER) performance was measured, and test results for the best detector of each type are summarized. The complete BER curves are presented. The 400 Mbps 1.064 micrometer communication system receiver test bed is described. The best performance levels which can be achieved by focusing the signal to diffraction limited spots on the photosensitive area are cited.

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.

Solid-state lasers for coherent communication and remote sensing

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1992-01-01

Semiconductor-diode laser-pumped solid-state lasers have properties that are superior to other lasers for the applications of coherent communication and remote sensing. These properties include efficiency, reliability, stability, and capability to be scaled to higher powers. We have demonstrated that an optical phase-locked loop can be used to lock the frequency of two diode-pumped 1.06 micron Nd:YAG lasers to levels required for coherent communication. Monolithic nonplanar ring oscillators constructed from solid pieces of the laser material provide better than 10 kHz frequency stability over 0.1 sec intervals. We have used active feedback stabilization of the cavity length of these lasers to demonstrate 0.3 Hz frequency stabilization relative to a reference cavity. We have performed experiments and analysis to show that optical parametric oscillators (OPO's) reproduce the frequency stability of the pump laser in outputs that can be tuned to arbitrary wavelengths. Another measurement performed in this program has demonstrated the sub-shot-noise character of correlations of the fluctuations in the twin output of OPO's. Measurements of nonlinear optical coefficients by phase-matched second harmonic generation are helping to resolve inconsistency in these important parameters.

Modeling of Adaptive Optics-Based Free-Space Communications Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilks, S C; Morris, J R; Brase, J M

2002-08-06

We introduce a wave-optics based simulation code written for air-optic laser communications links, that includes a detailed model of an adaptive optics compensation system. We present the results obtained by this model, where the phase of a communications laser beam is corrected, after it propagates through a turbulent atmosphere. The phase of the received laser beam is measured using a Shack-Hartmann wavefront sensor, and the correction method utilizes a MEMS mirror. Strehl improvement and amount of power coupled to the receiving fiber for both 1 km horizontal and 28 km slant paths are presented.

High bandwidth electro-optic technology for intersatellite optical communications

NASA Technical Reports Server (NTRS)

Krainak, Michael A.

1992-01-01

The research and development of electronic and electro-optic components for geosynchronous and low earth orbiting satellite optical high bandwidth communications at the NASA-Goddard Space Flight Center is reviewed. Intersatellite optical communications retains a strong reliance on microwave circuit technology in several areas - the microwave to optical interface, the laser transmitter modulation driver and the optical receiver. A microwave to optical interface is described requiring high bandwidth electronic downconverters and demodulators. Electrical bandwidth and current drive requirements for the laser modulation driver for three laser alternatives are discussed. Bandwidth and noise requirements are presented for optical receiver architectures.

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.

The C3PO project: a laser communication system concept for small satellites

NASA Astrophysics Data System (ADS)

d'Humières, Benoît; Esmiller, Bruno; Gouy, Yann; Steck, Emilie; Quintana, Crisanto; Faulkner, Graham; O'Brien, Dominic; Sproll, Fabian; Wagner, Paul; Hampf, Daniel; Riede, Wolfgang; Salter, Michael; Wang, Qin; Platt, Duncan; Jakonis, Darius; Piao, Xiaoyu; Karlsson, Mikael; Oberg, Olof; Petermann, Ingemar; Michalkiewicz, Aneta; Krezel, Jerzy; Debowska, Anna; Thueux, Yoann

2017-02-01

The satellite market is shifting towards smaller (micro and nanosatellites), lowered mass and increased performance platforms. Nanosatellites and picosatellites have been used for a number of new, innovative and unique payloads and missions. This trend requires new concepts for a reduced size, a better performance/weight ratio and a reduction of onboard power consumption. In this context, disruptive technologies, such as laser-optical communication systems, are opening new possibilities. This paper presents the C3PO1 system, "advanced Concept for laser uplink/ downlink CommuniCation with sPace Objects", and the first results of the development of its key technologies. This project targets the design of a communications system that uses a ground-based laser to illuminate a satellite, and a Modulating Retro-Reflector (MRR) to return a beam of light modulated by data to the ground. This enables a downlink, without a laser source on the satellite. This architecture suits well to small satellite applications so as high data rates are potentially provided with very low board mass. C3PO project aims to achieve data rates of 1Gbit/s between LEO satellites and Earth with a communication payload mass of less than 1kilogram. In this paper, results of the initial experiments and demonstration of the key technologies will be shown.

Star Tracker Performance Estimate with IMU

NASA Technical Reports Server (NTRS)

Aretskin-Hariton, Eliot D.; Swank, Aaron J.

2015-01-01

A software tool for estimating cross-boresight error of a star tracker combined with an inertial measurement unit (IMU) was developed to support trade studies for the Integrated Radio and Optical Communication project (iROC) at the National Aeronautics and Space Administration Glenn Research Center. Typical laser communication systems, such as the Lunar Laser Communication Demonstration (LLCD) and the Laser Communication Relay Demonstration (LCRD), use a beacon to locate ground stations. iROC is investigating the use of beaconless precision laser pointing to enable laser communication at Mars orbits and beyond. Precision attitude knowledge is essential to the iROC mission to enable high-speed steering of the optical link. The preliminary concept to achieve this precision attitude knowledge is to use star trackers combined with an IMU. The Star Tracker Accuracy (STAcc) software was developed to rapidly assess the capabilities of star tracker and IMU configurations. STAcc determines the overall cross-boresight error of a star tracker with an IMU given the characteristic parameters: quantum efficiency, aperture, apparent star magnitude, exposure time, field of view, photon spread, detector pixels, spacecraft slew rate, maximum stars used for quaternion estimation, and IMU angular random walk. This paper discusses the supporting theory used to construct STAcc, verification of the program and sample results.

Performance of a laser microsatellite network with an optical preamplifier.

PubMed

Arnon, Shlomi

2005-04-01

Laser satellite communication (LSC) uses free space as a propagation medium for various applications, such as intersatellite communication or satellite networking. An LSC system includes a laser transmitter and an optical receiver. For communication to occur, the line of sight of the transmitter and the receiver must be aligned. However, mechanical vibration and electronic noise in the control system reduce alignment between the transmitter laser beam and the receiver field of view (FOV), which results in pointing errors. The outcome of pointing errors is fading of the received signal, which leads to impaired link performance. An LSC system is considered in which the optical preamplifier is incorporated into the receiver, and a bit error probability (BEP) model is derived that takes into account the statistics of the pointing error as well as the optical amplifier and communication system parameters. The model and the numerical calculation results indicate that random pointing errors of sigma(chi)2G > 0.05 penalize communication performance dramatically for all combinations of optical amplifier gains and noise figures that were calculated.

Synchronization and bidirectional communication without delay line using strong mutually coupled semiconductor lasers

NASA Astrophysics Data System (ADS)

Li, Guang-Hui; Wang, An-Bang; Feng, Ye; Wang, Yang

2010-07-01

This paper numerically demonstrates synchronization and bidirectional communication without delay line by using two semiconductor lasers with strong mutual injection in a face-to-face configuration. These results show that both of the two lasers' outputs synchronize with their input chaotic carriers. In addition, simulations demonstrate that this kind of synchronization can be used to realize bidirectional communications without delay line. Further studies indicate that within a small deviation in message amplitudes of two sides (±6%), the message can be extracted with signal-noise-ratio more than 10 dB; and the signal-noise-ratio is extremely sensitive to the message rates mismatch of two sides, which may be used as a key of bidirectional communication.

Aerospace laser communications technology as enabler for worldwide quantum key distribution

NASA Astrophysics Data System (ADS)

Moll, Florian; Weinfurter, Harald; Rau, Markus; Schmidt, Christopher; Melén, Gwen; Vogl, Tobias; Nauerth, Sebastian; Fuchs, Christian

2016-04-01

A worldwide growing interest in fast and secure data communications pushes technology development along two lines. While fast communications can be realized using laser communications in fiber and free-space, inherently secure communications can be achieved using quantum key distribution (QKD). By combining both technologies in a single device, many synergies can be exploited, therefore reducing size, weight and power of future systems. In recent experiments we demonstrated quantum communications over large distances as well as between an aircraft and a ground station which proved the feasibility of QKD between moving partners. Satellites thus may be used as trusted nodes in combination with QKD receiver stations on ground, thereby enabling fast and secure communications on a global scale. We discuss the previous experiment with emphasis on necessary developments to be done and corresponding ongoing research work of German Aerospace Center (DLR) and Ludwig Maximilians University Munich (LMU). DLR is performing research on satellite and ground terminals for the high-rate laser communication component, which are enabling technologies for the QKD link. We describe the concept and hardware of three generations of OSIRIS (Optical High Speed Infrared Link System) laser communication terminals for low Earth orbiting satellites. The first type applies laser beam pointing solely based on classical satellite control, the second uses an optical feedback to the satellite bus and the third, currently being in design phase, comprises of a special coarse pointing assembly to control beam direction independent of satellite orientation. Ongoing work also targets optical terminals for CubeSats. A further increase of beam pointing accuracy can be achieved with a fine pointing assembly. Two ground stations will be available for future testing, an advanced stationary ground station and a transportable ground station. In parallel the LMU QKD source size will be reduced by more than an order of magnitude thereby simplifying its integration into future free-space optical communication links with CubeSats.

Research on the optoacoustic communication system for speech transmission by variable laser-pulse repetition rates

NASA Astrophysics Data System (ADS)

Jiang, Hongyan; Qiu, Hongbing; He, Ning; Liao, Xin

2018-06-01

For the optoacoustic communication from in-air platforms to submerged apparatus, a method based on speech recognition and variable laser-pulse repetition rates is proposed, which realizes character encoding and transmission for speech. Firstly, the theories and spectrum characteristics of the laser-generated underwater sound are analyzed; and moreover character conversion and encoding for speech as well as the pattern of codes for laser modulation is studied; lastly experiments to verify the system design are carried out. Results show that the optoacoustic system, where laser modulation is controlled by speech-to-character baseband codes, is beneficial to improve flexibility in receiving location for underwater targets as well as real-time performance in information transmission. In the overwater transmitter, a pulse laser is controlled to radiate by speech signals with several repetition rates randomly selected in the range of one to fifty Hz, and then in the underwater receiver laser pulse repetition rate and data can be acquired by the preamble and information codes of the corresponding laser-generated sound. When the energy of the laser pulse is appropriate, real-time transmission for speaker-independent speech can be realized in that way, which solves the problem of underwater bandwidth resource and provides a technical approach for the air-sea communication.

Spectral filters for laser communications

NASA Technical Reports Server (NTRS)

Shaik, K.

1991-01-01

Optical communication systems must perform reliabily under strong background light interference. Since the transmitting lasers operate within a narrow spectral band, high signal to noise ratios can be achieved when narrowband spectral optical filters can be used to reject out of band light. Here, a set of general requirements for such filters are developed, and an overview is given of suitable spectral filter technologies for optical communication systems.

Free Space Laser Communications

NASA Technical Reports Server (NTRS)

Lesh, James

2000-01-01

This presentation concerns the use of Laser communication for deep space applications. The presentation reviews the problems with electromagnetic beams and then the advantages and disadvantages of the use of optical communication. The presentation then reviews some of the spacecraft technology with pictures of some of the devices. The ground reception systems and the simplified link calculation are also reviewed. Recent and planned demonstration projects are also reviewed.

High-power 0.87-micron channel substrate planar lasers for spaceborne communications

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Stewart, T. R.; Gilbert, D. B.; Slavin, S. E.; Carlin, D. B.

1988-01-01

High-power single-mode channeled-substrate planar AlGaAs diode lasers are being developed for reliable high-power operation for use as sources in spaceborne optical communication systems. The CSP laser structure has been optimized for operation at an emission wavelength of 870 nm. Such devices have exhibited output powers in excess of 80 mW CW at an operating temperature of 80 C.

Laser Technology

NASA Technical Reports Server (NTRS)

1989-01-01

Amoco Laser Company, a subsidiary of Amoco Corporation, has developed microlasers for the commercial market based on a JPL concept for optical communications over interplanetary distances. Lasers emit narrow, intense beams of light or other radiation. The beams transmit communication signals, drill, cut or melt materials or remove diseased body tissue. The microlasers cover a broad portion of the spectrum, and performance is improved significantly. Current applications include medical instrumentation, color separation equipment, telecommunications, etc.

Integrated Photonic Orbital Angular Momentum Multiplexing and Demultiplexing on Chip

DTIC Science & Technology

2014-10-31

OAM free space coherent communication link testbed. ECL: external cavity laser . EDFA: erbium-doped fiber amplifier. PC: polarization controller. ATT...wave (cw) laser centered at 1540 nm, followed by an erbium-doped fiber amplifier (EDFA), an I/Q modulator, and another EDFA. The I/Q modulator was...communication link testbed. ECL: external cavity laser . EDFA: erbium-doped fiber amplifier. PC: polarization controller. ATT: attenuator. BPF: bandpass filter

Executive summary. [application of laser oriented and radio frequency techniques for space communication

NASA Technical Reports Server (NTRS)

1973-01-01

The scope of Technology Forecasting for Space Communications is very wide, covering virtually every technology that can directly or indirectly affect space communications. The assigned effort, however, was directed toward a series of studies which individually examined important aspects of space communications and which collectively was interrelated. The contributions of the individual tasks and their interrelationship are indicated. The total effort of the tasks was fairly evenly divided between laser oriented and radio frequency tasks. The investigations show that laser communications have a current state of the art which would allow operational systems to be implemented in the 1975 to 1980 time frame. Further, these systems, when operated over ranges in the order of synchronous ranges (42,000 km)and transmitting data rates of 10 to the 8th power 10 to the 9th power bits per second will have a smaller total weight impact on a spacecraft than do radio systems.

Experimental multiplexing of quantum key distribution with classical optical communication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Liu-Jun; Chen, Luo-Kan; Ju, Lei

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 themore » 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.« less

Statistical characterization of fluctuations of a laser beam transmitted through a random air-water interface: new results from a laboratory experiment

NASA Astrophysics Data System (ADS)

Majumdar, Arun K.; Land, Phillip; Siegenthaler, John

2014-10-01

New results for characterizing laser intensity fluctuation statistics of a laser beam transmitted through a random air-water interface relevant to underwater communications are presented. A laboratory watertank experiment is described to investigate the beam wandering effects of the transmitted beam. Preliminary results from the experiment provide information about histograms of the probability density functions of intensity fluctuations for different wind speeds measured by a CMOS camera for the transmitted beam. Angular displacements of the centroids of the fluctuating laser beam generates the beam wander effects. This research develops a probabilistic model for optical propagation at the random air-water interface for a transmission case under different wind speed conditions. Preliminary results for bit-error-rate (BER) estimates as a function of fade margin for an on-off keying (OOK) optical communication through the air-water interface are presented for a communication system where a random air-water interface is a part of the communication channel.

Semiconductor Lasers and Their Application in Optical Fiber Communication.

ERIC Educational Resources Information Center

Agrawal, Govind P.

1985-01-01

Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

Remotely-interrogated high data rate free space laser communications link

DOEpatents

Ruggiero, Anthony J [Livermore, CA

2007-05-29

A system and method of remotely extracting information from a communications station by interrogation with a low power beam. Nonlinear phase conjugation of the low power beam results in a high power encoded return beam that automatically tracks the input beam and is corrected for atmospheric distortion. Intracavity nondegenerate four wave mixing is used in a broad area semiconductor laser in the communications station to produce the return beam.

Teleoperation of an experimental mobile vehicle via a free-space optical laser line-of-sight communication link for use in nuclear power plant environments

NASA Astrophysics Data System (ADS)

Girach, Khalid; Bouazza-Marouf, K.; Kerr, David; Hewit, Jim

1994-11-01

The paper describes the investigations carried out to implement a line of sight control and communication link for a mobile robot vehicle for use in structured nuclear semi-hazardous environments. Line of sight free space optical laser communication links for remote teleoperation have important applications in hazardous environments. They have certain advantages over radio/microwave links and umbilical control such as greater protection against generation of and susceptance to electro-magnetic fields. The cable-less environment provides increased integrity and mechanical freedom to the mobile robot. However, to maintain the communication link, continuous point and tracking is required between the base station and the mobile vehicle. This paper presents a novel two ended optical tracking system utilizing the communication laser beams and photodetectors. The mobile robot is a six wheel drive vehicle with a manipulator arm which can operate in a variety of terrain. The operator obtains visual feedback information from cameras placed on the vehicle. From this information, the speed and direction of the vehicle can be controlled from a joystick panel. We describe the investigations carried out for the communication of analogue video and digital data signals over the laser link for speed and direction control.

Development of a wideband pulse quaternary modulation system. [for an operational 400 Mbps baseband laser communication system

NASA Technical Reports Server (NTRS)

Federhofer, J. A.

1974-01-01

Laboratory data verifying the pulse quaternary modulation (PQM) theoretical predictions is presented. The first laboratory PQM laser communication system was successfully fabricated, integrated, tested and demonstrated. System bit error rate tests were performed and, in general, indicated approximately a 2 db degradation from the theoretically predicted results. These tests indicated that no gross errors were made in the initial theoretical analysis of PQM. The relative ease with which the entire PQM laboratory system was integrated and tested indicates that PQM is a viable candidate modulation scheme for an operational 400 Mbps baseband laser communication system.

Investigation of High Linearity DFB Lasers for Analog Communications

DTIC Science & Technology

1998-02-01

personal communication systems (PCS) service and phased array radar. In this thesis, we examine the dynamic range and distortion for a Fujitsu DFB laser. We...PCS) service and phased array radar. In this thesis, we examine the dynamic range and distortion for a Fujitsu DFB laser. We extract parameters from...is dependent upon the coupling coefficient, as discussed in Chapter 3. Spatial hole burning is more important at lower frequencies (owing to finite

Nd:YAG end pumped by semiconductor laser arrays for free space optical communications

NASA Technical Reports Server (NTRS)

Sipes, D. L., Jr.

1985-01-01

Preliminary experimental results are reported for a diode-pumped Nd:YAG laser employing a tightly focused end-pump geometry. The resonator configuration is planoconcave, with the pumped end of the Nd:YAG rod being coated for high reflection at 1.06 microns. This geometry rectifies nearly all the inefficiencies plaguing side-pumped schemes. This laser is further considered as a candidate for optical communication over the deep space channel.

Fiber distributed feedback laser

NASA Technical Reports Server (NTRS)

Elachi, C.; Evans, G. A.; Yeh, C. (Inventor)

1976-01-01

Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

PubMed

Yura, Harold T; Fields, Renny A

2011-06-20

Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

NASA Technical Reports Server (NTRS)

Wang, Charles P. (Editor)

1993-01-01

Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

Group III-arsenide-nitride long wavelength laser diodes

NASA Astrophysics Data System (ADS)

Coldren, Christopher W.

Semiconductor laser diodes transmitting data over silica optical fiber form the backbone of modern day communications systems, enabling terabit per second data transmission over hundreds to thousands of kilometers of distance. The wavelength of emission of the transmission semiconductor laser diode is a critical parameter that determines the performance of the communications system. In high performance fiber optic communications systems, lasers emitting at 1300nm and 1550nm are used because of the low loss and distortion properties of the fiber in these spectral windows. The available lasers today that operate in these fiber optic transmission windows suffer from high cost and poor performance under the typical environmental conditions and require costly and unreliable cooling systems. This dissertation presents work that demonstrates that it is possible to make lasers devices with 1300nm laser emission that are compatible with low cost and operation under extreme operating conditions. The key enabling technology developed is a novel semiconductor material based structure. A group III-Arsenide-Nitride quantum well structure was developed that can be grown expitaxially on GaAs substrates. The properties of this group III-Arsenide-Nitride structure allowed high performance edge emitting and vertical cavity surface emitting lasers to be fabricated which exhibited low threshold currents and low sensitivity to operating temperature.

Optical overview and qualification of the LLCD space terminal

NASA Astrophysics Data System (ADS)

DeVoe, C. E.; Pillsbury, A. D.; Khatri, F.; Burnside, J. M.; Raudenbush, A. C.; Petrilli, L. J.; Williams, T.

2017-11-01

In October 2013 the Lunar Laser Communications Demonstration (LLCD) made communications history by successfully demonstrating 622 megabits per second laser communication from the moon's orbit to earth. The LLCD consisted of the Lunar Laser Communication Space Terminal (LLST), developed by MIT Lincoln Laboratory, mounted on NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft and a primary ground terminal located in New Mexico, the Lunar Laser Communications Ground Terminal (LLGT), and two alternate ground terminals. This paper presents the optical layout of the LLST, the approach for testing the optical subsystems, and the results of the optical qualification of the LLST. Also described is the optical test set used to qualify the LLST. The architecture philosophy for the optics was to keep a small, simple optical backend that provided excellent boresighting and high isolation between the optical paths, high quality wavefront on axis, with minimal throughput losses on all paths. The front end large optics consisted of a Cassegrain 107mm telescope with an f/0.7 parabolic primary mirror and a solar window to reduce the thermal load on the telescope and to minimize background light received at the sensors.

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.

Simultaneous Laser Ranging and Communication from an Earth-Based Satellite Laser Ranging Station to the Lunar Reconnaissance Orbiter in Lunar Orbit

NASA Technical Reports Server (NTRS)

Sun, Xiaoli; Skillman, David R.; Hoffman, Evan D.; Mao, Dandan; McGarry, Jan F.; Neumann, Gregory A.; McIntire, Leva; Zellar, Ronald S.; Davidson, Frederic M.; Fong, Wai H.;

Beaconless Pointing for Deep-Space Optical Communication

NASA Technical Reports Server (NTRS)

Swank, Aaron J.; Aretskin-Hariton, Eliot; Le, Dzu K.; Sands, Obed S.; Wroblewski, Adam

2016-01-01

Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.

Radiation-hard mid-power booster optical fiber amplifiers for high-speed digital and analogue satellite laser communication links

NASA Astrophysics Data System (ADS)

Stampoulidis, L.; Kehayas, E.; Stevens, G.; Henwood-Moroney, L.; Hosking, P.; Robertson, A.

2017-11-01

Optical laser communications (OLC) has been identified as the technology to enable high-data rate, secure links between and within satellites, as well as between satellites and ground stations with decreased mass, size, and electrical power compared to traditional RF technology.

Quaternary pulse position modulation electronics for free-space laser communications

NASA Technical Reports Server (NTRS)

Budinger, J. M.; Kerslake, S. D.; Nagy, L. A.; Shalkhauser, M. J.; Soni, N. J.; Cauley, M. A.; Mohamed, J. H.; Stover, J. B.; Romanofsky, R. R.; Lizanich, P. J.

1991-01-01

The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (GPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.

Quaternary pulse position modulation electronics for free-space laser communications

NASA Technical Reports Server (NTRS)

Budinger, J. M.; Kerslake, S. D.; Nagy, L. A.; Shalkhauser, M. J.; Soni, N. J.; Cauley, M. A.; Mohamed, J. H.; Stover, J. B.; Romanofsky, R. R.; Lizanich, P. J.

1991-01-01

The development of a high data-rate communications electronic subsystem for future application in free-space, direct-detection laser communications is described. The dual channel subsystem uses quaternary pulse position modulation (QPPM) and operates at a throughput of 650 megabits per second. Transmitting functions described include source data multiplexing, channel data multiplexing, and QPPM symbol encoding. Implementation of a prototype version in discrete gallium arsenide logic, radiofrequency components, and microstrip circuitry is presented.

Laser Transmitter Aims At Laser Beacon

NASA Technical Reports Server (NTRS)

Hemmati, Hamid; Lesh, James R.

1993-01-01

Transmitter part of developmental optical communication system. Compact, lightweight, partially-self-aiming laser transmitter built to verify some capabilities of developmental free-space optical communication system. Design capable of providing 0.5 Mbps data return over range equal to Moon-Earth distance. Breadboard of transmitting terminal constructed and tested in laboratory. Prototype transmitter includes receiving circuitry that keeps it aimed at beacon, once brought into initial alignment within about 1.7 degrees of line of sight to beacon.

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.

NFIRE-to-TerraSAR-X laser communication results: satellite pointing, disturbances, and other attributes consistent with successful performance

NASA Astrophysics Data System (ADS)

Fields, Renny; Lunde, Carl; Wong, Robert; Wicker, Josef; Kozlowski, David; Jordan, John; Hansen, Brian; Muehlnikel, Gerd; Scheel, Wayne; Sterr, Uwe; Kahle, Ralph; Meyer, Rolf

2009-05-01

Starting in late 2007 and continuing through the present, NFIRE (Near-Field Infrared Experiment), a Missile Defense Agency (MDA) experimental satellite and TerraSAR-X, a German commercial SAR satellite have been conducting mutual crosslink experiments utilizing a secondary laser communication payload built by Tesat-Spacecom. The narrow laser beam-widths and high relative inter-spacecraft velocities for the two low-earth-orbiting satellites imply strict pointing control and dynamics aboard both vehicles. The satellites have achieved rapid communication acquisition times and maintained communication for hundreds of seconds before losing line of sight to the counter satellite due to earth blockage. Through post-mission analysis and other related telemetry we will show results for pointing accuracy, disturbance environments and pre-engagement prediction requirements that support successful and reliable operations.

The research of adaptive-exposure on spot-detecting camera in ATP system

NASA Astrophysics Data System (ADS)

Qian, Feng; Jia, Jian-jun; Zhang, Liang; Wang, Jian-Yu

2013-08-01

High precision acquisition, tracking, pointing (ATP) system is one of the key techniques of laser communication. The spot-detecting camera is used to detect the direction of beacon in laser communication link, so that it can get the position information of communication terminal for ATP system. The positioning accuracy of camera decides the capability of laser communication system directly. So the spot-detecting camera in satellite-to-earth laser communication ATP systems needs high precision on target detection. The positioning accuracy of cameras should be better than +/-1μ rad . The spot-detecting cameras usually adopt centroid algorithm to get the position information of light spot on detectors. When the intensity of beacon is moderate, calculation results of centroid algorithm will be precise. But the intensity of beacon changes greatly during communication for distance, atmospheric scintillation, weather etc. The output signal of detector will be insufficient when the camera underexposes to beacon because of low light intensity. On the other hand, the output signal of detector will be saturated when the camera overexposes to beacon because of high light intensity. The calculation accuracy of centroid algorithm becomes worse if the spot-detecting camera underexposes or overexposes, and then the positioning accuracy of camera will be reduced obviously. In order to improve the accuracy, space-based cameras should regulate exposure time in real time according to light intensity. The algorithm of adaptive-exposure technique for spot-detecting camera based on metal-oxide-semiconductor (CMOS) detector is analyzed. According to analytic results, a CMOS camera in space-based laser communication system is described, which utilizes the algorithm of adaptive-exposure to adapting exposure time. Test results from imaging experiment system formed verify the design. Experimental results prove that this design can restrain the reduction of positioning accuracy for the change of light intensity. So the camera can keep stable and high positioning accuracy during communication.

Development of a safe ground to space laser propagation system for the optical communications telescope laboratory

NASA Technical Reports Server (NTRS)

Wu, Janet P.

2003-01-01

Furthering pursuits in high bandwidth communications to future NASA deep space and neat-Earth probes, the Jet Propulsion Laboratory (JPL) is building the Optical communications Telescope Laboratory (OCTL) atop Table Mountain in Southern California. This R&D optical antenna will be used to develop optical communication strategies for future optical ground stations. Initial experiments to be conducted include propagating high-powered, Q-switched laser beams to retro-reflecting satellites. Yet laser beam propagation from the ground to space is under the cognizance of various government agencies, namely: the Occupational Safety and Health Administration (ISHA) that is responsible for protecting workforce personnel; the Federal Aviation Administration (FAA) responsible for protecting pilots and aircraft; and the Laser Clearinghouse of Space Command responsible for protecting space assets. To ensure that laser beam propagation from the OCTL and future autonomously operated ground stations comply with the guidelines of these organizations, JPL is developing a multi-tiered safety system that will meet the coordination, monitoring, and reporting functions required by the agencies. At Tier 0, laser operators will meet OSHA safety standards for protection and access to the high power lasers area will be restricted and interlocked. Tier 1, the area defined from the telescope dome out to a range of 3.4-km, will utilize long wave infrared camera sensors to alert operators of at risk aircraft in the FAA controlled airspace. Tier 2, defined to extend from 3.4-km out to the aircraft service ceiling in FAA airspace, will detect at risk aircraft by radar. Lastly, beam propagation into space, defined as Tier 3, will require coordination with the Laser Clearinghouse. A detailed description of the four tiers is presented along with the design of the integrated monitoring and beam transmission control system.

VideoBeam portable laser communicator

NASA Astrophysics Data System (ADS)

Mecherle, G. Stephen; Holcomb, Terry L.

1999-01-01

A VideoBeamTM portable laser communicator has been developed which provides full duplex communication links consisting of high quality analog video and stereo audio. The 3.2-pound unit resembles a binocular-type form factor and has an operational range of over two miles (clear air) with excellent jam-resistance and low probability of interception characteristics. The VideoBeamTM unit is ideally suited for numerous military scenarios, surveillance/espionage, industrial precious mineral exploration, and campus video teleconferencing applications.

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.

Coherent communication link using diode-pumped lasers

NASA Technical Reports Server (NTRS)

Kane, Thomas J.; Wallace, Richard W.

1989-01-01

Work toward developing a diffraction limited, single frequency, modulated transmitter suitable for coherent optical communication or direct detection communication is discussed. Diode pumped, monolithic Nd:YAG nonplanar ring oscillators were used as the carrier beam. An external modulation technique which can handle high optical powers, has moderate modulation voltage, and which can reach modulation rates of 1 GHz was invented. Semiconductor laser pumped solid-state lasers which have high output power (0.5 Watt) and which oscillate at a single frequency, in a diffraction limited beam, at the wavelength of 1.06 microns were built. A technique for phase modulating the laser output by 180 degrees with a 40-volt peak to peak driving voltage is demonstrated. This technique can be adapted for amplitude modulation of 100 percent with the same voltage. This technique makes use of a resonant bulk modulator, so it does not have the power handling limitations of guided wave modulators.

Coherent detection of position errors in inter-satellite laser communications

NASA Astrophysics Data System (ADS)

Xu, Nan; Liu, Liren; Liu, De'an; Sun, Jianfeng; Luan, Zhu

2007-09-01

Due to the improved receiver sensitivity and wavelength selectivity, coherent detection became an attractive alternative to direct detection in inter-satellite laser communications. A novel method to coherent detection of position errors information is proposed. Coherent communication system generally consists of receive telescope, local oscillator, optical hybrid, photoelectric detector and optical phase lock loop (OPLL). Based on the system composing, this method adds CCD and computer as position error detector. CCD captures interference pattern while detection of transmission data from the transmitter laser. After processed and analyzed by computer, target position information is obtained from characteristic parameter of the interference pattern. The position errors as the control signal of PAT subsystem drive the receiver telescope to keep tracking to the target. Theoretical deviation and analysis is presented. The application extends to coherent laser rang finder, in which object distance and position information can be obtained simultaneously.

Full-Duplex Digital Communication on a Single Laser Beam

NASA Technical Reports Server (NTRS)

Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

2006-01-01

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Terre des Lasers: the new Aquitaine outreach and communication center in photonics

NASA Astrophysics Data System (ADS)

Prulhiere, Jean Paul; Sarger, Laurent

2009-06-01

The competitive cluster "Route des Lasers" has been labeled by the French Government in July 2005. In this context, it has launched in September 2005, in cooperation with Commissariat à l'Energie Atomique (CEA) and Regional Council a project involving scientific exhibitions, called "Terre des Lasers ®", in order to create an exhibition and an area of communication and science discovery or a very large target (public, school, industry) in the fields of optics, lasers, optronics and imaging. This initiative is part of the strategy of the "Route des Lasers" center which aims to promote technologies developed in the areas of photonics, targeting in particular children and teenagers and their awareness for this particular industrial and scientific topic.

Fourier Transform Spectrometer System

NASA Technical Reports Server (NTRS)

Campbell, Joel F. (Inventor)

2014-01-01

A Fourier transform spectrometer (FTS) data acquisition system includes an FTS spectrometer that receives a spectral signal and a laser signal. The system further includes a wideband detector, which is in communication with the FTS spectrometer and receives the spectral signal and laser signal from the FTS spectrometer. The wideband detector produces a composite signal comprising the laser signal and the spectral signal. The system further comprises a converter in communication with the wideband detector to receive and digitize the composite signal. The system further includes a signal processing unit that receives the composite signal from the converter. The signal processing unit further filters the laser signal and the spectral signal from the composite signal and demodulates the laser signal, to produce velocity corrected spectral data.

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 maintains the phase lock between the two laser sources. The novelty and key significance of this work is that the carrier phase information can be harnessed within an optical communication link based on PPM-PCD architecture. This technology development could lead to quantum-limited efficient performance within the communication link itself, as well as enable high-resolution optical tracking capabilities for planetary science and spacecraft navigation.

0.87-micron CSP diode lasers for spaceborne communications. [channeled-substrate-planar

NASA Technical Reports Server (NTRS)

Carlin, D. B.; Pultz, G. N.; Goldstein, B.

1987-01-01

Index-guided channeled-substrate-planar (CSP) AlGaAs diode lasers are being developed for reliable, high-power operation for use as sources in spaceborne optical communications systems. Although most work on this AlGaAs structure has been aimed at optimizing performance at output wavelengths less than 8400 A, emission in the 8700 A regime is also of interest. In particular, such wavelengths are required for use in the direct detection laser transceiver to be incorporated into NASA's advanced communications technology satellite, in order to avoid absorption of the light by the atmosphere when communicating with ground-based terminals. Lowest order spatial mode and substantially single longitudinal mode output has been observed in 0.87-micron CSP devices in excess of 50 mW cw and 100 mW 50 percent duty-cycle, with rms phase-front aberrations measured to be about lambda/40.

The Laser Communications Relay and the Path to the Next Generation Near Earth Relay

NASA Technical Reports Server (NTRS)

Israel, David J.

2015-01-01

NASA Goddard Space Flight Center is currently developing the Laser Communications Relay Demonstration (LCRD) as a Path to the Next Generation Near Earth Space Communication Network. The current NASA Space Network or Tracking and Data Relay Satellite System is comprised of a constellation of Tracking and Data Relay Satellites (TDRS) in geosynchronous orbit and associated ground stations and operation centers. NASA is currently targeting a next generation of relay capability on orbit in the 2025 timeframe.

Laser diode combining for free space optical communication

NASA Technical Reports Server (NTRS)

Mecherle, G. Stephen

1986-01-01

The maximization of photon delivery to a distant collector in free space optical communications systems calls for a laser diode-combining technique employing wavelength and/or polarization as the bases of its operation. Design considerations for such a combiner encompass high throughput efficiency, diffraction-limited angular divergence, and reasonable volume constraints. Combiners are presently found to require a generalized Strehl ratio concept which includes relative source misalignment; diffraction grating combiners may have a limited number of laser sources which can meet spectral requirements. Methods for the incorporation of a combiner into a communication system are compared. Power combining is concluded to be the best tradeoff of performance and complexity for all systems, except those that are severely limited by either background radiation or component bandwidth.

Novel quantum well gallium arsenide-based lasers for all transmission windows in optical communication

NASA Astrophysics Data System (ADS)

Tansu, Nelson

The thesis covers the development of novel active regions for high-performance edge-emitting lasers (EEL) and vertical cavity surface-emitting lasers (VCSELs) in optical communication. Three main themes of the thesis cover the design, fabrication, and physics of the novel and alternative active regions for GaAs-based VCSELs for the three optical communications windows at wavelength regimes of 850-nm, 1300-nm, and 1500-nm, with the emphases on the 1300-nm InGaAsN QW GaAs-based active regions and on the novel design of 1500-nm GaAs-based active regions. The studies include the utilization of compressively-strained InGaAsP quantum well (QW) active regions for the 850-nm VCSELs. The research on the long-wavelength lasers covers the design, growth, temperature analysis, carrier transport, and gain analysis of the InGaAsN (lambda = 1.3 mum) quantum well lasers. The novel and original design of the GaAsSb-(In)GaAsN type-II QWs to achieve 1500--3000 nm GaAs-based active regions is discussed in detail.

