- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Optical Transparent Antenna Array Integrated with Solar Cell
摘要： We present the experimental implementation of an all-optical ROADM scheme for routing of an individual subchannel within an all-optical OFDM superchannel. The different functions required of optical node were demonstrated using interferometric technique with the extraction, drop, and addition of individual subchannel in a ten subchannels optically aggregated signal. The scheme we reported enables a fully ?exible node compatible with future terabit per second superchannel transmission.
关键词： interferometer,optical communication,all-optical OFDM,All-optical node,?exible optical networks,subcarrier multiplexing
更新于2025-09-19 17:13:59
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Capacity analysis of free space optical communication system under atmospheric turbulence
摘要： In this paper, the analytical channel capacity of the free space optical (FSO) system under weak, moderate and strong turbulence is derived. The FSO channel statistics follows the log-normal distribution under weak turbulence and follows the Gamma–Gamma distribution under moderate and strong turbulence. The three generally used adaptive transmission schemes in FSO communication system are as follows (1) optimal simultaneous power and rate adaptation, (2) optimal rate adaptation with constant transmit power, and (3) truncated channel inversion with a fixed rate. The closed-form approximations for the average ergodic channel capacity for these adaptive transmission schemes under different atmospheric turbulence without any pointing error are derived. Simulation results depict the excellent agreement of the proposed analytical models with the Monte Carlo simulation.
关键词： Channel capacity,Free space optical communication,Signal to noise ratio,Adaptive transmission,Atmospheric turbulence
更新于2025-09-19 17:13:59
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Introducing Enumerative Sphere Shaping for Optical Communication Systems with Short Blocklengths
摘要： Probabilistic shaping based on constant composition distribution matching (CCDM) has received considerable attention as a way to increase the capacity of fiber optical communication systems. CCDM suffers from significant rate loss at short blocklengths and requires long blocklengths to achieve high shaping gain, which makes its implementation very challenging. In this paper, we propose to use enumerative sphere shaping (ESS) and investigate its performance for the nonlinear fiber optical channel. ESS has lower rate loss than CCDM at the same shaping rate, which makes it a suitable candidate to be implemented in real-time high-speed optical systems. In this paper, we first show that finite blocklength ESS and CCDM exhibit higher effective signal-to-noise ratio than their infinite blocklength counterparts. These results show that for the nonlinear fiber optical channel, large blocklengths should be avoided. We then show that for a 400 Gb/s dual-polarization 64-QAM WDM transmission system, ESS with short blocklengths outperforms both uniform signaling and CCDM. Gains in terms of both bit-metric decoding rate and bit-error rate are presented. ESS with a blocklength of 200 is shown to provide an extension reach of about 200 km in comparison with CCDM with the same blocklength. The obtained reach increase of ESS with a blocklength of 200 over uniform signaling is approximately 450 km (approximately 19%).
关键词： optical communication systems,enumerative sphere shaping,probabilistic shaping,fiber nonlinearity,Constant composition distribution matching
更新于2025-09-19 17:13:59
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Non-Kolmogorov atmospheric turbulence and orbital angular momentum of entangled states for optical communication
摘要： We extend the theory of detection probabilities of single-photon communication in turbulent atmosphere to the entangled case and derive analytical expressions for detection probabilities. We show that the rotational ?eld correlation in the entangled case cannot be expressed as a straightforward extension from the disentangled case. By considering the orbital angular momentum (OAM) entangled Laguerre-Gaussian (LG) beams for illustration, we explore the e?ect of non-Kolmogorov atmospheric turbulence on the probabilities of both the biphoton detection and the single-photon detection. The entanglement of OAM LG beams contributes positively to the faithful detection probability. The change of maximal crosstalk probability in the detection process is also explored, which displays the non-linear dependence on the crosstalk quantum number.
关键词： Atmospheric turbulence,Orbital angular momentum,Entanglement,Optical communication
更新于2025-09-19 17:13:59
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Using the Belinfante momentum to retrieve the polarization state of light inside waveguides
摘要： current day high speed optical communication systems employ photonic circuits using platforms such as silicon photonics. In these systems, the polarization state of light drifts due to effects such as polarization mode dispersion and nonlinear phenomena generated by photonic circuit building blocks. As the complexity, the number, and the variety of these building blocks grows, the demand increases for an in-situ polarization determination strategy. Here, we show that the transfer of the Belinfante momentum to particles in the evanescent field of waveguides depends in a non-trivial way on the polarization state of light within that waveguide. Surprisingly, we find that the maxima and minima of the lateral force are not produced with circularly polarized light, corresponding to the north and south poles of the Poincaré sphere. Instead, the maxima are shifted along the great circle of the sphere due to the phase differences between the scattered TE and TM components of light. This effect allows for an unambiguous reconstruction of the local polarization state of light inside a waveguide. Importantly, this technique depends on interaction with only the evanescent tails of the fields, allowing for a minimally invasive method to probe the polarization within a photonic chip.
