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Sample records for all-optical format conversion

  1. All-optical format conversion using a periodically poled lithium niobate waveguide and a reflective semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Sun, Junqiang; Sun, Qizhen; Wang, Dalin; Zhou, Minjuan; Zhang, Xinliang; Huang, Dexiu; Fejer, M. M.

    2007-07-01

    In the present letter, the authors report on the realization of all-optical format conversion by using the cascaded sum- and difference-frequency generation in a periodically poled lithium niobate waveguide and the active mode locking in a reflective-semiconductor-optical-amplifier-based fiber ring laser. Tunable format conversions from nonreturn-to-zero pseudorandom binary sequence (PRBS) signal to return-to-zero PRBS idler at 10 and 20Gbit/s are observed in the experiment.

  2. All-optical RZ-OOK to NRZ-OOK format conversion based on two-ring resonators

    NASA Astrophysics Data System (ADS)

    Dong, Xiaowei; Guo, Pan; Xie, Yuan

    2015-01-01

    Based on spectral shaping principle, we propose a novel all-optical return-to-zero (RZ) to non-return-to-zero (NRZ) on-off-keying (OOK) format converter based on two-ring resonators. Influences of the coupling coefficients and loss on the spectral responses of two-ring resonators are investigated detailedly. Results demonstrated that good conversion performance can be achieved by suppressing the sideband spikes and narrowing the spectral outline of injected RZ-OOK signal. In addition, our two-ring resonators can convert RZ-OOK signals with variable duty-cycles (33%, 50%, 67%) to NRZ-OOK format with larger eye-opening extinction ratio, which makes it much feasible for interfacing different parts of future optical networks.

  3. All-optical NRZ-to-RZ data format conversion with optically injected laser diode or semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-09-01

    By injecting the optical NRZ data into a Fabry-Perot laser diode (FPLD) synchronously modulated at below threshold condition or a semiconductor optical amplifier (SOA) gain-depleted with a backward injected clock stream, the all-optical non-return to zero (NRZ) to return-to-zero (RZ) format conversion of a STM-64 date-stream for synchronous digital hierarchy (SDH) or an OC-192 data stream for synchronous optical network (SONET) in high-speed fiber-optic communication link can be performed. Without the assistance of any complicated RF electronic circuitry, the output RZ data-stream at bit rate of up to 10 Gbit/s is successfully transformed in the optically NRZ injection-locked FPLD, in which the incoming NRZ data induces gain-switching of the FPLD without DC driving current or at below threshold condition. A power penalty of 1.2 dB is measured after NRZ-to-RZ transformation in the FPLD. Alternatively, the all-optical 10Gbits/s NRZ-to-RZ format conversion can also be demonstrated in a semiconductor optical amplifier under a backward dark-optical-comb injection with its duty-cycle 70%, which is obtained by reshaping from the received data clock at 10 GHz. The incoming optical NRZ data-stream is transformed into a pulsed RZ data-stream with its duty-cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. In contrast to the FPLD, the SOA based NRZ-to-RZ converter exhibits an enhanced extinction ratio from 7 to 13 dB, and BER of 10 -13 at -18.5 dBm. In particular, the power penalty of the received RZ data-stream has greatly improved by 5 dB as compared to that obtained from FPLD.

  4. All-optical clock recovery from 10-Gb/s NRZ data and NRZ to RZ format conversion

    NASA Astrophysics Data System (ADS)

    Yin, Lina; Yan, Yumei; Zhou, Yunfeng; Wu, Jian; Lin, Jintong

    2006-01-01

    A non-return-to-zero (NRZ) to pseudo-return-to-zero (PRZ) converter consisting of a semiconductor optical amplifier (SOA) and an arrayed waveguide grating (AWG) is proposed, by which the enhancement of clock frequency component and clock-to-data suppression ratio of the NRZ data are evidently achieved. All-optical clock recovery from NRZ data at 10 Gb/s is successfully demonstrated with the proposed NRZ-to-PRZ converter and a mode-locked SOA fiber laser. Furthermore, NRZ-to-RZ format conversion of 10 Gb/s is realized by using the recovered clock as the control light of terahertz optical asymmetric demultiplexer (TOAD), which further proves that the proposed clock recovery scheme is applicable.

  5. All-optical 40 Gbit/s data format conversion between RZ and NRZ using a fiber delay interferometer and a single SOA

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Xu, Enming; Yu, Yu; Zhang, Yin

    2011-12-01

    We demonstrated experimentally 40 Gbit/s all-optical format conversions between return-to-zero (RZ) and nonreturn-to- zero (NRZ) using a fiber delay interferometer (FDI) and a single semiconductor optical amplifier (SOA). Firstly, 40 Gbit/s data format conversion from RZ to NRZ is realized using a FDI with temperature control and an optical bandpass filter (BPF). Then, 40 Gbit/s data format conversion from NRZ to RZ is implemented, using four-wave mixing (FWM) effect of SOA, by injecting synchronously NRZ signal and clock pulses into a single SOA. Presented method has some distinct advantages including multi-channel parallel processing, easy integration, convenient tuning, good stability, and so on, which has potential to be used in future optical networks that could combine wavelength division multiplexing (WDM) and optical time domain multiplexing (OTDM) transmission techniques.

  6. All-optical wavelength conversion for mode division multiplexed superchannels.

    PubMed

    Gong, Jiaxin; Xu, Jing; Luo, Ming; Li, Xiang; Qiu, Ying; Yang, Qi; Zhang, Xinliang; Yu, Shaohua

    2016-04-18

    We report in this work the first all-optical wavelength conversion (AOWC) of a mode division multiplexed (MDM) superchannel consisting of 2N modes by dividing the superchannel into N single-mode (SM) tributaries, wavelength converting N SM signals using well developed SM-AOWC techniques, and finally combining the N SM tributaries back to an MDM superchannel at the converted wavelength, inspired by the idea of using SM filtering techniques to filter multimode signals in astronomy. The conversions between multimode and SM are realized by 3D laser-writing photonic lanterns and SM-AOWCs are realized based on polarization insensitive four wave mixing (FWM) configuration in N semiconductor optical amplifiers (SOAs). As a proof of concept demonstration, the conversion of a 6-mode MDM superchannel with each mode modulated with orthogonal frequency division multiplexed (OFDM) quadrature phase-shift keying (QPSK)/16 quadrature amplitude modulation (QAM) signals is demonstrated in this work, indicating that the scheme is transparent to data format, polarization and compatible with multi-carrier signals. Data integrity of the converted superchannel has been verified by using coherent detection and digital signal processing (DSP). Bit error rates (BERs) below the forward error correction (FEC) hard limit (3.8 × 10-3) have been obtained for QPSK modulation at a net bitrate of 104.2 Gbit/s and BERs below the soft decision FEC threshold (1.98 × 10-2) have been achieved for 16-QAM format, giving a total aggregate bit rate of 185.8 Gbit/s when taking 20% coding overhead into account. Add and drop functionalities that usually come along with wavelength conversion in flexible network nodes have also been demonstrated. The working conditions of the SOAs, especially the pump and signal power levels, are critical for the quality of the converted signal and have been thoroughly discussed. The impact of imbalanced FWM conversion efficiency among different SM

  7. On-Chip All-Optical Passive 3.55 Gbit/s NRZ-to-PRZ Format Conversion Using a High-Q Silicon-Based Microring Resonator

    NASA Astrophysics Data System (ADS)

    Zhai, Yao; Chen, Shao-Wu; Ren, Guang-Hui

    2010-10-01

    We report the experimental result of all-optical passive 3.55 Gbit/s non-return-to-zero (NRZ) to pseudo-return-to-zero (PRZ) format conversion using a high-quality-factor (Q-factor) silicon-based microring resonator notch filter on chip. The silicon-based microring resonator has 23800 Q-factor and 22 dB extinction ratio (ER), and the PRZ signals has about 108ps width and 4.98 dB ER.

  8. 10Gbit/s all-optical NRZ to RZ conversion based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Yin, Lina; Zhou, Yunfeng; Liu, Guoming; Wu, Jian; Lin, Jintong

    2006-01-01

    Future network will include wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) technologies. All-optical format conversion between their respective preferable data formats, non-return-to-zero (NRZ) and return-to-zero (RZ), may become an important technology. In this paper, 10Gbit/s all-optical NRZ-to-RZ conversion is demonstrated based on terahertz optical asymmetric demultiplexer (TOAD) using clock all-optically recovered from the NRZ signal for the first time. The clock component is enhanced in an SOA and the pseudo-return-to-zero (PRZ) signal is filtered. The PRZ signal is input into an injection mode-locked fiber ring laser for clock recovery. The recovered clock and the NRZ signal are input into TOAD as pump signal and probe signal, respectively, and format conversion is performed. The quality of the converted RZ signal is determined by that of the recovered clock and the NRZ signal, whereas hardly influenced by gain recovery time of the SOA. In the experimental demonstration, the obtained RZ signal has an extinction ratio of 8.7dB and low pattern dependency. After conversion, the spectrum broadens obviously and shows multimode structure with spectrum interval of 0.08nm, which matches with the bit rate 10Gbit/s. Furthermore, this format conversion method has some tolerance on the pattern dependency of the clock signal.

  9. Polarization insensitive all-optical wavelength conversion of polarization multiplexed signals using co-polarized pumps.

    PubMed

    Anthur, Aravind P; Zhou, Rui; O'Duill, Sean; Walsh, Anthony J; Martin, Eamonn; Venkitesh, Deepa; Barry, Liam P

    2016-05-30

    We study and experimentally validate the vector theory of four-wave mixing (FWM) in semiconductor optical amplifiers (SOA). We use the vector theory of FWM to design a polarization insensitive all-optical wavelength converter, suitable for advanced modulation formats, using non-degenerate FWM in SOAs and parallelly polarized pumps. We demonstrate the wavelength conversion of polarization-multiplexed (PM)-QPSK, PM-16QAM and a Nyquist WDM super-channel modulated with PM-QPSK signals at a baud rate of 12.5 GBaud, with total data rates of 50 Gbps, 100 Gbps and 200 Gbps respectively. PMID:27410100

  10. All-optical wavelength conversion of a 100-Gb/s polarization-multiplexed signal.

    PubMed

    Martelli, P; Boffi, P; Ferrario, M; Marazzi, L; Parolari, P; Siano, R; Pusino, V; Minzioni, P; Cristiani, I; Langrock, C; Fejer, M M; Martinelli, M; Degiorgio, V

    2009-09-28

    We present the results of an in-depth experimental investigation about all-optical wavelength conversion of a 100-Gb/s polarization-multiplexed (POLMUX) signal. Each polarization channel is modulated at 25 Gbaud by differential quadrature phase-shift keying (DQPSK). The conversion is realized exploiting the high nonlinear chi((2)) coefficient of a periodically poled lithium niobate waveguide, in a polarization-independent configuration. We find that slight non-idealities in the polarization independent setup of the wavelength converter can significantly impair the performance of POLMUX systems. We show that high-quality wavelength conversion can be nevertheless achieved for both the polarization channels, provided that an accurate optimization of the setup is performed. This is the first demonstration, to the best of our knowledge, of the possibility to obtain penalty-free all-optical wavelength conversion in a 100-Gb/s POLMUX transmission system using direct-detection. PMID:19907562

  11. All-Optical Wavelength Conversion by Picosecond Burst Absorption in Colloidal PbS Quantum Dots.

    PubMed

    Geiregat, Pieter; Houtepen, Arjan J; Van Thourhout, Dries; Hens, Zeger

    2016-01-26

    All-optical approaches to change the wavelength of a data signal are considered more energy- and cost-effective than current wavelength conversion schemes that rely on back and forth switching between the electrical and optical domains. However, the lack of cost-effective materials with sufficiently adequate optoelectronic properties hampers the development of this so-called all-optical wavelength conversion. Here, we show that the interplay between intraband and band gap absorption in colloidal quantum dots leads to a very strong and ultrafast modulation of the light absorption after photoexcitation in which slow components linked to exciton recombination are eliminated. This approach enables all-optical wavelength conversion at rates matching state-of-the-art convertors in speed, yet with cost-effective solution-processable materials. Moreover, the stronger light-matter interaction allows for implementation in small-footprint devices with low switching energies. Being a generic property, the demonstrated effect opens a pathway toward low-power integrated photonics based on colloidal quantum dots as the enabling material. PMID:26692112

  12. All-optical analog-to-digital conversion scheme based on Sagnac loop and balanced receivers.

    PubMed

    Xu, Kun; Niu, Jian; Dai, Yitang; Sun, Xiaoqiang; Dai, Jian; Wu, Jian; Lin, Jintong

    2011-05-10

    An all-optical analog-to-digital conversion scheme based on a Sagnac loop and balanced receivers is proposed and experimentally demonstrated. Adjustable phase shift about the transfer function of the Sagnac loop is obtained by using the multiwavelength optical pulses to realize the phase-shift optical quantization. Benefit from the complementary outputs at the transmitted and reflected ports of the Sagnac loop and balanced receiver can be used to obtain the quantized output binary signal for the encoding operation. A proof-of-concept experiment is implemented using a wavelength tunable continuous-wave laser diode. Using 16 different wavelengths, the 16 quantization levels are demonstrated and an effective number of bits (ENOB) of 4 bits is obtained. PMID:21556099

  13. Ultrafast and bias-free all-optical wavelength conversion using III-V-on-silicon technology.

    PubMed

    Kumar, Rajesh; Spuesens, Thijs; Mechet, Pauline; Kumar, Pragati; Raz, Oded; Olivier, Nicolas; Fedeli, Jean-Marc; Roelkens, Gunther; Baets, Roel; Van Thourhout, Dries; Morthier, Geert

    2011-07-01

    Using a 7.5 μm diameter disk fabricated with III-V-on-silicon fabrication technology, we demonstrate bias-free all-optical wavelength conversion for non-return-to-zero on-off keyed pseudorandom bit sequence (PRBS) data at the speed of 10 Gbits/s with an extinction ratio of more than 12 dB. The working principle of such a wavelength converter is based on free-carrier-induced refractive index modulation in a pump-probe configuration. We believe it to be the first bias-free on-chip demonstration of all-optical wavelength conversion using PRBS data. All-optical gating measurements in the pump-probe configuration with the same device have revealed that it is possible to achieve wavelength conversion beyond 20 Gbits/s. PMID:21725441

  14. All-optical multi-channel wavelength conversion of Nyquist 16 QAM signal using a silicon waveguide.

    PubMed

    Long, Yun; Liu, Jun; Hu, Xiao; Wang, Andong; Zhou, Linjie; Zou, Kaiheng; Zhu, Yixiao; Zhang, Fan; Wang, Jian

    2015-12-01

    We experimentally demonstrate on-chip all-optical multi-channel wavelength conversion of Nyquist 16 ary quadrature amplitude modulation (16 QAM) signal in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼2  dB. The observed constellations of converted idlers indicate favorable performance of silicon-waveguide-based multi-channel wavelength conversion. We also experimentally study and compare the phase-conjugated wavelength conversion by degenerate four-wave mixing (FWM) and transparent wavelength conversion by non-degenerate FWM in the silicon waveguide. PMID:26625029

  15. All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

    PubMed

    Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

    2016-09-01

    We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion. PMID:27607638

  16. An integrable high resolution all-optical analog-to-digital conversion scheme

    NASA Astrophysics Data System (ADS)

    Wei, Shile; Jian, Wu; Zhao, Lingjuan; Lu, Dan; Qiu, Jifang

    2014-05-01

    A novel 4 × 4 multimode interference couplers based phase-shifted photonic quantization scheme using multiwavelength mode locked pulse lasers as sampling source for all-optical analog-to-digital converter is proposed. Numerical analysis indicates that 8-bit quantization resolution operating at 40 GHz bandwidth could be achieved with an incident average optical power of 1.932 mW to each photodiode. The whole scheme can be integrated on a InP-based chip.

  17. Formation and all-optical control of optical patterns in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Binder, R.; Tsang, C. Y.; Tse, Y. C.; Luk, M. H.; Kwong, N. H.; Chan, Chris K. P.; Leung, P. T.; Lewandowski, P.; Schumacher, Stefan; Lafont, O.; Baudin, E.; Tignon, J.

    2016-05-01

    Semiconductor microcavities offer a unique way to combine transient all-optical manipulation of GaAs quantum wells with the benefits of structural advantages of microcavities. In these systems, exciton-polaritons have dispersion relations with very small effective masses. This has enabled prominent effects, for example polaritonic Bose condensation, but it can also be exploited for the design of all-optical communication devices. The latter involves non-equilibrium phase transitions in the spatial arrangement of exciton-polaritons. We consider the case of optical pumping with normal incidence, yielding a spatially homogeneous distribution of exciton-polaritons in optical cavities containing the quantum wells. Exciton-exciton interactions can trigger instabilities if certain threshold behavior requirements are met. Such instabilities can lead, for example, to the spontaneous formation of hexagonal polariton lattices (corresponding to six-spot patterns in the far field), or to rolls (corresponding to two-spot far field patterns). The competition among these patterns can be controlled to a certain degree by applying control beams. In this paper, we summarize the theory of pattern formation and election in microcavities and illustrate the switching between patterns via simulation results.

  18. Ultrafast, low-power, all-optical switching via birefringent phase-matched transverse mode conversion in integrated waveguides.

    PubMed

    Hellwig, Tim; Epping, Jörn P; Schnack, Martin; Boller, Klaus-J; Fallnich, Carsten

    2015-07-27

    We demonstrate the potential of birefringence-based, all-optical, ultrafast conversion between the transverse modes in integrated optical waveguides by modelling the conversion process by numerically solving the multi-mode coupled nonlinear Schroedinger equations. The observed conversion is induced by a control beam and due to the Kerr effect, resulting in a transient index grating which coherently scatters probe light from one transverse waveguide mode into another. We introduce birefringent phase matching to enable efficient all-optically induced mode conversion at different wavelengths of the control and probe beam. It is shown that tailoring the waveguide geometry can be exploited to explicitly minimize intermodal group delay as well as to maximize the nonlinear coefficient, under the constraint of a phase matching condition. The waveguide geometries investigated here, allow for mode conversion with over two orders of magnitude reduced control pulse energy compared to previous schemes and thereby promise nonlinear mode switching exceeding efficiencies of 90% at switching energies below 1 nJ. PMID:26367581

  19. Polarization Maintaining Fibre Loop Mirror for NRZ-to-PRZ Conversion in All-Optical Clock Recovery

    NASA Astrophysics Data System (ADS)

    Xu, Fan; Zhang, Xin-Liang; Liu, Hai-Rong; Liu, De-Ming; Huang, De-Xiu

    2006-02-01

    We propose a novel configuration for clock extraction by converting the NRZ data into the PRZ data and by employing a polarization-maintaining fibre loop mirror (PMFLM) which is usually used as an optical comb filter. It is found that the PMFLM can simply be constructed by a polarization controller and polarization-maintaining fibre (PMF). We theoretically analyse the principle of PMFLM for the NRZ-to-PRZ conversion. Experimentally we demonstrate 10 Gbit/s all-optical clock recovery through our proposed setup. It is shown that recovered clock signal with an extinction ratio above 10 dB can be achieved.

  20. All-optical mode conversion via spatially multimode four-wave mixing

    NASA Astrophysics Data System (ADS)

    Danaci, Onur; Rios, Christian; Glasser, Ryan T.

    2016-07-01

    We experimentally demonstrate the conversion of a Gaussian beam to an approximate Bessel–Gauss mode by making use of a non-collinear four-wave mixing (4WM) process in hot atomic vapor. The presence of a strong, spatially non-Gaussian pump both converts the probe beam into a non-Gaussian mode, and generates a conjugate beam that is in a similar non-Gaussian mode. The resulting probe and conjugate modes are compared to the output of a Gaussian beam incident on an annular aperture that is then spatially filtered according to the phase-matching conditions imposed by the 4WM process. We find that the resulting experimental data agrees well with both numerical simulations, as well as analytical formulae describing the effects of annular apertures on Gaussian modes. These results show that spatially multimode gain platforms may be used as a new method of mode conversion.

  1. All-optical logic gates and wavelength conversion via the injection locking of a Fabry-Perot semiconductor laser

    NASA Astrophysics Data System (ADS)

    Harvey, E.; Pochet, M.; Schmidt, J.; Locke, T.; Naderi, N.; Usechak, N. G.

    2013-03-01

    This work investigates the implementation of all-optical logic gates based on optical injection locking (OIL). All-optical inverting, NOR, and NAND gates are experimentally demonstrated using two distributed feedback (DFB) lasers, a multi-mode Fabry-Perot laser diode, and an optical band-pass filter. The DFB lasers are externally modulated to represent logic inputs into the cavity of the multi-mode Fabry-Perot slave laser. The input DFB (master) lasers' wavelengths are aligned with the longitudinal modes of the Fabry-Perot slave laser and their optical power is used to modulate the injection conditions in the Fabry-Perot slave laser. The optical band-pass filter is used to select a Fabry- Perot mode that is either suppressed or transmitted given the logic state of the injecting master laser signals. When the input signal(s) is (are) in the on state, injection locking, and thus the suppression of the non-injected Fabry-Perot modes, is induced, yielding a dynamic system that can be used to implement photonic logic functions. Additionally, all-optical photonic processing is achieved using the cavity-mode shift produced in the injected slave laser under external optical injection. The inverting logic case can also be used as a wavelength converter — a key component in advanced wavelength-division multiplexing networks. As a result of this experimental investigation, a more comprehensive understanding of the locking parameters involved in injecting multiple lasers into a multi-mode cavity and the logic transition time is achieved. The performance of optical logic computations and wavelength conversion has the potential for ultrafast operation, limited primarily by the photon decay rate in the slave laser.

  2. Polarization insensitive all-optical up-conversion for ROF systems based on parallel pump FWM in a SOA.

    PubMed

    Lu, Jia; Dong, Ze; Cao, Zizheng; Chen, Lin; Wen, Shuangchun; Yu, Jianguo

    2009-04-27

    We have proposed and experimentally investigated polarization insensitive all-optical up-conversion for ROF system based on FWM in a semiconductor optical amplifier (SOA). The parallel pump is generated based on odd-order optical sidebands and carrier suppression using an external intensity modulator and a cascaded optical filter. Therefore, the two pumps are always parallel and phase locked, which makes system polarization insensitive. After FWM in a SOA and optical filtering, similar to single sideband (SSB) 40 GHz optical millimeter-wave is generated only using 10 GHz RF as local oscillator (LO). The receiver sensitivity at a BER of 10(-9) for the up-converted signals is -28.4 dBm. The power penalty for the up-converted downstream signals is smaller than 1 dBm after 20 km SSMF-28 transmission. PMID:19399069

  3. Local oscillator free all optical OOK signal frequency up conversion enabled by injection locking of Fabry-Pérot laser

    NASA Astrophysics Data System (ADS)

    Han, Bing-chen; Yu, Jin-long; Wang, Wen-rui; Wang, Ju; Shi, Yun-long

    2014-08-01

    We demonstrate an all optical up-conversion system by injecting low bitrates baseband OOK signal directly into a conventional Fabry-Pérot laser diode (FP-LD). Radio frequency (RF) carrier is generated due to period-one (P1) oscillation state of nonlinear dynamics system (NDS) in the FP-LD with the injection of external optical signal. No extra high speed and expensive local oscillator is required for the up-conversion. Based on this approach, we experimentally achieved the up-conversion of 2 Gbps RZ-OOK baseband signal to 12 GHz and 14.28 GHz RF carriers, and 2.5 Gbps NRZ-OOK baseband signal to 10 GHz, 18.2 GHz and 20.88 GHz RF carriers respectively. The obtained 20.88 GHz RF carriers have a signal to side mode suppression ratio of 29 dB, and phase noise of -84.2 dBc/Hz@10 kHz.

  4. All-optical quantization and coding scheme for ultrafast analog-to-digital conversion exploiting polarization switches based on nonlinear polarization rotation in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Wen, Huashun; Wang, Hongxiang; Ji, Yuefeng

    2012-08-01

    A novel all-optical quantization and coding scheme for ultrafast analog-to-digital (A/D) conversion exploiting polarization switches (PSWs) based on nonlinear polarization rotation (NPR) in semiconductor optical amplifiers (SOAs) is proposed. In addition, a theoretical model for the polarization switch based on NPR is presented. Through cascading two PSWs, a 2-period transfer function for 3-bit long all-optical quantization and coding is realized numerically for the first time to the authors' knowledge. The effective number of bits (ENOB), the limitation of bandwidth and conversion speed and the scalability are also investigated. The proposed all-optical quantization and coding scheme, combined with existing all-optical sampling techniques, will enable ultrafast A/D conversion at operating speed of hundreds of Gs/s with at least 3 bit resolution, and allows low optical power requirements, photonic integration, and easy scalability.

  5. A novel ultrafast all-optical NRZ to RZ format converter based on Sagnac interferometric structure

    NASA Astrophysics Data System (ADS)

    Chen, Zhixin

    2008-11-01

    A simple novel ultrafast scheme of all-optical nonreturn-to-zero(NRZ) to return-to-zero(RZ) is proposed based on Sagnac interferometric structure. The operations of this scheme at 40Gbit/s 27-1 PRBS sequences are simulated correctly with the output extinction ratio more than 19.1dB. Through built theoretical model and numerical analysis, the operating characteristics of the scheme are illustrated. Furthermore, the carrier recovery time of the SOA is no more a crucial parameter to restrict the operation speed of this scheme.

  6. All-optical formation of coherent dark states of silicon-vacancy spins in diamond.

    PubMed

    Pingault, Benjamin; Becker, Jonas N; Schulte, Carsten H H; Arend, Carsten; Hepp, Christian; Godde, Tillmann; Tartakovskii, Alexander I; Markham, Matthew; Becher, Christoph; Atatüre, Mete

    2014-12-31

    Spin impurities in diamond can be versatile tools for a wide range of solid-state-based quantum technologies, but finding spin impurities that offer sufficient quality in both photonic and spin properties remains a challenge for this pursuit. The silicon-vacancy center has recently attracted much interest because of its spin-accessible optical transitions and the quality of its optical spectrum. Complementing these properties, spin coherence is essential for the suitability of this center as a spin-photon quantum interface. Here, we report all-optical generation of coherent superpositions of spin states in the ground state of a negatively charged silicon-vacancy center using coherent population trapping. Our measurements reveal a characteristic spin coherence time, T2*, exceeding 45 nanoseconds at 4 K. We further investigate the role of phonon-mediated coupling between orbital states as a source of irreversible decoherence. Our results indicate the feasibility of all-optical coherent control of silicon-vacancy spins using ultrafast laser pulses. PMID:25615329

  7. A metro-access integrated network with all-optical virtual private network function using DPSK/ASK modulation format

    NASA Astrophysics Data System (ADS)

    Tian, Yue; Leng, Lufeng; Su, Yikai

    2008-11-01

    All-optical virtual private network (VPN), which offers dedicated optical channels to connect users within a VPN group, is considered a promising approach to efficient internetworking with low latency and enhanced security implemented in the physical layer. On the other hand, time-division multiplexed (TDM) / wavelength-division multiplexed (WDM) network architecture based on a feeder-ring with access-tree topology, is considered a pragmatic migration scenario from current TDM-PONs to future WDM-PONs and a potential convergence scheme for access and metropolitan networks, due to its efficiently shared hardware and bandwidth resources. All-optical VPN internetworking in such a metro-access integrated structure is expected to cover a wider service area and therefore is highly desirable. In this paper, we present a TDM/WDM metro-access integrated network supporting all-optical VPN internetworking among ONUs in different sub- PONs based on orthogonal differential-phase-shift keying (DPSK) / amplitude-shift keying (ASK) modulation format. In each ONU, no laser but a single Mach-Zehnder modulator (MZM) is needed for the upstream and VPN signal generation, which is cost-effective. Experiments and simulations are performed to verify its feasibility as a potential solution to the future access service.

  8. A novel approach to all-optical wavelength conversion by utilizing a reflective semiconductor optical amplifier in a co-propagation scheme

    NASA Astrophysics Data System (ADS)

    Guo, L. Q.; Connelly, M. J.

    2008-09-01

    Nonlinear optical gain modulation in an InGaAsP/InP bulk reflective semiconductor optical amplifier (RSOA) is studied. The differences of the optical properties between RSOAs and conventional SOAs are initially investigated. All-optical wavelength conversion based on nonlinear gain modulation in RSOAs is demonstrated at a bit rate of 2.488 Gbit/s. It is shown that a bit-error-rate of <10-9 can be achieved and an extinction ratio of >9 dB can be obtained at a bit rate of 2.488 Gbit/s with a 231-1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). In comparison with conventional SOAs, wavelength conversion by RSOAs shows much improved performances in high-speed all-optical wavelength conversions.

  9. Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion

    PubMed Central

    Morichetti, Francesco; Canciamilla, Antonio; Ferrari, Carlo; Samarelli, Antonio; Sorel, Marc; Melloni, Andrea

    2011-01-01

    Wave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s−1 PMID:21540838

  10. Investigation of data-format-transparent multiwavelength all-optical clock recovery using a single FP-SOA

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Zhang, Xinliang; Xu, Enming

    2011-10-01

    Multiwavelength clock recovery (CR) is desired to perform all-optical parallel processing, which has potential application in optical communication systems that use WDM technology. Fabry-Pérot semiconductor optical amplifier (FP-SOA) can perform the similar filter function as passive FP filter, and can simultaneously provide gain for oscillation pulses in the cavity; it is essentially an active filter. We experimentally demonstrated simultaneous multiwavelength all-optical CR from input 36.47-Gb/s pseudo-return-zero (PRZ) data and non-return-zero (NRZ) data using a single multi-quantum-well (MQW) FP-SOA with facets reflectivity of 30%. The presented multiwavelength CR scheme is also suitable for PSK signals. Dual-channel CR from input two channels 36.47-Gb/s 2 23-1 NRZ-DPSK data located at different wavelength is experimentally demonstrated. This scheme is transparent for data formats, which is very important for next generation optical networks.

  11. PPLN-based all-optical 40 Gbit/s ODB/AMI/FSK wavelength conversion and FSK logic NOT gate

    NASA Astrophysics Data System (ADS)

    Wang, J.; Sun, Q.; Sun, J.; Hu, Z.

    2009-07-01

    We propose and demonstrate all-optical wavelength conversion for optical duobinary (ODB), alternate-mark inversion (AMI), and frequency-shift keying (FSK) signals and a logic NOT gate for a FSK signal based on cascaded second-harmonic generation and difference-frequency generation (cSHG/DFG) in a periodically poled lithium niobate (PPLN) waveguide. ODB/AMI/FSK are generated from the demodulation of differential phase-shift keying (DPSK) using one-bit-delay fiber delay interferometer (FDI). PPLN-based 40 Gbit/s ODB/AMI/FSK wavelength conversion and FSK logic NOT gate are simultaneously implemented in the experiment.

  12. On the impact of fiber-delay-lines (FDL) in an all-optical network (AON) bottleneck without wavelength conversion

    NASA Astrophysics Data System (ADS)

    Argibay-Losada, Pablo Jesus; Sahin, Gokhan

    2014-08-01

    Random access memories (RAM) are fundamental in conventional electronic switches and routers to manage short-term congestion and to decrease data loss probabilities. Switches in all-optical networks (AONs), however, do not have access to optical RAM, and therefore are prone to much higher loss levels than their electronic counterparts. Fiber-delay-lines (FDLs), able to delay an optical data packet a fixed amount of time, have been proposed in the literature as a means to alleviate those high loss levels. However, they are extremely bulky to manage, so their usage introduces a trade-off between practicality and performance in the design and operation of the AON. In this paper we study the influence that FDLs have in the performance of flows crossing an all-optical switch that acts as their bottleneck. We show how extremely low numbers of FDLs (e.g., 1 or 2) can help in reducing losses by several orders of magnitude in several illustrative scenarios with high aggregation levels. Our results therefore suggest that FDLs can be a practical means of dealing with congestion in AONs in the absence of optical RAM buffers or of suitable data interchange protocols specifically designed for AONs.

  13. On-chip all-optical wavelength conversion of multicarrier, multilevel modulation (OFDM m-QAM) signals using a silicon waveguide.

    PubMed

    Li, Chao; Gui, Chengcheng; Xiao, Xi; Yang, Qi; Yu, Shaohua; Wang, Jian

    2014-08-01

    We report on-chip all-optical wavelength conversion of multicarrier multilevel modulation signals in a silicon waveguide. Using orthogonal frequency-division multiplexing (OFDM) combined with advanced multilevel quadrature amplitude modulation (QAM) signals (i.e., OFDM m-QAM), we experimentally demonstrate all-optical wavelength conversions of 3.2 Gbaud/s OFDM 16/32/64/128-QAM signals based on the degenerate four-wave mixing (FWM) nonlinear effect in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼3  dB for OFDM 16-QAM and ∼4  dB for OFDM 32-QAM at 7% forward error correction (FEC) threshold and ∼3.5  dB for OFDM 64-QAM and ∼4.5  dB for OFDM 128-QAM at 20% FEC threshold. The observed clear constellations of converted idlers imply favorable performance obtained for silicon-waveguide-based OFDM 16/32/64/128-QAM wavelength conversions. PMID:25078234

  14. Measurement of SFDR and noise in EDF amplified analog RF links using all-optical down-conversion and balanced receivers

    NASA Astrophysics Data System (ADS)

    Middleton, Charles; Borbath, Michael; Wyatt, Jeff; DeSalvo, Richard

    2008-04-01

    Optical down-conversion techniques have become an increasingly popular architecture to realize Multi-band Enterprise Terminals (MET), Synthetic Aperture Radar (SAR), Optical Arbitrary Waveform Generation (OAWG), RF Channelizers and other technologies that need rapid frequency agile tunability in the microwave and millimeter RF bands. We describe recent SFDR, NF, Gain, and Noise modeling and measurements of Erbium-doped-fiber amplified analog RF optical links implementing all-optical down-conversion and balanced photodiode receivers. We describe measurements made on our newly designed extensive test-bed utilizing a wide array of high powered single and balanced photodiodes, polarization preserving output LN modulators, EAMs, LIMs, tunable lasers, EDFAs, RF Amplifiers, and other components to fully characterize direct and coherent detection techniques. Additionally, we compare these experimental results to our comprehensive MATLAB system modeling and optimization software tools.

  15. All-optical cryptography of M-QAM formats by using two-dimensional spectrally sliced keys.

    PubMed

    Abbade, Marcelo L F; Cvijetic, Milorad; Messani, Carlos A; Alves, Cleiton J; Tenenbaum, Stefan

    2015-05-10

    There has been an increased interest in enhancing the security of optical communications systems and networks. All-optical cryptography methods have been considered as an alternative to electronic data encryption. In this paper we propose and verify the use of a novel all-optical scheme based on cryptographic keys applied on the spectral signal for encryption of the M-QAM modulated data with bit rates of up to 200 gigabits per second. PMID:25967489

  16. The influence of thermal and free carrier dispersion effects on all-optical wavelength conversion in a silicon racetrack-shaped microring resonator

    NASA Astrophysics Data System (ADS)

    Wang, Zhaolu; Liu, Hongjun; Sun, Qibing; Huang, Nan; Li, Shaopeng; Han, Jing

    2016-07-01

    We experimentally demonstrate ultra-low pump power wavelength conversion based on four-wave mixing in a silicon racetrack-shaped microring resonator. When the pump and signal are located at the resonance wavelengths, wavelength conversion with a pump power of only 1 mW can be realized in this microring resonator because of the resonant enhancement of the device. However, saturation of the conversion efficiency occurs because of the shift of the resonance peak, which is caused by the change of the effective refractive index induced by a combination of thermal and free carrier dispersion effects, and it is demonstrated that the thermal effect is the leading-order factor for the change of the refractive index. The maximum conversion efficiency of  ‑21 dB is obtained when the pump power is less than 12 mW. This ultra-low-power on-chip wavelength convertor based on a silicon microring resonator can find important potential applications in highly integrated optical circuits for all-optical signal processing.

  17. Chromatic dispersion induced PM-AM conversion and its application in the all-optical clock recovery of NRZ-DPSK signals

    NASA Astrophysics Data System (ADS)

    Tang, Ming; Fu, Songnian; Zhong, Wen-de; Wen, Yang Jing; Shum, Ping

    2007-11-01

    We investigated the property of conversion between phase modulation (PM) and amplitude modulation (AM) in optical fiber transmission link due to chromatic dispersion (CD) for the purpose of clock information generation. As a result, a novel all-optical clock recovery (CR) scheme from 10 Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signal has been demonstrated experimentally. We introduce a chromatic dispersion induced clock tone from the NRZ-DPSK signal and feed it into a free-running semiconductor optical amplifier (SOA) based fiber ring laser to achieve an injection mode-locking. The generated mode-locked pulse is the corresponding regenerated clock of the original signal. Since no special component is required for NRZ-DPSK demodulation, our proposed method is very promising because of its simple configuration and higher stability. In experiments, 20km standard single mode fiber is employed to accumulate CD and generate PM-AM conversion hence regenerate clock tone of the NRZ-DPSK signal. The recovered clock signal with the extinction ratio over 15 dB and the root-mean-square timing jitter of 720 fs is achieved under 2 31-1 pseudorandom binary sequence NRZ-DPSK signals measurement. We also demonstrated a similar CR system by using a chirped fiber Bragg grating (CFBG) as the dispersion device. With the same operation principle, it is quite convenient and promising to extend our configuration to implement all-optical CR for NRZ-DPSK signal with data rate up to 40Gbps.

  18. All-optical analog comparator.

    PubMed

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical '1' or '0' by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  19. All-optical analog comparator

    PubMed Central

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-01-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical ‘1’ or ‘0’ by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function. PMID:27550874

  20. All-optical switching by Kerr nonlinear prism and its application to of binary-to-gray-to-binary code conversion

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Sarkar, Tamal

    2012-09-01

    Nonlinear optics deals with numerous physical phenomena associated with nonlinear cubic susceptibility. In this paper, we have proposed an all-optical switching principle using Kerr effect considering the passage of optical wave through a prism made of non-linear material like fused silica. The performances of the optical switch as well as its various properties were also done by numerical simulation. Furthermore, we also proposed all-optical binary-to-Gray and Gary-to-binary (radix 2) code convertor circuits by this proposed architecture.

  1. All-optical clock recovery CSRZ-format data at 40Gbit/s using SOA-based ring laser

    NASA Astrophysics Data System (ADS)

    Chen, Zhixin

    2008-11-01

    The paper firstly demonstrates a theoretical investigation of clock recovery from carrier-suppressed return-to-zero (CSRZ) modulation format data at 40Gbit/s by using SOA-based ring laser. And a completely numerical analysis about the clock characteristics at 40Gbit/s is done, which is an effective guide for experiment and necessary to optimize the system performance. Meanwhile, simulation results show high-quality clock recovery from 27-1 PRBS CSRZ data at 40Gbit/s can be achieved by using higher power assist CW light into a SOA-based ring laser.

  2. All-optical NRZ-to-PRZ format transformer with an injection-locked Fabry-Perot laser diode at unlasing condition

    NASA Astrophysics Data System (ADS)

    Chang, Yung-Cheng; Lin, Yu-Huang; Chen, J. H.; Lin, Gong-Ru

    2004-09-01

    By using an optical nonreturn-to-zero (NRZ) format data-stream to injection-lock an synchronously modulated Fabry-Perot laser diode at below threshold condition (without DC driving current), an output data-stream with pseudo-return-to-zero (PRZ) format can be generated at bit rate of up to 2.488 Gbit/s. Such an NRZ-to-PRZ format transformation is due to the injectionlocking induced gain-switching of the FPLD with the incoming NRZ data. The PRZ data-stream with a maximum on/off extinction ratio of 12.2 dB is obtained under the optical injecting power of -2 dBm and the RF driving power of 24.4 dBm. The best side-mode suppression ratio of 40 dB and the lowest timing jitter of 0.4 ps for the PRZ data-stream are observed. A power penalty of 1.2 dB is measured at a bit-error rate of 10-9 after NRZ-to-PRZ transformation. In application, the demonstration of an all-optical OR logic gate using the FPLD-based NRZ-to-PRZ transformer is also reported.

  3. Pattern-effect-free all-optical wavelength conversion using a hydrogenated amorphous silicon waveguide with ultra-fast carrier decay.

    PubMed

    Suda, Satoshi; Tanizawa, Ken; Sakakibara, Youichi; Kamei, Toshihiro; Nakanishi, Kouichi; Itoga, Emiko; Ogasawara, Takeshi; Takei, Ryohei; Kawashima, Hitoshi; Namiki, Shu; Mori, Masahiko; Hasama, Toshifumi; Ishikawa, Hiroshi

    2012-04-15

    Ultra-fast carrier decay, recently discovered in a hydrogenated amorphous silicon waveguide, can be exploited for pattern-effect-free all-optical signal processing based on optical Kerr nonlinearity. In this study, we utilized a 10 Gbit/s RZ-OOK data stream as a pump for degenerate four-wave mixing in a low-loss hydrogenated amorphous silicon waveguide. The propagation loss of the waveguide used was 1.0±0.2 dB/cm at 1550 nm. Unlike crystalline silicon waveguides, no noticeable difference was observed in the BER characteristics between the cases of PRBS 2(7)-1 and 2(31)-1. PMID:22513693

  4. Strip silicon waveguide for code synchronization in all-optical analog-to-digital conversion based on a lumped time-delay compensation scheme

    NASA Astrophysics Data System (ADS)

    Sha, Li; Zhi-Guo, Shi; Zhe, Kang; Chong-Xiu, Yu; Jian-Ping, Wang

    2016-04-01

    An all-optical analog-to-digital converter (ADC) based on the nonlinear effect in a silicon waveguide is a promising candidate for overcoming the limitation of electronic devices and is suitable for photonic integration. In this paper, a lumped time-delay compensation scheme with 2-bit quantization resolution is proposed. A strip silicon waveguide is designed and used to compensate for the entire time-delays of the optical pulses after a soliton self-frequency shift (SSFS) module within a wavelength range of 1550 nm–1580 nm. A dispersion coefficient as high as –19800 ps/(km·nm) with ±0.5 ps/(km·nm) variation is predicted for the strip waveguide. The simulation results show that the maximum supportable sampling rate (MSSR) is 50.45 GSa/s with full width at half maximum (FWHM) variation less than 2.52 ps, along with the 2-bit effective-number-of-bit and Gray code output. Project supported by the Fundamental Research Funds for the Central Universities, China (Grant No. FRF-TP-15-030A1) and China Postdoctoral Science Foundation (Grant No. 2015M580978).

  5. Degenerate four-wave mixing based all-optical wavelength conversion in a semiconductor optical amplifier and highly-nonlinear photonic crystal fiber parametric loop mirror

    NASA Astrophysics Data System (ADS)

    Liu, Jianguo; Cheng, Tee Hiang; Yeo, Yong kee; Wang, Yixin; Xue, Lifang; Wang, Dawei; Yu, Xiaojun

    2008-11-01

    The idler is separated from the co-propagating pump in a degenerate four-wave mixing (DFWM) with a symmetrical parametric loop mirror (PALM), which is composed of two identical SOAs and a 70 m highly-nonlinear photonic crystal fiber (HN-PCF). The signal and pump are coupled into the symmetrical PALM from different ports, respectively. After the DFWM based wavelength conversion (WC) in the clockwise and anticlockwise, the idler exits from the signal port, while the pump outputs from its input port. Therefore, the pump is effectively suppressed in the idler channel without a high-speed tunable filter. Contrast to a traditional PALM, the DFWM based conversion efficiency is increased greatly, and the functions of the amplification and the WC are integrated in the smart SOA and HN-PCF PALM.

  6. Ultrafast all-optical switching and error-free 10 Gbit/s wavelength conversion in hybrid InP-silicon on insulator nanocavities using surface quantum wells

    SciTech Connect

    Bazin, Alexandre; Monnier, Paul; Beaudoin, Grégoire; Sagnes, Isabelle; Raj, Rama; Lenglé, Kevin; Gay, Mathilde; Bramerie, Laurent; Braive, Rémy; Raineri, Fabrice

    2014-01-06

    Ultrafast switching with low energies is demonstrated using InP photonic crystal nanocavities embedding InGaAs surface quantum wells heterogeneously integrated to a silicon on insulator waveguide circuitry. Thanks to the engineered enhancement of surface non radiative recombination of carriers, switching time is obtained to be as fast as 10 ps. These hybrid nanostructures are shown to be capable of achieving systems level performance by demonstrating error free wavelength conversion at 10 Gbit/s with 6 mW switching powers.

  7. Formation of alcohol conversion catalysts

    DOEpatents

    Wachs, Israel E.; Cai, Yeping

    2001-01-01

    The method of the present invention involves a composition containing an intimate mixture of (a) metal oxide support particles and (b) a catalytically active metal oxide from Groups VA, VIA, or VIIA, its method of manufacture, and its method of use for converting alcohols to aldehydes. During the conversion process, catalytically active metal oxide from the discrete catalytic metal oxide particles migrates to the oxide support particles and forms a monolayer of catalytically active metal oxide on the oxide support particle to form a catalyst composition having a higher specific activity than the admixed particle composition.

  8. All optical OFDM transmission systems

    NASA Astrophysics Data System (ADS)

    Rhee, June-Koo K.; Lim, Seong-Jin; Kserawi, Malaz

    2011-12-01

    All-optical OFDM data transmission opens up a new realm of advanced optical transmission at extreme data rates, as subcarriers are multiplexed and demultiplexed by all optical discrete Fourier transforms (DFT). This paper reviews the principles of all optical OFDM transmission and its system application techniques, providing the generic ideas and the practical implementation issues to achieve 100Gbps or higher data rates with a spectral efficiency of 1 bps/Hz or better. This paper also include discussions on all-optical OFDM implementation variants such as an AWG-based OFDM multiplexer and demultiplexer, a receiver design without optical sampling, a transmitter design with frequency-locked cw lasers, an OFDM cyclic prefix designs, and a chromatic dispersion mitigation technique.

  9. Fast all-optical switch

    NASA Technical Reports Server (NTRS)

    Shay, Thomas M. (Inventor); Poliakov, Evgeni Y. (Inventor); Hazzard, David A. (Inventor)

    2001-01-01

    An apparatus and method wherein polarization rotation in alkali vapors or other mediums is used for all-optical switching and digital logic and where the rate of operation is proportional to the amplitude of the pump field. High rates of speed are accomplished by Rabi flopping of the atomic states using a continuously operating monochromatic atomic beam as the pump.

  10. Formate Formation and Formate Conversion in Biological Fuels Production

    PubMed Central

    Crable, Bryan R.; Plugge, Caroline M.; McInerney, Michael J.; Stams, Alfons J. M.

    2011-01-01

    Biomethanation is a mature technology for fuel production. Fourth generation biofuels research will focus on sequestering CO2 and providing carbon-neutral or carbon-negative strategies to cope with dwindling fossil fuel supplies and environmental impact. Formate is an important intermediate in the methanogenic breakdown of complex organic material and serves as an important precursor for biological fuels production in the form of methane, hydrogen, and potentially methanol. Formate is produced by either CoA-dependent cleavage of pyruvate or enzymatic reduction of CO2 in an NADH- or ferredoxin-dependent manner. Formate is consumed through oxidation to CO2 and H2 or can be further reduced via the Wood-Ljungdahl pathway for carbon fixation or industrially for the production of methanol. Here, we review the enzymes involved in the interconversion of formate and discuss potential applications for biofuels production. PMID:21687599

  11. All-optical encrypted movie.

    PubMed

    Mosso, Fabian; Barrera, John Fredy; Tebaldi, Myrian; Bolognini, Néstor; Torroba, Roberto

    2011-03-14

    We introduce for the first time the concept of an all-optical encrypted movie. This movie joints several encrypted frames corresponding to a time evolving situation employing the same encoding mask. Thanks to a multiplexing operation we compact the encrypted movie information into a single package. But the decryption of this single package implies the existence of cross-talk if we do not adequately pre-process the encoded information before multiplexing. In this regard, we introduce a grating modulation to each encoded image, and then we proceed to multiplexing. After appropriate filtering and synchronizing procedures applied to the multiplexing, we are able to decrypt and to reproduce the movie. This movie is only properly decoded when in possession of the right decoding key. The concept development is carried-out in virtual optical systems, both for the encrypting and the filtering-decrypting stages. Experimental results are shown to confirm our approach. PMID:21445211

  12. Fiber Bragg grating based notch filter for bit-rate-transparent NRZ to PRZ format conversion with two-degree-of-freedom optimization

    NASA Astrophysics Data System (ADS)

    Cao, Hui; Shu, Xuewen; Atai, Javid; Zuo, Jun; Xiong, Bangyun; Shen, Fangcheng; Liu, xin; Cheng, Jianqun

    2015-02-01

    We propose a novel notch-filtering scheme for bit-rate transparent all-optical NRZ-to-PRZ format conversion. The scheme is based on a two-degree-of-freedom optimally designed fiber Bragg grating. It is shown that a notch filter optimized for any specific operating bit rate can be used to realize high-Q-factor format conversion over a wide bit rate range without requiring any tuning.

  13. All-optical time-stretch digitizer

    NASA Astrophysics Data System (ADS)

    Fard, A. M.; Buckley, B.; Zlatanovic, S.; Brès, C.-S.; Radic, S.; Jalali, B.

    2012-07-01

    We propose and demonstrate an all-optical time-stretch digitizer for real-time capture of ultrafast optical signals, beyond the bandwidths achievable by electronics. This approach uniquely combines four-wave mixing and photonic time-stretch technique to slow down and record high-speed optical signals. As a proof-of-concept, real-time recording of 40-Gb/s non-return-to-zero on-off-keying optical data stream is experimentally demonstrated using a stretch factor of 54 and 1.5-GHz back-end electronic bandwidth. We also report on the observation of dispersion penalty and its mitigation via single-sideband conversion enabled by an optical bandpass filter. Our technique may provide a path to real-time capture of ultrahigh-speed optical data streams.

  14. High speed all optical networks

    NASA Technical Reports Server (NTRS)

    Chlamtac, Imrich; Ganz, Aura

    1990-01-01

    An inherent problem of conventional point-to-point wide area network (WAN) architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. The first solution to wavelength division multiplexing (WDM) based WAN networks that overcomes this limitation is presented. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs. The principle of the Lightnet architecture is the construction and use of virtual topology networks, embedded in the original network in the wavelength domain. For this construction Lightnets utilize the new concept of lightpaths which constitute the links of the virtual topology. Lightpaths are all-optical, multihop, paths in the network that allow data to be switched through intermediate nodes using high throughput passive optical switches. The use of the virtual topologies and the associated switching design introduce a number of new ideas, which are discussed in detail.

  15. All-optical flip-flop based on coupled SOA-PSW

    NASA Astrophysics Data System (ADS)

    Wang, Lina; Wang, Yongjun; Wu, Chen; Wang, Fu

    2016-07-01

    The semiconductor optical amplifier (SOA) has obvious advantages in all-optical signal processing, because of the simple structure, strong non-linearity, and easy integration. A variety of all-optical signal processing functions, such as all-optical wavelength conversion, all-optical logic gates and all-optical sampling, can be completed by SOA. So the SOA has been widespread concerned in the field of all-optical signal processing. Recently, the polarization rotation effect of SOA is receiving considerable interest, and many researchers have launched numerous research work utilizing this effect. In this paper, a new all-optical flip-flop structure using polarization switch (PSW) based on polarization rotation effect of SOA is presented.

  16. Photonic encryption using all optical logic.

    SciTech Connect

    Blansett, Ethan L.; Schroeppel, Richard Crabtree; Tang, Jason D.; Robertson, Perry J.; Vawter, Gregory Allen; Tarman, Thomas David; Pierson, Lyndon George

    2003-12-01

    With the build-out of large transport networks utilizing optical technologies, more and more capacity is being made available. Innovations in Dense Wave Division Multiplexing (DWDM) and the elimination of optical-electrical-optical conversions have brought on advances in communication speeds as we move into 10 Gigabit Ethernet and above. Of course, there is a need to encrypt data on these optical links as the data traverses public and private network backbones. Unfortunately, as the communications infrastructure becomes increasingly optical, advances in encryption (done electronically) have failed to keep up. This project examines the use of optical logic for implementing encryption in the photonic domain to achieve the requisite encryption rates. In order to realize photonic encryption designs, technology developed for electrical logic circuits must be translated to the photonic regime. This paper examines two classes of all optical logic (SEED, gain competition) and how each discrete logic element can be interconnected and cascaded to form an optical circuit. Because there is no known software that can model these devices at a circuit level, the functionality of the SEED and gain competition devices in an optical circuit were modeled in PSpice. PSpice allows modeling of the macro characteristics of the devices in context of a logic element as opposed to device level computational modeling. By representing light intensity as voltage, 'black box' models are generated that accurately represent the intensity response and logic levels in both technologies. By modeling the behavior at the systems level, one can incorporate systems design tools and a simulation environment to aid in the overall functional design. Each black box model of the SEED or gain competition device takes certain parameters (reflectance, intensity, input response), and models the optical ripple and time delay characteristics. These 'black box' models are interconnected and cascaded in an

  17. All-optical signal processing at 10 GHz using a photonic crystal molecule

    SciTech Connect

    Combrié, Sylvain; Lehoucq, Gaëlle; Junay, Alexandra; De Rossi, Alfredo; Malaguti, Stefania; Bellanca, Gaetano; Trillo, Stefano; Ménager, Loic; Peter Reithmaier, Johann

    2013-11-04

    We report on 10 GHz operation of an all-optical gate based on an Indium Phosphide Photonic Crystal Molecule. Wavelength conversion and all-optical mixing of microwave signals are demonstrated using the 2 mW output of a mode locked diode laser. The spectral separation of the optical pump and signal is crucial in suppressing optical cross-talk.

  18. A reconfigurable all-optical VPN based on XGM effect of SOA in WDM PON

    NASA Astrophysics Data System (ADS)

    Hu, Xiaofeng; Zhang, Liang; Cao, Pan; Wang, Tao; Su, Yikai

    2010-12-01

    We propose and experimentally demonstrate a reconfigurable all-optical VPN scheme enabling intercommunications among different ONUs in a WDM PON. Reconfiguration is realized by dynamically setting wavelength conversion of optical VPN signal using a SOA in the OLT.

  19. Rapidly reconfigurable all-optical universal logic gate

    DOEpatents

    Goddard, Lynford L.; Bond, Tiziana C.; Kallman, Jeffrey S.

    2010-09-07

    A new reconfigurable cascadable all-optical on-chip device is presented. The gate operates by combining the Vernier effect with a novel effect, the gain-index lever, to help shift the dominant lasing mode from a mode where the laser light is output at one facet to a mode where it is output at the other facet. Since the laser remains above threshold, the speed of the gate for logic operations as well as for reprogramming the function of the gate is primarily limited to the small signal optical modulation speed of the laser, which can be on the order of up to about tens of GHz. The gate can be rapidly and repeatedly reprogrammed to perform any of the basic digital logic operations by using an appropriate analog optical or electrical signal at the gate selection port. Other all-optical functionality includes wavelength conversion, signal duplication, threshold switching, analog to digital conversion, digital to analog conversion, signal routing, and environment sensing. Since each gate can perform different operations, the functionality of such a cascaded circuit grows exponentially.

  20. Nonlinear fiber applications for ultrafast all-optical signal processing

    NASA Astrophysics Data System (ADS)

    Kravtsov, Konstantin

    In the present dissertation different aspects of all-optical signal processing, enabled by the use of nonlinear fibers, are studied. In particular, we focus on applications of a novel heavily GeO2-doped (HD) nonlinear fiber, that appears to be superior to many other types of nonlinear fibers because of its high nonlinearity and suitability for the use in nonlinear optical loop mirrors (NOLMs). Different functions, such as all-optical switching, thresholding, and wavelength conversion, are demonstrated with the HD fibers in the NOLM configuration. These basic functions are later used for realization of ultrafast time-domain demultiplexers, clock recovery, detectors of short pulses in stealth communications, and primitive elements for analog computations. Another important technology that benefits from the use of nonlinear fiber-based signal processing is optical code-division multiple access (CDMA). It is shown in both theory and experiment that all-optical thresholding is a unique way of improving existing detection methods for optical CDMA. Also, it is the way of implementation of true asynchronous optical spread-spectrum networks, which allows full realization of optical CDMA potential. Some aspects of quantum signal processing and manipulation of quantum states are also studied in this work. It is shown that propagation and collisions of Thirring solitons lead to a substantial squeezing of quantum states, which may find applications for generation of squeezed light.

  1. Bufferless Ultra-High Speed All-Optical Packet Routing

    NASA Astrophysics Data System (ADS)

    Muttagi, Shrihari; Prince, Shanthi

    2011-10-01

    All-Optical network is still in adolescence to cope up with steep rise in data traffic at the backbone network. Routing of packets in optical network depends on the processing speed of the All-Optical routers, thus there is a need to enhance optical processing to curb the delay in packet forwarding unit. In the proposed scheme, the header processing takes place on fly, therefore processing delay is at its lower limit. The objective is to propose a framework which establishes high data rate transmission with least latency in data routing from source to destination. The Routing table and optical header pulses are converted into Pulse Position (PP) format, thus reducing the complexity and in turn the processing delay. Optical pulse matching is exercised which results in multi-output transmission. This results in ultra-high speed packet forwarding unit. In addition, this proposed scheme includes dispersion compensation unit, which makes the data reliable.