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.

Study and design of laser communications system for space shuttle

NASA Technical Reports Server (NTRS)

1973-01-01

The design, development and operation are described of the laser communications system developed for potential space shuttle application. A brief study was conducted to identify the need, if any, for narrow bandwidth space-to-space communication on the shuttle vehicles. None have been specifically identified that could not be accommodated with existing equipments. The key technical features developed in this hardware are the conically scanned tracker for optimized track while communicating with a single detector, and the utilization of a common optical carrier frequency for both transmission and detection. This latter feature permits a multiple access capability so that several transceivers can communicate with one another. The conically scanned tracker technique allows the received signal energy to be efficiently divided between the tracking and communications functions within a common detector.

Communication scheme using a hyperchaotic semiconductor laser model: Chaos shift key revisited

NASA Astrophysics Data System (ADS)

Fataf, N. A. A.; Palit, Sanjay Kumar; Mukherjee, Sayan; Said, M. R. M.; Son, Doan Hoai; Banerjee, Santo

2017-11-01

Based on the Maxwell-Bloch equations, we considered a five-dimensional ODE system, describing the dynamics of a semiconductor laser. The system has rich dynamics with multi-periodic, chaotic and hyperchaotic states. In this analysis, we have investigated the hyperchaotic nature of the aforesaid model and proposed a communication scheme, the generalized form of chaos shift keys, where the coupled systems do not need to be in the synchronized state. The results are implemented with the hyperchaotic laser model followed by a comprehensive security analysis.

Creation of backdoors in quantum communications via laser damage

NASA Astrophysics Data System (ADS)

Makarov, Vadim; Bourgoin, Jean-Philippe; Chaiwongkhot, Poompong; Gagné, Mathieu; Jennewein, Thomas; Kaiser, Sarah; Kashyap, Raman; Legré, Matthieu; Minshull, Carter; Sajeed, Shihan

2016-09-01

Practical quantum communication (QC) protocols are assumed to be secure provided implemented devices are properly characterized and all known side channels are closed. We show that this is not always true. We demonstrate a laser-damage attack capable of modifying device behavior on demand. We test it on two practical QC systems for key distribution and coin tossing, and show that newly created deviations lead to side channels. This reveals that laser damage is a potential security risk to existing QC systems, and necessitates their testing to guarantee security.

Experimental demonstration of a retro-reflective laser communication link on a mobile platform

NASA Astrophysics Data System (ADS)

Nikulin, Vladimir V.; Malowicki, John E.; Khandekar, Rahul M.; Skormin, Victor A.; Legare, David J.

2010-02-01

Successful pointing, acquisition, and tracking (PAT) are crucial for the implementation of laser communication links between ground and aerial vehicles. This technology has advantages over the traditional radio frequency communication, thus justifying the research efforts presented in this paper. The authors have been successful in the development of a high precision, agile, digitally controlled two-degree-of-freedom electromechanical system for positioning of optical instruments, cameras, telescopes, and communication lasers. The centerpiece of this system is a robotic manipulator capable of singularity-free operation throughout the full hemisphere range of yaw/pitch motion. The availability of efficient two-degree-of-freedom positioning facilitated the development of an optical platform stabilization system capable of rejecting resident vibrations with the angular and frequency range consistent with those caused by a ground vehicle moving on a rough terrain. This technology is being utilized for the development of a duplex mobile PAT system demonstrator that would provide valuable feedback for the development of practical laser communication systems intended for fleets of moving ground, and possibly aerial, vehicles. In this paper, a tracking system providing optical connectivity between stationary and mobile ground platforms is described. It utilizes mechanical manipulator to perform optical platform stabilization and initial beam positioning, and optical tracking for maintaining the line-of-sight communication. Particular system components and the challenges of their integration are described. The results of field testing of the resultant system under practical conditions are presented.

Computer program compatible with a laser nephelometer

NASA Technical Reports Server (NTRS)

Paroskie, R. M.; Blau, H. H., Jr.; Blinn, J. C., III

1975-01-01

The laser nephelometer data system was updated to provide magnetic tape recording of data, and real time or near real time processing of data to provide particle size distribution and liquid water content. Digital circuits were provided to interface the laser nephelometer to a Data General Nova 1200 minicomputer. Communications are via a teletypewriter. A dual Linc Magnetic Tape System is used for program storage and data recording. Operational programs utilize the Data General Real-Time Operating System (RTOS) and the ERT AIRMAP Real-Time Operating System (ARTS). The programs provide for acquiring data from the laser nephelometer, acquiring data from auxiliary sources, keeping time, performing real time calculations, recording data and communicating with the teletypewriter.

Laser Communications Relay Demonstration (LCRD) Update and the Path Towards Optical Relay Operations

NASA Technical Reports Server (NTRS)

Israel, David J.; Edwards, Bernard L.; Staren, John W.

2017-01-01

This paper provides a concept for an evolution of NASA's optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), 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). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.

Laser Communications Relay Demonstration (LCRD) Update and the Path Towards Optical Relay Operations

NASA Technical Reports Server (NTRS)

Israel, David J.; Edwards, Bernard L.; Staren, John W.

2017-01-01

This Presentation provides a concept for an evolution of NASAs optical communications near Earth relay architecture. NASA's Laser Communications Relay Demonstration (LCRD), a joint project between NASAs Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory - California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). LCRD will provide a minimum of two years of high data rate optical communications service experiments in geosynchronous orbit (GEO), following launch in 2019. This paper will provide an update of the LCRD mission status and planned capabilities and experiments, followed by a discussion of the path from LCRD to operational network capabilities.

Underwater speech communications with a modulated laser

NASA Astrophysics Data System (ADS)

Woodward, B.; Sari, H.

2008-04-01

A novel speech communications system using a modulated laser beam has been developed for short-range applications in which high directionality is an exploitable feature. Although it was designed for certain underwater applications, such as speech communications between divers or between a diver and the surface, it may equally be used for air applications. With some modification it could be used for secure diver-to-diver communications in the situation where untethered divers are swimming close together and do not want their conversations monitored by intruders. Unlike underwater acoustic communications, where the transmitted speech may be received at ranges of hundreds of metres omnidirectionally, a laser communication link is very difficult to intercept and also obviates the need for cables that become snagged or broken. Further applications include the transmission of speech and data, including the short message service (SMS), from a fixed installation such as a sea-bed habitat; and data transmission to and from an autonomous underwater vehicle (AUV), particularly during docking manoeuvres. The performance of the system has been assessed subjectively by listening tests, which revealed that the speech was intelligible, although of poor quality due to the speech algorithm used.

Near-IR laser frequency standard stabilized using FM-spectroscopy

NASA Astrophysics Data System (ADS)

Ružička, Bohdan; Číp, Ondřej; Lazar, Josef

2006-02-01

At the present time fiber-optics and optical communication are in rapid progress. Modern technologies such as DWDM (Dense Wavelength Division Multiplex) need precise stability of laser frequencies. According to this fact, requirements of new etalons of optical frequencies in the telecommunication band is rapidly growing. Lasers working in near infrared telecommunication band (1500-1600 nm) can be stabilized to 12C IIH II or 13C IIH II (acetylene) gas absorption lines. The acetylene gas absorption has been widely studied and accepted by international bodies of standardization as a primary wavelength reference in the near infrared band around 1550nm. Our aim was to design and develop a compact fibre optics laser system generating coherent light in near-JR band with high frequency stability (at least 1.10 -8). This system should become a base for realization of a primary frequency standard for optical communications in the Czech Republic. Such an etalon will be needed for calibration of wavelength-meters and spectral analysers for DWDM communication systems. We are co-operating with CMI (Czech Metrology Institute) on this project. We present stabilized laser system based on a single frequency DFB (Distributed Feedback) laser diode with a narrow spectral profile. The laser is pre-stabilized by means of the FM-spectroscopy on a passive resonator. Thanks to a fast feed-back loop we are able to improve spectral characteristics of the laser. The laser frequency is locked by a relatively slow second feed-back loop on an absorption line of acetylene vapour which is sealed in a cell under the optimised pressure.

Towards energy-efficient photonic interconnects

NASA Astrophysics Data System (ADS)

Demir, Yigit; Hardavellas, Nikos

2015-03-01

Silicon photonics have emerged as a promising solution to meet the growing demand for high-bandwidth, low-latency, and energy-efficient on-chip and off-chip communication in many-core processors. However, current silicon-photonic interconnect designs for many-core processors waste a significant amount of power because (a) lasers are always on, even during periods of interconnect inactivity, and (b) microring resonators employ heaters which consume a significant amount of power just to overcome thermal variations and maintain communication on the photonic links, especially in a 3D-stacked design. The problem of high laser power consumption is particularly important as lasers typically have very low energy efficiency, and photonic interconnects often remain underutilized both in scientific computing (compute-intensive execution phases underutilize the interconnect), and in server computing (servers in Google-scale datacenters have a typical utilization of less than 30%). We address the high laser power consumption by proposing EcoLaser+, which is a laser control scheme that saves energy by predicting the interconnect activity and opportunistically turning the on-chip laser off when possible, and also by scaling the width of the communication link based on a runtime prediction of the expected message length. Our laser control scheme can save up to 62 - 92% of the laser energy, and improve the energy efficiency of a manycore processor with negligible performance penalty. We address the high trimming (heating) power consumption of the microrings by proposing insulation methods that reduce the impact of localized heating induced by highly-active components on the 3D-stacked logic die.

DAZZLE project: UAV to ground communication system using a laser and a modulated retro-reflector

NASA Astrophysics Data System (ADS)

Thueux, Yoann; Avlonitis, Nicholas; Erry, Gavin

2014-10-01

The advent of the Unmanned Aerial Vehicle (UAV) has generated the need for reduced size, weight and power (SWaP) requirements for communications systems with a high data rate, enhanced security and quality of service. This paper presents the current results of the DAZZLE project run by Airbus Group Innovations. The specifications, integration steps and initial performance of a UAV to ground communication system using a laser and a modulated retro-reflector are detailed. The laser operates at the wavelength of 1550nm and at power levels that keep it eye safe. It is directed using a FLIR pan and tilt unit driven by an image processing-based system that tracks the UAV in flight at a range of a few kilometers. The modulated retro-reflector is capable of a data rate of 20Mbps over short distances, using 200mW of electrical power. The communication system was tested at the Pershore Laser Range in July 2014. Video data from a flying Octocopter was successfully transmitted over 1200m. During the next phase of the DAZZLE project, the team will attempt to produce a modulated retro-reflector capable of 1Gbps in partnership with the research institute Acreo1 based in Sweden. A high speed laser beam steering capability based on a Spatial Light Modulator will also be added to the system to improve beam pointing accuracy.

4 Gbps direct modulation of 450 nm GaN laser for high-speed visible light communication.

PubMed

Lee, Changmin; Zhang, Chong; Cantore, Michael; Farrell, Robert M; Oh, Sang Ho; Margalith, Tal; Speck, James S; Nakamura, Shuji; Bowers, John E; DenBaars, Steven P

2015-06-15

We demonstrate high-speed data transmission with a commercial high power GaN laser diode at 450 nm. 2.6 GHz bandwidth was achieved at an injection current of 500 mA using a high-speed visible light communication setup. Record high 4 Gbps free-space data transmission rate was achieved at room temperature.

Integrated Approach to Airborne Laser Communication

DTIC Science & Technology

2008-12-01

deformable mirror [66, 69, 80]. Some researchers have proposed complicated wavefront control systems to sense and correct the transmitted signals in real...Sensors at the imaging system or laser transmitter measure how the turbulence affects the beacon. If the differences between the phase effects ( wavefront ...communications are severely affected by clouds, dust, and atmospheric turbulence , causing deep, long fades at the receiver. Ultimately a hybrid

Laser cutting system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dougherty, Thomas J

A workpiece cutting apparatus includes a laser source, a first suction system, and a first finger configured to guide a workpiece as it moves past the laser source. The first finger includes a first end provided adjacent a point where a laser from the laser source cuts the workpiece, and the first end of the first finger includes an aperture in fluid communication with the first suction system.

Method and system for communicating with a laser power driver

DOEpatents

Telford, Steven

2017-07-18

A system for controlling a plurality of laser diodes includes an optical transmitter coupled to the laser diode driver for each laser diode. An optical signal including bi-phase encoded data is provided to each laser diode driver. The optical signal includes current level and pulse duration information at which each of the diodes is to be driven. Upon receiving a trigger signal, the laser diode drivers operate the laser diodes using the current level and pulse duration information to output a laser beam.

A multi-rate DPSK modem for free-space laser communications

NASA Astrophysics Data System (ADS)

Spellmeyer, N. W.; Browne, C. A.; Caplan, D. O.; Carney, J. J.; Chavez, M. L.; Fletcher, A. S.; Fitzgerald, J. J.; Kaminsky, R. D.; Lund, G.; Hamilton, S. A.; Magliocco, R. J.; Mikulina, O. V.; Murphy, R. J.; Rao, H. G.; Scheinbart, M. S.; Seaver, M. M.; Wang, J. P.

2014-03-01

The multi-rate DPSK format, which enables efficient free-space laser communications over a wide range of data rates, is finding applications in NASA's Laser Communications Relay Demonstration. We discuss the design and testing of an efficient and robust multi-rate DPSK modem, including aspects of the electrical, mechanical, thermal, and optical design. The modem includes an optically preamplified receiver, an 0.5-W average power transmitter, a LEON3 rad-hard microcontroller that provides the command and telemetry interface and supervisory control, and a Xilinx Virtex-5 radhard reprogrammable FPGA that both supports the high-speed data flow to and from the modem and controls the modem's analog and digital subsystems. For additional flexibility, the transmitter and receiver can be configured to support operation with multi-rate PPM waveforms.

5.625 Gbps bidirectional laser communications measurements between the NFIRE satellite and an optical ground station

NASA Astrophysics Data System (ADS)

Fields, Renny A.; Kozlowski, David A.; Yura, Harold T.; Wong, Robert L.; Wicker, Josef M.; Lunde, Carl T.; Gregory, Mark; Wandernoth, Bernhard K.; Heine, Frank F.; Luna, Joseph J.

2011-11-01

5.625 Gbps bidirectional laser communication at 1064 nm has been demonstrated on a repeatable basis between a Tesat coherent laser communication terminal with a 6.5 cm diameter ground aperture mounted inside the European Space Agency Optical Ground Station dome at Izana, Tenerife and a similar space-based terminal (12.4 cm diameter aperture) on the Near-Field InfraRed Experiment (NFIRE) low-earth-orbiting spacecraft. Both night and day bidirectional links were demonstrated with the longest being 177 seconds in duration. Correlation with atmospheric models and preliminary atmospheric r0 and scintillation measurements have been made for the conditions tested, suggesting that such coherent systems can be deployed successfully at still lower altitudes without resorting to the use of adaptive optics for compensation.

Influence of laser linewidth and polarization modulator length on polarization shift keying for free space optical communication.

PubMed

Han, Biao; Zhao, Wei; Xie, Xiaoping; Su, Yulong; Wang, Wei; Hu, Hui

2015-04-06

Modulating signal with polarization modulator (PolM) is the simplest method for polarization shift keying (PolSK) in free space optical communication. However, this method has an intrinsic drawback on degree of polarization (DOP) reduction for the existence of polarization mode dispersion (PMD) in PolM. In this work, we analyze this change of DOP and its influence on PolSK using coherency matrix. We demonstrate that the decrease of DOP after PolM will generate extra loss and bit error ratio (BER) for PolSK communication, while this loss and BER will aggravate with the increase of laser linewidth and PolM length. For a practical PolSK system, laser linewidth should be less than 0.008nm.

A Post-Processing Receiver for the Lunar Laser Communications Demonstration Project

NASA Technical Reports Server (NTRS)

Srinivasan, Meera; Birnbaum, Kevin; Cheng, Michael; Quirk, Kevin

2013-01-01

The Lunar Laser Communications Demonstration Project undertaken by MIT Lincoln Laboratory and NASA's Goddard Space Flight Center will demonstrate high-rate laser communications from lunar orbit to the Earth. NASA's Jet Propulsion Laboratory is developing a backup ground station supporting a data rate of 39 Mbps that is based on a non-real-time software post-processing receiver architecture. This approach entails processing sample-rate-limited data without feedback in the presence high uncertainty in downlink clock characteristics under low signal flux conditions. In this paper we present a receiver concept that addresses these challenges with descriptions of the photodetector assembly, sample acquisition and recording platform, and signal processing approach. End-to-end coded simulation and laboratory data analysis results are presented that validate the receiver conceptual design.

Intensity position modulation for free-space laser communication system

NASA Astrophysics Data System (ADS)

Jangjoo, Alireza; Faghihi, F.

2004-12-01

In this research a novel modulation technique for free-space laser communication system called Intensity Position Modulation (IPM) is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of linear part on the reverse biased pn photodiode produced alternating currents which contain the information. Here, no characteristic property of the beam as intensity or frequency is changed and only the beam position moves laterally. We demonstrated that in this method no bandwidth is required, so it is possible to reduce the background radiation noise by narrowband filtering of the carrier. The fidelity of the analog voice communication system which is made upon the IPM is satisfactory and we are able to transmit the audio signals up to 1Km.

New coherent laser communication detection scheme based on channel-switching method.

PubMed

Liu, Fuchuan; Sun, Jianfeng; Ma, Xiaoping; Hou, Peipei; Cai, Guangyu; Sun, Zhiwei; Lu, Zhiyong; Liu, Liren

2015-04-01

A new coherent laser communication detection scheme based on the channel-switching method is proposed. The detection front end of this scheme comprises a 90° optical hybrid and two balanced photodetectors which outputs the in-phase (I) channel and quadrature-phase (Q) channel signal current, respectively. With this method, the ultrahigh speed analog/digital transform of the signal of the I or Q channel is not required. The phase error between the signal and local lasers is obtained by simple analog circuit. Using the phase error signal, the signals of the I/Q channel are switched alternately. The principle of this detection scheme is presented. Moreover, the comparison of the sensitivity of this scheme with that of homodyne detection with an optical phase-locked loop is discussed. An experimental setup was constructed to verify the proposed detection scheme. The offline processing procedure and results are presented. This scheme could be realized through simple structure and has potential applications in cost-effective high-speed laser communication.

Demonstration of a free-space optical communication system using a solar-pumped laser as signal transmitter

NASA Astrophysics Data System (ADS)

Guan, Z.; Zhao, C. M.; Yang, S. H.; Wang, Y.; Ke, J. Y.; Zhang, H. Y.

2017-05-01

A free-space optical communication system with a sun light directly pumped laser as the signal transmitter was demonstrated. A 0.6  ×  0.6 m Fresnel lens was used as the primary concentrator to collect the solar light. 6.8 W continuous wave laser power was obtained from a 4 mm diameter grooved Nd:YAG rod. The output intensity was modulated with a video signal via a LiNbO3 Mach-Zehnder optoelectronic modulator. The video signal with a resolution of 1920  *  1080/frame and the frame rate of 25 Hz was transmitted over five-meter free-space in real time with high fidelity. The transmission rate was 125 Mbps and bit error rate was lower than 10-6. This research shows the feasibility of applying a solar light directly pumped laser for free-space optical communication, which is significant for telecommunications between satellites.

Reduction of ETS-VI Laser Communication Equipment Optical-Downlink Telemetry Collected During GOLD

NASA Technical Reports Server (NTRS)

Toyoshima, M.; Araki, K.; Arimoto, Y.; Toyoda, M.; Jeganathan, M.; Wilson, K.; Lesh, J. R.

1997-01-01

Free-space laser communications experiments were conducted between the laser communication equipment (LCE) on board the Japanese Engineering Test Satellite VI (ETS-VI) and the ground station located at the Table Mountain Facility (TMF) during late 1995 and early 1996. This article describes the on-line data reduction process used to decode LCE telemetry (called E2) downlinked on the optical carrier during the Ground/Orbiter Lasercomm Demonstration (GOLD) experiments. The LCE has the capability of transmitting real-time sensor and status information at 128 kbps by modulating the onboard diode laser. The optical downlink was detected on the ground, bit synchronized, and the resulting data stream stored on a data recorder. The recorded data were subsequently decoded by on-line data processing that included cross-correlation of the known telemetry data format and the downlink data stream. Signals obtained from the processing can be useful not only in evaluating the characteristics of the LCE but also in understanding uplink and downlink signal quality.

A unique multi-access laser communications transceiver system

NASA Technical Reports Server (NTRS)

Ross, Monte

1990-01-01

A 'many points in one point' multiaccess laser system has been examined, and results are reported which indicating the feasibility of optical communications multiaccess communications is feasible and that the resultant terminal size and with savings are very substantial compared to the dedicated optical terminals or RF multiaccess approaches. A preliminary design has been accomplished of a package that can weigh less than 150 pounds and which uses a 10-in. effective diameter fixed telescope and requires less than 100 W of regulated power and less than 8 cu ft of space.

Fine pointing control for free-space optical communication

NASA Technical Reports Server (NTRS)

Portillo, A. A.; Ortiz, G. G.; Racho, C.

2000-01-01

Free-Space Optical Communications requires precise, stable laser pointing to maintain operating conditions. This paper also describes the software and hardware implementation of Fine Pointing Control based on the Optical Communications Demonstrator architecture.

Directly Phase-Modulated Light Source

NASA Astrophysics Data System (ADS)

Yuan, Z. L.; Fröhlich, B.; Lucamarini, M.; Roberts, G. L.; Dynes, J. F.; Shields, A. J.

2016-07-01

The art of imparting information onto a light wave by optical signal modulation is fundamental to all forms of optical communication. Among many schemes, direct modulation of laser diodes stands out as a simple, robust, and cost-effective method. However, the simultaneous changes in intensity, frequency, and phase have prevented its application in the field of secure quantum communication. Here, we propose and experimentally demonstrate a directly phase-modulated light source which overcomes the main disadvantages associated with direct modulation and is suitable for diverse applications such as coherent communications and quantum cryptography. The source separates the tasks of phase preparation and pulse generation between a pair of semiconductor lasers leading to very pure phase states. Moreover, the cavity-enhanced electro-optic effect enables the first example of subvolt half-wave phase modulation at high signal rates. The source is compact, stable, and versatile, and we show its potential to become the standard transmitter for future quantum communication networks based on attenuated laser pulses.

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 part of my PhD work. The design tool created for the research of the fly eye is then used to study different applications that may be implemented with the concept. Research is done on the mathematical feasibility, modeling, design, application of the technology, and its characterization in a simulation environment. In addition, effects of atmospheric turbulence on beam propagation in free space, and applying data security using optical encryption are also researched.

Towards Laser Cooling Trapped Ions with Telecom Light

NASA Astrophysics Data System (ADS)

Dungan, Kristina; Becker, Patrick; Donoghue, Liz; Liu, Jackie; Olmschenk, Steven

2015-05-01

Quantum information has many potential applications in communication, atomic clocks, and the precision measurement of fundamental constants. Trapped ions are excellent candidates for applications in quantum information because of their isolation from external perturbations, and the precise control afforded by laser cooling and manipulation of the quantum state. For many applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress towards laser cooling and trapping of doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Additionally, we present progress on optimization of a second-harmonic generation cavity for laser cooling and trapping barium ions, for future sympathetic cooling experiments. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

SU-E-T-99: Design and Development of Isocenter Parameter System for CT Simulation Laser Based On DICOM RT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, G

2014-06-01

Purpose: In order to receive DICOM files from treatment planning system and generate patient isocenter positioning parameter file for CT laser system automatically, this paper presents a method for communication with treatment planning system and calculation of isocenter parameter for each radiation field. Methods: Coordinate transformation and laser positioning file formats were analyzed, isocenter parameter was calculated via data from DICOM CT Data and DICOM RTPLAN file. An in-house software-DicomGenie was developed based on the object-oriented program platform-Qt with DCMTK SDK (Germany OFFIS company DICOM SDK) . DicomGenie was tested for accuracy using Philips CT simulation plan system (Tumor LOC,more » Philips) and A2J CT positioning laser system (Thorigny Sur Marne, France). Results: DicomGenie successfully established DICOM communication between treatment planning system, DICOM files were received by DicomGenie and patient laser isocenter information was generated accurately. Patient laser parameter data files can be used for for CT laser system directly. Conclusion: In-house software DicomGenie received and extracted DICOM data, isocenter laser positioning data files were created by DicomGenie and can be use for A2J laser positioning system.« less

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.

Overview and Status of the Lunar Laser Communication Demonstration

NASA Technical Reports Server (NTRS)

Boroson, D. M.; Robinson, B. S.; Burianek, D. A.; Murphy, D. V.; Biswas, A.

2012-01-01

The Lunar Laser Communication Demonstration (LLCD), a project being undertaken by MIT Lincoln Laboratory, NASA's Goddard Space Flight Center, and the Jet Propulsion Laboratory, will be NASA's first attempt to demonstrate optical communications between a lunar orbiting spacecraft and Earth-based ground receivers. The LLCD space terminal will be flown on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft, presently scheduled to launch in 2013. LLCD will demonstrate downlink optical communications at rates up to 620 Mbps, uplink optical communications at rates up to 20 Mbps, and two-way time-of-flight measurements with the potential to perform ranging with sub-centimeter accuracy. We describe the objectives of the LLCD program, key technologies employed in the space and ground terminals, and show the status of development of the several systems.

InP on SOI devices for optical communication and optical network on chip

NASA Astrophysics Data System (ADS)

Fedeli, J.-M.; Ben Bakir, B.; Olivier, N.; Grosse, Ph.; Grenouillet, L.; Augendre, E.; Phillippe, P.; Gilbert, K.; Bordel, D.; Harduin, J.

2011-01-01

For about ten years, we have been developing InP on Si devices under different projects focusing first on μlasers then on semicompact lasers. For aiming the integration on a CMOS circuit and for thermal issue, we relied on SiO2 direct bonding of InP unpatterned materials. After the chemical removal of the InP substrate, the heterostructures lie on top of silicon waveguides of an SOI wafer with a separation of about 100nm. Different lasers or photodetectors have been achieved for off-chip optical communication and for intra-chip optical communication within an optical network. For high performance computing with high speed communication between cores, we developed InP microdisk lasers that are coupled to silicon waveguide and produced 100μW of optical power and that can be directly modulated up to 5G at different wavelengths. The optical network is based on wavelength selective circuits with ring resonators. InGaAs photodetectors are evanescently coupled to the silicon waveguide with an efficiency of 0.8A/W. The fabrication has been demonstrated at 200mm wafer scale in a microelectronics clean room for CMOS compatibility. For off-chip communication, silicon on InP evanescent laser have been realized with an innovative design where the cavity is defined in silicon and the gain localized in the QW of bonded InP hererostructure. The investigated devices operate at continuous wave regime with room temperature threshold current below 100 mA, the side mode suppression ratio is as high as 20dB, and the fibercoupled output power is {7mW. Direct modulation can be achieved with already 6G operation.

Method of high speed flow field influence and restrain on laser communication

NASA Astrophysics Data System (ADS)

Meng, Li-xin; Wang, Chun-hui; Qian, Cun-zhu; Wang, Shuo; Zhang, Li-zhong

2013-08-01

For laser communication performance which carried by airplane or airship, due to high-speed platform movement, the air has two influences in platform and laser communication terminal window. The first influence is that aerodynamic effect causes the deformation of the optical window; the second one is that a shock wave and boundary layer would be generated. For subsonic within the aircraft, the boundary layer is the main influence. The presence of a boundary layer could change the air density and the temperature of the optical window, which causes the light deflection and received beam spot flicker. Ultimately, the energy hunting of the beam spot which reaches receiving side increases, so that the error rate increases. In this paper, aerodynamic theory is used in analyzing the influence of the optical window deformation due to high speed air. Aero-optics theory is used to analyze the influence of the boundary layer in laser communication link. Based on this, we focused on working on exploring in aerodynamic and aero-optical effect suppression method in the perspective of the optical window design. Based on planning experimental aircraft types and equipment installation location, we optimized the design parameters of the shape and thickness of the optical window, the shape and size of air-management kit. Finally, deformation of the optical window and air flow distribution were simulated by fluid simulation software in the different mach and different altitude fly condition. The simulation results showed that the optical window can inhibit the aerodynamic influence after optimization. In addition, the boundary layer is smoothed; the turbulence influence is reduced, which meets the requirements of the airborne laser communication.

Space-Based Optical Communications with CubeSats

NASA Technical Reports Server (NTRS)

Ebert, Monica L.; Nguyen, Anh Ngoc; Frost, Chad

2017-01-01

Optical communication systems use lasers to encode and transmit data with higher speed and density than traditional radio frequency (RF)-based communications. Smaller antennas, lower power requirements, and increased spectrum availability enable optical communications to be integrated into CubeSats more easily than radios, enabling afford-able communications solutions for future NASA missions.

Close-form expression of one-tap normalized LMS carrier phase recovery in optical communication systems

NASA Astrophysics Data System (ADS)

Xu, Tianhua; Jacobsen, Gunnar; Popov, Sergei; Li, Jie; Liu, Tiegen; Zhang, Yimo

2016-10-01

The performance of long-haul high speed coherent optical fiber communication systems is significantly degraded by the laser phase noise and the equalization enhanced phase noise (EEPN). In this paper, the analysis of the one-tap normalized least-mean-square (LMS) carrier phase recovery (CPR) is carried out and the close-form expression is investigated for quadrature phase shift keying (QPSK) coherent optical fiber communication systems, in compensating both laser phase noise and equalization enhanced phase noise. Numerical simulations have also been implemented to verify the theoretical analysis. It is found that the one-tap normalized least-mean-square algorithm gives the same analytical expression for predicting CPR bit-error-rate (BER) floors as the traditional differential carrier phase recovery, when both the laser phase noise and the equalization enhanced phase noise are taken into account.

A new imaging technique for detecting interstellar communications

NASA Astrophysics Data System (ADS)

Vallerga, John; Welsh, Barry; Kotze, Marissa; Siegmund, Oswald

2017-01-01

We report on a unique detection methodology using the Berkeley Visible Image Tube (BVIT) mounted on the 10m Southern African Large Telescope (SALT) to search for laser pulses originating in communications from advanced extraterrestrial (ET) civilizations residing on nearby Earth-like planets located within their habitability zones. The detection technique assumes that ET communicates through high powered pulsed lasers with pulse durations on the order of 5 nanoseconds, the signals thereby being brighter than that of the host star within this very short period of time. Our technique turns down the gain of the optically sensitive photon counting microchannel plate detector such that ~30 photons are required in a 5ns window to generate an imaged event. Picking a priori targets with planets in the habitable zone substantially reduces the false alarm rate. Interplanetary communication by optical masers was first postulated by Schwartz and Townes in 1961. Under the assumption that ET has access to a 10 m class telescope operated as a transmitter then we could detect lasers with a similar power to that of the Livermore Laboratory laser (~1.8Mj per pulse), to a distance of ~ 1000 pc. In this talk we present the results of 2400 seconds of BVIT observations on the SALT of the star Wolf 1061, which is known to harbor an Earth-sized exoplanet located in the habitability zone. At this distance (4.3 pc), BVIT on SALT could detect a 48 joule per pulse laser, now commercially available as tabletop devices.

The use of integrated focal plane array technologies in laser microsatellite networks

NASA Astrophysics Data System (ADS)

Arnon, Shlomi

2004-10-01

Clustering micro satellites in cooperative fly formation constellations leads to high-performance space systems. The only way to achieve high-speed communication between the satellites is by a laser beam with a narrow divergence angle. In order to make the communication successful three types of focal plane detector arrays are required in the communication terminal: acquisition, tracking and communication detector arrays. The acquisition detector array is used to acquire the neighbor satellite using a wide field-of-view telescope. The tracking detector provides fast, real time and accurate direction location of the neighbor satellite. Based on the information from the acquisition and tracking detectors the receiver and transmitter maintain line of sight. The development of large, fast and very sensitive focal plane detector arrays makes it possible to implement the acquisition, tracking and communication with only one focal plane detector array. By doing so it is possible to reduce dramatically the size, weight, and cost of the optics and electronics which leads to lightweight communication terminals. As a result, the satellites are smaller and lighter, which reduces the space mission cost and increases the booster efficiency. In this paper we will present an overview of the concept of integrated focal plane arrays for laser satellite communication. We also present simulation results based on real system parameters and compare different implementation options.

Qualification testing of fiber-based laser transmitters and on-orbit validation of a commercial laser system

NASA Astrophysics Data System (ADS)

Wright, M. W.; Wilkerson, M. W.; Tang, R. R.

2017-11-01

Qualification testing of fiber based laser transmitters is required for NASA's Deep Space Optical Communications program to mature the technology for space applications. In the absence of fully space qualified systems, commercial systems have been investigated in order to demonstrate the robustness of the technology. To this end, a 2.5 W fiber based laser source was developed as the transmitter for an optical communications experiment flown aboard the ISS as a part of a technology demonstration mission. The low cost system leveraged Mil Standard design principles and Telcordia certified components to the extent possible and was operated in a pressure vessel with active cooling. The laser was capable of high rate modulation but was limited by the mission requirements to 50 Mbps for downlinking stored video from the OPALS payload, externally mounted on the ISS. Environmental testing and space qualification of this unit will be discussed along with plans for a fully space qualified laser transmitter.

Laser-Based Acousto-Optic Uplink Communications Technique

DTIC Science & Technology

2003-08-18

An apparatus for enabling acousto - optic communication comprising an in-water platform comprising means for emitting an acoustic signal to an acousto ...portion of the first interrogation beam and a second laser beam formed from the reflection of the first interrogation beam off of the acousto - optic interaction... optic interaction zone, an in-air platform comprising the ability for transmitting a first optical interrogation beam, the ability for receiving a

Link establishment criterion and topology optimization for hybrid GPS satellite communications with laser crosslinks

NASA Astrophysics Data System (ADS)

Li, Lun; Wei, Sixiao; Tian, Xin; Hsieh, Li-Tse; Chen, Zhijiang; Pham, Khanh; Lyke, James; Chen, Genshe

2018-05-01

In the current global positioning system (GPS), the reliability of information transmissions can be enhanced with the aid of inter-satellite links (ISLs) or crosslinks between satellites. Instead of only using conventional radio frequency (RF) crosslinks, the laser crosslinks provide an option to significantly increase the data throughput. The connectivity and robustness of ISL are needed for analysis, especially for GPS constellations with laser crosslinks. In this paper, we first propose a hybrid GPS communication architecture in which uplinks and downlinks are established via RF signals and crosslinks are established via laser links. Then, we design an optical crosslink assignment criteria considering the practical optical communication factors such as optical line- of-sight (LOS) range, link distance, and angular velocity, etc. After that, to further improve the rationality of establishing crosslinks, a topology control algorithm is formulated to optimize GPS crosslink networks at both physical and network layers. The RF transmission features for uplink and downlink and optical transmission features for crosslinks are taken into account as constraints for the optimization problem. Finally, the proposed link establishment criteria are implemented for GPS communication with optical crosslinks. The designs of this paper provide a potential crosslink establishment and topology control algorithm for the next generation GPS.

Development of Laser Beam Transmission Strategies for Future Ground-to-Space Optical Communications

NASA Technical Reports Server (NTRS)

Wilson, Keith E.; Kovalik, Joseph M.; Biswas, Abhijit; Roberts, William T.

2007-01-01

Optical communications is a key technology to meet the bandwidth expansion required in the global information grid. High bandwidth bi-directional links between sub-orbital platforms and ground and space terminals can provide a seamless interconnectivity for rapid return of critical data to analysts. The JPL Optical Communications Telescope Laboratory (OCTL) is located in Wrightwood California at an altitude of 2.2.km. This 200 sq-m facility houses a state-of- the-art 1-m telescope and is used to develop operational strategies for ground-to-space laser beam propagation that include safe beam transmission through navigable air space, adaptive optics correction and multi-beam scintillation mitigation, and line of sight optical attenuation monitoring. JPL has received authorization from international satellite owners to transmit laser beams to more than twenty retro-reflecting satellites. This paper presents recent progress in the development of these operational strategies tested by narrow laser beam transmissions from the OCTL to retro-reflecting satellites. We present experimental results and compare our measurements with predicted performance for a variety of atmospheric conditions.