  2. All-Optical Nanomechanical Heat Engine

    NASA Astrophysics Data System (ADS)

    Dechant, Andreas; Kiesel, Nikolai; Lutz, Eric

    2015-05-01

    We propose and theoretically investigate a nanomechanical heat engine. We show how a levitated nanoparticle in an optical trap inside a cavity can be used to realize a Stirling cycle in the underdamped regime. The all-optical approach enables fast and flexible control of all thermodynamical parameters and the efficient optimization of the performance of the engine. We develop a systematic optimization procedure to determine optimal driving protocols. Further, we perform numerical simulations with realistic parameters and evaluate the maximum power and the corresponding efficiency.

  3. All-optical nanomechanical heat engine.

    PubMed

    Dechant, Andreas; Kiesel, Nikolai; Lutz, Eric

    2015-05-01

    We propose and theoretically investigate a nanomechanical heat engine. We show how a levitated nanoparticle in an optical trap inside a cavity can be used to realize a Stirling cycle in the underdamped regime. The all-optical approach enables fast and flexible control of all thermodynamical parameters and the efficient optimization of the performance of the engine. We develop a systematic optimization procedure to determine optimal driving protocols. Further, we perform numerical simulations with realistic parameters and evaluate the maximum power and the corresponding efficiency. PMID:26001001

  4. Simple novel all-optical wavelength converter

    NASA Astrophysics Data System (ADS)

    Chen, Zhixin

    2009-02-01

    Based on Sagnac interferometric structure, a simple novel ultrafast scheme for an all-optical wavelength converter is proposed. The operations of this scheme with a 80-Gbits/s return to zero (RZ) pseudorandom bit sequence (PRBS) are simulated correctly with an output extinction ratio of more than 17.2 dB. Through numerical analysis, by comparison of the performance at 40- and 80-Gbits/s operation, the operating characteristics of the scheme are illustrated. Furthermore, the carrier recovery time of the semiconductor amplifier (SOA) is no longer a crucial parameter to restrict the operation speed of this scheme.

  5. Ultrafast all-optical switching in bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Singh, C. P.; Reddy, K. P. J.

    2001-04-01

    All-optical switching has been demonstrated in bacteriorhodopsin based on excited-state nonlinear absorption. A probe laser beam at 640 nm corresponding to the O-state absorption maximum is switched due to a strong pulsed pump laser beam at 570 nm, that corresponds to the maximum ground state absorption. We have studied the effect of variation in pulse width and in small signal absorption coefficient on the switching characteristics. The switching time decreases as the pulse width of the pump beam decreases and the small signal absorption coefficient increases. The switching contrast depends mainly on the peak pumping intensity.

  6. All-optical symmetric ternary logic gate

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2010-09-01

    Symmetric ternary number (radix=3) has three logical states (1¯, 0, 1). It is very much useful in carry free arithmetical operation. Beside this, the logical operation using this type of number system is also effective in high speed computation and communication in multi-valued logic. In this literature all-optical circuits for three basic symmetrical ternary logical operations (inversion, MIN and MAX) are proposed and described. Numerical simulation verifies the theoretical model. In this present scheme the different ternary logical states are represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch has been used categorically in this manuscript.

  7. All optical binary delta-sigma modulator

    NASA Astrophysics Data System (ADS)

    Sayeh, Mohammad R.; Siahmakoun, Azad

    2005-09-01

    This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.

  8. Cold molecules: Formation, ro-vibrational cooling and electronic conversion

    NASA Astrophysics Data System (ADS)

    Horchani, R.

    2016-05-01

    The possibility of controlling all the motion as well as the internal quantum state of a sample of molecules is a long term goal in the cold molecules field. Although many different techniques have been used to produce ultra-cold molecules, in this paper, we will concentrate on the optical pumping technique successfully used to achieve rotational and vibrational cooling of Cs2 molecules. We will review the different photo-association schemes for molecule formation, the detection schemes through photoionization, the ro-vibrational cooling into a single level and finally the electronic conversion. In addition, we will present a theoretical model for both ro-vibrational cooling and electronic conversion that can be used for the preparation of different experiments.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  10. All-Optical Interrogation of Neural Circuits

    PubMed Central

    2015-01-01

    There have been two recent revolutionary advances in neuroscience: First, genetically encoded activity sensors have brought the goal of optical detection of single action potentials in vivo within reach. Second, optogenetic actuators now allow the activity of neurons to be controlled with millisecond precision. These revolutions have now been combined, together with advanced microscopies, to allow “all-optical” readout and manipulation of activity in neural circuits with single-spike and single-neuron precision. This is a transformational advance that will open new frontiers in neuroscience research. Harnessing the power of light in the all-optical approach requires coexpression of genetically encoded activity sensors and optogenetic probes in the same neurons, as well as the ability to simultaneously target and record the light from the selected neurons. It has recently become possible to combine sensors and optical strategies that are sufficiently sensitive and cross talk free to enable single-action-potential sensitivity and precision for both readout and manipulation in the intact brain. The combination of simultaneous readout and manipulation from the same genetically defined cells will enable a wide range of new experiments as well as inspire new technologies for interacting with the brain. The advances described in this review herald a future where the traditional tools used for generations by physiologists to study and interact with the brain—stimulation and recording electrodes—can largely be replaced by light. We outline potential future developments in this field and discuss how the all-optical strategy can be applied to solve fundamental problems in neuroscience. SIGNIFICANCE STATEMENT This review describes the nexus of dramatic recent developments in optogenetic probes, genetically encoded activity sensors, and novel microscopies, which together allow the activity of neural circuits to be recorded and manipulated entirely using light. The

  11. All-optical phase-preserving multilevel amplitude regeneration.

    PubMed

    Roethlingshoefer, Tobias; Richter, Thomas; Schubert, Colja; Onishchukov, Georgy; Schmauss, Bernhard; Leuchs, Gerd

    2014-11-01

    The possibility of all-optical phase-preserving amplitude regeneration for star-8QAM is demonstrated using a modified nonlinear optical loop mirror. Experiments show a reduction in amplitude noise on both amplitude levels simultaneously, considering two different types of signal distortions: deterministic low-frequency amplitude modulation and broadband amplitude noise. Furthermore, using this amplitude regeneration, the robustness against nonlinear phase noise from fiber nonlinearity in a transmission line is increased. The scheme suppresses the conversion of amplitude noise to nonlinear phase noise. This is shown for simultaneous amplitude regeneration of the two amplitude states as well as for amplitude regeneration of the high-power states only. If the transmission is limited by nonlinear phase noise, single-level operation at the more critical higher-power state will benefit because of the wider plateau region. Numerical simulations confirm the experimental results. PMID:25401858

  12. The GALAXIE all-optical FEL project

    SciTech Connect

    Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; and others

    2012-12-21

    We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-high brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

  13. All-optical beamlet train generation

    SciTech Connect

    Cary, John; Giacone, Rodolfo; Nieter, Chet; Bruhwiler, David; Esarey, Eric; Fubiani, Gwenael; Leemans, Wim

    2003-05-12

    One of the critical issues for the development of Laser Wake Field Acceleration (LWFA), which has the promise of creating table-top, GeV accelerators, is the loading of beamlets into the accelerating buckets. All optical injection schemes, which include LILAC, beat-wave colliding pulse injection, wave breaking injection, and phase-kick injection, provide a technique for doing so. Although a single bunch can have desirable properties such as energy spread of the order of a few percent, femtosecond duration k and low emittance (<1 mm-mrad), recent simulations show that such methods lead to efficiencies of transfer of plasma wave energy to beam energy that are low compared with conventional RF accelerators when only a single pulse is generated. Our latest simulations show that one can improve on this situation through the generation of a beamlet train. This can occur naturally through phase-kick injection at the front of the train and transverse wave breaking for the trailing pulses. The result is an efficiency improvement of the order of the number of beamlets in the train.

  14. Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

    SciTech Connect

    Isaacs,H.; Sasaki, K.; Jeffcoate, C.; Laget, V.; Buchheit, R.

    2005-01-01

    We used in situ X-ray adsorption near-edge structure (XANES) to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys (AA 1100, AA2024, and AA7075), and a series of binary A1-Cu alloys. The method employed a new electrochemical cell that can determine the ratio of hexavalent chromium (Cr(VI)) to total chromium (Cr(total)) speciation in conversion coatings as a fraction of exposure time to a chromate solution. The spectra showed that the initial Cr(VI)/Cr(total) ratios are greater than later ones for pure Al and AAl 100, but not for AA2024 and AA7075. Measurements with Al-Cu alloys demonstrated that the difference observed in AA2024 and AA7075 may not be due to Cu alloying. The proportion of Cr(VI) in the coatings becomes approximately constant after 180 s of exposure for all the specimens examined even though the coatings continue to grow.

  15. Nanofiber-based all-optical switches

    NASA Astrophysics Data System (ADS)

    Le Kien, Fam; Rauschenbeutel, A.

    2016-01-01

    We study all-optical switches operating on a single four-level atom with the N -type transition configuration in a two-mode nanofiber cavity with a significant length (on the order of 20 mm) and a moderate finesse (on the order of 300) under the electromagnetically induced transparency (EIT) conditions. In our model, the gate and probe fields are the quantum nanofiber-cavity fields excited by weak classical light pulses, and the parameters of the D2 line of atomic cesium are used. We examine two different switching schemes. The first scheme is based on the effect of the presence of a photon in the gate mode on the EIT of the probe mode. The second scheme is based on the use of EIT to store a photon of the gate mode in the population of an appropriate atomic level, which leads to the reduction of the transmission of the field in the probe mode. We investigate the dependencies of the switching contrast on various parameters, such as the cavity length, the mirror reflectivity, and the detunings and powers of the cavity driving field pulses. For a nanofiber cavity with fiber radius of 250 nm, cavity length of 20 mm, and cavity finesse of 313 and a cesium atom at a distance of 200 nm from the fiber surface, we numerically obtain a switching contrast on the order of about 67% for the first scheme and of about 95% for the second scheme. These switching operations require small mean numbers of photons in the nanofiber cavity gate and probe modes.

  16. All optical modulator based on silicon resonator

    NASA Astrophysics Data System (ADS)

    Pinhas, Hadar; Bidani, Liron; Baharav, Oded; Sinvani, Moshe; Danino, Meir; Zalevsky, Zeev

    2015-08-01

    In this paper we present an all-optical silicon modulator, where a silicon slab (450 μm) thick is coated on both sides to get a Fabry-Perot resonator for laser beam at wavelength of 1550nm. Most of the modulators discussed in literature, are driven by electrical field rather than by light. We investigate new approaches regarding the dependence of the absorption of the optical signal on the control laser pulse at 532 nm having 5nm pulse width. Our silicon based Fabry-Perot resonator increases the intrinsic c-Si finesse to >10, instead of the uncoated silicon with natural finesse of 2.5. The improved finesse is shown to have significant effect on the modulation depth using a pulsed laser. A modulation of 12dB was attained. The modulation is ascribed to two different effects - The Plasma Dispersion Effect (PDE) and the Thermo- Optic Effect (TOE). The PDE causes increase in the signal absorption in silicon via the absorption of the control laser light. On top of that, the transmission of the signal can decrease dramatically in high finesse resonators due to change in the refractive index due to TOE. The changes in the signal's absorption coefficient and in the refractive index are the result of incremental change in the concentration of free carriers. The TOE gives rise to higher refractive index as opposed to the PDE which triggers a decrease in the refractive index. Finally, tradeoff considerations are presented on how to modify one effect to counter the other one, leading to an optimal device having reduced temperature dependence.

  17. All-optical switching and all-optical logic gates based on bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Huang, Yuhua; Wu, Shin-Tson; Zhao, Youyuan

    2004-06-01

    We demonstrate an all-optical switching using a bacteriorhodopsin (bR) film. The transmission of the bR film is investigated using the pump-probe method. A diode-pumped second harmonic YAG laser (λ = 532nm which is around the maximum initial B state absorption) was used as a pumping beam and a cw He-Ne laser (λ = 632 nm which is around the peaks of K and O states) was used as a probe. Due to the nonlinear intensity induced excited state absorption of the K, L, M, N, and O states in the bR photocycle, the switching characteristics are sensitive to the intensity of the probe and pump beams. Based on this property, we design an all-optical operating device functioning as 11 kinds of variable binary all-optical logic gates. The incident 532nm beam acts as an input to the logic gate and the transmission of the 632nm bears the output of the gate.

  18. Fault tolerant all-optical router with photorefractive all-optical switch

    NASA Astrophysics Data System (ADS)

    Kaino, Toshiya; Okamoto, Atsushi; Honma, Satoshi

    2003-08-01

    We propose a new type of the fault tolerant all-optical router (FTAR) by using an all-optical switch with photorefractive two-wave mixing. FTAR can detect a cutoff of a main transmitting line and automatically reroute a signal beam from the main line to a backup line. These functions can increase communication reliability of optical wireless. FTAR is composed of ony all-optical devices without any electronic devices or any mechanical operations. In the new type of FTAR, the routing of the signal beam is controlled by a control beam transmitting on the main line from a different light source at a receiver in the opposite direction with the signal beam. Compared with the previous type of FTAR composed of two photorefractinve crystals, the new configuration offers the simplification of the construction and high transmission efficiency of the signal beam. In this report, we experiment on the FTAR by usign a BaTiO3 and Ar+ laser whose wavelength is 514.5nm, and confirm the fundamental fucntin of FTAR. We give comparison of the result with the numerical analysis. We also analyze the dependence of the switching time on the input beam intensity of the crystal by a numerical analysis and an experiment.

  19. All-optical microwave signal processing based on optical phase modulation

    NASA Astrophysics Data System (ADS)

    Zeng, Fei

    This thesis presents a theoretical and experimental study of optical phase modulation and its applications in all-optical microwave signal processing, which include all-optical microwave filtering, all-optical microwave mixing, optical code-division multiple-access (CDMA) coding, and ultrawideband (UWB) signal generation. All-optical microwave signal processing can be considered as the use of opto-electronic devices and systems to process microwave signals in the optical domain, which provides several significant advantages such as low loss, low dispersion, light weight, high time bandwidth products, and immunity to electromagnetic interference. In conventional approaches, the intensity of an optical carrier is modulated by a microwave signal based on direct modulation or external modulation. The intensity-modulated optical signal is then fed to a photonic circuit or system to achieve specific signal processing functionalities. The microwave signal being processed is usually obtained based on direct detection, i.e., an opto-electronic conversion by use of a photodiode. In this thesis, the research efforts are focused on the optical phase modulation and its applications in all-optical microwave signal processing. To avoid using coherent detection which is complicated and costly, simple and effective phase modulation to intensity modulation (PM-IM) conversion schemes are pursued. Based on a theoretical study of optical phase modulation, two approaches to achieving PM-IM conversions are proposed. In the first approach, the use of chromatic dispersion induced by a dispersive device to alter the phase relationships among the sidebands and the optical carrier of a phase-modulated optical signal to realize PM-IM conversion is investigated. In the second approach, instead of using a dispersive device, the PM-IM conversion is realized based on optical frequency discrimination implemented using an optical filter. We show that the proposed PM-IM conversion schemes can be

  20. All-optical event horizon in an optical analog of a Laval nozzle

    NASA Astrophysics Data System (ADS)

    Elazar, M.; Fleurov, V.; Bar-Ad, S.

    2012-12-01

    Exploiting the fact that light propagation in defocusing nonlinear media can mimic the transonic flow of an equivalent fluid, we demonstrate experimentally the formation of an all-optical event horizon in a waveguide structure akin to a hydrodynamic Laval nozzle. The analog event horizon which forms at the nozzle throat is suggested as a platform for analogous gravity experiments.

  1. All-optical signal processing using dynamic Brillouin gratings

    NASA Astrophysics Data System (ADS)

    Santagiustina, Marco; Chin, Sanghoon; Primerov, Nicolay; Ursini, Leonora; Thévenaz, Luc

    2013-04-01

    The manipulation of dynamic Brillouin gratings in optical fibers is demonstrated to be an extremely flexible technique to achieve, with a single experimental setup, several all-optical signal processing functions. In particular, all-optical time differentiation, time integration and true time reversal are theoretically predicted, and then numerically and experimentally demonstrated. The technique can be exploited to process both photonic and ultra-wide band microwave signals, so enabling many applications in photonics and in radio science.

  2. All-optical signal processing using dynamic Brillouin gratings

    PubMed Central

    Santagiustina, Marco; Chin, Sanghoon; Primerov, Nicolay; Ursini, Leonora; Thévenaz, Luc

    2013-01-01

    The manipulation of dynamic Brillouin gratings in optical fibers is demonstrated to be an extremely flexible technique to achieve, with a single experimental setup, several all-optical signal processing functions. In particular, all-optical time differentiation, time integration and true time reversal are theoretically predicted, and then numerically and experimentally demonstrated. The technique can be exploited to process both photonic and ultra-wide band microwave signals, so enabling many applications in photonics and in radio science. PMID:23549159

  3. Two types of all-optical magnetization switching mechanisms using femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    El Hadri, M. S.; Pirro, P.; Lambert, C.-H.; Petit-Watelot, S.; Quessab, Y.; Hehn, M.; Montaigne, F.; Malinowski, G.; Mangin, S.

    2016-08-01

    Using a time-dependent electrical investigation of the all-optical switching in ferrimagnetic and ferromagnetic Hall crosses via the anomalous Hall effect, intriguing insights into the rich physics underlying the all-optical switching are provided. We demonstrate that two different all-optical magnetization switching mechanisms can be distinguished; a "single pulse" switching for ferrimagnetic GdFeCo alloys, and a "two regimes" switching process for both ferrimagnetic TbCo alloys and ferromagnetic Pt/Co multilayers. We show that the latter takes place at two different time scales, and consists of a steplike helicity-independent multiple-domain formation within the first 1 ms followed by a helicity-dependent remagnetization on several tens of milliseconds.

  4. An approach toward the holy grail in all-optical circuit switching: the monster all-optical crossconnect

    NASA Astrophysics Data System (ADS)

    Riza, Nabeel A.; Mughal, M. J.

    2003-12-01

    A new robust approach is presented for achieving very large fiber port count all-optical crossconnect switches. This three dimensional optics-based switch has built-in alignment capabilities with fault-tolerance, allowing graceful port count scaling.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  6. Photonic encryption : modeling and functional analysis of all optical logic.

    SciTech Connect

    Tang, Jason D.; Schroeppel, Richard Crabtree; Robertson, Perry J.

    2004-10-01

    With the build-out of large transport networks utilizing optical technologies, more and more capacity is being made available. Innovations in Dense Wave Division Multiplexing (DWDM) and the elimination of optical-electrical-optical conversions have brought on advances in communication speeds as we move into 10 Gigabit Ethernet and above. Of course, there is a need to encrypt data on these optical links as the data traverses public and private network backbones. Unfortunately, as the communications infrastructure becomes increasingly optical, advances in encryption (done electronically) have failed to keep up. This project examines the use of optical logic for implementing encryption in the photonic domain to achieve the requisite encryption rates. This paper documents the innovations and advances of work first detailed in 'Photonic Encryption using All Optical Logic,' [1]. A discussion of underlying concepts can be found in SAND2003-4474. In order to realize photonic encryption designs, technology developed for electrical logic circuits must be translated to the photonic regime. This paper examines S-SEED devices and how discrete logic elements can be interconnected and cascaded to form an optical circuit. Because there is no known software that can model these devices at a circuit level, the functionality of S-SEED devices in an optical circuit was modeled in PSpice. PSpice allows modeling of the macro characteristics of the devices in context of a logic element as opposed to device level computational modeling. By representing light intensity as voltage, 'black box' models are generated that accurately represent the intensity response and logic levels in both technologies. By modeling the behavior at the systems level, one can incorporate systems design tools and a simulation environment to aid in the overall functional design. Each black box model takes certain parameters (reflectance, intensity, input response), and models the optical ripple and time delay

  7. An XML based middleware for ECG format conversion.

    PubMed

    Li, Xuchen; Vojisavljevic, Vuk; Fang, Qiang

    2009-01-01

    With the rapid development of information and communication technologies, various e-health solutions have been proposed. The digitized medical images as well as the mono-dimension medical signals are two major forms of medical information that are stored and manipulated within an electronic medical environment. Though a variety of industrial and international standards such as DICOM and HL7 have been proposed, many proprietary formats are still pervasively used by many Hospital Information System (HIS) and Picture Archiving and Communication System (PACS) vendors. Those proprietary formats are the big hurdle to form a nationwide or even worldwide e-health network. Thus there is an imperative need to solve the medical data integration problem. Moreover, many small clinics, many hospitals in developing countries and some regional hospitals in developed countries, which have limited budget, have been shunned from embracing the latest medical information technologies due to their high costs. In this paper, we propose an XML based middleware which acts as a translation engine to seamlessly integrate clinical ECG data from a variety of proprietary data formats. Furthermore, this ECG translation engine is designed in a way that it can be integrated into an existing PACS to provide a low cost medical information integration and storage solution. PMID:19964551

  8. Transmission performance of a wavelength and NRZ-to-RZ format conversion with pulsewidth tunability by combination of SOA- and fiber-based switches.

    PubMed

    Tan, Hung Nguyen; Matsuura, Motoharu; Kishi, Naoto

    2008-11-10

    An all-optical signal processing scheme coupling wavelength conversion and NRZ-to-RZ data format conversion with pulsewidth tunability into one by combination of SOA- and fiber-based switches, is experimentally demonstrated, and its transmission performance is investigated. An 1558 nm NRZ data signal is converted to RZ data format at 1546 nm with widely tunable pulsewidth from 20 % to 80 % duty cycle at the bit-rate of 10 Gb/s. The investigation on transmission performance of the converted RZ signals at each different pulsewidth is carried out over various standard single-mode fiber (SSMF) links up to 65 km long without dispersion compensation. The results clarify a significant improvement on transmission performance of converted signal in comparison with the conventional NRZ signal through tunable pulsewidth management and show the existence of an optimal pulsewidth for the RZ data format at each transmission distance with particular cumulative dispersion. The optimal pulsewidths of the converted RZ signal and its corresponding power penalties against the NRZ signal are also investigated in different SSMF links. PMID:19581998

  9. Simple novel all-optical half-adder

    NASA Astrophysics Data System (ADS)

    Chen, Zhixin

    2010-04-01

    On the basis of Sagnac interferometric structure, a simple novel ultrafast scheme of all-optical half-adder is proposed. The structure comprises two of the same balanced terahertz optical asymmetric demultiplexers (TOADs). One TOAD is utilized to achieve an all-optical XOR gate, which is logic SUM. The other is utilized to obtain an all-optical AND gate, which is logic CARRY. Logical SUM and CARRY are simultaneously realized at 80 Gbit/s. Through numerical analysis, the operating characteristics of the scheme are illustrated at 80 Gbit/s. Furthermore, the carrier recovery time of the semiconductor optical amplifier is no longer a crucial parameter to restrict the operation speed of this scheme.

  10. All-optical pseudorandom bit sequences generator based on TOADs

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2016-03-01

    A scheme for all-optical pseudorandom bit sequences (PRBS) generator is demonstrated with optical logic gate 'XNOR' and all-optical wavelength converter based on cascaded Tera-Hertz Optical Asymmetric Demultiplexer (TOADs). Its feasibility is verified by generation of return-to-zero on-off keying (RZ-OOK) 263-1 PRBS at the speed of 1 Gb/s with 10% duty radio. The high randomness of ultra-long cycle PRBS is validated by successfully passing the standard benchmark test.

  11. Photonic temporal integrator for all-optical computing.

    PubMed

    Slavík, Radan; Park, Yongwoo; Ayotte, Nicolas; Doucet, Serge; Ahn, Tae-Jung; LaRochelle, Sophie; Azaña, José

    2008-10-27

    We report the first experimental realization of an all-optical temporal integrator. The integrator is implemented using an all-fiber active (gain-assisted) filter based on superimposed fiber Bragg gratings made in an Er-Yb co-doped optical fiber that behaves like an 'optical capacitor'. Functionality of this device was tested by integrating different optical pulses, with time duration down to 60 ps, and by integration of two consecutive pulses that had different relative phases, separated by up to 1 ns. The potential of the developed device for implementing all-optical computing systems for solving ordinary differential equations was also experimentally tested. PMID:18958098

  12. All-optical binary phase-coded UWB signal generation for multi-user UWB communications.

    PubMed

    Dong, Jianji; Yu, Yuan; Zhang, Yin; Li, Xiang; Huang, Dexiu; Zhang, Xinliang

    2011-05-23

    An all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) signals is proposed and experimentally demonstrated. The binary phase coding is performed based on all-optical phase modulation in a semiconductor optical amplifier (SOA) and phase modulation to intensity modulation (PM-IM) conversion in a fiber delay interferometer (DI) that serves as a multichannel frequency discriminator. By locating the phase-modulated light waves at the positive and negative slopes of the DI transmission spectra, binary phase encoded UWB codes (0 and π) are generated. We also experimentally demonstrate a bipolar UWB coding system with a code length of 4, operating at 1.25 Gb/s. And the decoding is analyzed as well. Our proposed system has potential application in future high-speed UWB impulse radio over optical fiber access networks. PMID:21643312

  13. All-optical repetition rate multiplication of pseudorandom bit sequences based on cascaded TOADs

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2016-03-01

    A scheme for all-optical repetition rate multiplication of pseudorandom bit sequences (PRBS) is demonstrated with all-optical wavelength conversion and optical logic gate 'OR' based on cascaded Tera-Hertz Optical Asymmetric Demultiplexers (TOADs). Its feasibility is verified by multiplication experiments from 500 Mb/s to 4 Gb/s for 23-1 PRBS and from 1 Gb/s to 4 Gb/s for 27-1 PRBS. This scheme can be employed for rate multiplication for much longer cycle PRBS at much higher bit rate over 40 Gb/s when the time-delay, the loss and the dispersion of the optical delay line are all precisely managed. The upper limit of bit rate will be restricted by the recovery time of semiconductor optical amplifier (SOA) finally.

  14. All-optical quantum random bit generation from intrinsically binary phase of parametric oscillators.

    PubMed

    Marandi, Alireza; Leindecker, Nick C; Vodopyanov, Konstantin L; Byer, Robert L

    2012-08-13

    We demonstrate a novel all-optical quantum random number generator (RNG) based on above-threshold binary phase state selection in a degenerate optical parametric oscillator (OPO). Photodetection is not a part of the random process, and no post processing is required for the generated bit sequence. We show that the outcome is statistically random with 99% confidence, and verify that the randomness is due to the phase of initiating photons generated through spontaneous parametric down conversion of the pump, with negligible contribution of classical noise sources. With the use of micro- and nanoscale OPO resonators, this technique offers a promise for simple, robust, and high-speed on-chip all-optical quantum RNGs. PMID:23038574

  15. All-optical code routing in interconnected optical CDMA and WDM ring networks.

    PubMed

    Deng, Yanhua; Fok, Mable P; Prucnal, Paul R; Wang, Ting

    2010-11-01

    We propose an all-optical hybrid network composed of optical code division multiple access (CDMA) rings interconnecting through a reconfigurable wavelength division multiplexing (WDM) metro area ring. This network retains the advantages of both the optical CDMA and WDM techniques, including asynchronous access and differentiated quality of service, while removing the hard limit on the number of subscribers and increasing network flexibility. The all-optical network is enabled by using nonlinear optical loop mirrors in an add/drop router (ADR) that performs code conversion, dropping, and switching asynchronously. We experimentally demonstrate the functionalities of the ADR in the proposed scheme asynchronously and obtain error-free performance. The bit-error rate measurements show acceptable power penalties for different code routes. PMID:21042372

  16. Silicon Photonics: All-Optical Devices for Linear and Nonlinear Applications

    NASA Astrophysics Data System (ADS)

    Driscoll, Jeffrey B.

    are shown to contribute no time-averaged momentum. Furthermore, the vectoral modal components, in conjunction with the tensoral nature of the third-order susceptibility of Si, lead to nonlinear properties which are dependent on waveguide orientation with respect to the Si parent crystal and the construction of the modal electric field components. This consideration is used to maximize effective nonlinearity and realize nonlinear Kerr gratings along specific waveguide trajectories. Tight optical confinement leads to a natural enhancement of the intrinsically large effective nonlinearty of Si waveguides, and in fact, the effective nonlinearty can be made to be almost 106 times greater in Si waveguides than that of standard single-mode fiber. Such a large nonlinearity motivates chip-scale all-optical signal processing techniques. Wavelength conversion by both four-wave-mixing (FWM) and cross-phase-modulation (XPM) will be discussed, including a technique that allows for enhanced broadband discrete FWM over arbitrary spectral spans by modulating both the linear and nonlinear waveguide properties through periodic changes in waveguide geometry. This quasi-phase-matching approach has very real applications towards connecting mature telecom sources detectors and components to other spectral regimes, including the mid-IR. Other signal processing techniques such as all-optical modulation format conversion via XPM will also be discussed. This thesis will conclude by looking at ways to extend the bandwidth capacity of Si waveguide interconnects on chip. As the number of processing cores continues to scale as a means for computational performance gains, on-chip link capacity will become an increasingly important issue. Metallic traces have severe limitations and are envisioned to eventually bow to integrated photonic links. The aggregate bandwidth supported by a single waveguide link will therefore become a crucial consideration as integrated photonics approaches the CPU. One way

  17. All-optical SOA latch fail-safe alarm system

    NASA Astrophysics Data System (ADS)

    McAulay, Alastair D.

    2004-11-01

    Emergency alarm systems, for example, that switch off critical processes in process plant, are vulnerable to deliberate or accidental sabotage through coupling of electromagnetic pulses (EMP) to wires and/or from sparks due to broken wires. A proposed system significantly reduces vulnerability by using a fast all-optical latch in conjunction with an optical sensor and optical fibers. Sparks cannot be created on breaking an optical beam and electromagnetic field transients have negligible effect on optical signals. The optical latch uses optical semiconductor amplifiers (SOAs) configured to form a flip-flop. The flip-flop latches after the occurrence of an intrusion that may be as short as a few nanoseconds, much faster than most environmental changes occur. Detection of an emergency or any break in connections causes the light to drop, triggering the alarm. Computer simulation shows that the all-optical latch is fast and effective.

  18. All-optical switching in optically induced nonlinear waveguide couplers

    SciTech Connect

    Diebel, Falko Boguslawski, Martin; Rose, Patrick; Denz, Cornelia; Leykam, Daniel; Desyatnikov, Anton S.

    2014-06-30

    We experimentally demonstrate all-optical vortex switching in nonlinear coupled waveguide arrays optically induced in photorefractive media. Our technique is based on multiplexing of nondiffracting Bessel beams to induce various types of waveguide configurations. Using double- and quadruple-well potentials, we demonstrate precise control over the coupling strength between waveguides, the linear and nonlinear dynamics and symmetry-breaking bifurcations of guided light, and a power-controlled optical vortex switch.

  19. All-optical modulation in wavelength-sized epsilon-near-zero media.

    PubMed

    Ciattoni, Alessandro; Marini, Andrea; Rizza, Carlo

    2016-07-01

    We investigate the interaction of two pulses (pump and probe) scattered by a nonlinear epsilon-near-zero (ENZ) slab whose thickness is comparable with the ENZ wavelength. We show that when the probe has a narrow spectrum localized around the ENZ wavelength, its transmission is dramatically affected by the intensity of the pump. Conversely, if the probe is not in the ENZ regime, its propagation is not noticeably affected by the pump. Such all-optical modulation is due to the oversensitive character of the ENZ regime, and it is so efficient that it even occurs in a wavelength thick slab. PMID:27367112

  20. Making Friends with an Extra-Terrestrial: Conversation Skills and Friendship Formation in Young Children.

    ERIC Educational Resources Information Center

    Parker, Jeffrey G.; Gottman, John M.

    A novel paradigm was developed and two studies conducted to test the contribution of six conversational skills to children's friendship formation. In study 1, 4- and 5-year-olds individually played for 30 minutes with a 2-foot-tall talking doll. The doll contained a wireless hidden receiver/speaker enabling a concealed female assistant to converse…

  1. Format conversion between CAD data and GIS data based on ArcGIS

    NASA Astrophysics Data System (ADS)

    Xie, Qingqing; Wei, Bo; Zhang, Kailin; Wang, Zhichao

    2015-12-01

    To make full use of the data resources and realize a sharing for the different types of data in different industries, a method of format conversion between CAD data and GIS data based on ArcGIS was proposed. To keep the integrity of the converted data, some key steps to process CAD data before conversion were made in AutoCAD. For examples, deleting unnecessary elements such as title, border and legend avoided the appearance of unnecessary elements after conversion, as layering data again by a national standard avoided the different types of elements to appear in a same layer after conversion. In ArcGIS, converting CAD data to GIS data was executed by the correspondence of graphic element classification between AutoCAD and ArcGIS. In addition, an empty geographic database and feature set was required to create in ArcGIS for storing the text data of CAD data. The experimental results show that the proposed method avoids a large amount of editing work in data conversion and maintains the integrity of spatial data and attribute data between before and after conversion.

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

    PubMed

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

    2015-04-01

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

  3. In-fiber all-optical fractional differentiator.

    PubMed

    Cuadrado-Laborde, C; Andrés, M V

    2009-03-15

    We demonstrate that an asymmetrical pi phase-shifted fiber Bragg grating operated in reflection can provide the required spectral response for implementing an all-optical fractional differentiator. There are different (but equivalent) ways to design it, e.g., by using different gratings lengths and keeping the same index modulation depth at both sides of the pi phase shift, or vice versa. Analytical expressions were found relating the fractional differentiator order with the grating parameters. The device shows a good accuracy calculating the fractional time derivatives of the complex field of an arbitrary input optical waveform. The introduced concept is supported by numerical simulations. PMID:19282948

  4. Realization of an all optical exciton-polariton router

    NASA Astrophysics Data System (ADS)

    Marsault, Félix; Nguyen, Hai Son; Tanese, Dimitrii; Lemaître, Aristide; Galopin, Elisabeth; Sagnes, Isabelle; Amo, Alberto; Bloch, Jacqueline

    2015-11-01

    We report on the experimental realization of an all optical router for exciton-polaritons. This device is based on the design proposed by Flayac and Savenko [Appl. Phys. Lett. 103, 201105 (2013)], in which a zero-dimensional island is connected through tunnel barriers to two periodically modulated wires of different periods. Selective transmission of polaritons injected in the island, into either of the two wires, is achieved by tuning the energy of the island state across the band structure of the modulated wires. We demonstrate routing of ps polariton pulses using an optical control beam which controls the energy of the island quantum states, thanks to polariton-exciton interactions.

  5. All-optical processing in coherent nonlinear spectroscopy

    SciTech Connect

    Oron, Dan; Dudovich, Nirit; Silberberg, Yaron

    2004-08-01

    In spectroscopy, the fingerprint of a substance is usually comprised of a sequence of spectral lines with characteristic frequencies and strengths. Identification of substances often involves postprocessing, where the measured spectrum is compared with tabulated fingerprint spectra. Here we suggest a scheme for nonlinear spectroscopy, where, through coherent control of the nonlinear process, the information from the entire spectrum can be practically collected into a single coherent entity. We apply this for all-optical analysis of coherent Raman spectra and demonstrate enhanced detection and effective background suppression using coherent processing.

  6. Realization of an all optical exciton-polariton router

    SciTech Connect

    Marsault, Félix; Nguyen, Hai Son; Tanese, Dimitrii; Lemaître, Aristide; Galopin, Elisabeth; Sagnes, Isabelle; Amo, Alberto

    2015-11-16

    We report on the experimental realization of an all optical router for exciton-polaritons. This device is based on the design proposed by Flayac and Savenko [Appl. Phys. Lett. 103, 201105 (2013)], in which a zero-dimensional island is connected through tunnel barriers to two periodically modulated wires of different periods. Selective transmission of polaritons injected in the island, into either of the two wires, is achieved by tuning the energy of the island state across the band structure of the modulated wires. We demonstrate routing of ps polariton pulses using an optical control beam which controls the energy of the island quantum states, thanks to polariton-exciton interactions.

  7. All-optical flip-flop and control methods thereof

    DOEpatents

    Maywar, Drew; Agrawal, Govind P.

    2010-03-23

    Embodiments of the invention pertain to remote optical control of holding beam-type, optical flip-flop devices, as well as to the devices themselves. All-optical SET and RE-SET control signals operate on a cw holding beam in a remote manner to vary the power of the holding beam between threshold switching values to enable flip-flop operation. Cross-gain modulation and cross-polarization modulation processes can be used to change the power of the holding beam.

  8. All-optical biomolecular parallel logic gates with bacteriorhodopsin.

    PubMed

    Sharma, Parag; Roy, Sukhdev

    2004-06-01

    All-optical two input parallel logic gates with bacteriorhodopsin (BR) protein have been designed based on nonlinear intensity-induced excited-state absorption. Amplitude modulation of a continuous wave (CW) probe laser beam transmission at 640 nm corresponding to the peak absorption of O intermediate state through BR, by a modulating CW pump laser beam at 570 nm corresponding to the peak absorption of initial BR state has been analyzed considering all six intermediate states in its photocycle using the rate equation approach. The transmission characteristics have been shown to exhibit a dip, which is sensitive to normalized small-signal absorption coefficient (beta), rate constants of O and N intermediate states and absorption of the O state at 570 nm. There is an optimum value of beta for a given pump intensity range for which maximum modulation can be achieved. It is shown that 100% modulation can be achieved if the initial state of BR does not absorb the probe beam. The results have been used to design low-power all-optical parallel NOT, AND, OR, XNOR, and the universal NAND and NOR logic gates for two cases: 1) only changing the output threshold and 2) considering a common threshold with different beta values. PMID:15382746

  9. Vibration modal analysis using all-optical photorefractive processing

    SciTech Connect

    Hale, T.; Telschow, K.

    1996-12-31

    A new experimental method for vibration modal analysis based on all- optical photorefractive processing is presented. The method utilizes an optical lock-in approach to measure phase variations in light scattered from optically rough, continuously vibrating surfaces. In this four-wave mixing technique, all-optical processing refers to mixing the object beam containing the frequency modulation due to vibration with a single frequency modulated pump beam in the photorefractive medium that processes the modulated signals. This allows for simple detection of the conjugate wavefront image at a CCD. The conjugate intensity is shown to be a function of the first-order ordinary Bessel function and linearly dependent on the vibration displacement induced phase. Furthermore, the results demonstrate the unique capabilities of the optical lock-in vibration detection technique to measure vibration signals with very narrow bandwidth (< 1 Hz) and high displacement sensitivity (sub-Angstrom). This narrow bandwidth detection can be achieved over a wide frequency range from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The technique is applied to determine the modal characteristics of a rigidly clamped circular disc from 10 kHz to 100 kHz.

  10. All-optical nonlinear plasmonic ring resonator switches

    NASA Astrophysics Data System (ADS)

    Nozhat, N.; Granpayeh, N.

    2014-11-01

    In this paper, all-optical nonlinear plasmonic ring resonator (PRR) switches containing 90o sharp and smooth bends have been proposed and numerically analyzed by the finite-difference time-domain method. Kerr nonlinear self-phase modulation (SPM) and cross-phase modulation (XPM) effects on the switching performance of the device have been studied. By applying a high-power lightwave, the signal can switch from one port to the other port due to the ON/OFF resonant states of the ring. We have shown that by utilizing the XPM effect, the output power ratio is improved by a factor of 2.5 and the required switching power is 31% of that of the case with only the SPM effect. Moreover, by utilizing sharp bend square-shaped ring resonators, the switching power is 10.4% lower than that of the smooth ones. The nonlinear PRR switches are suitable for application in photonic-integrated circuits as all-optical switches because of their nanoscale size and low required switching power.

  11. High Speed All Optical Nyquist Signal Generation and Full-band Coherent Detection

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Fang, Yuan; Chi, Nan

    2014-01-01

    Spectrum efficient data transmission is of key interest for high capacity optical communication systems considering the limited available bandwidth. Transmission of the high speed signal with higher-order modulation formats within the Nyquist bandwidth using coherent detection brings attractive performance advantages. However, high speed Nyquist signal generation with high order modulation formats is challenging. Electrical Nyquist pulse generation is restricted by the limited sampling rate and processor capacities of digital-to-analog convertor devices, while the optical Nyquist signals can provide a much higher symbol rate using time domain multiplexing method. However, most optical Nyquist signals are based on direct detection with simple modulation formats. Here we report the first experimental demonstration of high speed all optical Nyquist signal generation based on Sinc-shaped pulse generation and time-division multiplexing with high level modulation format and full-band coherent detection. Our experiments demonstrate a highly flexible and compatible all optical high speed Nyquist signal generation and detection scheme for future fiber communication systems. PMID:25142269

  12. Graphene based All-Optical Spatial Terahertz Modulator

    PubMed Central

    Wen, Qi-Ye; Tian, Wei; Mao, Qi; Chen, Zhi; Liu, Wei-Wei; Yang, Qing-Hui; Sanderson, Matthew; Zhang, Huai-Wu

    2014-01-01

    We demonstrate an all-optical terahertz modulator based on single-layer graphene on germanium (GOG), which can be driven by a 1.55 μm CW laser with a low-level photodoping power. Both the static and dynamic THz transmission modulation experiments were carried out. A spectrally wide-band modulation of the THz transmission is obtained in a frequency range from 0.25 to 1 THz, and a modulation depth of 94% can be achieved if proper pump power is applied. The modulation speed of the modulator was measured to be ~200 KHz using a 340 GHz carrier. A theoretical model is proposed for the modulator and the calculation results indicate that the enhanced THz modulation is mainly due to the third order nonlinear effect in the optical conductivity of the graphene monolayer. PMID:25491194

  13. All-optical generation of surface plasmons in graphene

    NASA Astrophysics Data System (ADS)

    Constant, T. J.; Hornett, S. M.; Chang, D. E.; Hendry, E.

    2016-02-01

    Surface plasmons in graphene offer a compelling route to many useful photonic technologies. As a plasmonic material, graphene offers several intriguing properties, such as excellent electro-optic tunability, crystalline stability, large optical nonlinearities and extremely high electromagnetic field concentration. As such, recent demonstrations of surface plasmon excitation in graphene using near-field scattering of infrared light have received intense interest. Here we present an all-optical plasmon coupling scheme which takes advantage of the intrinsic nonlinear optical response of graphene. Free-space, visible light pulses are used to generate surface plasmons in a planar graphene sheet using difference frequency wave mixing to match both the wavevector and energy of the surface wave. By carefully controlling the phase matching conditions, we show that one can excite surface plasmons with a defined wavevector and direction across a large frequency range, with an estimated photon efficiency in our experiments approaching 10-5.

  14. All-optical reservoir computer based on saturation of absorption.

    PubMed

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-01

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers. PMID:24921786

  15. All-optical optoacoustic microscope based on wideband pulse interferometry.

    PubMed

    Wissmeyer, Georg; Soliman, Dominik; Shnaiderman, Rami; Rosenthal, Amir; Ntziachristos, Vasilis

    2016-05-01

    Optical and optoacoustic (photoacoustic) microscopy have been recently joined in hybrid implementations that resolve extended tissue contrast compared to each modality alone. Nevertheless, the application of the hybrid technique is limited by the requirement to combine an optical objective with ultrasound detection collecting signal from the same micro-volume. We present an all-optical optoacoustic microscope based on a pi-phase-shifted fiber Bragg grating (π-FBG) with coherence-restored pulsed interferometry (CRPI) used as the interrogation method. The sensor offers an ultra-small footprint and achieved higher sensitivity over piezoelectric transducers of similar size. We characterize the spectral bandwidth of the ultrasound detector and interrogate the imaging performance on phantoms and tissues. We show the first optoacoustic images of biological specimen recorded with π-FBG sensors. We discuss the potential uses of π-FBG sensors based on CRPI. PMID:27128047

  16. High-contrast, all-optical switching in bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Banyal, Ravinder Kumar; Raghavendra Prasad, B.

    2005-09-01

    We report experiments with nonlinear-absorption-based, high-contrast, all-optical switching in photochromic bacteriorhodopsin (BR) films. The switching action is accomplished by control of the transmission of a weak probe beam through a BR sample with the help of strong pump beam illumination at 532 nm wavelength. We found that the switching properties of BR films depend on several experimentally controllable parameters such as probe wavelength, pump beam intensity, and excitation rate. A comparative study of the switching behavior and other parameters of practical use was carried out at three probe wavelengths (543, 594, and 633 nm) and various beam powers and pump excitation rates. The results are presented for commercially available wild-type and D96N variant BR films.

  17. High-contrast, all-optical switching in bacteriorhodopsin films.

    PubMed

    Banyal, Ravinder Kumar; Prasad, B Raghavendra

    2005-09-10

    We report experiments with nonlinear-absorption-based, high-contrast, all-optical switching in photochromic bacteriorhodopsin (BR) films. The switching action is accomplished by control of the transmission of a weak probe beam through a BR sample with the help of strong pump beam illumination at 532 nm wavelength. We found that the switching properties of BR films depend on several experimentally controllable parameters such as probe wavelength, pump beam intensity, and excitation rate. A comparative study of the switching behavior and other parameters of practical use was carried out at three probe wavelengths (543, 594, and 633 nm) and various beam powers and pump excitation rates. The results are presented for commercially available wild-type and D96N variant BR films. PMID:16161665

  18. Generalized model for all-optical light modulation in bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Singh, C. P.; Reddy, K. P. J.

    2001-10-01

    We present a generalized model for the photochemical cycle of bacteriorhodopsin (bR) protein molecule. Rate equations have been solved for the detailed light-induced processes in bR for its nine states: B→K↔L↔MI→MII↔N↔O↔P→Q→B. The complete steady-state intensity-induced population densities in various states of the molecule have been computed to obtain a general, exact, and analytical expression for the nonlinear absorption coefficient for multiple modulation pump laser beams. All-optical light modulation of different probe laser beam transmissions by intensity induced population changes due to one and two modulation laser beams has been analyzed. The proposed model has been shown to accurately model experimental results.

  19. All-Optical Implementation of the Ant Colony Optimization Algorithm

    NASA Astrophysics Data System (ADS)

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I.; Soci, Cesare

    2016-05-01

    We report all-optical implementation of the optimization algorithm for the famous “ant colony” problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems.

  20. All-Optical Implementation of the Ant Colony Optimization Algorithm.

    PubMed

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I; Soci, Cesare

    2016-01-01

    We report all-optical implementation of the optimization algorithm for the famous "ant colony" problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems. PMID:27222098

  1. All-Optical Implementation of the Ant Colony Optimization Algorithm

    PubMed Central

    Hu, Wenchao; Wu, Kan; Shum, Perry Ping; Zheludev, Nikolay I.; Soci, Cesare

    2016-01-01

    We report all-optical implementation of the optimization algorithm for the famous “ant colony” problem. Ant colonies progressively optimize pathway to food discovered by one of the ants through identifying the discovered route with volatile chemicals (pheromones) secreted on the way back from the food deposit. Mathematically this is an important example of graph optimization problem with dynamically changing parameters. Using an optical network with nonlinear waveguides to represent the graph and a feedback loop, we experimentally show that photons traveling through the network behave like ants that dynamically modify the environment to find the shortest pathway to any chosen point in the graph. This proof-of-principle demonstration illustrates how transient nonlinearity in the optical system can be exploited to tackle complex optimization problems directly, on the hardware level, which may be used for self-routing of optical signals in transparent communication networks and energy flow in photonic systems. PMID:27222098

  2. Production and all-optical deceleration of molecular beams

    NASA Astrophysics Data System (ADS)

    Chen, Gary; Jayich, Andrew; Long, Xueping; Ransford, Anthony; Campbell, Wesley

    2015-05-01

    Ultracold molecules open up new opportunities in many areas of study, including many-body physics, quantum chemistry, quantum information, and precision measurements. Current methods cannot easily address the spontaneous decay of molecules into dark states without an amalgam of repump lasers. We present an alternative method to produce cold molecules. A cryogenic buffer gas beam (CBGB) is used to create an intense, slow, cold source of molecules. By using a CBGB for the production, we can quench vibrational modes that cannot be addressed with optical methods. This is then followed by an all-optical scheme using a single ultra-fast laser to decelerate the molecules and a continuous wave laser to cool the species. We have started experiments with strontium monohydride (SrH), but the proposed method should be applicable to a wide range of molecular species.

  3. Self-organized plasmonic metasurfaces for all-optical modulation

    NASA Astrophysics Data System (ADS)

    Della Valle, G.; Polli, D.; Biagioni, P.; Martella, C.; Giordano, M. C.; Finazzi, M.; Longhi, S.; Duò, L.; Cerullo, G.; Buatier de Mongeot, F.

    2015-06-01

    We experimentally demonstrate a self-organized metasurface with a polarization dependent transmittance that can be dynamically controlled by optical means. The configuration consists of tightly packed plasmonic nanowires with a large dispersion of width and height produced by the defocused ion-beam sputtering of a thin gold film supported on a silica glass. Our results are quantitatively interpreted according to a theoretical model based on the thermomodulational nonlinearity of gold and a finite-element numerical analysis of the absorption and scattering cross-sections of the nanowires. We found that the polarization sensitivity of the metasurface can be strongly enhanced by pumping with ultrashort laser pulses, leading to potential applications in ultrafast all-optical modulation and switching of light.

  4. Bandwidth analysis of all-optical turbo-switch

    NASA Astrophysics Data System (ADS)

    Zhou, Peng; Yang, Xuelin; Hu, Xiaonan; Hu, Weisheng

    2015-01-01

    We propose and develop a frequency-domain model to analyze the bandwidth of all-optical turbo-switch. The model has taken the spatial inhomogeneity of semiconductor optical amplifier (SOA) into consideration for the first time. The simulations based on the model show that the 3-dB bandwidth of turbo-switch could reach up to ~270 GHz when the second SOA is oversaturated. However, the overshoot will be higher, which may result in the distortion of the output signal. There is a trade-off between the bandwidth and the flatness of frequency response characteristics for turbo-switch operation. In addition, the optimum position of the delay-interferometer (DI) is investigated, showing that the level of the overshoot is relatively lower if the DI is placed between the two SOAs.

  5. Microscopic model for all optical switching in ferromagnets

    NASA Astrophysics Data System (ADS)

    Cornelissen, T. D.; Córdoba, R.; Koopmans, B.

    2016-04-01

    The microscopic mechanism behind the all optical switching (AOS) in ferromagnets has triggered intense scientific debate. Here, the microscopic three-temperature model is utilized to describe AOS in a perpendicularly magnetized ferromagnetic Co/Pt system. We demonstrate that AOS in such a ferromagnet can be explained with the Inverse Faraday Effect (IFE). The influence of the strength and lifetime of the IFE induced field pulse on the switching process are investigated. We found that because of strong spin-orbit coupling, the minimal lifetime of the IFE needed to obtain switching is of the order of 0.1 ps, which is shorter than previously assumed. Moreover, spatial images of the domain pattern after AOS in Co/Pt, as well as their dependence on applying an opposite magnetic field, are qualitatively reproduced.

  6. An All-Optical Event Horizon in an Optical Analogue of a Laval Nozzle

    NASA Astrophysics Data System (ADS)

    Elazar, Moshe; Bar-Ad, Shimshon; Fleurov, Victor; Schilling, Rolf

    The formal analogy between the propagation of coherent light in a medium with Kerr nonlinearity and the flow of a dissipationless liquid is exploited in a demonstration of an all-optical event horizon in an optical analogue of the aeronautical Laval nozzle. This establishes a unique experimental platform, in which one can observe and study very unusual dynamics of classical and quantum fluctuations, and in particular an analogue of the Hawking radiation emitted by astrophysical black holes. We present a detailed theoretical analysis of these dynamics, and demonstrate experimentally the formation of such an event horizon in a suitably-shaped waveguide structure.

  7. Large-scale photonic integration for advanced all-optical routing functions

    NASA Astrophysics Data System (ADS)

    Nicholes, Steven C.

    Advanced InP-based photonic integrated circuits are a critical technology to manage the increasing bandwidth demands of next-generation all-optical networks. Integrating many of the discrete functions required in optical networks into a single device provides a reduction in system footprint and optical losses by eliminating the fiber coupling junctions between components. This translates directly into increased system reliability and cost savings. Although many key network components have been realized via InP-based monolithic integration over the years, truly large-scale photonic ICs have only recently emerged in the marketplace. This lag-time has been mostly due to historically low device yields. In all-optical routing applications, large-scale photonic ICs may be able to address two of the key roadblocks associated with scaling modern electronic routers to higher capacities---namely, power and size. If the functions of dynamic wavelength conversion and routing are moved to the optical layer, we can eliminate the need for power-hungry optical-to-electrical (O/E) and electrical-to-optical (E/O) data conversions at each router node. Additionally, large-scale photonic ICs could reduce the footprint of such a system by combining the similar functions of each port onto a single chip. However, robust design and manufacturing techniques that will enable high-yield production of these chips must be developed. In this work, we demonstrate a monolithic tunable optical router (MOTOR) chip consisting of an array of eight 40-Gbps wavelength converters and a passive arrayed-waveguide grating router that functions as the packet-forwarding switch fabric of an all-optical router. The device represents one of the most complex InP photonic ICs ever reported, with more than 200 integrated functional elements in a single chip. Single-channel 40 Gbps wavelength conversion and channel switching using 231-1 PRBS data showed a power penalty as low as 4.5 dB with less than 2 W drive power

  8. All-optical microwave bandpass filter with negative coefficients based on a phase modulator and linearly chirped fiber Bragg gratings.

    PubMed

    Zeng, Fei; Wang, Jun; Yao, Jianping

    2005-09-01

    A novel all-optical microwave bandpass filter with negative coefficients is presented. Positive and negative coefficients are obtained through conversion from phase modulation to intensity modulation by passing the phase-modulated optical carriers through chirped fiber Bragg gratings having group-delay responses with positive and negative slopes. A two-tap transversal microwave filter with one negative coefficient is experimentally implemented. PMID:16190418

  9. All-optical beam control with high speed using image-induced blazed gratings in coherent media

    SciTech Connect

    Zhao, L.; Duan Wenhui; Yelin, S. F.

    2010-07-15

    Based on the theory of electromagnetically induced transparency, we study the formation of all-optical blazed transmission gratings in a coherently driven three-level atomic system using intensity-modulated images in coupling fields. Also, we analyze the feasibility of high-speed (megahertz) modulation for the induced gratings by means of image-bearing flat-top pulse trains. Consequently, continuous-wave probe fields can be efficiently and rapidly deflected in free space. When more sophisticated images are adopted, our scheme can provide further possibilities of all-optical beam splitting and fanning.

  10. Suppression of sludge formation by two-stage hydrocracking of vacuum residue at high conversion

    SciTech Connect

    Mochida, I.; Zhao, X.; Sakanishi, K. )

    1990-12-01

    This paper reports on hydrocracked products from Arabian light vacuum residue at high conversion into distillate ({gt}50%) that were analyzed in order to reveal how sludge formation was suppressed in the two-stage reaction. Although the asphaltene in the starting residue was highly soluble in the starting maltene in spite of is largest molecular weight, single-stage hydrocracking at a higher temperature of 420{degrees}C increased the aromaticity of the asphaltene through extensive deaklylation and dehydrogenation, leading to sludge formation. In contrast, two-stage hydrocracking at 390{degrees}C--3 h/420{degrees}C--1/h accomplished effective depolymerization of the asphaltene, high conversion being achieved without sludge. The carbon aromaticity (f{sub a}) of the produced asphaltene was maintained rather low, although its amount in the product was much the same regardless of the reaction conditions. The heptane-soluble maltenes in the hydrocracked oils exhibited variable dissolving abilities against the asphaltene according to the content and aromaticity of its aromatic fraction, also influencing sludge formation. Hydrocracking produced paraffins through the hydrogenative deaklylation of long-chain alkylbenzenes, decreasing f{sub a} and the dissolving ability of the hydrocracked maltene.

  11. Studies in optical parallel processing. [All optical and electro-optic approaches

    NASA Technical Reports Server (NTRS)

    Lee, S. H.

    1978-01-01

    Threshold and A/D devices for converting a gray scale image into a binary one were investigated for all-optical and opto-electronic approaches to parallel processing. Integrated optical logic circuits (IOC) and optical parallel logic devices (OPA) were studied as an approach to processing optical binary signals. In the IOC logic scheme, a single row of an optical image is coupled into the IOC substrate at a time through an array of optical fibers. Parallel processing is carried out out, on each image element of these rows, in the IOC substrate and the resulting output exits via a second array of optical fibers. The OPAL system for parallel processing which uses a Fabry-Perot interferometer for image thresholding and analog-to-digital conversion, achieves a higher degree of parallel processing than is possible with IOC.

  12. All-optical quantization scheme by slicing the supercontinuum in a chalcogenide horizontal slot waveguide

    NASA Astrophysics Data System (ADS)

    Kang, Shuai; Yuan, Jinhui; Kang, Zhe; Zhang, Xianting; Kang, Xue; Guo, Zheng; Li, Feng; Yan, Binbin; Wang, Kuiru; Sang, Xinzhu; Yu, Chongxiu

    2015-08-01

    In this paper, we propose an integratable spectral quantization scheme for all-optical analog-to-digital conversion (AOADC) by slicing the supercontinuum, which is generated in a chalcogenide (As2S3) horizontal slot waveguide. The numerical simulation results show that a 4-bit quantization resolution is successfully achieved along with a signal-to-noise ratio of 23.96 dB and an effective number of bit (ENOB) of 3.98 bit. The required As2S3 waveguide length and input peak power are only 1.5 cm and 900 mW, respectively, owing to the high nonlinear coefficient of 115.8 W-1/m. It is believed that this proposed scheme can find important applications in the photonic integratable AOADC with low power consumption.

  13. All-optical tunable microwave interference suppression filter based on SOA

    NASA Astrophysics Data System (ADS)

    Xu, Enming; Zhang, Xinliang; Zhou, Lina; Huang, Dexiu

    2008-12-01

    An all-optical filter structure for interference suppression of microwave signals is presented. The filter is based on a recirculating delay line (RDL) loop consisting of a semiconductor optical amplifier (SOA) followed by a tunable narrowband optical filter, and a fiber Bragg grating connected after the RDL loop. Negative tap is generated in wavelength conversion process based on cross-gain modulation of amplified spontaneous emission spectrum of the SOA. A narrow passband filter with negative coefficients and a broadband all-pass filter are synthesized to achieve a narrow notch filter with flat passband which can excise interference with minimal impact on the wanted signal over a wide microwave range. Experimental results show that measured and theoretical frequency responses agree well and the filter is tunable.

  14. All-optical probing of the nonlinear acoustics of a crack.

    PubMed

    Mezil, Sylvain; Chigarev, Nikolay; Tournat, Vincent; Gusev, Vitalyi

    2011-09-01

    Experiments with an all-optical method for the study of the nonlinear acoustics of cracks in solids are reported. Nonlinear acoustic waves are initiated by the absorption of radiation from a pair of laser beams intensity modulated at two different frequencies. The detection of acoustic waves at mixed frequencies, absent in the frequency spectrum of the heating lasers, by optical interferometry or deflectometry provides unambiguous evidence of the elastic nonlinearity of the crack. The high contrast in crack imaging achieved by remote optical monitoring of the nonlinear acoustic processes is due to the strong dependence of the efficiency of optoacoustic conversion on the state of the crack. The highest acoustic nonlinearity is observed in the transitional state of the crack, which is intermediate between the open and the closed ones. PMID:21886240

  15. All-optical nonlinear holographic correlation using bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Thoma, Ralph; Dratz, Michael; Hampp, Norbert

    1995-05-01

    Films made of the halobacterial photochrome bacteriorhodopsin (BR) can be used in a number of holographic real-time applications. Their application as active material in a dual-axis joint- Fourier-transform (DAJFT) real-time correlator was shown recently. The BR films have a strong nonlinear intensity dependence on the light-induced absorption and refractive-index changes. Therefore the holographic diffraction efficiency also shows a nonlinear dependence on the writing intensity. We investigate the effect of this nonlinearity on the result of the correlation process in a bacteriorhodopsin-based DAJFT correlator. Numerical models supporting the experimental observations are presented. It was found that the BR film combines the holographic function for most objects with that of a spatial bandpass filter, whose center frequency is tuned by the writing intensity. This results in smaller peak widths and a suppression of the sidelobes. BR films allow the application of this nonlinear behavior in real time to the all-optical correlation process.

  16. All-optical broadband ultrasonography of single cells

    PubMed Central

    Dehoux, T.; Ghanem, M. Abi; Zouani, O. F.; Rampnoux, J.-M.; Guillet, Y.; Dilhaire, S.; Durrieu, M.-C.; Audoin, B.

    2015-01-01

    Cell mechanics play a key role in several fundamental biological processes, such as migration, proliferation, differentiation and tissue morphogenesis. In addition, many diseased conditions of the cell are correlated with altered cell mechanics, as in the case of cancer progression. For this there is much interest in methods that can map mechanical properties with a sub-cell resolution. Here, we demonstrate an inverted pulsed opto-acoustic microscope (iPOM) that operates in the 10 to 100 GHz range. These frequencies allow mapping quantitatively cell structures as thin as 10 nm and resolving the fibrillar details of cells. Using this non-invasive all-optical system, we produce high-resolution images based on mechanical properties as the contrast mechanisms, and we can observe the stiffness and adhesion of single migrating stem cells. The technique should allow transferring the diagnostic and imaging abilities of ultrasonic imaging to the single-cell scale, thus opening new avenues for cell biology and biomaterial sciences. PMID:25731090

  17. All-optical active switching in individual semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Piccione, Brian; Cho, Chang-Hee; van Vugt, Lambert K.; Agarwal, Ritesh

    2012-10-01

    The imminent limitations of electronic integrated circuits are stimulating intense activity in the area of nanophotonics for the development of on-chip optical components, and solutions incorporating direct-bandgap semiconductors are important in achieving this end. Optical processing of data at the nanometre scale is promising for circumventing these limitations, but requires the development of a toolbox of components including emitters, detectors, modulators, waveguides and switches. In comparison to components fabricated using top-down methods, semiconductor nanowires offer superior surface properties and stronger optical confinement. They are therefore ideal candidates for nanoscale optical network components, as well as model systems for understanding optical confinement. Here, we demonstrate all-optical switching in individual CdS nanowire cavities with subwavelength dimensions through stimulated polariton scattering, as well as a functional NAND gate built from multiple switches. The device design exploits the strong light-matter coupling present in these nanowires, leading to footprints that are a fraction of those of comparable silicon-based dielectric contrast and photonic crystal devices.

  18. All-optical broadband ultrasonography of single cells

    NASA Astrophysics Data System (ADS)

    Dehoux, T.; Ghanem, M. Abi; Zouani, O. F.; Rampnoux, J.-M.; Guillet, Y.; Dilhaire, S.; Durrieu, M.-C.; Audoin, B.

    2015-03-01

    Cell mechanics play a key role in several fundamental biological processes, such as migration, proliferation, differentiation and tissue morphogenesis. In addition, many diseased conditions of the cell are correlated with altered cell mechanics, as in the case of cancer progression. For this there is much interest in methods that can map mechanical properties with a sub-cell resolution. Here, we demonstrate an inverted pulsed opto-acoustic microscope (iPOM) that operates in the 10 to 100 GHz range. These frequencies allow mapping quantitatively cell structures as thin as 10 nm and resolving the fibrillar details of cells. Using this non-invasive all-optical system, we produce high-resolution images based on mechanical properties as the contrast mechanisms, and we can observe the stiffness and adhesion of single migrating stem cells. The technique should allow transferring the diagnostic and imaging abilities of ultrasonic imaging to the single-cell scale, thus opening new avenues for cell biology and biomaterial sciences.

  19. All-optical photoacoustic microscopy using a MEMS scanning mirror

    NASA Astrophysics Data System (ADS)

    Chen, Sung-Liang; Xie, Zhixing; Ling, Tao; Wei, Xunbin; Guo, L. Jay; Wang, Xueding

    2013-03-01

    It has been studied that a potential marker to obtain prognostic information about bladder cancer is tumor neoangiogenesis, which can be quantified by morphometric characteristics such as microvascular density. Photoacoustic microscopy (PAM) can render sensitive three-dimensional (3D) mapping of microvasculature, providing promise to evaluate the neoangiogenesis that is closely related to the diagnosis of bladder cancer. To ensure good image quality, it is desired to acquire bladder PAM images from its inside via the urethra, like conventional cystoscope. Previously, we demonstrated all-optical PAM systems using polymer microring resonators to detect photoacoustic signals and galvanometer mirrors for laser scanning. In this work, we build a miniature PAM system using a microelectromechanical systems (MEMS) scanning mirror, demonstrating a prototype of an endoscopic PAM head capable of high imaging quality of the bladder. The system has high resolutions of 17.5 μm in lateral direction and 19 μm in the axial direction at a distance of 5.4 mm. Images of printed grids and the 3D structure of microvasculature in animal bladders ex vivo by the system are demonstrated.

  20. All-optical control of ultrafast photocurrents in unbiased graphene

    PubMed Central

    Obraztsov, Petr A.; Kaplas, Tommi; Garnov, Sergey V.; Kuwata-Gonokami, Makoto; Obraztsov, Alexander N.; Svirko, Yuri P.

    2014-01-01

    Graphene has recently become a unique playground for studying light-matter interaction effects in low-dimensional electronic systems. Being of strong fundamental importance, these effects also open a wide range of opportunities in photonics and optoelectronics. In particular, strong and broadband light absorption in graphene allows one to achieve high carrier densities essential for observation of nonlinear optical phenomena. Here, we make use of strong photon-drag effect to generate and optically manipulate ultrafast photocurrents in graphene at room temperature. In contrast to the recent reports on injection of photocurrents in graphene due to external or built-in electric field effects and by quantum interference, we force the massless charge carriers to move via direct transfer of linear momentum from photons of incident laser beam to excited electrons in unbiased sample. Direction and amplitude of the drag-current induced in graphene are determined by polarization, incidence angle and intensity of the obliquely incident laser beam. We also demonstrate that the irradiation of graphene with two laser beams of the same wavelength offers an opportunity to manipulate the photocurrents in time domain. The obtained all-optical control of the photocurrents opens new routes towards graphene based high-speed and broadband optoelectronic devices. PMID:24500084

  1. Quasi-all-optical network extension for submarine cabled observatories

    NASA Astrophysics Data System (ADS)

    Audo, Frederic; Guegan, Mikael; Quintard, Véronique; Perennou, Andre; Le Bihan, Jean; Auffret, Yves

    2011-04-01

    Submarine cabled networks are designed to collect valuable data in geophysics, geochemistry, biology, or oceanography. Unfortunately, the development of such a network is expensive and needs complex subsea infrastructures. Once in place, a cabled network cannot be easily relocated. The current cost of cables and their installation are one of the major obstacles to these networks deployment. On the one hand, these cables are necessary to provide power supply and communication data, and on the other hand they drastically reduce the possibilities to extend the cabled observatory network in order to reach a closed area of significant interest. This is why, to address this issue, we propose a quasi-all-optical architecture to easily extend multidisciplinary cabled networks or to create a dedicated submarine hydrophone or seismometer network. This solution consists of using only a single fiber optic to transmit both the energy, required to supply the instrument, and the data, exchanged between the shore station or equivalent. In this paper, we present our proposed architecture, and we discuss its feasibility thanks to experimental results.

  2. Rapidly Reconfigurable All-Optical Universal Logic Gates

    SciTech Connect

    Goddard, L L; Kallman, J S; Bond, T C

    2006-06-21

    We present designs and simulations for a highly cascadable, rapidly reconfigurable, all-optical, universal logic gate. We will discuss the gate's expected performance, e.g. speed, fanout, and contrast ratio, as a function of the device layout and biasing conditions. The gate is a three terminal on-chip device that consists of: (1) the input optical port, (2) the gate selection port, and (3) the output optical port. The device can be built monolithically using a standard multiple quantum well graded index separate confinement heterostructure laser configuration. The gate can be rapidly and repeatedly reprogrammed to perform any of the basic digital logic operations by using an appropriate analog electrical or optical signal at the gate selection port. Specifically, the same gate can be selected to execute one of the 2 basic unary operations (NOT or COPY), or one of the 6 binary operations (OR, XOR, AND, NOR, XNOR, or NAND), or one of the many logic operations involving more than two inputs. The speed of the gate for logic operations as well as for reprogramming the function of the gate is primarily limited to the small signal modulation speed of a laser, which can be on the order of tens of GHz. The reprogrammable nature of the universal gate offers maximum flexibility and interchangeability for the end user since the entire application of a photonic integrated circuit built from cascaded universal logic gates can be changed simply by adjusting the gate selection port signals.

  3. All-optical regulation of gene expression in targeted cells

    NASA Astrophysics Data System (ADS)

    Wang, Yisen; He, Hao; Li, Shiyang; Liu, Dayong; Lan, Bei; Hu, Minglie; Cao, Youjia; Wang, Chingyue

    2014-06-01

    Controllable gene expression is always a challenge and of great significance to biomedical research and clinical applications. Recently, various approaches based on extra-engineered light-sensitive proteins have been developed to provide optogenetic actuators for gene expression. Complicated biomedical techniques including exogenous genes engineering, transfection, and material delivery are needed. Here we present an all-optical method to regulate gene expression in targeted cells. Intrinsic or exogenous genes can be activated by a Ca2+-sensitive transcription factor nuclear factor of activated T cells (NFAT) driven by a short flash of femtosecond-laser irradiation. When applied to mesenchymal stem cells, expression of a differentiation regulator Osterix can be activated by this method to potentially induce differentiation of them. A laser-induced ``Ca2+-comb'' (LiCCo) by multi-time laser exposure is further developed to enhance gene expression efficiency. This noninvasive method hence provides an encouraging advance of gene expression regulation, with promising potential of applying in cell biology and stem-cell science.

  4. Flexible all-optical frequency allocation of OFDM subcarriers.

    PubMed

    Lowery, Arthur James; Schröder, Jochen; Du, Liang B

    2014-01-13

    We investigate the underlying mechanism that allows OFDM subcarriers in an all-optical OFDM system to be assigned to any optical frequency using an optical filter, even if that frequency is not generated by the comb-line source feeding the filters. We confirm our analysis using simulations, and present experimental results from a 252-subcarrier system that uses a mode-locked laser (MLL) as the comb source and a wavelength selective switch. The experimental results show that there is no correlation between the programmed frequency offset between a subcarrier and nearest comb line, and the received signal quality. Thus, subcarriers could be inserted into unused portions of an optical transmission system's spectrum without restriction on their particular center frequencies. Any percentage of cyclic prefix can be added to the OFDM symbol simply by reprogramming the optical filter to give wider subcarrier frequency spacing than the comb line spacing, which is useful for tailoring the CP to the dispersion of various optical transmission paths, to maximize the spectral efficiency. Finally, the MLL's center frequency need not be locked to a system reference. PMID:24515064

  5. Design of pitch conversion component for formation of multibeam optical recording head

    NASA Astrophysics Data System (ADS)

    Sasaki, Kentaro; Kawamura, Norikazu; Tokumaru, Haruki

    2008-04-01

    We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams.

  6. Design of pitch conversion component for formation of multibeam optical recording head.

    PubMed

    Sasaki, Kentaro; Kawamura, Norikazu; Tokumaru, Haruki

    2008-04-10

    We describe a design of a planar lightwave circuit for parallel information processing using visible light. The circuit serves as a pitch conversion component (PCC) that can align multiple beams close together and easily composes a compact optical system that can project optical spots at a narrow pitch on a certain small plane. From the viewpoint of its application to optical recording, a PCC is designed to have over 50 waveguides according to the fabrication of waveguides for a blue-violet beam. It is analytically confirmed that a PCC contributes to the formation of a multibeam optical recording head with numerous beams. PMID:18404179

  7. The formation and degradation of active species during methanol conversion over protonated zeotype catalysts.

    PubMed

    Olsbye, U; Svelle, S; Lillerud, K P; Wei, Z H; Chen, Y Y; Li, J F; Wang, J G; Fan, W B

    2015-10-21

    The methanol to hydrocarbon (MTH) process provides an efficient route for the conversion of carbon-based feedstocks into olefins, aromatics and gasoline. Still, there is room for improvements in product selectivity and catalytic stability. This task calls for a fundamental understanding of the formation, catalytic mechanism and degradation of active sites. The autocatalytic feature of the MTH process implies that hydrocarbons are active species on the one hand and deactivating species on the other hand. The steady-state performance of such species has been thoroughly studied and reviewed. However, the mechanism of formation of the initial hydrocarbon species (i.e.; the first C-C bond) and the evolution of active species into deactivating coke species have received less attention. Therefore, this review focuses on the significant progress recently achieved in these two stages by a combination of theoretical calculations, model studies, operando spectroscopy and catalytic tests. PMID:26185806

  8. All-Optical Ultrasound Transducers for High Resolution Imaging

    NASA Astrophysics Data System (ADS)

    Sheaff, Clay Smith

    High frequency ultrasound (HFUS) has increasingly been used within the past few decades to provide high resolution (< 200 mum) imaging in medical applications such as endoluminal imaging, intravascular imaging, ophthalmology, and dermatology. The optical detection and generation of HFUS using thin films offers numerous advantages over traditional piezoelectric technology. Circumvention of an electronic interface with the device head is one of the most significant given the RF noise, crosstalk, and reduced capacitance that encumbers small-scale electronic transducers. Thin film Fabry-Perot interferometers - also known as etalons - are well suited for HFUS receivers on account of their high sensitivity, wide bandwidth, and ease of fabrication. In addition, thin films can be used to generate HFUS when irradiated with optical pulses - a method referred to as Thermoelastic Ultrasound Generation (TUG). By integrating a polyimide (PI) film for TUG into an etalon receiver, we have created for the first time an all-optical ultrasound transducer that is both thermally stable and capable of forming fully sampled 2-D imaging arrays of arbitrary configuration. Here we report (1) the design and fabrication of PI-etalon transducers; (2) an evaluation of their optical and acoustic performance parameters; (3) the ability to conduct high-resolution imaging with synthetic 2-D arrays of PI-etalon elements; and (4) work towards a fiber optic PI-etalon for in vivo use. Successful development of a fiber optic imager would provide a unique field-of-view thereby exposing an abundance of prospects for minimally-invasive analysis, diagnosis, and treatment of disease.

  9. Amorphous silicon thin film for all-optical micromodulator

    NASA Astrophysics Data System (ADS)

    Nigro, Maria Arcangela M.; Cantore, Francesca; Della Corte, Francesco Giuseppe; Summonte, Caterina

    2003-04-01

    Photoinduced absorption by VIS radiation in a-Si:H has been studied in-guide, in order to realise a novel all-optical waveguide micromodulator for application at 1.3 and 1.55 μm fiber communication wavelengths. In a-Si:H the photoinduced effects and the NIR absorption both involve dangling bonds states. The density of these states, deep in the gap, can be varied with doping. Therefore three waveguide prototypes have been fabricated by Plasma Enhanced Chemical Vapour Deposition on a silicon wafer. Their structure consist of a a-Si:H/SiO2 stack where the a-Si:H cores have different doping. The upper cladding is air. Optical measures on the core materials and signal transmission analysis in-guide at bit rates up to 200 kBit/s have been carried out. The excitation source of the VIS pump system for in-guide analysis consisted of simple, low cost AlInGaP LED"s controlled by a pulse generator. The pump and probe measures have been performed with different pump wavelengths and by varying the illumination intensity. LED"s with wavelengths of 644, 612, 590 and 571 nm have been alternatively used. For each pump wavelength, the light intensity was varied between 0,15 and 0,85 mW/mm2. The results confirms that the optical modulation of the NIR signal enhances at high doping levels and for longer wavelengths. The modulation speed is probably limited by recombination phenomena.

  10. Phase-coherent all-optical frequency division by three

    SciTech Connect

    Lee, Dong-Hoon; Klein, Marvin E.; Meyn, Jan-Peter; Wallenstein, Richard; Gross, Petra; Boller, Klaus-Jochen

    2003-01-01

    The properties of all-optical phase-coherent frequency division by 3, based on a self-phase-locked continuous-wave (cw) optical parametric oscillator (OPO), are investigated theoretically and experimentally. The frequency to be divided is provided by a diode laser master-oscillator power-amplifier system operated at a wavelength of 812 nm and used as the pump source of the OPO. Optical self-phase-locking of the OPO signal and idler waves is achieved by mutual injection locking of the signal wave and the intracavity frequency-doubled idler wave. The OPO process and the second-harmonic generation of the idler wave are simultaneously phase matched through quasi-phase-matching using two periodically poled sections of different period manufactured within the same LiNbO{sub 3} crystal. An optical self-phase-locking range of up to 1 MHz is experimentally observed. The phase coherence of frequency division by three is measured via the phase stability of an interference pattern formed by the input and output waves of the OPO. The fractional frequency instability of the divider is measured to be smaller than 7.6x10{sup -14} for a measurement time of 10 s (resolution limited). The self-phase-locking characteristics of the cw OPO are theoretically investigated by analytically solving the coupled field equations in the steady-state regime. For the experimental parameters of the OPO, the calculations predict a locking range of 1.3 MHz and a fractional frequency instability of 1.6x10{sup -15}, in good agreement with the experimental results.

  11. Description of all-optical network test bed and applications

    NASA Astrophysics Data System (ADS)

    Marquis, Douglas; Castagnozzi, Daniel M.; Hemenway, B. R.; Parikh, Salil A.; Stevens, Mark L.; Swanson, Eric A.; Thomas, Robert E.; Ozveren, C.; Kaminow, Ivan P.

    1995-12-01

    We describe an all-optical network testbed deployed in the Boston metropolitan area, and some of the experimental applications running over the network. The network was developed by a consortium of AT&T Bell Laboratories, Digital Equipment Corporation, and Massachusetts Institute of Technology under a grant from ARPA. The network is an optical WDM system organized as a hierarchy consisting of local, metropolitan, and wide area nodes that support optical broadcast and routing modes. Frequencies are shared and reused to enhance network scalability. Electronic access is provided through optical terminals that support multiple services having data rates between 10 Mbps/user and 10 Gbps/user. Novel components used to implement the network include fast-tuning 1.5 micrometers distributed Bragg reflector lasers, passive wavelength routers, and broadband optical frequency converters. An overlay control network implemented at 1.3 micrometers allows reliable out-of-band control and standardized network management of all network nodes. We have created interfaces between the AON and commercially available electronic circuit-switched and packet-switched networks. We will report on network applications that can dynamically allocate optical bandwidth between electronic packet-switches based on the offered load presented by users, without requiring interfaces between users and the AON control system. We will also describe video and telemedicine applications running over the network. We have demonstrated an audio/video codec that is directly interfaced to the optical network, and is capable of transmitting high-rate digitized video signals for broadcast or videoconferencing applications. We have also demonstrated a state-of-the-art radiological workstation that uses the AON to transport 2000 X 2000 X 16 bit images from a remote image server.

  12. All-optical metamaterial modulators: Fabrication, simulation and characterization

    NASA Astrophysics Data System (ADS)

    Ku, Zahyun

    Artificially structured composite metamaterials consist of sub-wavelength sized structures that exhibit unusual electromagnetic properties not found in nature. Since the first experimental verification in 2000, metamaterials have drawn considerable attention because of their broad range of potential applications. One of the most attractive features of metamaterials is to obtain negative refraction, termed left-handed materials or negative-index metamaterials, over a limited frequency band. Negative-index metamaterials at near infrared wavelength are fabricated with circular, elliptical and rectangular holes penetrating through metal/dielectric/metal films. All three negative-index metamaterial structures exhibit similar figure of merit; however, the transmission is higher for the negative-index metamaterial with rectangular holes as a result of an improved impedance match with the substrate-superstrate (air-glass) combination. In general, the processing procedure to fabricate the fishnet structured negative-index metamaterials is to define the hole-size using a polymetric material, usually by lithographically defining polymer posts, followed by deposition of the constitutive materials and dissolution of the polymer (liftoff processing). This processing (fabrication of posts: multi-layer deposition: liftoff) often gives rise to significant sidewall-angle because materials accumulate on the tops of the posts that define the structure, each successive film deposition has a somewhat larger aperture on the bottom metamaterial film, giving rise to a nonzero sidewall-angle and to optical bianisotropy. Finally, we demonstrate a nanometer-scale, sub-picosecond metamaterial device capable of over terabit/second all-optical communication in the near infrared spectrum. We achieve a 600 fs device response by utilizing a regime of sub-picosecond carrier dynamics in amorphous silicon and ˜70% modulation in a path length of only 124 nm by exploiting the strong nonlinearities in

  13. EGCG Inhibited Lipofuscin Formation Based on Intercepting Amyloidogenic β-Sheet-Rich Structure Conversion

    PubMed Central

    Cai, Shuxian; Yang, Heng; Zeng, Kewu; Zhang, Jing; Zhong, Ni; Wang, Yingzi; Ye, Jing; Tu, Pengfei; Liu, Zhonghua

    2016-01-01

    Background Lipofuscin (LF) is formed during lipid peroxidation and sugar glycosylation by carbonyl-amino crosslinks with biomacrolecules, and accumulates slowly within postmitotic cells. The environmental pollution, modern dietary culture and lifestyle changes have been found to be the major sources of reactive carbonyl compounds in vivo. Irreversible carbonyl-amino crosslinks induced by carbonyl stress are essentially toxiferous for aging-related functional losses in modern society. Results show that (-)-epigallocatechin gallate (EGCG), the main polyphenol in green tea, can neutralize the carbonyl-amino cross-linking reaction and inhibit LF formation, but the underlying mechanism is unknown. Methods and Results We explored the mechanism of the neutralization process from protein, cell, and animal levels using spectrofluorometry, infrared spectroscopy, conformation antibodies, and electron microscopy. LF demonstrated an amyloidogenic β-sheet-rich with antiparallel structure, which accelerated the carbonyl-amino crosslinks formation and disrupted proteolysis in both PC12 cells and D-galactose (D-gal)-induced brain aging mice models. Additionally, EGCG effectively inhibited the formation of the amyloidogenic β-sheet-rich structure of LF, and prevented its conversion into toxic and on-pathway aggregation intermediates, thereby cutting off the carbonyl-amino crosslinks. Conclusions Our study indicated that the amyloidogenic β-sheet structure of LF may be the core driving force for carbonyl-amino crosslinks further formation, which mediates the formation of amyloid fibrils from native state of biomacrolecules. That EGCG exhibits anti-amyloidogenic β-sheet-rich structure properties to prevent the LF formation represents a novel strategy to impede the development of degenerative processes caused by ageing or stress-induced premature senescence in modern environments. PMID:27030967

  14. Theoretical Study of SOA-Based Wavelength Conversion with NRZ and RZ Format at 40 Gb/s

    NASA Astrophysics Data System (ADS)

    Dong, Jian-Ji; Zhang, Xin-Liang; Fu, Song-Nian; Shum, Ping; Huang, De-Xiu

    2007-04-01

    We theoretically discuss 40 Gb/s semiconductor optical amplifier (SOA)-based wavelength conversion (WC) using a detuning optical bandpass filter based on ultrafast dynamic characteristics of SOA. Both the inverted and non-inverted WCs are obtained by shifting the filter central wavelength with respect to the probe wavelength when input data signal is in return-to-zero (RZ) format. However, we can obtain format conversion from nonreturn-to-zero (NRZ) to pseudo-return-to-zero (PRZ) and inverted WC when the input signal is in NRZ format.

  15. All-Optical Quasi-Phase Matching of Frequency Doubling Using Counterpropagating Light

    NASA Astrophysics Data System (ADS)

    Camuccio, Richard; Myer, Rachel; Penfield, Allison; Gagnon, Etienne; Lytle, Amy

    Nonlinear optical frequency conversion is a useful method for creating coherent light sources with unique capabilities. The main challenge for conversion efficiency of processes like frequency doubling is the chromatic dispersion of the nonlinear medium. Successful techniques for correcting the phase mismatch between the different frequencies are often limited by the type of nonlinear medium that may be used. An all-optical method of quasi-phase matching using counterpropagating light has recently been demonstrated for high-order harmonic generation, an extreme nonlinear process. Sequences of counterpropagating pulses are used to interfere with the harmonic generation process periodically, correcting the phase mismatch and boosting efficiency. We report progress on an experimental investigation of the effect of counterpropagating light on the more commonly used low-order nonlinear optical processes. We present data showing the effects of a single counterpropagating pulse on the efficiency of frequency doubling of a Ti:sapphire ultrafast laser oscillator in beta-Barium Borate. Research Corporation for Science Advancement (RCSA), Cottrell College Science Award #21084; Franklin & Marshall Hackman Summer Scholars Program.

  16. Experimental and theoretical investigation of semiconductor optical amplifier (SOA)-based all-optical wavelength converters

    NASA Astrophysics Data System (ADS)

    Dailey, James M.

    Use of fiber-optical networks has increased along with the growing demand for higher data throughputs. As data bandwidths increase, physical switching technologies must also scale accordingly. Optical-electrical-optical (OEO) switching technologies are widely utilized, where incoming optical signals are converted into and processed as electrical signals before conversion back into the optical domain. However, issues such as speed, cost, and power consumption have driven interest in the development of all-optical techniques, where data remains in the optical domain while being processed. Semiconductor optical amplifiers (SOAs) have shown great promise for realizing all-optical technologies. Our work begins with the experimental characterization of SOAs, and we discuss the use of a time-resolved spectroscopy technique. We present a detailed analysis clarifying measurement requirements, though we conclude that this simple technique provides insufficient resolution for characterizing high-speed optical systems. We discuss the measurement theory for spectrograms, which provide high signal-to-noise ratios, excellent temporal resolution, and are sensitive to phase dynamics. We apply the spectrogram measurement to the characterization of an SOA. We develop a system of rate equations for modeling SOA dynamics, beginning with a detailed density matrix analysis providing expressions for gain and chirp without invoking the linewidth-enhancement factor. In accordance with the measurement results, we include a carrier temperature rate calculation in order to capture ultrafast dynamics. The traveling wave partial differential equations are solved so that both forward and reverse propagating signals are accurately modeled, and the results show good agreement with the spectrogram measurement. We identify the free-carrier plasma and the asymmetrical broadening terms in the real and imaginary parts of the refractive index as driving factors in the relatively larger ultrafast response

  17. Formation, molecular structure, and morphology of humins in biomass conversion: influence of feedstock and processing conditions.

    PubMed

    van Zandvoort, Ilona; Wang, Yuehu; Rasrendra, Carolus B; van Eck, Ernst R H; Bruijnincx, Pieter C A; Heeres, Hero J; Weckhuysen, Bert M

    2013-09-01

    Neither the routes through which humin byproducts are formed, nor their molecular structure have yet been unequivocally established. A better understanding of the formation and physicochemical properties of humins, however, would aid in making biomass conversion processes more efficient. Here, an extensive multiple-technique-based study of the formation, molecular structure, and morphology of humins is presented as a function of sugar feed, the presence of additives (e.g., 1,2,4-trihydroxybenzene), and the applied processing conditions. Elemental analyses indicate that humins are formed through a dehydration pathway, with humin formation and levulinic acid yields strongly depending on the processing parameters. The addition of implied intermediates to the feedstocks showed that furan and phenol compounds formed during the acid-catalyzed dehydration of sugars are indeed included in the humin structure. IR spectra, sheared sum projections of solid-state 2DPASS (13) C NMR spectra, and pyrolysis GC-MS data indicate that humins consist of a furan-rich polymer network containing different oxygen functional groups. The structure is furthermore found to strongly depend on the type of feedstock. A model for the molecular structure of humins is proposed based on the data presented. PMID:23836679

  18. Formation and corrosion inhibition mechanisms of chromate conversion coatings on aluminum and AA2024-T3

    NASA Astrophysics Data System (ADS)

    Zhang, Wenping

    Chromate conversion coatings (CCCs) are applied to aluminum alloys to enhance their resistance to localized corrosion and to increase paint adhesion. However, chromate is toxic and suspected carcinogen. To develop environmentally friendly alternative coatings, a detailed and accurate understanding of CCC formation and breakdown is needed. Several studies on CCC formation and breakdown were conducted in this regard. A first set of experiments was aimed at studying CCC formation and breakdown on 25-element Al electrode arrays. Results from coating formation experiments show that the coating process occurs in two stages. The first stage is characterized by intense electrochemical activity on the array and last from 20 to 30 seconds. The second stage occurs under electrochemical quiescence and little measurable current flows among elements in the electrode array. Raman spectroscopy shows that the coating continues to adsorb Cr6+. Anodic polarization of conversion coated arrays in chloride solutions led to several important findings. First, it was found that pitting potential increases as coating time increases through both stage one and stage two coating formation. These results also show that changes in coating structure and chemistry occur during the electrochemically quiescent second stage of coating formation. Further analysis showed that pitting potentials were higher on electrode elements that were net cathodes during first stage CCC formation than on electrode elements that were net anodes. Results also showed that the supplemental ingredients, NaF and K3Fe(CN)6, are essential to CCC formation and contribute greatly to increasing the corrosion protection provided by the coating. A second set of experiments was aimed at characterizing the effect of aging on CCC structure and properties. CCCs are dynamic due to the fact that they continue to polymerize after they are removed from the coating bath. Using cathodic polarization experiments carried out in aerated

  19. Dynamic formation of zeolite synthesized from fly ash by alkaline hydrothermal conversion.

    PubMed

    Zhang, ZhiJian; Li, Jiangli; Li, Hongyi; Wang, Hang; Zhu, Jun; He, Qiang

    2013-11-01

    This study was designed to characterize the dynamic formation of zeolite synthesized from fly ash (ZFA) and to identify the zeolitization mechanisms during a 160-h-long hydrothermal alkaline conversion at 95°C by using fly ash (FA) samples collected from four typical thermoelectric power plants in China, with the purpose of improving ZFA quality. The process of synthesizing ZFA can be fundamentally divided into five stages: induction stage (0-0.5 h), accelerating dissolution stage (0.5-12 h), nucleation and/or crystallization stage (12-24 h), crystal growth stage (24-72 h) and crystal transformation stage (72-160 h). The crystal growth stage determined the quality of zeolite crystallization, coupled with functions of re-assembling the silicon-aluminium tetrahedral network and developing submicro- and/or nanometer microstructure. A 48-h-long hydrothermal conversion generated ZFAs that had a greater specific surface area (26.0-89.4 times) and cation exchange capacity (29.6-71.0 times) than FA, which successfully sequestrated 41-95% of ammonium and 75-98% of phosphate from swine manure. However, over-reaction resulted in more stable hydroxysodalite and/or sodalite, surface agglomeration and cracking, and energy wasting. This work suggests that the reuse of recycled synthesis materials should occur during the fourth step (24-72 h). PMID:24025368

  20. Conversation Salons: A Flexible Format for Open Discourse in Dental Education.

    PubMed

    Quick, Karin K

    2016-04-01

    A series of conversation salons was created at the University of Minnesota School of Dentistry as an innovative format with the objective of engaging students, faculty, staff, and practitioners in discussion to promote reflection. The aim of this study was to explore the nature of students' abilities in the salons to connect experiences through reflection and apply what they learned to practice. Reflective essays (written during the summer and fall semesters of 2014) from 108 fourth-year dental students (all members of the Class of 2015) were read and assessed for the nature of reflection, number of connections, references to the past, applications to the future, and use of examples. For analysis, the theoretical works of Schön and Mezirow provided a useful framework. Overall, the results showed that the participants found the salon experience to be positive, and student participation was strong. When asked about learning, the most frequent responses were topic-related. At this stage of dental education, the students were largely focused on their future practice and found it easier to connect to an imagined future than a past experience. In terms of student abilities to reflect, the majority were skilled at simple reflection, based on these essays since only 18% were non-reflective and 15% showed strong critical reflection skills. The open and respectful environment of the salons enabled discussion and promoted reflection. These results suggest that more opportunities for collegial conversations and instruction in reflective practice earlier in the dental curriculum may be beneficial. PMID:27037455

  1. FORMATION OF CHROMATE CONVERSION COATINGS ON ALUMINUM AND ITS ALLOYS: AN IN SITU XANES STUDY.

    SciTech Connect

    SASAKI,K.; ISAACS,H.S.; JAFFCOATE,C.S.; BUCHHAIT,R.; LEGAT,V.; LEE,H.; SRINIVASAMURTHI,V.

    2001-09-02

    We used in situ X-ray adsorption near-edge structure (XANES) to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys (AA 1100, AA2024, and AA7075), and a series of binary Al-Cu alloys. The method employed a new electrochemical cell that can determine the ratio of hexavalent chromium (Cr(VI)) to total chromium (Cr(total)) speciation in conversion coatings as a function of exposure time to a chromate solution. The spectra showed that the initial Cr(VI)/Cr(total) ratios are greater than later ones for pure Al and AA1100, but not for AA2024 and AA7075. Measurements with Al-Cu alloys demonstrated that the difference observed in AA2024 and AA7075 may not be due to Cu alloying. The proportion of Cr(VI) in the coatings becomes approximately constant after 180 s of exposure for all the specimens examined even though the coatings continue to grow.

  2. Handheld access to radiology teaching files: an automated system for format conversion and content creation

    NASA Astrophysics Data System (ADS)

    Raman, Raghav; Raman, Lalithakala; Raman, Bhargav; Gold, Garry; Beaulieu, Christopher F.

    2002-05-01

    Current handheld Personal Digital Assistants (PDAs) can be used to view radiology teaching files. We have developed a toolkit that allows rapid creation of radiology teaching files in handheld formats from existing repositories. Our toolkit incorporated a desktop converter, a web conversion server and an application programming interface (API). Our API was integrated with an existing pilot teaching file database. We evaluated our system by obtaining test DICOM and JPEG images from our PACS system, our pilot database and from personal collections and converting them on a Windows workstation (Microsoft, Redmond, CA) and on other platforms using the web server. Our toolkit anonymized, annotated and categorized images using DICOM header information and data entered by the authors. Image processing was automatically customized for the target handheld device. We used freeware handheld image viewers as well as our custom applications that allowed window/level manipulation and viewing of additional textual information. Our toolkit provides desktop and web access to image conversion tools to produce organized handheld teaching file packages for most handheld devices and our API allows existing teaching file databases to incorporate handheld compatibility. The distribution of radiology teaching files on PDAs can increase the accessibility to radiology teaching.

  3. Performance analysis of an all-optical OFDM system in presence of non-linear phase noise.

    PubMed

    Hmood, Jassim K; Harun, Sulaiman W; Emami, Siamak D; Khodaei, Amin; Noordin, Kamarul A; Ahmad, Harith; Shalaby, Hossam M H

    2015-02-23

    The potential for higher spectral efficiency has increased the interest in all-optical orthogonal frequency division multiplexing (OFDM) systems. However, the sensitivity of all-optical OFDM to fiber non-linearity, which causes nonlinear phase noise, is still a major concern. In this paper, an analytical model for estimating the phase noise due to self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in an all-optical OFDM system is presented. The phase noise versus power, distance, and number of subcarriers is evaluated by implementing the mathematical model using Matlab. In order to verify the results, an all-optical OFDM system, that uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation, is demonstrated by numerical simulation. The system employs 29 subcarriers; each subcarrier is modulated by a 4-QAM or 16-QAM format with a symbol rate of 25 Gsymbol/s. The results indicate that the phase variance due to FWM is dominant over those induced by either SPM or XPM. It is also shown that the minimum phase noise occurs at -3 dBm and -1 dBm for 4-QAM and 16-QAM, respectively. Finally, the error vector magnitude (EVM) versus subcarrier power and symbol rate is quantified using both simulation and the analytical model. It turns out that both EVM results are in good agreement with each other. PMID:25836428

  4. All-optical 2-bit header recognition and packet switching using polarization bistable VCSELs.

    PubMed

    Hayashi, Daisuke; Nakao, Kazuya; Katayama, Takeo; Kawaguchi, Hitoshi

    2015-04-01

    We propose and evaluate an all-optical 2-bit header recognition and packet switching method using two 1.55-µm polarization bistable vertical-cavity surface-emitting lasers (VCSELs) and three optical switches. Polarization bistable VCSELs acted as flip-flop devices by using AND-gate operations of the header and set pulses, together with the reset pulses. Optical packets including 40-Gb/s non-return-to-zero pseudo-random bit-sequence payloads were successfully sent to one of four ports according to the state of two bits in the headers with a 4-bit 500-Mb/s return-to-zero format. The input pulse powers were 17.2 to 31.8 dB lower than the VCSEL output power. We also examined an extension of this method to multi-bit header recognition and packet switching. PMID:25968674

  5. An explicit study of aerosol mass conversion and its parameterization in warm rain formation of cumulus clouds

    NASA Astrophysics Data System (ADS)

    Sun, J.; Fen, J.; Ungar, R. K.

    2013-10-01

    The life time of atmospheric aerosols is highly affected by in-cloud scavenging processes. Aerosol mass conversion from aerosols embedded in cloud droplets into aerosols embedded in raindrops is a pivotal pathway for wet removal of aerosols in clouds. The aerosol mass conversion rate in the bulk microphysics parameterizations is always assumed to be linearly related to the precipitation production rate, which includes the cloud water autoconversion rate and the cloud water accretion rate. The ratio of the aerosol mass concentration conversion rate to the cloud aerosol mass concentration has typically been considered to be the same as the ratio of the precipitation production rate to the cloud droplet mass concentration. However, the mass of an aerosol embedded in a cloud droplet is not linearly proportional to the mass of the cloud droplet. A simple linear relationship cannot be drawn between the precipitation production rate and the aerosol mass concentration conversion rate. In this paper, we studied the evolution of aerosol mass concentration conversion rates in a warm rain formation process with a 1.5-dimensional non-hydrostatic convective cloud and aerosol interaction model in the bin microphysics. We found that the ratio of the aerosol mass conversion rate to the cloud aerosol mass concentration can be statistically expressed by the ratio of the precipitation production rate to the cloud droplet mass concentration with an exponential function. We further gave some regression equations to determine aerosol conversions in the warm rain formation under different threshold radii of raindrops and different aerosol size distributions.

  6. A program for the conversion of The National Map data from proprietary format to resource description framework (RDF)

    USGS Publications Warehouse

    Bulen, Andrew; Carter, Jonathan J.; Varanka, Dalia E.

    2011-01-01

    To expand data functionality and capabilities for users of The National Map of the U.S. Geological Survey, data sets for six watersheds and three urban areas were converted from the Best Practices vector data model formats to Semantic Web data formats. This report describes and documents the conver-sion process. The report begins with an introduction to basic Semantic Web standards and the background of The National Map. Data were converted from a proprietary format to Geog-raphy Markup Language to capture the geometric footprint of topographic data features. Configuration files were designed to eliminate redundancy and make the conversion more efficient. A SPARQL endpoint was established for data validation and queries. The report concludes by describing the results of the conversion.

  7. A novel 40-Gb/s all-optical inverted wavelength converter based on a modified terahertz optical asymmetric demultiplexer

    NASA Astrophysics Data System (ADS)

    Huang, Xuetian; Ye, Peida; Zhang, Min; Wang, Ling

    2004-12-01

    A novel scheme for all-optical inverted wavelength conversion with 40-Gb/s pseudorandom bit sequences (PRBSs) based on a modified terahertz optical asymmetric demultiplexer (TOAD) is proposed. The performance of the proposed wavelength converter is analyzed in term of extinction ratio (ER) through numerical simulations. For a typical ER of 10 dB, some key characteristic parameters of the semiconductor optical amplifier (SOA) are designed. With the properly designed parameters, a high quality eye diagram is achievable, indicating that the amplitude fluctuation of the output signal is effectively reduced.

  8. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses.

    PubMed

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-01-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals. PMID:26323238

  9. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses

    PubMed Central

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-01-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals. PMID:26323238

  10. Transmission and full-band coherent detection of polarization-multiplexed all-optical Nyquist signals generated by Sinc-shaped Nyquist pulses

    NASA Astrophysics Data System (ADS)

    Zhang, Junwen; Yu, Jianjun; Chi, Nan

    2015-09-01

    All optical method is considered as a promising technique for high symbol rate Nyquist signal generation, which has attracted a lot of research interests for high spectral-efficiency and high-capacity optical communication system. In this paper, we extend our previous work and report the fully experimental demonstration of polarization-division multiplexed (PDM) all-optical Nyquist signal generation based on Sinc-shaped Nyquist pulse with advanced modulation formats, fiber-transmission and single-receiver full-band coherent detection. Using this scheme, we have successfully demonstrated the generation, fiber transmission and single-receiver full-band coherent detection of all-optical Nyquist PDM-QPSK and PDM-16QAM signals up to 125-GBaud. 1-Tb/s single-carrier PDM-16QAM signal generation and full-band coherent detection is realized, which shows the advantage and feasibility of the single-carrier all-optical Nyquist signals.

  11. All-optical clock recovery for 40Gbs using an amplified feedback DFB laser

    NASA Astrophysics Data System (ADS)

    Sun, Yu; Pan, J. Q.; Zhao, L. J.; Chen, W. X.; Wang, W.; Wang, L.; Zhao, X. F.; Lou, C. Y.

    2009-11-01

    All-optical clock recovery is a key technology in all-optical 3R signal regeneration (Re-amplification, Retiming, and Reshaping) process. In this paper, a monolithic integrated three-section amplified feedback semiconductor laser (AFL) is demonstrated as an all optical clock regenerator. We fabricated a three-section AFL using quantum well intermixing process without regrowth instead of butt-joint process. The tunable characteristics of three-section AFL were investigated, and all optical clock recovery for 40Gb/s return to zero (RZ) 231-1 pseudorandom binary sequence (PRBS) is demonstrated experimentally using AFL with time jitter about 689.2fs.

  12. All-optical switching of magnetoresistive devices using telecom-band femtosecond laser

    SciTech Connect

    He, Li; Chen, Jun-Yang; Wang, Jian-Ping E-mail: moli@umn.edu; Li, Mo E-mail: moli@umn.edu

    2015-09-07

    Ultrafast all-optical switching of the magnetization of various magnetic systems is an intriguing phenomenon that can have tremendous impact on information storage and processing. Here, we demonstrate all-optical switching of GdFeCo alloy films using a telecom-band femtosecond fiber laser. We further fabricate Hall cross devices and electrically readout all-optical switching by measuring anomalous Hall voltage changes. The use of a telecom laser and the demonstrated all-optical switching of magnetoresistive devices represent the first step toward integration of opto-magnetic devices with mainstream photonic devices to enable novel optical and spintronic functionalities.

  13. OptoDyCE: Automated system for high-throughput all-optical dynamic cardiac electrophysiology

    NASA Astrophysics Data System (ADS)

    Klimas, Aleksandra; Yu, Jinzhu; Ambrosi, Christina M.; Williams, John C.; Bien, Harold; Entcheva, Emilia

    2016-02-01

    In the last two decades, <30% of drugs withdrawals from the market were due to cardiac toxicity, where unintended interactions with ion channels disrupt the heart's normal electrical function. Consequently, all new drugs must undergo preclinical testing for cardiac liability, adding to an already expensive and lengthy process. Recognition that proarrhythmic effects often result from drug action on multiple ion channels demonstrates a need for integrative and comprehensive measurements. Additionally, patient-specific therapies relying on emerging technologies employing stem-cell derived cardiomyocytes (e.g. induced pluripotent stem-cell-derived cardiomyocytes, iPSC-CMs) require better screening methods to become practical. However, a high-throughput, cost-effective approach for cellular cardiac electrophysiology has not been feasible. Optical techniques for manipulation and recording provide a contactless means of dynamic, high-throughput testing of cells and tissues. Here, we consider the requirements for all-optical electrophysiology for drug testing, and we implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We demonstrate the high-throughput capabilities using multicellular samples in 96-well format by combining optogenetic actuation with simultaneous fast high-resolution optical sensing of voltage or intracellular calcium. The system can also be implemented using iPSC-CMs and other cell-types by delivery of optogenetic drivers, or through the modular use of dedicated light-sensitive somatic cells in conjunction with non-modified cells. OptoDyCE provides a truly modular and dynamic screening system, capable of fully-automated acquisition of high-content information integral for improved discovery and development of new drugs and biologics, as well as providing a means of better understanding of electrical disturbances in the heart.

  14. Mitigation of phase noise in all-optical OFDM systems based on minimizing interaction time between subcarriers

    NASA Astrophysics Data System (ADS)

    Hmood, Jassim K.; Noordin, Kamarul A.; Harun, Sulaiman W.; Shalaby, Hossam M. H.

    2015-11-01

    A new approach to mitigate the phase noise in all-optical OFDM systems is analytically modeled and numerically demonstrated. The interaction time between subcarriers is minimized by shaping the envelopes of QAM subcarriers and making a delay time between even and odd subcarriers. Return-to-zero (RZ) coding is adopted for shaping the envelopes of subcarriers. In addition, the subcarriers are alternately delayed (AD) by optical time delayers. The performance of an all-optical OFDM system, that implements the proposed technique, is analyzed and simulated. This system has 29 subcarriers with symbol rate of 25 Gsymbol/s and is composed of coupler-based inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT) schemes. Each subcarrier is modulated with QAM format before shaping with RZ coding. Due to RZ being more affected by dispersion; a full periodic dispersion map is adopted to keep the total accumulated dispersion low. The results reveal that the nonlinear phase noise (NPN) due to fiber nonlinearity is significantly mitigated when the time delay between the odd and even subcarriers is equal to half the symbol period. The total phase noise variance is reduced from 9.3×10-3 to 6.1×10-3 rad2 when employing AD RZ-QAM for a transmission distance of 550 km. Furthermore, both the transmission distance and optical signal to noise ratio (OSNR) are improved when compared to all-optical OFDM systems that adopt traditional QAM modulation formats.

  15. Does the CO-to-H2 conversion factor depend on the star formation rate?

    NASA Astrophysics Data System (ADS)

    Clark, Paul C.; Glover, Simon C. O.

    2015-09-01

    We present a series of numerical simulations that explore how the `X-factor', XCO - the conversion factor between the observed integrated CO emission and the column density of molecular hydrogen - varies with the environmental conditions in which a molecular cloud is placed. Our investigation is centred around two environmental conditions in particular: the cosmic ray ionization rate (CRIR) and the strength of the interstellar radiation field (ISRF). Since both these properties of the interstellar medium (ISM) have their origins in massive stars, we make the assumption in this paper that both the strength of the ISRF and the CRIR scale linearly with the local star formation rate (SFR). The cloud modelling in this study first involves running numerical simulations that capture the cloud dynamics, as well as the time-dependent chemistry, and ISM heating and cooling. These simulations are then post-processed with a line radiative transfer code to create synthetic 12CO (1-0) emission maps from which XCO can be calculated. We find that for 104 M⊙ virialized clouds with mean density 100 cm- 3, XCO is only weakly dependent on the local SFR, varying by a factor of a few over 2 orders of magnitude in SFR. In contrast, we find that for similar clouds but with masses of 105 M⊙, the X-factor will vary by an order of magnitude over the same range in SFR, implying that extragalactic star formation laws should be viewed with caution. However, for denser (104 cm- 3), supervirial clouds such as those found at the centre of the Milky Way, the X-factor is once again independent of the local SFR.

  16. Two bit all-optical analog-to-digital converter based on nonlinear Kerr effect in 2D photonic crystals

    NASA Astrophysics Data System (ADS)

    Youssefi, Bahar; Moravvej-Farshi, Mohammad Kazem; Granpayeh, Nosrat

    2012-06-01

    We have demonstrated the performance of a novel design for a single wavelength 2-bit all-optical analog-to-digital converter (ADC). This converter consists of two high efficient channel drop filters with a coupled cavity-based wavelength selective reflector in a 2D photonic crystal with total length of 15.87 μm. The A/D conversion is achieved by using nonlinear Kerr effect in the cavities. The output ports switch to state '1' at different input power levels to generate unique states preferred for an ADC. This conversion is simulated by the finite difference time domain (FDTD) method for 5 different power levels. The proposed structure can function as a two-bit ADC with a 60 mW/μm input pulse and its maximum sampling rate is found to be ~ 45 GS/s.

  17. Demonstration and characterisation of a non-inverting all-optical read/write regenerative memory

    NASA Astrophysics Data System (ADS)

    Johnson, N. C.; Harrison, J. A.; Blow, K. J.

    2008-09-01

    An all-optical regenerative memory device using a single loop mirror and a semiconductor optical amplifier is experimentally demonstrated. This configuration has potential for a low power all-optical stable memory device with non-inverting characteristics where packets are stored by continuously injecting the regenerated data back into the loop.

  18. Conversion of the Aerodynamic Preliminary Analysis System (APAS) to an IBM PC Compatible Format

    NASA Technical Reports Server (NTRS)

    Kruep, John M.

    1995-01-01

    The conversion of the Aerodynamic Preliminary Analysis System (APAS) software from a Silicon Graphics UNIX-based platform to a DOS-based IBM PC compatible is discussed. Relevant background information is given, followed by a discussion of the steps taken to accomplish the conversion and a discussion of the type of problems encountered during the conversion. A brief comparison of aerodynamic data obtained using APAS with data from another source is also made.

  19. Formation of beta-methylmalate and its conversion to citramalate in Rhodospirillum rubrum.

    PubMed

    Osumi, T; Ebisuno, T; Nakano, H; Katsuki, H

    1975-10-01

    Using a cell-free extract of Rhodospirillum rubrum, studies were made of the condensation reaction between propionyl-CoA and glyoxylate. When [14C]propionate was incubated with the extract in the presence of glyoxylate, ATP, CoA, Mg2+, and Mn2+, radioactivity was incorporated into several compounds. Two of the main products were characterized as citramalate (CMA) and erythro-beta-methylmalate (erythro-MMA) on the basis of their behavior compared with authentic samples of CMA and erythro-MMA in the following three analyses: (i) paper chromatography using two solvent systems, (ii) radio-gas chromatography on their methyl esters, and (iii) chemical conversion to readily crystallizable derivatives, that is, citramalyl chloralide for CMA, and thymine for MMA. The CMA was thought to be of L(+)-form based on the results of optical resolution with brucine and also its susceptibility to L(+)-citramalate lyase of Clostridium tetanomorphum. When the reaction was carried out with lower concentrations of the enzyme, only MMA was accumulated. However, when the reaction was allowed to proceed further after addition of higher concentrations of the enzyme and of excess semicarbazide to prevent further condensation, the amount of accumulated MMA was decreased and CMA was formed instead. Furthermore, the time course of MMA and CMA formation exhibited a pattern typical of a precursor-product relationship. From these results, it was concluded that MMA was formed by alpha-condensation between propionyl-CoA and glyoxylate, and that CMA was derived from MMA, possibly from its CoA derivative. PMID:814116

  20. PAPR Reduction in All-optical OFDM Systems Based on Phase Pre-emphasis

    NASA Astrophysics Data System (ADS)

    He, Zhou; Li, Wei; Tao, Zhiyong; Shao, Ji ng; Liang, Xiaojun; Deng, Zhuanhua; Huang, Dexiu

    2011-02-01

    This paper investigates the peak-to-average power ratio (PAPR) theory in all-optical orthogonal frequency division multiplexing (OFDM) optical fibre communication systems. We find out that phase pre-emphasis could effectively reduce PAPR in all-optical OFDM communication systems which employ intensity modulation-direct detection (IM-DD) method. An equation is developed and proposed to calculate suitable phasing values for pre-emphasis. Furthermore, we find out that phase pre-emphasis cannot reduce PAPR effectively in all-optical OFDM systems that employ Phase Shift Keying (PSK) or Quadracture Amplitude Modulation (QAM) method.

  1. Fabrication and experimental demonstration of the first 160 Gb/s hybrid silicon-on-insulator integrated all-optical wavelength converter.

    PubMed

    Stamatiadis, C; Stampoulidis, L; Kalavrouziotis, D; Lazarou, I; Vyrsokinos, K; Zimmermann, L; Voigt, K; Preve, G B; Moerl, L; Kreissl, J; Avramopoulos, H

    2012-02-13

    We present a hybrid integrated photonic circuit on a silicon-on-insulator substrate that performs ultra high-speed all-optical wavelength conversion. The chip incorporates a 1.25 mm non-linear SOA mounted on the SOI board using gold-tin bumps as small as 14 μm. Τhe device performs chirp filtering and signal polarity inversion with two multi-mode interference (MMI) - based cascaded delay interferometers (DIs) monolithically integrated on the same SOI substrate. Full free spectral range (FSR) tuning of the DIs is accomplished by two independently tuneable on-chip thermal heaters. We demonstrate 160Gb/s all-optical wavelength conversion with power penalties of less than 4.6dB. PMID:22418139

  2. 15 CFR 995.26 - Conversion of NOAA ENC ® files to other formats.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Foreign Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE QUALITY... data files without degradation to positional accuracy or informational content. (2) Software... software. (3) Error reporting. Any errors detected during the conversion process shall be logged...

  3. 15 CFR 995.26 - Conversion of NOAA ENC ® files to other formats.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Foreign Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE QUALITY... data files without degradation to positional accuracy or informational content. (2) Software... software. (3) Error reporting. Any errors detected during the conversion process shall be logged...

  4. 15 CFR 995.26 - Conversion of NOAA ENC ® files to other formats.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Foreign Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE QUALITY... data files without degradation to positional accuracy or informational content. (2) Software... software. (3) Error reporting. Any errors detected during the conversion process shall be logged...

  5. 15 CFR 995.26 - Conversion of NOAA ENC ® files to other formats.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Foreign Trade (Continued) NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE QUALITY... data files without degradation to positional accuracy or informational content. (2) Software... software. (3) Error reporting. Any errors detected during the conversion process shall be logged...

  6. High speed all-optical encryption and decryption using quantum dot semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2013-11-01

    A scheme to realize high speed all-optical encryption and decryption using key-stream generators and an XOR gate based on quantum dot semiconductor optical amplifiers (QD-SOAs) was studied. The key used for encryption and decryption is a high speed all-optical pseudorandom bit sequence (PRBS) which is generated by a linear feedback shift register (LFSR) composed of QD-SOA-based logic XOR and AND gates. Two other kinds of more secure key-stream generators, i.e. cascaded design and parallel design, were also designed and investigated. Nonlinear dynamics including carrier heating and spectral hole-burning in the QD-SOA are taken into account together with the rate equations in order to realize all-optical logic operations. Results show that this scheme can realize all-optical encryption and decryption by using key-stream generators at high speed (~250 Gb/s).