Integration and test of high-speed transmitter electronics for free-space laser communications

NASA Technical Reports Server (NTRS)

Soni, Nitin J.; Lizanich, Paul J.

1994-01-01

The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wasner, Evan; Bearden, Sean; Žutić, Igor, E-mail: zigor@buffalo.edu

Digital operation of lasers with injected spin-polarized carriers provides an improved operation over their conventional counterparts with spin-unpolarized carriers. Such spin-lasers can attain much higher bit rates, crucial for optical communication systems. The overall quality of a digital signal in these two types of lasers is compared using eye diagrams and quantified by improved Q-factors and bit-error-rates in spin-lasers. Surprisingly, an optimal performance of spin-lasers requires finite, not infinite, spin-relaxation times, giving a guidance for the design of future spin-lasers.

Design of a solar-pumped frequency-doubled 532 nm Nd:YVO4 laser

NASA Astrophysics Data System (ADS)

Kittiboonanan, P.; Putchana, W.; Deeudomand, M.; Ratanavis, A.

2017-09-01

During the last year we have made progresson a development of a frequency-doubled 532 nm Nd:YVO4 laser pumped by solar light. The research aimed to demonstrate solar pumped lasers consisting of the optically contracted Nd:YVO4 crystal and KTP crystal with a system of laser mirrors deposited onto crystal sides. The Cassegrain reflector is used as the configuration. This solar pumped laser system is appealing for a variety applications including laser communication, imaging and defense applications.

Design, fabrication, and optimization of quantum cascade laser cavities and spectroscopy of the intersubband gain

NASA Astrophysics Data System (ADS)

Dirisu, Afusat Olayinka

Quantum Cascade (QC) lasers are intersubband light sources operating in the wavelength range of ˜ 3 to 300 mum and are used in applications such as sensing (environmental, biological, and hazardous chemical), infrared countermeasures, and free-space infrared communications. The mid-infrared range (i.e. lambda ˜ 3-30 mum) is of particular importance in sensing because of the strong interaction of laser radiation with various chemical species, while in free space communications the atmospheric windows of 3-5 mum and 8-12 mum are highly desirable for low loss transmission. Some of the requirements of these applications include, (1) high output power for improved sensitivity; (2) high operating temperatures for compact and cost-effective systems; (3) wide tunability; (4) single mode operation for high selectivity. In the past, available mid-infrared sources, such as the lead-salt and solid-state lasers, were bulky, expensive, or emit low output power. In recent years, QC lasers have been explored as cost-effective and compact sources because of their potential to satisfy and exceed all the above requirements. Also, the ultrafast carrier lifetimes of intersubband transitions in QC lasers are promising for high bandwidth free-space infrared communication. This thesis was focused on the improvement of QC lasers through the design and optimization of the laser cavity and characterization of the laser gain medium. The optimization of the laser cavity included, (1) the design and fabrication of high reflection Bragg gratings and subwavelength antireflection gratings, by focused ion beam milling, to achieve tunable, single mode and high power QC lasers, and (2) modeling of slab-coupled optical waveguide QC lasers for high brightness output beams. The characterization of the QC laser gain medium was carried out using the single-pass transmission experiment, a sensitive measurement technique, for probing the intersubband transitions and the electron distribution of QC lasers under different temperatures and applied bias conditions, unlike typical infrared measurement techniques that are restricted to non-functional devices. With the single-pass technique, basic understanding of the physics behind the workings of the QC laser gain can be achieved, which is invaluable in the design of QC lasers with high output power and high operating temperatures.

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.

Using the combination refraction-reflection solid to design omni-directional light source used in underwater wireless optical communication

NASA Astrophysics Data System (ADS)

Rao, Jionghui; Yao, Wenming; Wen, Linqiang

2015-10-01

Underwater wireless optical communication is a communication technology which uses laser as an information carrier and transmits data through water. Underwater wireless optical communication has some good features such as broader bandwidth, high transmission rate, better security, anti—interference performance. Therefore, it is promising to be widely used in the civil and military communication domains. It is also suitable for high-speed, short-range communication between underwater mobile vehicles. This paper presents a design approach of omni-directional light source used in underwater wireless optical communication, using TRACEPRO simulation tool to help design a combination solid composed of the lens, conical reflector and parabolic reflector, and using the modulated DPSS green laser in the transmitter module to output the laser beam in small divergence angles, after expanded by the combination refraction-reflection solid, the angle turns into a space divergence angle of 2π, achieving the omni-directional light source of hemisphere space, and test in the air and underwater, the result shows that the effect is fine. This paper analyzes the experimental test in the air and water, in order to make further improvement of the uniformity of light distribution, we optimize the reflector surface parameters of combination refraction-reflection solid and test in the air and water. The result shows that omni-directional light source used in underwater wireless optical communication optimized could achieve the uniformity of light distribution of underwater space divergence angle of 2π. Omni-directional light source used in underwater wireless optical communication designed in this paper has the characteristics of small size and uniformity of light distribution, it is suitable for application between UUVs, AUVs, Swimmer Delivery Vehicles (SDVs) and other underwater vehicle fleet, it realizes point-to-multipoint communications.

Experimental demonstration of an optical phased array antenna for laser space communications.

PubMed

Neubert, W M; Kudielka, K H; Leeb, W R; Scholtz, A L

1994-06-20

The feasibility of an optical phased array antenna applicable for spaceborne laser communications was experimentally demonstrated. Heterodyne optical phase-locked loops provide for a defined phase relationship between the collimated output beams of three single-mode fibers. In the far field the beams interfere with a measured efficiency of 99%. The main lobe of the interference pattern can be moved by phase shifting the subaperture output beams. The setup permitted agile beam steering within an angular range of 1 mr and a response time of 0.7 ms. We propose an operational optical phased array antenna fed by seven lasers, featuring high transmit power and redundance.

Fiber-coupling efficiency for free-space optical communication through atmospheric turbulence.

PubMed

Dikmelik, Yamaç; Davidson, Frederic M

2005-08-10

High-speed free-space optical communication systems have recently used fiber-optic components. The received laser beam in such a system must be coupled into a single-mode fiber at the input of the receiver module. However, propagation through atmospheric turbulence degrades the spatial coherence of a laser beam and limits the fiber-coupling efficiency. We numerically evaluate the fiber-coupling efficiency for laser light distorted by atmospheric turbulence. We also investigate the use of a coherent fiber array as a receiver structure and find that a coherent fiber array that consists of seven subapertures would significantly increase the fiber-coupling efficiency.

Low threshold CW Nc laser oscillator at 1060 nm study

NASA Technical Reports Server (NTRS)

Birnbaum, M.; Deshazer, L. G.

1976-01-01

A broad range of characteristics of neodymium/yag lasers were investigated. With Nd:YVO4 crystals, CW 1.06 mu lasers were operated with thresholds a factor of 2 lower than Nd:YAG and with greater slope efficiencies. Thus, the first step in the development of new oscillators suitable for application in high data rate laser communication systems which surpass the present performance of the Nd:YAG laser has been successfully demonstrated.

Cr-doped scandium borate laser

DOEpatents

Chai, Bruce H.; Lai, Shui T.; Long, Margaret N.

1989-01-01

A broadly wavelength-tunable laser is provided which comprises as the laser medium a single crystal of MBO.sub.3 :Cr.sup.3+, where M is selected from the group of Sc, In and Lu. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photochemistry, etc.

A Simple Laser Microphone for Classroom Demonstration

ERIC Educational Resources Information Center

Moses, James M.; Trout, K. P.

2006-01-01

Communication through the modulation of electromagnetic radiation has become a foundational technique in modern technology. In this paper we discuss a modern day method of eavesdropping based upon the modulation of laser light reflected from a window pane. A simple and affordable classroom demonstration of a "laser microphone" is…

Learning about Lasers

ERIC Educational Resources Information Center

Roberts, Larry

2011-01-01

The word laser is an acronym. It stands for Light Amplification by Stimulated Emission of Radiation. Lasers, invented in 1958, are used to cut and fuse materials, accurately survey long distances, communicate across fiber-optic phone lines, produce 3D pictures, make special effects, help navigation, and read bar codes for cash registers. A laser…

Information Technologies for the 1980's: Lasers and Microprocessors.

ERIC Educational Resources Information Center

Mathews, William D.

This discussion of the development and application of lasers and microprocessors to information processing stresses laser communication in relation to capacity, reliability, and cost and the advantages of this technology to real-time information access and information storage. The increased capabilities of microprocessors are reviewed, and a…

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.

Fully integrated multi-optoelectronic synthesizer for THz pumping source in wireless communications with rich backup redundancy and wide tuning range.

PubMed

Xu, Junjie; Hou, Lianping; Deng, Qiufang; Han, Liangshun; Liang, Song; Marsh, John H; Zhu, Hongliang

2016-07-06

We report a monolithic photonic integrated circuit (PIC) for THz communication applications. The PIC generates up to 4 optical frequency lines which can be mixed in a separate device to generate THz radiation, and each of the optical lines can be modulated individually to encode data. Physically, the PIC comprises an array of wavelength tunable distributed feedback lasers each with its own electro-absorption modulator. The lasers are designed with a long cavity to operate with a narrow linewidth, typically <4 MHz. The light from the lasers is coupled via an multimode interference (MMI) coupler into a semiconductor optical amplifier (SOA). By appropriate selection and biasing of pairs of lasers, the optical beat signal can be tuned continuously over the range from 0.254 THz to 2.723 THz. The EAM of each channel enables signal leveling balanced between the lasers and realizing data encoding, currently at data rates up to 6.5 Gb/s. The PIC is fabricated using regrowth-free techniques, making it economic for volume applications, such for use in data centers. The PIC also has a degree of redundancy, making it suitable for applications, such as inter-satellite communications, where high reliability is mandatory.

Design of 2*6 optical hybrid in inter-satellite coherent laser communications

NASA Astrophysics Data System (ADS)

Xu, Nan; Liu, Liren; Liu, De'an; Wan, Lingyu; Zhou, Yu

2008-08-01

Compared with direct detection, homodyne binary phase shift keying receivers can achieve the best sensitivity theoretically, and became the trend of the research and application in inter-satellite coherent laser communications. In coherent optical communication systems an optical hybrid is an essential component of the receiver. It demodulates the incoming signal by mixing it with the local oscillator. We present a design of a 2*6 optical hybrid. 4 output ports of the hybrid give the narrow mixed beams of the incoming signal and the local oscillator shifted by 90°for communication, and the others give the wide mixed beams with a shifted degree of 180°for position errors detection. CCD captures the interference pattern from the wide beams, and then the pattern is processed and analyzed by the computer. Target position information is obtained from characteristic parameter of the interference pattern. The position errors as the control signals of PAT (pointing, acquisition and tracking) subsystem drive the receiver telescope to keep tracking to the target. The application extends to coherent laser rang finder.

Fiber Laser Arrays

DTIC Science & Technology

2006-05-03

AFRL-DE-PS- AFRL-DE-PS- TR-2006-1059 TR-2006-1059 FIBER LASER ARRAYS Thomas B. Simpson L-3 Communications-Jaycor 3394...LEANNE J HENRY, Lt Col, USAF L. BRUCE SIMPSON, SES Chief, High Power Solid State Laser Branch Director, Directed Energy Directorate...SUBTITLE Fiber Laser Arrays 5c. PROGRAM ELEMENT NUMBER 62605F 5d. PROJECT NUMBER 4866 5e. TASK NUMBER LR 6. AUTHOR(S) Thomas B. Simpson

A Day in the Life of the Laser Communications Relay Demonstration Project

NASA Technical Reports Server (NTRS)

Edwards, Bernard; Israel, David; Caroglanian, Armen; Spero, James; Roberts, Tom; Moores, John

2016-01-01

This paper provides an overview of the planned concept of operations for the Laser Communications Relay Demonstration Project (LCRD), a joint project among 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). LCRD will provide at least two years of bi-directional optical communications at user data rates of up to 1.244 Gbps in an operational environment. The project lays the groundwork for establishing communications architecture and protocols, and developing the communications hardware and support infrastructure, concluding in a demonstration of optical communications' potential to meet NASA's growing need for higher data rates for future science and exploration missions. A pair of flight optical communications terminals will reside on a single commercial communications satellite in geostationary orbit; the two ground optical communications terminals will be located in Southern California and Hawaii. This paper summarizes the current LCRD architecture and key systems for the demonstration, focusing on what it will take to operate an optical communications relay that can support space-to-space, space-to-air, and space-to-ground optical links.

A Day in the Life of the Laser Communications Relay Demonstration (LCRD) Project.

NASA Technical Reports Server (NTRS)

Israel, David; Caroglanian, Armen; Edwards, Bernard; Spero, James; Roberts, Tom; Moores, John

2016-01-01

This presentation provides an overview of the planned concept of operations for the Laser Communications Relay Demonstration Project (LCRD), a joint project among NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MITLL). LCRD will provide at least two years of bi-directional optical communications at user data rates of up to 1.244 Gbps in an operational environment. The project lays the ground work for establishing communications architecture and protocols, and developing the communications hardware and support infrastructure, concluding in a demonstration of optical communications potential to meet NASAs growing need for higher data rates for future science and exploration missions. A pair of flight optical communications terminals will reside on a single commercial communications satellite in geostationary orbit; the two ground optical communications terminals will be located in Southern California and Hawaii. This paper summarizes the current LCRD architecture and key systems for the demonstration, focusing on what it will take to operate an optical communications relay that can support space-to-space, space-to-air, and space-to-ground optical links.

Methods and Devices for Space Optical Communications Using Laser Beams

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor)

2018-01-01

Light is used to communicate between objects separated by a large distance. Light beams are received in a telescopic lens assembly positioned in front of a cat's-eye lens. The light can thereby be received at various angles to be output by the cat's-eye lens to a focal plane of the cat's-eye lens, the position of the light beams upon the focal plane corresponding to the angle of the beam received. Lasers and photodetectors are distributed along this focal plane. A processor receives signals from the photodetectors, and selectively signal lasers positioned proximate the photodetectors detecting light, in order to transmit light encoding data through the cat's-eye lens and also through a telescopic lens back in the direction of the received light beams, which direction corresponds to a location upon the focal plane of the transmitting lasers.

Far field and wavefront characterization of a high-power semiconductor laser for free space optical communications

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.; Saif, Babak N.

1991-01-01

The spatial pointing angle and far field beamwidth of a high-power semiconductor laser are characterized as a function of CW power and also as a function of temperature. The time-averaged spatial pointing angle and spatial lobe width were measured under intensity-modulated conditions. The measured pointing deviations are determined to be well within the pointing requirements of the NASA Laser Communications Transceiver (LCT) program. A computer-controlled Mach-Zehnder phase-shifter interferometer is used to characterize the wavefront quality of the laser. The rms phase error over the entire pupil was measured as a function of CW output power. Time-averaged measurements of the wavefront quality are also made under intensity-modulated conditions. The measured rms phase errors are determined to be well within the wavefront quality requirements of the LCT program.

Combinatorial pulse position modulation for power-efficient free-space laser communications

NASA Technical Reports Server (NTRS)

Budinger, James M.; Vanderaar, M.; Wagner, P.; Bibyk, Steven

1993-01-01

A new modulation technique called combinatorial pulse position modulation (CPPM) is presented as a power-efficient alternative to quaternary pulse position modulation (QPPM) for direct-detection, free-space laser communications. The special case of 16C4PPM is compared to QPPM in terms of data throughput and bit error rate (BER) performance for similar laser power and pulse duty cycle requirements. The increased throughput from CPPM enables the use of forward error corrective (FEC) encoding for a net decrease in the amount of laser power required for a given data throughput compared to uncoded QPPM. A specific, practical case of coded CPPM is shown to reduce the amount of power required to transmit and receive a given data sequence by at least 4.7 dB. Hardware techniques for maximum likelihood detection and symbol timing recovery are presented.

Design the RS(255,239) encoder and interleaving in the space laser communication system

NASA Astrophysics Data System (ADS)

Lang, Yue; Tong, Shou-feng

2013-08-01

Space laser communication is researched by more and more countries. Space laser communication deserves to be researched. We can acquire higher transmission speed and better transmission quality between satellite and satellite, satellite and earth by setting up laser link. But in the space laser communication system，the reliability is under influences of many factors of atmosphere，detector noise, optical platform jitter and other factors. The intensity of the signal which is attenuated because of the long transmission distance is demanded to have higher intensity to acquire low BER. The channel code technology can enhance the anti-interference ability of the system. The theory of channel coding technology is that some redundancies is added to information codes. So it can make use of the checkout polynomial to correct errors at the sink port. It help the system to get low BER rate and coding gain. Reed-Solomon (RS) code is one of the channel code, and it is one kind of multi-ary BCH code, and it can correct both burst errors and random errors, and it is widely used in the error-control schemes. The new method of the RS encoder and interleaving based on the FPGA is proposed, aiming at satisfying the needs of the widely-used error control technology in the space laser communication field. An improved method for Finite Galois Field multiplier of encoding is proposed, and it is suitable for FPGA implementation. Comparison of the XOR gates cost between the optimization and original, the number of XOR gates is lessen more than 40% .Then give a new structure of interleaving by using the FPGA. By controlling the in-data stream and out-data stream of encoder, the asynchronous process of the whole frame is accomplished, while by using multi-level pipeline, the real-time transfer of the data is achieved. By controlling the read-address and write-address of the block RAM, the interleaving operation of the arbitrary depth is synchronously implemented. Compared with the normal method, it could reduce the complexity of the channel encoder and the hardware requirement effectively.

Laser Doppler measurement techniques for spacecraft

NASA Technical Reports Server (NTRS)

Kinman, Peter W.; Gagliardi, Robert M.

1986-01-01

Two techniques are proposed for using laser links to measure the relative radial velocity of two spacecraft. The first technique determines the relative radial velocity from a measurement of the two-way Doppler shift on a transponded radio-frequency subcarrier. The subcarrier intensity-modulates reciprocating laser beams. The second technique determines the relative radial velocity from a measurement of the two-way Doppler shift on an optical frequency carrier which is transponded between spacecraft using optical Costas loops. The first technique might be used in conjunction with noncoherent optical communications, while the second technique is compatible with coherent optical communications. The first technique simultaneously exploits the diffraction advantage of laser beams and the maturity of radio-frequency phase-locked loop technology. The second technique exploits both the diffraction advantage of laser beams and the large Doppler effect at optical frequencies. The second technique has the potential for greater accuracy; unfortunately, it is more difficult to implement since it involves optical Costas loops.

A hybrid CATV/16-QAM-OFDM visible laser light communication system

NASA Astrophysics Data System (ADS)

Lin, Chun-Yu; Li, Chung-Yi; Lu, Hai-Han; Chen, Chia-Yi; Jhang, Tai-Wei; Ruan, Sheng-Siang; Wu, Kuan-Hung

2014-10-01

A visible laser light communication (VLLC) system employing a vertical cavity surface emitting laser and spatial light modulator with hybrid CATV/16-QAM-OFDM modulating signals over a 5 m free-space link is proposed and demonstrated. With the assistance of a push-pull scheme, low-noise amplifier, and equalizer, good performances of composite second-order and composite triple beat are obtained, accompanied by an acceptable carrier-to-noise ratio performance for a CATV signal, and a low bit error rate value and clear constellation map are achieved for a 16-QAM-OFDM signal. Such a hybrid CATV/16-QAM-OFDM VLLC system would be attractive for providing services including CATV, Internet and telecommunication services.

Design and Development of Electrically Pumped Coaxial Nanoscale Laser for On-chip Optical Communication - TOPIC STIR

DTIC Science & Technology

2015-08-31

Hodaei, M. A. Miri, M. Heinrich, D. Christodoulides, M. Khajavikhan, “ PT - symmetric microring lasers ”, SPIE Photonics West San Francisco CA (2015...Broad Area PT - Symmetric Microring Lasers , CLEO: QELS_Fundamental Science. 07-JUN-15, San Jose, California. : , Hossein Hodaei, William Hayenga...Mohammad-Ali Miri, Absar Ulhassan, Demetrios N. Christodoulides, Mercedeh Khajavikhan. Tunable Parity-Time- Symmetric Microring Lasers , CLEO: Science and

Low Power Ground-Based Laser Illumination for Electric Propulsion Applications

NASA Technical Reports Server (NTRS)

Lapointe, Michael R.; Oleson, Steven R.

1994-01-01

A preliminary evaluation of low power, ground-based laser powered electric propulsion systems is presented. A review of available and near-term laser, photovoltaic, and adaptive optic systems indicates that approximately 5-kW of ground-based laser power can be delivered at an equivalent one-sun intensity to an orbit of approximately 2000 km. Laser illumination at the proper wavelength can double photovoltaic array conversion efficiencies compared to efficiencies obtained with solar illumination at the same intensity, allowing a reduction in array mass. The reduced array mass allows extra propellant to be carried with no penalty in total spacecraft mass. The extra propellant mass can extend the satellite life in orbit, allowing additional revenue to be generated. A trade study using realistic cost estimates and conservative ground station viewing capability was performed to estimate the number of communication satellites which must be illuminated to make a proliferated system of laser ground stations economically attractive. The required number of satellites is typically below that of proposed communication satellite constellations, indicating that low power ground-based laser beaming may be commercially viable. However, near-term advances in low specific mass solar arrays and high energy density batteries for LEO applications would render the ground-based laser system impracticable.

Technology forecasting for space communication. [analysis of systems for application to Spacecraft Data and Tracking Network

NASA Technical Reports Server (NTRS)

1973-01-01

A study was conducted to determine techniques for application to space communication. The subjects considered are as follows: (1) optical communication systems, (2) laser communications for data acquisition networks, (3) spacecraft data rate requirements, (4) telemetry, command, and data handling, (5) spacecraft tracking and data network antenna and preamplifier cost tradeoff study, and (6) spacecraft communication terminal evaluation.

Improvements to Optical Communication Capabilities Achieved through the Optical Injection of Semiconductor Lasers

DTIC Science & Technology

2012-03-22

locked Fabry - Perot laser showed a 57 fold improvement to the bit rate-distance product compared to the free-running case when received optical power...than 10dB for marginal changes in modulation rates. Temperature tuning of the master laser to each of the Fabry - Perot modes of the slave laser...demonstrated over 60 km of SMF in this work, shows that OIL of Fabry - Perot lasers is a viable approach towards a high-speed, long distance capable

AlGaInN laser diode technology for free-space telecom applications

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.; Watson, M. A.; Blanchard, P.; White, H.

2015-03-01

The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. We consider the suitability of AlGaInN laser diode technology for free space laser communication, both airborne links and underwater telecom applications, mainly for defense and oil and gas industries.

Remote steering of laser beams by radar- and laser-induced refractive-index gradients in the atmosphere Remote steering of laser beams

NASA Astrophysics Data System (ADS)

Zheltikov, A. M.; Shneider, M. N.; Voronin, A. A.; Sokolov, A. V.; Scully, M. O.

2012-01-01

Refractive-index gradients induced in the atmospheric air by properly tailored laser and microwave fields are shown to enable a remote steering of laser beams. Heating-assisted modulation of the refractive index of the air by microwave radiation is shown to support small-angle laser-beam bending with bending angles on the order of 10-2. Ionization of the atmospheric air by dyads of femto- and nanosecond laser pulses, on the other hand, can provide beam deflection angles in excess of π/5, offering an attractive strategy for radiation transfer, free-space communications, and laser-based standoff detection.

Lasers revisited - Their superior utility for interstellar beacons, communications, and travel

NASA Technical Reports Server (NTRS)

Rather, John D. G.

1991-01-01

This paper demonstrates reasons why research supporting SETI and Communication with Extraterrestrial Intelligence should be broadened to optical wavelengths rather than focusing almost entirely upon microwave wavelengths and technologies. New perceptions regarding the feasibility of laser technologies, along with reassessments of signal-to-noise considerations, show both the desirability and feasibility of optical interstellar transmissions, especially at IR and visible wavelengths. It is shown that utilization of the large bandwidths available at optical wavelengths greatly improves the possible use of such endeavors.

ONR Far East Scienticic Bulletin. Volume 11, Number 4, October-December 1986,

DTIC Science & Technology

1986-12-01

magnitude. Visible LEDs are used in large numbers for displays and indicator lights in consumer electronics, and infrared LEDs are used for many kinds of... infrared LDs are used, the Japanese have a large domes- tic market because the use of optical communications systems is widespread. Their devices are of...price between visible lasers used in CDs (=$10 each) and infrared lasers used for communications (=$1000 each). The big market in GaAs solar cells is

Photodiodes for ten micrometer laser communication systems

NASA Technical Reports Server (NTRS)

Cohen, S. C.

1972-01-01

The performance is discussed of 10-micron mercury-cadmiumtelluride and lead-tin-telluride photodiodes in laser heterodyne communication systems. The dependence of detector quantum efficiency, resistance, frequency response, and signal-to-noise ratio on temperature, bias, and local oscillator power are examined. Included in the discussion is an analysis of the feasibility of high temperature operation, and ability of the detector to dissipate power to a heat sink is explored. Some aspects of direct detection response are considered and figures showing flux levels from a blackbody presented.

Laser microphone

DOEpatents

Veligdan, James T.

2000-11-14

A microphone for detecting sound pressure waves includes a laser resonator having a laser gain material aligned coaxially between a pair of first and second mirrors for producing a laser beam. A reference cell is disposed between the laser material and one of the mirrors for transmitting a reference portion of the laser beam between the mirrors. A sensing cell is disposed between the laser material and one of the mirrors, and is laterally displaced from the reference cell for transmitting a signal portion of the laser beam, with the sensing cell being open for receiving the sound waves. A photodetector is disposed in optical communication with the first mirror for receiving the laser beam, and produces an acoustic signal therefrom for the sound waves.

Laser ablation system, and method of decontaminating surfaces

DOEpatents

Ferguson, Russell L.; Edelson, Martin C.; Pang, Ho-ming

1998-07-14

A laser ablation system comprising a laser head providing a laser output; a flexible fiber optic cable optically coupled to the laser output and transmitting laser light; an output optics assembly including a nozzle through which laser light passes; an exhaust tube in communication with the nozzle; and a blower generating a vacuum on the exhaust tube. A method of decontaminating a surface comprising the following steps: providing an acousto-optic, Q-switched Nd:YAG laser light ablation system having a fiber optically coupled output optics assembly; and operating the laser light ablation system to produce an irradiance greater than 1.times.10.sup.7 W/cm.sup.2, and a pulse width between 80 and 170 ns.

Higher order mode laser beam intensity fluctuations in strong oceanic turbulence

NASA Astrophysics Data System (ADS)

Baykal, Yahya

2017-05-01

Intensity fluctuations of the higher order mode laser beams are evaluated when these beams propagate in a medium exhibiting strong oceanic turbulence. Our formulation involves the modified Rytov solution that extends the Rytov solution to cover strong turbulence as well, and our recently reported expression that relates the atmospheric turbulence structure constant to the oceanic turbulence parameters and oceanic wireless optical communication link parameters. The variations of the intensity fluctuations are reported against the changes of the ratio of temperature to salinity contributions to the refractive index spectrum, rate of dissipation of kinetic energy per unit mass of fluid, rate of dissipation of mean-squared temperature, viscosity and the source size of the higher order mode laser beam. Our results indicate that under any oceanic turbulence parameters, it is advantageous to employ higher order laser modes in reducing the scintillation noise in wireless optical communication links operating in a strongly turbulent ocean.

Arenani: pointing and information query system for object beyond your reach

NASA Astrophysics Data System (ADS)

Adachi, Mariko; Sakamoto, Kunio

2008-03-01

The authors developed a prototype information query system. It is easy to get the information about an object with in your reach. But it is troublesome to do the same in case that the object is far away. If someone is around you, you can ask an easy question with a finger pointing; "What is that?" Our developed system also realizes this approach using information technologies. The system consists of a laser pointer, transmitter and receiver units for an optical communication. The laser pointer is used for pointing an object. Moreover this laser light is modulated for sending information about user's identification (ID) codes to identify who asks a question. Each object has a receiver for laser light communication and sends user's identification to a main computer. After pointing an object, a questioner receives an answer through a wireless information network like an email on the cellular phone.

Performance improvement by orthogonal pulse amplitude modulation and discrete multitone modulation signals in hybrid fiber-visible laser light communication system

NASA Astrophysics Data System (ADS)

Zhang, Fangliu; He, Jing; Deng, Rui; Chen, Qinghui; Chen, Lin

2016-10-01

A modulation format, orthogonal pulse amplitude modulation and discrete multitone modulation (O-PAM-DMT), is experimentally demonstrated in a hybrid fiber-visible laser light communication (fiber-VLLC) system using a cost-effective directly modulated laser and blue laser diode. In addition, low overhead is achieved by utilizing only one training sequence to implement synchronization and channel estimation. Through adjusting the ratio of PAM and DMT signal, three types of O-PAM-DMT signals are investigated. After transmission over a 20-km standard single-mode fiber and 5-m free-space VLLC, the receiver sensitivity for 4.36-Gbit/s O-PAM-DMT signals can be improved by 0.4, 1.4, and 2.7 dB, respectively, at a bit error rate of 1×10-3, compared with a conventional DMT signal.

Simplified Architecture for Precise Aiming of a Deep-Space Communication Laser Transceiver

NASA Technical Reports Server (NTRS)

Ortiz, Gerard G.; Farr, William H.; Charles, Jeffrey R.

2011-01-01

The simplified architecture is a minimal system for a deep-space optical communications transceiver. For a deepspace optical communications link the simplest form of the transceiver requires (1) an efficient modulated optical source, (2) a point-ahead mechanism (PAM) to compensate for two-way light travel, (3) an aperture to reduce the divergence of the transmit laser communication signal and also to collect the uplink communication signal, and (4) a receive detector to sense the uplink communication signal. Additional components are introduced to mitigate for spacecraft microvibrations and to improve the pointing accuracy. The Canonical Transceiver implements this simplified architecture (see figure). A single photon-counting smart focal plane sensor combines acquisition, tracking, and forward link data detection functionality. This improves optical efficiency by eliminating channel splits. A transmit laser blind sensor (e.g. silicon with 1,550-nm beam) provides transmit beam-pointing feedback via the two-photon absorption (TPA) process. This vastly improves the transmit/receive isolation because only the focused transmit beam is detected. A piezoelectric tiptilt actuator implements the required point-ahead angle. This point-ahead mechanism has been demonstrated to have near zero quiescent power and is flight qualified. This architecture also uses an innovative 100-mHz resonant frequency passive isolation platform to filter spacecraft vibrations with voice coil actuators for active tip-tilt correction below the resonant frequency. The canonical deep-space optical communications transceiver makes synergistic use of innovative technologies to reduce size, weight, power, and cost. This optical transceiver can be used to retire risks associated with deep-space optical communications on a planetary pathfinder mission and is complementary to ongoing lunar and access link developments.

Bit-error rate for free-space adaptive optics laser communications.

PubMed

Tyson, Robert K

2002-04-01

An analysis of adaptive optics compensation for atmospheric-turbulence-induced scintillation is presented with the figure of merit being the laser communications bit-error rate. The formulation covers weak, moderate, and strong turbulence; on-off keying; and amplitude-shift keying, over horizontal propagation paths or on a ground-to-space uplink or downlink. The theory shows that under some circumstances the bit-error rate can be improved by a few orders of magnitude with the addition of adaptive optics to compensate for the scintillation. Low-order compensation (less than 40 Zernike modes) appears to be feasible as well as beneficial for reducing the bit-error rate and increasing the throughput of the communication link.

Small Business Innovations (MISER)

NASA Technical Reports Server (NTRS)

1991-01-01

Lightwave Electronics Corporation, Mountain View, CA, developed the Series 120 and 122 non-planner diode pumped ring lasers based on a low noise ring laser with voltage tuning that they delivered to Jet Propulsion Laboratory under a Small Business Innovation Research (SBIR) contract. The voltage tuning feature allows "phase-locking" the lasers, making them "electronic," similar to radio and microwave electronic oscillators. The Series 120 and 122 can be applied to fiber sensing, coherent communications and laser radar.

RLE (Research Laboratory of Electronics) Progress Report Number 125.

DTIC Science & Technology

1983-01-01

Optical Communications 32 7.3 Picosecond Optics 35 7.4 Ultrashort Pulse Formation 37 7.5 Femtosecond Laser System 37 7.6 Parametric Scattering with...Figure 3-2: The cross section for 4 photon ionization of atomic hydrogen as calculated by 10 Reinhardt for a single frequency laser . To facilitate...profiles produced by laser intensity I* and at five times that intensity 11 510. As the laser intensity is increased, the ionization profile becomes

AlGaInN laser diode technology and systems for defence and security applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lujca; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

2015-10-01

AlGaInN laser diodes is an emerging technology for defence and security applications such as underwater communications and sensing, atomic clocks and quantum information. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries. Ridge waveguide laser diodes are fabricated to achieve single mode operation with optical powers up to 100mW with the 400-440nm wavelength range with high reliability. Visible free-space and underwater communication at frequencies up to 2.5GHz is reported using a directly modulated 422nm GaN laser diode. Low defectivity and highly uniform GaN substrates allow arrays and bars to be fabricated. High power operation operation of AlGaInN laser bars with up to 20 emitters have been demonstrated at optical powers up to 4W in a CS package with common contact configuration. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space or optical fibre system integration with a very small form-factor.

Optical Communication with Semiconductor Laser Diode. Interim Progress Report. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Davidson, Frederic; Sun, Xiaoli

1989-01-01

Theoretical and experimental performance limits of a free-space direct detection optical communication system were studied using a semiconductor laser diode as the optical transmitter and a silicon avalanche photodiode (APD) as the receiver photodetector. Optical systems using these components are under consideration as replacements for microwave satellite communication links. Optical pulse position modulation (PPM) was chosen as the signal format. An experimental system was constructed that used an aluminum gallium arsenide semiconductor laser diode as the transmitter and a silicon avalanche photodiode photodetector. The system used Q=4 PPM signaling at a source data rate of 25 megabits per second. The PPM signal format requires regeneration of PPM slot clock and word clock waveforms in the receiver. A nearly exact computational procedure was developed to compute receiver bit error rate without using the Gaussion approximation. A transition detector slot clock recovery system using a phase lock loop was developed and implemented. A novel word clock recovery system was also developed. It was found that the results of the nearly exact computational procedure agreed well with actual measurements of receiver performance. The receiver sensitivity achieved was the closest to the quantum limit yet reported for an optical communication system of this type.

Deployable wavelength optimizer for multi-laser sensing and communication undersea

NASA Astrophysics Data System (ADS)

Neuner, Burton; Hening, Alexandru; Pascoguin, B. Melvin; Dick, Brian; Miller, Martin; Tran, Nghia; Pfetsch, Michael

2017-05-01

This effort develops and tests algorithms and a user-portable optical system designed to autonomously optimize the laser communication wavelength in open and coastal oceans. In situ optical meteorology and oceanography (METOC) data gathered and analyzed as part of the auto-selection process can be stored and forwarded. The system performs closedloop optimization of three visible-band lasers within one minute by probing the water column via passive retroreflector and polarization optics, selecting the ideal wavelength, and enabling high-speed communication. Backscattered and stray light is selectively blocked by employing polarizers and wave plates, thus increasing the signal-to-noise ratio. As an advancement in instrumentation, we present autonomy software and portable hardware, and demonstrate this new system in two environments: ocean bay seawater and outdoor test pool freshwater. The next generation design is also presented. Once fully miniaturized, the optical payload and software will be ready for deployment on manned and unmanned platforms such as buoys and vehicles. Gathering timely and accurate ocean sensing data in situ will dramatically increase the knowledge base and capabilities for environmental sensing, defense, and industrial applications. Furthermore, communicating on the optimal channel increases transfer rates, propagation range, and mission length, all while reducing power consumption in undersea platforms.

TESAT laser communication terminal performance results on 5.6Gbit coherent inter satellite and satellite to ground links

NASA Astrophysics Data System (ADS)

Gregory, M.; Heine, F.; Kämpfner, H.; Meyer, R.; Fields, R.; Lunde, C.

2017-11-01

The increasing demand on high speed communication networks has stimulated the development of optical free space data transmission during the last years. TESAT has developed a laser communication terminal (LCT) that fulfills the need of a power efficient system whose capability has been successfully demonstrated at bidirectional space-to-space links and bidirectional space-to-ground links (SGLs) at a data rate of 5.625 GBit/s with a homodyne detection scheme and a BPSK modulation format. In comparison to a direct detection system, the homodyne detection scheme works as a bandpass filter. The transmission is immune to false light and even data transmission with the sun in the receiver field of view (FOV) is possible. Compared to common RF transmission which is implemented on spacecrafts for data transmission, optical transmission provides not only higher transmission rates (factor 10) but also shows excellent security features since the laser beams directivity making it immune to interception.

Solid-state lasers for coherent communication and remote sensing

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1991-01-01

Work in the stabilization of monolithic Nd:YAG lasers and the application of these lasers to nonlinear optical frequency conversion is discussed. The intrinsic stability of semiconductor diode laser pumped solid state lasers has facilitated a number of demonstration in external resonant cavity harmonic generation and stable optical parametric oscillation. Relative laser frequency stabilization of 0.3 Hz was achieved, and absolute stability of a few hundred hertz is anticipated. The challenge is now to reproduce this frequency stability in the output of tunable nonlinear optical devices. Theoretical and experimental work toward this goal are continuing.

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.

Space Optical Communications Using Laser Beams

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor)

2017-01-01

A system for communicating between an object in space and a ground station, between objects in space, or between ground stations, includes a telecentric lens. Photodetectors positioned upon a focal plane of the telecentric lens detect an inbound light beam, received from a source, that has passed through the telecentric lens to the focal plane. Lasers positioned upon the focal plane transmit light beams from the focal plane through the telecentric lens to an area that includes the source of the inbound light beam. A processor detect signals from individual photodetectors corresponding to light detected, and selectively signals individual lasers that are close to those photodetectors, resulting in a returning beam that arrives close to the source, and which carries encoded data.

Challenges of laser beam propagation near/within marine boundary layer

NASA Astrophysics Data System (ADS)

Manzur, Tariq; Katz, Richard A.; Olson, Joshua

2015-05-01

Marine atmospheric condition plays a critical role on imaging, laser beam propagation, and optical communication of the commercial and military platform. In Military platforms, ships and sailors must be able to defend and communicate with other maritime platform in sometimes volatile and hostile regions around the globe. Naval combatants need defensive and offensive capabilities against a variety of potential threats - many coming at low altitude, UAV, USV etc. High energy lasers (HELs) are currently in development, which have sufficient power levels (~100 kW) to destroy/disable most types of threats. Though target engagement and energy delivery are challenging, a HEL weapon can engage targets at the speed of light, does not require physical ammunition, and is able to run for hours at a time.

Laser space communication experiment: Modulator technology

NASA Technical Reports Server (NTRS)

Goodwin, F. E.

1973-01-01

Results are presented of a contractual program to develop the modulator technology necessary for a 10.6 micron laser communication system using cadmium telluride as the modulator material. The program consisted of the following tasks: (1) The growth of cadmium telluride crystals of sufficient size and purity and with the necessary optical properties for use as laser modulator rods. (2) Develop a low loss antireflection coating for the cadmium telluride rods. (3) Design and build a modulator capable of 300 MHz modulation. (4) Develop a modulator driver capable of a data rate of 300 MBits/sec, 12 W rms output power, and 40 percent efficiency. (5) Assemble and test the modulator system. All design goals were met and the system was built and tested.

OptoRadio: a method of wireless communication using orthogonal M-ary PSK (OMPSK) modulation

NASA Astrophysics Data System (ADS)

Gaire, Sunil Kumar; Faruque, Saleh; Ahamed, Md. Maruf

2016-09-01

Laser based radio communication system, i.e. OptoRadio, using Orthogonal M-ary PSK Modulation scheme is presented in this paper. In this scheme, when a block of data needs to be transmitted, the corresponding block of biorthogonal code is transmitted by means of multi-phase shift keying. At the receiver, two photo diodes are cross coupled. The effect is that the net output power due to ambient light is close to zero. The laser signal is then transmitted only into one of the receivers. With all other signals being cancelled out, the laser signal is an overwhelmingly dominant signal. The detailed design, bit error correction capabilities, and bandwidth efficiency are presented to illustrate the concept.

Experimental basis of laser therapy in pharynx pathology

NASA Astrophysics Data System (ADS)

Toropova, Lyudmila A.; Fedyukovich, Lyudmila V.; Egorova, Alla B.

1998-07-01

Membrane-damaging action of laser irradiation comparing with membranotoxic activity of model xenobiotics (Novocain and Acrylamide) has been evaluated in our experiments using Rosette-Forming Ability test (RFA) on rat blood lymphocytes, thymocytes, splenocytes for the assessment of membrane- mediated and receptor-mediated immune cells interactions. Infra-red laser irradiation (80 and 1500 Hz, 0.89 mkM) in vivo induced 2-fold increase of lymphocytes capable to form specific rosettes with xenogenous erythrocytes. T-lymphocytes were greatly sensitive to the laser influence. Acute laser exposure (128 sec) induced changes similar to Novocain action (1/2 LD50). Five-fold increase of the laser exposure time (especially for low frequency regime) resulted in more prominent changes in intercellular communication which were found to be similar to the action of Acrylamide (1/2 LD50). B-lymphocytes and splenocytes have been assumed as target cells for the action of laser with the frequency of 1500 Hz. Course application of IR or He-Ne laser induced decrease of RFA for all immune cells tested, and for blood lymphocytes, respectively. Thus, laser-induced changes in immune cells interaction may be connected with reversible injury of cell surface membrane followed by the dysregulation of cellular communication. Based on experimental data, the optimal regime of IR laserotherapy (0.89 and 0.63 micrometer) was chosen for the treatment of 200 patients with chronic decompensated tonsillitis. Efficiency of laser application was confirmed by cytological analysis of lacunes, laserodopplerofluometria, vegetative nervous system evaluation etc. and was found to be dependent on membranotropic activity of laser irradiation.

Insulator for laser housing

DOEpatents

Duncan, D.B.

1992-12-29

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member. 3 figs.

Insulator for laser housing

DOEpatents

Duncan, David B.

1992-01-01

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member.

Study on off-axis detection of pulsed laser in atmosphere

NASA Astrophysics Data System (ADS)

Liang, Weiwei

2018-02-01

Laser communication, designation, and ranging are point to point and have a high degree of specificity, current laser detection, such as laser warning receiver system, could detect the scattering laser from the off-axis distance by scattering track on natural aerosols, which is helpful to locate the laser source. However, the intensity of the scattering laser is extremely weak and affected by many factors, in order to evaluate the detection characteristic, a simplified model of off-axis detection for scattering laser in the lower atmosphere based on the Mie scattering theory is presented in this paper, the performances of the off-axis laser detection in different conditions such as off-axis distance, visibility, incidence angle, and delay time are investigated.

Insulative laser shell coupler

DOEpatents

Arnold, Phillip A.; Anderson, Andrew T.; Alger, Terry W.

1994-01-01

A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

Insulative laser shell coupler

DOEpatents

Arnold, P.A.; Anderson, A.T.; Alger, T.W.

1994-09-20

A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dielectric break ring, and a pair of threaded ring sections is disclosed. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections. 4 figs.

Spacecraft system study: A study to define the impact of laser communication systems on their host spacecraft

NASA Technical Reports Server (NTRS)

1984-01-01

The mutual influence of a laser communication system and its host spacecraft and the degree to which the mutual influence limited acquisition, tracking and pointing processes were investigated. A laser klink between a low earth orbiting (LEO) satellite and a geosynchronous earth orbiting (GEO) satellite was used as a baseline. The laser link between satellites was a generic channel transferring 500 Mbps data from the LEO to GEO using the GaAlAs laser as the laser light source. Major aspects of pointing and tracking with a satelliteborne optical system were evaluated including: (1) orbital aspects such as spacecraft relative motions, point ahead, and Sun snd Moon optical noise; (2) burst errors introduced by the electronic and optical noise levels; (3) servo system design and configurations, and the noise sources such as, sensor noise, base motion disturbances, gimbal friction torque noise; (4) an evaluation of the tracking and beacon link and the type of sensors used; (5) the function of the acquisition procedure and an evaluation of the sensors employed; and (6) an estimate of the size, weight and power needed for the satellite system.

External control of semiconductor nanostructure lasers

NASA Astrophysics Data System (ADS)

Naderi, Nader A.

2011-12-01

Novel semiconductor nanostructure laser diodes such as quantum-dot and quantum-dash are key optoelectronic candidates for many applications such as data transmitters in ultra fast optical communications. This is mainly due to their unique carrier dynamics compared to conventional quantum-well lasers that enables their potential for high differential gain and modified linewidth enhancement factor. However, there are known intrinsic limitations associated with semiconductor laser dynamics that can hinder the performance including the mode stability, spectral linewidth, and direct modulation capabilities. One possible method to overcome these limitations is through the use of external control techniques. The electrical and/or optical external perturbations can be implemented to improve the parameters associated with the intrinsic laser's dynamics, such as threshold gain, damping rate, spectral linewidth, and mode selectivity. In this dissertation, studies on the impact of external control techniques through optical injection-locking, optical feedback and asymmetric current bias control on the overall performance of the nanostructure lasers were conducted in order to understand the associated intrinsic device limitations and to develop strategies for controlling the underlying dynamics to improve laser performance. In turn, the findings of this work can act as a guideline for making high performance nanostructure lasers for future ultra fast data transmitters in long-haul optical communication systems, and some can provide an insight into making a compact and low-cost terahertz optical source for future implementation in monolithic millimeter-wave integrated circuits.

Electro-optic harmonic conversion to switch a laser beam out of a cavity

DOEpatents

Haas, R.A.; Henesian, M.A.

1984-10-19

The present invention relates to switching laser beams out of laser cavities, and more particularly, it relates to the use of generating harmonics of the laser beam to accomplish the switching. When laser light is generatd in a laser cavity the problem arises of how to switch the laser light out of the cavity in order to make use of the resulting laser beam in a well known multitude of ways. These uses include range finding, communication, remote sensing, medical surgery, laser fusion applications and many more. The switch-out problem becomes more difficult as the size of the laser aperture grows such as in laser fusion applications. The final amplifier stages of the Nova and Novette lasers at Lawrence Livermore National Laboratory are 46 centimeters with the laser beam expanded to 74 centimeters thereafter. Larger aperture lasers are planned.

Development of a Handheld Line Information Reader and Generator for Efficient Management of Optical Communication Lines

PubMed Central

Lee, Jaeyul; Kwon, Hyungwoo; Song, Jaewon; Jeon, Mansik; Kim, Jeehyun

2017-01-01

A handheld line information reader and a line information generator were developed for the efficient management of optical communication lines. The line information reader consists of a photo diode, trans-impedance amplifier, voltage amplifier, microcontroller unit, display panel, and communication modules. The line information generator consists of a laser diode, laser driving circuits, microcontroller unit, and communication modules. The line information reader can detect the optical radiation field of the test line by bending the optical fiber. To enhance the sensitivity of the line information reader, an additional lens was used with a focal length of 4.51 mm. Moreover, the simulation results obtained through BeamPROP® software from Synopsys, Inc. demonstrated a stronger optical radiation field of the fiber due to a longer transmission wavelength and larger bending angle of the fiber. Therefore, the developed devices can be considered as useful tools for the efficient management of optical communication lines. PMID:28837058

A Theoretical Model Analysis of Absorption of a Three level Diode Pumped Alkali Laser

DTIC Science & Technology

2009-03-01

2.10) 103 Bibliography Demtroder, Wolfgang . Laser Spectroscopy: Basic Concepts and Instrumentation. Berlin: Springer...Konefal Z., “Observation of collision induced processes in rubidium-ethane vapour,” Optics Communication, 164:95-105 (1999). Krause , L

Multi-Gigabit Free-Space Optical Data Communication and Network System

DTIC Science & Technology

2016-04-01

IR), Ultraviolet ( UV ), Laser Transceiver, Adaptive Beam Tracking, Electronic Attack (EA), Cyber Attack, Multipoint-to-Multipoint Network, Adaptive...FileName.pptx Free Space Optical Datalink Timeline Phase 1 Point-to-point demonstration 2012 Future Adaptive optic & Quantum Cascade Laser

Every Good Virtue You Ever Wanted in a Q-switched Solid-state Laser and More: Monolithic, Diode-pumped, Self-q-switched, Highly Reproducible, Diffraction-limited Nd:yag Laser

NASA Technical Reports Server (NTRS)

Chen, Y. C.; Lee, K. K.

1993-01-01

The applications of Q-switched lasers are well known, for example, laser radar, laser remote sensing, satellite orbit determination, Moon orbit and 'moon quake' determination, satellite laser communication, and many nonlinear optics applications. Most of the applications require additional properties of the Q-switched lasers, such as single-axial and/or single-transverse mode, high repetition rate, stable pulse shape and pulse width, or ultra compact and rugged oscillators. Furthermore, space based and airborne lasers for lidar and laser communication applications require efficient, compact, lightweight, long-lived, and stable-pulsed laser sources. Diode-pumped solid-state lasers (DPSSL) have recently shown the potential for satisfying all of these requirements. We will report on the operating characteristics of a diode-pumped, monolithic, self-Q-switched Cr,Nd:YAG laser where the chromium ions act as a saturable absorber for the laser emission at 1064 nm. The pulse duration is 3.5 ns and the output is highly polarized with an extinction ratio of 700:1. It is further shown that the output is single-longitudinal-mode with transform-limited spectral line width without pulse-to-pulse mode competition. Consequently, the pulse-to-pulse intensity fluctuation is less than the instrument resolution of 0.25 percent. This self-stabilization mechanism is because the lasing mode bleaches the distributed absorber and establishes a gain-loss grating similar to that used in the distributed feedback semiconductor lasers. A repetition rate above 5 KHz has also been demonstrated. For higher power, this laser can be used for injection seeding an amplifier (or amplifier chain) or injection locking of a power oscillator pumped by diode lasers. We will discuss some research directions on the master oscillator for higher output energy per pulse as well as how to scale the output power of the diode-pumped amplifier(s) to multi-kilowatt average power.

Direct-detection Free-space Laser Transceiver Test-bed

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Chen, Jeffrey R.; Dabney, Philip W.; Ferrara, Jeffrey F.; Fong, Wai H.; Martino, Anthony J.; McGarry Jan. F.; Merkowitz, Stephen M.; Principe, Caleb M.; Sun, Siaoli;

Laser Communications Relay Demonstration: Introduction for Experimenters

NASA Technical Reports Server (NTRS)

Israel, David J.

2017-01-01

This document provides guidance to individuals or groups considering proposing an experiment for the Laser Communications Relay Demonstration (LCRD) Experiment Program. For the purposes of this document, the term experiment refers to both experiments and demonstrations. The documents goals are: (1) to introduce potential experimenters to the LCRD mission, its purpose, and its system architecture; (2) to help them understand the types of experiments that are possible using LCRD; and (3) to provide an overview of the experiment proposal process and explain how and where to obtain further information about making a proposal.

Free Space Optical Communication Utilizing Mid-Infrared Interband Cascade Laser

NASA Technical Reports Server (NTRS)

Soibel, A.; Wright, M.; Farr, W.; Keo, S.; Hill, C.; Yang, R. Q.; Liu, H. C.

2010-01-01

A Free Space Optical (FSO) link utilizing mid-IR Interband Cascade lasers has been demonstrated in the 3-5 micron atmospheric transmission window with data rates up to 70 Mb/s and bit-error-rate (BER) less than 10 (exp -8). The performance of the mid-IR FSO link has been compared with the performance of a near-IR link under various fog conditions using an indoor communication testbed. These experiments demonstrated the lower attenuation and scintillation advantages of a mid-IR FSO link through fog than a 1550 nm FSO link.

Effect of atmospheric anisoplanatism on earth-to-satellite time transfer over laser communication links.

PubMed

Belmonte, Aniceto; Taylor, Michael T; Hollberg, Leo; Kahn, Joseph M

2017-07-10

The need for an accurate time reference on orbiting platforms motivates study of time transfer via free-space optical communication links. The impact of atmospheric turbulence on earth-to-satellite optical time transfer has not been fully characterized, however. We analyze limits to two-way laser time transfer accuracy posed by anisoplanatic non-reciprocity between uplink and downlink. We show that despite limited reciprocity, two-way time transfer can still achieve sub-picosecond accuracy in realistic propagation scenarios over a single satellite visibility period.

Increasing the critical thickness of InGaAs quantum wells using strain-relief technologies

NASA Astrophysics Data System (ADS)

Jones, Andrew Marquis

The advantages of optical communication through silica fiber have made long-distance electrical communication through copper wire obsolete. The two windows of operation for long-haul optical communication are centered around the wavelengths of 1.3 mum and 1.55 mum, which have minimal amounts of signal attenuation and dispersion. Benefits of optical communications within these windows include low system costs, high bandwidth, and high system reliability which have encouraged the development of emitters and receivers at these relatively long wavelengths. Long-wavelength semiconductor lasers are typically fabricated on InP substrates, but their performance suffers greatly with increases in operating temperature. Laser diodes on GaAs substrates are not as sensitive to operating temperature due to quantum-well active regions with relative deep potential barriers, but critical thickness limits the wavelength ceiling to 1.1 mum. Strain-relief technologies are currently being investigated to enable long-wavelength lasers with deeper potential wells leading to a corresponding increase in characteristic temperatures. Having a larger lattice constant than GaAs enables ternary InGaAs substrates to increase the 1.1-mum wavelength ceiling. Extending this ceiling to one of the optical communication windows could enable high-characteristic-temperature, long-wavelength lasers. Broad-area and buried-heterostructure lasers have demonstrated the potential of ternary substrates to increase characteristic temperatures and emission wavelengths. Wavelengths as long as 1.15 mum and characteristic temperatures as high as 145 K have been achieved. Reduced-area metalorganic chemical vapor deposition involves the deposition of strained materials on isolated islands. Due to the discontinuous nature of reduced-area epitaxy, strained materials are allowed to expand near the mesa edges, decreasing the overall strain in the structure. Laser diodes using this technology have been successfully fabricated, and evidence for partial relief of strain energy has been obtained. Compliant membranes enable strain relief by depositing on an ultra-thin semiconductor base. Unlike growth on typical thick substrates, expansion of the compliant membrane during strained-layer regrowth allows the membrane to accommodate most of the strain energy. Ternary InGaAs compliant films supported above a GaAs substrate with single AlGaAs pedestals have been utilized to fabricate long-wavelength (1.35 mum) InGaAs quantum wells on a GaAs substrate.

Development of Operational Free-Space-Optical (FSO) Laser Communication Systems Final Report CRADA No. TC02093.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruggiero, A.; Orgren, A.

This project was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermore National Laboratory (LLNL) and LGS Innovations, LLC (formerly Lucent Technologies, Inc.), to develop long-range and mobile operational free-space optical (FSO) laser communication systems for specialized government applications. LLNL and LGS Innovations formerly Lucent Bell Laboratories Government Communications Systems performed this work for a United States Government (USG) Intelligence Work for Others (I-WFO) customer, also referred to as "Government Customer", or "Customer" and "Government Sponsor." The CRADA was a critical and required part of the LLNL technology transfer plan formore » the customer.« less

Ultra-Sensitive Photoreceiver Boosts Data Transmission

NASA Technical Reports Server (NTRS)

2007-01-01

NASA depends on advanced, ultra-sensitive photoreceivers and photodetectors to provide high-data communications and pinpoint image-detection and -recognition capabilities from great distances. In 2003, Epitaxial Technologies LLC was awarded a Small Business Innovation Research (SBIR) contract from Goddard Space Flight Center to address needs for advanced sensor components. Epitaxial developed a photoreciever capable of single proton sensitivity that is also smaller, lighter, and requires less power than its predecessor. This receiver operates in several wavelength ranges; will allow data rate transmissions in the terabit range; and will enhance Earth-based missions for remote sensing of crops and other natural resources, including applications for fluorescence and phosphorescence detection. Widespread military and civilian applications are anticipated, especially through enhancing fiber optic communications, laser imaging, and laser communications.

Multi-access laser communications transceiver system

NASA Technical Reports Server (NTRS)

Ross, Monte (Inventor); Lokerson, Donald C. (Inventor); Fitzmaurice, Michael W. (Inventor); Meyer, Daniel D. (Inventor)

1993-01-01

A satellite system for optical communications such as a multi-access laser transceiver system. Up to six low Earth orbiting satellites send satellite data to a geosynchronous satellite. The data is relayed to a ground station at the Earth's surface. The earth pointing geosynchronous satellite terminal has no gimbal but has a separate tracking mechanism for tracking each low Earth orbiting satellite. The tracking mechanism has a ring assembly rotatable about an axis coaxial with the axis of the field of view of the geosynchronous satellite and a pivotable arm mounted for pivotal movement on the ring assembly. An optical pickup mechanism at the end of each arm is positioned for optical communication with one of the orbiting satellites by rotation of the ring.

Optical Communications Transmitter

NASA Image and Video Library

1965-11-10

S65-42598 (10 Nov. 1965) --- Douglas S. Idlly, Electromagnetic Systems Branch, Instrumentation and Electronic Systems Division, illustrates an Optical Communications Transmitter (LASER) during a briefing at the news center of the Manned Spacecraft Center in Houston, Texas. Photo credit: NASA

Centroid measurement error of CMOS detector in the presence of detector noise for inter-satellite optical communications

NASA Astrophysics Data System (ADS)

Li, Xin; Zhou, Shihong; Ma, Jing; Tan, Liying; Shen, Tao

2013-08-01

CMOS is a good candidate tracking detector for satellite optical communications systems with outstanding feature of sub-window for the development of APS (Active Pixel Sensor) technology. For inter-satellite optical communications it is critical to estimate the direction of incident laser beam precisely by measuring the centroid position of incident beam spot. The presence of detector noise results in measurement error, which degrades the tracking performance of systems. In this research, the measurement error of CMOS is derived taking consideration of detector noise. It is shown that the measurement error depends on pixel noise, size of the tracking sub-window (pixels number), intensity of incident laser beam, relative size of beam spot. The influences of these factors are analyzed by numerical simulation. We hope the results obtained in this research will be helpful in the design of CMOS detector satellite optical communications systems.

First Experimental Demonstration of Full-Duplex Optical Communication on a Single Beam

NASA Technical Reports Server (NTRS)

Garrett, Christopher David; Shay, Thomas

2001-01-01

The satellite industry is driven by the need to reduce costs. One way they have sought to do this is by reducing the size and weight of the satellite because of the extremely high cost per kilogram incurred launching a payload into orbit. The main difficulty in this approach is the lack of power capacity in a small satellite. One of the largest loads on a satellite's power system is the communications system. This has driven the need for a low-power communications system. This document examines a novel method of communicating optically with a low-Earth-orbit satellite from the ground without the need for a laser on the payload. The goal is to show the feasibility of such a system as a solution to the small satellite low-powered communication problem. Specially, that the system described herein: is capable of ground to low-Earth-orbit communications, has very little space-borne mass, and draws little power from the satellite. First, the system (hereafter referred to as LOWCAL "Lightweight Optical Wavelength Communication without A Laser in space") will be explained with details of the formats used and the link budgets. Discussions will be presented on the development of some of the system hardware (the laser diode driver, liquid crystal driver, and decision electronics for both the up and down links.) Finally, experimental test results of the entire system operating in a laboratory environment are presented and compared to theory. The results of the laboratory experiment support the original thesis: retro-modulated optical communications can meet the needs of the small satellite community. The system is capable of 10-kbps communication, has low space-borne mass, and draws little power from the satellite (less than 100-mW measured for the laboratory experiment, less than 1.5-W calculated for the Shuttle experiment).

Free-space, laser-based data transmission: satellite communication as a technology driver for the development of fast, reliable terrestrial data networks

NASA Astrophysics Data System (ADS)

Gerken, Martin; Luichtel, Georg

2008-04-01

High-resolution digital images with high refresh rates cause an enormous amount of data that must be forwarded from the source to the recipient. This is where wireless transmission as an RF technology quickly reaches its limits. With its high bandwidth, laser-based data transmission avoids this problem. An added benefit is a higher level of security against eavesdropping that can be further increased through the use of quantum optical encryption techniques. For military applications, several scenarios will be considered. Especially for the navy, communication between a ship and land for remote forces using free space air at the eye-safe laser wavelength of 1550 nm is necessary. Data transfer at this wavelength between ships is also important for an exchange of tactical images of the local situation. In the future, the direct communication between a ship and a submarine through water will be required. Bug-proof and broad bandwidth transmission of reconnaissance data will be necessary over distances of approx. several 100 m at the laser wavelength of 532 nm. This paper will show how experiences gained through the development of optical data links from satellites to ground stations can be used as an enabling technology for additional applications for the development of stable data connections under atmospheric conditions.

Submarine laser communications

NASA Astrophysics Data System (ADS)

McConathy, D. R.

The Department of the Navy and the Defense Advanced Research Projects Agency (DARPA) are sponsoring a joint study to investigate the use of blue-green laser technology to comunicate with submarines at operating depths. Two approaches are under investigation - one in which the laser itself is space-based, and the other in which the laser is ground-based with its beam redirected to the earth's surface by an orbiting mirror. This paper discusses these two approaches, and presents a brief history of activities which led to the current studies.

Laser data transfer flight experiment definition

NASA Technical Reports Server (NTRS)

Merritt, J. R.

1975-01-01

A set of laser communication flight experiments to be performed between a relay satellite, ground terminals, and space shuttles were synthesized and evaluated. Results include a definition of the space terminals, NASA ground terminals, test methods, and test schedules required to perform the experiments.

Improving the Reliability and Modal Stability of High Power 870 nm AlGaAs CSP Laser Diodes for Applications to Free Space Communication Systems

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Alphonse, G. A.; Carlin, D. B.; Ettenberg, M.

1991-01-01

The operating characteristics (power-current, beam divergence, etc.) and reliability assessment of high-power CSP lasers is discussed. The emission wavelength of these lasers was optimized at 860 to 880 nm. The operational characteristics of a new laser, the inverse channel substrate planar (ICSP) laser, grown by metalorganic chemical vapor deposition (MOCVD), is discussed and the reliability assessment of this laser is reported. The highlights of this study include a reduction in the threshold current value for the laser to 15 mA and a degradation rate of less than 2 kW/hr for the lasers operating at 60 mW of peak output power.

Growth and Evaluation of Nonlinear Optical Crystals for Laser Applications: Lithium Borate, Barium Borate and Silver Gallium Selenide.

DTIC Science & Technology

1994-12-08

communication 2. S. A. Kutovi, V. V. Laptev and S. Yu. Matsnev, " Lanthanum scandoborate as a new highly efficient active medium of solid state lasers," Sov. J...34Noncritical detection of tunable C02 laser radiation into green by upconversion in silver thio- gallate ," Applied Physics B53, 19 (1991). 3. N.-H

InGaAsN/GaAs Heterostructures for Long-Wavelength Light-Emitting Devices

DTIC Science & Technology

2000-06-23

vertical cavity surface emitting lasers ( VCSELs ) on GaAs is expected to be possible by... molecular beam epitaxy using an RF plasma-source. Broad area and ridge waveguide laser structures based on such QWs exhibit performance that can...work with GaAs/AlAs DBR-mirrors is expected to lead to novel vertical cavity lasers for optical fiber communication systems. Acknowledgement

Light pollution generated by laser guide star at Canarian Observatories

NASA Astrophysics Data System (ADS)

Chueca, Sergio; Fuensalida, Jesus J.

2004-11-01

A new generation of instrument using a launching laser is been developed to correct the atmospheric image blurring and to establish optical communication with space. Then, light pollution generated by laser will be a serious operational problem in next years. This laser could affect astronomical works of adjacent telescopes when the laser lay across the field of view of the observing telescope, this is a kind of light pollution. This could be avoided with an adequate operational politic to detect possible interference between the laser and the astronomical telescopes. In this paper is analysed the mathematical probability of a cross-event happen.

Theoretical model for frequency locking a diode laser with a Faraday cell

NASA Technical Reports Server (NTRS)

Wanninger, P.; Shay, T. M.

1992-01-01

A new method was developed for frequency locking a diode lasers, called 'the Faraday anomalous dispersion optical transmitter (FADOT) laser locking', which is much simpler than other known locking schemes. The FADOT laser locking method uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. The FADOT method is vibration insensitive and exhibits minimal thermal expansion effects. The system has a frequency pull in the range of 443.2 GHz (9 A). The method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters.

Novel Optical SETI Observations of Three Exoplanets

NASA Astrophysics Data System (ADS)

Welsh, Barry; Vallerga, John; Kotze, Marissa; Wheatley, Jonathan

2018-01-01

We report on observations of three nearby stars (Trappist-1, GJ 422 and Wolf 1061) that possess exoplanets located in their respective habitable zones to search for optical signals generated by an advanced alien civilization. Using the photon data collected with the Berkeley Visible Image Tube attached to the 10m Southern African Large Telescope, we searched for very high amplitude events in the pulse height distributions that statistically could only be produced by non-astrophysical means such as an optical laser used for communications purposes.Assuming that a purported ET civilization has access to an orbiting 10m mirror and an optical laser to send signals over the three sight-lines to Earth, we derive upper limits to the output power of their l lasers which might be used for inter-stellar communication.

CW laser use in biomedical research and practice

NASA Astrophysics Data System (ADS)

Matthopoulos, D. P.

2003-04-01

The communication of humans with their surrouding is achieved through their senses and the related organs. Visual communication using the eyes is made possible because the various sources of light, natural i.e. the sun or the lightning, or artificial such as Lasers, emit electromagnetic radiation which is either reflected or scattered by surfaces. This radiation received by eyes is processed in the brain where the images of the environment are developed. The luminous processing can be either macro- or microscopic. The macroscopic processing is the result of light coming from the sun or from wide range lamps, while the microscopic results from light coming from wide range lamps, mercury lamps, lasers or electron beam. The microscopic processing is the subject we are dealing with in this presentation.

Concepts for fast acquisition in optical communications systems

NASA Astrophysics Data System (ADS)

Wilkerson, Brandon L.; Giggenbach, Dirk; Epple, Bernhard

2006-09-01

As free-space laser communications systems proliferate due to improved technology and transmission techniques, optical communication networks comprised of ground stations, aircraft, high altitude platforms, and satellites become an attainable goal. An important consideration for optical networks is the ability of optical communication terminals (OCT) to quickly locate one another and align their laser beams to initiate the acquisition sequence. This paper investigates promising low-cost technologies and novel approaches that will facilitate the targeting and acquisition tasks between counter terminals. Specifically, two critical technology areas are investigated: position determination (which includes location and attitude determination) and inter-terminal communications. A feasibility study identified multiple-antenna global navigation satellite system (GNSS) systems and GNSS-aided inertial systems as possible position determination solutions. Personal satellite communication systems (e.g. Iridium or Inmarsat), third generation cellular technology (IMT-2000/UMTS), and a relatively new air traffic surveillance technology called Autonomous Dependent Surveillance-Broadcast (ADS-B) were identified as possible inter-terminal communication solutions. A GNSS-aided inertial system and an ADS-B system were integrated into an OCT to demonstrate their utility in a typical optical communication scenario. Testing showed that these technologies have high potential in future OCTs, although improvements can be made to both to increase tracking accuracy.

High-speed laser communications in UAV scenarios

NASA Astrophysics Data System (ADS)

Griethe, Wolfgang; Gregory, Mark; Heine, Frank; Kämpfner, Hartmut

2011-05-01

Optical links, based on coherent homodyne detection and BPSK modulation with bidirectional data transmission of 5.6 Gbps over distances of about 5,000 km and BER of 10-8, have been sufficiently verified in space. The verification results show that this technology is suitable not only for space applications but also for applications in the troposphere. After a brief description of the Laser Communication Terminal (LCT) for space applications, the paper consequently discusses the future utilization of satellite-based optical data links for Beyond Line of Sight (BLOS) operations of High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV). It is shown that the use of optical frequencies is the only logical consequence of an ever-increasing demand for bandwidth. In terms of Network Centric Warfare it is highly recommended that Unmanned Aircraft Systems (UAS) of the future should incorporate that technology which allows almost unlimited bandwidth. The advantages of optical communications especially for Intelligence, Surveillance and Reconnaissance (ISR) are underlined. Moreover, the preliminary design concept of an airborne laser communication terminal is described. Since optical bi-directional links have been tested between a LCT in space and a TESAT Optical Ground Station (OGS), preliminary analysis on tracking and BER performance and the impact of atmospheric disturbances on coherent links will be presented.

A wireless laser displacement sensor node for structural health monitoring.

PubMed

Park, Hyo Seon; Kim, Jong Moon; Choi, Se Woon; Kim, Yousok

2013-09-30

This study describes a wireless laser displacement sensor node that measures displacement as a representative damage index for structural health monitoring (SHM). The proposed measurement system consists of a laser displacement sensor (LDS) and a customized wireless sensor node. Wireless communication is enabled by a sensor node that consists of a sensor module, a code division multiple access (CDMA) communication module, a processor, and a power module. An LDS with a long measurement distance is chosen to increase field applicability. For a wireless sensor node driven by a battery, we use a power control module with a low-power processor, which facilitates switching between the sleep and active modes, thus maximizing the power consumption efficiency during non-measurement and non-transfer periods. The CDMA mode is also used to overcome the limitation of communication distance, which is a challenge for wireless sensor networks and wireless communication. To evaluate the reliability and field applicability of the proposed wireless displacement measurement system, the system is tested onsite to obtain the required vertical displacement measurements during the construction of mega-trusses and an edge truss, which are the primary structural members in a large-scale irregular building currently under construction. The measurement values confirm the validity of the proposed wireless displacement measurement system and its potential for use in safety evaluations of structural elements.

Chaos and Cryptography: A new dimension in secure communications

NASA Astrophysics Data System (ADS)

Banerjee, Santo; Kurths, J.

2014-06-01

This issue is a collection of contributions on recent developments and achievements of cryptography and communications using chaos. The various contributions report important and promising results such as synchronization of networks and data transmissions; image cipher; optical and TDMA communications, quantum keys etc. Various experiments and applications such as FPGA, smartphone cipher, semiconductor lasers etc, are also included.

AlGaInN laser diode technology and systems for defence and security applications

NASA Astrophysics Data System (ADS)

Najda, Stephen P.; Perlin, Piotr; Suski, Tadek; Marona, Lucja; Boćkowski, Mike; Leszczyński, Mike; Wisniewski, Przemek; Czernecki, Robert; Kucharski, Robert; Targowski, Grzegorz; Watson, Scott; Kelly, Antony E.

2015-05-01

The latest developments in AlGaInN laser diode technology are reviewed for defence and security applications such as underwater communications. The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well. Thus AlGaInN laser diode technology is a key enabler for the development of new disruptive system level applications in displays, telecom, defence and other industries.

LASER RADIATION CHARACTERISTICS (BRIEF COMMUNICATIONS): Conversion of KrCl and XeCl laser radiation to the visible spectral range by stimulated Raman scattering in lead vapor

NASA Astrophysics Data System (ADS)

Evtushenko, Gennadii S.; Mel'chenko, S. V.; Panchenko, Aleksei N.; Tarasenko, Viktor F.