  7. Polarization-based all-optical logic operations in volume holographic photopolymer

    NASA Astrophysics Data System (ADS)

    Li, Chengmingyue; Cao, Liangcai; Li, Jingming; Wang, Zheng; Jin, Guofan

    2014-11-01

    Polarization-based all-optical logic operations were realized with dual-channel polarization holographic recording system. The polarization property of 9, 10-phenanthrenequinone-doped poly-methyl methacrylate (PQ/PMMA) photopolymer is investigated experimentally. To accurately represent the optical operations, the diffraction efficiency of parallel and orthogonal polarization recording in PQ/PMMA with the thickness of 1 mm are characterized for holographic recording and reconstruction process. A dual-channel polarization holographic recording system is set up for simultaneously recording two input pages. By changing the polarization state of the diffraction beam, all-optical logic OR and NAND operations are realized in the volume holograms. The polarization-based all-optical logic operations in the volume holographic photopolymer may pave a way for practical all-optical logic devices with high speed and large information capacity.

  8. Integrated all-optical logic discriminators based on plasmonic bandgap engineering

    PubMed Central

    Lu, Cuicui; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

    2013-01-01

    Optical computing uses photons as information carriers, opening up the possibility for ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic devices are indispensible core components of optical computing systems. However, up to now, little experimental progress has been made in nanoscale all-optical logic discriminators, which have the function of discriminating and encoding incident light signals according to wavelength. Here, we report a strategy to realize a nanoscale all-optical logic discriminator based on plasmonic bandgap engineering in a planar plasmonic microstructure. Light signals falling within different operating wavelength ranges are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. Also the SPP light source is integrated with the logic device while retaining its ultracompact size. This opens up a way to construct on-chip all-optical information processors and artificial intelligence systems. PMID:24071647

  9. All-Optical Terahertz Optical Asymmetric Demultiplexer (toad) Based Binary Comparator:. a Proposal

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    Comparator determines whether a number is greater than, equals to or less than another number. It plays a significant role in fast central processing unit in all-optical scheme. In all-optical scheme here 1-bit binary comparator is proposed and described by Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch. Simulation result by Mathcad-7 is also given. Cascading technique of building up the n-bit binary comparator with this 1-bit comparator block is also proposed here.

  10. All-optical polarization control and noise cleaning based on a nonlinear lossless polarizer

    NASA Astrophysics Data System (ADS)

    Barozzi, Matteo; Vannucci, Armando; Picchi, Giorgio

    2015-01-01

    We propose an all-optical fiber-based device able to accomplish both polarization control and OSNR enhancement of an amplitude modulated optical signal, affected by unpolarized additive white Gaussian noise, at the same time. The proposed noise cleaning device is made of a nonlinear lossless polarizer (NLP), that performs polarization control, followed by an ideal polarizing filter that removes the orthogonally polarized half of additive noise. The NLP transforms every input signal polarization into a unique, well defined output polarization (without any loss of signal energy) and its task is to impose a signal polarization aligned with the transparent eigenstate of the polarizing filter. In order to effectively control the polarization of the modulated signal, we show that two different NLP configurations (with counter- or co-propagating pump laser) are needed, as a function of the signal polarization coherence time. The NLP is designed so that polarization attraction is effective only on the "noiseless" (i.e., information-bearing) component of the signal and not on noise, that remains unpolarized at the NLP output. Hence, the proposed device is able to discriminate signal power (that is preserved) from in-band noise power (that is partly suppressed). Since signal repolarization is detrimental if applied to polarization-multiplexed formats, the noise cleaner application is limited here to "legacy" links, with 10 Gb/s OOK modulation, still representing the most common format in deployed networks. By employing the appropriate NLP configurations, we obtain an OSNR gain close to 3dB. Furthermore, we show how the achievable OSNR gain can be estimated theoretically.

  11. All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection

    NASA Astrophysics Data System (ADS)

    Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

    2006-05-01

    Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8dB and reduces its bit error rate to 10-12 at -18dBm.

  12. GROWTH LAWS FOR THE FORMATION OF SECONDARY AMBIENT AEROSOLS: IMPLICATIONS FOR CHEMICAL CONVERSION MECHANISMS

    EPA Science Inventory

    The evolution of aerosol size distributions growing by gas-to-particle conversion has been observed recently in field and laboratory studies. A technique for extracting particle diameter growth rates from such data is presented. The functional dependence of these growth rates on ...

  13. Citizen Participation in Policy Formation: A Review of Governor Roberts' Conversation with Oregon.

    ERIC Educational Resources Information Center

    Weeks, Edward C.; And Others

    This document presents the results of a survey of Oregon voters, polling those who did and those who did not participate in a series of meetings using the state's interactive telecommunications network, Ed-Net. The meetings were part of a project in deliberative democracy called a Conversation with Oregon, launched by Governor Barbara Roberts to…

  14. 15 CFR 995.26 - Conversion of NOAA ENC ® files to other formats.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Conversion of NOAA ENC ® files to... ASSURANCE AND CERTIFICATION REQUIREMENTS FOR NOAA HYDROGRAPHIC PRODUCTS AND SERVICES CERTIFICATION REQUIREMENTS FOR DISTRIBUTORS OF NOAA HYDROGRAPHIC PRODUCTS Requirements for Certified Distributors and...

  15. Documenting the conversion from traditional to Studio Physics formats at the Colorado School of Mines: Process and early results

    NASA Astrophysics Data System (ADS)

    Kohl, Patrick B.; Kuo, H. Vincent; Ruskell, Todd G.

    2008-10-01

    The Colorado School of Mines (CSM) has taught its first-semester introductory physics course using a hybrid lecture/Studio Physics format for several years. Over the past year we have converted the second semester of our calculus-based introductory physics course (Physics II) to a Studio Physics format, starting from a traditional lecture-based format. In this paper, we document the early stages of this conversion in order to better understand which features succeed and which do not, and in order to develop a model for switching to Studio that keeps the time and resource investment manageable. We describe the recent history of the Physics II course and of Studio at Mines, discuss the PER-based improvements that we are implementing, and characterize our progress via several metrics, including pre/post Conceptual Survey of Electricity and Magnetism (CSEM) scores, Colorado Learning About Science Survey scores (CLASS), solicited student comments, failure rates, and exam scores.

  16. Conversion of quiescent niche cells to somatic stem cells causes ectopic niche formation in the Drosophila testis

    PubMed Central

    Hétié, Phylis; de Cuevas, Margaret; Matunis, Erika

    2014-01-01

    Summary Adult stem cells reside in specialized regulatory microenvironments, or niches, where local signals ensure stem cell maintenance. The Drosophila testis contains a well-characterized niche wherein signals from post-mitotic hub cells promote maintenance of adjacent germline stem cells and somatic cyst stem cells (CySCs). Hub cells were considered to be terminally differentiated; here we show that they can give rise to CySCs. Genetic ablation of CySCs triggers hub cells to transiently exit quiescence, delaminate from the hub, and convert into functional CySCs. Ectopic Cyclin D-Cdk4 expression in hub cells is also sufficient to trigger their conversion into CySCs. In both cases, this conversion causes the formation of multiple ectopic niches over time. Therefore, our work provides a model for understanding how oncogenic mutations in quiescent niche cells could promote loss of quiescence, changes in cell fate, and aberrant niche expansion more generally. PMID:24746819

  17. Study on all-optical switching characteristics of ethyl orange-doped polymer film

    NASA Astrophysics Data System (ADS)

    Xu, Tang; Zhang, Chunping; Lin, Yu; Qi, Shengwen

    2008-10-01

    The all-optical switching polymer thin films with azobenzene dye ethyl orange as the guest material and polyvinyl alcohol (PVA) as the host material were prepared by adulteration and spin-coating methods. The all-optical switching characteristics of the samples were measured at different intensities and modulation frequencies of the pump beam (532 nm, CW); the influence of doping concentration on the all-optical switching effect of the films was studied. It is shown that, under room temperature conditions and with a low pump power of 6 mW, the all-optical switch has a response time of about 2 ms and a modulation depth of 45%, and the maximal modulation depth reaches 90%. In addition, it is found that samples with higher doping concentration show a stronger all-optical switching effect but a larger background signal, and good switching performance is obtained by choosing the doping concentrations from 0.8% to 2% of the sample.

  18. All-optical universal logic gates on nonlinear multimode interference coupler using tunable input intensity

    NASA Astrophysics Data System (ADS)

    Tajaldini, Mehdi; Jafri, Mohd Zubir Mat

    2015-04-01

    The theory of Nonlinear Modal Propagation Analysis Method (NMPA) have shown significant features of nonlinear multimode interference (MMI) coupler with compact dimension and when launched near the threshold of nonlinearity. Moreover, NMPA have the potential to allow studying the nonlinear MMI based the modal interference to explorer the phenomenon that what happen due to the natural of multimode region. Proposal of all-optical switch based NMPA has approved its capability to achieving the all-optical gates. All-optical gates have attracted increasing attention due to their practical utility in all-optical signal processing networks and systems. Nonlinear multimode interference devices could apply as universal all-optical gates due to significant features that NMPA introduce them. In this Paper, we present a novel Ultra-compact MMI coupler based on NMPA method in low intensity compared to last reports either as a novel design method and potential application for optical NAND, NOR as universal gates on single structure for Boolean logic signal processing devices and optimize their application via studding the contrast ratio between ON and OFF as a function of output width. We have applied NMPA for several applications so that the miniaturization in low nonlinear intensities is their main purpose.

  19. Conversion of Input Data between KENO and MCNP File Formats for Computer Criticality Assessments

    SciTech Connect

    Schwarz, Randolph A.; Carter, Leland L.; Schwarz Alysia L.

    2006-11-30

    KENO is a Monte Carlo criticality code that is maintained by Oak Ridge National Laboratory (ORNL). KENO is included in the SCALE (Standardized Computer Analysis for Licensing Evaluation) package. KENO is often used because it was specifically designed for criticality calculations. Because KENO has convenient geometry input, including the treatment of lattice arrays of materials, it is frequently used for production calculations. Monte Carlo N-Particle (MCNP) is a Monte Carlo transport code maintained by Los Alamos National Laboratory (LANL). MCNP has a powerful 3D geometry package and an extensive cross section database. It is a general-purpose code and may be used for calculations involving shielding or medical facilities, for example, but can also be used for criticality calculations. MCNP is becoming increasingly more popular for performing production criticality calculations. Both codes have their own specific advantages. After a criticality calculation has been performed with one of the codes, it is often desirable (or may be a safety requirement) to repeat the calculation with the other code to compare the important parameters using a different geometry treatment and cross section database. This manual conversion of input files between the two codes is labor intensive. The industry needs the capability of converting geometry models between MCNP and KENO without a large investment in manpower. The proposed conversion package will aid the user in converting between the codes. It is not intended to be used as a “black box”. The resulting input file will need to be carefully inspected by criticality safety personnel to verify the intent of the calculation is preserved in the conversion. The purpose of this package is to help the criticality specialist in the conversion process by converting the geometry, materials, and pertinent data cards.

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

    PubMed

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

    2011-11-21

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

  1. Tunable optoelectronic oscillator incorporating an all-optical microwave photonic filter

    NASA Astrophysics Data System (ADS)

    Li, Cheng-Xin; Chen, Fu-Shen; Zhang, Jia-Hong

    2015-01-01

    A tunable optoelectronic oscillator (OEO), which employs an all-optical microwave photonic filter (MPF) consisting of two laser sources (LD1 and LD2), an optical coupler (OC, 50:50), a Mach-Zehnder modulator (MZM), and a chirped fiber Bragg grating, is proposed. Because the central frequency of the all-optical MPF can be shifted by changing the wavelength spacing between the two laser sources, the frequency tunability of the OEO can be realized by incorporating such an all-optical MPF into an optical domain dual-loop OEO without any electronic microwave filters. A detailed theoretical analysis is presented and the results are confirmed by an experiment. A microwave signal with a frequency-tuning range from 4.057 to 8.595 GHz is generated. The phase noise, the long-term stability, and the side-mode suppression performance of the generated microwave signal are also investigated.

  2. Numerical investigation of an all-optical switch in a graded nonlinear plasmonic grating.

    PubMed

    Wang, Guoxi; Lu, Hua; Liu, Xueming; Gong, Yongkang

    2012-11-01

    We have proposed and numerically investigated an all-optical switch based on a metal-insulator-metal waveguide with graded nonlinear plasmonic gratings. The influences of grating depth and refractive index of a Kerr nonlinear medium on the transmission of the switch are exactly analyzed by utilizing transmission line theory. The finite-difference time-domain simulation results show that the highly compact structure possesses excellent switch function by tuning the incident electric field intensity. In addition, the simulation results show that this all-optical switch has an ultrawide operating frequency regime and femtosecond-scale response time (~130 fs). Such a switch can find potential applications for all-optical signal processing and optical communication. PMID:23080383

  3. All-Optical Helicity Dependent Spin Switching in a Many-Spin System

    NASA Astrophysics Data System (ADS)

    Latta, Tanner; Zhang, G. P.

    All-optical helicity dependent magnetic switching (AOS) is achieved through using an ultrafast laser pulse to manipulate and switch the spin of an electron from one direction to another. This process happens in a short amount of femtoseconds after the laser pulse is introduced. All-optical helicity dependent magnetic switching (AOS) does not fall to the assistance of any external magnetic field. Linearly polarized light, as well as right and left circularly polarized light are used to manipulate the spin of the electrons. Ferrimagnetic, rather than ferromagnetic, materials are more suitable to create conditions in which AOS are viable due to the orientation of the spins within this material. In the following study we show and conclude that AOS is possible with the use of left and right circularly polarized laser pulses. All-optical helicity dependent magnetic switching has many applications in magnetic recording technology or magnetic memory devices. DE-FG02-06ER46304.

  4. Novel real-time monitoring technique of the all-optical poling process

    NASA Astrophysics Data System (ADS)

    Apostoluk, Aleksandra; Chapron, David; Sahraoui, Bouchta; Gadret, Gregory; Fiorini-Debuisschert, Celine; Raimond, Paul; Nunzi, Jean-Michel

    2002-03-01

    All-optical poling technique permits purely optical orientation of molecules. The experiment consists of two steps: the writing (so-called seeding) period and the readout one. In the seeding phase two beams, the fundamental one ((omega) ) and its second harmonic (SH, 2(omega) ) illuminate the sample and print in the medium the second order (chi) (2) susceptibility grating with a periodicity satisfying the condition of phase matching for SH generation. In the readout period only the fundamental beam irradiates the sample, and the second harmonic generation is observed at the sample output. Efficient all-optical poling requires optimisation of the seeding beam intensities and their relative phase difference. We propose a novel technique for non-perturbative monitoring of the all-optical poling process and the easy method of orienting molecules without any necessity of taking into account the phase difference between seeding beams.

  5. All-Optical Switching in Bacteriorhodopsin Based on Excited-State Absorption

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev

    2008-03-01

    Switching light with light is of tremendous importance for both fundamental and applied science. The advent of nano-bio-photonics has led to the design, synthesis and characterization of novel biomolecules that exhibit an efficient nonlinear optical response, which can be utilized for designing all-optical biomolecular switches. Bacteriorhodopsin (bR) protein found in the purple membrane of Halobacterium halobium has been the focus of intense research due to its unique properties that can also be tailored by physical, chemical and genetic engineering techniques to suit desired applications. The talk would focus on our recent results on all-optical switching in bR and its mutants, based on excited-state absorption, using the pump-probe technique. We would discuss the all-optical control of various features of the switching characteristics such as switching contrast, switching time, switching pump intensity, switched probe profile and phase, and relative phase-shift. Optimized conditions for all-optical switching that include optimized values of the small-signal absorption coefficient (for cw case), the pump pulse width and concentration for maximum switching contrast (for pulsed case), would be presented. We would discuss the desired optimal spectral and kinetic properties for device applications. We would also discuss the application of all-optical switching to design low power all-optical computing devices, such as, spatial light modulators, logic gates and multiplexers and compare their performance with other natural photoreceptors such as pharaonis phoborhodopsin, proteorhodopsin, photoactive yellow protein and the blue light plant photoreceptor phototropin.

  6. Polarization-encoded all-optical quaternary universal inverter and design of multivalued flip-flop

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Roy, Jitendra Nath

    2010-03-01

    Quaternary inverters are the fundamental building blocks of multivalued flip-flops (MVFFs). A novel all-optical quaternary universal inverter circuit with the help of a semiconductor optical amplifier-assisted Sagnac switch is proposed and described. This circuit exploits the polarization properties of light. Different logical states are represented by different polarization states of light. A terahertz optical asymmetric multiplexer-based gate plays an important role here. Numerical simulation results confirming the described method are given. An all-optical circuit for a MVFF (quaternary) with the help of our proposed quaternary universal inverter is also designed, and simulation results are presented.

  7. Low-power and ultrafast all-optical tunable plasmon-induced transparency in plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Chai, Zhen; Hu, Xiaoyong; Zhu, Yu; Zhang, Fan; Yang, Hong; Gong, Qihuang

    2013-05-01

    We report an ultrafast and low-power all-optical tunable plasmon-induced transparency in a plasmonic nanostructure consisting of a gold nanowire grating embedded in a polycrystalline lithium niobate layer, realized based on strong quantum confinement enhancing nonlinearity. The all-optical tunability is realized based on the third-order nonlinear Kerr effect. A shift of 30 nm in the central wavelength of the transparency window is achieved under excitation of a pump light with an intensity as low as 7 MW/cm2. An ultrafast response time of 69 ps is reached because of ultrafast relaxation dynamics of bound electrons in polycrystalline lithium niobate.

  8. High-order all-optical differential equation solver based on microring resonators.

    PubMed

    Tan, Sisi; Xiang, Lei; Zou, Jinghui; Zhang, Qiang; Wu, Zhao; Yu, Yu; Dong, Jianji; Zhang, Xinliang

    2013-10-01

    We propose and experimentally demonstrate a feasible integrated scheme to solve all-optical differential equations using microring resonators (MRRs) that is capable of solving first- and second-order linear ordinary differential equations with different constant coefficients. Employing two cascaded MRRs with different radii, an excellent agreement between the numerical simulation and the experimental results is obtained. Due to the inherent merits of silicon-based devices for all-optical computing, such as low power consumption, small size, and high speed, this finding may motivate the development of integrated optical signal processors and further extend optical computing technologies. PMID:24081039

  9. All-optical steering of the interactions between multiple spatial solitons in isotropic polymers

    NASA Astrophysics Data System (ADS)

    Yan, Li-fen; Zhang, Dong; Jin, Qing-li; Wang, Hong-cheng; Zhang, Yao-ju

    2010-11-01

    All-optical steering of the nonlinear interactions between multiple spatial solitons can be performed in an isotropic photoisomerization polymer, by propagating an external control beam in perpendicular direction. Fusing, giving birth to another new soliton, and transferring energy can take place in the interactions of signal beams, which can be achieved by changing the incident position of the control beam, the initial relative phase and the power ratio between the signal beams and the control beam. These phenomena are physically explained, and they have significantly potential applications in optical signal readdressing, logic gating, and all-optical switching, etc.

  10. In situ conversion process systems utilizing wellbores in at least two regions of a formation

    DOEpatents

    Vinegar, Harold J.; Hsu, Chia-Fu

    2011-09-27

    A system for heating a subsurface formation is described. The system includes a plurality of elongated heaters located in a plurality of openings in the formation. At least two of the heaters are substantially parallel to each other for at least a portion of the lengths of the heaters. At least two of the heaters have first end portions in a first region of the formation and second end portions in a second region of the formation. A source of time-varying current is configured to apply time-varying current to at least two of the heaters. The first end portions of at least two heaters are configured to have substantially the same voltage applied to them. The second portions of at least two heaters are configured to have substantially the same voltage applied to them.

  11. Formation and conversion of defect centers in low water peak single mode optical fiber induced by gamma rays irradiation

    SciTech Connect

    Wen, J. X.; Luo, W. Y.; Xiao, Z. Y.; Wang, T. Y.; Chen, Z. Y.; Zeng, X. L.

    2010-02-15

    The formation and conversion processes of defect centers in low water peak single mode optical (LWPSM) fiber irradiated with gamma rays were investigated at room temperature using electron spin resonance. Germanium electron center (GEC) and self-trapped hole center (STH) occur when the fibers are irradiated with 1 and 5 kGy cumulative doses, respectively. With the increase in irradiation doses, the GEC defect centers disappear, and new defect centers such as E{sup '} centers (Si and Ge) and nonbridge oxygen hole centers (NBOHCs) generate. The generation of GEC and STH is attributed to the electron transfer, which is completely balanced. This is the main reason that radiation-induced attenuation (RIA) of the LWPSM fiber is only 10 dB/km at communication window. The new defect centers come from the conversion of GEC and STH to E{sup '} centers and NBOHC, and the conversion processes cause bond cleavage, which is the root cause that the RIA of the LWPSM fiber significantly increases up to 180 dB/km at working window. Furthermore, the concentration of new defect centers is saturated easily even by increasing cumulative doses.

  12. Formation Mechanism of the First Carbon-Carbon Bond and the First Olefin in the Methanol Conversion into Hydrocarbons.

    PubMed

    Liu, Yue; Müller, Sebastian; Berger, Daniel; Jelic, Jelena; Reuter, Karsten; Tonigold, Markus; Sanchez-Sanchez, Maricruz; Lercher, Johannes A

    2016-05-01

    The elementary reactions leading to the formation of the first carbon-carbon bond during early stages of the zeolite-catalyzed methanol conversion into hydrocarbons were identified by combining kinetics, spectroscopy, and DFT calculations. The first intermediates containing a C-C bond are acetic acid and methyl acetate, which are formed through carbonylation of methanol or dimethyl ether even in presence of water. A series of acid-catalyzed reactions including acetylation, decarboxylation, aldol condensation, and cracking convert those intermediates into a mixture of surface bounded hydrocarbons, the hydrocarbon pool, as well as into the first olefin leaving the catalyst. This carbonylation based mechanism has an energy barrier of 80 kJ mol(-1) for the formation of the first C-C bond, in line with a broad range of experiments, and significantly lower than the barriers associated with earlier proposed mechanisms. PMID:27037603

  13. Enhancement of photoinduced anisotropy and all-optical switching in Bacteriorhodopsin films

    NASA Astrophysics Data System (ADS)

    Wu, Pengfei; Rao, D. V. G. L. N.; Kimball, B. R.; Nakashima, M.; DeCristofano, B. S.

    2002-11-01

    Large enhancement of photoanisotropic effects is demonstrated in thin films of the biomaterial Bacteriorhodopsin by using two exciting beams of orthogonal polarization. The mechanism of the enhancement originates from optimization of direction-selected photoisomerization of the biomaterial controlled by the polarized exciting beams. The technique is applied for achieving an all-optical switch with the additional feature of output sign control.

  14. Polarization encoded all-optical quaternary R-S flip-flop using binary latch

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Roy, Jitendra Nath; Chakraborty, Ajoy Kumar

    2009-04-01

    The developments of different multi-valued logic (MVL) systems have received considerable interests in recent years all over the world. In electronics, efforts have already been made to incorporate multi-valued system in logic and arithmetic data processing. But, very little efforts have been given in realization of MVL with optics. In this paper we present novel designs of certain all-optical circuits that can be used for realizing multi-valued logic functions. Polarization encoded all-optical quaternary (4-valued) R-S flip-flop is proposed and described. Two key circuits (all-optical encoder/decoder and a binary latch) are designed first. They are used to realize quaternary flip-flop in all-optical domain. Here the different quaternary logical states are represented by different polarized state of light. Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch can take an important role. Computer simulation result confirming described methods and conclusion are given in this paper.

  15. Integration of photonic nanojets and semiconductor nanoparticles for enhanced all-optical switching

    PubMed Central

    Born, Brandon; Krupa, Jeffrey D. A.; Geoffroy-Gagnon, Simon; Holzman, Jonathan F.

    2015-01-01

    All-optical switching is the foundation of emerging all-optical (terabit-per-second) networks and processors. All-optical switching has attracted considerable attention, but it must ultimately support operation with femtojoule switching energies and femtosecond switching times to be effective. Here we introduce an all-optical switch architecture in the form of a dielectric sphere that focuses a high-intensity photonic nanojet into a peripheral coating of semiconductor nanoparticles. Milli-scale spheres coated with Si and SiC nanoparticles yield switching energies of 200 and 100 fJ with switching times of 10 ps and 350 fs, respectively. Micro-scale spheres coated with Si and SiC nanoparticles yield switching energies of 1 pJ and 20 fJ with switching times of 2 ps and 270 fs, respectively. We show that femtojoule switching energies are enabled by localized photoinjection from the photonic nanojets and that femtosecond switching times are enabled by localized recombination within the semiconductor nanoparticles. PMID:26314911

  16. Dual-control nonlinear-optical loop mirrors for all-optical soliton synchronous modulation

    NASA Astrophysics Data System (ADS)

    Bigo, Sébastien; Desurvire, Emmanuel; Audouin, Olivier

    1996-09-01

    A novel dual-control configuration of nonlinear loop mirrors is used for all-optical soliton synchronous regeneration. Simulations show substantial improvement in transmission in this device compared with single-control devices, owing to chirp-free modulation. The absence of chirp is confirmed experimentally through a spectral analysis of the dual-control modulator.

  17. Magnetic induction measurements using an all-optical {sup 87}Rb atomic magnetometer

    SciTech Connect

    Wickenbrock, Arne; Tricot, François; Renzoni, Ferruccio

    2013-12-09

    In this work we propose, and experimentally demonstrate, the use of a self-oscillating all-optical atomic magnetometer for magnetic induction measurements. Given the potential for miniaturization of atomic magnetometers, and their extreme sensitivity, the present work shows that atomic magnetometers may play a key role in the development of instrumentation for magnetic induction tomography.

  18. Numerical investigation of all-optical add-drop multiplexing for spectrally overlapping OFDM signals.

    PubMed

    Sygletos, S; Fabbri, S; Giacoumidis, E; Sorokina, M; Marom, D M; Stephens, M F C; Klonidis, D; Tomkos, I; Ellis, A D

    2015-03-01

    We propose a novel architecture for all-optical add-drop multiplexing of OFDM signals. Sub-channel extraction is achieved by means of waveform replication and coherent subtraction from the OFDM super-channel. Numerical simulations have been carried out to benchmark the performance of the architecture against critical design parameters. PMID:25836815

  19. Analysis of all-optically tunable functionalities in subwavelength periodic structures by the Fourier modal method

    NASA Astrophysics Data System (ADS)

    Bej, Subhajit; Tervo, Jani; Francés, Jorge; Svirko, Yuri P.; Turunen, Jari

    2016-05-01

    We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.

  20. Micro-ring resonator based all-optical reconfigurable logic operations

    NASA Astrophysics Data System (ADS)

    Rakshit, Jayanta Kumar; Roy, Jitendra Nath

    2014-06-01

    An all-optical reconfigurable logic operation essentially constitutes a key technology for performing various processing tasks with ultrafast signal-processing technologies. We present designs and simulations for highly cascadable all-optical reconfigurable logic operations using GaAs-AlGaAs micro-ring resonator based optical switches and multiplexers. The switching action of the ring resonator is achieved through variation in the refractive index of the ring resonator produced by the two-photon absorption (TPA) effect through the application of optical pump pulse. The proposed circuit can perform any of the four digital logic operations (NOT, NOR, XOR, AND) by using the appropriate optical pump signal at the selection port of the multiplexer. We have tried to exploit the advantages of micro-ring resonator based all optical switch to design an all-optical circuit. The reconfigurable nature of the circuit offers maximum flexibility for the end user since the entire application can be changed simply by adjusting the multiplexer select line signals. Numerical simulation confirming described methods is given in this paper.

  1. Routing and wavelength assignment based on normalized resource and constraints for all-optical network

    NASA Astrophysics Data System (ADS)

    Joo, Seong-Soon; Nam, Hyun-Soon; Lim, Chang-Kyu

    2003-08-01

    With the rapid growth of the Optical Internet, high capacity pipes is finally destined to support end-to-end IP on the WDM optical network. Newly launched 2D MEMS optical switching module in the market supports that expectations of upcoming a transparent optical cross-connect in the network have encouraged the field applicable research on establishing real all-optical transparent network. To open up a customer-driven bandwidth services, design of the optical transport network becomes more challenging task in terms of optimal network resource usage. This paper presents a practical approach to finding a route and wavelength assignment for wavelength routed all-optical network, which has λ-plane OXC switches and wavelength converters, and supports that optical paths are randomly set up and released by dynamic wavelength provisioning to create bandwidth between end users with timescales on the order of seconds or milliseconds. We suggest three constraints to make the RWA problem become more practical one on deployment for wavelength routed all-optical network in network view: limitation on maximum hop of a route within bearable optical network impairments, limitation on minimum hops to travel before converting a wavelength, and limitation on calculation time to find all routes for connections requested at once. We design the NRCD (Normalized Resource and Constraints for All-Optical Network RWA Design) algorithm for the Tera OXC: network resource for a route is calculated by the number of internal switching paths established in each OXC nodes on the route, and is normalized by ratio of number of paths established and number of paths equipped in a node. We show that it fits for the RWA algorithm of the wavelength routed all-optical network through real experiments on the distributed objects platform.

  2. Formative assessment and equity: An exploration of opportunities for eliciting, recognizing, and responding within science classroom conversations

    NASA Astrophysics Data System (ADS)

    Morrison, Deb

    Educational inequity can be seen in both student participation and achievement outcomes. In science education, as in many other areas of education, disparities in equity of achievement (NCES, 2011) and equity of participation in science learning environments (Brown & Ryoo, 2008; Calabrese Barton, 2003) have been well documented. Some of these studies highlight the need to understand the components of effective science classroom talk as a way to bridge everyday and scientific discourse practices, to engage students in the intellectual work of sense-making in science. The National Research Council ([NRC]; 2012) specifically named the everyday to scientific connections of science classroom discourse as a focus for work on science learning equity. Formative assessment practices in science classrooms may provide an entree for teachers to improve their connections between everyday and science classroom discourses (Black & Wiliam, 1998b). In this study I examined science classroom conversations during formative assessment discussions in 10th grade biology contexts to determine where opportunities might exist to improve science learning. I engaged a theoretical framework focused on discourse (Gee, 2012) and classroom talk (Michaels, O'Connor, & Resnick, 2008) to socially situate student-teacher interactions in a community of learners (Rogoff, 1994). I used qualitative analysis (Gee, 2011; Carspecken, 1996) to locate patterns of talk during whole class and small group discussions of two science teachers, Robyn and Lisa, as they engaged in a two-year professional development focused on formative assessment. Both teachers' classroom conversation practices showed a number of opportunities to promote equity. Robyn and Lisa used common formative assessment tools to reorganize the way that students participated in their classroom conversations, allowing students individual thinking time prior to classroom talk. While Robyn often expanded reasoning herself, Lisa tended to press

  3. Selective Conversion of 5-Hydroxymethylfuraldehyde Using Cp*Ir Catalysts in Aqueous Formate Buffer Solution.

    PubMed

    Wu, Wei-Peng; Xu, Yong-Jian; Zhu, Rui; Cui, Min-Shu; Li, Xing-Long; Deng, Jin; Fu, Yao

    2016-05-23

    The highly selective hydrogenation/hydrolytic ring-opening reaction of 5-hydroxymethylfuraldehyde (5-HMF) was catalyzed by homogeneous Cp*Ir(III) half-sandwich complexes to produce 1-hydroxy-2,5-hexanedione (HHD). Adjustment of pH was found to regulate the distribution of products and reaction selectivity, and full conversion of 5-HMF to HHD with 99 % selectivity was achieved at pH 2.5. A mechanistic study revealed that the hydrolysis/ring-opening reaction of 2,5-bis-(hydroxymethyl)furan is the important intermediate reaction step. In addition, an isolated yield of 85 % for HHD was obtained in a 10 g-scale experiment, and the reaction with fructose as the starting material also led to a 98 % GC yield (71.9 % to fructose) of HHD owing to the excellent tolerance of the catalyst under acidic conditions. PMID:27075722

  4. Phase equilibrium in the formation of silicon carbide by topochemical conversion of silicon

    NASA Astrophysics Data System (ADS)

    Kukushkin, S. A.; Osipov, A. V.

    2016-04-01

    Methods of linear algebra were used to find a basis of independent chemical reactions in the topochemical conversion of silicon into silicon carbide by the reaction with carbon monoxide. The pressure-flow phase diagram was calculated from this basis, describing the composition of the solid phase for a particular design of vacuum furnace. It was demonstrated that to grow pure silicon carbide, it is necessary to ensure the pressure of carbon monoxide less than a certain value and its flow more than a certain value, depending on the temperature of the process. The elastic fields around vacancies formed were considered for the first time in calculating the topochemical reaction. It was shown that the anisotropy of these fields in a cubic crystal increases the constant of the main reaction approximately fourfold.

  5. Rapid Conversion of Traditional Introductory Physics Sequences to an Activity-Based Format

    ERIC Educational Resources Information Center

    Yoder, Garett; Cook, Jerry

    2014-01-01

    The Department of Physics at EKU [Eastern Kentucky University] with support from the National Science Foundations Course Curriculum and Laboratory Improvement Program has successfully converted our entire introductory physics sequence, both algebra-based and calculus-based courses, to an activity-based format where laboratory activities,…

  6. Blended E-Learning Skeleton of Conversation: Improving Formative Assessment in Undergraduate Dissertation Supervision

    ERIC Educational Resources Information Center

    Heinze, Aleksej; Heinze, Beverley

    2009-01-01

    The supervision of undergraduate student dissertations is an area in need of research. Although some studies have already addressed this, these are primarily based on academic staff responses. This study contributes to knowledge by gathering the responses of students and focusing on formative electronic assessment. Data was collected using a…

  7. Ordered nano-scale domains in lithium niobate single crystals via phase-mask assisted all-optical poling

    NASA Astrophysics Data System (ADS)

    Wellington, I. T.; Valdivia, C. E.; Sono, T. J.; Sones, C. L.; Mailis, S.; Eason, R. W.

    2007-02-01

    We report the formation of directionally ordered nano-scale surface domains on the +z face of undoped congruent lithium niobate single crystals by using UV illumination through a phase mask of sub-micron periodicity with an energy fluence between ˜90 mJ/cm 2 and 150 mJ/cm 2 at λ = 266 nm. We clearly show here that the UV-induced surface ferroelectric domains only nucleate at and propagate along maxima of laser intensity. Although the domain line separation varies and is greater than 2 μm for this set of experimental conditions, this enables a degree of control over the all-optical poling process.

  8. All-optical ultrafast wavelength and mode converter based on inter-modal four-wave mixing in few-mode fibers

    NASA Astrophysics Data System (ADS)

    Weng, Yi; He, Xuan; Wang, Junyi; Pan, Zhongqi

    2015-08-01

    An ultrafast all-optical simultaneous wavelength and mode conversion scheme is purposed based on intermodal four-wave mixing (IM-FWM), with the capability of switching state of polarization (SOP) and mode degeneracy orientation (MDO) in few-mode fibers (FMF). The relation among the conversion efficiency, pump power and phase matching conditions is investigated in theory analysis and simulation. Using this scheme, cross-polarization modulation (XPolM) and cross-mode modulation (XMM) can be achieved, by in the best case up to 50% conversion efficiency. Furthermore, numerical results further indicate that the proposed configuration has the potential application for generating doughnut modes by the mixing of three characteristic spatial frequencies.

  9. Conversion of school nurse policy and procedure manual to electronic format.

    PubMed

    Randall, Joellyn; Knee, Rachel; Galemore, Cynthia

    2006-10-01

    Policy and procedure manuals are essential to establishing standards of practice and ensuring quality of care to students and families. The Olathe District Schools (Kansas) Technology Department created the Virtual File Cabinet to provide online access to employee policies, school board policies, forms, and other documents. A task force of school nurses was formed to convert the nursing department's policies, procedures, protocols, and forms from hard copy to electronic format and make them available on the district's Virtual File Cabinet. Having the policy and procedure manuals in electronic format allows for quick access and ease in updating information, thereby guaranteeing the school nurses have access to the most current information. Cost savings were realized by reducing the amount of paper and staff time needed to copy, collate, and assemble materials. PMID:17172198

  10. Formation, dynamics, and implication of solid electrolyte interphase in high voltage reversible conversion fluoride nanocomposites

    SciTech Connect

    Gmitter, Andrew J.; Badway, Fadwa; Rangan, Sylvie; Bartynski, Robert A.; Halajko, Anna; Pereira, Nathalie; Amatucci, Glenn G.

    2010-01-01

    Metal fluoride nanocomposites are uniquely suited as an alternative pathway to provide very high energy density cathodes for lithium batteries. Contrasted with modern intercalation compounds, they undergo conversion upon discharge into nanodomains of lithium fluoride and highly active metal. The nanosized metal formed during the discharge process along with the dynamic nature of the crystal structure may have considerable impact on the stability of any solid state interphase formed through reaction with the electrolyte. This is in contrast to the more macrocrystalline and stable crystal structure of traditional intercalation compounds. It has been found that the cyclic carbonates are susceptible to decomposition on the nanometal surfaces at potentials as high as 2.00 V vs. Li, and the products have been identified with Field Emission Scanning Electron Microscopy (FESEM), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and X-ray Photoelectron Spectroscopy (XPS) as lithium carbonate species. Of greater importance is the impact of these decomposition products on the reversible cycling of the metal fluoride. Through a series of potentiodynamic and galvanostatic cycling trials, a clear relationship has been developed for the bismuth fluoride nanocomposites, the decomposition of the electrolyte solvent, and the cycle life. Acyclic organic carbonate solvents have been found to have minimal interaction and exhibited better long-term cycling performance than cyclic solvents.

  11. Optical NRZ-to-RZ format conversion based on frequency chirp linearization and spectrum slicing

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Huo, Li; Chen, Xin; Jiang, Xiangyu; Lou, Caiyun

    2015-12-01

    A flexible optical NRZ-to-RZ format converter based on a time lens followed by optical filtering is proposed and demonstrated experimentally. After frequency chirp linearization, 9-tone ultra-flat optical frequency comb of 25-GHz frequency spacing within 1 dB power variation is obtained. By changing the shape of the following optical band-pass filter, 3.4-ps Nyquist-shaped RZ signal and 3.7-ps Gaussian-shaped RZ signal are both achieved. The sensitivity improvements at a bit error rate of 10-9 are 3.3 dB and 1.7 dB, respectively.

  12. All-optical signal amplifier and distributor using cavity-atom coupling systems

    NASA Astrophysics Data System (ADS)

    Duan, Yafan; Lin, Gongwei; Niu, Yueping; Gong, Shangqing

    2016-05-01

    We report an all-optical signal amplifier and a signal distributor using cavity-atom coupling systems. In this system we couple atoms with an optical cavity and realize the great enhancement of a control laser by the cavity with the help of two high coupling lasers. By this effect, we can use one weak control field to control another strong target field and the intensity changes are linear with our experimental conditions. This can be used as an all-optical signal amplifier, also known as a ‘transphasor’. In our experiment, the gain of the weak field to strong field can be as high as 60. Furthermore, we can realize the distribution of optical signals, if we coordinate multiple cavity-atom coupling systems.

  13. All-optical switching characteristics in bacteriorhodopsin and its applications in integrated optics.

    PubMed

    Huang, Yuhua; Wu, Shin-Tson; Zhao, Youyuan

    2004-03-01

    We experimentally and theoretically investigated the optical switching characteristics of bacteriorhodopsin (bR) at lambda=633 nm using the pump-probe method. A diode-pumped second harmonic YAG laser (lambda=532 nm which is located around the maximum initial Br state absorption) was used as a pumping beam and a cw He-Ne laser (lambda=633 nm which is around the peaks of K and O states) was used as a probe. Due to the nonlinear intensity induced excited state absorption of the K, L, M, N, and O states in the bR photocycle, the switching characteristics are sensitive to the intensity of the probe and pump beams. Based on this property, we have demonstrated an all-optical device functioning as 11 kinds of variable binary all-optical logic gates. PMID:19474900

  14. All-optical switching characteristics in bacteriorhodopsin and its applications in integrated optics

    NASA Astrophysics Data System (ADS)

    Huang, Yuhua; Wu, Shin-Tson; Zhao, Youyuan

    2004-03-01

    We experimentally and theoretically investigated the optical switching characteristics of bacteriorhodopsin (bR) at l=633 nm using the pump-probe method. A diode-pumped second harmonic YAG laser (l=532 nm which is located around the maximum initial Br state absorption) was used as a pumping beam and a cw He-Ne laser (l=633 nm which is around the peaks of K and O states) was used as a probe. Due to the nonlinear intensity induced excited state absorption of the K, L, M, N, and O states in the bR photocycle, the switching characteristics are sensitive to the intensity of the probe and pump beams. Based on this property, we have demonstrated an all-optical device functioning as 11 kinds of variable binary all-optical logic gates.

  15. All-optical pseudorandom binary sequence generator with TOAD-based D flip-flops

    NASA Astrophysics Data System (ADS)

    Zoiros, K. E.; Das, M. K.; Gayen, D. K.; Maity, H. K.; Chattopadhyay, T.; Roy, J. N.

    2011-09-01

    An all-optical pseudo random binary sequence (PRBS) generator is designed using serially interconnected discrete Terahertz Optical Asymmetric Demultiplexer (TOAD)-based D flip-flops in a configuration exactly like the standard electronic setup. The performance of the circuit is evaluated through numerical simulation, which confirms its feasibility in terms of the choice of the critical parameters. The proposed scheme has been theoretically demonstrated for a 3-bit and 7-bit degree PRBS but can be extended to higher order by means of additional TOAD-based D flip-flops. Thus it can constitute an efficient solution for implementing all-optically a PRBS in an affordable, controllable and realistic manner.

  16. 20Gbit/s all-optical logic OR in terahertz optical asymmetric demultiplexer (TOAD)

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Wu, Jian; Lin, Jintong

    2005-01-01

    A scheme for all-optical logic OR based on transparent teraherz optical asymmetric demultiplexer (transparent-TOAD) is proposed in this paper. In the transparent-TOAD, the SOA is biased at transparency and the gain recovery time determined by the intraband effect has the value of only a few picoseconds. Numerical analysis shows that the switching window of the transparent-TOAD is only about 0.54ps and the potential for ultrahigh speed all-optical logic processing is shown. Numerical demonstration is performed for 4-bit and 16-bit logic OR at 20Gbit/s. The results coincide with the OR truth table, showing high extinction ratio and no pattern dependency. Detailed analysis is carried out on the performance of the logic OR scheme.

  17. Ultrafast All-Optical Switching with Magnetic Resonances in Nonlinear Dielectric Nanostructures.

    PubMed

    Shcherbakov, Maxim R; Vabishchevich, Polina P; Shorokhov, Alexander S; Chong, Katie E; Choi, Duk-Yong; Staude, Isabelle; Miroshnichenko, Andrey E; Neshev, Dragomir N; Fedyanin, Andrey A; Kivshar, Yuri S

    2015-10-14

    We demonstrate experimentally ultrafast all-optical switching in subwavelength nonlinear dielectric nanostructures exhibiting localized magnetic Mie resonances. We employ amorphous silicon nanodisks to achieve strong self-modulation of femtosecond pulses with a depth of 60% at picojoule-per-disk pump energies. In the pump-probe measurements, we reveal that switching in the nanodisks can be governed by pulse-limited 65 fs-long two-photon absorption being enhanced by a factor of 80 with respect to the unstructured silicon film. We also show that undesirable free-carrier effects can be suppressed by a proper spectral positioning of the magnetic resonance, making such a structure the fastest all-optical switch operating at the nanoscale. PMID:26393983

  18. Tunable all-optical plasmonic diode based on Fano resonance in nonlinear waveguide coupled with cavities.

    PubMed

    Fan, Cairong; Shi, Fenghua; Wu, Hongxing; Chen, Yihang

    2015-06-01

    Tunable all-optical plasmonic diode is proposed based on the Fano resonance in an asymmetric and nonlinear system, comprising metal-insulator-metal waveguides coupled with nanocavities. The spatial asymmetry of the system gives rise to the nonreciprocity of the field localizations at the nonlinear gap between the coupled cavities and to the nonreciprocal nonlinear response. Nonlinear Fano resonance, originating from the interference between the discrete cavity mode and the continuum traveling mode, is observed and effectively tuned by changing the input power. By combining the unidirectional nonlinear response with the steep dispersion of the Fano asymmetric line shape, a transmission contrast ratio up to 41.46 dB can be achieved between forward and backward transmission. Our all-optical plasmonic diode with compact structure can find important applications in integrated optical nanocircuits. PMID:26030529

  19. All-optical photoacoustic microscopy based on plasmonic detection of broadband ultrasound

    NASA Astrophysics Data System (ADS)

    Wang, Tianxiong; Cao, Rui; Ning, Bo; Dixon, Adam J.; Hossack, John A.; Klibanov, Alexander L.; Zhou, Qifa; Wang, Anbo; Hu, Song

    2015-10-01

    We report on an implementation of all-optical photoacoustic microscopy (PAM), which capitalizes on the effect of surface plasmon resonance (SPR) for optical detection of ultrasound. The SPR sensor in our all-optical PAM shows, experimentally, a linear response to the acoustic pressure from 5.2 kPa to 2.1 MPa, an ultra-flat frequency response (±0.7 dB) from 680 kHz to 126 MHz, and a noise-equivalent pressure sensitivity of 3.3 kPa. With the broadband ultrasonic detection, our SPR-PAM has achieved high spatial resolution with relatively low anisotropy (i.e., 2.0 μm laterally and 8.4 μm axially). Three-dimensional high-resolution imaging of a single melanoma cell is demonstrated.

  20. All-optical background subtraction readout method for bimaterial cantilever array sensing.

    PubMed

    Gong, Cheng; Zhao, Yuejin; Dong, Liquan; Yu, Xiaomei; Chen, Ping; Liu, Weiwei

    2015-08-10

    Optical readout method plays a critical role in bimaterial cantilever array sensing system. The common optical readout methods are based on spectral plane filtering. In the paper an all-optical background subtraction readout approach inspired by total reflection and optical lever principle is presented for the bimaterial cantilever array sensing. Comparing with the spectral plane filtering methods the proposed approach eliminates digital subtraction operation by using optical total reflection instead of digital subtraction and avoids spectral filtering operation. An all-optical background subtraction directly-view infrared sensing system was developed to evaluate the approach. The infrared target can be directly acquired by the visible light CCD. The experimental results and analysis show its unique advantages. PMID:26367910

  1. All-optical scanhead for ultrasound and photoacoustic imaging-Imaging mode switching by dichroic filtering.

    PubMed

    Hsieh, Bao-Yu; Chen, Sung-Liang; Ling, Tao; Guo, L Jay; Li, Pai-Chi

    2014-03-01

    Ultrasound (US) and photoacoustic (PA) multimodality imaging has the advantage of combining good acoustic resolution with high optical contrast. The use of an all-optical scanhead for both imaging modalities can simplify integration of the two systems and miniaturize the imaging scanhead. Herein we propose and demonstrate an all-optical US/PA scanhead using a thin plate for optoacoustic generation in US imaging, a polymer microring resonator for acoustic detection, and a dichroic filter to switch between the two imaging modes by changing the laser wavelength. A synthetic-aperture focusing technique is used to improve the resolution and contrast. Phantom images demonstrate the feasibility of this design, and show that axial and lateral resolutions of 125 μm and 2.52°, respectively, are possible. PMID:25302154

  2. An all-optical modulation method in sub-micron scale.

    PubMed

    Yang, Longzhi; Pei, Chongyang; Shen, Ao; Zhao, Changyun; Li, Yan; Li, Xia; Yu, Hui; Li, Yubo; Jiang, Xiaoqing; Yang, Jianyi

    2015-01-01

    We report a theoretical study showing that by utilizing the illumination of an external laser, the Surface Plasmon Polaritons (SPP) signals on the graphene sheet can be modulated in the sub-micron scale. The SPP wave can propagate along the graphene in the middle infrared range when the graphene is properly doped. Graphene's carrier density can be modified by a visible laser when the graphene sheet is exfoliated on the hydrophilic SiO2/Si substrate, which yields an all-optical way to control the graphene's doping level. Consequently, the external laser beam can control the propagation of the graphene SPP between the ON and OFF status. This all-optical modulation effect is still obvious when the spot size of the external laser is reduced to 400 nm while the modulation depth is as high as 114.7 dB/μm. PMID:25777581

  3. Ultrafast, broadband, and configurable midinfrared all-optical switching in nonlinear graphene plasmonic waveguides

    NASA Astrophysics Data System (ADS)

    Ooi, Kelvin J. A.; Cheng, J. L.; Sipe, J. E.; Ang, L. K.; Tan, Dawn T. H.

    2016-07-01

    Graphene plasmonics provides a unique and excellent platform for nonlinear all-optical switching, owing to its high nonlinear conductivity and tight optical confinement. In this paper, we show that impressive switching performance on graphene plasmonic waveguides could be obtained for both phase and extinction modulations at sub-MW/cm2 optical pump intensities. Additionally, we find that the large surface-induced nonlinearity enhancement that comes from the tight confinement effect can potentially drive the propagating plasmon pump power down to the pW range. The graphene plasmonic waveguides have highly configurable Fermi-levels through electrostatic-gating, allowing for versatility in device design and a broadband optical response. The high capabilities of nonlinear graphene plasmonics would eventually pave the way for the adoption of the graphene plasmonics platform in future all-optical nanocircuitry.

  4. All-optical electromagnetically induced transparency using one-dimensional coupled microcavities.

    PubMed

    Naweed, Ahmer; Goldberg, David; Menon, Vinod M

    2014-07-28

    We report the first experimental realization of all-optical electromagnetically induced transparency (EIT) via a pair of coherently interacting SiO2 microcavities in a one-dimensional SiO2/Si3N4 photonic crystal consisting of a distributed Bragg reflector (DBR). The electromagnetic interactions between the coupled microcavities (CMCs), which possess distinct Q-factors, are controlled by varying the number of embedded SiO2/Si3N4 bilayers in the coupling DBR. In case of weak microcavity interactions, the reflectivity spectrum reveals an all-optical EIT resonance which splits into an Autler-Townes-like resonance under condition of strong microcavity coupling. Our results open up the way for implementing optical analogs of quantum coherence in much simpler one-dimensional structures. We also discuss potential applications of CMCs. PMID:25089499

  5. Passive all-optical polarization switch, binary logic gates, and digital processor.

    PubMed

    Zaghloul, Y A; Zaghloul, A R M; Adibi, A

    2011-10-10

    We introduce the passive all-optical polarization switch, which modulates light with light. That switch is used to construct all the binary logic gates of two or more inputs. We discuss the design concepts and the operation of the AND, OR, NAND, and NOR gates as examples. The rest of the 16 logic gates are similarly designed. Cascading of such gates is straightforward as we show and discuss. Cascading in itself does not require a power source, but feedback at this stage of development does. The design and operation of an SR Latch is presented as one of the popular basic sequential devices used for memory cells. That completes the essential components of an all-optical polarization digital processor. The speed of such devices is well above 10 GHz for bulk implementations and is much higher for chip-size implementations. In addition, the presented devices do have the four essential characteristics previously thought unique to the microelectronic ones. PMID:21997044

  6. Ultralow-light-level all-optical transistor in rubidium vapor

    SciTech Connect

    Jing, Jietai Zhou, Zhifan; Liu, Cunjin; Qin, Zhongzhong; Fang, Yami; Zhou, Jun; Zhang, Weiping

    2014-04-14

    An all-optical transistor (AOT) is a device in which one light beam can efficiently manipulate another. It is the foundational component of an all-optical communication network. An AOT that can operate at ultralow light levels is especially attractive for its potential application in the quantum information field. Here, we demonstrate an AOT driven by a weak light beam with an energy density of 2.5 × 10{sup −5} photons/(λ{sup 2}/2π) (corresponding to 6  yJ/(λ{sup 2}/2π) and about 800 total photons) using the double-Λ four-wave mixing process in hot rubidium vapor. This makes it a promising candidate for ultralow-light-level optical communication and quantum information science.

  7. An all-optical vector atomic magnetometer for fundamental physics applications

    NASA Astrophysics Data System (ADS)

    Wurm, David; Mateos, Ignacio; Zhivun, Elena; Patton, Brian; Fierlinger, Peter; Beck, Douglas; Budker, Dmitry

    2014-05-01

    We have developed a laboratory prototype of a compact all-optical vector magnetometer. Due to their high precision and absolute accuracy, atomic magnetometers are crucial sensors in fundamental physics experiments which require extremely stable magnetic fields (e.g., neutron EDM searches). This all-optical sensor will allow high-resolution measurements of the magnitude and direction of a magnetic field without perturbing the magnetic environment. Moreover, its absolute accuracy makes it calibration-free, an advantage in space applications (e.g., space-based gravitational-wave detection). Magnetometry in precision experiments or space applications also demands long-term stability and well-understood noise characteristics at frequencies below 10-4 Hz. We have characterized the low-frequency noise floor of this sensor and will discuss methods to improve its long-time performance.

  8. Model for multishot all-thermal all-optical switching in ferromagnets

    NASA Astrophysics Data System (ADS)

    Gorchon, J.; Yang, Y.; Bokor, J.

    2016-07-01

    All-optical magnetic switching (AOS) is a recently observed rich and puzzling phenomenon that offers promising technological applications. However, a fundamental understanding of the underlying mechanisms remains elusive. Here we present a model for multishot helicity-dependent AOS in ferromagnetic materials based on a purely heat-driven mechanism in the presence of magnetic circular dichroism (MCD). We predict that AOS should be possible with as little as 0.5% of MCD, after a minimum number of laser shots heat the sample close to the Curie temperature. Finally, we qualitatively reproduce the all-optically switched domain patterns observed experimentally by numerically simulating the result of multiple laser shots on an FePtC granular ferromagnetic film.

  9. An all-optical modulation method in sub-micron scale

    PubMed Central

    Yang, Longzhi; Pei, Chongyang; Shen, Ao; Zhao, Changyun; Li, Yan; Li, Xia; Yu, Hui; Li, Yubo; Jiang, Xiaoqing; Yang, Jianyi

    2015-01-01

    We report a theoretical study showing that by utilizing the illumination of an external laser, the Surface Plasmon Polaritons (SPP) signals on the graphene sheet can be modulated in the sub-micron scale. The SPP wave can propagate along the graphene in the middle infrared range when the graphene is properly doped. Graphene's carrier density can be modified by a visible laser when the graphene sheet is exfoliated on the hydrophilic SiO2/Si substrate, which yields an all-optical way to control the graphene's doping level. Consequently, the external laser beam can control the propagation of the graphene SPP between the ON and OFF status. This all-optical modulation effect is still obvious when the spot size of the external laser is reduced to 400 nm while the modulation depth is as high as 114.7 dB/μm. PMID:25777581

  10. F-Formation Detection: Individuating Free-Standing Conversational Groups in Images

    PubMed Central

    Setti, Francesco; Russell, Chris; Bassetti, Chiara; Cristani, Marco

    2015-01-01

    Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF). We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new), demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality. PMID:25996922

  11. F-formation detection: individuating free-standing conversational groups in images.

    PubMed

    Setti, Francesco; Russell, Chris; Bassetti, Chiara; Cristani, Marco

    2015-01-01

    Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF). We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new), demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality. PMID:25996922

  12. All-optical switching of diffraction gratings infiltrated with dye-doped liquid crystals

    NASA Astrophysics Data System (ADS)

    Lucchetta, D. E.; Vita, F.; Simoni, F.

    2010-12-01

    We report the realization and the characterization of an all-optical switching device based on a transmission grating recorded in a polymeric substrate infiltrated with a methyl red-doped liquid crystal. The properties of this highly nonlinear mixture are exploited to modulate the diffraction of the grating by a pump beam when a static electric field is applied. The behavior of the device is in agreement with the existing model for methyl red-doped liquid crystals.

  13. All-optical multibit address recognition at 20 Gb/s based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Wu, Jian; Lin, Jintong

    2005-04-01

    All-optical multibit address recognition at 20 Gb/s is demonstrated based on a special AND logic of terahertz optical asymmetric demultiplexer (TOAD). The semiconductor optical amplifier (SOA) used in the TOAD is biased at transparency status to accelerate the gain recovery. This is the highest bit rate that multibit address recognition is demonstrated with SOA-based interferometer. The experimental results show low pattern dependency. With this method, address recognition can be performed without separating address and payload beforehand.

  14. An All-Optical Microwave Mixer with 8db RF Gain

    NASA Technical Reports Server (NTRS)

    Shieh, W.; Yao, S. X.; Lutes, G.; Maleki, L.

    1997-01-01

    An all-optical microwave mixer with an 8dB RF gain is demonstrated by using a semiconductor optical amplifier (SOA). 6GHz RF signal on a 1312 nm optical carrier is up-converted and down-converted to 1GHZ and 11 GHz by a 5GHz local oscillation (LO) signal on a 1320 nm optical carrier. Such a carrier could readily extend to millimeter wave range.

  15. Realization of all-optical switch and diode via Raman gain process using a Kerr field

    NASA Astrophysics Data System (ADS)

    Abbas, Muqaddar; Qamar, Sajid; Qamar, Shahid

    2016-08-01

    The idea of optical photonic crystal, which is generated using two counter-propagating fields, is revisited to study gain-assisted all-optical switch and diode using Kerr field. Two counter-propagating fields with relative detuning Δ ν generate standing-wave field pattern which interacts with a four-level atomic system. The standing-wave field pattern acts like a static photonic crystal for Δ ν =0 , however, it behaves as a moving photonic crystal for Δ ν \

  16. Six-bit all-optical quantization using photonic crystal fiber with soliton self-frequency shift and pre-chirp spectral compression techniques

    NASA Astrophysics Data System (ADS)

    Kang, Zhe; Yuan, Jin-Hui; Li, Sha; Xie, Song-Lin; Yan, Bin-Bin; Sang, Xin-Zhu; Yu, Chong-Xiu

    2013-11-01

    In this paper, we propose an optical quantization scheme for all-optical analog-to-digital conversion that facilitates photonics integration. A segment of 10-m photonic crystal fiber with a high nonlinear coefficient of 62.8 W-1/km is utilized to realize large scale soliton self-frequency shift relevant to the power of the sampled optical signal. Furthermore, a 100-m dispersion-increasing fiber is used as the spectral compression module for further resolution enhancement. Simulation results show that 317-nm maximum wavelength shift is realized with 1550-nm initial wavelength and 6-bit quantization resolution is obtained with a subsequent spectral compression process.