1990-04-01

Conversion of KrCl and XeCl laser radiation by stimulated Raman scattering was achieved in lead vapor. The KrCl laser radiation was converted into three lines in the visible region at λ = 406, 590, and 723 nm by transitions from both the ground and first excited levels of the lead atom. The conversion efficiency of XeCl laser radiation of low spatial coherence was found to be limited by the activation of a competing nonlinear process.

Space Operation of the MOLA Laser

NASA Technical Reports Server (NTRS)

Afzal, Robert S.

2000-01-01

Interest in lasers for space applications such as active remote sensing in Earth orbit, planetary science, and inter-satellite laser communications is growing. These instruments typically use diode-pumped solid state lasers for the laser transmitter. The mission specifications and constraints of space qualification, place strict requirements on the design and operation of the laser. Although a laser can be built in the laboratory to meet performance specifications relatively routinely, tile mission constraints demand unique options and compromises in the materials used, and design to ensure the success of the mission. Presently, the best laser architecture for a light weight, rugged, high peak power and efficient transmitter is a diode laser pumped ND:YAG laser. Diode lasers can often obviate the need for water cooling, reduce the size and weight of the laser, increase the electrical to optical efficiency, system reliability, and lifetime. This paper describes the in-space operation and performance of the Mars Orbiter Laser Altimeter (MOLA) laser transmitter, representing the current state-of-the-art in space-based solid- state lasers.

Multi-rate DPSK optical transceivers for free-space applications

NASA Astrophysics Data System (ADS)

Caplan, D. O.; Carney, J. J.; Fitzgerald, J. J.; Gaschits, I.; Kaminsky, R.; Lund, G.; Hamilton, S. A.; Magliocco, R. J.; Murphy, R. J.; Rao, H. G.; Spellmeyer, N. W.; Wang, J. P.

2014-03-01

We describe a flexible high-sensitivity laser communication transceiver design that can significantly benefit performance and cost of NASA's satellite-based Laser Communications Relay Demonstration. Optical communications using differential phase shift keying, widely deployed for use in long-haul fiber-optic networks, is well known for its superior sensitivity and link performance over on-off keying, while maintaining a relatively straightforward design. However, unlike fiber-optic links, free-space applications often require operation over a wide dynamic range of power due to variations in link distance and channel conditions, which can include rapid kHz-class fading when operating through the turbulent atmosphere. Here we discuss the implementation of a robust, near-quantum-limited multi-rate DPSK transceiver, co-located transmitter and receiver subsystems that can operate efficiently over the highly-variable free-space channel. Key performance features will be presented on the master oscillator power amplifier (MOPA) based TX, including a wavelength-stabilized master laser, high-extinction-ratio burst-mode modulator, and 0.5 W single polarization power amplifier, as well as low-noise optically preamplified DSPK receiver and built-in test capabilities.

Blue Laser Diode Enables Underwater Communication at 12.4 Gbps

PubMed Central

Wu, Tsai-Chen; Chi, Yu-Chieh; Wang, Huai-Yung; Tsai, Cheng-Ting; Lin, Gong-Ru

2017-01-01

To enable high-speed underwater wireless optical communication (UWOC) in tap-water and seawater environments over long distances, a 450-nm blue GaN laser diode (LD) directly modulated by pre-leveled 16-quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) data was employed to implement its maximal transmission capacity of up to 10 Gbps. The proposed UWOC in tap water provided a maximal allowable communication bit rate increase from 5.2 to 12.4 Gbps with the corresponding underwater transmission distance significantly reduced from 10.2 to 1.7 m, exhibiting a bit rate/distance decaying slope of −0.847 Gbps/m. When conducting the same type of UWOC in seawater, light scattering induced by impurities attenuated the blue laser power, thereby degrading the transmission with a slightly higher decay ratio of 0.941 Gbps/m. The blue LD based UWOC enables a 16-QAM OFDM bit rate of up to 7.2 Gbps for transmission in seawater more than 6.8 m. PMID:28094309

Simulating the performance of adaptive optics techniques on FSO communications through the atmosphere

NASA Astrophysics Data System (ADS)

Martínez, Noelia; Rodríguez Ramos, Luis Fernando; Sodnik, Zoran

2017-08-01

The Optical Ground Station (OGS), installed in the Teide Observatory since 1995, was built as part of ESA efforts in the research field of satellite optical communications to test laser telecommunication terminals on board of satellites in Low Earth Orbit and Geostationary Orbit. As far as one side of the link is settled on the Earth, the laser beam (either on the uplink or on the downlink) has to bear with the atmospheric turbulence. Within the framework of designing an Adaptive Optics system to improve the performance of the Free-Space Optical Communications at the OGS, turbulence conditions regarding uplink and downlink have been simulated within the OOMAO (Object-Oriented Matlab Adaptive Optics) Toolbox as well as the possible utilization of a Laser Guide Star to measure the wavefront in this context. Simulations have been carried out by reducing available atmospheric profiles regarding both night-time and day-time measurements and by having into account possible seasonal changes. An AO proposal to reduce atmospheric aberrations and, therefore, ameliorate FSO links performance is presented and analysed in this paper

Metasurface-assisted orbital angular momentum carrying Bessel-Gaussian Laser: proposal and simulation.

PubMed

Zhou, Nan; Wang, Jian

2018-05-23

Bessel-Gaussian beams have distinct properties of suppressed diffraction divergence and self-reconstruction. In this paper, we propose and simulate metasurface-assisted orbital angular momentum (OAM) carrying Bessel-Gaussian laser. The laser can be regarded as a Fabry-Perot cavity formed by one partially transparent output plane mirror and the other metasurface-based reflector mirror. The gain medium of Nd:YVO 4 enables the lasing wavelength at 1064 nm with a 808 nm laser serving as the pump. The sub-wavelength structure of metasurface facilitates flexible spatial light manipulation. The compact metasurface-based reflector provides combined phase functions of an axicon and a spherical mirror. By appropriately selecting the size of output mirror and inserting mode-selection element in the laser cavity, different orders of OAM-carrying Bessel-Gaussian lasing modes are achievable. The lasing Bessel-Gaussian 0 , Bessel-Gaussian 01 + , Bessel-Gaussian 02 + and Bessel-Gaussian 03 + modes have high fidelities of ~0.889, ~0.889, ~0.881 and ~0.879, respectively. The metasurface fabrication tolerance and the dependence of threshold power and output lasing power on the length of gain medium, beam radius of pump and transmittance of output mirror are also discussed. The obtained results show successful implementation of metasurface-assisted OAM-carrying Bessel-Gaussian laser with favorable performance. The metasurface-assisted OAM-carrying Bessel-Gaussian laser may find wide OAM-enabled communication and non-communication applications.

Optical frequency stabilization in infrared region using improved dual feed-back loop

NASA Astrophysics Data System (ADS)

Ružička, B.; Číp, O.; Lazar, J.

2007-03-01

Modern technologies such as DWDM (Dense Wavelength Division Multiplex) need precise stability of laser frequencies. According to this fact, requirements of new etalons of optical frequencies in the telecommunication band is rapidly growing. Lasers working in near infrared telecommunication band (1500-1600 nm) can be stabilized to 12C IIH II or 13C IIH II (acetylene) gas absorption lines. The acetylene gas absorption has been widely studied and accepted by international bodies of standardization as a primary wavelength reference in the near infrared band around 1550 nm. Our aim was to design and develop a compact fibre optics laser system generating coherent light in near-IR band with high frequency stability (at least 1.10 -8). This system should become a base for realization of a primary frequency standard for optical communications in the Czech Republic. Such an etalon will be needed for calibration of wavelengthmeters and spectral analysers for DWDM communication systems. We are co-operating with CMI (Czech Metrology Institute) on this project. We present stabilized laser system based on a single frequency DFB (Distributed Feedback) laser diode with a narrow spectral profile. The laser is pre-stabilized by means of the FM-spectroscopy on a passive resonator. Thanks to a fast feed-back loop we are able to improve spectral characteristics of the laser. The laser frequency is locked by a relatively slow second feed-back loop on an absorption line of acetylene vapour which is sealed in a cell under the optimised pressure.

Study of the blue-green laser scattering from the rough sea surface with foams by the improved two-scale method

NASA Astrophysics Data System (ADS)

Li, Xiangzhen; Qi, Xiao; Han, Xiang'e.

2015-10-01

The characteristics of laser scattering from sea surface have a great influence on application performance, from submarine communication, laser detection to laser diffusion communication. Foams will appear when the wind speed exceeds a certain value, so the foam can be seen everywhere in the upper layer of the ocean. Aiming at the volume-surface composite model of rough sea surface with foam layer driven by wind, and the similarities and differences of scattering characteristics between blue-green laser and microwave, an improved two-scale method for blue-green laser to calculate the scattering coefficient is presented in this paper. Based on the improved two-scale rough surface scattering theory, MIE theory and VRT( vector radiative transfer ) theory, the relations between the foam coverage of the sea surface and wind speed and air-sea temperature difference are analyzed. Aiming at the Gauss sea surface in blue-green laser, the dependence of back- and bistatie-scattering coefficient on the incident and azimuth angle, the coverage of foams, as well as the wind speed are discussed in detail. The results of numerical simulations are compared and analyzed in this paper. It can be concluded that the foam layer has a considerable effect on the laser scattering with the increase of wind speed, especially for a large incident angle. Theoretical analysis and numerical simulations show that the improved two-scale method is reasonable and efficient.

Experimental Investigation of Acousto-Optic Communications

DTIC Science & Technology

2003-09-01

acousto - optic sensor shows promise as a means for detecting acoustic data projected towards the water surface from a submerged platform. The laser...simulation studies were conducted to demonstrate acousto - optic sensor feasibility for obtaining robust recordings of acoustic communication signals across

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

DOEpatents

Berman, Gennady P [Los Alamos, NM; Bishop, Alan R [Los Alamos, NM; Nguyen, Dinh C [Los Alamos, NM; Chernobrod, Boris M [Santa Fe, NM; Gorshkov, Vacheslav N [Kiev, UA

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.

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 controller not only accurately estimates and compensates the disturbances, but also realizes the robustness to estimation of unknown dynamics. The controller can satisfy the requirement of fine tracking accuracy for free space optical communication system.

Optical superheterodyne receiver uses laser for local oscillator

NASA Technical Reports Server (NTRS)

Lucy, R. F.

1966-01-01

Optical superheterodyne receiver uses a laser coupled to a frequency translator to supply both the incident signal and local oscillator signal and thus permit reception of amplitude modulated video bandwidth signals through the atmosphere. This receiver is useful in scientific propagation experiments, tracking experiments, and communication experiments.

Optical Material Researches for Frontier Optical Ceramics and Visible Fiber Laser Technologies

DTIC Science & Technology

2016-07-07

zeolite method”, Motoichiro Murakami, Yasushi Fujimoto, Shinji Motokoshi, Tatsuhiro Sato, Hiroyuki Shiraga, Optics Communications 328 (2014) pp.121...Center, Shanghai, China. 13) “Rare Earth Doped Fiber Lasers Based on Zeolite Method - (invited)”, Y. Fujimoto, The 4th International Workshop on

The optical antenna system design research on earth integrative network laser link in the future

NASA Astrophysics Data System (ADS)

Liu, Xianzhu; Fu, Qiang; He, Jingyi

2014-11-01

Earth integrated information network can be real-time acquisition, transmission and processing the spatial information with the carrier based on space platforms, such as geostationary satellites or in low-orbit satellites, stratospheric balloons or unmanned and manned aircraft, etc. It is an essential infrastructure for China to constructed earth integrated information network. Earth integrated information network can not only support the highly dynamic and the real-time transmission of broadband down to earth observation, but the reliable transmission of the ultra remote and the large delay up to the deep space exploration, as well as provide services for the significant application of the ocean voyage, emergency rescue, navigation and positioning, air transportation, aerospace measurement or control and other fields.Thus the earth integrated information network can expand the human science, culture and productive activities to the space, ocean and even deep space, so it is the global research focus. The network of the laser communication link is an important component and the mean of communication in the earth integrated information network. Optimize the structure and design the system of the optical antenna is considered one of the difficulty key technologies for the space laser communication link network. Therefore, this paper presents an optical antenna system that it can be used in space laser communication link network.The antenna system was consisted by the plurality mirrors stitched with the rotational paraboloid as a substrate. The optical system structure of the multi-mirror stitched was simulated and emulated by the light tools software. Cassegrain form to be used in a relay optical system. The structural parameters of the relay optical system was optimized and designed by the optical design software of zemax. The results of the optimal design and simulation or emulation indicated that the antenna system had a good optical performance and a certain reference value in engineering. It can provide effective technical support to realize interconnection of earth integrated laser link information network in the future.

Mode Hopping in Semiconductor Lasers

NASA Astrophysics Data System (ADS)

Heumier, Timothy Alan

Semiconductor lasers have found widespread use in fiberoptic communications, merchandising (bar-code scanners), entertainment (videodisc and compact disc players), and in scientific inquiry (spectroscopy, laser cooling). Some uses require a minimum degree of stability of wavelength which is not met by these lasers: Under some conditions, semiconductor lasers can discontinuously switch wavelengths in a back-and-forth manner. This is called mode hopping. We show that mode hopping is directly correlated to noise in the total intensity, and that this noise is easily detected by a photodiode. We also show that there are combinations of laser case temperature and injection current which lead to mode hopping. Conversely, there are other combinations for which the laser is stable. These results are shown to have implications for controlling mode hopping.

A review of melasma treatment focusing on laser and light devices.

PubMed

Li, Janet Y; Geddes, Elizabeth Rc; Robinson, Deanne M; Friedman, Paul M

2016-12-01

Melasma is a pigmentary disorder of unclear etiology with numerous treatment options and high recurrence rates. Laser and light therapies may be utilized cautiously as second- or third-line options for recalcitrant melasma, but low-energy settings are preferred due to the risk of postinflammatory hyperpigmentation and melasma stimulation. Commonly used lasers include the low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, nonablative fractionated lasers, and intense pulsed light. Strict sun protection, concomitant use of bleaching agents, and maintenance treatments are necessary. A variety of other treatments that may also help to improve results are now being more widely adopted, including oral tranexamic acid, pulsed dye laser, antioxidants, and laser-assisted drug delivery. ©2016 Frontline Medical Communications.

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.

Nonlinear Detection, Estimation, and Control for Free-Space Optical Communication

DTIC Science & Technology

2008-08-17

original message. The promising features of this communication scheme such as high-bandwidth, power efficiency, and security, render it a viable means...bandwidth, power efficiency, and security, render it a viable means for high data rate point-to-point communication. In this dissertation, we adopt a...Department of Electrical and Computer Engineering In free-space optical communication, the intensity of a laser beam is modulated by a message, the beam

Science& Technology Review December 2002

DOE Office of Scientific and Technical Information (OSTI.GOV)

Budil, K S

2002-10-28

This issue has the following articles: (1) ''Doing It All: Sustaining Our Working Solutions, Rising to New Challenges''; (2) ''Emerging from the Cold War: Stockpile Stewardship and Beyond''--When the Cold War ended, Lawrence Livermore stepped up to a new national challenge--maintaining the safety and reliability of the U.S. nuclear stockpile without underground testing. (3) ''Machines from Interlocking Molecules''--Fundamental chemistry and physics research will enable scientists to control and use individual molecules. (4) ''Laser Zaps Communication Bottleneck''--Using laser communications, the U.S. military will be able to transmit data from advanced remote sensors in real time.

Large aperture segmented optics for space-to-ground communications.

PubMed

Lucy, R F

1968-08-01

A large aperture, moderate quality segmented optical array for use in noncoherent space-to-ground laser communications is determined as a function of resolution, diameter, focal length, and number of segments in the array. Secondary optics and construction tolerances are also discussed. Performance predictions show a typical receiver to be capable of megahertz communications at Mars distances during daylight operation.

Networked Multimedia: Are We There Yet?

ERIC Educational Resources Information Center

Wyman, Bill

1997-01-01

Discusses the technological advances in electronic communication over the last 30 years. Touches on various real-time interactive multimedia communications, including video on demand, videocassettes, laser discs, CD-ROM, a history of networking, terminal/host and client/server networking, intraoperability and interoperability and multimedia…

NASA direct detection laser diode driver

NASA Technical Reports Server (NTRS)

Seery, B. D.; Hornbuckle, C. A.

1989-01-01

TRW has developed a prototype driver circuit for GaAs laser diodes as part of the NASA/Goddard Space Flight Center's Direct Detection Laser Transceiver (DDLT) program. The circuit is designed to drive the laser diode over a range of user-selectable data rates from 1.7 to 220 Mbps, Manchester-encoded, while ensuring compatibility with 8-bit and quaternary pulse position modulation (QPPM) formats for simulating deep space communications. The resulting hybrid circuit has demonstrated 10 to 90 percent rise and fall times of less than 300 ps at peak currents exceeding 100 mA.

AlGaInN laser diode technology for free-space and plastic optical fibre telecom applications

NASA Astrophysics Data System (ADS)

Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Bóckowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.; Watson, S.; Kelly, A. E.; Watson, M. A.; Blanchard, P.; White, H.

2016-03-01

Gallium Nitride laser diodes fabricated from the AlGaInN material system is an emerging technology for laser sources from the UV to visible and is a potential key enabler for new system applications such as free-space (underwater & air bourne links) and plastic optical fibre telecommunications. We measure visible light (free-space and underwater) communications at high frequency (up to 2.5 Gbit/s) and in plastic optical fibre (POF) using a directly modulated GaN laser diode.

The European project Hippo high-power photonics for satellite laser communications and on-board optical processing

NASA Astrophysics Data System (ADS)

Kehayas, E.; Stampoulidis, L.; Henderson, P.; Robertson, Andrew; Van Dijk, F.; Achouche, M.; Le Kernec, A.; Sotom, M.; Schuberts, F.; Brabant, T.

2017-11-01

Photonics is progressively transforming from a highly- focused technology applicable to digital communication networks into a pervasive "enabling" technology with diverse non-telecom applications. However, the centre of mass on the R&D level is still mostly driven by, and invested in, by stakeholders active in the telecoms domain. This is due to the high level of investments necessary that in turn require a large and established market for reaching break-even and generation of revenues. Photonics technology and more specifically, fibre-optic technology is moving into non-telecom business areas with great success in terms of markets captured and penetration rates. One example that cannot be overlooked is the application of fibre-optics to industrial applications, where double-digit growth rates are recorded with fibre lasers and amplifiers constantly gaining momentum. In this example, several years of R&D efforts in creating high-power amplification solutions and fibre-laser sources by the telecom sector, were piggy-backed into industrial applications and laser cutting/welding equipment that is now a strong R&D sector on its own and commercially now displacing some conventional free space laser cutting/welding.

The formation and optical properties of planar waveguide in laser crystal Nd:YGG by carbon ion implantation

NASA Astrophysics Data System (ADS)

Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Jiao, Yang; Guan, Jing; Fu, Gang

2017-10-01

As one kind of prominent laser crystal, Nd:Y3Ga5O12 (Nd:YGG) crystal has outstanding performance on laser excitation at multi-wavelength which have shown promising applications in optical communication field. In addition, Nd:YGG crystal has potential applications in medical field due to its ability of emit the laser at 1110 nm. Optical waveguide structure with high quality could improve the efficiency of laser emission. In this work, we fabricated the optical planar waveguide on Nd:YGG crystal by medium mass ion implantation which was convinced an effective method to realize a waveguide structure with superior optical properties. The sample is implanted by C ions at energy of 5.0 MeV with the fluence of 1 × 1015 ions/cm2. We researched the optical propagation properties in the Nd:YGG waveguide by end-face coupling and prism coupling method. The Nd ions fluorescent properties are obtained by a confocal micro-luminescence measurement. The fluorescent properties of Nd ions obtained good reservation after C ion implantation. Our work has reference value for the application of Nd:YGG crystal in the field of optical communication.

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.

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.

Multi-Wavelength Mode-Locked Laser Arrays for WDM Applications

NASA Technical Reports Server (NTRS)

Davis, L.; Young, M.; Dougherty, D.; Keo, S.; Muller, R.; Maker, P.

1998-01-01

Multi-wavelength arrays of colliding pulse mode-locked (CPM) lasers have been demonstrated for wavelength division multiplexing (WDM) applications. The need for increased bandwidth is driving the development of both increased speed in time division multiplexing (TDM) and more channels in WDM for fiber optic communication systems.

Adaptive laser link reconfiguration using constraint propagation

NASA Technical Reports Server (NTRS)

Crone, M. S.; Julich, P. M.; Cook, L. M.

1993-01-01

This paper describes Harris AI research performed on the Adaptive Link Reconfiguration (ALR) study for Rome Lab, and focuses on the application of constraint propagation to the problem of link reconfiguration for the proposed space based Strategic Defense System (SDS) Brilliant Pebbles (BP) communications system. According to the concept of operations at the time of the study, laser communications will exist between BP's and to ground entry points. Long-term links typical of RF transmission will not exist. This study addressed an initial implementation of BP's based on the Global Protection Against Limited Strikes (GPALS) SDI mission. The number of satellites and rings studied was representative of this problem. An orbital dynamics program was used to generate line-of-site data for the modeled architecture. This was input into a discrete event simulation implemented in the Harris developed COnstraint Propagation Expert System (COPES) Shell, developed initially on the Rome Lab BM/C3 study. Using a model of the network and several heuristics, the COPES shell was used to develop the Heuristic Adaptive Link Ordering (HALO) Algorithm to rank and order potential laser links according to probability of communication. A reduced set of links based on this ranking would then be used by a routing algorithm to select the next hop. This paper includes an overview of Constraint Propagation as an Artificial Intelligence technique and its embodiment in the COPES shell. It describes the design and implementation of both the simulation of the GPALS BP network and the HALO algorithm in COPES. This is described using a 59 Data Flow Diagram, State Transition Diagrams, and Structured English PDL. It describes a laser communications model and the heuristics involved in rank-ordering the potential communication links. The generation of simulation data is described along with its interface via COPES to the Harris developed View Net graphical tool for visual analysis of communications networks. Conclusions are presented, including a graphical analysis of results depicting the ordered set of links versus the set of all possible links based on the computed Bit Error Rate (BER). Finally, future research is discussed which includes enhancements to the HALO algorithm, network simulation, and the addition of an intelligent routing algorithm for BP.

Realization of pure frequency modulation of DFB laser via combined optical and electrical tuning.

PubMed

Tian, Chao; Chen, I-Chun Anderson; Park, Seong-Wook; Martini, Rainer

2013-04-08

In this paper we present a novel approach to convert AM signal into FM signal in semiconductor lasers via off resonance optical pumping and report on experimental results obtained with a commercial DFB laser. Aside of demonstrating discrete and fast frequency modulation, we achieve pure frequency modulation through combination with electrical modulation suppressing the associated amplitude modulation, which is detrimental to application such as spectroscopy and communication.

50 Mb/s, 220-mW Laser-Array Transmitter

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.

1992-01-01

Laser transmitter based on injection locking produces single-wavelength, diffraction-limited, single-lobe beam. Output stage is array of laser diodes producing non-diffraction-limited, multi-mode beam in absence of injection locking. Suitable for both free-space and optical-fiber communication systems. Because beam from transmitter focused to spot as small as 5 micrometers, devices usable for reading and writing optical disks at increased information densities. Application also in remote sensing and ranging.

BRIEF COMMUNICATIONS: Experimental study of the energy balance in the interaction of a pulsed CO2 laser with metal and insulating targets in air

NASA Astrophysics Data System (ADS)

Babaeva, N. A.; Vas'kovskiĭ, Yu M.; Rovinskiĭ, R. E.; Ryabinkina, V. A.

1991-09-01

Measurements were made of components of the energy balance in the interaction of pulsed CO2 laser radiation with Dural, glass, quartz, ebonite, and Plexiglas in air at atmospheric pressure. At laser energy densities between 1 and 20 J/cm2 and in the spectral range 0.2-7 μm, the re-emission of radiation by the laser plasma was found to be less than 1 %. At energy densities exceeding 10 J/cm2, up to 90% of the laser energy failed to reach the irradiated surface.

High-power AlGaAs channeled substrate planar diode lasers for spaceborne communications

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Goldstein, B.; Pultz, G. N.; Slavin, S. E.; Carlin, D. B.; Ettenberg, M.

1988-01-01

A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described.

Ad hoc Laser networks component technology for modular spacecraft

NASA Astrophysics Data System (ADS)

Huang, Xiujun; Shi, Dele; Ma, Zongfeng; Shen, Jingshi

2016-03-01

Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

Ad hoc laser networks component technology for modular spacecraft

NASA Astrophysics Data System (ADS)

Huang, Xiujun; Shi, Dele; Shen, Jingshi

2017-10-01

Distributed reconfigurable satellite is a new kind of spacecraft system, which is based on a flexible platform of modularization and standardization. Based on the module data flow analysis of the spacecraft, this paper proposes a network component of ad hoc Laser networks architecture. Low speed control network with high speed load network of Microwave-Laser communication mode, no mesh network mode, to improve the flexibility of the network. Ad hoc Laser networks component technology was developed, and carried out the related performance testing and experiment. The results showed that ad hoc Laser networks components can meet the demand of future networking between the module of spacecraft.

Tri-channel single-mode terahertz quantum cascade laser.

PubMed

Wang, Tao; Liu, Jun-Qi; Liu, Feng-Qi; Wang, Li-Jun; Zhang, Jin-Chuan; Wang, Zhan-Guo

2014-12-01

We report on a compact THz quantum cascade laser source emitting at, individually controllable, three different wavelengths (92.6, 93.9, and 95.1 μm). This multiwavelength laser array can be used as a prototype of the emission source of THz wavelength division multiplex (WDM) wireless communication system. The source consists of three tapered single-mode distributed feedback (DFB) terahertz quantum cascade lasers fabricated monolithically on a single chip. All array elements feature longitudinal as well as lateral single-mode in the entire injection range. The peak output powers of individual lasers are 42, 73, and 37 mW at 10 K, respectively.

Carbon-assisted flyer plates

DOEpatents

Stahl, D.B.; Paisley, D.L.

1994-04-12

A laser driven flyer plate is described utilizing an optical fiber connected to a laser. The end of the optical fiber has a layer of carbon and a metal layer deposited onto it. The carbon layer provides the laser induced plasma which is superior to the plasma produced from most metals. The carbon layer plasma is capable of providing a flatter flyer plate, converting more of the laser energy to driving plasma, promoting a higher flyer plate acceleration, and providing a more uniform pulse behind the plate. In another embodiment, the laser is in optical communication with a substrate onto which a layer of carbon and a layer of metal have been deposited. 2 figures.

Precision Laser Development for Gravitational Wave Space Mission

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2011-01-01

Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, such as the gravitational-wave mission LISA, and GRACE follow-on, by fully utilizing the mature wave-guided optics technologies. In space, where a simple and reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Non-planar Ring Oscillator) and bulk-crystal amplifier, which are widely used for sensitive laser applications on the ground.

Research on the system performance evaluation of minimum-shift keying in uplink ground-to-satellite with gamma-gamma distribution

NASA Astrophysics Data System (ADS)

Wang, Yi; Zhang, Ao; Ma, Jing

2017-07-01

Minimum-shift keying (MSK) has the advantages of constant envelope, continuous phase, and high spectral efficiency, and it is applied in radio communication and optical fiber communication. MSK modulation of coherent detection is proposed in the ground-to-satellite laser communication system; in addition, considering the inherent noise of uplink, such as intensity scintillation and beam wander, the communication performance of the MSK modulation system with coherent detection is studied in the uplink ground-to-satellite laser. Based on the gamma-gamma channel model, the closed form of bit error rate (BER) of MSK modulation with coherent detection is derived. In weak, medium, and strong turbulence, the BER performance of the MSK modulation system is simulated and analyzed. To meet the requirements of the ground-to-satellite coherent MSK system to optimize the parameters and configuration of the transmitter and receiver, the influence of the beam divergence angle, the zenith angle, the transmitter beam radius, and the receiver diameter are studied.

Laser Ranging in Solar System: Technology Developments and New Science Measurement Capabilities

NASA Astrophysics Data System (ADS)

Sun, X.; Smith, D. E.; Zuber, M. T.; Mcgarry, J.; Neumann, G. A.; Mazarico, E.

2015-12-01

Laser Ranging has played a major role in geodetic studies of the Earth over the past 40 years. The technique can potentially be used in between planets and spacecrafts within the solar system to advance planetary science. For example, a direct measurement of distances between planets, such as Mars and Venus would make significant improvements in understanding the dynamics of the whole solar system, including the masses of the planets and moons, asteroids and their perturbing interactions, and the gravity field of the Sun. Compared to the conventional radio frequency (RF) tracking systems, laser ranging is potentially more accurate because it is much less sensitive to the transmission media. It is also more efficient because the laser beams are much better focused onto the targets than RF beams. However, existing laser ranging systems are all Earth centric, that is, from ground stations on Earth to orbiting satellites in near Earth orbits or lunar orbit, and to the lunar retro-reflector arrays deployed by the astronauts in the early days of lunar explorations. Several long distance laser ranging experiments have been conducted with the lidar in space, including a two-way laser ranging demonstration between Earth and the Mercury Laser Altimeter (MLA) on the MESSENGER spacecraft over 24 million km, and a one way laser transmission and detection experiment over 80 million km between Earth and the Mars Orbiting Laser Altimeter (MOLA) on the MGS spacecraft in Mars orbit. A one-way laser ranging operation has been carried out continuously from 2009 to 2014 between multiple ground stations to LRO spacecraft in lunar orbit. The Lunar Laser Communication Demonstration (LLCD) on the LADEE mission has demonstrated that a two way laser ranging measurements, including both the Doppler frequency and the phase shift, can be obtained from the subcarrier or the data clocks of a high speed duplex laser communication system. Plans and concepts presently being studied suggest we may be on the cusp of demonstrating interplanetary laser ranging to bring the future of solar system geodesy and geodyamics into reality.

Micro-laser

DOEpatents

Hutchinson, Donald P.; Richards, Roger K.

2003-07-22

A micro-laser is disclosed which includes a waveguide, a first and a second subwavelength resonant grating in the waveguide, and at least one photonic band gap resonant structure (PBG) in the waveguide and at least one amplifying medium in the waveguide. PBG features are positioned between the first and second subwavelength resonant gratings and allow introduction of amplifying mediums into the highly resonant guided micro-laser microcavity. The micro-laser may be positioned on a die of a bulk substrate material with one or more electronic and optical devices and may be communicably connected to the same. A method for fabricating a micro-laser is disclosed. A method for tuning the micro-laser is also disclosed. The micro-laser may be used as an optical regenerator, or a light source for data transfer or for optical computing.

Optical Phased Array Antennas using Coupled Vertical Cavity Surface Emitting Lasers

NASA Technical Reports Server (NTRS)

Mueller, Carl H.; Rojas, Roberto A.; Nessel, James A.; Miranda, Felix A.

2007-01-01

High data rate communication links are needed to meet the needs of NASA as well as other organizations to develop space-based optical communication systems. These systems must be robust to high radiation environments, reliable, and operate over a wide temperature range. Highly desirable features include beam steering capability, reconfigurability, low power consumption, and small aperture size. Optical communication links, using coupled vertical cavity surface emitting laser radiating elements are promising candidates for the transmit portion of these communication links. In this talk we describe a mission scenario, and how the antenna requirements are derived from the mission needs. We describe a potential architecture for this type of antenna, and outline the advantages and drawbacks of this approach relative to competing technologies. The technology we are proposing used coupled arrays of 1550 nm vertical cavity surface emitting lasers for transmission. The feasibility of coupling these arrays together, to form coherent high-power beams that can be modulated at data rates exceeding 1 Gbps, will be explored. We will propose an architecture that enables electronic beam steering, thus mitigating the need for ancillary acquisition, tracking and beam pointing equipment such as needed for current optical communicatin systems. The beam-steering capability we are proposing also opens the possibility of using this technology for inter-satellite communicatin links, and satellite-to-surface links.

Application of spinal code for performance improvement in free-space optical communications

NASA Astrophysics Data System (ADS)

Saiki, Naoya; Okamoto, Eiji; Takenaka, Hideki; Toyoshima, Morio

2017-09-01

In recent years, the demand for high-capacity communication has grown, and fiber-optic transmission is being used in wired communications to meet this demand. Similarly, free-space optics (FSO), which is an optical wireless communication technology that uses laser light, has attracted much attention and has been considered as a suitable alternative to satisfy this demand in wireless communications. Free-space optical communication uses a hundred THz frequency band and allows for high-speed and radio-regulation free transmission, which may provide a solution for the current shortage of radio frequency bands.

Faithful communication Hamiltonian in photonic lattices

NASA Astrophysics Data System (ADS)

Bellec, Matthieu; Nikolopoulos, Georgios M.; Tzortzakis, Stelios

2012-11-01

Faithful communication is a necessary precondition for large scale all-optical networking and quantum information processing. Related theoretical investigations in different areas of physics have led to various proposals in which finite discrete lattices are used as channels for short-distance communication tasks. Here, in the framework of femtosecond-laser-written waveguide arrays, we present the first experimental realization of such a channel with judiciously engineered couplings.

Polarization tracking system for free-space optical communication, including quantum communication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nordholt, Jane Elizabeth; Newell, Raymond Thorson; Peterson, Charles Glen

Quantum communication transmitters include beacon lasers that transmit a beacon optical signal in a predetermined state of polarization such as one of the states of polarization of a quantum communication basis. Changes in the beacon polarization are detected at a receiver, and a retarder is adjusted so that the states of polarization in a received quantum communication optical signal are matched to basis polarizations. The beacon and QC signals can be at different wavelengths so that the beacon does not interfere with detection and decoding of the QC optical signal.

Spin-controlled ultrafast vertical-cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Höpfner, Henning; Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.

2014-05-01

Spin-controlled semiconductor lasers are highly attractive spintronic devices providing characteristics superior to their conventional purely charge-based counterparts. In particular, spin-controlled vertical-cavity surface emitting lasers (spin-VCSELs) promise to offer lower thresholds, enhanced emission intensity, spin amplification, full polarization control, chirp control and ultrafast dynamics. Most important, the ability to control and modulate the polarization state of the laser emission with extraordinarily high frequencies is very attractive for many applications like broadband optical communication and ultrafast optical switches. We present a novel concept for ultrafast spin-VCSELs which has the potential to overcome the conventional speed limitation for directly modulated lasers by the relaxation oscillation frequency and to reach modulation frequencies significantly above 100 GHz. The concept is based on the coupled spin-photon dynamics in birefringent micro-cavity lasers. By injecting spin-polarized carriers in the VCSEL, oscillations of the coupled spin-photon system can by induced which lead to oscillations of the polarization state of the laser emission. These oscillations are decoupled from conventional relaxation oscillations of the carrier-photon system and can be much faster than these. Utilizing these polarization oscillations is thus a very promising approach to develop ultrafast spin-VCSELs for high speed optical data communication in the near future. Different aspects of the spin and polarization dynamics, its connection to birefringence and bistability in the cavity, controlled switching of the oscillations, and the limitations of this novel approach will be analysed theoretically and experimentally for spin-polarized VCSELs at room temperature.

Eruptive keratoacanthomas following carbon dioxide laser resurfacing.

PubMed

Gewirtzman, A; Meirson, D H; Rabinovitz, H

1999-08-01

Skin resurfacing with the carbon dioxide (CO2) laser is currently a popular means of improving rhytides and scars. Scarring, hyperpigmentation, hypopigmentation, and infection are among the complications that have been known to occur in some patients treated with the CO2 laser. We wish to communicate a previously unreported complication of CO2 laser resurfacing-multiple eruptive keratoacanthomas. We describe a 61-year-old woman who presented with multiple eruptive keratoacanthomas subsequent to CO2 laser resurfacing. Her lesions were cultured for fungus and bacteria. Biopsy specimens of two lesions were taken. Cultures were negative for pathogens. Biopsy specimens revealed atypical squamous epithelial proliferation and changes consistent with eruptive keratoacanthomas. Multiple eruptive keratoacanthomas should be considered as a rare complication of CO2 laser resurfacing.

Probabilistic Risk Assessment Process for High-Power Laser Operations in Outdoor Environments

DTIC Science & Technology

2016-01-01

avionics data bus. In the case of a UAS-mounted laser system, the control path will additionally include a radio or satellite communications link. A remote...JBSA Fort Sam Houston, TX 78234 711 HPW/RHDO 11 . SPONSOR’S/MONITOR’S REPORT NUMBER(S) AFRL-RH-FS-JA-2015...hazard assessment pur- poses is not widespread within the laser safety community . The aim of this paper is to outline the basis of the probabilistic

Link Performance Analysis of a Ship-to-Ship Laser Communication System

DTIC Science & Technology

2012-03-01

the optical output by a modulating signal. Direct detection requires only the intensity, and not the phase information, of the input signal to...links have a higher signal-to-noise ratio ( ) as compared to RF link. However, at approximately 108 km, the SNR for the optical links is much... optical signal received is mixed with a light signal generated from a local oscillator laser (LO-laser). The combined signals are then impinged onto the

Engineering planetary lasers for interstellar communication. M.S. Thesis

NASA Technical Reports Server (NTRS)

Sherwood, Brent

1988-01-01

Transmitting large amounts of data efficiently among neighboring stars will vitally support any eventual contact with extrasolar intelligence, whether alien or human. Laser carriers are particularly suitable for high-quality, targeted links. Space laser transmitter systems designed by this work, based on both demonstrated and imminent advanced space technology, could achieve reliable data transfer rates as high as 1 kb/s to matched receivers as far away as 25 pc, a distance including over 700 approximately solar-type stars. The centerpiece of this demonstration study is a fleet of automated spacecraft incorporating adaptive neural-net optical processing active structures, nuclear electric power plants, annular momentum control devices, and ion propulsion. Together the craft sustain, condition, modulate, and direct to stellar targets an infrared laser beam extracted from the natural mesospheric, solar-pumped, stimulated CO2 emission recently discovered at Venus. For a culture already supported by mature interplanetary industry, the cost of building planetary or high-power space laser systems for interstellar communication would be marginal, making such projects relevant for the next human century. Links using high-power lasers might support data transfer rates as high as optical frequencies could ever allow. A nanotechnological society such as we might become would inevitably use 10 to the 20th power b/yr transmission to promote its own evolutionary expansion out of the galaxy.

Multiple wavelength spectral system simulating background light noise environment in satellite laser communications

NASA Astrophysics Data System (ADS)

Lu, Wei; Sun, Jianfeng; Hou, Peipei; Xu, Qian; Xi, Yueli; Zhou, Yu; Zhu, Funan; Liu, Liren

2017-08-01

Performance of satellite laser communications between GEO and LEO satellites can be influenced by background light noise appeared in the field of view due to sunlight or planets and some comets. Such influences should be studied on the ground testing platform before the space application. In this paper, we introduce a simulator that can simulate the real case of background light noise in space environment during the data talking via laser beam between two lonely satellites. This simulator can not only simulate the effect of multi-wavelength spectrum, but also the effects of adjustable angles of field-of-view, large range of adjustable optical power and adjustable deflection speeds of light noise in space environment. We integrate these functions into a device with small and compact size for easily mobile use. Software control function is also achieved via personal computer to adjust these functions arbitrarily. Keywords:

Why Aren’t Lightsabers Real Yet? Get the Lowdown from a Laser Physicist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunsberger, Maren; Liao, Zhi

The release of "Star Wars: The Force Awakens" begs the obvious question: Why aren't lightsabers real yet? LLNL science communicator Maren Hunsberger gets the lowdown from laser physicist Zhi Liao in this first installment of "Inside the Lab," a new YouTube series exploring crazy-cool science questions.

Gigabit-per-second white light-based visible light communication using near-ultraviolet laser diode and red-, green-, and blue-emitting phosphors.

PubMed

Lee, Changmin; Shen, Chao; Cozzan, Clayton; Farrell, Robert M; Speck, James S; Nakamura, Shuji; Ooi, Boon S; DenBaars, Steven P

2017-07-24

Data communication based on white light generated using a near-ultraviolet (NUV) laser diode (LD) pumping red-, green-, and blue-emitting (RGB) phosphors was demonstrated for the first time. A III-nitride laser diode (LD) on a semipolar (2021¯)  substrate emitting at 410 nm was used for the transmitter. The measured modulation bandwidth of the LD was 1 GHz, which was limited by the avalanche photodetector. The emission from the NUV LD and the RGB phosphor combination measured a color rendering index (CRI) of 79 and correlated color temperature (CCT) of 4050 K, indicating promise of this approach for creating high quality white lighting. Using this configuration, data was successfully transmitted at a rate of more than 1 Gbps. This NUV laser-based system is expected to have lower background noise from sunlight at the LD emission wavelength than a system that uses a blue LD due to the rapid fall off in intensity of the solar spectrum in the NUV spectral region.

3D laser scanning and modelling of the Dhow heritage for the Qatar National Museum

NASA Astrophysics Data System (ADS)

Wetherelt, A.; Cooper, J. P.; Zazzaro, C.

2014-08-01

Curating boats can be difficult. They are complex structures, often demanding to conserve whether in or out of the water; they are usually large, difficult to move on land, and demanding of gallery space. Communicating life on board to a visiting public in the terra firma context of a museum can be difficult. Boats in their native environment are inherently dynamic artifacts. In a museum they can be static and divorced from the maritime context that might inspire engagement. New technologies offer new approaches to these problems. 3D laser scanning and digital modeling offers museums a multifaceted means of recording, monitoring, studying and communicating watercraft in their care. In this paper we describe the application of 3D laser scanning and subsequent digital modeling. Laser scans were further developed using computer-generated imagery (CGI) modeling techniques to produce photorealistic 3D digital models for development into interactive, media-based museum displays. The scans were also used to generate 2D naval lines and orthographic drawings as a lasting curatorial record of the dhows held by the National Museum of Qatar.

Atmospheric-Fade-Tolerant Tracking and Pointing in Wireless Optical Communication

NASA Technical Reports Server (NTRS)

Ortiz, Gerardo; Lee, Shinhak

2003-01-01

An acquisition, tracking, and pointing (ATP) system, under development at the time of reporting the information for this article, is intended to enable a terminal in a free-space optical communication system to continue to aim its transmitting laser beam toward a receiver at a remote terminal when the laser beacon signal from the remote terminal temporarily fades or drops out of sight altogether. Such fades and dropouts can be caused by adverse atmospheric conditions (e.g., rain or clouds). They can also occur when intervening objects block the line of sight between terminals as a result of motions of those objects or of either or both terminals

Numerical aperture limits on efficient ball lens coupling of laser diodes to single-mode fibers with defocus to balance spherical aberration

NASA Technical Reports Server (NTRS)

Wilson, R. Gale

1994-01-01

The potential capabilities and limitations of single ball lenses for coupling laser diode radiation to single-mode optical fibers have been analyzed; parameters important to optical communications were specifically considered. These parameters included coupling efficiency, effective numerical apertures, lens radius, lens refractive index, wavelength, magnification in imaging the laser diode on the fiber, and defocus to counterbalance spherical aberration of the lens. Limiting numerical apertures in object and image space were determined under the constraint that the lens perform to the Rayleigh criterion of 0.25-wavelength (Strehl ratio = 0.80). The spherical aberration-defocus balance to provide an optical path difference of 0.25 wavelength units was shown to define a constant coupling efficiency (i.e., 0.56). The relative numerical aperture capabilities of the ball lens were determined for a set of wavelengths and associated fiber-core diameters of particular interest for single-mode fiber-optic communication. The results support general continuing efforts in the optical fiber communications industry to improve coupling links within such systems with emphasis on manufacturing simplicity, system packaging flexibility, relaxation of assembly alignment tolerances, cost reduction of opto-electronic components and long term reliability and stability.

A Modular Control Platform for a Diode Pumped Alkali Laser

NASA Astrophysics Data System (ADS)

Shapiro, J.; Teare, S.

Many of the difficulties of creating compact, high power laser systems can be overcome if the heat dissipating properties of chemical lasers can be combined with the efficiency of diode lasers. Recently, the novel idea of using solid state diode lasers to pump gaseous gain media, such as is done in diode pumped alkali lasers (DPALs), has been proposed and early experiments have shown promising results. However, a number of technical issues need to be overcome to realize high output power from these lasers. In order to achieve higher power, the efficiency of coupling between pump laser energy and the chemical cell must be increased, and eventually multiple high power diode pumps must be combined and synchronized so that their energy can pump the chemical cell. Additionally, an inter-cavity adaptive optics system may be a requirement to be able to propagate these lasers with high efficiency. DPAL systems are complex and require a significant amount of data fusion and active feedback to control and optimize their performance. There are a wide range of components including pump lasers, gain cells and monitoring points needed to study and refine the overall laser system. In support of this dynamic development environment, we have developed a hardware framework using commercial off the shelf (COTS) components which supports the rapid assembly of functional system blocks into a cohesive integrated system. Critical to this system are a simple communication protocol, industry standard communication pipes (USB, Bluetooth, etc), and flexible high level scripting. Simplifying the integration process has the benefit of allowing flexible "on the fly" modifications to adapt the system as needed and enhance available functionality. The modular nature of the architecture allows scalability and adaptability as more pieces are added to the system. Key components of this system are demonstrated for selected portions of a DPAL system using a USB backbone.

Reduction of degradation in vapor phase transported InP/InGaAsP mushroom stripe lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, H.; Burkhardt, E.G.; Pfister, W.

1988-10-03

The rapid degradation rate generally observed in InP/InGaAsP mushroom stripe lasers can be considerably decreased by regrowing the open sidewalls of the active stripe with low-doped InP in a second epitaxial step using the hydride vapor phase transport technique. This technique does not change the fundamental laser parameters like light-current and current-voltage characteristics. Because of this drastic reduction in degradation, the vapor phase epitaxy regrown InP/InGaAsP mushroom laser seems to be an interesting candidate for application in optical communication.

Aircraft Detection System Ensures Free-Space Laser Safety

NASA Technical Reports Server (NTRS)

Smithgall, Brian; Wilson, Keith E.

2004-01-01

As scientists continue to explore our solar system, there are increasing demands to return greater volumes of data from smaller deep-space probes. Accordingly, NASA is studying advanced strategies based on free-space laser transmissions, which offer secure, high-bandwidth communications using smaller subsystems of much lower power and mass than existing ones. These approaches, however, can pose a danger to pilots in the beam path because the lasers may illuminate aircraft and blind them. Researchers thus are investigating systems that will monitor the surrounding airspace for aircraft that could be affected. This paper presents current methods for safe free space laser propagation.

A low-threshold, high-efficiency microfluidic waveguide laser.

PubMed

Vezenov, Dmitri V; Mayers, Brian T; Conroy, Richard S; Whitesides, George M; Snee, Preston T; Chan, Yinthai; Nocera, Daniel G; Bawendi, Moungi G

2005-06-29

This communication describes a long (1 cm), laser-pumped, liquid core-liquid cladding (L2) waveguide laser. This device provides a simple, high intensity, tunable light source for microfludic applications. Using a core solution of 2 mM rhodamine 640 perchlorate, optically pumped by a frequency-doubled Nd:YAG laser, we found that the threshold for lasing was as low as 22 muJ (16-ns pulse length) and had a slope efficiency up to 20%. The output wavelength was tunable over a 20-nm range by changing the ratio of solvent components (dimethyl sulfoxide and methanol) in the liquid core.

Femtosecond Laser--Pumped Source of Entangled Photons for Quantum Cryptography Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, D.; Donaldson, W.; Sobolewski, R.

2007-07-31

We present an experimental setup for generation of entangled-photon pairs via spontaneous parametric down-conversion, based on the femtosecond-pulsed laser. Our entangled-photon source utilizes a 76-MHz-repetition-rate, 100-fs-pulse-width, mode-locked, ultrafast femtosecond laser, which can produce, on average, more photon pairs than a cw laser of an equal pump power. The resulting entangled pairs are counted by a pair of high-quantum-efficiency, single-photon, silicon avalanche photodiodes. Our apparatus is intended as an efficient source/receiver system for the quantum communications and quantum cryptography applications.

Precision Laser Development for Interferometric Space Missions NGO, SGO, and GRACE Follow-On

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2011-01-01

Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, including the gravitational-wave missions NGO/SGO (formerly LISA) and the climate monitoring mission GRACE Follow-On, by fully utilizing the matured wave-guided optics technologies. In space, where simpler and more reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Nonplanar Ring Oscillator) and bulk-crystal amplifier.

NASA Hitchhiker Program Customer Payload Requirements (CPR)

NASA Technical Reports Server (NTRS)

Horan, Stephen

1998-01-01

The mission objective is to demonstrate each of the three types of technology intended for future small-satellite communications system design. Each experiment in the overall package is designed to exercise a different technology objective that may be found in the overall satellite communications and telemetry system design. The data communications through TORSS portion is designed to demonstrate that low-power communications systems with non-gimbaled antenna systems can transport significant quantities of data through TDRSS to the ground based on only transmitting through a TDRS when the experiment is near the TDRS subsatellite point. The remaining time. the payload communications system is not active. The demand access experiment is to demonstrate that the request for a demand access service can be transmitted through TDRS and received and decoded at the ground station. In this mode, the TDRS does not track the experiment but signal processing components at the White Sands Complex are used to detect and track the transmitted request. The laser communications experiment is designed to demonstrate passive transmission of telemetry data from the experiment. This mode uses a ground-based laser source to illuminate the experiment and modulate the beam with the data. Ground-based reception recovers the data from the reflected beam back to the ground station.

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.

Wavelength-versatile optical vortex lasers

NASA Astrophysics Data System (ADS)

Omatsu, Takashige; Miyamoto, Katsuhiko; Lee, Andrew J.

2017-12-01

The unique properties of optical vortex beams, in particular their spiral wavefront, have resulted in the emergence of a wide range of unique applications for this type of laser output. These applications include optical tweezing, free space optical communications, microfabrication, environmental optics, and astrophysics. However, much like the laser in its infancy, the adaptation of this type of laser output requires a diversity of wavelengths. We report on recent progress on development of optical vortex laser sources and in particular, focus on their wavelength extension, where nonlinear optical processes have been used to generate vortex laser beams with wavelengths which span the ultraviolet to infrared. We show that nonlinear optical conversion can be used to not only diversify the output wavelength of these sources, but can be used to uniquely engineer the wavefront and spatial properties of the laser output.

Telecom-Wavelength Bottom-up Nanobeam Lasers on Silicon-on-Insulator.

PubMed

Kim, Hyunseok; Lee, Wook-Jae; Farrell, Alan C; Balgarkashi, Akshay; Huffaker, Diana L

2017-09-13

Semiconductor nanowire lasers are considered promising ultracompact and energy-efficient light sources in the field of nanophotonics. Although the integration of nanowire lasers onto silicon photonic platforms is an innovative path toward chip-scale optical communications and photonic integrated circuits, operating nanowire lasers at telecom-wavelengths remains challenging. Here, we report on InGaAs nanowire array lasers on a silicon-on-insulator platform operating up to 1440 nm at room temperature. Bottom-up photonic crystal nanobeam cavities are formed by growing nanowires as ordered arrays using selective-area epitaxy, and single-mode lasing by optical pumping is demonstrated. We also show that arrays of nanobeam lasers with individually tunable wavelengths can be integrated on a single chip by the simple adjustment of the lithographically defined growth pattern. These results exemplify a practical approach toward nanowire lasers for silicon photonics.

Hybrid III-V/silicon lasers

NASA Astrophysics Data System (ADS)

Kaspar, P.; Jany, C.; Le Liepvre, A.; Accard, A.; Lamponi, M.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Shen, A.; Charbonnier, P.; Mallecot, F.; Duan, G.-H.; Gentner, J.-.; Fedeli, J.-M.; Olivier, S.; Descos, A.; Ben Bakir, B.; Messaoudene, S.; Bordel, D.; Malhouitre, S.; Kopp, C.; Menezo, S.

2014-05-01

The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.

Communications technology

NASA Astrophysics Data System (ADS)

Sokoloski, Martin M.

1988-09-01

The objective of the Communications Technology Program is to enable data transmission to and from low Earth orbit, geostationary orbit, and solar and deep space missions. This can be achieved by maintaining an effective, balances effort in basic, applied, and demonstration prototype communications technology through work in theory, experimentation, and components. The program consists of three major research and development discipline areas which are: microwave and millimeter wave tube components; solid state monolithic integrated circuit; and free space laser communications components and devices. The research ranges from basic research in surface physics (to study the mechanisms of surface degradation from under high temperature and voltage operating conditions which impacts cathode tube reliability and lifetime) to generic research on the dynamics of electron beams and circuits (for exploitation in various micro- and millimeter wave tube devices). Work is also performed on advanced III-V semiconductor materials and devices for use in monolithic integrated analog circuits (used in adaptive, programmable phased arrays for microwave antenna feeds and receivers) - on the use of electromagnetic theory in antennas and on technology necessary for eventual employment of lasers for free space communications for future low earth, geostationary, and deep space missions requiring high data rates with corresponding directivity and reliability.

Communications technology

NASA Technical Reports Server (NTRS)

Sokoloski, Martin M.

1988-01-01

The objective of the Communications Technology Program is to enable data transmission to and from low Earth orbit, geostationary orbit, and solar and deep space missions. This can be achieved by maintaining an effective, balances effort in basic, applied, and demonstration prototype communications technology through work in theory, experimentation, and components. The program consists of three major research and development discipline areas which are: microwave and millimeter wave tube components; solid state monolithic integrated circuit; and free space laser communications components and devices. The research ranges from basic research in surface physics (to study the mechanisms of surface degradation from under high temperature and voltage operating conditions which impacts cathode tube reliability and lifetime) to generic research on the dynamics of electron beams and circuits (for exploitation in various micro- and millimeter wave tube devices). Work is also performed on advanced III-V semiconductor materials and devices for use in monolithic integrated analog circuits (used in adaptive, programmable phased arrays for microwave antenna feeds and receivers) - on the use of electromagnetic theory in antennas and on technology necessary for eventual employment of lasers for free space communications for future low earth, geostationary, and deep space missions requiring high data rates with corresponding directivity and reliability.

Brief communication: sliding displacement of amnion and chorion following controlled laser wounding suggests a mechanism for short-term sealing of ruptured membranes.

PubMed

Behzad, F; Dickinson, M R; Charlton, A; Aplin, J D

1994-10-01

The Erbium-YAG laser was used to produce narrow wounds of defined depth in term amniochorion. The charring effect of the laser meant that sites could be readily localized in histological sections. During brief post-wounding incubations, sliding displacement of the amnion relative to the chorion occurred through the plane of the spongy layer. This suggests a possible short-term mechanism whereby a spontaneous rupture could be sealed in vivo.

Widely tunable Tm-doped mode-locked all-fiber laser

PubMed Central

Yan, Zhiyu; Sun, Biao; Li, Xiaohui; Luo, Jiaqi; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie

2016-01-01

We demonstrated a widely tunable Tm-doped mode-locked all-fiber laser, with the widest tunable range of 136 nm, from 1842 to 1978 nm. Nonlinear polarization evolution (NPE) technique is employed to enable mode-locking and the wavelength-tunable operation. The widely tunable range attributes to the NPE-induced transmission modulation and bidirectional pumping mechanism. Such kind of tunable mode-locked laser can find various applications in optical communications, spectroscopy, time-resolved measurement, and among others. PMID:27263655

Evaluation results for the positive deep-UV resist AZ DX 46

NASA Astrophysics Data System (ADS)

Spiess, Walter; Lynch, Thomas J.; Le Cornec, Charles; Escher, Gary C.; Kinoshita, Yoshiaki; Kochan, John; Kudo, Takanori; Masuda, Seiya; Mourier, Thierry; Nozaki, Yuko; Olson, Setha G.; Okazaki, Hiroshi; Padmanaban, Munirathna; Pawlowski, Georg; Przybilla, Klaus J.; Roeschert, Horst; Suehiro, Natusmi; Vinet, Francoise; Wengenroth, Horst

1994-05-01

This contribution emphasizes resist application site by communicating lithographic results for AZ DX 46, obtained using the GCA XLS 7800/31 stepper, NA equals 0.53, equipped with krypton fluoride excimer laser ((lambda) equals 248 nm), model 4500 D, as exposure source, delivered by Cymer Laser Technologies. As far as delay time experiments are concerned ASM-L PAS 5500/70 stepper, NA equals 0.42, was used in combination with Lambda Physik excimer laser, model 248 L.

Strong Optical Injection Locking of Edge-Emitting Lasers and Its Applications

DTIC Science & Technology

2006-08-18

investigated for communications applications. Using AlGaAs lasers, Kobayashi et al. demonstrated stable single-mode operation of Fabry - Perot (F-P...modulation (AM) efficiency is obtained at the expense of linearity. Furthermore, the previous gain-lever devices were Fabry - Perot (F-P) lasers operating in...coating of ~ 0.2-μm Zirconium dioxide (ZrO2) layer with a reflectivity of less than 0.1% is deposited on one facet to suppress the Fabry - Perot (F-P

Communication: Strong laser alignment of solvent-solute aggregates in the gas-phase

NASA Astrophysics Data System (ADS)

Trippel, Sebastian; Wiese, Joss; Mullins, Terry; Küpper, Jochen

2018-03-01

Strong quasi-adiabatic laser alignment of the indole-water-dimer clusters, an amino-acid chromophore bound to a single water molecule through a hydrogen bond, was experimentally realized. The alignment was visualized through ion and electron imaging following strong-field ionization. Molecular-frame photoelectron angular distributions showed a clear suppression of the electron yield in the plane of the ionizing laser's polarization, which was analyzed as strong alignment of the molecular cluster with ⟨cos2 θ2D⟩ ≥ 0.9.

Optical superheterodyne receiver.

NASA Technical Reports Server (NTRS)

Duval, K.; Lang, K.; Lucy, R. F.; Peters, C. J.

1967-01-01

Optical communication experiments to compare coherent and noncoherent optical detection fading characteristics in different weather conditions, using laser transmitter and optical superheterodyne receiver

Intentionally Short-Range Communications (ISRC)

NASA Astrophysics Data System (ADS)

Yen, J.; Poirier, P.; Obrien, M.

1994-02-01

The U.S. Marine Corps (USMC) desired to develop short-range communications links whose ranges are intentionally limited to very short distances. These links support tactical missions such as LAN Backbone, Wideband Data Link, and Company Radio. The short-range limitation arises from the need for low probability of detection and intercept (LPD/LPI). Since the detection of an undecipherable transmission would still provide an enemy with information regarding transmitter location and allow him to take countermeasures, the Marine Corps Systems Command (MARCORSYSCOM) is sponsoring the development of technologies that can be LPD by their very nature. The Intentionally Short-Range Communications (ISRC) project at the Naval Command, Control and Ocean Surveillance Center (NCCOSC) RDT&E Division (NRaD) is pursuing feasibility studies for these USMC missions based on such technologies as ultraviolet (LTV) lamps, UV lasers, infrared (IR) lasers, millimeter waves and direct sequence spread spectrum (DSSS) at radio frequencies.

Astronomy. Laser telemetry from space.

PubMed

Bland-Hawthorn, Joss; Harwit, Alex; Harwit, Martin

2002-07-26

Space missions currently on the drawing boards are expected to gather data at rates exceeding the transmission capabilities of today's telemetry systems by many orders of magnitude. Even on current missions, onboard data compression techniques are being implemented to compensate for lack of transmission speed. But while data compression can minimize the loss of data, it is no substitute for transmitting all of the data through a faster communications link. The transmission problem will soon reach crisis proportions and will affect astronomical, Earth resources, geophysical, meteorological, planetary and other space science missions. To overcome this communications bottleneck, the authors advocate the implementation of telemetry systems based on near-infrared laser transmission techniques. The fiber-optics communications industry has developed most of the basic components required for signal transmission in this wavelength band, which should make such a system affordable on scales relevant to the cost of anticipated space science missions.

Interplanetary and interstellar optical communication between intelligent beings: a historical approach

NASA Astrophysics Data System (ADS)

Lemarchand, Guillermo A.

1996-06-01

A review of the different proposals made to establish contact with hypothetical planetary neighbors is done. For almost 100 years (approximately 1822-1921) the dominant paradigm for signaling extraterrestrial beings, were based in the exchange of light beam signals. After the success of wireless transatlantic communications and the discovery of radio signals from the cosmos, the main scientific proposals to contact extraterrestrials were based on radio signals. Nevertheless, the development of lasers and other nonlinear optical devices, led into a new set of proposals to use them for interplanetary and interstellar communication means. A review of these proposals and the detection of extraterrestrial technological activities in the optical domain is made. A summary of the requirements needed to explore the astrophysics of shortest timescales is described, in order to develop the nano and sub-nanosecond detectors that could be used to detect interstellar pulsed laser signals.

Statistical simulation of information transfer through non-line-of-sight atmospheric optical communication channels

NASA Astrophysics Data System (ADS)

Tarasenkov, M. V.; Belov, V. V.; Poznakharev, E. S.

2017-11-01

Impulse response of non-line-of-sight atmospheric communication channels at wavelengths of 0.3, 0.5, and 0.9 μm are compared for the case in which the optical axes of the receiver and laser radiation lie in the plane perpendicular to the Earth's surface. The most efficient communication channel depending on the base distance is determined. For a wavelength of 0.5 μm and a concrete variant of the transceiving part of the communication system, the limiting communication range and the limiting repetition frequency of pulses that can be transmitted through the communication channel are estimated.

Monolithic narrow-linewidth InGaAsP semiconductor laser for coherent optical communications

NASA Technical Reports Server (NTRS)

Palfrey, S. L.; Enstrom, R. E.; Longeway, P. A.

1989-01-01

A design for a monolithic narrow-linewidth InGaAsP diode laser has been developed using a multiple-quantum-well (MQW) extended-passive-cavity distributed-Bragg-reflector (DBR) laser design. Theoretical results indicate that this structure has the potential for a linewidth of 100 kHz or less. To realize this device, a number of the fabrication techniques required to integrate low-loss passive waveguides with active regions have been developed using a DBR laser structure. In addition, the MOCVD growth of InGaAs MQW laser structures has been developed, and threshold current densities as low as 1.6 kA/sq cm have been obtained from broad-stripe InGaAs/InGaAsP separate-confinement-heterostructure MQW lasers.

Purified frequency modulation of a quantum cascade laser with an all-optical approach.

PubMed

Peng, Chen; Zhou, Haijun; Zhu, Liguo; Chen, Tao; Liu, Qiao; Wang, Detian; Li, Jiang; Peng, Qixian; Chen, Gang; Li, Zeren

2017-11-01

Purified frequency modulation (FM) is demonstrated in a standard middle-infrared quantum cascade laser by illuminating its front facet with two near-infrared (NIR) lasers. A 2 mW laser at 1550 nm is utilized to modulate the amplitude and frequency of a quantum cascade laser, and the associated amplitude modulation (AM) is suppressed by a 1.85 mW laser at 850 nm. Due to the hot carrier effect and the increment of electron temperature, the AM has been decreased. In addition, the free carrier concentration increases in the active region due to the two NIR illuminations, which enhance the FM. Purified FM is beneficial in improving the signal fidelity for free-space optical communication and high-speed FM spectroscopy.

All solid-state high power visible laser

NASA Technical Reports Server (NTRS)

Grossman, William M.

1993-01-01

The overall objective of this Phase 2 effort was to develop and deliver to NASA a high repetition rate laser-diode-pumped solid-state pulsed laser system with output in the green portion of the spectrum. The laser is for use in data communications, and high efficiency, short pulses, and low timing jitter are important features. A short-pulse 1 micron laser oscillator, a new multi-pass amplifier to boost the infrared power, and a frequency doubler to take the amplified infrared pulsed laser light into the green. This produced 1.5 W of light in the visible at a pulse repetition rate of 20 kHz in the laboratory. The pulses have a full-width at half maximum of near 1 ns. The results of this program are being commercialized.

Image Processing In Laser-Beam-Steering Subsystem

NASA Technical Reports Server (NTRS)

Lesh, James R.; Ansari, Homayoon; Chen, Chien-Chung; Russell, Donald W.

1996-01-01

Conceptual design of image-processing circuitry developed for proposed tracking apparatus described in "Beam-Steering Subsystem For Laser Communication" (NPO-19069). In proposed system, desired frame rate achieved by "windowed" readout scheme in which only pixels containing and surrounding two spots read out and others skipped without being read. Image data processed rapidly and efficiently to achieve high frequency response.

Why Aren’t Lightsabers Real Yet? Get the Lowdown from a Laser Physicist

ScienceCinema

Hunsberger, Maren; Liao, Zhi

2018-06-22

The release of "Star Wars: The Force Awakens" begs the obvious question: Why aren't lightsabers real yet? LLNL science communicator Maren Hunsberger gets the lowdown from laser physicist Zhi Liao in this first installment of "Inside the Lab," a new YouTube series exploring crazy-cool science questions.

Experimental verification of arm-locking for LISA using electronic phase delay [rapid communication

NASA Astrophysics Data System (ADS)

Thorpe, J. I.; Mueller, G.

2005-07-01

We present results of an electronic model of arm-locking, a proposed technique for reducing the laser phase noise in the laser interferometer space antenna (LISA). The model is based on a delay of 500 ms, achieved using the electronic phase delay (EPD) method. The observed behavior is consistent with predictions.

Laser Light Fiber Communication,

DTIC Science & Technology

1980-10-14

001 068 C)LASER FIGT3IBER OMNICATION BICICJ-,HuanN/CAnIOu Country off origin: China Translated by: :F3 -8D01SCITRAN A~s---qnrt / Requester: FTD/TQTA...TXS ’ -’- Approved ffor public release; distribution DTIC T:’’w fBy _ Conty f riin. Codes Trans ated by: CITRA Accssio THIS TRANSLATION IS A REI

Optical communications and a comparison of optical technologies for a high data rate return link from Mars

NASA Technical Reports Server (NTRS)

Spence, Rodney L.

1993-01-01

The important principles of direct- and heterodyne-detection optical free-space communications are reviewed. Signal-to-noise-ratio (SNR) and bit-error-rate (BER) expressions are derived for both the direct-detection and heterodyne-detection optical receivers. For the heterodyne system, performance degradation resulting from received-signal and local oscillator-beam misalignment and laser phase noise is analyzed. Determination of interfering background power from local and extended background sources is discussed. The BER performance of direct- and heterodyne-detection optical links in the presence of Rayleigh-distributed random pointing and tracking errors is described. Finally, several optical systems employing Nd:YAG, GaAs, and CO2 laser sources are evaluated and compared to assess their feasibility in providing high-data-rate (10- to 1000-Mbps) Mars-to-Earth communications. It is shown that the root mean square (rms) pointing and tracking accuracy is a critical factor in defining the system transmitting laser-power requirements and telescope size and that, for a given rms error, there is an optimum telescope aperture size that minimizes the required power. The results of the analysis conducted indicate that, barring the achievement of extremely small rms pointing and tracking errors (less than 0.2 microrad), the two most promising types of optical systems are those that use an Nd:YAG laser (lambda = 1.064 microns) and high-order pulse position modulator (PPM) and direct detection, and those that use a CO2 laser (lambda = 10.6 microns) and phase shifting keying homodyne modulation and coherent detection. For example, for a PPM order of M = 64 and an rms pointing accuracy of 0.4 microrad, an Nd:YAG system can be used to implement a 100-Mbps Mars link with a 40-cm transmitting telescope, a 20-W laser, and a 10-m receiving photon bucket. Under the same conditions, a CO2 system would require 3-m transmitting and receiving telescopes and a 32-W laser to implement such a link. Other types of optical systems, such as a semiconductor laser systems, are impractical in the presence of large rms pointing errors because of the high power requirements of the 100-Mbps Mars link, even when optimal-size telescopes are used.

Conceptual Design of the Adaptive Optics System for the Laser Communication Relay Demonstration Ground Station at Table Mountain

NASA Technical Reports Server (NTRS)

Roberts, Lewis C., Jr.; Page, Norman A.; Burruss, Rick S.; Truong, Tuan N.; Dew, Sharon; Troy, Mitchell

2013-01-01

The Laser Communication Relay Demonstration will feature a geostationary satellite communicating via optical links to multiple ground stations. The first ground station (GS-1) is the 1m OCTL telescope at Table Mountain in California. The optical link will utilize pulse position modulation (PPM) and differential phase shift keying (DPSK) protocols. The DPSK link necessitates that adaptive optics (AO) be used to relay the incoming beam into the single mode fiber that is the input of the modem. The GS-1 AO system will have two MEMS Deformable mirrors to achieve the needed actuator density and stroke limit. The AO system will sense the aberrations with a Shack-Hartmann wavefront sensor using the light from the communication link's 1.55 microns laser to close the loop. The system will operate day and night. The system's software will be based on heritage software from the Palm 3000 AO system, reducing risk and cost. The AO system is being designed to work at r(sub 0) greater than 3.3 cm (measured at 500 nm and zenith) and at elevations greater than 20deg above the horizon. In our worst case operating conditions we expect to achieve Strehl ratios of over 70% (at 1.55 microns), which should couple 57% of the light into the single mode DPSK fiber. This paper describes the conceptual design of the AO system, predicted performance and discusses some of the trades that were conducted during the design process.

Experimental demonstration of OFDM/OQAM transmission with DFT-based channel estimation for visible laser light communications

NASA Astrophysics Data System (ADS)

He, Jing; Shi, Jin; Deng, Rui; Chen, Lin

2017-08-01

Recently, visible light communication (VLC) based on light-emitting diodes (LEDs) is considered as a candidate technology for fifth-generation (5G) communications, VLC is free of electromagnetic interference and it can simplify the integration of VLC into heterogeneous wireless networks. Due to the data rates of VLC system limited by the low pumping efficiency, small output power and narrow modulation bandwidth, visible laser light communication (VLLC) system with laser diode (LD) has paid more attention. In addition, orthogonal frequency division multiplexing/offset quadrature amplitude modulation (OFDM/OQAM) is currently attracting attention in optical communications. Due to the non-requirement of cyclic prefix (CP) and time-frequency domain well-localized pulse shapes, it can achieve high spectral efficiency. Moreover, OFDM/OQAM has lower out-of-band power leakage so that it increases the system robustness against inter-carrier interference (ICI) and frequency offset. In this paper, a Discrete Fourier Transform (DFT)-based channel estimation scheme combined with the interference approximation method (IAM) is proposed and experimentally demonstrated for VLLC OFDM/OQAM system. The performance of VLLC OFDM/OQAM system with and without DFT-based channel estimation is investigated. Moreover, the proposed DFT-based channel estimation scheme and the intra-symbol frequency-domain averaging (ISFA)-based method are also compared for the VLLC OFDM/OQAM system. The experimental results show that, the performance of EVM using the DFT-based channel estimation scheme is improved about 3dB compared with the conventional IAM method. In addition, the DFT-based channel estimation scheme can resist the channel noise effectively than that of the ISFA-based method.

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.

20-Gbps optical LiFi transport system.

PubMed

Ying, Cheng-Ling; Lu, Hai-Han; Li, Chung-Yi; Cheng, Chun-Jen; Peng, Peng-Chun; Ho, Wen-Jeng

2015-07-15

A 20-Gbps optical light-based WiFi (LiFi) transport system employing vertical-cavity surface-emitting laser (VCSEL) and external light injection technique with 16-quadrature amplitude modulation (QAM)-orthogonal frequency-division multiplexing (OFDM) modulating signal is proposed. Good bit error rate (BER) performance and clear constellation map are achieved in our proposed optical LiFi transport systems. An optical LiFi transport system, delivering 16-QAM-OFDM signal over a 6-m free-space link, with a data rate of 20 Gbps, is successfully demonstrated. Such a 20-Gbps optical LiFi transport system provides the advantage of a free-space communication link for high data rates, which can accelerate the visible laser light communication (VLLC) deployment.