  17. Dimensioning of 10 Gbit/s all-optical packet switched networks based on optical label swapping routers with multistage 2R regeneration.

    PubMed

    Puerto, G; Ortega, B; Manzanedo, M D; Martínez, A; Pastor, D; Capmany, J; Kovacs, G

    2006-10-30

    This paper describes both the experimental and theoretical investigations on the cascadability of all-optical routers in optical label swapping networks incorporating a multistage wavelength conversion with 2R regeneration. A full description of a novel experimental setup allows the packet by packet measurement up to 16 hops with 10 Gb/s payload showing 1 dB penalty with 10(-12) bit error rate. Similarly, the simulations on the system allow a prediction on the cascadability of the router up to 64 hops. PMID:19529426

  18. All-optical single-sideband upconversion with an optical interleaver and a semiconductor optical amplifier for radio-over-fiber applications.

    PubMed

    Kim, Hyoung-Jun; Song, Jong-In

    2009-06-01

    We propose and experimentally demonstrate an all-optical upconverter for the generation of an optical single-sideband (OSSB) signal in radio-over-fiber (RoF) systems. The OSSB signal, which is required for overcoming the fiber chromatic dispersion problem in RoF systems, is generated by using an all-optical SSB upconverter consisting of an optical interleaver and a semiconductor optical amplifier. With this upconversion technique, OSSB radio frequency (RF) signals with an RF frequency ranging from 15 GHz to 42.5 GHz are generated by mixing an optical intermediate frequency (IF) signal (1 GHz) with an optical local oscillator signal and transmitted over a 46 km standard single-mode fiber. The OSSB RF signal generated by this upconversion technique shows negligible dispersion-induced carrier suppression effects, which are usually observed for an optical double-sideband RF signal. The all-optical SSB upconverter provides high conversion efficiency of up to 29 dB and a sufficiently large spurious free dynamic range of 82 dB.Hz(2/3) for microcellular personal communication system applications. PMID:19506630

  19. Chip-integrated ultrawide-band all-optical logic comparator in plasmonic circuits

    PubMed Central

    Lu, Cuicui; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

    2014-01-01

    Optical computing opens up the possibility for the realization of ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic comparator is one of the indispensable core components of optical computing systems. Unfortunately, up to now, no any nanoscale all-optical logic comparator suitable for on-chip integration applications has been realized experimentally. Here, we report a subtle and effective technical solution to circumvent the obstacles of inherent Ohmic losses of metal and limited propagation length of SPPs. A nanoscale all-optical logic comparator suitable for on-chip integration applications is realized in plasmonic circuits directly. The incident single-bit (or dual-bit) logic signals can be compared and the comparison results are endowed with different logic encodings. An ultrabroad operating wavelength range from 700 to 1000 nm, and an ultrahigh output logic-state contrast-ratio of more than 25 dB are realized experimentally. No high power requirement is needed. Though nanoscale SPP light source and the logic comparator device are integrated into the same plasmonic chip, an ultrasmall feature size is maintained. This work not only paves a way for the realization of complex logic device such as adders and multiplier, but also opens up the possibility for realizing quantum solid chips based on plasmonic circuits. PMID:24463956

  20. All-optical tuning of a nonlinear silicon microring assisted microwave photonic filter: theory and experiment.

    PubMed

    Long, Yun; Wang, Jian

    2015-07-13

    We propose and demonstrate an all-optical tuning mechanism to tune the response of a microwave photonic filter (MPF) based on a nonlinear silicon microring resonator (MRR). The tuning mechanism relies on the optical nonlinearities induced resonant wavelength shift in the silicon MRR, leading to the change of frequency difference between the optical carrier frequency and resonant frequency of the silicon MRR. A detailed theoretical model is established to describe the operation of the proposed all-optical tunable MPF. Two cases are studied in the experiment, i.e. the optical carrier frequency is located at the left or right side of the MRR resonant frequency. Both forward and backward pumping configurations in each case are demonstrated. Using the fabricated silicon MRR and exploiting light to control light, the central frequency of the notch MPF can be flexibly tuned by adjusting the pump light power. Moreover, the presented all-optical tuning mechanism might also facilitate interesting applications such as microwave switching and microwave modulation. PMID:26191838

  1. Software Defined Networking (SDN) controlled all optical switching networks with multi-dimensional switching architecture

    NASA Astrophysics Data System (ADS)

    Zhao, Yongli; Ji, Yuefeng; Zhang, Jie; Li, Hui; Xiong, Qianjin; Qiu, Shaofeng

    2014-08-01

    Ultrahigh throughout capacity requirement is challenging the current optical switching nodes with the fast development of data center networks. Pbit/s level all optical switching networks need to be deployed soon, which will cause the high complexity of node architecture. How to control the future network and node equipment together will become a new problem. An enhanced Software Defined Networking (eSDN) control architecture is proposed in the paper, which consists of Provider NOX (P-NOX) and Node NOX (N-NOX). With the cooperation of P-NOX and N-NOX, the flexible control of the entire network can be achieved. All optical switching network testbed has been experimentally demonstrated with efficient control of enhanced Software Defined Networking (eSDN). Pbit/s level all optical switching nodes in the testbed are implemented based on multi-dimensional switching architecture, i.e. multi-level and multi-planar. Due to the space and cost limitation, each optical switching node is only equipped with four input line boxes and four output line boxes respectively. Experimental results are given to verify the performance of our proposed control and switching architecture.

  2. All-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer-based tree architecture

    NASA Astrophysics Data System (ADS)

    Gayen, Dilip Kumar; Nath Roy, Jitendra

    2008-03-01

    An all-optical arithmetic unit with the help of terahertz-optical-asymmetric-demultiplexer (TOAD)-based tree architecture is proposed. We describe the all-optical arithmetic unit by using a set of all-optical multiplexer, all-optical full-adder, and optical switch. The all-optical arithmetic unit can be used to perform a fast central processor unit using optical hardware components. We have tried to exploit the advantages of both optical tree architecture and TOAD-based switch to design an integrated all-optical circuit that can perform binary addition, addition with carry, subtract with borrow, subtract (2's complement), double, increment, decrement, and transfer operations.

  3. Conversion of Input Data between KENO V.a and MCNP File Formats, Version 5L.

    2007-10-31

    Version 00 The KENO2MCNP program was written to convert KENO V.a input files to MCNP Format. This program currently only works with KENO Va geometries and will not work with geometries that contain more than a single array. A C++ graphical user interface was created that was linked to Fortran routines from KENO V.a that read the material library and Fortran routines from the MCNP Visual Editor that generate the MCNP input file. Either SCALEmore » 5.0 or SCALE 5.1 cross section files will work with this release. This version of KENO2MCNP was tested with CCC-730/MCNP5 1.40 and with CCC-725/SCALE5.0 and CCC-732/SCALE 5.1. Note that this distribution does not include either MCNP or SCALE, which are available separately through either RSICC or the NEA Data Bank.« less

  4. High Temperature Raman Spectroscopy Study of the Conversion of Formate into Oxalate: Search for the Elusive CO 2 2 - Intermediate

    NASA Astrophysics Data System (ADS)

    Ryan, Charles; Mead, Anna; Lakkaraju, Prasad; Kaczur, Jerry; Bennett, Christopher; Dobbins, Tabbetha

    Research on conversion of carbon dioxide into chemicals and fuels has the potential to address three problems of global relevance. (a) By removing carbon dioxide from the atmosphere, we are able to reduce the amount of greenhouse gases in the atmosphere, (b) by converting carbon dioxide into fuels, we are providing pathways for renewable energy sources, (c) by converting carbon dioxide into C2 and higher order compounds, and we are able to generate valuable precursors for organic synthesis. Formate salts are formed by the electrochemical reduction of carbon dioxide in aqueous media. However, in order to increase the utilization of carbon dioxide, methods need to be developed for the conversion of formate into compounds containing two carbon atoms such as oxalate or oxalic acid. Recently, we examined the thermal conversion of sodium formate into sodium oxalate utilizing a hydride ion catalyst. The proposed mechanism for this reaction involves the carbon dioxide dianion. Currently at NASA Goddard Space Flight Center.

  5. Support- dependent evolution of oxidation state and nanoassembly formation of subnanometer copper clusters under carbon dioxide conversion conditions

    NASA Astrophysics Data System (ADS)

    Halder, Avik; Yang, Bing; Kolipaka, Karthika L.; Pellin, Michael; Seifert, Soenke; Vajda, Stefan; Materials Science Division Team

    Size- and support- dependence of the properties of copper clusters have been investigated during carbon dioxide conversion with hydrogen at high reactant concentrations and atmospheric pressure. The model catalyst systems were prepared by depositing size-selected Cun clusters (n = 3, 4, 12 and 20) on various amorphous metal oxide (Al2O3, ZnO, and ZrO2) , and carbon-based (UNCD = ultrananocrystaline diamond) supports. During the temperature ramp, the evolution of the chemical state and size of the particles were characterized by in situ grazing incidence X-ray absorption near edge structure (GIXANES), and grazing incidence small angle X-ray scattering (GISAXS) respectively. Under reaction conditions the initially oxidized Cu clusters reduced at various temperatures depending on cluster size and support. Clusters supported on ZnO and UNCD were found to be sinter-resistant under reactive gases at elevated temperatures and atmospheric pressures, whereas on ZrO2 support the clusters formed stable aggregates. Clusters on Al2O3 support demonstrated unique properties, where a formation of a nanostructure was observed during heating, which then disintegrated during the cool down. Under applied conditions, Cu4 clusters on Al2O3 were found to be the most efficient in methanol formation.

  6. All optical up-converted signal generation with high dispersion tolerance using frequency quadrupling technique for radio over fiber system

    NASA Astrophysics Data System (ADS)

    Gu, Yiying; Zhao, Jiayi; Hu, Jingjing; Kang, Zijian; Zhu, Wenwu; Fan, Feng; Han, Xiuyou; Zhao, Mingshan

    2016-05-01

    A novel all optical up-converted signal generation scheme with optical single-sideband (OSSB) technique for radio over fiber (RoF) application is presented and experimentally demonstrated using low-bandwidth devices. The OSSB signal is generated by one low-bandwidth intensity LiNbO3 Mach-Zehnder modulator (LN-MZM) under frequency quadrupling modulation scheme and one low-bandwidth LN-MZM under double sideband carrier suppressed modulation (DSB-CS) scheme. The proposed all OSSB generation scheme is capable of high tolerance of fiber chromatic dispersion induced power fading (DIPF) effect. Benefiting from this novel OSSB generation scheme, a 26 GHz radio frequency (RF) signal up-conversion is realized successfully when one sideband of the optical LO signal is reused as the optical carrier for intermediate frequency (IF) signal modulation. The received vector signal transmission over long distance single-mode fiber (SMF) shows negligible DIPF effect with the error vector magnitude (EVM) of 15.7% rms. In addition, a spurious free dynamic range (SFDR) of the OSSB up-converting system is measured up to 81 dB Hz2/3. The experiment results indicate that the proposed system may find potential applications in future wireless communication networks, especially in microcellular personal communication system (MPCS).

  7. All-Optical Half-Adder Using All-Optical XOR and AND Gates for Optical Generation of "Sum" and "Carry"

    NASA Astrophysics Data System (ADS)

    Menezes, J. W. M.; Fraga, W. B.; Ferreira, A. C.; Guimarães, G. F.; Filho, A. F. G. F.; Sobrinho, C. S.; Sombra, A. S. B.

    2010-07-01

    In this article, a numerical simulation study using the symmetric planar three-core non-linear directional coupler, operating with a short light pulse (2 ps), for the implementation of an all-optical half-adder is presented. The half-adder is the key building block for many digital processing functions such as shift register, binary counter, and serial parallel data converters. Optical couplers are an important component for application in optical fiber telecommunication systems and all integrated optical circuits because of very high switching speeds (as high as the femto-second range). In this numerical simulation, the symmetric planar three-core non-linear directional coupler presents a planar symmetrical structure with three cores in a parallel equidistant arrangement, three logical inputs (CP, A, and B), and two output logic functions (C and S). The CP(ΔΦ) input is a control pulse with a phase difference ΔΦ = Δθπ (0 ≤ Δθ ≤ 2) between inputs A and B (logical inputs of the half-adder) and one amplitude discriminator circuit. The half-adder uses two output logic functions of Sum(S) and Carry(C), which can be demonstrated by using XOR and AND gates, respectively. For the half-adder, the phase [ΔΦMIN, ΔΦMAX] intervals are studied, allowing the operation of the device as a half-adder. For the selected range of CP(ΔΦBETTER), the extinction ratio was studied, the compression factors for both Sum(S) and Carry(C) outputs of the symmetric planar three-core non-linear directional coupler.

  8. Anomalous nonlinear absorption in epsilon-near-zero materials: optical limiting and all-optical control.

    PubMed

    Vincenti, M A; de Ceglia, D; Scalora, Michael

    2016-08-01

    We investigate nonlinear absorption in films of epsilon-near-zero materials. The combination of large local electric fields at the fundamental frequency and material losses at the harmonic frequencies induce unusual intensity-dependent phenomena. We predict that the second-order nonlinearity of a low-damping, epsilon-near-zero slab produces an optical limiting effect that mimics a two-photon absorption process. Anomalous absorption profiles that depend on low permittivity values at the pump frequency are also predicted for third-order nonlinearities. These findings suggest new opportunities for all-optical light control and novel ways to design reconfigurable and tunable nonlinear devices. PMID:27472631

  9. First demonstration of a staged all-optical laser wakefield acceleration

    SciTech Connect

    Kaganovich, D.; Ting, A.; Gordon, D.F.; Hubbard, R.F.; Jones, T.G.; Zigler, A.; Sprangle, P.

    2005-10-01

    A proof-of-principle experiment on staged all-optical laser wakefield acceleration was performed at the Naval Research Laboratory. Electrons with <1 MeV energy created by the interaction of a 2 TW laser beam with a nitrogen gas jet were injected and accelerated to more than 20 MeV in a plasma wakefield generated by a 10 TW laser beam in a helium gas jet. The energy gain occurred in a narrow time window of 3 ps between the injection and acceleration laser beams, and within a tight spatial alignment of {approx}10 {mu}m.

  10. All-Optical Steering of Laser-Wakefield-Accelerated Electron Beams

    SciTech Connect

    Popp, A.; Osterhoff, J.; Major, Zs.; Hoerlein, R.; Fuchs, M.; Weingartner, R.; Krausz, F.; Gruener, F.; Karsch, S.; Vieira, J.; Marti, M.; Fonseca, R. A.; Martins, S. F.; Silva, L. O.

    2010-11-19

    We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations.

  11. All-optical steering of laser-wakefield-accelerated electron beams.

    PubMed

    Popp, A; Vieira, J; Osterhoff, J; Major, Zs; Hörlein, R; Fuchs, M; Weingartner, R; Rowlands-Rees, T P; Marti, M; Fonseca, R A; Martins, S F; Silva, L O; Hooker, S M; Krausz, F; Grüner, F; Karsch, S

    2010-11-19

    We investigate the influence of a tilted laser-pulse-intensity front on laser-wakefield acceleration. Such asymmetric light pulses may be exploited to obtain control over the electron-bunch-pointing direction and in our case allowed for reproducible electron-beam steering in an all-optical way within an 8 mrad opening window with respect to the initial laser axis. We also discovered evidence of collective electron-betatron oscillations due to off-axis electron injection into the wakefield induced by a pulse-front tilt. These findings are supported by 3D particle-in-cell simulations. PMID:21231309

  12. Coherent-population-trapping resonances with linearly polarized light for all-optical miniature atomic clocks

    SciTech Connect

    Zibrov, Sergei A.; Velichansky, Vladimir L.; Novikova, Irina; Phillips, David F.; Walsworth, Ronald L.; Zibrov, Alexander S.; Taichenachev, Alexey V.; Yudin, Valery I.

    2010-01-15

    We present a joint theoretical and experimental characterization of the coherent population trapping (CPT) resonance excited on the D{sub 1} line of {sup 87}Rb atoms by bichromatic linearly polarized laser light. We observe high-contrast transmission resonances (up to approx =25%), which makes this excitation scheme promising for miniature all-optical atomic clock applications. We also demonstrate cancellation of the first-order light shift by proper choice of the frequencies and relative intensities of the two laser-field components. Our theoretical predictions are in good agreement with the experimental results.

  13. Three-photon-absorption resonance for all-optical atomic clocks

    SciTech Connect

    Zibrov, Sergei; Novikova, Irina; Phillips, David F.; Taichenachev, Aleksei V.; Yudin, Valeriy I.; Walsworth, Ronald L.; Zibrov, Alexander S.

    2005-07-15

    We report an experimental study of an all-optical three-photon-absorption resonance (known as an 'N resonance') and discuss its potential application as an alternative to atomic clocks based on coherent population trapping. We present measurements of the N-resonance contrast, width and light shift for the D{sub 1} line of {sup 87}Rb with varying buffer gases, and find good agreement with an analytical model of this resonance. The results suggest that N resonances are promising for atomic clock applications.

  14. All-optical UWB signal generation and multicasting using a nonlinear optical loop mirror.

    PubMed

    Huang, Tianye; Li, Jia; Sun, Junqiang; Chen, Lawrence R

    2011-08-15

    An all-optical scheme for ultra-wideband (UWB) signal generation (positive and negative monocycle and doublet pulses) and multicasting using a nonlinear optical loop mirror (NOLM) is proposed and demonstrated. Five UWB signals (1 monocycle and 4 doublet pulses) are generated simultaneously from a single Gaussian optical pulse. The fractional bandwidths of the monocycle pulses are approximately 100% while those of the doublet pulses range from 100% to 133%. The UWB signals are then modulated using a 2(15)-1 pseudorandom bit sequence (PRBS) and error-free performance for each multicast channel is obtained. PMID:21934951

  15. All-optical UWB signal generation and multicasting using a nonlinear optical loop mirror

    NASA Astrophysics Data System (ADS)

    Huang, Tianye; Li, Jia; Sun, Junqiang; Chen, Lawrence R.

    2011-08-01

    An all-optical scheme for ultra-wideband (UWB) signal generation (positive and negative monocycle and doublet pulses) and multicasting using a nonlinear optical loop mirror (NOLM) is proposed and demonstrated. Five UWB signals (1 monocycle and 4 doublet pulses) are generated simultaneously from a single Gaussian optical pulse. The fractional bandwidths of the monocycle pulses are approximately 100% while those of the doublet pulses range from 100% to 133%. The UWB signals are then modulated using a 215 - 1 pseudorandom bit sequence (PRBS) and error-free performance for each multicast channel is obtained.

  16. Realization of an all-optical zero to pi cross-phase modulation jump.

    PubMed

    Camacho, Ryan M; Dixon, P Ben; Glasser, Ryan T; Jordan, Andrew N; Howell, John C

    2009-01-01

    We report on the experimental demonstration of an all-optical pi cross-phase modulation jump. By performing a preselection, an optically induced unitary transformation, and then a postselection on the polarization degree of freedom, the phase of the output beam acquires either a zero or pi phase shift (with no other possible values). The postselection results in optical loss in the output beam. An input state may be chosen near the resulting phase singularity, yielding a pi phase shift even for weak interaction strengths. The scheme is experimentally demonstrated using a coherently prepared dark state in a warm atomic cesium vapor. PMID:19257193

  17. All-optical trion generation in single-walled carbon nanotubes.

    PubMed

    Santos, Silvia M; Yuma, Bertrand; Berciaud, Stéphane; Shaver, Jonah; Gallart, Mathieu; Gilliot, Pierre; Cognet, Laurent; Lounis, Brahim

    2011-10-28

    We present evidence of all-optical trion generation and emission in pristine single-walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large cw excitation intensity range, show trion emission peaks redshifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing for determination of electron-hole exchange interaction and trion binding energy contributions. Luminescence data together with ultrafast pump-probe experiments on chirality-sorted bulk samples suggest that exciton-exciton annihilation processes generate dissociated carriers that allow for trion creation upon a subsequent photon absorption event. PMID:22107671

  18. Spin-based all-optical quantum computation with quantum dots: Understanding and suppressing decoherence

    SciTech Connect

    Calarco, T.; Datta, A.; Fedichev, P.; Zoller, P.; Pazy, E.

    2003-07-01

    We present an all-optical implementation of quantum computation using semiconductor quantum dots. Quantum memory is represented by the spin of an excess electron stored in each dot. Two-qubit gates are realized by switching on trion-trion interactions between different dots. State selectivity is achieved via conditional laser excitation exploiting Pauli exclusion principle. Read out is performed via a quantum-jump technique. We analyze the effect on our scheme's performance of the main imperfections present in real quantum dots: exciton decay, hole mixing, and phonon decoherence. We introduce an adiabatic gate procedure that allows one to circumvent these effects and evaluate quantitatively its fidelity.

  19. Single Shot Radiography Using an All-optical Compton Backscattering Source

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Gautier, J.; Lifschitz, A.; Conejero, E.; Ruiz, C.; Malka, V.; Rousse, A.; Phuoc, K. Ta

    The development of compact laser-based synchrotron sources is a field of active research. Here we present recent results on an all-optical Compton backscattering source using laser-accelerated electrons and a plasma mirror, as introduced in [K. Ta Phuoc et al., Nature Photonics 6 (5) (2012) 308-311]. Scattering of quasi-monoenergetic electrons of up to 200 MeV energy with their proper drive-beam leads to emission of femtosecond X-ray pulses, whose energies exceed 100 keV. We demonstrate that the photon yield from the source is sufficient to illuminate a centimeter-size sample placed 90 centimeters behind the source.

  20. All-optical flip-flop operation based on bistability in V-cavity laser.

    PubMed

    Wu, Yingchen; Zhu, Yu; Liao, Xiaolu; Meng, Jianjun; He, Jian-Jun

    2016-06-13

    We theoretically analyzed and experimentally demonstrated an injection-locking based all-optical flip-flop memory using a simple and compact tunable V-cavity laser (VCL). A bistable region in the tuning characteristics of the VCL is employed for the flip-flop operation. The state of the VCL can be set and reset by injecting signal pulses at two different wavelengths. The pulse power for both set and reset signal is only about 1 pJ. Short response times of about 150 ps are measured for storing and erasing. PMID:27410271

  1. All-optical transistor based on a cavity optomechanical system with a Bose-Einstein condensate

    SciTech Connect

    Chen, Bin; Jiang, Cheng; Li, Jin-Jin; Zhu, Ka-Di

    2011-11-15

    We propose a scheme of an all-optical transistor based on a coupled Bose-Einstein condensate cavity system. The calculated results show that, in such an optomechanical system, the transmission of the probe beam is strongly dependent on the optical pump power. Therefore, the optical pump field can serve as a ''gate'' field of the transistor, effectively controlling the propagation of the probe field (the ''signal'' field). The scheme proposed here may have potential applications in optical communication and quantum information processing.

  2. All-optical atom surface traps implemented with one-dimensional planar diffractive microstructures.

    PubMed

    Alloschery, O; Mathevet, R; Weiner, J; Lezec, H J

    2006-12-25

    We characterize the loading, containment and optical properties of all-optical atom traps implemented by diffractive focusing with one-dimensional (1D) microstructures milled on gold films. These on-chip Fresnel lenses with focal lengths of the order of a few hundred microns produce optical-gradient-dipole traps. Cold atoms are loaded from a mirror magneto-optical trap (MMOT) centered a few hundred microns above the gold mirror surface. Details of loading optimization are reported and perspectives for future development of these structures are discussed. PMID:19532148

  3. All-optical mitigation of amplitude and phase-shift drift noise in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Rocha, Peterson; Gallep, Cristiano M.; Conforti, Evandro

    2015-10-01

    An all-optical scheme aimed at minimizing distortions induced by semiconductor optical amplifiers (SOAs) over modulated optical carriers is presented. The scheme employs an additional SOA properly biased to act as a saturated absorber, and thus counteract the distortions induced by the first amplifying device. The scheme here is demonstrated in silico, for 40 and 100 Gb/s (10 and 25 Gbaud, 16 QAM), with reasonable total gain (>20 dB) for symbol error rate below the forward error correction limit.

  4. Microwave photonic quadrature filter based on an all-optical programmable Hilbert transformer.

    PubMed

    Huang, Thomas X H; Yi, Xiaoke; Minasian, Robert A

    2011-11-15

    A microwave photonic quadrature filter, new to our knowledge, based on an all-optical Hilbert transformer is presented. It is based on mapping of a Hilbert transform transfer function between the optical and electrical domains, using a programmable Fourier-domain optical processor and high-speed photodiodes. The technique enables the realization of an extremely wide operating bandwidth, tunable programmable bandwidth, and a highly precise amplitude and phase response. Experimental results demonstrate a microwave quadrature filter from 10 to 20 GHz, which achieves an amplitude imbalance of less than ±0.23 dB and a phase imbalance of less than ±0.5°. PMID:22089590

  5. All optical controlled photonic integrated circuits using azo dye functionized sol-gel material

    NASA Astrophysics Data System (ADS)

    Ke, Xianjun

    The main focus of this dissertation is development and characterization of all-optical controllable azo dye functionized sol gel material, demonstrating a PIC fabrication technique on glass substrate using such material, and exploration and feasibility demonstration of three PIC functional devices namely optical variable attenuator, optical switches, and optical tunable filters using the material. The realization of all the devices in this dissertation are based on one material: dye functionalized sol-gel material. A photochromic sol-gel material functionalized with azo dye was synthesized and characterized. It possesses a photochromic characteristic under the control of green laser beam illumination. The material characteristics suggest the possibility of a new promising material platform candidate for the fabrication of alloptical controlled photonic integrated circuits. As the first potential application of the dye functionalized sol-gel material, an alloptical variable attenuator was designed and demonstrated. The optical variable attenuation is achieved in Mach-Zehnder interferometric configuration through all-optical modulation of sol-gel waveguide phase shifters. A 2 x 2 optical switch based on multimode interference (MMI) waveguide structure is proposed in the dissertation. The schematic configuration of the optical switch consists of a cascade of two identical MMIs with two all-optical controlled phase shifters realized by using the photochromic sol-gel material. The cross or bar switch state of the optical switch is determined by the phase difference between the two sol-gel waveguide phase shifters. An all-optical tunable filter is designed and its feasibility demonstrated by using the sol-gel photochromic material. Except for the phase change demonstrated on sol-gel waveguide phase shifters, dynamic gratings were observed on sol-gel film when exposed to two interference beams. This reveals the possibility of realizing Bragg grating-based tunable filters

  6. All-optical packet header and payload separation for un-slotted optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zhang, Min; Ye, Peida

    2005-11-01

    A novel all-optical header and payload separation technique that can be utilized in un-slotted optical packet switched networks is presented. The technique uses a modified TOAD for packet header extraction with differential modulation scheme and two SOAs that perform a simple XOR operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and need not any additional continuous pulses. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the parameters of the system are discussed and designed to optimize the operation performance.

  7. All-optical repetition rate multiplication of pseudorandom bit sequences by employing power coupler and equalizer

    NASA Astrophysics Data System (ADS)

    Sun, Zhenchao; Wang, Zhi; Wu, Chongqing; Wang, Fu; Li, Qiang

    2015-10-01

    A scheme for all-optical repetition rate multiplication of pseudorandom bit sequences (PRBS) is demonstrated with a precision delay feedback loop cascaded with a terahertz optical asymmetric demultiplexer (TOAD)-based power equalizer. Its feasibility has been verified by experiments, which show a multiplication for PRBS at cycle 2^7-1 from 2.5 to 10 Gb/s. This scheme can be employed for the rate multiplication of a much longer cycle PRBS at a much higher bit rate over 40 Gb/s if the time-delay, the loss, and the dispersion of an optical delay line are all precisely managed.

  8. Design of polarization encoded all-optical 4-valued MAX logic gate and its applications

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay; Nath Roy, Jitendra

    2013-07-01

    Quaternary maximum (QMAX) gate is one type of multi-valued logic gate. An all-optical scheme of polarization encoded quaternary (4-valued) MAX logic gate with the help of Terahertz Optical Asymmetric Demultiplexer (TOAD) based fiber interferometric switch is proposed and described. For the quaternary information processing in optics, the quaternary number (0, 1, 2, 3) can be represented by four discrete polarized states of light. Numerical simulation result confirming the described methods is given in this paper. Some applications of MAX gate in logical operation and memory device are also given.

  9. Low light level all-optical switching in a four-level atom-cavity system

    NASA Astrophysics Data System (ADS)

    Duan, Yafan; Lin, Gongwei; Zhang, Shicheng; Niu, Yueping; Gong, Shangqing

    2016-01-01

    We report on an all-optical switching in a double ∧ four-level atom-cavity system both theoretically and experimentally. In this system, an extra coherence between two ground states is induced by two coupling lasers, thus the loss of the cavity field decreases. Then, we can use one weak field to control another weak field at low light levels. Compared to the three-level atom-cavity system, the power of the switching laser can be much weaker in the four-level atom-cavity system.

  10. Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

    NASA Astrophysics Data System (ADS)

    Sharma, Rituraj; Prasai, Kiran; Drabold, D. A.; Adarsh, K. V.

    2015-07-01

    Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.

  11. All-optical tunable multilevel amplitude regeneration based on coherent wave mixing using a polarizer.

    PubMed

    Bakhtiari, Zahra; Sawchuk, Alexander A

    2015-04-20

    We describe and demonstrate an all-optical tunable phase- preserving scheme for multilevel amplitude regeneration based on coherent optical wave mixing using a polarizer for optical star 8-quadrature-amplitude modulation (star-8QAM) and star-16QAM signals with a power ratio of 1:5. Amplitude noise can be efficiently suppressed on both amplitude levels. A regeneration factor of nearly 5 for the higher-amplitude level of star-8QAM and 3 for lower-amplitude level are achieved. The system robustness against nonlinear phase noise originating from the Gordon-Mollenauer effect in a 150 km transmission line is investigated using the proposed amplitude regenerator. PMID:25969093

  12. All-optical KarhunenLoeve Transform Using Multimode Interference Structures on Silicon Nanowires

    NASA Astrophysics Data System (ADS)

    Le, Trung-Thanh

    2011-12-01

    A variety of unitary transforms have attracted considerable attention for their application in data, image compression and other signal processing applications. Among many transforms, the KarhunenLoeve transform (KLT) is known to be optimal because of its advantages of computational efficiency, residual correlation and rate distortion criterion. In this paper, it is shown that the all-optical KarhunenLoeve transform can be realized using multimode interference (MMI) structures on silicon wire waveguides. The transfer matrix method (TMM) and the beam propagation method (BPM) are used to verify and optimally design the proposed devices.

  13. Synthesis and characterization of azo-containing organometallic thin films for all optical switching applications

    NASA Astrophysics Data System (ADS)

    Gatri, R.; Fillaut, J.-L.; Mysliwiec, J.; Szukalski, A.; Bartkiewicz, S.; El-Ouazzani, H.; Guezguez, I.; Khammar, F.; Sahraoui, B.

    2012-05-01

    Novel photoresponsive materials based on azo-containing bifunctional ruthenium-acetylides have been synthesized. All optical switching based on the Optical Kerr Effect in the organometallic thin films based on ruthenium(II) acetylides containing an azobenzene moiety as a photochromic unit in the main pi-conjugated system dispersed in a poly(methyl methacrylate) matrix has been observed. The excitation beam was delivered from a picosecond laser at wavelength 532 nm while dynamics of induced sample birefringence was probed by a non-absorbed linearly polarized beam of cw He-Ne laser (632.8 nm). The influence of ruthenium part on dynamics of molecular motions has been shown.

  14. Ultrafast all-optical NOR gate based on semiconductor optical amplifier and fiber delay interferometer

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Zhang, Xinliang; Liu, Deming; Huang, Dexiu

    2006-10-01

    An ultrafast all-optical logic NOR gate based on a semiconductor optical amplifier (SOA) and a fiber delay interferometer (FDI) is presented. For high-speed input return-to-zero (RZ) signal, nonreturn-to-zero (NRZ) switching windows which satisfy Boolean NOR operation can be formed by properly choosing the delay time and the phase shift of FDI. 40Gb/s NOR operation has been demonstrated successfully with low control optical power. The factors that degrade the NOR operation have been discussed.

  15. Low-power all-optical tunable plasmonic-mode coupling in nonlinear metamaterials

    SciTech Connect

    Zhang, Fan; Yang, Hong; Hu, Xiaoyong E-mail: qhgong@pku.edu.cn; Gong, Qihuang E-mail: qhgong@pku.edu.cn

    2014-03-31

    All-optical tunable plasmonic-mode coupling is realized in a nonlinear photonic metamaterial consisting of periodic arrays of gold asymmetrically split ring resonators, covered with a poly[(methyl methacrylate)-co-(disperse red 13 acrylate)] azobenzene polymer layer. The third-order optical nonlinearity of the azobenzene polymer is enormously enhanced by using resonant excitation. Under excitation with a 17-kW/cm{sup 2}, 532-nm pump light, plasmonic modes shift by 51 nm and the mode interval is enlarged by 30 nm. Compared with previous reports, the threshold pump intensity is reduced by five orders of magnitude, while extremely large tunability is maintained.

  16. All-optical athermalization of infrared imaging systems using thermally dependent binary phase masks

    NASA Astrophysics Data System (ADS)

    Elmalem, Shay; Marom, Emanuel

    2016-06-01

    Lenses used in many infrared (IR) imaging systems are temperature sensitive. One of the most popular IR optical materials for lens fabrication is germanium; nevertheless, it exhibits a strong temperature dependent refractive index, causing significant thermal focal shift which in turn results in image blur. An all-optical solution for IR lens athermalization with no moving parts based on a thermally dependent binary phase mask is hereby proposed and analyzed. It allows high quality imaging to be obtained for a wide range of temperature variations, with minimal performance degradation at nominal temperature conditions.

  17. Thermal lens and all optical switching of new organometallic compound doped polyacrylamide gel

    NASA Astrophysics Data System (ADS)

    Badran, Hussain Ali

    In this work thermal lens spectrometry (TLS) is applied to investigate the thermo-optical properties of new organometallic compound containing azomethine group, Dichloro bis [2-(2-hydroxybenzylideneamino)-5-methylphenyl] telluride platinum(II), doped polyacrylamide gel using transistor-transistor logic (TTL) modulated cw 532 nm laser beam as an excitation beam modulated at 10 Hz frequency and probe beam wavelength 635 nm at 14 mW. The technique is applied to determine the thermal diffusivities, ds/dT and the linear thermal expansion coefficient of the sample. All-optical switching effects with low background and high stability are demonstrated.

  18. Ultrafast defect dynamics: A new approach to all optical broadband switching employing amorphous selenium thin films

    SciTech Connect

    Sharma, Rituraj; Adarsh, K. V. E-mail: adarsh@iiserb.ac.in; Prasai, Kiran; Drabold, D. A. E-mail: adarsh@iiserb.ac.in

    2015-07-15

    Optical switches offer higher switching speeds than electronics, however, in most cases utilizing the interband transitions of the active medium for switching. As a result, the signal suffers heavy losses. In this article, we demonstrate a simple and yet efficient ultrafast broadband all-optical switching on ps timescale in the sub-bandgap region of the a-Se thin film, where the intrinsic absorption is very weak. The optical switching is attributed to short-lived transient defects that form localized states in the bandgap and possess a large electron-phonon coupling. We model these processes through first principles simulation that are in agreement with the experiments.

  19. All-optical encryption based on interleaved waveband switching modulation for optical network security.

    PubMed

    Fok, Mable P; Prucnal, Paul R

    2009-05-01

    All-optical encryption for optical code-division multiple-access systems with interleaved waveband-switching modulation is experimentally demonstrated. The scheme explores dual-pump four-wave mixing in a 35 cm highly nonlinear bismuth oxide fiber to achieve XOR operation of the plaintext and the encryption key. Bit 0 and bit 1 of the encrypted data are represented by two different wavebands. Unlike on-off keying encryption methods, the encrypted data in this approach has the same intensity for both bit 0 and bit 1. Thus no plaintext or ciphertext signatures are observed. PMID:19412257

  20. Realization of all-optical AND-OR logic gates using the Z-scan method

    NASA Astrophysics Data System (ADS)

    Dhinaa, A. N.; Palanisamy, P. K.; Murali, K.

    2013-10-01

    The NLO properties of organic materials have been studied with the single-beam Z-scan technique using a CW laser beam. A He-Ne laser operated at 632.8 nm with a power output of 12 mW is used for this study. A closed-aperture setup is used to measure the nonlinear refractive index of Patent blue V dye dissolved in distilled water. The material exhibits negative nonlinearity. Optical limiting behavior has been observed for this dye. Further, we have modified the Z-scan setup suitably to realize all-optical AND and OR logic gates.

  1. Spectrally-efficient all-optical OFDM by WSS and AWG.

    PubMed

    Hoxha, J; Morosi, J; Shimizu, S; Martelli, P; Boffi, P; Wada, N; Cincotti, G

    2015-05-01

    We report on the transmission experiment of seven 12.5-GHz spaced all optical-orthogonal frequency division multiplexed (AO-OFDM) subcarriers over a 35-km fiber link, using differential quadrature phase shift keying (DQPSK) modulation and direct detection. The system does not require chromatic dispersion compensation, optical time gating at the receiver (RX) or cyclic prefix (CP), achieving the maximum spectral efficiency. We use a wavelength selective switch (WSS) at the transmitter (TX) to allow subcarrier assignment flexibility and optimal filter shaping; an arrayed waveguide grating (AWG) AO-OFDM demultiplexer is used at the RX, to reduce the system cost and complexity. PMID:25969193

  2. Analysis of all-optical temporal integrator employing phased-shifted DFB-SOA.

    PubMed

    Jia, Xin-Hong; Ji, Xiao-Ling; Xu, Cong; Wang, Zi-Nan; Zhang, Wei-Li

    2014-11-17

    All-optical temporal integrator using phase-shifted distributed-feedback semiconductor optical amplifier (DFB-SOA) is investigated. The influences of system parameters on its energy transmittance and integration error are explored in detail. The numerical analysis shows that, enhanced energy transmittance and integration time window can be simultaneously achieved by increased injected current in the vicinity of lasing threshold. We find that the range of input pulse-width with lower integration error is highly sensitive to the injected optical power, due to gain saturation and induced detuning deviation mechanism. The initial frequency detuning should also be carefully chosen to suppress the integration deviation with ideal waveform output. PMID:25402095

  3. All-optical coherent population trapping with defect spin ensembles in silicon carbide

    PubMed Central

    Zwier, Olger V.; O’Shea, Danny; Onur, Alexander R.; van der Wal, Caspar H.

    2015-01-01

    Divacancy defects in silicon carbide have long-lived electronic spin states and sharp optical transitions. Because of the various polytypes of SiC, hundreds of unique divacancies exist, many with spin properties comparable to the nitrogen-vacancy center in diamond. If ensembles of such spins can be all-optically manipulated, they make compelling candidate systems for quantum-enhanced memory, communication, and sensing applications. We report here direct all-optical addressing of basal plane-oriented divacancy spins in 4H-SiC. By means of magneto-spectroscopy, we fully identify the spin triplet structure of both the ground and the excited state, and use this for tuning of transition dipole moments between particular spin levels. We also identify a role for relaxation via intersystem crossing. Building on these results, we demonstrate coherent population trapping -a key effect for quantum state transfer between spins and photons- for divacancy sub-ensembles along particular crystal axes. These results, combined with the flexibility of SiC polytypes and device processing, put SiC at the forefront of quantum information science in the solid state. PMID:26047132

  4. Design of an All-Optical Network Based on LCoS Technologies

    NASA Astrophysics Data System (ADS)

    Cheng, Yuh-Jiuh; Shiau, Yhi

    2016-06-01

    In this paper, an all-optical network composed of the ROADMs (reconfigurable optical add-drop multiplexer), L2/L3 optical packet switches, and the fiber optical cross-connection for fiber scheduling and measurement based on LCoS (liquid crystal on silicon) technologies is proposed. The L2/L3 optical packet switches are designed with optical output buffers. Only the header of optical packets is converted to electronic signals to control the wavelength of input ports and the packet payloads can be transparently destined to their output ports. An optical output buffer is designed to queue the packets when more than one incoming packet should reach to the same destination output port. For preserving service-packet sequencing and fairness of routing sequence, a priority scheme and a round-robin algorithm are adopted at the optical output buffer. The wavelength of input ports is designed for routing incoming packets using LCoS technologies. Finally, the proposed OFS (optical flow switch) with input buffers can quickly transfer the big data to the output ports and the main purpose of the OFS is to reduce the number of wavelength reflections. The all-optical content delivery network is comprised of the OFSs for a large amount of audio and video data transmissions in the future.

  5. Experimental validation of optical layer performance monitoring using an all-optical network testbed

    NASA Astrophysics Data System (ADS)

    Vukovic, Alex; Savoie, Michel J.; Hua, Heng

    2004-11-01

    Communication transmission systems continue to evolve towards higher data rates, increased wavelength densities, longer transmission distances and more intelligence. Further development of dense wavelength division multiplexing (DWDM) and all-optical networks (AONs) will demand ever-tighter monitoring to assure a specified quality of service (QoS). Traditional monitoring methods have been proven to be insufficient. Higher degree of self-control, intelligence and optimization for functions within next generation networks require new monitoring schemes to be developed and deployed. Both perspective and challenges of performance monitoring, its techniques, requirements and drivers are discussed. It is pointed out that optical layer monitoring is a key enabler for self-control of next generation optical networks. Aside from its real-time feedback and the safeguarding of neighbouring channels, optical performance monitoring ensures the ability to build and control complex network topologies while maintaining an efficiently high QoS. Within an all-optical network testbed environment, key performance monitoring parameters are identified, assessed through real-time proof-of-concept, and proposed for network applications for the safeguarding of neighbouring channels in WDM systems.

  6. High speed all-optical data processing in fast semiconductor and optical fiber based devices

    NASA Astrophysics Data System (ADS)

    Sun, Hongzhi

    Future generations of communication systems demand ultra high speed data processing and switching components. Conventional electrical parts have reached their bottleneck both speed-wise and efficiency-wise. The idea of manipulating high speed data in optical domain is gaining more popularity. In this PhD thesis work, we proposed and demonstrated various schemes of all-optical Boolean logic gate at data rate as high as 80Gb/s by using semiconductor optical amplifier (SOA), SOA Mach-Zehnder interferometer (SOA-MZI), highly nonlinear fiber (HNLF) and optical fiber based components. With the invention of quantum dot (QD) based semiconductor devices, speed limit of all optical data processing has a chance to boost up to 250Gb/s. We proposed and simulated QD-SOA based Boolean functions, and their application such as shift register and pseudorandom bit sequence generation (PRBS). Clock and data recovery of high speed data signals has been simulated and demonstrated by injection lock and phase lock loop techniques in a fiber and SOA ring and an optical-electrical (OE) feedback loop.

  7. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    PubMed Central

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-01-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10−9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation. PMID:27063920

  8. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging.

    PubMed

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-01-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm(3), can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10(-9) m(2)/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation. PMID:27063920

  9. Ultrafast all-optical temporal differentiation in integrated phase-shifted Bragg gratings

    NASA Astrophysics Data System (ADS)

    Rutkowska, Katarzyna A.; Duchesne, David; Strain, Michael J.; Azana, José; Morandotti, Roberto; Sorel, Marc

    2010-12-01

    All-optical communications and data processing exemplifies an important alternative to overcome the speed and bandwidth limitations imposed by electronics. Specifically, practical implementation of analog operations, including optical temporal differentiation, is fundamental for future ultrafast signal processing and computing networks. In addition, the development of fully integrated systems that allow on-single-chip operations is of significant interest. In this work we report the design, fabrication tolerances and first experimental demonstration of an integrated, ultrafast differentiator based on π-phase-shifted Bragg gratings. By using deeply-sidewall-etched Silicon-on-Insulator (SOI) ridged waveguides, first-order optical differentiation has been achieved on sub-millimeters length scales, reaching THz processing speeds. The proposed device has numerous potential applications, including all-optical, analog solving of differential equations (important for virtual modeling of scientific phenomena)1, data processing and analysis2, as well as for the generation of Hermite-Gaussian waveforms (used for arbitrary optical coding and decoding)3.

  10. All-optical coherent population trapping with defect spin ensembles in silicon carbide.

    PubMed

    Zwier, Olger V; O'Shea, Danny; Onur, Alexander R; van der Wal, Caspar H

    2015-01-01

    Divacancy defects in silicon carbide have long-lived electronic spin states and sharp optical transitions. Because of the various polytypes of SiC, hundreds of unique divacancies exist, many with spin properties comparable to the nitrogen-vacancy center in diamond. If ensembles of such spins can be all-optically manipulated, they make compelling candidate systems for quantum-enhanced memory, communication, and sensing applications. We report here direct all-optical addressing of basal plane-oriented divacancy spins in 4H-SiC. By means of magneto-spectroscopy, we fully identify the spin triplet structure of both the ground and the excited state, and use this for tuning of transition dipole moments between particular spin levels. We also identify a role for relaxation via intersystem crossing. Building on these results, we demonstrate coherent population trapping -a key effect for quantum state transfer between spins and photons- for divacancy sub-ensembles along particular crystal axes. These results, combined with the flexibility of SiC polytypes and device processing, put SiC at the forefront of quantum information science in the solid state. PMID:26047132

  11. All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins

    PubMed Central

    Hochbaum, Daniel R.; Zhao, Yongxin; Farhi, Samouil L.; Klapoetke, Nathan; Werley, Christopher A.; Kapoor, Vikrant; Zou, Peng; Kralj, Joel M.; Maclaurin, Dougal; Smedemark-Margulies, Niklas; Saulnier, Jessica L.; Boulting, Gabriella L.; Straub, Christoph; Cho, Yong Ku; Melkonian, Michael; Wong, Gane Ka-Shu; Harrison, D. Jed; Murthy, Venkatesh N.; Sabatini, Bernardo; Boyden, Edward S.; Campbell, Robert E.; Cohen, Adam E.

    2014-01-01

    All-optical electrophysiology—spatially resolved simultaneous optical perturbation and measurement of membrane voltage—would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and 2, which show improved brightness and voltage sensitivity, microsecond response times, and produce no photocurrent. We engineered a novel channelrhodopsin actuator, CheRiff, which shows improved light sensitivity and kinetics, and spectral orthogonality to the QuasArs. A co-expression vector, Optopatch, enabled crosstalk-free genetically targeted all-optical electrophysiology. In cultured neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials in dendritic spines, synaptic transmission, sub-cellular microsecond-timescale details of action potential propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In brain slice, Optopatch induced and reported action potentials and subthreshold events, with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without use of conventional electrodes. PMID:24952910

  12. Ultrasmall all-optical plasmonic switch and its application to superresolution imaging

    NASA Astrophysics Data System (ADS)

    Wu, Hsueh-Yu; Huang, Yen-Ta; Shen, Po-Ting; Lee, Hsuan; Oketani, Ryosuke; Yonemaru, Yasuo; Yamanaka, Masahito; Shoji, Satoru; Lin, Kung-Hsuan; Chang, Chih-Wei; Kawata, Satoshi; Fujita, Katsumasa; Chu, Shi-Wei

    2016-04-01

    Because of their exceptional local-field enhancement and ultrasmall mode volume, plasmonic components can integrate photonics and electronics at nanoscale, and active control of plasmons is the key. However, all-optical modulation of plasmonic response with nanometer mode volume and unity modulation depth is still lacking. Here we show that scattering from a plasmonic nanoparticle, whose volume is smaller than 0.001 μm3, can be optically switched off with less than 100 μW power. Over 80% modulation depth is observed, and shows no degradation after repetitive switching. The spectral bandwidth approaches 100 nm. The underlying mechanism is suggested to be photothermal effects, and the effective single-particle nonlinearity reaches nearly 10‑9 m2/W, which is to our knowledge the largest record of metallic materials to date. As a novel application, the non-bleaching and unlimitedly switchable scattering is used to enhance optical resolution to λ/5 (λ/9 after deconvolution), with 100-fold less intensity requirement compared to similar superresolution techniques. Our work not only opens up a new field of ultrasmall all-optical control based on scattering from a single nanoparticle, but also facilitates superresolution imaging for long-term observation.

  13. All-optical dynamical Casimir effect in a three-dimensional terahertz photonic band gap

    NASA Astrophysics Data System (ADS)

    Hagenmüller, David

    2016-06-01

    We identify an architecture for the observation of all-optical dynamical Casimir effect in realistic experimental conditions. We suggest that by integrating quantum wells in a three-dimensional (3D) photonic band-gap material made out of large-scale (˜200 -μ m ) germanium logs, it is possible to achieve ultrastrong light-matter coupling at terahertz frequencies for the cyclotron transition of a two-dimensional electron gas interacting with long-lived optical modes, in which vacuum Rabi splitting is comparable to the Landau level spacing. When a short, intense electromagnetic transient of duration ˜250 fs and carrying a peak magnetic field ˜5 T is applied to the structure, the cyclotron transition can be suddenly tuned on resonance with a desired photon mode, switching on the light-matter interaction and leading to a Casimir radiation emitted parallel to the quantum well plane. The radiation spectrum consists of sharp peaks with frequencies coinciding with engineered optical modes within the 3D photonic band gap, and its characteristics are extremely robust to the nonradiative damping which can be large in our system. Furthermore, the absence of continuum with associated low-energy excitations for both electromagnetic and electronic quantum states can prevent the rapid absorption of the photon flux which is likely to occur in other proposals for all-optical dynamical Casimir effect.

  14. Nonlinear all-optical switch based on a white-light cavity

    NASA Astrophysics Data System (ADS)

    Li, Na; Xu, Jingping; Song, Ge; Zhu, Chengjie; Xie, Shuangyuan; Yang, Yaping; Zubairy, M. Suhail; Zhu, Shi-Yao

    2016-04-01

    It is well known that there is a bottleneck for nonlinear all-optical switching, namely, the switching power and the switching time cannot be lowered simultaneously. A lower switching power requires a resonator with a high quality (Q ) factor, but leads to a longer switching time. We propose to overcome this bottleneck by replacing the nonlinear cavity in such an all-optical switch by a white-light cavity. This can be done by doping three-level atoms in the ring resonator and applying incoherent pump and coherent driving fields on it. The white-light cavity possesses broadband resonance in a linear region. Therefore, for the incident pulse, a broad range of frequency components can take part in the nonlinear process, and so it requires lower power to achieve switching compared to the conventional ring resonator. On the other hand, the refractive index of a white-light cavity has negative dispersion, leading to a fast group velocity. This results in a shorter time to build up the resonant response, yielding a short switching time.

  15. High-resolution all-optical photoacoustic imaging system for remote interrogation of biological specimens

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin

    2014-05-01

    Conventional photoacoustic imaging (PAI) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target tissue. The resolution of conventional PAI is limited by the sensitivity and bandwidth of the ultrasound transducer. We have developed an all-optical versatile PAI system for characterizing ex vivo and in vivo biological specimens. The system employs noncontact interferometric detection of the acoustic signals that overcomes limitations of conventional PAI. A 532-nm pump laser with a pulse duration of 5 ns excited the PA effect in tissue. Resulting acoustic waves produced surface displacements that were sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a GHz bandwidth. The pump and probe beams were coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam was demodulated using a homodyne interferometer. The detected time-domain signal was time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. Performance was assessed using PA images of ex vivo rabbit lymph node specimens and human tooth samples. A minimum peak surface displacement sensitivity of 0.19 pm was measured. The all-optical PAI (AOPAI) system is well suited for assessment of retinal diseases, caries lesion detection, skin burns, section less histology and pressure or friction ulcers.

  16. Electrical characterization of all-optical helicity-dependent switching in ferromagnetic Hall crosses

    NASA Astrophysics Data System (ADS)

    El Hadri, M. S.; Pirro, P.; Lambert, C.-H.; Bergeard, N.; Petit-Watelot, S.; Hehn, M.; Malinowski, G.; Montaigne, F.; Quessab, Y.; Medapalli, R.; Fullerton, E. E.; Mangin, S.

    2016-02-01

    We present an experimental study of all-optical helicity-dependent switching (AO-HDS) of ferromagnetic Pt/Co/Pt heterostructures with perpendicular magnetic anisotropy. The sample is patterned into a Hall cross and the AO-HDS is measured via the anomalous Hall effect. This all-electrical probing of the magnetization during AO-HDS enables a statistical quantification of the switching ratio for different laser parameters, such as the threshold power to achieve AO-HDS and the exposure time needed to reach complete switching at a given laser power. We find that the AO-HDS is a cumulative process, a certain number of optical pulses is needed to obtain a full and reproducible helicity-dependent switching. The deterministic switching of the ferromagnetic Pt/Co/Pt Hall cross provides a full "opto-spintronic device," where the remanent magnetization can be all-optically and reproducibly written and erased without the need of an external magnetic field.

  17. All-optical logic gates based on cross-phase modulation in an asymmetric coupler

    NASA Astrophysics Data System (ADS)

    Li, Qiliang; Yuan, Hongliang

    2014-05-01

    In this paper we propose an operation of an all-optical logical gate based on an asymmetric nonlinear directional coupler operating with the cross-phase modulation. Two-input OR and XOR gates and a new logical operation based on an asymmetric nonlinear directional coupler, which can be applied to transmission and processing of signals in all-optical systems, are examined. Initially, we evaluate the effect of the pump power on switching. We import a pulse into the nonlinear directional coupler, meanwhile adding a pump light via wavelength division multiplex in order to take advantage of Kerr effect and produce the cross-phase modulation. In this situation, we analyze two possible situations for the two-input logical gate, and draw a switching characteristic curve via Matlab. Finally, we define the truth table and it is clear that OR and XOR logic gates and a new logical operation can be realized by changing the pump power. Next the investigation also indicates that to change the input pulse's phase switching can be realized. In the same way, we define the truth table and it can be observed that different logic gates are realized.

  18. Engineered materials for all-optical helicity-dependent magnetic switching.

    PubMed

    Mangin, S; Gottwald, M; Lambert, C-H; Steil, D; Uhlíř, V; Pang, L; Hehn, M; Alebrand, S; Cinchetti, M; Malinowski, G; Fainman, Y; Aeschlimann, M; Fullerton, E E

    2014-03-01

    The possibility of manipulating magnetic systems without applied magnetic fields have attracted growing attention over the past fifteen years. The low-power manipulation of the magnetization, preferably at ultrashort timescales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization in engineered magnetic materials. We demonstrate that all-optical helicity-dependent switching (AO-HDS) can be observed not only in selected rare earth-transition metal (RE-TM) alloy films but also in a much broader variety of materials, including RE-TM alloys, multilayers and heterostructures. We further show that RE-free Co-Ir-based synthetic ferrimagnetic heterostructures designed to mimic the magnetic properties of RE-TM alloys also exhibit AO-HDS. These results challenge present theories of AO-HDS and provide a pathway to engineering materials for future applications based on all-optical control of magnetic order. PMID:24531398

  19. New alternative approach to all-optical flip-flop with nonlinear material

    NASA Astrophysics Data System (ADS)

    Giri, Dibyendu; Das, Partha Pratima

    2010-07-01

    Due to its inherent parallelism and tremendous operational speed, optical signal is the most suitable for data processing and digital communication in various fields. Conventional electronic and opto-electronic systems are unable to fulfill this arena, because of their low speed and time delay. In the case of pure electronic flip-flop, when a switch is turned ON, there is notable propagation delay on the order of nanoseconds. For an opto-electronic flip-flop although the propagation delay time is much less than that of an electronic flip-flop (about 10 to 100 times less), there are many disadvantages. Some of these disadvantages are delay of response time due to the use of spatial light modulators, an O/E converter that does not operate at all frequencies or wavelengths, and the unavailability of such materials. An optical input encoding methodology is proposed for the performance of all-optical flip-flop operations possible for two inputs. These operations were conducted in all-optical mode and are parallel in nature. All the operations are treated with proper exploitation of some nonlinear materials.

  20. All-optical electrophysiology in mammalian neurons using engineered microbial rhodopsins.

    PubMed

    Hochbaum, Daniel R; Zhao, Yongxin; Farhi, Samouil L; Klapoetke, Nathan; Werley, Christopher A; Kapoor, Vikrant; Zou, Peng; Kralj, Joel M; Maclaurin, Dougal; Smedemark-Margulies, Niklas; Saulnier, Jessica L; Boulting, Gabriella L; Straub, Christoph; Cho, Yong Ku; Melkonian, Michael; Wong, Gane Ka-Shu; Harrison, D Jed; Murthy, Venkatesh N; Sabatini, Bernardo L; Boyden, Edward S; Campbell, Robert E; Cohen, Adam E

    2014-08-01

    All-optical electrophysiology-spatially resolved simultaneous optical perturbation and measurement of membrane voltage-would open new vistas in neuroscience research. We evolved two archaerhodopsin-based voltage indicators, QuasAr1 and QuasAr2, which show improved brightness and voltage sensitivity, have microsecond response times and produce no photocurrent. We engineered a channelrhodopsin actuator, CheRiff, which shows high light sensitivity and rapid kinetics and is spectrally orthogonal to the QuasArs. A coexpression vector, Optopatch, enabled cross-talk-free genetically targeted all-optical electrophysiology. In cultured rat neurons, we combined Optopatch with patterned optical excitation to probe back-propagating action potentials (APs) in dendritic spines, synaptic transmission, subcellular microsecond-timescale details of AP propagation, and simultaneous firing of many neurons in a network. Optopatch measurements revealed homeostatic tuning of intrinsic excitability in human stem cell-derived neurons. In rat brain slices, Optopatch induced and reported APs and subthreshold events with high signal-to-noise ratios. The Optopatch platform enables high-throughput, spatially resolved electrophysiology without the use of conventional electrodes. PMID:24952910

  1. Direct conversion of h-BN into c-BN and formation of epitaxial c-BN/diamond heterostructures

    NASA Astrophysics Data System (ADS)

    Narayan, Jagdish; Bhaumik, Anagh; Xu, Weizong

    2016-05-01

    We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800 K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and single-crystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications.

  2. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system.

    PubMed

    Ohtomo, Yoko; Ijiri, Akira; Ikegawa, Yojiro; Tsutsumi, Masazumi; Imachi, Hiroyuki; Uramoto, Go-Ichiro; Hoshino, Tatsuhiko; Morono, Yuki; Sakai, Sanae; Saito, Yumi; Tanikawa, Wataru; Hirose, Takehiro; Inagaki, Fumio

    2013-01-01

    Geological CO2 sequestration in unmineable subsurface oil/gas fields and coal formations has been proposed as a means of reducing anthropogenic greenhouse gasses in the atmosphere. However, the feasibility of injecting CO2 into subsurface depends upon a variety of geological and economic conditions, and the ecological consequences are largely unpredictable. In this study, we developed a new flow-through-type reactor system to examine potential geophysical, geochemical and microbiological impacts associated with CO2 injection by simulating in-situ pressure (0-100 MPa) and temperature (0-70°C) conditions. Using the reactor system, anaerobic artificial fluid and CO2 (flow rate: 0.002 and 0.00001 ml/min, respectively) were continuously supplemented into a column comprised of bituminous coal and sand under a pore pressure of 40 MPa (confined pressure: 41 MPa) at 40°C for 56 days. 16S rRNA gene analysis of the bacterial components showed distinct spatial separation of the predominant taxa in the coal and sand over the course of the experiment. Cultivation experiments using sub-sampled fluids revealed that some microbes survived, or were metabolically active, under CO2-rich conditions. However, no methanogens were activated during the experiment, even though hydrogenotrophic and methylotrophic methanogens were obtained from conventional batch-type cultivation at 20°C. During the reactor experiment, the acetate and methanol concentration in the fluids increased while the δ(13)Cacetate, H2 and CO2 concentrations decreased, indicating the occurrence of homo-acetogenesis. 16S rRNA genes of homo-acetogenic spore-forming bacteria related to the genus Sporomusa were consistently detected from the sandstone after the reactor experiment. Our results suggest that the injection of CO2 into a natural coal-sand formation preferentially stimulates homo-acetogenesis rather than methanogenesis, and that this process is accompanied by biogenic CO2 conversion to acetate. PMID:24348470

  3. Conversion of alpha-helices into beta-sheets features in the formation of the scrapie prion proteins.

    PubMed Central

    Pan, K M; Baldwin, M; Nguyen, J; Gasset, M; Serban, A; Groth, D; Mehlhorn, I; Huang, Z; Fletterick, R J; Cohen, F E

    1993-01-01

    Prions are composed largely, if not entirely, of prion protein (PrPSc in the case of scrapie). Although the formation of PrPSc from the cellular prion protein (PrPC) is a post-translational process, no candidate chemical modification was identified, suggesting that a conformational change features in PrPSc synthesis. To assess this possibility, we purified both PrPC and PrPSc by using nondenaturing procedures and determined the secondary structure of each. Fourier-transform infrared (FTIR) spectroscopy demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), findings that were confirmed by circular dichroism measurements. In contrast, the beta-sheet content of PrPSc was 43% and the alpha-helix 30% as measured by FTIR. As determined in earlier studies, N-terminally truncated PrPSc derived by limited proteolysis, designated PrP 27-30, has an even higher beta-sheet content (54%) and a lower alpha-helix content (21%). Neither PrPC nor PrPSc formed aggregates detectable by electron microscopy, while PrP 27-30 polymerized into rod-shaped amyloids. While the foregoing findings argue that the conversion of alpha-helices into beta-sheets underlies the formation of PrPSc, we cannot eliminate the possibility that an undetected chemical modification of a small fraction of PrPSc initiates this process. Since PrPSc seems to be the only component of the "infectious" prion particle, it is likely that this conformational transition is a fundamental event in the propagation of prions. Images Fig. 1 Fig. 4 PMID:7902575

  4. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system

    PubMed Central

    Ohtomo, Yoko; Ijiri, Akira; Ikegawa, Yojiro; Tsutsumi, Masazumi; Imachi, Hiroyuki; Uramoto, Go-Ichiro; Hoshino, Tatsuhiko; Morono, Yuki; Sakai, Sanae; Saito, Yumi; Tanikawa, Wataru; Hirose, Takehiro; Inagaki, Fumio

    2013-01-01

    Geological CO2 sequestration in unmineable subsurface oil/gas fields and coal formations has been proposed as a means of reducing anthropogenic greenhouse gasses in the atmosphere. However, the feasibility of injecting CO2 into subsurface depends upon a variety of geological and economic conditions, and the ecological consequences are largely unpredictable. In this study, we developed a new flow-through-type reactor system to examine potential geophysical, geochemical and microbiological impacts associated with CO2 injection by simulating in-situ pressure (0–100 MPa) and temperature (0–70°C) conditions. Using the reactor system, anaerobic artificial fluid and CO2 (flow rate: 0.002 and 0.00001 ml/min, respectively) were continuously supplemented into a column comprised of bituminous coal and sand under a pore pressure of 40 MPa (confined pressure: 41 MPa) at 40°C for 56 days. 16S rRNA gene analysis of the bacterial components showed distinct spatial separation of the predominant taxa in the coal and sand over the course of the experiment. Cultivation experiments using sub-sampled fluids revealed that some microbes survived, or were metabolically active, under CO2-rich conditions. However, no methanogens were activated during the experiment, even though hydrogenotrophic and methylotrophic methanogens were obtained from conventional batch-type cultivation at 20°C. During the reactor experiment, the acetate and methanol concentration in the fluids increased while the δ13Cacetate, H2 and CO2 concentrations decreased, indicating the occurrence of homo-acetogenesis. 16S rRNA genes of homo-acetogenic spore-forming bacteria related to the genus Sporomusa were consistently detected from the sandstone after the reactor experiment. Our results suggest that the injection of CO2 into a natural coal-sand formation preferentially stimulates homo-acetogenesis rather than methanogenesis, and that this process is accompanied by biogenic CO2 conversion to acetate. PMID

  5. Biological CO2 conversion to acetate in subsurface coal-sand formation using a high-pressure reactor system

    NASA Astrophysics Data System (ADS)

    Ohtomo, Y.; Ijiri, A.; Ikegawa, Y.; Tsutsumi, M.; Imachi, H.; Uramoto, G.; Hoshino, T.; Morono, Y.; Tanikawa, W.; Hirose, T.; Inagaki, F.

    2013-12-01

    belonged to a methylotrophic methanogen within the genus Methanosarcina. For the acetate-fed culture, no cell proliferation and methane-production were observed after two-years incubation. During the injection of CO2 and fluid, increase of dissolved CH4 concentration was observed, of which δ13CCH4 were constantly similar to those of the absorbed coal-bed methane (δ13CCBM, ~70‰), suggesting the enhanced gas recovery with fluid flow. The output volume of CO2 (ΣCO2out, 22.1 to 125.6 mM) was smaller than initial concentration (ΣCO2in, 138.38 mM), which can be explained by either adsorption on coal, formation of carbonate minerals, or microbial consumption. Increase of acetate concentration in the fluids was also observed, whereas δ13Cacetate depleted during experiment. Considering with the decrease of additive H2, it is most likely that homo-acetogenesis would occur during experiments, which is consistent with detection of Sporomusa-related 16S rRNA genes, homo-acetogenic bacterium, in cloning analysis of sandstone after experiment. Decrease of formate concentrations and increase of δ13Cformate indicate bacterial consumption of formate and isotopic fractionation. Our results suggest that CO2 injection to natural coal-sand formation stimulates homo-acetogenesis rather than methanogenesis, accompanied by biogenic CO2 conversion to acetate.

  6. Complete all-optical processing polarization-based binary logic gates and optical processors.

    PubMed

    Zaghloul, Y A; Zaghloul, A R M

    2006-10-16

    We present a complete all-optical-processing polarization-based binary-logic system, by which any logic gate or processor can be implemented. Following the new polarization-based logic presented in [Opt. Express 14, 7253 (2006)], we develop a new parallel processing technique that allows for the creation of all-optical-processing gates that produce a unique output either logic 1 or 0 only once in a truth table, and those that do not. This representation allows for the implementation of simple unforced OR, AND, XOR, XNOR, inverter, and more importantly NAND and NOR gates that can be used independently to represent any Boolean expression or function. In addition, the concept of a generalized gate is presented which opens the door for reconfigurable optical processors and programmable optical logic gates. Furthermore, the new design is completely compatible with the old one presented in [Opt. Express 14, 7253 (2006)], and with current semiconductor based devices. The gates can be cascaded, where the information is always on the laser beam. The polarization of the beam, and not its intensity, carries the information. The new methodology allows for the creation of multiple-input-multiple-output processors that implement, by itself, any Boolean function, such as specialized or non-specialized microprocessors. Three all-optical architectures are presented: orthoparallel optical logic architecture for all known and unknown binary gates, singlebranch architecture for only XOR and XNOR gates, and the railroad (RR) architecture for polarization optical processors (POP). All the control inputs are applied simultaneously leading to a single time lag which leads to a very-fast and glitch-immune POP. A simple and easy-to-follow step-by-step algorithm is provided for the POP, and design reduction methodologies are briefly discussed. The algorithm lends itself systematically to software programming and computer-assisted design. As examples, designs of all binary gates, multiple

  7. Interaction-free all-optical switching via the quantum Zeno effect

    NASA Astrophysics Data System (ADS)

    Huang, Yu-Ping; Altepeter, Joseph B.; Kumar, Prem

    2010-12-01

    We propose an interaction-free scheme for all-optical switching which does not rely on the physical coupling between signal and control waves. The interaction-free nature of the scheme allows it to overcome the fundamental photon-loss limit imposed by the signal-pump coupling. The same phenomenon protects photonic-signal states from decoherence, making devices based on this scheme suitable for quantum applications. Focusing on χ(2) waveguides, we provide device designs for traveling-wave and Fabry-Perot switches. In both designs, the performance is optimal when the signal switching is induced by coherent dynamical evolution. In contrast, when the switching is induced by a rapid dissipation channel, it is less efficient.

  8. All-Optical Sensing of the Components of the Internal Local Electric Field in Proteins

    PubMed Central

    Drobizhev, M.; Scott, J. N.; Callis, P. R.; Rebane, A.

    2014-01-01

    Here, we present a new all-optical method of interrogation of the internal electric field vector inside proteins. The method is based on experimental evaluation of the permanent dipole moment change upon excitation and the pure electronic transition frequency of a fluorophore embedded in a protein matrix. The permanent dipole moment change can be obtained from two-photon absorption measurements. In addition, permanent dipole moment change, tensor of polarizability change, and transition frequency for the free chromophore should be calculated quantum–mechanically. This allows obtaining the components of the electric field by considering the second-order Stark shift. We use the fluorescent protein mCherry as an example to demonstrate the applicability of the method. PMID:25419440

  9. All-Optical Sensing of the Components of the Internal Local Electric Field in Proteins.

    PubMed

    Drobizhev, M; Scott, J N; Callis, P R; Rebane, A

    2012-10-01

    Here, we present a new all-optical method of interrogation of the internal electric field vector inside proteins. The method is based on experimental evaluation of the permanent dipole moment change upon excitation and the pure electronic transition frequency of a fluorophore embedded in a protein matrix. The permanent dipole moment change can be obtained from two-photon absorption measurements. In addition, permanent dipole moment change, tensor of polarizability change, and transition frequency for the free chromophore should be calculated quantum-mechanically. This allows obtaining the components of the electric field by considering the second-order Stark shift. We use the fluorescent protein mCherry as an example to demonstrate the applicability of the method. PMID:25419440

  10. High-speed all-optical logic inverter based on stimulated Raman scattering in silicon nanocrystal.

    PubMed

    Sen, Mrinal; Das, Mukul K

    2015-11-01

    In this paper, we propose a new device architecture for an all-optical logic inverter (NOT gate), which is cascadable with a similar device. The inverter is based on stimulated Raman scattering in silicon nanocrystal waveguides, which are embedded in a silicon photonic crystal structure. The Raman response function of silicon nanocrystal is evaluated to explore the transfer characteristic of the inverter. A maximum product criterion for the noise margin is taken to analyze the cascadability of the inverter. The time domain response of the inverter, which explores successful inversion operation at 100 Gb/s, is analyzed. Propagation delay of the inverter is on the order of 5 ps, which is less than the delay in most of the electronic logic families as of today. Overall dimension of the device is around 755  μm ×15  μm, which ensures integration compatibility with the matured silicon industry. PMID:26560565

  11. All-optical cascaded laser wakefield accelerator using ionization-induced injection.

    PubMed

    Liu, J S; Xia, C Q; Wang, W T; Lu, H Y; Wang, Ch; Deng, A H; Li, W T; Zhang, H; Liang, X Y; Leng, Y X; Lu, X M; Wang, C; Wang, J Z; Nakajima, K; Li, R X; Xu, Z Z

    2011-07-15

    We report on near-GeV electron beam generation from an all-optical cascaded laser wakefield accelerator (LWFA). Electron injection and acceleration are successfully separated and controlled in different LWFA stages by employing two gas cells filled with a He/O2 mixture and pure He gas, respectively. Electrons with a Maxwellian spectrum, generated from the first LWFA assisted by ionization-induced injection, were seeded into the second LWFA with a 3-mm-thick gas cell and accelerated to be a 0.8-GeV quasimonoenergetic electron beam, corresponding to an acceleration gradient of 187  GV/m. The demonstrated scheme paves the way towards the multi-GeV laser accelerators. PMID:21838367

  12. Noncontact broadband all-optical photoacoustic microscopy based on a low-coherence interferometer

    NASA Astrophysics Data System (ADS)

    Chen, Zhongjiang; Yang, Sihua; Wang, Yi; Xing, Da

    2015-01-01

    We developed and fabricated a noncontact broadband all-optical photoacoustic microscopy (BD-AO-PAM) with a microchip laser and an all-fiber low coherence interferometer. Currently, the available detection bandwidth of the BD-AO-PAM is 67 MHz, and the lateral resolution measured by carbon fibers reaches 11 μm. Furthermore, the imaging capability of the BD-AO-PAM was testified by imaging hairs embedded in scattering gel and in vivo blood vessels of a mouse ear. The experimental results demonstrate that the BD-AO-PAM can image the tissues with high spatial resolution in vivo, which can be used as portable noncontact PAM for biomedical applications.

  13. All-optical measurement of elastic constants in nematic liquid crystals.

    PubMed

    Klus, Bartłomiej; Laudyn, Urszula A; Karpierz, Mirosław A; Sahraoui, Bouchta

    2014-12-01

    In this article we present a new all-optical method to measure elastic constants connected with twist and bend deformations. The method is based on the optical Freedericksz threshold effect induced by the linearly polarized electro-magnetic wave. In the experiment elastic constants are measured of commonly used liquid crystals 6CHBT and E7 and two new nematic mixtures with low birefringence. The proposed method is neither very sensitive on the variation of cell thickness, beam waist or the power of a light beam nor does it need any special design of a liquid crystal cell. The experimental results are in good agreement with the values obtain by other methods based on an electro-optical effect. PMID:25606956

  14. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer

    NASA Astrophysics Data System (ADS)

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-04-01

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems.

  15. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer.

    PubMed

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-04-12

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems. PMID:26976565

  16. All-optical cooling of K39 to Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Salomon, G.; Fouché, L.; Lepoutre, S.; Aspect, A.; Bourdel, T.

    2014-09-01

    We report the all-optical production of Bose-Einstein condensates (BEC) of K39 atoms. We directly load 3×107 atoms in a large volume optical dipole trap from gray molasses on the D1 transition. We then apply a small magnetic quadrupole field to polarize the sample before transferring the atoms in a tightly confining optical trap. Evaporative cooling is finally performed close to a Feshbach resonance to enhance the scattering length. Our setup allows one to cross the BEC threshold with 3×105 atoms every 7 s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the one-dimensional to three-dimensional crossover.

  17. All-optical transistor using a photonic-crystal cavity with an active Raman gain medium

    NASA Astrophysics Data System (ADS)

    Arkhipkin, V. G.; Myslivets, S. A.

    2013-09-01

    We propose a design of an all-optical transistor based on a one-dimensional photonic-crystal cavity doped with a four-level N-type active Raman gain medium. The calculated results show that in a photonic-crystal cavity of this kind transmission and reflection of the probe (Raman) beam are strongly dependent on the optical switching power. Transmission and reflection of the probe beam can be greatly amplified or attenuated. Therefore the optical switching field can serve as a gate field of the transistor to effectively control propagation of the weak probe field. It is shown that the group velocity of the probe pulse can be controlled in the range from subluminal (slow light) to superluminal (fast light).

  18. A new optical neuron device for all-optical neural networks

    NASA Astrophysics Data System (ADS)

    Akiyama, Koji; Takimoto, Akio; Miyauchi, Michihiro; Kuratomi, Yasunori; Asayama, Junko; Ogawa, Hisahito

    1991-12-01

    A new optical neuron device has been developed. The device can perform both summation and thresholding operations in optics, and consists of a PIN a Si:H photoreceptor, aluminum neuron electrodes and a ferroelectric liquid crystal light modulator. The a-Si:H photoreceptor shows characteristics of an ideal quantum efficiency and a good linearity. The optical neuron device exhibits a response time of about 30 microns for incident light power of 9 microW and a contrast ratio of 300:1. Using this neuron device, a lenslet array and a memory mask, an all-optical neural network has been constructed. The network demonstrates an associate memory function on purely optical parallel processing without any help from electric computation.

  19. Tuning all-Optical Analog to Electromagnetically Induced Transparency in nanobeam cavities using nanoelectromechanical system

    PubMed Central

    Shi, Peng; Zhou, Guangya; deng, Jie; Tian, Feng; Chau, Fook Siong

    2015-01-01

    We report the observations of all-optical electromagnetically induced transparency in nanostructures using waveguide side-coupled with photonic crystal nanobeam cavities, which has measured linewidths much narrower than individual resonances. The quality factor of transparency resonance can be 30 times larger than those of measured individual resonances. When the gap between cavity and waveguide is reduced to 10 nm, the bandwidth of destructive interference region can reach 10 nm while the width of transparency resonance is 0.3 nm. Subsequently, a comb-drive actuator is introduced to tune the line shape of the transparency resonance. The width of the peak is reduced to 15 pm and the resulting quality factor exceeds 105. PMID:26415907

  20. High efficiency all-optical diode based on photonic crystal waveguide

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Liu, Yun-Feng; Li, Shu-Jing; He, Xing-Dao

    2016-06-01

    A high efficiency all-optical diode based on photonic crystal (PC) waveguide has been proposed and numerically investigated by finite-difference time-domain (FDTD) method. The structure is asymmetrically coupled by a Fano cavity containing nonlinear Kerr medium and a F-P cavity in PC waveguide. Because of interference between two cavities, Fano peak and F-P peak can both appear in transmission spectra. Working wavelength is set between the two peaks and approaching to Fano peak. For forward launch with suitable light intensity, nonlinear Kerr effect of micro-cavity can be excited. It would result in red shift of Fano peak and achieving forward transmission. But due to the asymmetric design, backward launch need stronger incidence light to excite Kerr effect. This design has many advantages, including high maximum transmittance (>90%), high transmittance contrast ratio, low power threshold, short response time (picosecond level), ease of integration.

  1. Architectures and algorithms for all-optical 3D signal processing

    NASA Astrophysics Data System (ADS)

    Giglmayr, Josef

    1999-07-01

    All-optical signal processing by >= 2D lightwave circuits (LCs) is (i) aimed to allow the (later) inclusion of the frequency domain and is (ii) subject to photonic integration and thus the architectural and algorithmic framework has to be prepared carefully. Much work has been done in >= 2D algebraic system theory/modern control theory which has been applied in the electronic field of signal and image processing. For the application to modeling, analysis and design of the proposed 3D lightwave circuits (LCs) some elements are needed to describe and evalute the system efficiency as the number of system states of 3D LCs increases dramatically with regard to the number of i/o. Several problems, arising throughput such an attempt, are made transparent and solutions are proposed.

  2. Deterministic character of all-optical magnetization switching in GdFe-based ferrimagnetic alloys

    NASA Astrophysics Data System (ADS)

    Le Guyader, L.; El Moussaoui, S.; Buzzi, M.; Savoini, M.; Tsukamoto, A.; Itoh, A.; Kirilyuk, A.; Rasing, Th.; Nolting, F.; Kimel, A. V.

    2016-04-01

    Using photoemission electron microscopy with x-ray magnetic circular dichroism as a contrast mechanism, new insights into the all-optical magnetization switching (AOS) phenomenon in GdFe-based rare-earth transition-metal ferrimagnetic alloys are provided. From a sequence of static images taken after single linearly polarized laser pulse excitation, the repeatability of AOS can be quantified with a correlation coefficient. It is found that low coercivity enables thermally activated domain-wall motion, limiting in turn the repeatability of the switching. Time-resolved measurements of the magnetization dynamics reveal that while AOS occurs below and above the magnetization compensation temperature TM, it is not observed in GdFe samples where TM is absent. Finally, AOS is experimentally demonstrated against an applied magnetic field of up to 180 mT.

  3. Broadband all-optical modulation in hydrogenated-amorphous silicon waveguides.

    PubMed

    Narayanan, Karthik; Elshaari, Ali W; Preble, Stefan F

    2010-05-10

    We demonstrate broadband all-optical modulation in low loss hydrogenated-amorphous silicon (a-Si:H) waveguides. Significant modulation (approximately 3 dB) occurs with a device of only 15 microm without the need for cavity interference effects in stark contrast to an identical crystalline silicon waveguide. We attribute the enhanced modulation to the significantly larger free-carrier absorption effect of a-Si:H, estimated here to be alpha = 1.6310(-16)N cm(-1). In addition, we measured the modulation time to be only tau(c) approximately 400 ps, which is comparable to the recombination rate measured in sub-micron crystalline silicon waveguides, illustrating the strong dominance of surface recombination in similar sized (460 nm x 250 nm) a-Si:H waveguides. Consequently, a-Si:H could serve as a high performance platform for backend integrated CMOS photonics. PMID:20588830

  4. Spin centres in SiC for all-optical nanoscale quantum sensing under ambient conditions

    NASA Astrophysics Data System (ADS)

    Anisimov, A. N.; Babunts, R. A.; Kidalov, S. V.; Mokhov, E. N.; Soltamov, V. A.; Baranov, P. G.

    2016-07-01

    Level anticrossing (LAC) spectroscopy was demonstrated on a family of uniaxially oriented spin colour centres with S = 3/2 in the ground and excited states in hexagonal 4H-, 6H- and rhombic 15R- SiC polytypes. It was shown that these centres exhibit unique characteristics such as optical spin alignment up to the temperatures of 250 ◦C. A sharp variation of the IR photoluminescence intensity in the vicinity of LAC with the record contrast was observed, which can be used for a purely all-optical sensing of the magnetic field and temperature without applying radiofrequency field. A distinctive feature of the LAC signal is weak dependence on the direction of the magnetic field that allows one to monitor the LAC signals in the nonoriented systems, such as powder of SiC nanocrystals.

  5. Remoted all optical instantaneous frequency measurement system using nonlinear mixing in highly nonlinear optical fiber.

    PubMed

    Bui, Lam Anh; Mitchell, Arnan

    2013-04-01

    A novel remoted instantaneous frequency measurement system using all optical mixing is demonstrated. This system copies an input intensity modulated optical carrier using four wave mixing, delays this copy and then mixes it with the original signal, to produce an output idler tone. The intensity of this output can be used to determine the RF frequency of the input signal. This system is inherently broadband and can be easily scaled beyond 40 GHz while maintaining a DC output which greatly simplifies receiving electronics. The remoted configuration isolates the sensitive and expensive receiver hardware from the signal sources and importantly allows the system to be added to existing microwave photonic implementations without modification of the transmission module. PMID:23571944

  6. Nanoscale Confinement of All-Optical Magnetic Switching in TbFeCo

    NASA Astrophysics Data System (ADS)

    Liu, Tianmin; Wang, Tianhan; Reid, Alexander; Savoini, Matteo; Wu, Xiaofei; Konene, Benny; Granitzka, Patrick; Graves, Catherine; Higley, Daniel; Chen, Zhao; Razinskas, Gary; Hantschmann, Markus; Scherz, Andreas; Stohr, Joachim; Tsukamoto, Arata; Hecht, Bert; Kimel, Alexey; Kirilyuk, Andrei; Rasing, Theo; Durr, Hermann; Durr/Stohr Team; Theo Rasing Team; Arata Tsukamoto Team; Bert Hecht Team

    Gold two-wire antennas structures are placed upon the surface of the all-optical switching film TbFeCo. They resonate with the optical field and create a field enhancement in its vicinity, which is used to confine the area where optical switching can occur. It is demonstrated that single femtosecond optical laser pulses can reverse magnetization in a controllable fashion by such confinement. The magnetic states are imaged using resonant X-ray holography and magnetic circular dichroism. The results not only show the feasibility of controllable switching with antenna assistance but also demonstrate the highly inhomogeneous nature of the switching process, which is attributed to the material's heterogeneity. Research is supported by U.S. DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division.

  7. Numerical simulation for all-optical Thomson scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Tan, Fang; Zhu, Bin; Han, Dan; Xin, Jian-Ting; Zhao, Zong-Qing; Cao, Lei-Feng; Gu, Yu-Qiu; Zhang, Bao-Han

    2014-03-01

    Energy spectra, angular distributions, and temporal profiles of the photons produced by an all-optical Thomson scattering X-ray source are explored through numerical simulations based on the parameters of the SILEX-I laser system (800 nm, 30 fs, 300 TW) and the previous wakefield acceleration experimental results. The simulation results show that X-ray pulses with a duration of 30 fs and an emission angle of 50 mrad can be produced from such a source. Using the optimized electron parameters, X-ray pulses with better directivity and narrower energy spectra can be obtained. Besides the electron parameters, the laser parameters such as the wavelength, pulse duration, and spot size also affect the X-ray yield, the angular distribution, and the maximum photon energy, except the X-ray pulse duration which is slightly changed for the case of ultrafast laser—electron interaction.

  8. Ultralow-power all-optical tunable double plasmon-induced transparencies in nonlinear metamaterials

    SciTech Connect

    Zhu, Yu; Yang, Hong; Hu, Xiaoyong E-mail: qhgong@pku.edu.cn; Gong, Qihuang E-mail: qhgong@pku.edu.cn

    2014-05-26

    An all-optical tunable double plasmon-induced transparency is realized in a photonic metamaterial coated on the surface of a nanocomposite layer made of polycrystalline indium-tin oxide doped with gold nanoparticles. The local-field effect, quantum confinement effect, and hot-electron injection ensure a large optical nonlinearity for the nanocomposite. A shift of 120 nm in the central wavelength of transparency windows is reached under excitation with a weak pump laser with an intensity of 21 kW/cm{sup 2}. Compared with previous reports, the threshold pump intensity is reduced by five orders of magnitude, while an ultrafast response time of 34.9 ps is maintained.

  9. Banded all-optical OFDM super-channels with low-bandwidth receivers.

    PubMed

    Song, Binhuang; Zhu, Chen; Corcoran, Bill; Zhuang, Leimeng; Lowery, Arthur James

    2016-08-01

    We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%. PMID:27505764

  10. All optical switching in a photochromic dye-doped biopolymeric matrix

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Malak, Anna; Sikora, Joanna; Miniewicz, Andrzej; Sahraoui, Bouchta; Rau, Ileana; Kajzar, François

    2011-09-01

    All optical switching has been studied using the Optical Kerr Effect (OKE) configuration in a biopolymer matrix containing a photochromic molecule. The biopolymer system consisted of a deoxyribonucleic acid blended with cationic surfactant molecule cetyltrimethyl-ammonium chloride suitable for optical quality thin film fabrication. The excitation beams inducing birefringence were delivered from a continuous wave laser at 473 and chopped using a variable frequency chopper. Additionally auxiliary nanosecond pulses coming from Nd:YAG laser were used. The birefringence was instantaneously monitored by a weak non-absorbed light from a cw He-Ne laser working at 632.8 nm under crossed polarizer system. Excellent switching times in the range of microseconds and full reversibility of the studied processes have been observed.ïýïýïý

  11. Nanoscale sub-100 picosecond all-optical magnetization switching in GdFeCo microstructures.

    PubMed

    Le Guyader, L; Savoini, M; El Moussaoui, S; Buzzi, M; Tsukamoto, A; Itoh, A; Kirilyuk, A; Rasing, T; Kimel, A V; Nolting, F

    2015-01-01

    Ultrafast magnetization reversal driven by femtosecond laser pulses has been shown to be a promising way to write information. Seeking to improve the recording density has raised intriguing fundamental questions about the feasibility of combining ultrafast temporal resolution with sub-wavelength spatial resolution for magnetic recording. Here we report on the experimental demonstration of nanoscale sub-100 ps all-optical magnetization switching, providing a path to sub-wavelength magnetic recording. Using computational methods, we reveal the feasibility of nanoscale magnetic switching even for an unfocused laser pulse. This effect is achieved by structuring the sample such that the laser pulse, via both refraction and interference, focuses onto a localized region of the structure, the position of which can be controlled by the structural design. Time-resolved photo-emission electron microscopy studies reveal that nanoscale magnetic switching employing such focusing can be pushed to the sub-100 ps regime. PMID:25581133

  12. Femtosecond all-optical synchronization of an X-ray free-electron laser

    SciTech Connect

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; Mazza, T.; Meyer, M.; Pfeiffer, S.; Prędki, P.; Schefer, S.; Schmidt, C.; Wegner, U.; Schlarb, H.; Cavalieri, A. L.

    2015-01-20

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

  13. Femtosecond all-optical synchronization of an X-ray free-electron laser

    DOE PAGESBeta

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; et al

    2015-01-20

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarilymore » by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.« less

  14. Simple nonlinear interferometer-based all-optical thresholder and its applications for optical CDMA.

    PubMed

    Kravtsov, Konstantin; Prucnal, Paul R; Bubnov, Mikhail M

    2007-10-01

    We present an experimental demonstration of an ultrafast all-optical thresholder based on a nonlinear Sagnac interferometer. The proposed design is intended for operation at very small nonlinear phase shifts. Therefore, it requires an in-loop nonlinearity lower than for the classical nonlinear loop mirror scheme. Only 15 meters of conventional (non-holey) silica-based fiber is used as a nonlinear element. The proposed thresholder is polarization insensitive and is good for multi-wavelength operation, meeting all the requirements for autocorrelation detection in various optical CDMA communication systems. The observed cubic transfer function is superior to the quadratic transfer function of second harmonic generation-based thresholders. PMID:19550579

  15. Study of the all-optical high-speed OFDM transmission system based on MAMSK modulation

    NASA Astrophysics Data System (ADS)

    Shang, Tao; Sun, Jinkui; Li, Yang; Wang, Xin

    2012-12-01

    In this paper, an all-optical orthogonal frequency division multiplexing (OOFDM) system based on the multi-amplitude minimum shift keying (MAMSK) modulation is proposed. A scheme to realize MAMSK is designed, and the influence of modulation index on the performance of MAMSK is discussed. Numerical simulations and analysis are performed, and the comparison between the MAMSK-OOFDM and the MAMSK-WDM system is made. The lowest value of the BER of MAMSK-OOFDM is 3.98 × 10-6, while that of MAMSK-WDM is 7.94 × 10-4 when the input power is 0.8 mw and dispersion is completely compensated. The results show that, for its multi-level amplitude and excellent spectrum efficiency, MAMSK-OOFDM can greatly mitigate the effects caused by dispersive and nonlinear phenomena, and it can also effectively improve the capacity of the system.

  16. Multiport InP monolithically integrated all-optical wavelength router.

    PubMed

    Zheng, Xiu; Raz, Oded; Calabretta, Nicola; Zhao, Dan; Lu, Rongguo; Liu, Yong

    2016-08-15

    An indium phosphide-based monolithically integrated wavelength router is demonstrated in this Letter. The wavelength router has four input ports and four output ports, which integrate four wavelength converters and a 4×4 arrayed-waveguide grating router. Each wavelength converter is achieved based on cross-gain modulation and cross-phase modulation effects in a semiconductor optical amplifier. Error-free wavelength switching for a non-return-to-zero 231-1 ps eudorandom binary sequence at 40 Gb/s data rate is performed. Both 1×4 and 3×1 all-optical routing functions of this chip are demonstrated for the first time with power penalties as low as 3.2 dB. PMID:27519116

  17. All-optical 20 Gbit/s NRZ-DPSK demodulation and clock recovery

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Zhang, Xinliang; Dong, Jianji; Yu, Yu; Huang, Xi

    2008-11-01

    All-optical clock recovery (CR) from 20-Gbit/s nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) signal is demonstrated experimentally by using Polarization-Maintaining Fiber Loop Mirror Filter and semiconductor optical amplifier (SOA) fiber ring laser. Only by adjusting polarization controller (PC), NRZ-DPSK signal were conveniently and fast converted to pseudo return-to-zero (PRZ) signal via PMF-LMF. Then the PRZ signal is injected into the SOA fiber laser for CR. The recovered clock signals with the extinction ratio of 10 dB and the root-mean-square timing jitter of 850 fs is achieved under 231-1 pseudorandom binary sequence NRZ-DPSK signals measurement.

  18. All-optical switches, unidirectional flow, and logic gates with discrete solitons in waveguide arrays.

    PubMed

    Al Khawaja, U; Al-Marzoug, S M; Bahlouli, H

    2016-05-16

    We propose a mechanism by which a number of useful all-optical operations, such as switches, diodes, and logic gates, can be performed with a single device. An effective potential well is obtained by modulating the coupling between the waveguides through their separations. Depending on the power of a control soliton injected through the potential well, an incoming soliton will either completely transmit or reflect forming a controllable switch. We show that two such switches can work as AND, OR, NAND, and NOR logic gates. Furthermore, the same device may also function as a perfect soliton diode with adjustable polarity. We discuss the feasibility of realising such devices with current experimental setups. PMID:27409929

  19. All-optical code-division multiple-access applications: 2(n) extended-prime codes.

    PubMed

    Zhang, J G; Kwong, W C; Mann, S

    1997-09-10

    A new family of 2(n) codes, called 2(n) extended-prime codes, is proposed for all-optical code-division multiple-access networks. Such 2(n) codes are derived from so-called extended-prime codes so that their cross-correlation functions are not greater than 1, as opposed to 2 for recently proposed 2(n) prime codes. As a result, a larger number of active users can now be supported by the new codes for a given bit-error rate than can be by 2(n) prime codes, while power-efficient, waveguide-integrable all-serial coding and correlating configurations proposed for the 2(n) prime codes can still be employed. PMID:18259529

  20. All optical mode controllable Er-doped random fiber laser with distributed Bragg gratings.

    PubMed

    Zhang, W L; Ma, R; Tang, C H; Rao, Y J; Zeng, X P; Yang, Z J; Wang, Z N; Gong, Y; Wang, Y S

    2015-07-01

    An all-optical method to control the lasing modes of Er-doped random fiber lasers (RFLs) is proposed and demonstrated. In the RFL, an Er-doped fiber (EDF) recoded with randomly separated fiber Bragg gratings (FBG) is used as the gain medium and randomly distributed reflectors, as well as the controllable element. By combining random feedback of the FBG array and Fresnel feedback of a cleaved fiber end, multi-mode coherent random lasing is obtained with a threshold of 14 mW and power efficiency of 14.4%. Moreover, a laterally-injected control light is used to induce local gain perturbation, providing additional gain for certain random resonance modes. As a result, active mode selection of the RFL is realized by changing locations of the laser cavity that is exposed to the control light. PMID:26125397

  1. A novel noninvasive all optical technique to monitor physiology of an exercising muscle

    NASA Astrophysics Data System (ADS)

    Saxena, Vishal; Marcu, Laura; Karunasiri, Gamani

    2008-11-01

    An all optical technique based on near-infrared spectroscopy and mid-infrared imaging (MIRI) is applied as a noninvasive, in vivo tool to monitor the vascular status of skeletal muscle and the physiological changes that occur during exercise. A near-infrared spectroscopy (NIRS) technique, namely, steady state diffuse optical spectroscopy (SSDOS) along with MIRI is applied for monitoring the changes in the values of tissue oxygenation and thermometry of an exercising muscle. The NIRS measurements are performed at five discrete wavelengths in a spectral window of 650-850 nm and MIRI is performed in a spectral window of 8-12 µm. The understanding of tissue oxygenation status and the behavior of the physiological parameters derived from thermometry may provide a useful insight into muscle physiology, therapeutic response and treatment.

  2. New approach to fault-tolerant routing in all-optical networks

    NASA Astrophysics Data System (ADS)

    Sengupta, Abhijit; Alluri, Shailesh; Bandyopadhyay, Subir; Jaekel, Arunita

    1999-08-01

    Fault management in WDM routed all-optical networks has mostly been addressed either by automatic protection switching or through loop-back recovery. These schemes are designed for managing single fault occurrence and generalization method to handle multiple faults are not known. Conventional routing schemes are static in nature (where the routers are programmed to realize the lightpaths between the end-nodes) and hence a fault management scheme needs to find a fault-free path between end-nodes using the settings of the routers. This paper considers the principle of survival route graphs to construct fault-free paths between end-nodes. As a result, the fault avoiding route between two end-nodes might be a multihop route in which the number of hops are limited to reduce the communication delay. The performance degradations of the network because of fault occurrence are studied through simulations and measured in terms of blocking probability and communication delay.

  3. All-Optical Generation and Switching of Few-Cycle Millimeter-Wave Pulses

    NASA Astrophysics Data System (ADS)

    Lin, Jim-Wein; Wun, Jhih-Min; Shi, Jin-Wei; Pan, Ci-Ling

    2014-10-01

    We conducted a comparative study of two schemes of photonic generation and switching of few-cycle sub-THz or millimeter wave (MMW) pulses by use of a photonic-transmitter-mixer (PTM) module with a broadband and high-power near-ballistic uni-traveling carrier photodiode (NBUTC-PD). In the first scheme, we performed all-optical ultra-fast switching (bias modulation) of the PTM injected with a 93 GHz optical local-oscillator signal. Sub-2-cycle short MMW pulses with central frequency at 93 GHz were generated. To compare, in scheme 2, we employed femtosecond optical short pulses to directly excite the PTM under a DC bias (optical modulation). The former approach is shown to be capable of providing much less signal distortion and much shorter pulse duration than the latter.

  4. Artificial eye for scotopic vision with bioinspired all-optical photosensitivity enhancer

    PubMed Central

    Liu, Hewei; Huang, Yinggang; Jiang, Hongrui

    2016-01-01

    The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an all-optical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems. PMID:26976565

  5. All-Optical Frequency Modulated High Pressure MEMS Sensor for Remote and Distributed Sensing

    PubMed Central

    Reck, Kasper; Thomsen, Erik V.; Hansen, Ole

    2011-01-01

    We present the design, fabrication and characterization of a new all-optical frequency modulated pressure sensor. Using the tangential strain in a circular membrane, a waveguide with an integrated nanoscale Bragg grating is strained longitudinally proportional to the applied pressure causing a shift in the Bragg wavelength. The simple and robust design combined with the small chip area of 1 × 1.8 mm2 makes the sensor ideally suited for remote and distributed sensing in harsh environments and where miniaturized sensors are required. The sensor is designed for high pressure applications up to 350 bar and with a sensitivity of 4.8 pm/bar (i.e., 350 ×105 Pa and 4.8 × 10−5 pm/Pa, respectively). PMID:22346662

  6. Femtosecond all-optical synchronization of an X-ray free-electron laser

    PubMed Central

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; Mazza, T.; Meyer, M.; Pfeiffer, S.; Prędki, P.; Schefer, S.; Schmidt, C.; Wegner, U.; Schlarb, H.; Cavalieri, A. L.

    2015-01-01

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses. PMID:25600823

  7. Femtosecond all-optical synchronization of an X-ray free-electron laser

    NASA Astrophysics Data System (ADS)

    Schulz, S.; Grguraš, I.; Behrens, C.; Bromberger, H.; Costello, J. T.; Czwalinna, M. K.; Felber, M.; Hoffmann, M. C.; Ilchen, M.; Liu, H. Y.; Mazza, T.; Meyer, M.; Pfeiffer, S.; Prędki, P.; Schefer, S.; Schmidt, C.; Wegner, U.; Schlarb, H.; Cavalieri, A. L.

    2015-01-01

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

  8. Femtosecond all-optical synchronization of an X-ray free-electron laser.

    PubMed

    Schulz, S; Grguraš, I; Behrens, C; Bromberger, H; Costello, J T; Czwalinna, M K; Felber, M; Hoffmann, M C; Ilchen, M; Liu, H Y; Mazza, T; Meyer, M; Pfeiffer, S; Prędki, P; Schefer, S; Schmidt, C; Wegner, U; Schlarb, H; Cavalieri, A L

    2015-01-01

    Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses. PMID:25600823

  9. Sequentially timed all-optical mapping photography (STAMP) utilizing spectral filtering.

    PubMed

    Suzuki, Takakazu; Isa, Fumihiro; Fujii, Leo; Hirosawa, Kenichi; Nakagawa, Keiichi; Goda, Keisuke; Sakuma, Ichiro; Kannari, Fumihiko

    2015-11-16

    We propose and experimentally demonstrate a new method called SF-STAMP for sequentially timed all-optical mapping photography (STAMP) that utilizes spectral filtering. SF-STAMP is composed of a diffractive optical element (DOE), a band-pass filter, and two Fourier transform lenses. Using a linearly frequency-chirped pulse and converting the wavelength to the time axis, we realize single-shot ultrafast burst imaging. As an experimental demonstration of SF-STAMP, we monitor the dynamics of a laser ablation using a linearly frequency-chirped broadband pulse (>100 nm) that is temporally stretched up to ~40 ps. This imaging method is expected to be effective for investigating ultrafast dynamics in a diverse range of fields, such as photochemistry, plasma physics, and fluidics. PMID:26698529

  10. Realization of all-optical logic gates through three core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Uthayakumar, T.; Vasantha Jayakantha Raja, R.; Porsezian, K.

    2013-06-01

    We present the practical design of novel three core photonic crystal fiber (TPCF) for optical switching and logic operations by employing all optical control. To accomplish the proposed aim, we put forth two types of symmetrical TPCF designs, one with cores of planar geometry and the other with equilateral triangular geometry. The dynamics of the individual pulse parameters through the proposed geometries are analyzed numerically using split step Fourier method (SSFM). The steering characteristics of the coupler are demonstrated by the transmission curve. The truth tables expressing Boolean algebra for different logic operations are constructed from the transmission curves of the individual coupler configurations. Out of all configurations, we observe that the chloroform filled triangular core demonstrates all the logic operations namely OR, NOR, AND, NAND, X-OR, X-NOR and NOT with low input power. A figure of merit of logic gates (FOMEL) is also made to compare the performance of all the logic gates.

  11. All-optical switching in silicon-on-insulator photonic wire nano-cavities.

    PubMed

    Belotti, Michele; Galli, Matteo; Gerace, Dario; Andreani, Lucio Claudio; Guizzetti, Giorgio; Md Zain, Ahmad R; Johnson, Nigel P; Sorel, Marc; De La Rue, Richard M

    2010-01-18

    We report on experimental demonstration of all-optical switching in a silicon-on-insulator photonic wire nanocavity operating at telecom wavelengths. The switching is performed with a control pulse energy as low as approximately 0.1 pJ on a cavity device that presents very high signal transmission, an ultra-high quality-factor, almost diffraction-limited modal volume and a footprint of only 5 microm(2). High-speed modulation of the cavity mode is achieved by means of optical injection of free carriers using a nanosecond pulsed laser. Experimental results are interpreted by means of finite-difference time-domain simulations. The possibility of using this device as a logic gate is also demonstrated. PMID:20173973

  12. All-optical virtual private network system in OFDM based long-reach PON using RSOA re-modulation technique

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Hun; Jung, Sang-Min; Kang, Su-Min; Han, Sang-Kook

    2015-01-01

    We propose an all-optical virtual private network (VPN) system in an orthogonal frequency division multiplexing (OFDM) based long reach PON (LR-PON). In the optical access network field, technologies based on fundamental upstream (U/S) and downstream (D/S) have been actively researched to accommodate explosion of data capacity. However, data transmission among the end users which is arisen from cloud computing, file-sharing and interactive game takes a large weight inside of internet traffic. Moreover, this traffic is predicted to increase more if Internet of Things (IoT) services are activated. In a conventional PON, VPN data is transmitted through ONU-OLT-ONU via U/S and D/S carriers. It leads to waste of bandwidth and energy due to O-E-O conversion in the OLT and round-trip propagation between OLT and remote node (RN). Also, it causes inevitable load to the OLT for electrical buffer, scheduling and routing. The network inefficiency becomes more critical in a LR-PON which has been researched as an effort to reduce CAPEX and OPEX through metro-access consolidation. In the proposed system, the VPN data is separated from conventional U/S and re-modulated on the D/S carrier by using RSOA in the ONUs to avoid bandwidth consumption of U/S and D/S unlike in previously reported system. Moreover, the transmitted VPN data is re-directed to the ONUs by wavelength selective reflector device in the RN without passing through the OLT. Experimental demonstration for the VPN communication system in an OFDM based LR-PON has been verified.

  13. Domain size criterion for the observation of all-optical helicity-dependent switching in magnetic thin films

    NASA Astrophysics Data System (ADS)

    El Hadri, Mohammed Salah; Hehn, Michel; Pirro, Philipp; Lambert, Charles-Henri; Malinowski, Grégory; Fullerton, Eric E.; Mangin, Stéphane

    2016-08-01

    To understand the necessary condition for the observation of all-optical helicity-dependent switching (AO-HDS) of magnetization in thin films, we investigated ferromagnetic Co/Pt and Co/Ni multilayers as well as ferrimagnetic TbCo alloys as a function of magnetic layer compositions and thicknesses. We show that both ferro- and ferrimagnets with high saturation magnetization show AO-HDS if their magnetic thickness is strongly reduced below a material-dependent threshold thickness. By taking into account the demagnetizing energy and the domain wall energy, we are able to define a criterion to predict whether AO-HDS or thermal demagnetization (TD) will be observed. This criterion for the observation of AO-HDS is that the equilibrium size of magnetic domains forming during the cooling process should be larger than the laser spot size. From these results we anticipate that more magnetic materials are expected to show AO-HDS. However, the effect of the optical pulses' helicity is hidden by the formation of small magnetic domains during the cooling process.

  14. Effectiveness of phase-conjugated twin waves on fiber nonlinearity in spatially multiplexed all-optical OFDM system

    NASA Astrophysics Data System (ADS)

    Hmood, Jassim K.; Noordin, Kamarul A.; Harun, Sulaiman W.

    2016-07-01

    In this paper, we investigate the effectiveness of using phase-conjugated twin waves (PCTWs) technique to mitigate fiber nonlinear impairments in spatially multiplexed all-optical orthogonal frequency division multiplexing (AO-OFDM) systems. In this technique, AO-OFDM signal and its phase-conjugated copy are directly transmitted through two identical fiber links. At the receiver, the two signals are coherently superimposed to cancel the phase noise and to enhance signal-to-noise ratio (SNR). To show the effectiveness of proposed technique, a spatially multiplexed AO-OFDM system is demonstrated by numerical simulation. AO-OFDM signal and its phase conjugated copy are optically generated by using optical coupler-based inverse fast Fourier transform (OIFFT)/fast Fourier transform (OFFT). The generated signal includes 29 subcarriers where each subcarrier is modulated by 4-quadrature amplitude modulation (4QAM) format at a symbol rate of 25 Gsymbol/s. The results reveal that transmission performance is considerably improved where the transmission distance of the proposed system is increased by ∼45% as compared to that of original system without PCTWs technique.

  15. Ultrafast all-optical arithmetic logic based on hydrogenated amorphous silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Gostimirovic, Dusan; Ye, Winnie N.

    2016-03-01

    For decades, the semiconductor industry has been steadily shrinking transistor sizes to fit more performance into a single silicon-based integrated chip. This technology has become the driving force for advances in education, transportation, and health, among others. However, transistor sizes are quickly approaching their physical limits (channel lengths are now only a few silicon atoms in length), and Moore's law will likely soon be brought to a stand-still despite many unique attempts to keep it going (FinFETs, high-k dielectrics, etc.). This technology must then be pushed further by exploring (almost) entirely new methodologies. Given the explosive growth of optical-based long-haul telecommunications, we look to apply the use of high-speed optics as a substitute to the digital model; where slow, lossy, and noisy metal interconnections act as a major bottleneck to performance. We combine the (nonlinear) optical Kerr effect with a single add-drop microring resonator to perform the fundamental AND-XOR logical operations of a half adder, by all-optical means. This process is also applied to subtraction, higher-order addition, and the realization of an all-optical arithmetic logic unit (ALU). The rings use hydrogenated amorphous silicon as a material with superior nonlinear properties to crystalline silicon, while still maintaining CMOS-compatibility and the many benefits that come with it (low cost, ease of fabrication, etc.). Our method allows for multi-gigabit-per-second data rates while maintaining simplicity and spatial minimalism in design for high-capacity manufacturing potential.

  16. All-optical light modulation in pharaonis phoborhodopsin and its application to parallel logic gates

    NASA Astrophysics Data System (ADS)

    Sharma, Parag; Roy, Sukhdev

    2004-08-01

    All-optical light modulation in pharaonis phoborhodopsin (ppR) protein has been analyzed considering its ppRO state dynamics based on nonlinear intensity-induced excited-state absorption. Amplitude modulation of a cw probe laser beam transmission at 560nm corresponding to the peak absorption of ppRO intermediate state through ppR, by a modulating cw pump laser beam at 498nm corresponding to the peak absorption of initial ppR state has been analyzed considering all six intermediate states in its photocylce using the rate equation approach. The transmission characteristics have been shown to exhibit a dip at relatively lower pump intensity values compared to bacteriorhodopsin, which is sensitive to normalized small-signal absorption coefficient (β ), rate constants of ppRM and ppRO states, and absorption of the ppRO state at 498nm. There is an optimum value of β for a given pump intensity range for which maximum modulation can be achieved. It is shown that 100% modulation can be achieved if the initial state of ppR does not absorb the probe beam. The results have been used to design low power all optical parallel NOT, AND, OR, XNOR, and the universal NAND and NOR logic gates for two cases: (i) only changing the output threshold and (ii) considering a common threshold with different β values. At typical parameters, wild-type (WT) ppR based logic gates can be realized at considerably lower pump powers than WT-bR.

  17. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    NASA Technical Reports Server (NTRS)

    Curley, M.; Sarkisov, S. S.; Fields, A.; Smith, C.; Kukhtarev, N.; Kulishov, M. B.; Adamovsky, G. (Technical Monitor)

    2000-01-01

    An all-optical micro motor with a rotor driven by a traveling wave of surface deformation of a stator being in contact with the rotor is being studied. Instead of an ultrasonic wave produced by an electrically driven piezoelectric actuator as in ultrasonic motors, the wave is a result of a photo induced surface deformation of a photosensitive material produced by a traveling holographic grating. Two phase modulated coherent optical beams generate the grating. Several types of photosensitive materials are studied such as photorefractive crystals, photosensitive piezoelectric ceramics, and side-chain liquid crystalline polyesters. In order to be considered as a possible candidate for micro motors, the material should exhibit surface deformation produced by moving grating of the order of 10 micron. Deformations produced by static holographic gratings are studied in photorefractive crystals of LiNbO3 using high vertical resolution surface profilometer Dektak 3 and surface interferometer WYKO. An experimental set-up with moving grating has been developed. The set-up uses a two-beam interferometry configuration with one beam being reflected by a thin mirror mounted on a loud speaker. A ramp voltage signal generator drives the speaker. Changing voltage, polarity, and frequency of the signal can easily generate vibrating gratings or moving gratings in both directions. A vibrating grating has been applied to a photorefractive crystal of BSO controlled by an external electric field of the order of 104 V/cm. We have additionally studied effects of moving grating interaction with light absorbing fluids such as solutions of 2,9,16,23-Tetrakis(phenylthio)-29H, 31 Hphthalocyanine in chlorobenzene in capillary tubes. The purpose of using a liquid is to show that the moving gratings can force a liquid to shift. The interaction of a single low power focused laser beam at 633 nm with such fluid produced an intensive circular motion, which also might be applied to all-optical micro

  18. All-optical pulse-echo ultrasound probe for intravascular imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Colchester, Richard J.; Noimark, Sacha; Mosse, Charles A.; Zhang, Edward Z.; Beard, Paul C.; Parkin, Ivan P.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2016-02-01

    High frequency ultrasound probes such as intravascular ultrasound (IVUS) and intracardiac echocardiography (ICE) catheters can be invaluable for guiding minimally invasive medical procedures in cardiology such as coronary stent placement and ablation. With current-generation ultrasound probes, ultrasound is generated and received electrically. The complexities involved with fabricating these electrical probes can result in high costs that limit their clinical applicability. Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts. They offer several distinguishing advantages, including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution imaging. In this study, we developed a miniature, side-looking, pulse-echo ultrasound probe for intravascular imaging, with fibre-optic transmission and reception. The axial resolution was better than 70 microns, and the imaging depth in tissue was greater than 1 cm. Ultrasound transmission was performed by photoacoustic excitation of a carbon nanotube/polydimethylsiloxane composite material; ultrasound reception, with a fibre-optic Fabry-Perot cavity. Ex vivo tissue studies, which included healthy swine tissue and diseased human tissue, demonstrated the strong potential of this technique. To our knowledge, this is the first study to achieve an all-optical pulse-echo ultrasound probe for intravascular imaging. The potential for performing all-optical B-mode imaging (2D and 3D) with virtual arrays of transmit/receive elements, and hybrid imaging with pulse-echo ultrasound and photoacoustic sensing are discussed.

  19. All-optical photoacoustic microscopy (AOPAM) system for remote characterization of biological tissues

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Chitnis, Parag V.; Silverman, Ronald H.

    2014-03-01

    Conventional photoacoustic microscopy (PAM) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target. The resolution of conventional PAM is limited by the sensitivity and bandwidth of the ultrasound transducer. We investigated a versatile, all-optical PAM (AOPAM) system for characterizing in vivo as well as ex vivo biological specimens. The system employs non-contact interferometric detection of PA signals that overcomes limitations of conventional PAM. A 532-nm pump laser with a pulse duration of 5 ns excites the PA effect in tissue. Resulting acoustic waves produce surface displacements that are sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a 1- GHz bandwidth. The pump and probe beams are coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam is demodulated using homodyne methods. The detected timedomain signal is time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. A minimum surface-displacement sensitivity of 0.19 pm was measured. PA-induced surface displacements are very small; therefore, they impose stringent detection requirements and determine the feasibility of implementing an all-optical PAM in biomedical applications. 3D PA images of ex vivo porcine retina specimens were generated successfully. We believe the AOPAM system potentially is well suited for assessing retinal diseases and other near-surface biomedical applications such as sectionless histology and evaluation of skin burns and pressure or friction ulcers.

  20. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    NASA Technical Reports Server (NTRS)

    Adamovsky, Gregory (Technical Monitor); Curley, M.; Sarkisov, S.; Fields, A.

    2003-01-01

    This research effort was a feasibility study of the concept of an all-optical micro motor with a rotor driven by a traveling wave. The wave was a result of a photo induced surface deformation of a photosensitive material produced by a traveling holographic grating. Two phases modulated coherent optical beams were used to generate the grating in two types of photosensitive materials. The materials that were studied were photorefractive crystals and thin polymer films. Theoretical studies were performed on lithium niobate giving predictions of deformations of the order of nanometers. The experimental deformation size was also on the order of nanometers. The deformations were deep enough to provide conditions for the implementation of the all-optical motor using lithium niobate. We also were able to align micron-size dielectric particles along the holographic gratings by means of the periodic electric forces generated by the grating. These forces can also move the particles along the surface if the grating is moving. We then turned our attention on thin films and obtained a deformation visible on the order of 100 microns. An experimental breadboard demonstration of a prototype was done in the summer of 2001 at Glenn Research Center (GRC). The demonstration included the movement of clocks mechanical workings by an optically driven motor based on a polymer film. The application of this technology can be adapted to government as well as industrial uses. One such project is to make a chemical sensor for the detection of hazardous chemicals. The thin polymer film is highly suited for this purpose since a marker dye could be easily placed on the film in order to detect chemical compounds. This system could be a self-regulating chemical monitoring system used on launches of the space shuttle or locations where hazardous chemicals are present. The project provided support for two black minority graduate students targeting MS and PhD degrees in Applied Optics.