Fraunhofer filters to reduce solar background for optical communications

NASA Technical Reports Server (NTRS)

Kerr, E. L.

1986-01-01

A wavelength that lies within a spectral interval of reduced solar emission (a Fraunhofer line) can carry optical communications with reduced interference from direct or reflected background sunlight. Suitable Fraunhofer lines are located within the tuning range of good candidate lasers. The laser should be tunable dynamically to track Doppler shifts in the sunlight incident on any solar system body that may appear in the background as viewed by the receiver. A Fraunhofer filter used with a direct-detection receiver should be tuned to match the Doppler shifts of the source and background. The required tuning calculated here for various situations is also required if, instead, one uses a heterodyne receiver with limited post-detection bandwidth.

Thermal effects of optical antenna under the irradiation of laser

NASA Astrophysics Data System (ADS)

Sun, Yi; Li, Fu; Yang, Wenqiang; Yang, Jianfeng

2017-10-01

The laser communication terminal is a precision optical, mechanical, electrical integration device which operations extremely high accuracy. It is hard to improve the space environment adaptability in the hash vibration, thermal cycling, high vacuum and radiation conditions space environment. Accordingly, the optical antenna will be influenced by space thermal environment. Laser energy will be absorbed when optical antenna under the irradiation of laser. It can contribute to thermal distortion and make the beam quality degradation which affects the performance of laser communications links. This influence will aggravate when the laser power rising.Wavefront aberration is the distance between the ideal reference sphere and the actual distorted wavefront. The smaller the wavefront aberration, the better the optical performance of the optical antenna. On the contrary, the greater the wavefront aberration, the worse the performance of the optical antenna or even affect the normal operation of the optical antenna. The performance index of the optical antenna generally requires the wavefront aberration to be better than λ/20. Due to the different thermal and thermal expansion coefficients of the material, the effect of thermal deformation on the optical antenna can be reduced by matching the appropriate material. While the appropriate support structure and proper heat dissipation design can also reduce the impact. In this paper, the wavefront aberration of the optical antenna is better than λ/50 by the material matching and the appropriate support structure and the secondary design of the diameter of 5mm hole thermal design.

Temperature dependence of spectral linewidth of InAs/InP quantum dot distributed feedback lasers

NASA Astrophysics Data System (ADS)

Duan, J.; Huang, H.; Schires, K.; Poole, P. J.; Wang, C.; Grillot, F.

2018-02-01

In this paper, we investigate the temperature dependence of spectral linewidth of InAs/InP quantum dot distributed feedback lasers. In comparison with their quantum well counterparts, results show that quantum dot lasers have spectral linewidths rather insensitive to the temperature with minimum values below 200 kHz in the range of 283K to 303K. The experimental results are also well confirmed by numerical simulations. Overall, this work shows that quantum dot lasers are excellent candidates for various applications such as coherent communication systems, high-resolution spectroscopy, high purity photonic microwave generation and on-chip atomic clocks.

Research on atmospheric transmission distortion of Gauss laser using multiple phase screen method

NASA Astrophysics Data System (ADS)

Zhang, Yizhuo; Wang, Qiushi; Gu, Haidong

2018-02-01

The laser beam is attenuated, broadened, defocused and may even be deflected from its initial propagation direction as it propagates through the atmosphere. It leads to the decrease of the laser intensity of the receiving surface. Gauss beam is the fundamental components of all possible laser waveforms. Therefore, research on the transmission of the Gauss laser has far-reaching consequences in optical communication, weaponry, target designation, ranging, remote sensing and other applications that require transmission of laser beams through the atmosphere. In this paper, we propose a laboratory simulation method using multi-phase screen to calculate the effects of atmospheric turbulence. Theoretical analysis of Gauss laser transmission in the atmosphere is given. By calculating the propagation of the Gauss beam TEM00, the far field intensity and phase distribution is shown. By the given method, the optical setup is presented and used for optimizing the adaptive optics algorithm.

Theory and simulent design of a type of auto-self-protecting optical switches

NASA Astrophysics Data System (ADS)

Li, Binhong; Peng, Songcun

1990-06-01

As the use of lasers in the military and in the civilian economy increases with each passing day, it is often necessary for the human eye or sensitive instruments to observe weak lasers, such as the return waves of laser radar and laser communications signals; but it is also necessary to provide protection against damage to the eye from the strong lasers of enemy laser weapons. For this reason, it is necessary to have a kind of automatic optical self-protecting switch. Based upon a study of the transmitting and scattering characteristics of multilayer dielectric optical waveguides, a practical computer program is set up for designing a type of auto-self-protecting optical switch with a computer model by using the nonlinear property of dielectric layers and the plasma behavior of metal substrates. This technique can be used to protect the human eye and sensitive detectors from damage caused by strong laser beams.

A cascaded silicon Raman laser

NASA Astrophysics Data System (ADS)

Rong, Haisheng; Xu, Shengbo; Cohen, Oded; Raday, Omri; Lee, Mindy; Sih, Vanessa; Paniccia, Mario

2008-03-01

One of the major advantages of Raman lasers is their ability to generate coherent light in wavelength regions that are not easily accessible with other conventional types of lasers. Recently, efficient Raman lasing in silicon in the near-infrared region has been demonstrated, showing great potential for realizing low-cost, compact, room-temperature lasers in the mid-infrared region. Such lasers are highly desirable for many applications, ranging from trace-gas sensing, environmental monitoring and biomedical analysis, to industrial process control, and free-space communications. Here we report the first experimental demonstration of cascaded Raman lasing in silicon, opening the path to extending the lasing wavelength from the near- to mid-infrared region. Using a 1,550-nm pump source, we achieve stable, continuous-wave, second-order cascaded lasing at 1,848 nm with an output power exceeding 5 mW. The laser operates in single mode, and the laser linewidth is measured to be <2.5 MHz.

Bandgap engineering of InGaAsP/InP laser structure by photo-absorption-induced point defects

NASA Astrophysics Data System (ADS)

Kaleem, Mohammad; Nazir, Sajid; Saqib, Nazar Abbas

2016-03-01

Integration of photonic components on the same photonic wafer permits future optical communication systems to be dense and advanced performance. This enables very fast information handling between photonic active components interconnected through passive optical low loss channels. We demonstrate the UV-Laser based Quantum Well Intermixing (QWI) procedure to engineer the band-gap of compressively strained InGaAsP/InP Quantum Well (QW) laser material. We achieved around 135nm of blue-shift by simply applying excimer laser (λ= 248nm). The under observation laser processed material also exhibits higher photoluminescence (PL) intensity. Encouraging experimental results indicate that this simple technique has the potential to produce photonic integrated devices and circuits.

Spontaneous generation of frequency combs in QD lasers

NASA Astrophysics Data System (ADS)

Columbo, Lorenzo Luigi; Bardella, Paolo; Gioannini, Mariangela

2018-02-01

We report a systematic analysis of the phenomenon of self-generation of optical frequency combs in single section Fabry-Perot Quantum Dot lasers using a Time Domain Travelling Wave model. We show that the carriers grating due to the standing wave pattern (spatial hole burning) peculiar of Quantum Dots laser and the Four Wave Mixing are the key ingredients to explain spontaneous Optical Frequency Combs in these devices. Our results well agree with recent experimental evidences reported in semiconductor lasers based on Quantum Dots and Quantum Dashes active material and pave the way to the development of a simulation tool for the design of these comb laser sources for innovative applications in the field of high-data rate optical communications.

A solar simulator-pumped gas laser for the direct conversion of solar energy

NASA Technical Reports Server (NTRS)

Weaver, W. R.; Lee, J. H.

1981-01-01

Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

Feasibility assessment of optical technologies for reliable high capacity feeder links

NASA Astrophysics Data System (ADS)

Witternigg, Norbert; Schönhuber, Michael; Leitgeb, Erich; Plank, Thomas

2013-08-01

Space telecom scenarios like data relay satellite and broadband/broadcast service providers require reliable feeder links with high bandwidth/data rate for the communication between ground station and satellite. Free space optical communication (FSOC) is an attractive alternative to microwave links, improving performance by offering abundant bandwidth at small apertures of the optical terminals. At the same time Near-Earth communication by FSOC avoids interference with other services and is free of regulatory issues. The drawback however is the impairment by the laser propagation through the atmosphere at optical wavelengths. Also to be considered are questions of eye safety for ground personnel and aviation. In this paper we assess the user requirements for typical space telecom scenarios and compare these requirements with solutions using optical data links through the atmosphere. We suggest a site diversity scheme with a number of ground stations and a switching scheme using two optical terminals on-board the satellite. Considering the technology trade-offs between four different optical wavelengths we recommend the future use of 1.5 μm laser technology and calculate a link budget for an atmospheric condition of light haze on the optical path. By comparing link budgets we show an outlook to the future potential use of 10 μm laser technology.

An Overview of Communications Technology and Development Efforts for 2015 SBIR Phase I

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Steele, Gynelle C.

2017-01-01

This report highlights innovative SBIR 2015 Phase I projects specifically addressing areas in Communications Technology and Development which is one of six core competencies at NASA Glenn Research Center. There are fifteen technologies featured with emphasis on a wide spectrum of applications such as novel solid state lasers for space-based water vapor dial; wide temperature, high voltage and energy density capacitors for aerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser for methane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites; a SIC-based microcontroller for high-temperature in-situ instruments and systems; improved yield, performance and reliability of high-actuator-count deformable mirrors; embedded multifunctional optical sensor system; switching electronics for space-based telescopes with advanced AO systems; integrated miniature DBR laser module for Lidar instruments; and much more. Each article in this booklet describes an innovation, technical objective, and highlights NASA commercial and industrial applications. space-based water vapor dial; wide temperature, high voltage and energy density capacitors foraerospace exploration; instrument for airborne measurement of carbonyl sulfide; high-power tunable seed laser formethane Lidar transmitter; ROC-rib deployable ka-band antenna for nanosatellites.

Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

PubMed Central

Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

2017-01-01

We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ∼3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers. PMID:28322327

Theoretical analyses of an injection-locked diode-pumped rubidium vapor laser.

PubMed

Cai, He; Gao, Chunqing; Liu, Xiaoxu; Wang, Shunyan; Yu, Hang; Rong, Kepeng; An, Guofei; Han, Juhong; Zhang, Wei; Wang, Hongyuan; Wang, You

2018-04-02

Diode-pumped alkali lasers (DPALs) have drawn much attention since they were proposed in 2001. The narrow-linewidth DPAL can be potentially applied in the fields of coherent communication, laser radar, and atomic spectroscopy. In this study, we propose a novel protocol to narrow the width of one kind of DPAL, diode-pumped rubidium vapor laser (DPRVL), by use of an injection locking technique. A kinetic model is first set up for an injection-locked DPRVL with the end-pumped configuration. The laser tunable duration is also analyzed for a continuous wave (CW) injection-locked DPRVL system. Then, the influences of the pump power, power of a master laser, and reflectance of an output coupler on the output performance are theoretically analyzed. The study should be useful for design of a narrow-linewidth DPAL with the relatively high output.

Carbon Nanotube Mode-Locked Thulium Fiber Laser With 200 nm Tuning Range

NASA Astrophysics Data System (ADS)

Meng, Yafei; Li, Yao; Xu, Yongbing; Wang, Fengqiu

2017-03-01

We demonstrated a mode-locked thulium/holmium (Tm/Ho) fiber laser continuously tunable across 200 nm (from 1860 nm to 2060 nm), which to the best of our knowledge represents the widest tuning range ever achieved for a passively mode-locked fiber laser oscillator. The combined use of a broadband carbon nanotube (CNT) saturable absorber and a diffraction grating mirror ensures ultra-broad tuning range, superb stability and repeatability, and makes the demonstrated laser a highly practical source for spectroscopy, imaging and optical communications. The laser emits <5 ps pulses with an optical spectral bandwidth of ˜3 nm across the full tuning range. Our results indicate that carbon nanotubes can be an excellent saturable absorber for achieving gain-bandwidth-limited tunable operation for 2 μm thulium fiber lasers.

Ionization processes in combined high-voltage nanosecond - laser discharges in inert gas

NASA Astrophysics Data System (ADS)

Starikovskiy, Andrey; Shneider, Mikhail; PU Team

2016-09-01

Remote control of plasmas induced by laser radiation in the atmosphere is one of the challenging issues of free space communication, long-distance energy transmission, remote sensing of the atmosphere, and standoff detection of trace gases and bio-threat species. Sequences of laser pulses, as demonstrated by an extensive earlier work, offer an advantageous tool providing access to the control of air-plasma dynamics and optical interactions. The avalanche ionization induced in a pre-ionized region by infrared laser pulses where investigated. Pre-ionization was created by an ionization wave, initiated by high-voltage nanosecond pulse. Then, behind the front of ionization wave extra avalanche ionization was initiated by the focused infrared laser pulse. The experiment was carried out in argon. It is shown that the gas pre-ionization inhibits the laser spark generation under low pressure conditions.

Long-distance quantum communication with atomic ensembles and linear optics.

PubMed

Duan, L M; Lukin, M D; Cirac, J I; Zoller, P

2001-11-22

Quantum communication holds promise for absolutely secure transmission of secret messages and the faithful transfer of unknown quantum states. Photonic channels appear to be very attractive for the physical implementation of quantum communication. However, owing to losses and decoherence in the channel, the communication fidelity decreases exponentially with the channel length. Here we describe a scheme that allows the implementation of robust quantum communication over long lossy channels. The scheme involves laser manipulation of atomic ensembles, beam splitters, and single-photon detectors with moderate efficiencies, and is therefore compatible with current experimental technology. We show that the communication efficiency scales polynomially with the channel length, and hence the scheme should be operable over very long distances.

Vertical electro-absorption modulator design and its integration in a VCSEL

NASA Astrophysics Data System (ADS)

Marigo-Lombart, L.; Calvez, S.; Arnoult, A.; Thienpont, H.; Almuneau, G.; Panajotov, K.

2018-04-01

Electro-absorption modulators, either embedded in CMOS technology or integrated with a semiconductor laser, are of high interest for many applications such as optical communications, signal processing and 3D imaging. Recently, the integration of a surface-normal electro-absorption modulator into a vertical-cavity surface-emitting laser has been considered. In this paper we implement a simple quantum well electro-absorption model and design and optimize an asymmetric Fabry-Pérot semiconductor modulator while considering all physical properties within figures of merit. We also extend this model to account for the impact of temperature on the different parameters involved in the calculation of the absorption, such as refractive indices and exciton transition broadening. Two types of vertical modulator structures have been fabricated and experimentally characterized by reflectivity and photocurrent measurements demonstrating a very good agreement with our model. Finally, preliminary results of an electro-absorption modulator vertically integrated with a vertical-cavity surface-emitting laser device are presented, showing good modulation performances required for high speed communications.

Architectural design of a ground-based deep-space optical reception antenna

NASA Technical Reports Server (NTRS)

Kerr, E. L.

1989-01-01

An architectural design of a ground-based antenna (telescope) for receiving optical communications from deep space is presented. Physical and optical parameters, and their effect on the performance and cost considerations, are described. The channel capacity of the antenna is 100 kbits/s from Saturn and 5 Mbits/s from Mars. A novel sunshade is designed to permit optical communication even when the deep-space laser source is as close to the sun as 12 deg. Inserts in the tubes of the sunshade permit operations at solar elongations as small as 6 or 3 deg. The Nd:YAG source laser and the Fraunhofer filter (a narrow-band predetection optical filter) are tuned to match the Doppler shifts of the source and background. A typical Saturn-to-earth data link can reduce its source power requirement from 8.2 W to 2 W of laser output by employing a Fraunhofer filter instead of a conventional multilayer dielectric filter.

Experimental validation of phase-only pre-compensation over 494  m free-space propagation.

PubMed

Brady, Aoife; Berlich, René; Leonhard, Nina; Kopf, Teresa; Böttner, Paul; Eberhardt, Ramona; Reinlein, Claudia

2017-07-15

It is anticipated that ground-to-geostationary orbit (GEO) laser communication will benefit from pre-compensation of atmospheric turbulence for laser beam propagation through the atmosphere. Theoretical simulations and laboratory experiments have determined its feasibility; extensive free-space experimental validation has, however, yet to be fulfilled. Therefore, we designed and implemented an adaptive optical (AO)-box which pre-compensates an outgoing laser beam (uplink) using the measurements of an incoming beam (downlink). The setup was designed to approximate the baseline scenario over a horizontal test range of 0.5 km and consisted of a ground terminal with the AO-box and a simplified approximation of a satellite terminal. Our results confirmed that we could focus the uplink beam on the satellite terminal using AO under a point-ahead angle of 28 μrad. Furthermore, we demonstrated a considerable increase in the intensity received at the satellite. These results are further testimony to AO pre-compensation being a viable technique to enhance Earth-to-GEO optical communication.

High-speed pulse-shape generator, pulse multiplexer

DOEpatents

Burkhart, Scott C.

2002-01-01

The invention combines arbitrary amplitude high-speed pulses for precision pulse shaping for the National Ignition Facility (NIF). The circuitry combines arbitrary height pulses which are generated by replicating scaled versions of a trigger pulse and summing them delayed in time on a pulse line. The combined electrical pulses are connected to an electro-optic modulator which modulates a laser beam. The circuit can also be adapted to combine multiple channels of high speed data into a single train of electrical pulses which generates the optical pulses for very high speed optical communication. The invention has application in laser pulse shaping for inertial confinement fusion, in optical data links for computers, telecommunications, and in laser pulse shaping for atomic excitation studies. The invention can be used to effect at least a 10.times. increase in all fiber communication lines. It allows a greatly increased data transfer rate between high-performance computers. The invention is inexpensive enough to bring high-speed video and data services to homes through a super modem.

Effect of non-Kolmogorov turbulence on BER performance in uplink ground-to-satellite laser communication

NASA Astrophysics Data System (ADS)

Wang, Yi; Zhang, Ao; Ma, Jing; Guo, Qiang

2016-12-01

Based on the non-Kolmogorov turbulence model of the stratosphere, a theoretical model for the influence of the angle of arrival (AOA) fluctuations on the performance of the bit error rate (BER) is established. A closed form expression of BER is then derived based on this model. Then, considering the combined effect of scintillation, beam wander and AOA fluctuations, the probability density function of the received intensity and the closed form expressions of BER for uplink are derived. Coherent detection of Circle Polarization Shift Keying modulation which is suitable for ground-to-satellite laser communication is employed. For an uplink, the BER performance is emulation analyzed and compared to the condition without taking AOA fluctuations into account. And the variation of BER as a function of AOA fluctuations has also been researched. The influence of intensity scintillation, beam wander and AOA fluctuations on BER has been analyzed based on laser transmit power restrictions.

Chaos synchronization communication using extremely unsymmetrical bidirectional injections.

PubMed

Zhang, Wei Li; Pan, Wei; Luo, Bin; Zou, Xi Hua; Wang, Meng Yao; Zhou, Zhi

2008-02-01

Chaos synchronization and message transmission between two semiconductor lasers with extremely unsymmetrical bidirectional injections (EUBIs) are discussed. By using EUBIs, synchronization is realized through injection locking. Numerical results show that if the laser subjected to strong injection serves as the receiver, chaos pass filtering (CPF) of the system is similar to that of unidirectional coupled systems. Moreover, if the other laser serves as the receiver, a stronger CPF can be obtained. Finally, we demonstrate that messages can be extracted successfully from either of the two transmission directions of the system.

An evaluation of SAO sites for laser operations

NASA Technical Reports Server (NTRS)

Thorp, J. M.; Bush, M. A.; Pearlman, M. R.

1974-01-01

Operational criteria are provided for the selection of laser tracking sites for the Earth and Ocean Physics Applications Program. A compilation of data is given concerning the effect of weather conditions on laser and Baker-Nunn camera operations. These data have been gathered from the Smithsonian astrophysical observing station sites occupied since the inception of the satellite tracking program. Also given is a brief description of each site, including its characteristic weather conditions, comments on communications and logistics, and a summary of the terms of agreement under which the station is or was operated.

Demonstration of a low bandwidth 1.06-micron optical phase-locked loop for coherent homodyne communication

NASA Technical Reports Server (NTRS)

Day, T.; Farinas, A. D.; Byer, R. L.

1990-01-01

A type II 1.06-micron optical phase-locked loop (OPLL) for use in a coherent homodyne receiver is discussed. Diode-laser-pumped solid-state lasers are used for both the local oscillator and transmitter, because their phase noise is significantly lower than that of diode lasers. Closed-loop RMS phase noise of less than 12 mrad (0.69 deg) is achieved, and modulation-demodulation in bulk modulators at rates from 20 kHz to 20 MHz with less than 19 deg of modulation depth is demonstrated.

Generation of dark solitons in erbium-doped fiber lasers based Sb(2)Te(3) saturable absorbers.

PubMed

Liu, Wenjun; Pang, Lihui; Han, Hainian; Tian, Wenlong; Chen, Hao; Lei, Ming; Yan, Peiguang; Wei, Zhiyi

2015-10-05

Dark solitons, which have better stability in the presence of noise, have potential applications in optical communication and ultrafast optics. In this paper, the dark soliton formation in erbium-doped fiber lasers based Sb(2)Te(3) saturable absorber (SA) is first experimentally demonstrated. The Sb(2)Te(3) SA is fabricated by using the pulsed laser deposition method. The generated dark solitons are centered at the wavelength of 1530 nm and repetition rate of 94 MHz. Analytic solutions for dark solitons are also obtained theoretically.

FAST TRACK COMMUNICATION: Inhomogeneous charge redistribution in Xe clusters exposed to an intense extreme ultraviolet free electron laser

NASA Astrophysics Data System (ADS)

Iwayama, H.; Sugishima, A.; Nagaya, K.; Yao, M.; Fukuzawa, H.; Motomura, K.; Liu, X.-J.; Yamada, A.; Wang, C.; Ueda, K.; Saito, N.; Nagasono, M.; Tono, K.; Yabashi, M.; Ishikawa, T.; Ohashi, H.; Kimura, H.; Togashi, T.

2010-08-01

The emission of highly charged ions from Xe clusters exposed to intense extreme ultraviolet laser pulses (λ ~ 52 nm) from the free electron laser in Japan was investigated using ion momentum spectroscopy. With increasing average cluster size, we observed multiply charged ions Xez + up to z = 3. From kinetic energy distributions, we found that multiply charged ions were generated near the cluster surface. Our results suggest that charges are inhomogeneously redistributed in the cluster to lower the total energy stored in the clusters.

Ultrafast Optics: Vector Cavity Fiber Lasers - Physics and Technology

DTIC Science & Technology

2016-06-14

with a quasi- vector cavity both numerically and experimentally. It is expected that through the study a deep and comprehensive understanding on the...799-801, Jun. 1997. 31. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like pulse in a gain-guided soliton fiber laser," Opt...solitons in a ring fiber laser," Optics Communications 281 (22), 5614 (2008). 110. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like

Ultrafast Optics: Vector Cavity Laser - Physics and Technology

DTIC Science & Technology

2016-06-14

with a quasi- vector cavity both numerically and experimentally. It is expected that through the study a deep and comprehensive understanding on the...799-801, Jun. 1997. 31. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like pulse in a gain-guided soliton fiber laser," Opt...solitons in a ring fiber laser," Optics Communications 281 (22), 5614 (2008). 110. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like

Ultrafast Optics - Vector Cavity Lasers: Physics and Technology

DTIC Science & Technology

2016-06-14

with a quasi- vector cavity both numerically and experimentally. It is expected that through the study a deep and comprehensive understanding on the...799-801, Jun. 1997. 31. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like pulse in a gain-guided soliton fiber laser," Opt...solitons in a ring fiber laser," Optics Communications 281 (22), 5614 (2008). 110. L. M. Zhao, D. Y. Tang, J. Wu, X. Q. Fu, and S. C. Wen , "Noise-like

Design of smart composite platforms for adaptive trust vector control and adaptive laser telescope for satellite applications

NASA Astrophysics Data System (ADS)

Ghasemi-Nejhad, Mehrdad N.

2013-04-01

This paper presents design of smart composite platforms for adaptive trust vector control (TVC) and adaptive laser telescope for satellite applications. To eliminate disturbances, the proposed adaptive TVC and telescope systems will be mounted on two analogous smart composite platform with simultaneous precision positioning (pointing) and vibration suppression (stabilizing), SPPVS, with micro-radian pointing resolution, and then mounted on a satellite in two different locations. The adaptive TVC system provides SPPVS with large tip-tilt to potentially eliminate the gimbals systems. The smart composite telescope will be mounted on a smart composite platform with SPPVS and then mounted on a satellite. The laser communication is intended for the Geosynchronous orbit. The high degree of directionality increases the security of the laser communication signal (as opposed to a diffused RF signal), but also requires sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum increases the data transmission rates, but laser systems require large amounts of power, which increases the mass and complexity of the supporting systems. In addition, the laser communication on the Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also addresses the design of an active composite platform to be used to simultaneously point and stabilize an intersatellite laser communication telescope with micro-radian pointing resolution. The telescope is a Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary). The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or else the optical properties of the system will be severely degraded. The alignment will also have to be maintained during thruster firings, which will require vibration suppression capabilities of the system as well. The innovative platform has been designed to have tip-tilt pointing and simultaneous multi-degree-of-freedom vibration isolation capability for pointing stabilization. Analytical approaches have been employed for determining the loads in the components as well as optimizing the design of the system. The different critical components such as telescope tube struts, flexure joints, and the secondary mirror mount have been designed and analyzed using finite element technique. The Simultaneous Precision Positioning and Vibration Suppression (SPPVS) smart composites platforms for the adaptive TVC and adaptive composite telescope are analogous (e.g., see work by Ghasemi-Nejhad and co-workers [1, 2]), where innovative concepts and control strategies are introduced, and experimental verifications of simultaneous thrust vector control and vibration isolation of satellites were performed. The smart composite platforms function as an active structural interface between the main thruster of a satellite and the satellite structure for the adaptive TVC application and as an active structural interface between the main smart composite telescope and the satellite structure for the adaptive laser communication application. The cascaded multiple feedback loops compensate the hysteresis (for piezoelectric stacks inside the three linear actuators that individually have simultaneous precision positioning and vibration suppression), dead-zone, back-lash, and friction nonlinearities very well, and provide precision and quick smart platform control and satisfactory thrust vector control capability. In addition, for example for the adaptive TVC, the experimental results show that the smart composite platform satisfactorily provided precision and fast smart platform control as well as the satisfactory thrust vector control capability. The vibration controller isolated 97% of the vibration energy due to the thruster firing.

Contamination and Radiation Effects on Nonlinear Crystals for Space Laser Systems

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossain A.; Dowdye, Edward; Jamison, Tracee; Canham, John; Jaeger, Todd

2005-01-01

Space Lasers are vital tools for NASA s space missions and military applications. Although, lasers are highly reliable on the ground, several past space laser missions proved to be short-lived and unreliable. In this communication, we are shedding more light on the contamination and radiation issues, which are the most common causes for optical damages and laser failures in space. At first, we will present results based on the study of liquids and subsequently correlate these results to the particulates of the laser system environment. We present a model explaining how the laser beam traps contaminants against the optical surfaces and cause optical damages and the role of gravity in the process. We also report the results of the second harmonic generation efficiency for nonlinear optical crystals irradiated with high-energy beams of protons. In addition, we are proposing to employ the technique of adsorption to minimize the presence of adsorbing molecules present in the laser compartment.

Single-mode SOA-based 1kHz-linewidth dual-wavelength random fiber laser.

PubMed

Xu, Yanping; Zhang, Liang; Chen, Liang; Bao, Xiaoyi

2017-07-10

Narrow-linewidth multi-wavelength fiber lasers are of significant interests for fiber-optic sensors, spectroscopy, optical communications, and microwave generation. A novel narrow-linewidth dual-wavelength random fiber laser with single-mode operation, based on the semiconductor optical amplifier (SOA) gain, is achieved in this work for the first time, to the best of our knowledge. A simplified theoretical model is established to characterize such kind of random fiber laser. The inhomogeneous gain in SOA mitigates the mode competition significantly and alleviates the laser instability, which are frequently encountered in multi-wavelength fiber lasers with Erbium-doped fiber gain. The enhanced random distributed feedback from a 5km non-uniform fiber provides coherent feedback, acting as mode selection element to ensure single-mode operation with narrow linewidth of ~1kHz. The laser noises are also comprehensively investigated and studied, showing the improvements of the proposed random fiber laser with suppressed intensity and frequency noises.

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.

Which colors would extraterrestrial civilizations use to transmit signals?: The ;magic wavelengths; for optical SETI

NASA Astrophysics Data System (ADS)

Narusawa, Shin-ya; Aota, Tatusya; Kishimoto, Ryo

2018-04-01

In the case of radio SETI, there are predicted frequencies which extraterrestrial beings select to send messages to other civilizations. Those are called ;magic frequencies. Considering the optical region, terrestrial technologies can not transmit arbitrary wavelengths of high-power optical lasers, easily. In this article, we discuss communications among civilizations with the same level of technology as us to enhance the persuasive power. It might be possible to make a reasonable assumption about the laser wavelengths transmitted by extraterrestrial intelligences to benefit optical SETI (OSETI) methods. Therefore, we propose some ;magic wavelengths; for spectroscopic OSETI observations in this article. From the senders point of view, we argue that the most favorable wavelength used for interstellar communication would be the one of YAG lasers, at 1.064 μm or its Second Harmonic Generation (532.1 nm). On the contrary, there are basic absorption lines in the optical spectra, which are frequently observed by astrophysicists on Earth. It is possible that the extraterrestrials used lasers, which wavelengths are tuned to such absorption lines for sending messages. In that case, there is a possibility that SHG and/or Sum Frequency Generation of YAG and YLF lasers are used. We propose three lines at, 393.8 nm (near the Ca K line), 656.5 nm (near the Hα line) and 589.1 nm (Na D2 line) as the magic wavelengths.

Laser-Ranging Transponders for Science Investigations of the Moon and Mars

NASA Technical Reports Server (NTRS)

Hemmati, Hamid; Chen, Yijiang; Bimbaum, Kevin

2012-01-01

An active laser was developed ranging in real-time with two terminals, emulating interplanetary distances, and with submillimeter accuracy. In order to overcome the limitations to ranging accuracy from jitters and delay drifts within the transponders, architecture was proposed based on asynchronous paired one-way ranging with local references. A portion of the transmitted light is directed, via a reference path, to the local detector. This allows for compensation of any jitter in the timing of the emitted laser pulse. The same detector is used to measure the time of the received pulses emitted from the remote terminal. This approach removes any change in the delay caused by the detector or its electronics. Two separate terminals using commercial off-the-shelf hardware were built to emulate active laser ranging over interplanetary distances. The communication link for the command to start recording pulse arrival times and data transfer from one terminal to the other was achieved using a standard wireless link, emulating free space laser communication. The deviation is well below the goal of 1-mm precision. This leaves enough margin to achieve 1-mm precision when including the fluctuations due to atmospheric turbulence while ranging to Mars through the Earth s atmosphere. The two terminals are mounted on translation stages, which can be moved freely on rails to yield a wide range of distances with fine adjustment. The two terminals were separated by approximately 16 meters.

Technology Confronts Disasters: R and D at MIT Lincoln Laboratory Will Help Agencies Better Respond to Disasters and Humanitarian

DTIC Science & Technology

2015-07-07

communications system that might utilize balloons or unmanned aerial vehicles (UAV) when the existing communications infrastructure is damaged or destroyed in...controlled by member in the back and safely tethered to the po man in front. HADR Group 7 Laser infrared images color-calibrated to show heights or

Using an Interactive Computer Program to Communicate With the Wilderness Visitor

Treesearch

David W. Harmon

1992-01-01

The Bureau of Land Management, Oregon State Office, identified a need for a tool to communicate with wilderness visitors, managers, and decisionmakers regarding wilderness values and existing resource information in 87 wilderness study areas. An interactive computer program was developed using a portable Macintosh computer, a touch screen monitor, and laser disk player...

Fiber-laser frequency combs for the generation of tunable single-frequency laser lines, mm- and THz-waves and sinc-shaped Nyquist pulses

NASA Astrophysics Data System (ADS)

Schneider, Thomas

2015-03-01

High-quality frequency comb sources like femtosecond-lasers have revolutionized the metrology of fundamental physical constants. The generated comb consists of frequency lines with an equidistant separation over a bandwidth of several THz. This bandwidth can be broadened further to a super-continuum of more than an octave through propagation in nonlinear media. The frequency separation between the lines is defined by the repetition rate and the width of each comb line can be below 1 Hz, even without external stabilization. By extracting just one of these lines, an ultra-narrow linewidth, tunable laser line for applications in communications and spectroscopy can be generated. If two lines are extracted, the superposition of these lines in an appropriate photo-mixer produces high-quality millimeter- and THz-waves. The extraction of several lines can be used for the creation of almost-ideally sinc-shaped Nyquist pulses, which enable optical communications with the maximum-possible baud rate. Especially combs generated by low-cost, small-footprint fs-fiber lasers are very promising. However due to the resonator length, the comb frequencies have a typical separation of 80 - 100 MHz, far too narrow for the selection of single tones with standard optical filters. Here the extraction of single lines of an fs-fiber laser by polarization pulling assisted stimulated Brillouin scattering is presented. The application of these extracted lines as ultra-narrow, stable and tunable laser lines, for the generation of very high-quality mm and THz-waves with an ultra-narrow linewidth and phase noise and for the generation of sinc-shaped Nyquist pulses with arbitrary bandwidth and repetition rate is discussed.

Development of on-line laser power monitoring system

NASA Astrophysics Data System (ADS)

Ding, Chien-Fang; Lee, Meng-Shiou; Li, Kuan-Ming

2016-03-01

Since the laser was invented, laser has been applied in many fields such as material processing, communication, measurement, biomedical engineering, defense industries and etc. Laser power is an important parameter in laser material processing, i.e. laser cutting, and laser drilling. However, the laser power is easily affected by the environment temperature, we tend to monitor the laser power status, ensuring there is an effective material processing. Besides, the response time of current laser power meters is too long, they cannot measure laser power accurately in a short time. To be more precisely, we can know the status of laser power and help us to achieve an effective material processing at the same time. To monitor the laser power, this study utilize a CMOS (Complementary metal-oxide-semiconductor) camera to develop an on-line laser power monitoring system. The CMOS camera captures images of incident laser beam after it is split and attenuated by beam splitter and neutral density filter. By comparing the average brightness of the beam spots and measurement results from laser power meter, laser power can be estimated. Under continuous measuring mode, the average measuring error is about 3%, and the response time is at least 3.6 second shorter than thermopile power meters; under trigger measuring mode which enables the CMOS camera to synchronize with intermittent laser output, the average measuring error is less than 3%, and the shortest response time is 20 millisecond.

Semiconductor laser using multimode interference principle

NASA Astrophysics Data System (ADS)

Gong, Zisu; Yin, Rui; Ji, Wei; Wu, Chonghao

2018-01-01

Multimode interference (MMI) structure is introduced in semiconductor laser used in optical communication system to realize higher power and better temperature tolerance. Using beam propagation method (BPM), Multimode interference laser diode (MMI-LD) is designed and fabricated in InGaAsP/InP based material. As a comparison, conventional semiconductor laser using straight single-mode waveguide is also fabricated in the same wafer. With a low injection current (about 230 mA), the output power of the implemented MMI-LD is up to 2.296 mW which is about four times higher than the output power of the conventional semiconductor laser. The implemented MMI-LD exhibits stable output operating at the wavelength of 1.52 μm and better temperature tolerance when the temperature varies from 283.15 K to 293.15 K.

A 100 mW-level single-mode switchable dual-wavelength erbium-doped fiber laser

NASA Astrophysics Data System (ADS)

Cheng, Jianqun; Zhang, Liaolin; Sharafudeen, Kaniyarakkal; Qiu, Jianrong

2013-10-01

A switchable dual-wavelength CW erbium-doped fiber laser with two cascaded fiber Bragg gratings has been proposed and demonstrated experimentally at room temperature. The laser uses a linear resonant cavity configuration incorporating a Sagnac loop with a polarization controller (PC) and can switch flexibly to output a single wavelength or dual wavelengths based on the polarization hole burning (PHB) effect. The slope efficiency and maximum output power can reach 23% and 96 mW, respectively. The two lasing peaks of the laser, with a narrow linewidth output and an optical signal-to-noise ratio of more than 50 dB, are located in the C and L bands of the optical communication window, respectively. The laser shows good stability with respect to the wavelength and output power.

Error rate performance of atmospheric laser communication based on bubble model

NASA Astrophysics Data System (ADS)

Xu, Ke; Wang, Jin; Li, Yan

2009-08-01

Free-Space Optics (FSO) can provide an effective line-of-sight and wireless communication with high bandwidth over a short distance. As a promising field of wireless communication, FSO is being accepted as an alternative of the more expensive fiber-optic based solutions. Despite the advantages of FSO, atmospheric turbulence has a significant impact on laser beam propagating through the channel in the atmosphere over a long distance. Turbulent eddies of various size and refractive index result in intensity scintillation and phase wander, which can severely impair the quality of FSO communication system. In this paper, a new geometrical model is used to assess the effects of turbulence on laser beam in its propagation path. The atmosphere is modeled along the transmission path filled with spatial-distributed spherical bubbles. The size and refractive index discontinuity of each bubble is K-distributed. This Monte Carlo technique allows us to estimate the fluctuation of intensity and phase shifts along the path. A pair of uncollimated rays arrives at the receiver through different path, and an optical path difference is produced. This difference causes a delay between the two rays. At the receiver, as the two rays are superposed, the delay ultimately affects the judgement of the bits. In the simulation, we assume that when the delay exceeds half of the bit width, bit error is possible. On the contrary, when the delay is less than the bit width, the bit error will not happen. Based on this assumption, we calculate the BER under different conditions, and results are further analyzed.

Novel laser communications transceiver with internal gimbal-less pointing and tracking

NASA Astrophysics Data System (ADS)

Chalfant, Charles H., III; Orlando, Fred J., Jr.; Gregory, Jeff T.; Sulham, Clifford; O'Neal, Chad B.; Taylor, Geoffrey W.; Craig, Douglas M.; Foshee, James J.; Lovett, J. Timothy

2002-12-01

This paper describes a novel laser communications transceiver for use in multi-platform satellite networks or clusters that provides internal pointing and tracking technique allowing static mounting of the transceiver subsystems and minimal use of mechanical stabilization techniques. This eliminates the need for the large, power hungry, mechanical gimbals that are required for laser cross-link pointing, acquisition and tracking. The miniature transceiver is designed for pointing accuracies required for satellite cross-link distances of between 500 meters to 5000 meters. Specifically, the designs are targeting Air Force Research Lab's TechSat21 Program, although alternative transceiver configurations can provide for much greater link distances and other satellite systems. The receiver and transmitter are connected via fiber optic cabling from a separate electronics subsystem containing the optoelectronics PCBs, thereby eliminating active optoelectronic elements from the transceiver's mechanical housing. The internal acquisition and tracking capability is provided by an advanced micro-electro-mechanical system (MEMS) and an optical design that provides a specific field-of-view based on the satellite cluster's interface specifications. The acquisition & tracking control electronics will utilize conventional closed loop tracking techniques. The link optical power budget and optoelectronics designs allow use of transmitter sources with output powers of near 100 mW. The transceiver will provide data rates of up to 2.5 Gbps and operate at either 1310 nm or 1550 nm. In addition to space-based satellite to satellite cross-links, we are planning to develop a broad range of applications including air to air communications between highly mobile airborne platforms and terrestrial fixed point to point communications.

Gated high speed optical detector

NASA Technical Reports Server (NTRS)

Green, S. I.; Carson, L. M.; Neal, G. W.

1973-01-01

The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

The 10 micrometer transmitter

NASA Technical Reports Server (NTRS)

1976-01-01

The design, fabrication tests, and engineering model components of a 10.6 mum wideband transceiver system are reported. The effort emphasized the transmitter subsystem, including the development of the laser, the modulator driver, and included productization of both the transmitter and local oscillator lasers. The transmitter subsystem is functionally compatible with the receiver engineering model terminal, and has undergone high data rate communication system testing against that terminal.

Overview of the Laser Communications Relay Demonstration Project

DTIC Science & Technology

2012-06-01

and aim the very narrow beam at the ground station on earth, despite platform vibrations, motions, and distortions. When receiving, the GEO optical ...4 Figure 1- Inertially Stablized Optical Module Each optical module, shown in Figure 1, is a 4-inch reflective telescope that...6 the GEO space terminal beam pointing direction. Turbulence effects dominate the laser power required for a ground-based beacon. Turbulence

Polarization measurements through space-to-ground atmospheric propagation paths by using a highly polarized laser source in space.

PubMed

Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo

2009-12-07

The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. An existing Japanese laser communication satellite and optical ground station were used to measure Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite. As a result, the polarization was preserved within an rms error of 1.6 degrees, and the degree of polarization was 99.4+/-4.4% through the space-to-ground atmosphere. These results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography worldwide in the future.

Toward laser cooling and trapping lanthanum ions

NASA Astrophysics Data System (ADS)

Olmschenk, Steven; Banner, Patrick; Hankes, Jessie; Nelson, Amanda

2017-04-01

Trapped atomic ions are a leading candidate for applications in quantum information. For scalability and applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress toward laser cooling doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Since the hyperfine structure of this ion has not been measured, we are using optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of transitions in lanthanum. Using laser ablation to directly produce ions from a solid target, we laser cool and trap barium ions, and explore extending this technique to lanthanum ions. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Wavelength tunable ultrafast fiber laser via reflective mirror with taper structure.

PubMed

Fang, Li; Huang, Chuyun; Liu, Ting; Gogneau, Noelle; Bourhis, Eric; Gierak, Jacques; Oudar, Jean-Louis

2016-12-20

Laser sources with a controllable flexible wavelength have found widespread applications in optical fiber communication, optical sensing, and microscopy. Here, we report a tunable mode-locked fiber laser using a graphene-based saturable absorber and a tapered mirror as an end mirror in the cavity. The phase layer in the mirror is precisely etched by focused ion beam (FIB) milling technology, and the resonant wavelength of the mirror shifts correspond to the different etch depths. By scanning the tapered mirror mechanically, the center wavelength of a mode-locked fiber laser can be continuously tuned from 1562 to 1532 nm, with a pulse width in the sub-ps level and repetition rate of 27 MHz.

Simultaneous classical communication and quantum key distribution using continuous variables*

NASA Astrophysics Data System (ADS)

Qi, Bing

2016-10-01

Presently, classical optical communication systems employing strong laser pulses and quantum key distribution (QKD) systems working at single-photon levels are very different communication modalities. Dedicated devices are commonly required to implement QKD. In this paper, we propose a scheme which allows classical communication and QKD to be implemented simultaneously using the same communication infrastructure. More specially, we propose a coherent communication scheme where both the bits for classical communication and the Gaussian distributed random numbers for QKD are encoded on the same weak coherent pulse and decoded by the same coherent receiver. Simulation results based on practical system parameters show that both deterministic classical communication with a bit error rate of 10-9 and secure key distribution could be achieved over tens of kilometers of single-mode fibers. It is conceivable that in the future coherent optical communication network, QKD will be operated in the background of classical communication at a minimal cost.

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.

Intentionally Short Range Communications (ISRC)

DTIC Science & Technology

1993-05-01

ere known to the author. The first effort to develop a portable short-range communicator v, as in the carly- 1980s ( Hislop , 1982). The other was a...happenstance. The only previous effort known to the author to deliberately limit IR range was a proposal in the mid- 1980s . This attempt to develop an IR laser...B. Johnson, J. H. Yen. and G. A. Clapp. 1986. "Short-Range UV Communication Links," Proc. Tact. Comm. Conf. 1,60. Hislop , A. R. 1982. "A Head-Worn 60

InGaAs Multiple Quantum Well Modulating Retro-reflector for Free Space Optical Communications

DTIC Science & Technology

2002-01-01

PIN optical modulators grown on GaAs substrates by molecular beam epitaxy ,J. Vac Sci. B 18, 1609-16 13 (2000). Peter G. Goetz, W. S. Rabinovich...reflector is then interrogated by a cw laser beam from a conventional optical communications system and returns a modulated signal beam to the...optical communication systems. By mounting an electro-optic shutter in front of the corner- cube, the retro-reflected beam can be turned on or off (or at

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.

Small-signal modulation characteristics of a polariton laser

PubMed Central

Zunaid Baten, Md; Frost, Thomas; Iorsh, Ivan; Deshpande, Saniya; Kavokin, Alexey; Bhattacharya, Pallab

2015-01-01

Use of large bandgap materials together with electrical injection makes the polariton laser an attractive low-power coherent light source for medical and biomedical applications or short distance plastic fiber communication at short wavelengths (violet and ultra-violet), where a conventional laser is difficult to realize. The dynamic properties of a polariton laser have not been investigated experimentally. We have measured, for the first time, the small signal modulation characteristics of a GaN-based electrically pumped polariton laser operating at room temperature. A maximum −3 dB modulation bandwidth of 1.18 GHz is measured. The experimental results have been analyzed with a theoretical model based on the Boltzmann kinetic equations and the agreement is very good. We have also investigated frequency chirping during such modulation. Gain compression phenomenon in a polariton laser is interpreted and a value is obtained for the gain compression factor. PMID:26154681

Unusual scaling laws for plasmonic nanolasers beyond the diffraction limit.

PubMed

Wang, Suo; Wang, Xing-Yuan; Li, Bo; Chen, Hua-Zhou; Wang, Yi-Lun; Dai, Lun; Oulton, Rupert F; Ma, Ren-Min

2017-12-01

Plasmonic nanolasers are a new class of amplifiers that generate coherent light well below the diffraction barrier bringing fundamentally new capabilities to biochemical sensing, super-resolution imaging, and on-chip optical communication. However, a debate about whether metals can enhance the performance of lasers has persisted due to the unavoidable fact that metallic absorption intrinsically scales with field confinement. Here, we report plasmonic nanolasers with extremely low thresholds on the order of 10 kW cm -2 at room temperature, which are comparable to those found in modern laser diodes. More importantly, we find unusual scaling laws allowing plasmonic lasers to be more compact and faster with lower threshold and power consumption than photonic lasers when the cavity size approaches or surpasses the diffraction limit. This clarifies the long-standing debate over the viability of metal confinement and feedback strategies in laser technology and identifies situations where plasmonic lasers can have clear practical advantage.

Fundamental Limit of 1/f Frequency Noise in Semiconductor Lasers Due to Mechanical Thermal Noise

NASA Technical Reports Server (NTRS)

Numata, K.; Camp, J.

2011-01-01

So-called 1/f noise has power spectral density inversely proportional to frequency, and is observed in many physical processes. Single longitudinal-mode semiconductor lasers, used in variety of interferometric sensing applications, as well as coherent communications, exhibit 1/f frequency noise at low frequency (typically below 100kHz). Here we evaluate mechanical thermal noise due to mechanical dissipation in semiconductor laser components and give a plausible explanation for the widely-observed 1/f frequency noise, applying a methodology developed for fixed-spacer cavities for laser frequency stabilization. Semiconductor-laser's short cavity, small beam radius, and lossy components are expected to emphasize thermal-noise-limited frequency noise. Our simple model largely explains the different 1/f noise levels observed in various semiconductor lasers, and provides a framework where the noise may be reduced with proper design.

A Multi-Component Automated Laser-Origami System for Cyber-Manufacturing

NASA Astrophysics Data System (ADS)

Ko, Woo-Hyun; Srinivasa, Arun; Kumar, P. R.

2017-12-01

Cyber-manufacturing systems can be enhanced by an integrated network architecture that is easily configurable, reliable, and scalable. We consider a cyber-physical system for use in an origami-type laser-based custom manufacturing machine employing folding and cutting of sheet material to manufacture 3D objects. We have developed such a system for use in a laser-based autonomous custom manufacturing machine equipped with real-time sensing and control. The basic elements in the architecture are built around the laser processing machine. They include a sensing system to estimate the state of the workpiece, a control system determining control inputs for a laser system based on the estimated data and user’s job requests, a robotic arm manipulating the workpiece in the work space, and middleware, named Etherware, supporting the communication among the systems. We demonstrate automated 3D laser cutting and bending to fabricate a 3D product as an experimental result.

Fiber lasers and amplifiers for science and exploration at NASA Goddard Space Flight Center

NASA Technical Reports Server (NTRS)

Krainak, Michael A.; Abshire, James; Allan, Graham R.; Stephen Mark

2005-01-01

We discuss present and near-term uses for high-power fiber lasers and amplifiers for NASA- specific applications including planetary topography and atmospheric spectroscopy. Fiber lasers and amplifiers offer numerous advantages for both near-term and future deployment of instruments on exploration and science remote sensing orbiting satellites. Ground-based and airborne systems provide an evolutionary path to space and a means for calibration and verification of space-borne systems. We present experimental progress on both the fiber transmitters and instrument prototypes for ongoing development efforts. These near-infrared instruments are laser sounders and lidars for measuring atmospheric carbon dioxide, oxygen, water vapor and methane and a pseudo-noise (PN) code laser ranging system. The associated fiber transmitters include high-power erbium, ytterbium, neodymium and Raman fiber amplifiers. In addition, we will discuss near-term fiber laser and amplifier requirements and programs for NASA free space optical communications, planetary topography and atmospheric spectroscopy.

Laser discrimination by stimulated emission of a phosphor

NASA Technical Reports Server (NTRS)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

PubMed

Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

2015-12-28

An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

Architecture overview and data summary of a 5.4 km free-space laser communication experiment

NASA Astrophysics Data System (ADS)

Moores, John D.; Walther, Frederick G.; Greco, Joseph A.; Michael, Steven; Wilcox, William E., Jr.; Volpicelli, Alicia M.; Magliocco, Richard J.; Henion, Scott R.

2009-08-01

MIT Lincoln Laboratory designed and built two free-space laser communications terminals, and successfully demonstrated error-free communication between two ground sites separated by 5.4 km in September, 2008. The primary goal of this work was to emulate a low elevation angle air-to-ground link capable of supporting standard OTU1 (2.667 Gb/s) data formatting with standard client interfaces. Mitigation of turbulence-induced scintillation effects was accomplished through the use of multiple small-aperture receivers and novel encoding and interleaver hardware. Data from both the field and laboratory experiments were used to assess link performance as a function of system parameters such as transmitted power, degree of spatial diversity, and interleaver span, with and without forward error correction. This work was sponsored by the Department of Defense, RRCO DDR&E, under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions and recommendations are those of the authors and are not necessarily endorsed by the United States Government.

InGaAs multiple quantum well modulating retro-reflector for free-space optical communications

NASA Astrophysics Data System (ADS)

Rabinovich, William S.; Gilbreath, G. Charmaine; Goetz, Peter G.; Mahon, Rita; Katzer, D. Scott; Ikossi-Anastasiou, Kiki; Binari, Steven C.; Meehan, Timothy J.; Stell, Mena F.; Sokolsky, Ilene; Vasquez, John A.; Vilcheck, Michael J.

2002-01-01

Modulating retro-reflectors provide means for free space optical communication without the need for a laser, telescope or pointer tracker on one end of the link. These systems work by coupling a retro-reflector with an electro- optic shutter. The modulating retro-reflector is then interrogated by a cw laser beam from a conventional optical communications system and returns a modulated signal beam to the interrogator. Over the last few years the Naval Research Laboratory has developed modulating retro-reflector based on corner cubes and large area Transmissive InGaAs multiple quantum well modulators. These devices can allow optical links at speeds up to about 10 Mbps. We will discuss the critical performance characteristics of such systems including modulating rate, power consumption, optical contrast ratio and operating wavelength. In addition a new modulating retro-reflector architecture based upon cat s eye retroreflectors will be discussed. This architecture has the possibility for data rates of hundreds of megabits per second at power consumptions below 100 mW.

Accelerator on a Chip

DOE Office of Scientific and Technical Information (OSTI.GOV)

England, Joel

2014-06-30

SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

Accelerator on a Chip

ScienceCinema

England, Joel

2018-01-16

SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

Holographic Plossl Retroreflectors

NASA Technical Reports Server (NTRS)

Waluschka, Eugene

2006-01-01

Holographic retroreflectors that function equivalently to Plossl eyepieces have been developed and used in free-space optical communication systems that utilize laser beams. Plossl eyepieces are well known among telescope designers. They have been adopted for use a retroreflectors and as focusing elements (for reception) and collimating elements (for transmission) in optical communication systems. A retro-reflector that incorporates a Plossl eyepiece is termed a cat's-eye retroreflector.

Impact of atmospheric anisoplanaticity on earth-to-satellite time transfer over laser communication links

NASA Astrophysics Data System (ADS)

Belmonte, Aniceto; Taylor, Michael T.; Hollberg, Leo; Kahn, Joseph M.

2017-02-01

The need for an accurate time and position reference on orbiting platforms motivates the study of time transfer over satellite optical communication links. The transfer of precise optical clock signals to space would benefit many fields in fundamental science and applications. However, the precise role of atmospheric turbulence during the optical time transfer process is not well-known and documented. In free-space optical links, atmospheric turbulence represents a major impairment, since it causes degradation of the spatial and temporal coherence of the optical signals. We present possible link scenarios in which the atmospheric channel behavior for time transfer between ground and space can be investigated, and have identified the major challenges to be overcome. We found in our analysis that, despite the limited reciprocity in uplink and downlink propagation, partial two-way cancellation of atmospheric effects still occurs. We established that laser communication links make possible high-quality time transfer in most practical propagation scenarios and over a single satellite visibility period. Our results demonstrate that sharing of optical communication resources for optical time transfer and range determination is an effective and relevant scheme for space clock developments and enabling for future space missions.

Rugged TDLAS system for High Energy Laser atmospheric propagation characterization

NASA Astrophysics Data System (ADS)

Perram, Glen; Rice, Christopher

2008-10-01

An active remote sensing instrument for the characterization of atmospheric absorption, scattering, and scintillation at several key high energy laser wavelengths is in development. The instrument is based on narrow band tunable diode lasers fiber coupled to a 12'' Ritchey-Chretien transmit telescope and a second receive telescope with visible or near infrared imager. For example, tunable diode lasers have been used to obtain absorption spectra in the laboratory for the Cs D2 lines near 852 nm and the oxygen X-b lines near 760 nm, key to the Diode Pumped Alkali Laser (DPAL) concept. Absorbencies of less than 0.5% are observable. Applications will be assessed including effects to HEL atmospheric propagation from molecular and aerosol absorption and scattering, Cn2 estimation from atmospheric turbulence, hazardous chemical emission detection, and laser communication interception from side scattering. The system will soon be deployed to a military laser test range to characterize path lengths of greater than 1 km.

Direct solar pumping of semiconductor lasers: A feasibility study

NASA Technical Reports Server (NTRS)

Anderson, Neal G.

1991-01-01

The primary goals of the feasibility study are the following: (1) to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space directly focused sunlight; and (2) to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or battery electrically pumping a current injection laser. With external modulation, such lasers may prove to be efficient sources for intersatellite communications. We proposed to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation for operation at low pump intensities. This report outlines our progress toward these goals. Discussion of several technical details are left to the attached summary abstract.

Orbital Angular Momentum Multiplexing over Visible Light Communication Systems

NASA Astrophysics Data System (ADS)

Tripathi, Hardik Rameshchandra

This thesis proposes and explores the possibility of using Orbital Angular Momentum multiplexing in Visible Light Communication system. Orbital Angular Momentum is mainly applied for laser and optical fiber transmissions, while Visible Light Communication is a technology using the light as a carrier for wireless communication. In this research, the study of the state of art and experiments showing some results on multiplexing based on Orbital Angular Momentum over Visible Light Communication system were done. After completion of the initial stage; research work and simulations were performed on spatial multiplexing over Li-Fi channel modeling. Simulation scenarios which allowed to evaluate the Signal-to-Noise Ratio, Received Power Distribution, Intensity and Illuminance were defined and developed.

Utility of optical facial feature and arm movement tracking systems to enable text communication in critically ill patients who cannot otherwise communicate.

PubMed

Muthuswamy, M B; Thomas, B N; Williams, D; Dingley, J

2014-09-01

Patients recovering from critical illness especially those with critical illness related neuropathy, myopathy, or burns to face, arms and hands are often unable to communicate by writing, speech (due to tracheostomy) or lip reading. This may frustrate both patient and staff. Two low cost movement tracking systems based around a laptop webcam and a laser/optical gaming system sensor were utilised as control inputs for on-screen text creation software and both were evaluated as communication tools in volunteers. Two methods were used to control an on-screen cursor to create short sentences via an on-screen keyboard: (i) webcam-based facial feature tracking, (ii) arm movement tracking by laser/camera gaming sensor and modified software. 16 volunteers with simulated tracheostomy and bandaged arms to simulate communication via gross movements of a burned limb, communicated 3 standard messages using each system (total 48 per system) in random sequence. Ten and 13 minor typographical errors occurred with each system respectively, however all messages were comprehensible. Speed of sentence formation ranged from 58 to 120s with the facial feature tracking system, and 60-160s with the arm movement tracking system. The average speed of sentence formation was 81s (range 58-120) and 104s (range 60-160) for facial feature and arm tracking systems respectively, (P<0.001, 2-tailed independent sample t-test). Both devices may be potentially useful communication aids in patients in general and burns critical care units who cannot communicate by conventional means, due to the nature of their injuries. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Scintillation index of higher order mode laser beams in strong turbulence

NASA Astrophysics Data System (ADS)

Baykal, Yahya

2017-03-01

The scintillation index of higher order laser modes is examined in strong atmospheric turbulence. In our formulation, modified Rytov theory is employed with the inclusion of existing modified turbulence spectrum which presents the atmospheric turbulence spectrum as a linear filter having refractive and diffractive spatial frequency cutoffs. Variations of the scintillation index in strong atmospheric turbulence are shown against the weak turbulence plane wave scintillation index for various higher order laser modes of different sizes. Use of higher order modes in optical wireless communication links operating in strongly turbulent atmosphere is found to be advantageous in reducing the scintillation noise.

Few-mode vertical-cavity surface-emitting laser: Optional emission of transverse modes with different polarizations

NASA Astrophysics Data System (ADS)

Zhong, Chuyu; Zhang, Xing; Hofmann, Werner; Yu, Lijuan; Liu, Jianguo; Ning, Yongqiang; Wang, Lijun

2018-05-01

Few-mode vertical-cavity surface-emitting lasers that can be controlled to emit certain modes and polarization states simply by changing the biased contacts are proposed and fabricated. By directly etching trenches in the p-doped distributed Bragg reflector, the upper mesa is separated into several submesas above the oxide layer. Individual contacts are then deposited. Each contact is used to control certain transverse modes with different polarization directions emitted from the corresponding submesa. These new devices can be seen as a prototype of compact laser sources in mode division multiplexing communications systems.

Narrowband 1.5-{mu}m Bragg filter based on a polymer waveguide with a laser-written refractive-index grating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, Viktor I; Panchenko, Vladislav Ya; Seminogov, V N

We report the fabrication of narrowband frequency-selective filters for the 1.5-{mu}m telecom window, which include a single-mode polymer waveguide with a submicron Bragg grating inscribed by a helium-cadmium laser. The filters have a reflectance R > 98 % and a nearly rectangular reflection band with a bandwidth {Delta}{lambda}{approx}0.4nm. They can be used as components of optical multiplexers/demultiplexers for combining and separating signals in high-speed dense wavelength-division multiplexed optical fibre communication systems. (laser components)

Narrow spectral linewidth in InAs/InP quantum dot distributed feedback lasers

NASA Astrophysics Data System (ADS)

Duan, J.; Huang, H.; Lu, Z. G.; Poole, P. J.; Wang, C.; Grillot, F.

2018-03-01

This paper reports on the spectral linewidth of InAs/InP quantum dot distributed feedback lasers. Owing to a low inversion factor and a low linewidth enhancement factor, a narrow spectral linewidth of 160 kHz (80 kHz intrinsic linewidth) with a low sensitivity to temperature is demonstrated. When using anti-reflection coatings on both facets, narrow linewidth operation is extended to high powers, believed to be due to a reduction in the longitudinal spatial hole burning. These results confirm the high potential of quantum dot lasers for increasing transmission capacity in future coherent communication systems.

Future Optical Communications Systems

DTIC Science & Technology

2008-06-01

rich handsets are driving growth in the wireless backhaul market. Both the iPhone and Blackberry are growing in popularity. Figure 49 forecasts the...electronic emission and tunneling , and hetero-barrier leakage. In barrier thermo-electronic emission, the conduction band of the quantum well laser is...barrier can reduce the mod- ulation bandwidth of the laser and reduce high-temperature performance due to tunneling out of the p-n junction or due

Robotic Vehicle Communications Interoperability

DTIC Science & Technology

1988-08-01

starter (cold start) X X Fire suppression X Fording control X Fuel control X Fuel tank selector X Garage toggle X Gear selector X X X X Hazard warning...optic Sensors Sensor switch Video Radar IR Thermal imaging system Image intensifier Laser ranger Video camera selector Forward Stereo Rear Sensor control...optic sensors Sensor switch Video Radar IR Thermal imaging system Image intensifier Laser ranger Video camera selector Forward Stereo Rear Sensor

Environmental Impact Analysis Process. Environmental Review Starlab Site On Ascension Island

DTIC Science & Technology

1990-08-28

IRPA International Radiation Protection Association Km kilometer LMSC Lockheed Missile and Space Company M meter MPE Maximum permissible exposure...amended does not apply to ascension island [J. Sheppard USFWS, Washington, D.C. personal communication to R. Kroodsma, Oak Ridge National Laboratory...HUMAN HEALTH AND SAFTEY Under operating plans, no human exposure to laser light is likely to occur. However, laser light exposure to humans at

Chalcogenide Glass Lasers on Silicon Substrate Integrated Photonics

DTIC Science & Technology

2016-07-08

AFRL-AFOSR-UK-TR-2016-0013 Chalcogenide glass lasers on silicon substrate integrated photonics Clara Dimas MASDAR INSTITUTE OF SCIENCE & TECHNOLOGY...PROJECT NUMBER 5e.  TASK NUMBER 5f.  WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) MASDAR INSTITUTE OF SCIENCE & TECHNOLOGY - MIST...communication by reducing coupling losses, chip size, energy requirements and manufacturing cost. Chalcogenide glass (ChG) light sources doped with rare earth

Measurement of laser spot quality

NASA Technical Reports Server (NTRS)

Milster, T. D.; Treptau, J. P.

1991-01-01

Several ways of measuring spot quality are compared. We examine in detail various figures of merit such as full width at half maximum (FWHM), full width at 1/(e exp 2) maximum, Strehl ratio, and encircled energy. Our application is optical data storage, but results can be applied to other areas like space communications and high energy lasers. We found that the optimum figure of merit in many cases is Strehl ratio.

Mid-infrared transmitter and receiver modules for free-space optical communication.

PubMed

Hao, Qiang; Zhu, Guoshen; Yang, Song; Yang, Kangwen; Duan, Tao; Xie, Xiaoping; Huang, Kun; Zeng, Heping

2017-03-10

We report on the experimental implementation of single-frequency fiber-laser pumped mid-infrared (mid-IR) transmitter and receiver modules for free-space communications. These modules enable frequency upconversion and downconversion between the 1550-nm telecom wavelength and the mid-IR, thus providing essential free-space transmission links with mid-IR single-frequency lasers in the 3.6 μm region. Specifically, based on difference frequency generation (DFG) in MgO-doped periodically poled LiNbO₃ (MgO:PPLN), the mid-IR transmitter produces 9.3-mW power at 3594 nm with 5-W pump power at 1083 nm (<10  kHz linewidth) and 3-W signal power at 1550 nm (<10  kHz linewidth), and the mid-IR receiver reproduces 12-μW power at 1550 nm with 4.7-W pump power at 1083 nm and 5-mW laser at 3594 nm. The whole modules are integrated into portable and compact devices by incorporating single-frequency fiber lasers, fiber amplifiers, DFG units, and related electronic circuits. In addition, the uses of all polarization-maintaining fiber configuration and well-controlled heat dissipation make the mid-IR transmitter and receiver exhibit a long-term stability.

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.

Diode lasers: From laboratory to industry

NASA Astrophysics Data System (ADS)

Nasim, Hira; Jamil, Yasir

2014-03-01

The invention of first laser in 1960 triggered the discovery of several new families of lasers. A rich interplay of different lasing materials resulted in a far better understanding of the phenomena particularly linked with atomic and molecular spectroscopy. Diode lasers have gone through tremendous developments on the forefront of applied physics that have shown novel ways to the researchers. Some interesting attributes of the diode lasers like cost effectiveness, miniature size, high reliability and relative simplicity of use make them good candidates for utilization in various practical applications. Diode lasers are being used by a variety of professionals and in several spectroscopic techniques covering many areas of pure and applied sciences. Diode lasers have revolutionized many fields like optical communication industry, medical science, trace gas monitoring, studies related to biology, analytical chemistry including elemental analysis, war fare studies etc. In this paper the diode laser based technologies and measurement techniques ranging from laboratory research to automated field and industry have been reviewed. The application specific developments of diode lasers and various methods of their utilization particularly during the last decade are discussed comprehensively. A detailed snapshot of the current state of the art diode laser applications is given along with a detailed discussion on the upcoming challenges.

Parametric study of intersatellite CO2 laser data links

NASA Astrophysics Data System (ADS)

Bonek, E.; Lutz, H.

The performance capability of current CO2 laser communication tecnology for intersatellite data links is evaluated. The link parameters, such as the distance, bit rate, ac signal-to-noise ratio, are related to the masses and the prime power requirements of satellite laser terminals using variables like the telescope (antenna) aperture diameter and the transmitted laser power. It is found that high data rates could be readily transmitted with telescopes of the order of only 10 cm in diameter, with the complte laser data terminals weighing between 25 kg and 70 kg and consuming prime power in the 90-300 W range. In addition, these terminals would require only about 0.1 cu m or less of volume and a very low movable antenna mass, which would alleviate constraints on satellite attitude control units in remote sensing missions.

Nonlinear Optics and Applications

NASA Technical Reports Server (NTRS)

Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

2007-01-01

Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

Vertically Emitting Indium Phosphide Nanowire Lasers.

PubMed

Xu, Wei-Zong; Ren, Fang-Fang; Jevtics, Dimitars; Hurtado, Antonio; Li, Li; Gao, Qian; Ye, Jiandong; Wang, Fan; Guilhabert, Benoit; Fu, Lan; Lu, Hai; Zhang, Rong; Tan, Hark Hoe; Dawson, Martin D; Jagadish, Chennupati

2018-06-13

Semiconductor nanowire (NW) lasers have attracted considerable research effort given their excellent promise for nanoscale photonic sources. However, NW lasers currently exhibit poor directionality and high threshold gain, issues critically limiting their prospects for on-chip light sources with extremely reduced footprint and efficient power consumption. Here, we propose a new design and experimentally demonstrate a vertically emitting indium phosphide (InP) NW laser structure showing high emission directionality and reduced energy requirements for operation. The structure of the laser combines an InP NW integrated in a cat's eye (CE) antenna. Thanks to the antenna guidance with broken asymmetry, strong focusing ability, and high Q-factor, the designed InP CE-NW lasers exhibit a higher degree of polarization, narrower emission angle, enhanced internal quantum efficiency, and reduced lasing threshold. Hence, this NW laser-antenna system provides a very promising approach toward the achievement of high-performance nanoscale lasers, with excellent prospects for use as highly localized light sources in present and future integrated nanophotonics systems for applications in advanced sensing, high-resolution imaging, and quantum communications.

Theoretical analyses of a 1.617-μm laser with a MOPA configuration

NASA Astrophysics Data System (ADS)

Cai, He; Han, Juhong; Wang, You; Rong, Kepeng; Yu, Hang; Wang, Shunyan; An, Guofei; Zhang, Wei; Wu, Peng; Yu, Qiang; Wang, Hongyuan

2018-01-01

In the recent years, lasers around 1.6 μm are attracted much attention since their wavelengths fit the atmospheric transmission window and can be used for applications in a range of fields including laser radar, gas sensing, and free-space communications. As one of the lasing wavelengths of an Er:YAG medium is just located in the 1.6 μm region, such a laser has been gaining more and more extensive applications in the near infrared. Until now, rare literatures have been found in the MOPA (Master Oscillator Power Amplifier) study of a 1.617 μm Er:YAG laser because the effect of upconversion will become greater while a higher doping concentration is adopted. In this study, we theoretically analyze the amplification features of a 1.617 μm Er:YAG seed laser by using a multiple MOPA configuration. In the simulation, a kinetic model is established to investigate how the doping concentration, crystal length, and pump power affect the amplification efficiency of a seed laser. The results would be helpful to construct a feasible 1.617 μm laser system.

Evolution of the Intelligent Telecommunications Network.

ERIC Educational Resources Information Center

Mayo, John S.

1982-01-01

Discusses the evolution of the nationwide telecommunications network, including key technologies (transistors, communications satellites, and lasers), putting these technologies together, current and future services, and challenges for the future. (JN)

Solid state laser communications in space (SOLACOS) high data rate satellite communication system verification program

NASA Astrophysics Data System (ADS)

Pribil, Klaus; Flemmig, Joerg

1994-09-01

This paper gives an overview on the current development status of the SOLACOS program and presents the highlights of the program. SOLACOS (Solid State Laser Communications in Space) is the national German program to develop a high performance laser communication system for high data rate transmission between LEO and GEO satellites (Inter Orbit Link, IOL). Two experimental demonstrator terminals are designed and developed in the SOLACOS program. The main development objectives are the Pointing Acquisition and Tracking subsystem (PAT) and the high data rate communication system. All key subsystems and components are straightway developed to be upgraded in follow- on projects to full space qualification. The main design objective for the system is a high degree of modularity which allows to easily upgrade the system with new upcoming technologies. Therefore, all main subsystems are interconnected via fibers to ease replacement of subsystems. The system implements an asymmetric data link with a 650 MBit/s return channel and a 10 MBit/s forward channel. The 650 MBit/s channel is based on a diode pumped Nd:YAG, Integrated Optics Modulator and uses the syncbit transmission scheme. In the syncbit system synchronization information which is necessary to maintain phase lock of the local oscillator of the coherent receiver is transmitted time multiplexed into the data stream. The PAT system comprises two beam detection sensors and three beam steering elements. For initial acquisition and tracking of the remote satellite a high speed CCD camera with an integrated image processing unit, the Acquisition and Tracking Sensor (ATS) is used. In the tacking mode the beam position is sensed via the Fibernutator sensor which is also used to couple the incoming signal into the receiver fiber. Incoming and outgoing beams are routed through the telescopes which are positioned with a 2 axis gimbal mechanism and a high speed beam steering mirror. The PAT system is controlled by a digital signal processor. For beam control advanced PAT algorithms are under development.

Laser-Camera Vision Sensing for Spacecraft Mobile Robot Navigation

NASA Technical Reports Server (NTRS)

Maluf, David A.; Khalil, Ahmad S.; Dorais, Gregory A.; Gawdiak, Yuri

2002-01-01

The advent of spacecraft mobile robots-free-flyng sensor platforms and communications devices intended to accompany astronauts or remotely operate on space missions both inside and outside of a spacecraft-has demanded the development of a simple and effective navigation schema. One such system under exploration involves the use of a laser-camera arrangement to predict relative positioning of the mobile robot. By projecting laser beams from the robot, a 3D reference frame can be introduced. Thus, as the robot shifts in position, the position reference frame produced by the laser images is correspondingly altered. Using normalization and camera registration techniques presented in this paper, the relative translation and rotation of the robot in 3D are determined from these reference frame transformations.