  1. All-optical optoacoustic microscopy system based on probe beam deflection technique

    NASA Astrophysics Data System (ADS)

    Maswadi, Saher M.; Tsyboulskic, Dmitri; Roth, Caleb C.; Glickman, Randolph D.; Beier, Hope T.; Oraevsky, Alexander A.; Ibey, Bennett L.

    2016-03-01

    It is difficult to achieve sub-micron resolution in backward mode OA microscopy using conventional piezoelectric detectors, because of wavefront distortions caused by components placed in the optical path, between the sample and the objective lens, that are required to separate the acoustic wave from the optical beam. As an alternate approach, an optoacoustic microscope (OAM) was constructed using the probe beam deflection technique (PBDT) to detect laserinduced acoustic signals. The all-optical OAM detects laser-generated pressure waves using a probe beam passing through a coupling medium, such as water, filling the space between the microscope objective lens and sample. The acoustic waves generated in the sample propagate through the coupling medium, causing transient changes in the refractive index that deflect the probe beam. These deflections are measured with a high-speed, balanced photodiode position detector. The deflection amplitude is directly proportional to the magnitude of the acoustic pressure wave, and provides the data required for image reconstruction. The sensitivity of the PBDT detector expressed as noise equivalent pressure was 12 Pa, comparable to that of existing high-performance ultrasound detectors. Because of the unimpeded working distance, a high numerical aperture objective lens, i.e. NA = 1, was employed in the OAM to achieve near diffraction-limited lateral resolution of 0.5 μm at 532nm. The all-optical OAM provides several benefits over current piezoelectric detector-based systems, such as increased lateral and axial resolution, higher sensitivity, robustness, and potentially more compatibility with multimodal instruments.

  2. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    PubMed Central

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  3. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal

    NASA Astrophysics Data System (ADS)

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-08-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature ‘prototype’ PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits.

  4. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal.

    PubMed

    Wang, Cheng-Yu; Chen, Chun-Wei; Jau, Hung-Chang; Li, Cheng-Chang; Cheng, Chiao-Yu; Wang, Chun-Ta; Leng, Shi-Ee; Khoo, Iam-Choon; Lin, Tsung-Hsien

    2016-01-01

    In this paper, we show that anisotropic photosensitive nematic liquid crystals (PNLC) made by incorporating anisotropic absorbing dyes are promising candidates for constructing all-optical elements by virtue of the extraordinarily large optical nonlinearity of the nematic host. In particular, we have demonstrated several room-temperature 'prototype' PNLC-based all-optical devices such as optical diode, optical transistor and all primary logic gate operations (OR, AND, NOT) based on such optical transistor. Owing to the anisotropic absorption property and the optical activity of the twist alignment nematic cell, spatially non-reciprocal transmission response can be obtained within a sizeable optical isolation region of ~210 mW. Exploiting the same mechanisms, a tri-terminal configuration as an all-optical analogue of a bipolar junction transistor is fabricated. Its ability to be switched by an optical field enables us to realize an all-optical transistor and demonstrate cascadability, signal fan-out, logic restoration, and various logical gate operations such as OR, AND and NOT. Due to the possibility of synthesizing anisotropic dyes and wide ranging choice of liquid crystals nonlinear optical mechanisms, these all-optical operations can be optimized to have much lower thresholds and faster response speeds. The demonstrated capabilities of these devices have shown great potential in all-optical control system and photonic integrated circuits. PMID:27491391

  5. The Multi-View Lightweight Virtual File System: Simplifying Collaboration with In-line Data Format Conversion and Big Data Volume Streaming

    NASA Astrophysics Data System (ADS)

    Golpayegani, N.; Halem, M.; Ederer, G.; Mauoka, E.

    2014-12-01

    Effective collaboration starts with the ability to easily and reliably access data across data center holdings regardless of data format. Incorporating a seamless data format conversion system with multiple organizational views of the data presents a formidable challenge given the many different file formats and variable ways data is organized by different data centers for data discovery and file retrieval. We will present results on how the Multi-View Lightweight Virtual File System (MLVFS) can be used by a broad range of machines to seamlessly access data from multiple data centers in client requested formats and views. We consider two aspects for effective collaboration: first, seeing what data are available, and second, accessing and converting the data on the fly. There are many tools which address these problems. For example, protocols such as OGC-WCS and OPeNDAP allow for standardized methods of data discovery, retrieval, and format conversions. Custom tools developed in-house are used to provide multiple views of available data. These solutions, however, require separate data search, retrieval, or conversion stages, and usually require local storage to hold the converted data. Additionally, these solutions require custom tools to be developed specifically for accessing a particular data center. With MLVFS, we take a radically different approach to this problem. Data centers can provide their data sets in any desired format or organized in any organizational view using well established protocols. Collaborators will see all datasets of interest to them appear on their local desktops without having to retrieve the data prior to using it. Additionally, MLVFS will perform on the fly conversion of the datasets stored at the data center to the desired format. MLVFS will free the users from unnecessary tasks, such as data retrieval and conversion, and will allow them to concentrate on tasks related to using the datasets. MLVFS will also free up available resources

  6. All-optical devices based on carrier nonlinearities for optical filtering and spectral equalization

    NASA Astrophysics Data System (ADS)

    Burger, Johan Petrus

    InGaAsP-based quantum wells can display nonlinear refractive index changes of ~0.1 near the band-edge for intrawell carrier density changes of 1 × 1018cm-3, due to effects like bandfilling and the plasma effect, which make these materials promising for the realization of all-optical signal processing devices, as demonstrated here. A novel single passband filter with sub-gigahertz bandwidth and greater than 40nm of tunability was experimentally demonstrated. The filter uses the detuning characteristics of nearly degenerate four-wave mixing in a broad area semiconductor optical amplifier to obtain frequency selectivity. The key to this demonstration was the spatial separation of the filtered signal from the input signal, based on their different propagation directions. An analysis of an analogous integrated optic dual-order mode nonlinear mode-converter, with integrated mode sorters which separate the signal from the interacting modes, was also undertaken. This device is promising as a filter, a wavelength converter, notch filter, and a wavelength recognizing switch. Novel ways to prevent carrier diffusion, which washes out the nonlinear grating, were suggested. It is important to have a large mutual overlap to modal overlap ratio of the two interacting modes on the nonlinear medium, because the mixing efficiency scales as the fourth power of this number. Three types of integrated optic limiters (based on Kerr- like nonlinearities) namely an all-optical cutoff modulator, a nonlinear Y-branch and an interferometer with an internal Kerr element, were theoretically investigated. A beam propagation program, which can solve the propagation of an optical field in a semiconductor in the presence of carrier diffusion, was developed for the numerical analysis of these structures. A negative feedback mechanism was identified in the Y-branch devices and a new limiting configuration was discovered in a Y- branch with a selectively placed defocusing nonlinearity. Dichroic

  7. Using magnetic resonance imaging to monitor CH4 hydrate formation and spontaneous conversion of CH4 hydrate to CO2 hydrate in porous media.

    PubMed

    Baldwin, Bernard A; Stevens, Jim; Howard, James J; Graue, Arne; Kvamme, Bjorn; Aspenes, Erick; Ersland, Geir; Husebø, Jarle; Zornes, David R

    2009-06-01

    Magnetic resonance imaging was used to monitor and quantify methane hydrate formation and exchange in porous media. Conversion of methane hydrate to carbon dioxide hydrate, when exposed to liquid carbon dioxide at 8.27 MPa and approximately 4 degrees C, was experimentally demonstrated with MRI data and verified by mass balance calculations of consumed volumes of gases and liquids. No detectable dissociation of the hydrate was measured during the exchange process. PMID:19168304

  8. All-optical power and data transfer in catheters using an efficient LED

    NASA Astrophysics Data System (ADS)

    van der Mark, Martin B.; van Dusschoten, Anneke; Pekar, Martin

    2015-03-01

    Diagnostic value of minimally invasive medical devices can be improved by putting electronic functionality at the tip. At the same time the device should remain slim, flexible and affordable. We show transfer of high power and data over a catheter by a single optical fiber and LED. We find that simultaneous photovoltaic power conversion and data communication can be achieved via Photo-Induced Electro Luminescence (PEL), but only in case the LED has a high bidirectional conversion efficiency (η<0.3). This eliminates the necessity of using thin electrical wires with fragile interconnects that compromise bandwidth as well as RF and MRI compatibility.

  9. All-optical frequency upconversion of a quasi optical single sideband signal utilizing a nonlinear semiconductor optical amplifier for radio-over-fiber applications.

    PubMed

    Park, Minho; Song, Jong-In

    2011-11-21

    An all-optical frequency upconversion technique using a quasi optical single sideband (q-OSSB) signal in a nonlinear semiconductor optical amplifier (NSOA) for radio-over-fiber applications is proposed and experimentally demonstrated. An optical radio frequency signal (f(RF) = 37.5 GHz) in the form of a q-OSSB signal is generated by mixing an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) with an optical local oscillator signal (f(LO) = 35 GHz) utilizing coherent population oscillation and cross gain modulation effects in an NSOA. The phase noise, conversion efficiency, spurious free dynamic range (SFDR), and transmission characteristics of the q-OSSB signal are investigated. PMID:22109476

  10. Robust conversion of marrow cells to skeletal muscle with formation of marrow-derived muscle cell colonies: A multifactorial process

    SciTech Connect

    Abedi, Mehrdad; Greer, Deborah A.; Colvin, Gerald A.; Demers, Delia A.; Dooner, Mark S.; Harpel, Jasha A.; Weier, Heinz-Ulrich G.; Lambert, Jean-Francois; Quesenberry, Peter J.

    2004-01-10

    Murine marrow cells are capable of repopulating skeletal muscle fibers. A point of concern has been the robustness of such conversions. We have investigated the impact of type of cell delivery, muscle injury, nature of delivered cell, and stem cell mobilizations on marrow to muscle conversion. We transplanted GFP transgenic marrow into irradiated C57BL/6 mice and then injured anterior tibialis muscle by cardiotoxin. One month after injury, sections were analyzed by standard and deconvolutional microscopy for expression of muscle and hematopietic markers. Irradiation was essential to conversion although whether by injury or induction of chimerism is not clear. Cardiotoxin and to a lesser extent PBS injected muscles showed significant number of GFP+ muscle fibers while uninjected muscles showed only rare GFP+ cells. Marrow conversion to muscle was increased by two cycles of G-CSF mobilization and to a lesser extent with G-CSF and steel or GM-CSF. Transplantation of female GFP to male C57 BL/6 and GFP to Rosa26 mice showed fusion of donor cells to recipient muscle. High numbers of donor derived muscle colonies and up to12 percent GFP positive muscle cells were seen after mobilization or direct injection. These levels of donor muscle chimerism approach levels which could be clinically significant in developing strategies for the treatment of muscular dystrophies. In summary, the conversion of marrow to skeletal muscle cells is based on cell fusion and is critically dependent on injury. This conversion is also numerically significant and increases with mobilization.

  11. Ultralow bias power all-optical photonic crystal memory realized with systematically tuned L3 nanocavity

    SciTech Connect

    Kuramochi, Eiichi Nozaki, Kengo; Shinya, Akihiko; Taniyama, Hideaki; Notomi, Masaya; Takeda, Koji; Matsuo, Shinji; Sato, Tomonari

    2015-11-30

    An InP photonic crystal nanocavity with an embedded InGaAsP active region is a unique technology that has realized an all-optical memory with a sub-micro-watt operating power and limitless storage time. In this study, we employed an L3 design with systematic multi-hole tuning, which realized a higher loaded Q factor (>40 000) and a lower mode volume (0.9 μm{sup 3}) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm{sup 3}). Excluding the active region realized a record loaded Q factor (210 000) in all for InP-based nanocavities. The minimum bias power for bistable memory operation was reduced to 2.3 ± 0.3 nW, which is about 1/10 of the previous record of 30 nW. This work further established the capability of a bistable nanocavity memory for use in future ultralow-power-consumption on-chip integrated photonics.

  12. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    NASA Astrophysics Data System (ADS)

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; de Koninck, Paul

    2016-02-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling.

  13. Proposal of all-optical sensor based on nonlinear MMI coupler for multi-purpose usage

    NASA Astrophysics Data System (ADS)

    Tajaldini, M.; MatJafri, M. Z.

    2015-10-01

    In this study, we propose an all-optical sensor based on consideration the nonlinear effects on modal propagation and output intensity based on ultra-compact nonlinear multimode interference (NLMMI) coupler. The sensor can be tuned to highest sensitivity in the wavelength and refractive index ranges sufficient to detect water- soluble chemical, air pollutions, and heart operation. The results indicate high output sensitivity to input wavelength. This sensitivity guides us to propose a wave sensor both transverse and longitudinal waves such as acoustic and light wave, when an external wave interacts with input waveguide. For instance, this sensor can be implemented by long input that inserted in the land, then any wave could detected from earth. The visible changes of intensity at output facet in various surrounding layer refractive index show the high sensitivity to the refractive index of surrounding layer that is foundation of introducing a sensor. Also, the results show the high distinguished changes on modal expansion and output throat distribution in various refractive indices of surrounding layer.

  14. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes

    NASA Astrophysics Data System (ADS)

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L.; Chekulaev, Dimitri; Canham, Leigh T.; Kaplan, Andre

    2016-07-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm2). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications.

  15. All-optical central-frequency-programmable and bandwidth-tailorable radar

    PubMed Central

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

  16. Nanophotonic technologies for innovative all- optical signal processor using photonic crystals and quantum dots

    SciTech Connect

    Sugimoto, Y.; Ikeda, N.; Ozaki, N.; Watanabe, Y.; Asakawa, K.; Ohkouchi, S.; Nakamura, S.

    2009-06-29

    GaAs-based two-dimensional photonic crystal (2DPC) slab waveguides (WGs) and InAs quantum dots (QDs) were developed for key photonic device structures in the future. An ultrasmall and ultrafast symmetrical Mach-Zehnder (SMZ)-type all-optical switch (PC-SMZ) and an optical flip-flop device (PC-FF) have been developed based on these nanophotonic structures for an ultrafast digital photonic network. To realize these devices, two important techniques were developed. One is a new simulation method, i.e., topology optimization method of 2DPC WGs with wide/flat bandwidth, high transmittance and low reflectivity. Another is a new selective-area-growth method, i.e., metal-mask molecular beam epitaxy method of InAs QDs. This technique contributes to achieving high-density and highly uniform InAs QDs in a desired area such as an optical nonlinearity-induced phase shift arm in the PC-FF. Furthermore, as a unique site-controlled QD technique, a nano-jet probe method is also developed for positioning QDs at the centre of the optical nonlinearity-induced phase shift arm.

  17. A simple and effective theory for all-optical helicity-dependent spin switching

    NASA Astrophysics Data System (ADS)

    Zhang, Guoping; Bai, Yihua; George, Thomas F.

    All-optical helicity-dependent spin switching (AOS) represents a new frontier in magnetic recording technology, where a single ultrafast laser pulse, without any assistance from an external magnetic field, can permanently switch spin within a few hundred femtoseconds. By contrast, the existing theory does rely on an artificial magnetic field to switch spins. Here we develop a microscopic spin switch theory, free of any artificial field, and demonstrate unambiguously that both circularly and linearly polarized lights can switch spins faithfully. Our theory is based on the Hookean theory, but includes two new elements: spin-orbit coupling and exchange interaction. We predict that left (right) circularly polarized light only flips (flops) spin, a symmetry constraint that strongly favors ferrimagnetic orderings over ferromagnetic ones, with the allowable exchange interaction within 10 meV, consistent with all prior theories. The effect of the laser amplitude is highly nonlinear: If it is too weak, AOS does not occur, but if too strong, the spin cants; a compromise between them produces a narrow spin reversal window as observed experimentally. We envision that our model can be easily extended to describe spin frustrated systems and multiferroics, where the light-spin interaction Supported by the U.S. Department of Energy under Contract No. DE-FG02-06ER46304 and the National Energy Research Scientific Computing Center.

  18. Rapid, all-optical crystal orientation imaging of two-dimensional transition metal dichalcogenide monolayers

    SciTech Connect

    David, Sabrina N.; Zhai, Yao; Zande, Arend M. van der; O'Brien, Kevin; Huang, Pinshane Y.; Chenet, Daniel A.; Hone, James C.; Zhang, Xiang; Yin, Xiaobo

    2015-09-14

    Two-dimensional (2D) atomic materials such as graphene and transition metal dichalcogenides (TMDCs) have attracted significant research and industrial interest for their electronic, optical, mechanical, and thermal properties. While large-area crystal growth techniques such as chemical vapor deposition have been demonstrated, the presence of grain boundaries and orientation of grains arising in such growths substantially affect the physical properties of the materials. There is currently no scalable characterization method for determining these boundaries and orientations over a large sample area. We here present a second-harmonic generation based microscopy technique for rapidly mapping grain orientations and boundaries of 2D TMDCs. We experimentally demonstrate the capability to map large samples to an angular resolution of ±1° with minimal sample preparation and without involved analysis. A direct comparison of the all-optical grain orientation maps against results obtained by diffraction-filtered dark-field transmission electron microscopy plus selected-area electron diffraction on identical TMDC samples is provided. This rapid and accurate tool should enable large-area characterization of TMDC samples for expedited studies of grain boundary effects and the efficient characterization of industrial-scale production techniques.

  19. All-optical OFDM transmitter design using AWGRs and low-bandwidth modulators

    NASA Astrophysics Data System (ADS)

    Lowery, Arthur James; Du, Liang

    2011-08-01

    An Arrayed-Waveguide Grating Router (AWGR) can be used as a demultiplexer for an optical OFDM system, as it provides both the serial-to-parallel converter and the optical Fourier transform (FT) in one component. Because an inverse FT is topologically identical to a Fourier transform, the AWGR can also be used as a FT in an OFDM transmitter. In most all-optical OFDM systems the optical modulators are fed with CW tones; however, the subcarriers (SC) will only be perfectly orthogonal if the bandwidth of the data modulators is similar to the total bandwidth of all subcarriers. Using simulations, this paper investigates the reduction in modulator bandwidth that could be achieved if the modulators are placed before an AWGR designed as a FT. This arrangement also allows the complex (IQ) modulators to be replaced with simpler and more-compact phase modulators. We show that these design improvements enable 7.5-GHz bandwidth modulators to be used in a 4 - 10 Gsymbol/s (80 Gbit/s) per polarization per wavelength system.

  20. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications.

    PubMed

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J; Ramírez-Miquet, Evelio E; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-01-01

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications. PMID:27187406

  1. Analysis of all-optical light modulation in proteorhodopsin protein molecules

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Sharma, Parag

    2008-03-01

    We present a detailed steady-state and time-dependent theoretical analysis of all-optical light modulation in the recently discovered, wild-type proteorhodopsin (WTpR) protein molecules based on excited-state absorption. Amplitude modulation of cw probe laser beam transmissions at 520, 405, 555 and 560 nm, corresponding to the peak absorption of pR, pRM, pRK and pRN intermediate states of pR photocycle, respectively, by cw and pulsed modulating pump laser beam at 520 nm have been analyzed. The effect of various spectral and kinetic parameters on modulation characteristics has been studied. There is an optimum value of concentration for a given pump intensity value for which maximum modulation of the probe beam can be achieved. The switching characteristics of probe beam at 405 and 520 nm exhibit dip and peak, respectively, which can be removed by decreasing the absorption of pRM state at 520 nm. The modulation in WTpR is at lower pump powers with smaller contrast in comparison to WT bacteriorhodopsin (bR) and WT pharaonis phoborhodopsin (ppR). The modulation characteristics exhibit unique features compared to bR and ppR.

  2. All-optical central-frequency-programmable and bandwidth-tailorable radar.

    PubMed

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution. PMID:26795596

  3. Design of photonic crystal-based all-optical AND gate using T-shaped waveguide

    NASA Astrophysics Data System (ADS)

    haq Shaik, Enaul; Rangaswamy, Nakkeeran

    2016-05-01

    We present a new configuration of all-optical AND gate based on two-dimensional photonic crystal composed of Si rods in air. Two AND gate structures with and without probe input are proposed. The proposed structures are designed with T-shaped waveguide without using nonlinear materials and optical amplifiers. The performance of the proposed AND gate structures is analyzed and simulated by plane-wave expansion and finite difference time domain methods. The AND gate without probe input needs only one T-shaped waveguide, whereas the AND gate with probe input needs two T-shaped waveguides. The former AND gate offers a bit rate of 6.26 Tbps with a contrast ratio of 5.74 dB, whereas the latter AND gate offers a bit rate of 3.58 Tbps whose contrast ratio is 9.66 dB. It can be expected that these small size T-shaped structures are suitable for large-scale integration and can potentially be used in on-chip photonic integrated circuits.

  4. All-optical central-frequency-programmable and bandwidth-tailorable radar

    NASA Astrophysics Data System (ADS)

    Zou, Weiwen; Zhang, Hao; Long, Xin; Zhang, Siteng; Cui, Yuanjun; Chen, Jianping

    2016-01-01

    Radar has been widely used for military, security, and rescue purposes, and modern radar should be reconfigurable at multi-bands and have programmable central frequencies and considerable bandwidth agility. Microwave photonics or photonics-assisted radio-frequency technology is a unique solution to providing such capabilities. Here, we demonstrate an all-optical central-frequency-programmable and bandwidth-tailorable radar architecture that provides a coherent system and utilizes one mode-locked laser for both signal generation and reception. Heterodyning of two individually filtered optical pulses that are pre-chirped via wavelength-to-time mapping generates a wideband linearly chirped radar signal. The working bands can be flexibly tailored with the desired bandwidth at a user-preferred carrier frequency. Radar echoes are first modulated onto the pre-chirped optical pulse, which is also used for signal generation, and then stretched in time or compressed in frequency several fold based on the time-stretch principle. Thus, digitization is facilitated without loss of detection ability. We believe that our results demonstrate an innovative radar architecture with an ultra-high-range resolution.

  5. All-optical anatomical co-registration for molecular imaging of small animals using dynamic contrast

    NASA Astrophysics Data System (ADS)

    Hillman, Elizabeth M. C.; Moore, Anna

    2007-09-01

    Optical molecular imaging in small animals harnesses the power of highly specific and biocompatible contrast agents for drug development and disease research. However, the widespread adoption of in vivo optical imaging has been inhibited by its inability to clearly resolve and identify targeted internal organs. Optical tomography and combined X-ray and micro-computed tomography (micro-CT) approaches developed to address this problem are generally expensive, complex or incapable of true anatomical co-registration. Here, we present a remarkably simple all-optical method that can generate co-registered anatomical maps of a mouse's internal organs, while also acquiring in vivo molecular imaging data. The technique uses a time series of images acquired after injection of an inert dye. Differences in the dye's in vivo biodistribution dynamics allow precise delineation and identification of major organs. Such co-registered anatomical maps permit longitudinal organ identification irrespective of repositioning or weight gain, thereby promising greatly improved accuracy and versatility for studies of orthotopic disease, diagnostics and therapies.

  6. Green Distributed Quality of Transmission Aware Routing and Wavelength Assignment in All-Optical Networks

    NASA Astrophysics Data System (ADS)

    Kakekhani, Amir; Rahbar, Akbar Ghaffarpour

    2013-06-01

    The Routing and Wavelength Assignment (RWA) algorithms that consider quality of transmission (QoT) in light-path setup spend more time than their conventional counterparts due to exhaustive search and QoT estimation. This paper proposes distributed Quality of Transmission Aware Routing and Wavelength Assignment (QARWA) algorithm to handle dynamic light-path provisioning in wavelength routed all-optical networks taking energy consumption of optical switch nodes into account. Specifically, the QARWA considers bit-error rate (BER), setup delay, and energy consumption constraints at the same time, and establishes light-paths with small BER, low setup latency, and reduced energy consumption. We present and evaluate an enhanced wavelength-assignment solution in the QARWA to handle the wavelength continuity constraint. In QARWA, a source node determines the connection path by means of the shortest path algorithm and a destination node selects a wavelength based on the BER limitation and decreasing order of setup latency. Relating energy consumption to processing time, we show that QARWA can decrease the total energy consumption by reducing the processing time at each node. Under QARWA, when a node finishes the processing of the last control packet, it makes transition to either sleep state or idle state. Hence, QARWA can provide the best performance since it can reduce processing time in control units, light-path setup latency, and energy consumption of nodes.

  7. All-optical frame clock recovery from even-multiplexed OTDM signals

    NASA Astrophysics Data System (ADS)

    Yin, Lina; Liu, Guoming; Wu, Jian; Lin, Jintong

    2005-02-01

    Frame clock is useful for packet processing such as header detection and payload demultiplexing. A novel all-optical frame clock recovery scheme based on "intensity reshaper" and mode-locked semiconductor fiber ring laser is demonstrated. The "intensity reshaper" including a polarization controller and a polarizer is the key element to realize frame clock recovery from equal-amplitude even-multiplexed OTDM signals. In theory, a mathematical expression is given to analyze the intensity of harmonic of clock-frequency component. The relative intensity of each clock-frequency component will change with the alterative angle caused by adjusting the PC in the "intensity reshaper", so the desirable clock-frequency component can be enhanced, which is helpful for clock recovery. Moreover, the intensity of harmonic of clock-frequency component is also related to the pulse amplitude, width and period in the multiplexed data. In experiment, 2.5GHz frame clock is extracted from even-multiplexed 4x2.5GHz and 8x2.5GHz OTDM signals respectively. At the same time, bit clock is also recovered by using this scheme. The extracted clock pulses have several desirable features such as low timing jitter, broad wavelength tuning range and polarization independence. This scheme simplifies signal generation and propagation in OTDM systems, which can be applied to clock recovery in high-speed OTDM network.

  8. All-optical OFDM transmitter design using AWGRs and low-bandwidth modulators.

    PubMed

    Lowery, Arthur James; Du, Liang

    2011-08-15

    An Arrayed-Waveguide Grating Router (AWGR) can be used as a demultiplexer for an optical OFDM system, as it provides both the serial-to-parallel converter and the optical Fourier transform (FT) in one component. Because an inverse FT is topologically identical to a Fourier transform, the AWGR can also be used as a FT in an OFDM transmitter. In most all-optical OFDM systems the optical modulators are fed with CW tones; however, the subcarriers (SC) will only be perfectly orthogonal if the bandwidth of the data modulators is similar to the total bandwidth of all subcarriers. Using simulations, this paper investigates the reduction in modulator bandwidth that could be achieved if the modulators are placed before an AWGR designed as a FT. This arrangement also allows the complex (IQ) modulators to be replaced with simpler and more-compact phase modulators. We show that these design improvements enable 7.5-GHz bandwidth modulators to be used in a 4 × 10 Gsymbol/s (80 Gbit/s) per polarization per wavelength system. PMID:21934931

  9. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications

    PubMed Central

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J.; Ramírez-Miquet, Evelio E.; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-01-01

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications. PMID:27187406

  10. Quantum-dot all-optical logic in a structured vacuum

    SciTech Connect

    Ma Xun; John, Sajeev

    2011-07-15

    We demonstrate multiwavelength channel optical logic operations on the Bloch vector of a quantum two-level system in the structured electromagnetic vacuum of a bimodal photonic crystal waveguide. This arises through a bichromatic strong-coupling effect that enables unprecedented control over single quantum-dot (QD) excitation through two beams of ultrashort femtojoule pulses. The second driving pulse (signal) with slightly different frequency and weaker strength than the first (holding) pulse leads to controllable strong modulation of the QD Bloch vector evolution path. This occurs through resonant coupling of the signal pulse with the Mollow sideband transitions created by the holding pulse. The movement of the Mollow sidebands during the passage of the holding pulse leads to an effective chirping in transition frequency seen by the signal. Bloch vector dynamics in the rotating frame of the signal pulse and within the dressed-state basis created by the holding pulse reveals that this chirped coupling between the signal pulse and the Mollow sidebands leads to either augmentation or negation of the final quantum-dot population (after pulse passage) compared to the outcome of the holding pulse alone and depending on the relative frequencies of the pulses. By making use of this extra degree of freedom for ultrafast control of QD excitations, applications in ultrafast all-optical logic and, or, and not gates are proposed in the presence of significant (0.1) THz nonradiative dephasing and (about 1%) inhomogeneous broadening.

  11. Ultralow bias power all-optical photonic crystal memory realized with systematically tuned L3 nanocavity

    NASA Astrophysics Data System (ADS)

    Kuramochi, Eiichi; Nozaki, Kengo; Shinya, Akihiko; Taniyama, Hideaki; Takeda, Koji; Sato, Tomonari; Matsuo, Shinji; Notomi, Masaya

    2015-11-01

    An InP photonic crystal nanocavity with an embedded InGaAsP active region is a unique technology that has realized an all-optical memory with a sub-micro-watt operating power and limitless storage time. In this study, we employed an L3 design with systematic multi-hole tuning, which realized a higher loaded Q factor (>40 000) and a lower mode volume (0.9 μm3) than a line-defect-based buried-heterostructure nanocavity (16 000 and 2.2 μm3). Excluding the active region realized a record loaded Q factor (210 000) in all for InP-based nanocavities. The minimum bias power for bistable memory operation was reduced to 2.3 ± 0.3 nW, which is about 1/10 of the previous record of 30 nW. This work further established the capability of a bistable nanocavity memory for use in future ultralow-power-consumption on-chip integrated photonics.

  12. Ultra fast all-optical fiber pressure sensor for blast event evaluation

    NASA Astrophysics Data System (ADS)

    Wu, Nan; Wang, Wenhui; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2011-05-01

    Traumatic brain injury (TBI) is a great potential threat to soldiers who are exposed to explosions or athletes who receive cranial impacts. Protecting people from TBI has recently attracted a significant amount of attention due to recent military operations in the Middle East. Recording pressure transient data in a blast event is very critical to the understanding of the effects of blast events on TBI. However, due to the fast change of the pressure during blast events, very few sensors have the capability to effectively track the dynamic pressure transients. This paper reports an ultra fast, miniature and all-optical fiber pressure sensor which could be mounted at different locations of a helmet to measure the fast changing pressure simultaneously. The sensor is based on Fabry-Perot (FP) principle. The end face of the fiber is wet etched. A well controlled thickness silicon dioxide diaphragm is thermal bonded on the end face to form an FP cavity. A shock tube test was conducted at Natick Soldier Research Development and Engineering Center, where the sensors were mounted in a shock tube side by side with a reference sensor to measure the rapidly changing pressure. The results of the test demonstrated that the sensor developed had an improved rise time (shorter than 0.4 μs) when compared to a commercially available reference sensor.

  13. Superstructures of chiral nematic microspheres as all-optical switchable distributors of light

    PubMed Central

    Aβhoff, Sarah J.; Sukas, Sertan; Yamaguchi, Tadatsugu; Hommersom, Catharina A.; Le Gac, Séverine; Katsonis, Nathalie

    2015-01-01

    Light technology is based on generating, detecting and controlling the wavelength, polarization and direction of light. Emerging applications range from electronics and telecommunication to health, defence and security. In particular, data transmission and communication technologies are currently asking for increasingly complex and fast devices, and therefore there is a growing interest in materials that can be used to transmit light and also to control the distribution of light in space and time. Here, we design chiral nematic microspheres whose shape enables them to reflect light of different wavelengths and handedness in all directions. Assembled in organized hexagonal superstructures, these microspheres of well-defined sizes communicate optically with high selectivity for the colour and chirality of light. Importantly, when the microspheres are doped with photo-responsive molecular switches, their chiroptical communication can be tuned, both gradually in wavelength and reversibly in polarization. Since the kinetics of the “on” and “off” switching can be adjusted by molecular engineering of the dopants and because the photonic cross-communication is selective with respect to the chirality of the incoming light, these photo-responsive microspheres show potential for chiroptical all-optical distributors and switches, in which wavelength, chirality and direction of the reflected light can be controlled independently and reversibly. PMID:26400584

  14. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    PubMed Central

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; De Koninck, Paul

    2016-01-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling. PMID:26857748

  15. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes.

    PubMed

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L; Chekulaev, Dimitri; Canham, Leigh T; Kaplan, Andre

    2016-01-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm(2)). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications. PMID:27440224

  16. All optical fiber combined-imaging system of photoacoustic and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Lee, Byeong Ha

    2016-03-01

    We present an all optical fiber combined-imaging system that integrates non-contact photoacoustic tomography (NPAT) and optical coherence tomography (OCT) to simultaneously provide PA and OCT images. The fiber-based PAT system utilizing a Mach-Zehnder interferometer with a fiber laser of 1550 nm measures the photoacoustic signal at the sample surface. For the generation of a PA signal, a pulse train from a bulk type Nd:YAG laser illuminates the sample via a large core multimode optical fiber. The fiber-based OCT operating at a center wavelength of 1310 nm allowed is combined with the fiber-based PAT system by sharing the same optical fiber probe. The two lights from the fiber laser and the OCT source are guided into the probe through each port of a 2 by 2 optical fiber coupler. The back-reflected lights from the sample are guided to respective imaging systems by the same coupler. With these both NPAT and OCT images could be co-registered without physical contact with the sample. To demonstrate the feasibility of the proposed system, a phantom experiment has been carried out with a phantom composed of a black PET fiber and a fishing wire. The proposed all fiber-optic combined-imaging system has the potential for minimally invasive and improved diagnosis.

  17. Electromagnetically induced transparency in a diamond spin ensemble enables all-optical electromagnetic field sensing.

    PubMed

    Acosta, V M; Jensen, K; Santori, C; Budker, D; Beausoleil, R G

    2013-05-24

    We use electromagnetically induced transparency (EIT) to probe the narrow electron-spin resonance of nitrogen-vacancy centers in diamond. Working with a multipass diamond chip at temperatures 6-30 K, the zero-phonon absorption line (637 nm) exhibits an optical depth of 6 and inhomogeneous linewidth of ~30 GHz FWHM. Simultaneous optical excitation at two frequencies separated by the ground-state zero-field splitting (2.88 GHz) reveals EIT resonances with a contrast exceeding 6% and FWHM down to 0.4 MHz. The resonances provide an all-optical probe of external electric and magnetic fields with a projected photon-shot-noise-limited sensitivity of 0.2 V/cm/√[Hz] and 0.1 nT/√[Hz], respectively. Operation of a prototype diamond-EIT magnetometer measures a noise floor of ~/<1 nT/√[Hz] for frequencies above 10 Hz and Allan deviation of 1.3±1.1 nT for 100 s intervals. The results demonstrate the potential of diamond-EIT devices for applications ranging from quantum-optical memory to precision measurement and tests of fundamental physics. PMID:23745875

  18. Power and length requirements for all-optical switching in semiconductor-doped glass waveguides

    NASA Astrophysics Data System (ADS)

    Mayweather, Derek T.; Digonnet, Michel J. F.; Pantell, Richard H.; Shaw, H. J.

    1994-10-01

    We present a theoretical model that computes the nonlinear index (n2) of semiconductor- doped glasses (SDG), based on the material's properties, and predicts the power and length requirements, as well as the optimum operating wavelengths, for an all-optical SDG waveguide switch. The main conclusions are that (1) n2 depends strongly on pump intensity, which partly explains the large disparity in reported values of n2, (2) the pump and signal wavelengths should be in specific and different ranges to minimize switching power and signal loss, (3) for CdSSe- and CdTe-doped glasses, n2 is relatively small, and the switching power requirement for these two SDGs is consequently quite high (2 - 16 W). We provide evidence that this weak nonlinearity, compared to that of similar semiconductors in bulk, is due to the strong nonradiative recombination of carriers arising from the small size of the semiconductor microcrystallites. Projections indicate that the switching power would be reduced by up to three orders of magnitude by increasing the microcrystallite size, thus producing a slower (ns) but more power-efficient switch.

  19. A matrix based on germanium/ormosil system for all-optical applications

    NASA Astrophysics Data System (ADS)

    Gao, Tianxi; Que, Wenxiu; Wang, Yushu

    2016-05-01

    Germania/ormosil hybrid matrix with large third-order nonlinearity is prepared by a low-temperature sol-gel process. Z-scan measurements indicate that the film fabricated from the pure Germania/ormosil hybrid solution shows an excellent third-order nonlinearity at all measured wavelengths. In order to explore its potential to be a functional matrix, a well-investigated organic dopant disperse red 1 (DR1) azoaromatic chromophore is introduced into the Germania/ormosil system. As a comparison, the poly(methyl methacrylate) (PMMA) polymer is employed and doped with the same content of DR1 molecule. Results indicate that by employing Germania/ormosil matrix system, the figure of merit of DR1-doped material at 532 nm can be greatly improved as compared to that of the PMMA/DR1 polymer film and also other published reports. This improvement helps broaden the limited applications of DR1-doped material and make it acceptable for devices fabrication at 532 nm. Results demonstrate that the as-prepared hybrid matrix might be a promising candidate for all-optical applications.

  20. All-optical modulation in Mid-Wavelength Infrared using porous Si membranes

    PubMed Central

    Park, Sung Jin; Zakar, Ammar; Zerova, Vera L.; Chekulaev, Dimitri; Canham, Leigh T.; Kaplan, Andre

    2016-01-01

    We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 μm. We show that pSi possesses a natural transparency window centred around 4 μm. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm2). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of ~15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications. PMID:27440224

  1. Simultaneous all-optical manipulation and recording of neural circuit activity with cellular resolution in vivo

    PubMed Central

    Packer, Adam M.; Russell, Lloyd E.; Dalgleish, Henry W.P.; Häusser, Michael

    2016-01-01

    We describe an all-optical strategy for simultaneously manipulating and recording the activity of multiple neurons with cellular resolution in vivo. Concurrent two-photon optogenetic activation and calcium imaging is enabled by coexpression of a red-shifted opsin and a genetically encoded calcium indicator. A spatial light modulator allows tens of user-selected neurons to be targeted for spatiotemporally precise optogenetic activation, while simultaneous fast calcium imaging provides high-resolution network-wide readout of the manipulation with negligible optical crosstalk. Proof-of-principle experiments in mouse barrel cortex demonstrate interrogation of the same neuronal population during different behavioral states, and targeting of neuronal ensembles based on their functional signature. This approach extends the optogenetic toolkit beyond the specificity obtained with genetic or viral approaches, enabling high-throughput, flexible and long-term optical interrogation of functionally defined neural circuits with single-cell and single-spike resolution in the mammalian brain in vivo. PMID:25532138

  2. Imaging and detection of early stage dental caries with an all-optical photoacoustic microscope

    NASA Astrophysics Data System (ADS)

    Hughes, D. A.; Sampathkumar, A.; Longbottom, C.; Kirk, K. J.

    2015-01-01

    Tooth decay, at its earliest stages, manifests itself as small, white, subsurface lesions in the enamel. Current methods for detection in the dental clinic are visual and tactile investigations, and bite-wing X-ray radiographs. These techniques suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease due to the small size (<100μm) of the lesion. A fine-resolution (600 nm) ultra-broadband (200 MHz) all-optical photoacoustic microscopy system was is used to image the early signs of tooth decay. Ex-vivo tooth samples exhibiting white spot lesions were scanned and were found to generate a larger (one order of magnitude) photoacoustic (PA) signal in the lesion regions compared to healthy enamel. The high contrast in the PA images potentially allows lesions to be imaged and measured at a much earlier stage than current clinical techniques allow. PA images were cross referenced with histology photographs to validate our experimental results. Our PA system provides a noncontact method for early detection of white-spot lesions with a high detection bandwidth that offers advantages over previously demonstrated ultrasound methods. The technique provides the sensing depth of an ultrasound system, but with the spatial resolution of an optical system.

  3. Continuous all-optical deceleration and single-photon cooling of molecular beams

    NASA Astrophysics Data System (ADS)

    Jayich, A. M.; Vutha, A. C.; Hummon, M. T.; Porto, J. V.; Campbell, W. C.

    2014-02-01

    Ultracold molecular gases are promising as an avenue to rich many-body physics, quantum chemistry, quantum information, and precision measurements. This richness, which flows from the complex internal structure of molecules, makes the creation of ultracold molecular gases using traditional methods (laser plus evaporative cooling) a challenge, in particular due to the spontaneous decay of molecules into dark states. We propose a way to circumvent this key bottleneck using an all-optical method for decelerating molecules using stimulated absorption and emission with a single ultrafast laser. We further describe single-photon cooling of the decelerating molecules that exploits their high dark state pumping rates, turning the principal obstacle to molecular laser cooling into an advantage. Cooling and deceleration may be applied simultaneously and continuously to load molecules into a trap. We discuss implementation details including multilevel numerical simulations of strontium monohydride. These techniques are applicable to a large number of molecular species and atoms with the only requirement being an electric dipole transition that can be accessed with an ultrafast laser.

  4. On the fly all-optical packet switching based on hybrid WDM/OCDMA labeling scheme

    NASA Astrophysics Data System (ADS)

    Brahmi, Houssem; Giannoulis, Giannis; Menif, Mourad; Katopodis, Vasilis; Kalavrouziotis, Dimitrios; Kouloumentas, Christos; Groumas, Panos; Kanakis, Giannis; Stamatiadis, Christos; Avramopoulos, Hercules; Erasme, Didier

    2014-02-01

    We introduce a novel design of an all-optical packet routing node that allows for the selection and forwarding of optical packets based on the routing information contained in hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) labels. A stripping paradigm of optical code-label is adopted. The router is built around an optical-code gate that consists in an optical flip-flop controlled by two fiber Bragg grating correlators and is combined with a Mach-Zehnder interferometer (MZI)-based forwarding gate. We experimentally verify the proof-of-principle operation of the proposed self-routing node under NRZ and OCDMA packet traffic conditions. The successful switching of elastic NRZ payload at 40 Gb/s controlled by DS-OCDMA coded labels and the forwarding operation of encoded data using EQC codes are presented. Proper auto-correlation functions are obtained with higher than 8.1 dB contrast ratio, suitable to efficiently trigger the latching device with a contrast ratio of 11.6 dB and switching times below 3.8 ns. Error-free operation is achieved with 1.5 dB penalty for 40 Gb/s NRZ data and with 2.1 dB penalty for DS-OCDMA packets. The scheme can further be applied to large-scale optical packet switching networks by exploiting efficient optical coders allocated at different WDM channels.

  5. An all-optical Compton source for single-exposure x-ray imaging

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Gautier, J.; Andriyash, I.; Lifschitz, A.; Malka, V.; Rousse, A.; Phuoc, K. Ta

    2016-03-01

    All-optical Compton sources are innovative, compact devices to produce high energy femtosecond x-rays. Here we present results on a single-pulse scheme that uses a plasma mirror to reflect the drive beam of a laser plasma accelerator and to make it collide with the highly-relativistic electrons in its wake. The accelerator is operated in the self-injection regime, producing quasi-monoenergetic electron beams of around 150 MeV peak energy. Scattering with the intense femtosecond laser pulse leads to the emission of a collimated high energy photon beam. Using continuum-attenuation filters we measure significant signal content beyond 100 keV and with simulations we estimate a peak photon energy of around 500 keV. The source divergence is about 13 mrad and the pointing stability is 7 mrad. We demonstrate that the photon yield from the source is sufficiently high to illuminate a centimeter-size sample placed 90 centimeters behind the source, thus obtaining radiographs in a single shot.

  6. Superstructures of chiral nematic microspheres as all-optical switchable distributors of light

    NASA Astrophysics Data System (ADS)

    Aβhoff, Sarah J.; Sukas, Sertan; Yamaguchi, Tadatsugu; Hommersom, Catharina A.; Le Gac, Séverine; Katsonis, Nathalie

    2015-09-01

    Light technology is based on generating, detecting and controlling the wavelength, polarization and direction of light. Emerging applications range from electronics and telecommunication to health, defence and security. In particular, data transmission and communication technologies are currently asking for increasingly complex and fast devices, and therefore there is a growing interest in materials that can be used to transmit light and also to control the distribution of light in space and time. Here, we design chiral nematic microspheres whose shape enables them to reflect light of different wavelengths and handedness in all directions. Assembled in organized hexagonal superstructures, these microspheres of well-defined sizes communicate optically with high selectivity for the colour and chirality of light. Importantly, when the microspheres are doped with photo-responsive molecular switches, their chiroptical communication can be tuned, both gradually in wavelength and reversibly in polarization. Since the kinetics of the “on” and “off” switching can be adjusted by molecular engineering of the dopants and because the photonic cross-communication is selective with respect to the chirality of the incoming light, these photo-responsive microspheres show potential for chiroptical all-optical distributors and switches, in which wavelength, chirality and direction of the reflected light can be controlled independently and reversibly.

  7. Carrier transport in an InGaAs(P)/InP all-optical switching structure

    SciTech Connect

    Knorr, C.; Wilhelm, U.; Ottenwaelder, D.; Scholz, F.; Hangleiter, A.

    1996-12-31

    All-optical switches play a central role in optical computing and optical data processing. SEEDs (self electro-optic effect devices) are one class of devices, which work at low optical power, but need an external electrical feedback. The authors presented a specially designed SCMQW structure, where hole transport is controlled by an additional large heterobarrier. This barrier gives access to steady state escape times by measuring the charge carrier induced field change in the MWQ region. The authors get a minimum value for the hole extraction time over the barrier of several {micro}s at 77 K. At a temperature of 200 K the measured time constants lie below the values, which their rate equation model and the semi-classical model predict, and show a stronger field dependence. This could be accounted for thermally assisted tunneling and contribution of light hole transport, which both reduce the effective barrier height and show a stronger field dependence. Further investigations of the transport times are currently in progress by changing the thickness of the InP barrier and the barrier height of the quaternary material.

  8. All-optical digital 4 × 2 encoder based on 2D photonic crystal ring resonators

    NASA Astrophysics Data System (ADS)

    Moniem, Tamer A.

    2016-04-01

    The photonic crystals draw significant attention to build all-optical logic devices and are considered one of the solutions for the opto-electronic bottleneck via speed and size. The paper presents a novel optical 4 × 2 encoder based on 2D square lattice photonic crystals of silicon rods. The main realization of optical encoder is based on the photonic crystal ring resonator NOR gates. The proposed structure has four logic input ports, two output ports, and two bias input port. The photonic crystal structure has a square lattice of silicon rods with a refractive index of 3.39 in air. The structure has lattice constant 'a' equal to 630 nm and bandgap range from 0.32 to 044. The total size of the proposed 4 × 2 encoder is equal to 35 μm × 35 μm. The simulation results using the dimensional finite difference time domain and Plane Wave Expansion methods confirm the operation and the feasibility of the proposed optical encoder for ultrafast optical digital circuits.

  9. Network connectivity enhancement by exploiting all optical multicast in semiconductor ring laser

    NASA Astrophysics Data System (ADS)

    Siraj, M.; Memon, M. I.; Shoaib, M.; Alshebeili, S.

    2015-03-01

    The use of smart phone and tablet applications will provide the troops for executing, controlling and analyzing sophisticated operations with the commanders providing crucial documents directly to troops wherever and whenever needed. Wireless mesh networks (WMNs) is a cutting edge networking technology which is capable of supporting Joint Tactical radio System (JTRS).WMNs are capable of providing the much needed bandwidth for applications like hand held radios and communication for airborne and ground vehicles. Routing management tasks can be efficiently handled through WMNs through a central command control center. As the spectrum space is congested, cognitive radios are a much welcome technology that will provide much needed bandwidth. They can self-configure themselves, can adapt themselves to the user requirement, provide dynamic spectrum access for minimizing interference and also deliver optimal power output. Sometimes in the indoor environment, there are poor signal issues and reduced coverage. In this paper, a solution utilizing (CR WMNs) over optical network is presented by creating nanocells (PCs) inside the indoor environment. The phenomenon of four-wave mixing (FWM) is exploited to generate all-optical multicast using semiconductor ring laser (SRL). As a result same signal is transmitted at different wavelengths. Every PC is assigned a unique wavelength. By using CR technology in conjunction with PC will not only solve network coverage issue but will provide a good bandwidth to the secondary users.

  10. All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Simin, D.; Soltamov, V. A.; Poshakinskiy, A. V.; Anisimov, A. N.; Babunts, R. A.; Tolmachev, D. O.; Mokhov, E. N.; Trupke, M.; Tarasenko, S. A.; Sperlich, A.; Baranov, P. G.; Dyakonov, V.; Astakhov, G. V.

    2016-07-01

    We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-28SiC) and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3 /2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100 nT /√{Hz } within a volume of 3 ×10-7m m3 at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm3 , the projection noise limit is below 100 fT /√{Hz } .

  11. All-optical frequency downconversion technique utilizing a four-wave mixing effect in a single semiconductor optical amplifier for wavelength division multiplexing radio-over-fiber applications.

    PubMed

    Kim, Hyoung-Jun; Song, Jong-In

    2012-03-26

    An all-optical frequency downconversion utilizing a four-wave mixing effect in a single semiconductor optical amplifier (SOA) was experimentally demonstrated for wavelength division multiplexing (WDM) radio-over-fiber (RoF) applications. Two WDM optical radio frequency (RF) signals having 155 Mbps differential phase shift keying (DPSK) data at 28.5 GHz were simultaneously down-converted to two WDM optical intermediate frequency (IF) signals having an IF frequency of 4.5 GHz by mixing with an optical local oscillator (LO) signal having a LO frequency of 24 GHz in the SOA. The bit-error-rate (BER) performance of the RoF up-links with different optical fiber lengths employing all-optical frequency downconversion was investigated. The receiver sensitivity of the RoF up-link with a 6 km single mode fiber and an optical IF signal in an optical double-sideband format was approximately -8.5 dBm and the power penalty for simultaneous frequency downconversion was approximately 0.63 dB. The BER performance showed a strong dependence on the fiber length due to the fiber dispersion. The receiver sensitivity of the RoF up-link with the optical IF signal in the optical single-sideband format was reduced to approximately -17.4 dBm and showed negligible dependence on the fiber length. PMID:22453476

  12. State of the Art of the all-Optical Radiocarbon Detection (Invited)

    NASA Astrophysics Data System (ADS)

    Cancio Pastor, P.; Mazzotti, D.; Galli, I.; Giusfredi, G.; Bartalini, S.; Cappelli, F.; De Natale, P.

    2013-12-01

    Radiocarbon (14C), the 'natural clock' for dating organic matter, is a very elusive atom. Its present concentration is about one part per trillion. For the past 30 years, accelerator mass spectrometry (AMS) has been adopted as the standard method for detecting such carbon isotope at concentrations well below its natural abundance (3 parts per quadrillion). AMS requires a smaller carbon mass and shorter measurement times than the old standard method of liquid scintillation counting. However, AMS requires huge, expensive and high-maintenance experimental facilities. We have developed a laser spectroscopy technique that is sensitive enough to detect the radiocarbon dioxide molecules at very low concentrations with an all-optical setup that is orders of magnitude more compact and less expensive than AMS [1]. The optical spectroscopy approach is based in the detection of very weak absorption of IR laser light by a 14C-containing molecule as 14C-Carbon Dioxide. Spectroscopic techniques as Cavity Ring Down (CRD) spectroscopy that uses the kilometric absorption paths provided by high-Finesse Fabry-Perot cavities have revolutionized the trace gas detection of molecular species in terms of ultimate sensitivity. Nevertheless CRD has been not capable to detect very elusive molecules as radiocarbon Dioxide. The new developed technique, named SCAR (saturated-absorption cavity ring-down), makes use of molecular absorption saturation to enhance resolution and sensitivity with respect to conventional CRD [2]. By combining SCAR with a frequency-comb-linked CW coherent source, which delivers tunable radiation (around 4.5-μm wavelength) [3], we could set an unprecedented limit in trace gas detection, accessing the part-per-quadrillion concentration range. Comparison between AMS and SCAR techniques to detect 14C by measuring the same carbon samples shows SCAR-based results are currently one order of magnitude shy of challenging AMS, but there is still room for improvement [4

  13. All-Optical Blister Test of Suspended Graphene Using Micro-Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Metten, Dominik; Federspiel, François; Romeo, Michelangelo; Berciaud, Stéphane

    2014-11-01

    We report a comprehensive micro-Raman study of a pressurized suspended graphene membrane that hermetically seals a circular pit, etched in a Si /SiO2 substrate. Placing the sample under a uniform pressure load results in bulging of the graphene membrane and subsequent softening of the main Raman features, due to tensile strain. In such a microcavity, the intensity of the Raman features depends very sensitively on the distance between the graphene membrane and the Si substrate, which acts as the bottom mirror of the cavity. Thus, a spatially resolved analysis of the intensity of the G - and 2 D -mode features as a function of the pressure load permits a direct reconstruction of the blister profile. An average strain is then deduced at each pressure load, and Grüneisen parameters of 1.8 ±0.2 and 2.4 ±0.2 are determined for the Raman G and 2 D modes, respectively. In addition, the measured blister height is proportional to the cubic root of the pressure load, as predicted theoretically. The validation of this scaling provides a direct and accurate determination of the Young's modulus of graphene with a purely optical, hence contactless and minimally invasive, approach. We find a Young's modulus of (1.05 ±0.10 ) TPa for monolayer graphene, in a perfect match with previous nanoindentation measurements. This all-optical methodology opens avenues for pressure sensing using graphene and could readily be adapted to other emerging two-dimensional materials and to nanoresonators.

  14. Novel all-optical planar and compact minimum-stage switches of size >= 4x4

    NASA Astrophysics Data System (ADS)

    Giglmayr, Josef

    1997-01-01

    Throughout the paper, novel all-optical planar 1-stage k multiplied by k-switches and compact minimum-stage k multiplied by k-switches in double-layer and multi-layer technique, are presented and analyzed. In the first case, the number of k(k - 1)/2 switches of size 2 multiplied by 2 (equivalent minimum of the Spanke-Benes network) are arranged in parallel instead of the number of k (equivalent maximum) cascaded 2 multiplied by 2-switches of the Spanke- Benes network. In the second case, the number of 2 multiplied by 2-switches depends on the geometry of the 'pipes' of the switches formed by the layers and waveguides [for a square it is 3k/2(k/2 - 1) for rearrangeable nonblocking and 3(k - 1)k/2(k/2 - 1) for circuit switching networks]. The number of stages (NS) (horizontal cascaded) of the proposed compact switches for the nonblocking interconnection is NS equals n - 1 if the waveguides form an n-gon (n greater than or equal to 3) for any size of the k multiplied by k-switch. In this way, the attenuation of optical signals passing through a photonic network may be minimized. In particular, for any size of a k multiplied by k-switch, dependent on the n-gon, the minimum NS is n-1 equals 2 (triangle) or n - 1 equals 3 (square) etc. Thus the proposed switch concept is of complexity O(1), i.e. the NS is independent of the number of inputs/outputs. Additionally, the proposed switches are capable to operate in the circuit switching mode if and only if (iff) the parallelism increases by the factor k-1.

  15. All-optical control of cardiac excitation: combined high-resolution optogenetic actuation and optical mapping.

    PubMed

    Entcheva, Emilia; Bub, Gil

    2016-05-01

    Cardiac tissue is an excitable system that can support complex spatiotemporal dynamics, including instabilities (arrhythmias) with lethal consequences. While over the last two decades optical mapping of excitation (voltage and calcium dynamics) has facilitated the detailed characterization of such arrhythmia events, until recently, no precise tools existed to actively interrogate cardiac dynamics in space and time. In this work, we discuss the combined use of new methods for space- and time-resolved optogenetic actuation and simultaneous fast, high resolution optical imaging of cardiac excitation waves. First, the mechanisms, limitations and unique features of optically induced responses in cardiomyocytes are outlined. These include the ability to bidirectionally control the membrane potential using depolarizing and hyperpolarizing opsins; the ability to induce prolonged sustained voltage changes; and the ability to control refractoriness and the shape of the cardiac action potential. At the syncytial tissue level, we discuss optogenetically enabled experimentation on cell-cell coupling, alteration of conduction properties and termination of propagating waves by light. Specific attention is given to space- and time-resolved application of optical stimulation using dynamic light patterns to perturb ongoing activation and to probe electrophysiological properties at desired tissue locations. The combined use of optical methods to perturb and to observe the system can offer new tools for precise feedback control of cardiac electrical activity, not available previously with pharmacological and electrical stimulation. These new experimental tools for all-optical electrophysiology allow for a level of precise manipulation and quantification of cardiac dynamics comparable in robustness to the computational setting, and can provide new insights into pacemaking, arrhythmogenesis and suppression or cardioversion. PMID:26857427

  16. All-optical photoacoustic imaging and detection of early-stage dental caries

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Hughes, David A.; Longbottom, Chris; Kirk, Katherine J.

    2015-02-01

    Dental caries remain one of the most common oral diseases in the world. Current detection methods, such as dental explorer and X-ray radiography, suffer from poor sensitivity and specificity at the earliest (and reversible) stages of the disease because of the small size (< 100 microns) of early-stage lesions. We have developed a fine-resolution (480 nm), ultra-broadband (1 GHz), all-optical photoacoustic imaging (AOPAI) system to image and detect early stages of tooth decay. This AOPAI system provides a non-contact, non-invasive and non-ionizing means of detecting early-stage dental caries. Ex-vivo teeth exhibiting early-stage, white-spot lesions were imaged using AOPAI. Experimental scans targeted each early-stage lesion and a reference healthy enamel region. Photoacoustic (PA) signals were generated in the tooth using a 532-nm pulsed laser and the light-induced broadband ultrasound signal was detected at the surface of the tooth with an optical path-stabilized Michelson interferometer operating at 532 nm. The measured time-domain signal was spatially resolved and back-projected to form 2D and 3D maps of the lesion using k-wave reconstruction methods. Experimental data collected from areas of healthy and diseased enamel indicate that the lesion generated a larger PA response compared to healthy enamel. The PA-signal amplitude alone was able to detect a lesion on the surface of the tooth. However, time- reversal reconstructions of the PA scans also quantitatively depicted the depth of the lesion. 3D PA reconstruction of the diseased tooth indicated a sub-surface lesion at a depth of 0.6 mm, in addition to the surface lesion. These results suggest that our AOPAI system is well suited for rapid clinical assessment of early-stage dental caries. An overview of the AOPAI system, fine-resolution PA and histology results of diseased and healthy teeth will be presented.

  17. All-optical quality-of-signal monitoring in real time

    NASA Astrophysics Data System (ADS)

    Anderson, Betty Lise; Abou-Galala, Feras; Rabb, David; Durresi, Arjan

    2003-08-01

    An new optical correlator containing a tapped delay line with thousands of taps is described. This enables ultra-high resolution correlation. We apply this to monitoring quality-of-signal by correlating the received, degraded bits with and un-degraded signal. The strength of the correlation signal, which is all optical, is proportional to the quality. Dispersion and attenuation can be evaluated in less than 100 ps at 40Gb/s, and jitter and noise in less than 100 ns. This is a significant improvement over minutes or even hours for bit-error-rate measurements. Simulations show good correspondence to eye-diagram measurements, the conventional (but slow) way to measure signal quality. If a network node can know the quality of all its links in real-time, it can re-route signals around poor links, and provide restoration and protection as well. The key to all this is an optical correlator with a very large number of taps in its internal tapped delay line. Our device uses a White cell and a fixed micro-mirror array. In a White cell, light bounces back and forth between three spherical mirrors. Multiple beams circulate in the same cell without interfering and are each refocused to a unique pattern of spots. We make the spots land on the micro-mirror array to switch between cells of slightly different lengths. Our current design provides 6550 possible delays for thousands of light beams, using only ten mirrors, a lens, and the micro-mirror array. We have developed two routing and protection protocols to exploit having this real-time information available to the network.

  18. Formation of a Vitamin C Conjugate of Acrolein and its Paraoxonase-mediated Conversion into 5,6,7,8-Tetrahydroxy-4-oxooctanal

    PubMed Central

    Kesinger, Nicholas G.; Langsdorf, Brandi L.; Yokochi, Alexandre F.; Miranda, Cristobal L.; Stevens, Jan F.

    2010-01-01

    Vitamin C (ascorbic acid) has been reported to participate in Michael addition reactions in vitro to form vitamin C conjugates with α,β-unsaturated aldehydes, such as acrolein. This study shows evidence for the formation and metabolism of the vitamin C conjugate of acrolein (AscACR) in cultured human monocytic THP-1 cells exposed to acrolein diacetate. By using 18O and 13C labeling in combination with liquid chromatography–tandem mass spectrometry, AscACR was shown to undergo hydrolytic conversion of the ascorbyl lactone into an intermediate carboxylic acid. Subsequent decarboxylation of the carboxylic acid yielded 5,6,7,8-tetrahydroxy-4-oxooctanal (THO). When THP-1 cells were pretreated with ascorbic acid (1 mM, 18 hours) and then exposed to acrolein diacetate, THO was detected as its pentafluorobenzyl oxime derivative in the cell lysates and medium. Treatment of THP-1 cells with both ascorbic acid and acrolein diacetate was required for THO formation. The formation of THO from AscACR was facilitated by the lactonase enzymes, human recombinant paraoxonases 1 and 2. THP-1 cells exhibited PON activity which explains the catalytic conversion of AscACR into THO in these cells. THO was formed in addition to metabolites of the glutathione conjugate of acrolein, indicating that THO formation contributes to the elimination of acrolein in a cellular environment. PMID:20353174

  19. All-optical photochromic spatial light modulators based on photoinduced electron transfer in rigid matrices

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor); Perry, Joseph W. (Inventor)

    1991-01-01

    A single material (not a multi-element structure) spatial light modulator may be written to, as well as read out from, using light. The device has tailorable rise and hold times dependent on the composition and concentration of the molecular species used as the active components. The spatial resolution of this device is limited only by light diffraction as in volume holograms. The device may function as a two-dimensional mask (transmission or reflection) or as a three-dimensional volume holographic medium. This device, based on optically-induced electron transfer, is able to perform incoherent to coherent image conversion or wavelength conversion over a wide spectral range (ultraviolet, visible, or near-infrared regions).

  20. High speed all-optical PRBS generation using binary phase shift keyed signal based on QD-SOA

    NASA Astrophysics Data System (ADS)

    Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2014-09-01

    A scheme to generate return-to-zero on-off keying (RZ-OOK) high speed all-optical pseudo random bit sequence (PRBS) using binary phase shift keyed (BPSK) signal based on quantum-dot semiconductor optical amplifiers (QD-SOA) has been designed and studied. The PRBS is generated by a linear feedback shift register (LFSR) composed of all-optical logic XOR and AND gates. The XOR gate is composed of a pair of QD SOA Mach-Zehnder interferometers, which can generate BSPK signal to realize all-optical logic XOR gate. Results show that this scheme can mitigate the patterning effects and increase the operation speed to ~250Gb/s.

  1. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    NASA Astrophysics Data System (ADS)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  2. All-optical, polarization-insensitive light tuning properties in silver nanorod arrays covered with photoresponsive liquid crystals.

    PubMed

    Si, Guangyuan; Leong, Eunice S P; Jiang, Xiaoxiao; Lv, Jiangtao; Lin, Jiao; Dai, Haitao; Liu, Yan Jun

    2015-05-28

    Active plasmonics has been an interesting and important topic recently. Here we demonstrate the all-optical, polarization-insensitive tunable manipulation of a hybrid system that integrates a silver nanorod array with photoresponsive liquid crystals. The large-area plasmonic nanorod arrays are fabricated by laser interference lithography and ion milling. By covering a layer of photoresponsive liquid crystals, tunable control of plasmon resonance is achieved under an external light pump. The silver nanorod array also enables the homeotropic alignment of the liquid crystals, which makes the all-optical tuning behavior polarization-insensitive. With its advantages of cost-effective fabrication, easy integration, all-optical control, and polarization-insensitivity, the hybrid system could be valuable in many nanophotonic applications. PMID:25758775

  3. 25th anniversary article: Design of polymethine dyes for all-optical switching applications: guidance from theoretical and computational studies.

    PubMed

    Gieseking, Rebecca L; Mukhopadhyay, Sukrit; Risko, Chad; Marder, Seth R; Brédas, Jean-Luc

    2014-01-01

    All-optical switching--controlling light with light--has the potential to meet the ever-increasing demand for data transmission bandwidth. The development of organic π-conjugated molecular materials with the requisite properties for all-optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π-conjugated materials for all-optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials. PMID:24302357

  4. Burst switching without guard interval in all-optical software-define star intra-data center network

    NASA Astrophysics Data System (ADS)

    Ji, Philip N.; Wang, Ting

    2014-02-01

    Optical switching has been introduced in intra-data center networks (DCNs) to increase capacity and to reduce power consumption. Recently we proposed a star MIMO OFDM-based all-optical DCN with burst switching and software-defined networking. Here, we introduce the control procedure for the star DCN in detail for the first time. The timing, signaling, and operation are described for each step to achieve efficient bandwidth resource utilization. Furthermore, the guidelines for the burst assembling period selection that allows burst switching without guard interval are discussed. The star all-optical DCN offers flexible and efficient control for next-generation data center application.

  5. Photonic-chip-based all-optical ultra-wideband pulse generation via XPM and birefringence in a chalcogenide waveguide.

    PubMed

    Tan, Kang; Marpaung, David; Pant, Ravi; Gao, Feng; Li, Enbang; Wang, Jian; Choi, Duk-Yong; Madden, Steve; Luther-Davies, Barry; Sun, Junqiang; Eggleton, Benjamin J

    2013-01-28

    We report a photonic-chip-based scheme for all-optical ultra-wideband (UWB) pulse generation using a novel all-optical differentiator that exploits cross-phase modulation and birefringence in an As₂S₃ chalcogenide rib waveguide. Polarity-switchable UWB monocycles and doublets were simultaneously obtained with single optical carrier operation. Moreover, transmission over 40-km fiber of the generated UWB doublets is demonstrated with good dispersion tolerance. These results indicate that the proposed approach has potential applications in multi-shape, multi-modulation and long-distance UWB-over-fiber communication systems. PMID:23389181

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

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Singh, Lokendra

    2016-04-01

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

  7. Engineered materials for all-optical helicity-dependent magnetic switching

    NASA Astrophysics Data System (ADS)

    Fullerton, Eric

    2014-03-01

    The possibilities of manipulating magnetization without applied magnetic fields have attracted growing attention over the last fifteen years. The low-power manipulation of magnetization, preferably at ultra-short time scales, has become a fundamental challenge with implications for future magnetic information memory and storage technologies. Here we explore the optical manipulation of the magnetization of engineered materials and devices using 100 fs optical pulses. We demonstrate that all optical - helicity dependent switching (AO-HDS) can be observed not only in selected rare-earth transition-metal (RE-TM) alloy films but also in a much broader variety of materials, including alloys, multilayers, heterostructures and RE-free Co-Ir-based synthetic ferrimagnets. The discovery of AO-HDS in RE-free TM-based synthetic ferrimagnets can enable breakthroughs for numerous applications since it exploits materials that are currently used in magnetic data storage, memories and logic technologies. In addition, this materials study of AO-HDS offers valuable insight into the underlying mechanisms involved. Indeed the common denominator of the diverse structures showing AO-HDS in this study is that two ferromagnetic sub-lattices exhibit magnetization compensation (and therefore angular momentum compensation) at temperatures near or above room temperature. We are highlighting that compensation plays a major role and that this compensation can be established at the atomic level as in alloys but also over a larger nanometers scale as in the multilayers or in heterostructures. We will also discuss the potential to extend AO-HDS to new classes of magnetic materials. This work was done in collaboration with S. Mangin, M. Gottwald, C-H. Lambert, D. Steil, V. Uhlíř, L. Pang, M. Hehn, S. Alebrand, M. Cinchetti, G. Malinowski, Y. Fainman, and M. Aeschlimann. Supported by the ANR-10-BLANC-1005 ``Friends,'' a grant from the Advanced Storage Technology Consortium, Partner University Fund

  8. All-Optical Micro Motors Based on Moving Gratings in Photosensitive Media

    NASA Technical Reports Server (NTRS)

    Curley, M.; Sarkisov, S. S.; Fields, A.; Smith, C.; Kukhtarev, N.; Kulishov, M. B.; Adamovsky, Grigory

    2001-01-01

    An all-optical micromotor with a rotor driven by a traveling wave of surface deformation of a stator being in contact with the rotor is being studied. Instead of an ultrasonic wave produced by an electrically driven piezoelectric actuator as in ultrasonic motors, the wave is a result of a photo-induced surface deformation of a photosensitive material produced by an incident radiation. A thin piezoelectric polymer will deform more easily LiNbO3 or metal when irradiated with light. The type of photosensitive material studied are piezoelectric polymers with and without coatings for connecting electrodes. In order to be considered as a possible candidate for micromotors, the material should exhibit surface deformation produced by a laser beam of the order of 10 microns. This is compared to the deformations produced by static holographic gratings studied in photorefractive crystals of LiNbO3 using high vertical resolution surface profilometer Dektak 3 and surface interferometer WYKO. An experimental setup showing the oscillations has been developed. The setup uses a chopped beam from an Argon ion laser to produce the deformation while a probe beam is reflected by the thin film into a fiber which is then detected on an oscilloscope. A ramp voltage signal generator will drive the piezoelectric film in another experiment to determine the resonance of the film. A current is generated when light is incident upon the film and this current can be measured. The reverse process has already been demonstrated in other piezoelectric actuators. Changing voltage, polarity, and frequency of the signal can easily generate vibrations similar to those when light is incident on the film. This can be compared to the effects of laser interaction with light absorbing fluids such as solutions of 2,9,16,23-Tetrakis(phenylthio)-29H, 31 H-phthalocyanine in chlorobenzene in capillary tubes, The possibility of using a liquid with the piezoelectric film would be a novel idea for a micromotor since

  9. An all-optical frequency up-converter utilizing four-wave mixing in a semiconductor optical amplifier for sub-carrier multiplexed radio-over-fiber applications.

    PubMed

    Kim, Hyoung-Jun; Song, Jong-In; Song, Ho-Jin

    2007-03-19

    A novel all-optical frequency up-converter utilizing four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) was proposed and experimentally demonstrated. The frequency up-converter converted an optical intermediate frequency (IF) signal (f(IF) = 2.5 GHz) to an optical radio frequency (RF) signal (f(RF) = 35 and 40 GHz) through mixing with an optical local oscillator (LO) signal (f(LO) = 37.5 GHz). The up-converter showed positive conversion efficiency of 5.77 dB for the optical IF power of -22 dBm and the optical LO power of -13 dBm. This scheme showed broad bandwidths with respect to both LO and IF frequencies. The up-converter showed a phase noise of -84.5 dBc/Hz for the LO frequency of 37.5 GHz (f(LO)) and the offset frequency of 10 kHz after the frequency up-conversion. PMID:19532579

  10. All-optical sub-ps switching and parallel logic gates with bacteriorhodopsin (BR) protein and BR-gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Yadav, Chandresh

    2014-12-01

    We propose a model for the early sub-picosecond (sub-ps) transitions in the photochromic bacteriorhodopsin (BR) protein photocycle (B570 → H → I460 → J625 → B570) and present a detailed analysis of ultrafast all-optical switching for different pump-probe combinations. BR excitation with 120 fs pump pulses at 570 or 612 nm results in the switching of cw probe beams at 460 and 580 nm exhibiting reverse saturable absorption (RSA) and saturable absorption (SA) respectively. The effect of pump intensity, pump pulse width, lifetime of I460 state, thickness and concentration on switching has been studied in detail. It is shown that low intensity (MW cm-2), high contrast (100%), sub-ps all-optical switching can be achieved with BR-gold nanoparticle solutions. The validity of the proposed model is evident from the good agreement of theoretical simulations with reported experimental results. The switching characteristics have been optimized to design ultrafast all-optical parallel NOT, OR, AND and the universal NOR and NAND logic gates. High contrast, ultrafast switching at relatively lower pump intensities, compared to other organic molecules, opens up exciting prospects for ultrafast, all-optical information processing with BR and BR nano-biophotonic hybrid materials.

  11. Peak-to-average power ratio reduction in all-optical orthogonal frequency division multiplexing system using rotated constellation approach

    NASA Astrophysics Data System (ADS)

    Hmood, Jassim K.; Noordin, Kamarul A.; Arof, Hamzah; Harun, Sulaiman W.

    2015-10-01

    In this paper, a new approach for reducing peak-to-average power ratio (PAPR) based on modulated half subcarriers in all-optical OFDM systems with rotated QAM constellation is presented. To reduce the PAPR, the odd subcarriers are modulated with rotated QAM constellation, while the even subcarriers are modulated with standard QAM constellation. The impact of the rotation angle on the PAPR is mathematically modeled. The effect of PAPR reduction on the system performance is investigated by simulating the all-optical OFDM system, which uses optical coupler-based inverse fast Fourier transform (IFFT)/fast Fourier transform (FFT). The all-optical system is numerically demonstrated with 29 subcarriers. Each subcarrier is modulated by a QAM modulator at a symbol rate of 25 Gsymbol/s. The results reveal that PAPR is reduced with increasing the angle of rotation. The PAPR reduction can reach about 0.8 dB when the complementary cumulative distribution function (CCDF) is 1 × 10-3. Furthermore, both the nonlinear phase noise and the optical signal-to-noise ratio (OSNR) of the system are improved in comparison with the original all-optical OFDM without PAPR reduction.

  12. Alternative approach of developing all-optical Fredkin and Toffoli gates

    NASA Astrophysics Data System (ADS)

    Mandal, Dhoumendra; Mandal, Sumana; Garai, Sisir Kumar

    2015-09-01

    Reversible logic gates show potential roles in communication technology, and it has a wide area of applicability such as in sequential and combinational circuit of optical computing, optical signal processing, multi-valued logic operations, etc. because of its advantageous aspects of data-recovering capabilities, low power consumption, least power dissipation, faster speed of processing, less hardware complexity, etc. In a reversible logic gate not only the outputs can be determined from the inputs, but also the inputs can be uniquely recovered from the outputs. In this article an alternative approach has been made to develop three-input-output Fredkin and Toffoli gates using the frequency conversion property of semiconductor optical amplifier (SOA) and frequency-based beam routing by optical multiplexers and demultiplexers. Simulation results show the feasibility of our proposed scheme.

  13. All-Optical Scheme to Produce Quantum Degenerate Dipolar Molecules in the Vibronic Ground State

    NASA Astrophysics Data System (ADS)

    Mackie, Matt; Debrosse, Catherine

    2010-03-01

    We consider two-color heteronuclear photoassociation of Bose-condensed atoms into dipolar molecules in the J=1 vibronic ground state, where a free-ground laser couples atoms directly to the ground state and a free-bound laser couples the atoms to an electronically-excited state. The addition of the excited state creates a second pathway for creating ground state molecules, leading to quantum interference between direct photoassociation and photoassociation via the excited molecular state, as well as a dispersive-like shift of the free-ground resonance position. Using LiNa as an example, these results are shown to depend on the detuning and intensity of the free-bound laser, as well as the semi-classical size of both molecular states. Despite strong enhancement, coherent conversion to the LiNa vibronic ground state is possible only in a limited regime near the free-bound resonance.

  14. 'Dark' cell formation under protein malnutrition: process of conversion and concept of 'semi-dark' type Purkinje cells.

    PubMed

    James, T J; Sharma, S P; Gupta, S K; Patro, I K

    1992-06-01

    This paper deals with some deleterious effects of protein malnourishment in rat cerebellum. Severe protein deprivation enhanced the formation of 'dark' cells in white rats. It is postulated that abnormal changes in the neuronal contents induced by nutritional stress play a vital role in the formation of the 'dark' cells through an intermediary stage, 'semi-dark' cells. Centrophenoxine a lipofuscinolytic agent, however, seems to interfere with the process of formation of 'dark' cells and/or helps reconversion of the 'dark' cells into the normal or 'light' type Purkinje cells. PMID:1506025

  15. Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate.

    PubMed

    Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge M; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2016-01-01

    CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in carbon dioxide capture and storage (CDCS) facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form; 0∼90 mM) with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs. PMID:27047478

  16. Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate

    PubMed Central

    Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge M.; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2016-01-01

    CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in carbon dioxide capture and storage (CDCS) facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form; 0∼90 mM) with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs. PMID:27047478

  17. Methanol conversion to hydrocarbons over zeolite H-ZSM-5: Investigation of the role of CO and ketene in the formation of the initial C-C bond

    SciTech Connect

    Hutchings, G.J.; Johnston, P. ); Hunter, R. ); Van Rensburg, L.J. )

    1993-08-01

    Mechanistic studies concerning the formation of the initial carbon-carbon bond in the methanol conversion reaction over zeolite H-ZSM-5 are described and discussed. In particular, the possible roles of CO as a reaction intermediate or as a catalyst, via the formation of ketene, are evaluated. Experiments using [sup 13]CH[sub 3]OH/[sup 12]CO reactant mixtures demonstrate that no CO is incorporated into ethene, the primary product of this reaction. In addition, CO is found to have no significant effect on the induction period for this reaction. Model experiments for the methylation of ketene by reaction with Me[sub 2]SO[sub 4] and Me[sub 3]O[sup +]SbCl[sub 6][sup [minus

  18. Single-shot visualization of evolving laser wakefields using an all-optical streak camera

    NASA Astrophysics Data System (ADS)

    Li, Zhengyan; Tsai, Hai-En; Zhang, Xi; Pai, Chih-Hao; Chang, Yen-Yu; Zgadzaj, Rafal; Wang, Xiaoming; Khudik, Vladimir; Shvets, Gennady; Downer, Michael

    2014-10-01

    We visualize ps-time-scale evolution of an electron density bubble, a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse, from the phase ``streak'' that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometry, reveal formation, propagation and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell (PIC) simulations validate the observed density-dependent bubble evolution, and correlate it with generation of a quasi-monoenergetic ~100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at plasma density ne ~2e19 cm-3, at which the bubble formed and persisted until the jet exit, enabling acceleration over a distance slightly exceeding the dephasing length. In contrast, at lower density, electrons accelerated inefficiently due to weak laser self-focusing and late bubble formation. At higher density, overly strong self-focusing also led to low quality electrons due to early bubble formation and strong dephasing. Bubble coalescence due to beam loading further degraded electron acceleration. This work was supported by DOE grants DESC0011617 and DE-SC0007889 and by the NSF-DOE Partnership in Plasma Science program.

  19. Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

    PubMed

    Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

    2015-06-01

    The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation. PMID:25978089

  20. All-optical investigation of tunable picosecond magnetization dynamics in ferromagnetic nanostripes with a width down to 50 nm.

    PubMed

    Saha, Susmita; Barman, Saswati; Otani, YoshiChika; Barman, Anjan

    2015-11-21

    Ferromagnetic nanostripes are important elements for a number of interesting technologies including magnetic racetrack memory, spin logic and magnonics. Understanding and controlling magnetization dynamics in such nanostripes are hence important problems in nanoscience and technology. Here we present an all-optical excitation and detection of ultrafast magnetization dynamics, including spin waves, in 5 μm long Ni80Fe20 nanostripes with varying stripe widths from 200 nm down to 50 nm. We observed a strong width dependent variation in the frequency, anisotropy and the spatial nature of spin waves in these systems. The effect of inter-stripe interaction is also studied and the 50 nm wide stripe is found to be nearly magnetostatically isolated, allowing us to detect the dynamics of a 50 nm wide individual stripe using an all-optical measurement technique. The tunability in magnetization dynamics with stripe widths is important for their applications in various spin based technologies. PMID:26488800

  1. Demonstration of all-optical two bit digital comparator using self-locked Fabry-Perot laser diode

    NASA Astrophysics Data System (ADS)

    Nakarmi, Bikash; Rakib-Uddin, M.; Won, Yong Hyub

    2012-02-01

    All-optical two bit digital comparator using single mode Fabry-Perot laser diodes (SMFP-LDs) is proposed and demonstrated with 10 Gbps PRBS signal of 231-1. Digital comparators are one of the important components for decision making circuits, threshold detection, which are used in optical signal processing and optical computing. The basic principle of the comparator is based on injection locking, multi-input injection locking and combinational input injection locking (CMIL) to realize the greater than, less than, and equal to function of the basic comparator circuit. These principles are used to realize the different optical logic gates which are combined together to demonstrate optical comparator with the minimum number of components, making the configuration cheaper and simpler. The proposed method draws less current and hence power effective too. Output waveform diagram and output eye diagram for all three cases of comparator are presented to verify all functions of all-optical comparator.

  2. Microdisk resonator assisted all-optical switching with improved speed using a reverse-biased p-n diode

    NASA Astrophysics Data System (ADS)

    Xie, Jingya; Zhou, Linjie; Li, Xinwan; Chen, Jianping

    2015-05-01

    We present a compact and power efficient all-optical switching using a silicon microdisk resonator integrated with a p-n junction. We study the dependence of free-carrier lifetime, one of the most critical parameters to determine the switching speed, on reverse bias, optical intensity, and p-n junction position and dimension. Our experiments reveal that the carrier lifetime decreases with the increasing reverse bias, consistent with the theoretical results. The all-optical switching of a 211-1 non-return-to-zero pseudo-random binary sequence (PRBS) signal at a data rate of 10 Gbits/s is demonstrated with p-n junction reversely biased at -15 V and the pump power being 5.96 dBm.

  3. Routing and wavelength assignment algorithms for all-optical WDM networks based on virtual multiple self-healing ring architecture

    NASA Astrophysics Data System (ADS)

    Ishikawa, Akio; Kishi, Yoji

    2000-09-01

    This paper newly proposes a self-healing architecture in all- optical WDM networks based on virtual embedded multiple rings (Virtual Multiple Self Healing Rings: VM-SHR). Focusing upon the network design aspect of the proposed architecture, this paper describes design methodologies for VM-SHR networks. For two major problems in all-optical WDM network design, that is, the connection routing and wavelength assignment problems, we first established solution models based on mathematical programming formulation, each of which can be solved by common integer programming algorithms, respectively. In addition, we also developed an efficient heuristic algorithm for the wavelength assignment problem. Their usefulness and performance are demonstrated through the extensive simulation results.

  4. All-optical investigation of tunable picosecond magnetization dynamics in ferromagnetic nanostripes with a width down to 50 nm

    NASA Astrophysics Data System (ADS)

    Saha, Susmita; Barman, Saswati; Otani, Yoshichika; Barman, Anjan

    2015-10-01

    Ferromagnetic nanostripes are important elements for a number of interesting technologies including magnetic racetrack memory, spin logic and magnonics. Understanding and controlling magnetization dynamics in such nanostripes are hence important problems in nanoscience and technology. Here we present an all-optical excitation and detection of ultrafast magnetization dynamics, including spin waves, in 5 μm long Ni80Fe20 nanostripes with varying stripe widths from 200 nm down to 50 nm. We observed a strong width dependent variation in the frequency, anisotropy and the spatial nature of spin waves in these systems. The effect of inter-stripe interaction is also studied and the 50 nm wide stripe is found to be nearly magnetostatically isolated, allowing us to detect the dynamics of a 50 nm wide individual stripe using an all-optical measurement technique. The tunability in magnetization dynamics with stripe widths is important for their applications in various spin based technologies.

  5. Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique

    PubMed Central

    Phing, Sze Ho; Mazhorova, Anna; Shalaby, Mostafa; Peccianti, Marco; Clerici, Matteo; Pasquazi, Alessia; Ozturk, Yavuz; Ali, Jalil; Morandotti, Roberto

    2015-01-01

    Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane. PMID:25711343

  6. Time-resolved chirp properties of semiconductor optical amplifiers in high-speed all-optical switches

    NASA Astrophysics Data System (ADS)

    Chen, Ligong; Lu, Rongguo; Zhang, Shangjian; Li, Jianfeng; Liu, Yong

    2013-03-01

    The chirp properties of semiconductor optical amplifiers in all-optical switches are numerically investigated using a field propagation model. The chirp dynamics in the blue-shift and red-shift sideband are analyzed under the injection of random optical pump pulses. We also analyze the impact of the blue-detuned filtering scheme that is used to eliminate the pattern effect and enhance the operating speed of the optical switching. The reason for overshoots in eye diagrams in the blue-detuned filtering scheme is explained. We find that overshoots result from the ultrafast blue chirp induced by carrier heating and two-phonon absorption. These results are very useful for semiconductor optical amplifier-based ultrafast all-optical signal processing.

  7. All-optical transistors and logic gates using a parity-time-symmetric Y-junction: Design and simulation

    SciTech Connect

    Ding, Shulin; Wang, Guo Ping

    2015-09-28

    Classical nonlinear or quantum all-optical transistors are dependent on the value of input signal intensity or need extra co-propagating beams. In this paper, we present a kind of all-optical transistors constructed with parity-time (PT)-symmetric Y-junctions, which perform independently on the value of signal intensity in an unsaturated gain case and can also work after introducing saturated gain. Further, we show that control signal can switch the device from amplification of peaks in time to transformation of peaks to amplified troughs. By using these PT-symmetric Y-junctions with currently available materials and technologies, we can implement interesting logic functions such as NOT and XOR (exclusive OR) gates, implying potential applications of such structures in designing optical logic gates, optical switches, and signal transformations or amplifications.

  8. All-Optical Preparation of Coherent Dark States of a Single Rare Earth Ion Spin in a Crystal

    NASA Astrophysics Data System (ADS)

    Xia, Kangwei; Kolesov, Roman; Wang, Ya; Siyushev, Petr; Reuter, Rolf; Kornher, Thomas; Kukharchyk, Nadezhda; Wieck, Andreas D.; Villa, Bruno; Yang, Sen; Wrachtrup, Jörg

    2015-08-01

    All-optical addressing and coherent control of single solid-state based quantum bits is a key tool for fast and precise control of ground-state spin qubits. So far, all-optical addressing of qubits was demonstrated only in a very few systems, such as color centers and quantum dots. Here, we perform high-resolution spectroscopic of native and implanted single rare earth ions in solid, namely, a cerium ion in yttrium aluminum garnet (YAG) crystal. We find narrow and spectrally stable optical transitions between the spin sublevels of the ground and excited optical states. Utilizing these transitions we demonstrate the generation of a coherent dark state in electron spin sublevels of a single Ce3 + ion in YAG by coherent population trapping.

  9. Implementation of all-optical reversible logic gate based on holographic laser induced grating using azo-dye doped polymers

    NASA Astrophysics Data System (ADS)

    Forsati, Rana; Valipour Ebrahimi, Sara; Navi, Keivan; Mohajerani, Ezeddin; Jashnsaz, Hossein

    2013-02-01

    Increasing demand for power reduction in computer systems has led to new trends in computations and computer design including reversible computing. Its main aim is to eliminate power dissipation in logical elements but can have some other advantages such as data security and error prevention. Because of interesting properties of reversible computing, implementing computing devices with reversible manner is the only way to make the reversible computing a reality. In recent years, reversible logic has turned out to be a promising computing paradigm having application in CMOS, nanotechnology, quantum computing and optical computing. In this paper, we propose and realize a novel implementation of Toffoli gate in all-optical domain. We have explained its principle of operations and described an actual experimental implementation. The all-optical reversible gate presented in this paper will be useful in different applications such as arithmetic and logical operations in the domain of reversible logic-based computing.

  10. Theoretical study of the all-optical tunable rainbow-trapping-like effect in chirped plasmonic slot waveguides

    NASA Astrophysics Data System (ADS)

    Zhu, Yu; Hu, Xiaoyong; Gong, Qihuang

    2013-03-01

    An all-optical tunable rainbow-trapping-like effect is realized theoretically in a plasmonic slot waveguide with a chirped nanograting, permeated with organic polymer made of poly(hexafluoropropylene oxide) doped with cholesteryl iodide. Gradually increasing the grating period ensures that the stop band edge of the surface plasmon polariton mode varies with position along the nanograting, which brings about the rainbow-trapping-like effect. The physical mechanism underlying the all-optical tunability of this effect is attributed to the variation in the dispersion relations of the surface plasmon polariton mode caused by the pump laser induced refractive index change of cholesteryl iodide. A shift of up to 17 μm in the trapped position of the surface plasmon polariton mode is achieved under excitation of a 450 mJ cm-2 pump laser.

  11. On the suitability of fibre optical parametric amplifiers for use in all-optical agile photonic networks

    NASA Astrophysics Data System (ADS)

    Gryspolakis, Nikolaos

    B. Next, we introduce modulated channels to the amplifier in order to compare their effect on the Bit Error Rate (BER) performance. We consider the impact on FOPAs when employing different modulation formats, such as RZ, NRZ and RZ-DPSK. Carefully selected modulation formats can improve BER performance and reduce the effects of cross-phase modulation, four wave mixing (FWM) products generation or dispersion (non-linear and linear inter-channel interference). Especially for the case of FOPAs, because of the ultra-fast interaction times of the FWM phenomenon, cross gain modulation can be a great deterrent for using FOPAs. We use RZ-DPSK in order to suppress the WDM signal crosstalk. Only by using RZ-DPSK, we obtain an improved receiver sensitivity of 5 dB when operating at 40 Gb/s. Finally, we investigate ways to mitigate such effects as the ones described above (gain excursions, gain tilt, etc.). We demonstrate that by using a ring configuration with optical feedback for the first time in FOPAs, we can achieve all-optical gain clamping (AOGC), mitigating gain excursions and attaining gain, independent of channel input power for a large range of PCIP. For example, with the use of AOGC, we reduce the add/drop-induced gain excursions from 4 dB to 0.6 dB. Also, by the combined use of AOGC and RZ-DPSK, we mitigate most of the aforementioned hindrances described above.

  12. Modulation-enabled tapered remote coupler: all-optical communication on and off chip

    NASA Astrophysics Data System (ADS)

    Gu, Tian; Nair, Rohit; Haney, Michael W.

    2010-02-01

    The "Modulation-Enabled Tapered Remote Coupler" (METRoC) is introduced targeting the integration of on-chip and off-chip optical interconnects. With Moore's law scaling of CMOS critical dimensions, the computing power of modern microprocessors has grown rapidly. Future multi-core chips will demand aggregate on- and off-chip bandwidths in the TBytes/sec regime. However, metal on-chip global interconnections and off-chip communications do not scale commensurately with the CMOS device sizes, resulting in challenges to meet the growing bandwidth requirements within acceptable power budgets. Optics is a potential solution to replace the fundamentally limited electrical interconnects. Recent advancements in optical and optoelectronic component fabrication and manufacturing processes may enable implementation of optical interconnects at the chip-scale. An optical solution that seamlessly integrates the two domains is highly desirable. The METRoC is proposed as a compact optical interconnect fabric that obviates the need for opto-electronic and electrooptic conversions when signals propagate between the on-chip and off-chip domains. Multiple quantum well (MQW) devices are chosen as the optical modulators and photodetectors. The key aspect of METRoC is the modulationenhanced prismatic structures embedded in waveguides, which enable the direct coupling from the integrated MQW devices to the intra-chip guided-wave fabrics. Additionally, tapered remote couplers can provide free-space interconnections between chips or remote regions on-chip. Both coupling structures have small footprint areas and hence are projected to provide high bandwidth densities. The fabrication process is compatible with silicon CMOS processes. The coupling fabric can also be used to optically interconnect two silicon die within a multichip module.

  13. Improving Recording Density of All-Optical Magnetic Storage by Using High-Pass Angular Spectrum Filters

    NASA Astrophysics Data System (ADS)

    Zhuang, You-Yi; Zhang, Yao-Ju

    2009-10-01

    A new design is presented to improve the magnetic recording density in all-optical magnetic storage. By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy. Magnetization of the film is induced by the inverse Faraday effect. As the obstructed angle of the filter increases the magnetic recording density increases evidently. The magnetization intensity and the sidelobe effect are also discussed.

  14. On the size-dependent magnetism and all-optical magnetization switching of transition-metal silicide nanostructures

    SciTech Connect

    Glushkov, G. I.; Tuchin, A. V.; Popov, S. V.; Bityutskaya, L. A.

    2015-12-15

    Theoretical investigations of the electronic structure, synthesis, and all-optical magnetization switching of transition-metal silicide nanostructures are reported. The magnetic moment of the nanostructures is studied as a function of the silicide cluster size and configuration. The experimentally demonstrated magnetization switching of nanostructured nickel silicide by circularly polarized light makes it possible to create high-speed storage devices with high density data recording.

  15. All-optical cross-bar network architecture using TOAD based interferometric switch and designing of reconfigurable logic unit

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanay

    2011-12-01

    The design of all-optical 2 × 2 Terahertz Optical Asymmetric Demultiplexer (TOAD) based interferometric switch is proposed and described in this manuscript. Numerical simulation has been done to achieve the performance of the switch. Using this 2 × 2 TOAD based switch, cross-bar network architecture is designed. A reconfigurable logic unit is also proposed in this manuscript, which can perform 16-Boolean logical operations.

  16. Multi-format receiver for non-return-to-zero binary-phase-shift-keyed and non-return-to-zero amplitude-shit-keyed signals.

    PubMed

    Liu, Zhixin; Xiao, Shilin; Cai, Lei; Liang, Zheng

    2009-02-16

    A Multi-format receiver for both non-return-to-zero binary-phase- shift-keyed (NRZ-BPSK) signal and non-return-to-zero amplitude-shift- keyed (NRZ-ASK) signal is demonstrated. Multi-format signal detection is based on incoherent BPSK demodulation and ASK-BPSK format conversion. Incoherent BPSK demodulation is realized by a Mach- Zehnder delay interferometer (MZDI) and a feedback decoder. Transmission experiments validate the feasibility of multi-format receiver. This receiver has potential to serve as a useful terminal block for all-optical wavelength division-multiplexed (WDM) networks. PMID:19219195

  17. Low timing jitter 40 Gb/s all-optical clock recovery based on an amplified feedback laser diode

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Qiu, Jifang; Zhao, Lingjuan; Wu, Jian; Lou, Caiyun; Wang, Wei

    2012-06-01

    We demonstrate 40 Gb/s all-optical clock recovery by using a monolithic integrated amplified-feedback laser (AFL) with coherent injection-locked method. The AFL consists of a gain-coupled DFB laser and an optical amplified feedback external cavity. With proper design and operation of AFL, the device can work at self-pulsation state that resulted from the beating between two lasing modes. The self-pulsation can be injection-locked to the optical clock embedded in input data streams. Due to different work mechanisms, there are two all-optical clock recovery operation modes: incoherent injection-locked and coherent injection-locked. It's predicted that the coherent injection method has various advantages: 1) requiring low injection power recovery, 2) independent of the bit rate and 3) introducing little timing jitter to the recovered clock. The robustness of coherent clock recovery is confirmed by our experimental results. We set up a return-to- zero (RZ) pseudorandom binary sequence (PRBS) data streams all-optical clock recovery system. This coherent injection-locked based clock recovery method is optical signal noise ratio (OSNR) and chromatic dispersion (CD) degeneration tolerant, and has low timing jitter and high sensitivity.

  18. OptoDyCE as an automated system for high-throughput all-optical dynamic cardiac electrophysiology

    PubMed Central

    Klimas, Aleksandra; Ambrosi, Christina M.; Yu, Jinzhu; Williams, John C.; Bien, Harold; Entcheva, Emilia

    2016-01-01

    The improvement of preclinical cardiotoxicity testing, discovery of new ion-channel-targeted drugs, and phenotyping and use of stem cell-derived cardiomyocytes and other biologics all necessitate high-throughput (HT), cellular-level electrophysiological interrogation tools. Optical techniques for actuation and sensing provide instant parallelism, enabling contactless dynamic HT testing of cells and small-tissue constructs, not affordable by other means. Here we show, computationally and experimentally, the limits of all-optical electrophysiology when applied to drug testing, then implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We validate optical actuation by virally introducing optogenetic drivers in rat and human cardiomyocytes or through the modular use of dedicated light-sensitive somatic ‘spark' cells. We show that this automated all-optical approach provides HT means of cellular interrogation, that is, allows for dynamic testing of >600 multicellular samples or compounds per hour, and yields high-content information about the action of a drug over time, space and doses. PMID:27161419

  19. OptoDyCE as an automated system for high-throughput all-optical dynamic cardiac electrophysiology.

    PubMed

    Klimas, Aleksandra; Ambrosi, Christina M; Yu, Jinzhu; Williams, John C; Bien, Harold; Entcheva, Emilia

    2016-01-01

    The improvement of preclinical cardiotoxicity testing, discovery of new ion-channel-targeted drugs, and phenotyping and use of stem cell-derived cardiomyocytes and other biologics all necessitate high-throughput (HT), cellular-level electrophysiological interrogation tools. Optical techniques for actuation and sensing provide instant parallelism, enabling contactless dynamic HT testing of cells and small-tissue constructs, not affordable by other means. Here we show, computationally and experimentally, the limits of all-optical electrophysiology when applied to drug testing, then implement and validate OptoDyCE, a fully automated system for all-optical cardiac electrophysiology. We validate optical actuation by virally introducing optogenetic drivers in rat and human cardiomyocytes or through the modular use of dedicated light-sensitive somatic 'spark' cells. We show that this automated all-optical approach provides HT means of cellular interrogation, that is, allows for dynamic testing of >600 multicellular samples or compounds per hour, and yields high-content information about the action of a drug over time, space and doses. PMID:27161419

  20. Single-shot visualization of evolving laser wakefields using an all-optical streak camera.

    PubMed

    Li, Zhengyan; Tsai, Hai-En; Zhang, Xi; Pai, Chih-Hao; Chang, Yen-Yu; Zgadzaj, Rafal; Wang, Xiaoming; Khudik, V; Shvets, G; Downer, M C

    2014-08-22

    We visualize ps-time-scale evolution of an electron density bubble--a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse--from the phase "streak" that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometric techniques, reveal the formation, propagation, and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell simulations validate the observed density-dependent bubble evolution, and correlate it with the generation of a quasimonoenergetic ∼ 100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at a plasma density n(e) ≈ 2 × 10(19) cm(-3), inefficient acceleration at lower density, and dephasing limits at higher density. PMID:25192102

  1. Conversion of biomass-derived levulinate and formate esters into γ-valerolactone over supported gold catalysts.

    PubMed

    Du, Xian-Long; Bi, Qing-Yuan; Liu, Yong-Mei; Cao, Yong; Fan, Kang-Nian

    2011-12-16

    The utilization of biomass has recently attracted tremendous attention as a potential alternative to petroleum for the production of liquid fuels and chemicals. We report an efficient alcohol-mediated reactive extraction strategy by which a hydrophobic mixture of butyl levulinate and formate esters, derived from cellulosic biomass, can be converted to valuable γ-valerolactone (GVL) by a simple supported gold catalyst system without need of an external hydrogen source. The essential role of the supported gold is to facilitate the rapid and selective decomposition of butyl formate to produce a hydrogen stream, which enables the highly effective reduction of butyl levulinate into GVL. This protocol simplifies the recovery and recycling of sulfuric acid, which is used for cellulose deconstruction. PMID:22105964

  2. Electrochemical conversion of carbon dioxide to methanol with the assistance of formate dehydrogenase and methanol dehydrogenase as biocatalysts

    SciTech Connect

    Kuwabata, Susumu; Tsuda, Ryo; Yoneyama, Hiroshi )

    1994-06-15

    Electrolysis at potentials between -0.7 and -0.9 V vs SCE of carbon dioxide-saturated phosphate buffer solutions (pH7) containing formate dehydrogenase (FDH) and either methyl viologen (MV[sup 2+]) or pyrroloquinolinequinone (PQQ) as an electron mediator yielded formate with current efficiencies as high as 90%. The enzyme was durable as long as the electrolysis was carried out in the dark. Electrolysis of phosphate buffer solutions containing sodium formate in the presence of methanol dehydrogenase (MDH) and MV[sup 2+] at -0.7 V vs SCE yielded formaldehyde if the concentration of the enzyme used was low, whereas both formaldehyde and methanol were produced for relatively high concentrations of the enzyme where the methanol production began to occur when the formaldehyde produced accumulated. The use of PQQ in place of MV[sup 2+] as the electron mediator exclusively produced methanol alone after some induction period in the electrolysis. On the basis of these results, successful attempts have been made to reduce carbon dioxide to methanol with cooperative assistance of FDH and MDH in the presence of PQQ as the electron mediator. The role of enzyme and mediator in these reduction processes is discussed in detail. 34 refs., 10 figs., 2 tabs.

  3. Voice Prosthetic Biofilm Formation and Candida Morphogenic Conversions in Absence and Presence of Different Bacterial Strains and Species on Silicone-Rubber

    PubMed Central

    van der Mei, Henny C.; Buijssen, Kevin J. D. A.; van der Laan, Bernard F. A. M.; Ovchinnikova, Ekatarina; Geertsema-Doornbusch, Gésinda I.; Atema-Smit, Jelly; van de Belt-Gritter, Betsy; Busscher, Henk J.

    2014-01-01

    Morphogenic conversion of Candida from a yeast to hyphal morphology plays a pivotal role in the pathogenicity of Candida species. Both Candida albicans and Candida tropicalis, in combination with a variety of different bacterial strains and species, appear in biofilms on silicone-rubber voice prostheses used in laryngectomized patients. Here we study biofilm formation on silicone-rubber by C. albicans or C. tropicalis in combination with different commensal bacterial strains and lactobacillus strains. In addition, hyphal formation in C. albicans and C. tropicalis, as stimulated by Rothia dentocariosa and lactobacilli was evaluated, as clinical studies outlined that these bacterial strains have opposite results on the clinical life-time of silicone-rubber voice prostheses. Biofilms were grown during eight days in a silicone-rubber tube, while passing the biofilms through episodes of nutritional feast and famine. Biofilms consisting of combinations of C. albicans and a bacterial strain comprised significantly less viable organisms than combinations comprising C. tropicalis. High percentages of Candida were found in biofilms grown in combination with lactobacilli. Interestingly, L. casei, with demonstrated favorable effects on the clinical life-time of voice prostheses, reduced the percentage hyphal formation in Candida biofilms as compared with Candida biofilms grown in absence of bacteria or grown in combination with R. dentocariosa, a bacterial strain whose presence is associated with short clinical life-times of voice prostheses. PMID:25111806

  4. Cu-catalyzed conversion of propargyl acetates to E-α,β-unsaturated amides via ketenimine formation with sulfonyl azides.

    PubMed

    Kumar, Yalla Kiran; Ranjith Kumar, Gadi; Reddy, Maddi Sridhar

    2014-01-17

    The reaction between readily accessible propargyl acetates and sulfonyl azides in the presence of CuI catalyst yields trans-α,β-unsaturated N-tosylamides via N-sulfonyl ketenimine formation followed by a probable 1,3-OAc migration ([3,3]-sigmatropic rearrangement). The reaction is very general, allowing all kinds of substitution, including alkyl, aryl (electron-donating, -withdrawing, and -neutral), heteroaryl, and vinyl groups, on the C-terminal of acrylamide. Also, the method affords the products at ambient temperature with excellent diastereoselectivity in moderate to good yields. PMID:24344764

  5. On the design of reconfigurable ultrafast all-optical NOR and NAND gates using a single quantum-dot semiconductor optical amplifier-based Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Dimitriadou, E.; Zoiros, K. E.

    2012-10-01

    The feasibility of implementing reconfigurable ultrafast all-optical NOR and NAND gates by employing a single Mach-Zehnder interferometer (MZI) with quantum-dot semiconductor optical amplifiers (QD-SOAs) is theoretically investigated. The reconfiguration of the scheme that allows conversion from one gate to the other is achieved by simply turning on or off a clock signal, while the complement of one of the data signals is used too as input for both gates. By conducting a numerical simulation, the conditions under which the QD-SOA-based MZI must be adjusted to operate so as to simultaneously ensure an acceptable extinction ratio for the NOR and amplitude modulation for the NAND are specified. This procedure is more demanding than when each gate is considered separately. Nevertheless it is possible to extract technologically realistic and achievable guidelines for the data signals and QD-SOAs characteristics in order for these gates to be jointly designed without modifying the fundamental structure or data driving mode of the MZI switch. In this manner a permissible range and a proper selection of values for the critical performance parameters that is common for these universal logic gates is derived, which enables both of them to be realized with a logically correct and high quality outcome.

  6. All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient ( d n / d T ) measurements

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Fairchild, Steven B.; Arends, Armando A.; Urbas, Augustine M.

    2016-05-01

    This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity ( Λ) and thermo-optic coefficient ( d n / d T ) of materials that are absorbing at λ = 10.6 μm and are transparent to semi-transparent at λ = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and d n / d T properties ranging between 0.7 W/m K ≲ Λ ≲ 33.5 W/m K and -12 × 10-6 K-1 ≲ d n / d T ≲ 14 × 10-6 K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.

  7. Design and analysis of polarization independent all-optical logic gates in silicon-on-insulator photonic crystal

    NASA Astrophysics Data System (ADS)

    Rani, Preeti; Kalra, Yogita; Sinha, R. K.

    2016-09-01

    In this paper, we have reported design and analysis of polarization independent all optical logic gates in silicon-on-insulator photonic crystal consisting of two dimensional honeycomb lattices with two different air holes exhibiting photonic band gap for both TE and TM mode in the optical communication window. The proposed structures perform as an AND optical logic gate and all the optical logic gates based on the phenomenon of interference. The response period and bit rate for TE and TM polarizations at a wavelength of 1.55 μm show improved results as reported earlier.

  8. All-optical controllable channel-drop filters in two-dimensional square-lattice photonic crystals

    NASA Astrophysics Data System (ADS)

    Fasihi, K.

    2016-05-01

    A novel all-optical controllable channel-drop filter in photonic crystals (PC) of square lattice is presented. We show that using a resonant-cavity-based add-drop filter with a wavelength-selective reflection feedback and a single-control switching module which is based on nonlinear PC microcavities, the dropped channel can be routed to the drop port or returned to the bus waveguide. Using the temporal coupled-mode theory and two-dimensional nonlinear finite-difference time-domain method, the performance of the proposed device is investigated and the simulation results show the validity of the proposed design.

  9. High-speed all-optical NAND/AND logic gates using four-wave mixing Bragg scattering.

    PubMed

    Li, Kangmei; Ting, Hong-Fu; Foster, Mark A; Foster, Amy C

    2016-07-15

    A high-speed all-optical NAND logic gate is proposed and experimentally demonstrated using four-wave mixing Bragg scattering in highly nonlinear fiber. NAND/AND logic functions are implemented at two wavelengths by encoding logic inputs on two pumps via on-off keying. A 15.2-dB depletion of the signal is obtained for NAND operation, and time domain measurements show 10-Gb/s NAND/AND logic operations with open eye diagrams. The approach can be readily extended to higher data rates and transferred to on-chip waveguide platforms. PMID:27420525

  10. All-optical packet header and payload separation based on two TOADs for optical packet switched networks

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zhang, Min; Ye, Peida

    2006-09-01

    We present a novel all-optical header and payload separation technique that can be utilized in Un-Slotted optical packet switched networks. The technique uses two modified TOADs, one is for packet header extraction with differential modulation scheme and the other performs a simple XOR operation between the packet and its self-derived header to get the separated payload. The main virtue of this system is simple structure and low power consumption. Through numerical simulations, the operating characteristics of the scheme are illustrated. In addition, the system parameters are discussed and designed to optimize the performance of the proposed scheme.

  11. Nonlinear long-period gratings in As2Se3 chalcogenide fiber for all-optical switching

    NASA Astrophysics Data System (ADS)

    Nguyen, H. C.; Yeom, D.-I.; Mägi, E. C.; Fu, L. B.; Kuhlmey, B. T.; Martijn de Sterke, C.; Eggleton, B. J.

    2008-03-01

    We present experimental demonstration of all-optical switching using long-period gratings (LPGs) in highly nonlinear As2Se3 chalcogenide fiber. We use a 135mm grating which is generated using acoustic waves. We characterize the nonlinear pulse propagation through the LPG using picosecond pulses tuned to different wavelengths with respect to the grating resonance. We compare the results with numerical simulations and observe switching at pulse peak powers around 50W, two orders of magnitude smaller than previously demonstrated in silica.

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

    PubMed

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

    2006-06-20

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

  13. All-optical switching with 1-ps response time in a DDMEBT enabled silicon grating coupler/resonator hybrid device.

    PubMed

    Covey, John; Finke, Aaron D; Xu, Xiaochuan; Wu, Wenzhi; Wang, Yaguo; Diederich, François; Chen, Ray T

    2014-10-01

    An amorphous film of the third-order nonlinear optical material DDMEBT was spun onto silicon chips for the first time, filling 80 nm lithographic features. A 710 μm² device was designed, fabricated, and tested that acts both as a nonlinear resonator switch and as an input/output grating coupler to a perfectly vertical single mode fiber. Autocorrelation and spectral measurements indicate the device has <1 ps response time, 4 nm of switching bandwidth, and 4 dB of on/off contrast. With sufficient power, this all-optical device can potentially modulate a single optical carrier frequency in excess of 1 THz. PMID:25322028

  14. Properties of an ultrafast all-optical switching window in an integrated silicon-based Mach - Zehnder interferometer

    SciTech Connect

    Wu Jianwei; Luo Fengguang; Yu Zhihua; Tao Qing

    2009-03-31

    An ultrafast all-optical switch based on the integrated Mach - Zehnder interferometer (MZI) with two arms consisting of identical silicon-on-insulator (SOI) optical waveguides is presented. The operability of the presented interferometer is simulated both for the continue wave (cw) and pulsed probe signals. It is shown that at the output port of the MZI, the switching window of the probe signal is strongly dependent on the energy and duration of the ultrafast control pulse and the SOI waveguide length. In addition, the initial delay time between both two optical waves will significantly affect the optical switching window when a pulsed probe signal wave is used. (integrated optics)

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. All-optical manipulation and probing of the d–f exchange interaction in EuTe

    PubMed Central

    Subkhangulov, R. R.; Henriques, A. B.; Rappl, P. H. O.; Abramof, E.; Rasing, Th.; Kimel, A. V.

    2014-01-01

    We demonstrate that the ultrafast fast dynamics of the d–f exchange interaction, between conduction band electrons and lattice spins in EuTe, can be accessed using an all-optical technique. Our results reveal, in full detail, the time evolution of the d–f exchange interaction induced by a femtosecond laser pulse. Specifically, by monitoring the time resolved dynamics of the reflectivity changes and Kerr rotation of a weak light pulse reflected from the surface of the sample, it is shown that an intense femtosecond light pulse with photon energies higher than that of the bandgap, triggers spin waves in EuTe. The laser-induced spin waves modulate the d–f exchange interaction, and cause the bandgap to oscillate with an amplitude reaching 1 meV, at frequencies up to tens of GHz. The ability to control and monitor the dynamics of the exchange energy with our all-optical technique opens up new opportunities for the manipulation of magnetism at ultrafast time-scales. PMID:24658449

  17. A novel all-optical label processing for OPS networks based on multiple OOC sequences from multiple-groups OOC

    NASA Astrophysics Data System (ADS)

    Qiu, Kun; Zhang, Chongfu; Ling, Yun; Wang, Yibo

    2007-11-01

    This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS) for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is performed. These analysis and results show that the proposed scheme can overcome the lack of available optical orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short code length, and indicate that the MOOCS-OPS scheme is feasible.

  18. External cavity based single mode Fabry-Pérot laser diode and its application towards all-optical digital circuits

    NASA Astrophysics Data System (ADS)

    Nakarmi, Bikash; Zhang, Xuping; Won, Yong Hyub

    2012-11-01

    We have proposed a novel approach of realizing all-optical logic gates and combinational circuit using external cavity based single mode Fabry-Pérot laser diodes (SMFP-LDs). Different techniques and critical parameters for injection locking the any one of the modes of SMFP-LDs are discussed. Taking consideration of wavelength detuning and input injected power, we have proposed and demonstrated multi-input injection locking, supporting beam injection locking with the conventional injection locking which are used for demonstrating different logic gates (NAND, AND, XNOR, XOR, NOT, NOR) and digital circuits (Half adder and Comparator). Since we have used SMFP-LDs, there is no requirement of additional probe beam and associated components as required by other optical technologies making the realization simple in configuration, cost effective and power efficient. Clear output waveforms, eye diagrams, risingfalling times and BER are presented to verify the proposed method. All-optical logic units and digital circuit are demonstrated at the data rate of 10 Gbps with the waveform of NRZ signal waveform and measured eye diagram and BER of the PRBS of 231-1 signal. The maximum power penalty among all demonstrated units is below 1.4 dB at the BER of 10-9.

  19. All-optical switching in bacteriorhodopsin based on M state dynamics and its application to photonic logic gates

    NASA Astrophysics Data System (ADS)

    Singh, Chandra Pal; Roy, Sukhdev

    2003-03-01

    All-optical switching has been theoretically analyzed in bacteriorhodopsin (bR) based on nonlinear intensity induced excited state absorption of the M state. The transmission of a cw probe laser beam at 410 nm corresponding to the peak absorption of M state through a bR film is switched by a pulsed pump laser beam at 570 nm that corresponds to the maximum initial B state absorption. The switching characteristics have been numerically simulated using the rate equation approach considering all the six intermediate states (B, K, L, M, N and O) in the bR photocycle. The switching characteristics are shown to be sensitive to various parameters such as the pump pulse width, pump intensity, life time of the M state, thickness of the film and absorption cross-section of the B-state at probe wavelength ( σBp). It has been shown that the probe laser beam can be completely switched off (100% modulation) by the pump laser beam at relatively low pump powers, for σBp=0. The switching characteristics have also been used to theoretically design all-optical NOT, OR, AND and the universal NOR and NAND logic gates with two pulsed pump laser beams using the six state model.

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

    PubMed

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

    2016-01-01

    The nanoscale chip-integrated all-optical logic parity checker is an essential core component for optical computing systems and ultrahigh-speed ultrawide-band information processing chips. Unfortunately, little experimental progress has been made in development of these devices to date because of material bottleneck limitations and a lack of effective realization mechanisms. Here, we report a simple and efficient strategy for direct realization of nanoscale chip-integrated all-optical logic parity checkers in integrated plasmonic circuits in the optical communication range. The proposed parity checker consists of two-level cascaded exclusive-OR (XOR) logic gates that are realized based on the linear interference of surface plasmon polaritons propagating in the plasmonic waveguides. The parity of the number of logic 1s in the incident four-bit logic signals is determined, and the output signal is given the logic state 0 for even parity (and 1 for odd parity). Compared with previous reports, the overall device feature size is reduced by more than two orders of magnitude, while ultralow energy consumption is maintained. This work raises the possibility of realization of large-scale integrated information processing chips based on integrated plasmonic circuits, and also provides a way to overcome the intrinsic limitations of serious surface plasmon polariton losses for on-chip integration applications. PMID:27073154