关键词： waveguides,Poincaré sphere,Belinfante momentum,evanescent field,optical communication,photonic chip,TE and TM components,silicon photonics,polarization state
更新于2025-09-19 17:13:59
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Design of a MEMS-Mirror-based Laser Pointing Control System of Optical Transponder for Micro-satellites
摘要： Optical communication technologies are regarded as an important breakthrough for future satellite communications. Tohoku University has been developing Adjustable beam angle Small Optical TrAnsponder (ASOTA) for micro-satellites. The design concept of ASOTA is miniaturization and low power consumption. It is necessary for space optical communication to direct the laser to the ground station with a high precision. This research describes the development of a MEMS-Mirror-based Fine Pointing Mechanism (FPM). The MEMS mirror is suitable for micro-satellites because it is smaller and consumes less power than 2-axis gimbal mechanisms. FPM is a feedback control system consisting of a MEMS mirror and a Quadrant Detector. The characteristics and mathematical model of each device are described. Then numerical simulation and ground evaluation results of FPM with a simple optical system are summarized.
关键词： Optical Communication,Laser Tracking,MEMS Mirror,Closed Loop Control,Micro-satellite
更新于2025-09-19 17:13:59
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Phase Alignment With Minimum Complexity for Equal Gain Combining in Multi-Aperture Free-Space Digital Coherent Optical Communication Receivers
摘要： Digital coherent combining (DCC) technique can increase the free space optical signal collection area by combining the signals received by an array of small apertures in a coherent manner. To realize DCC the different versions of signals must be aligned in phase by the digital phase alignment algorithm (PAA). Low computation complexity is imperative for the PAA because the main obstacle to implement the PAA and DCC in a real-time manner is the availability of digital signal processing (DSP) circuits offering very high gate density and processing speed. In this paper we investigate the relationship between the computation complexity, optical phase offset estimation error and the combining loss for the equal gain combining technique. Analytical expressions are deduced allowing easy minimization of the computation complexity at an arbitrary input OSNR and acceptable combining loss. Extensive numerical simulations are carried out to validate the analytical expressions.
关键词： Multi-aperture free-space optical communication receivers,combining loss,minimum complexity,phase estimation error,phase alignment,digital coherent combining
更新于2025-09-19 17:13:59
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Toward Long-Distance Underwater Wireless Optical Communication Based on A High-Sensitivity Single Photon Avalanche Diode
摘要： In this study, we built a single photon avalanche diode (SPAD) receiver based underwater wireless optical communication (UWOC) system. The bit error rate (BER) and signal-to-noise ratio (SNR) performance of UWOC with different distances and data transmission rates were obtained. Based on the water attenuation coefficient of 0.12 m-1, a series of neutral density (ND) filters were exploited to attenuate the light output power from the blue laser diode (LD) to simulate the long distance UWOC. The maximum estimated distances of 144 m and 117 m with corresponding BERs of 1.89 × 10-3 and 5.31 × 10-4 at data transmission rates of 500 bps and 2 Mbps were acquired in UWOC system using on-off keying (OOK) modulation scheme, respectively. Furthermore, we compared the differences between free-space and underwater channels, and a divergence angle of ~1.02 mrad was measured experimentally at a distance of 50 m in the free space. The long UWOC distances obtained in this study partly benefit from high sensitivity SPAD, the small laser divergence angle and low light attenuation. This study provides an approach to achieve long distance UWOC using SPAD.
关键词： laser,on-off keying,single photon avalanche diode (SPAD),Underwater wireless optical communication (UWOC)
更新于2025-09-19 17:13:59
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[IEEE 2019 6th NAFOSTED Conference on Information and Computer Science (NICS) - Hanoi, Vietnam (2019.12.12-2019.12.13)] 2019 6th NAFOSTED Conference on Information and Computer Science (NICS) - Alignment Error Mitigation Techniques for Airborne Free-Space Optical Communication Systems
摘要： We present our recent research activities on the mitigation of impacts of angle-of-arrival fluctuations and alignment errors on the performance of free-space optical communication systems. We report on the adaptive beam control technique and wide field-of-view receiver based on multi-core fiber for the transmitter and receiver, respectively.
关键词： pointing errors,Free-space optical communication (FSOC) systems,angle-of-arrival (AoA) fluctuations
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Clock Recovery Based on Adaptive Phase Error Detection for Coherent Optical Transmission Systems
摘要： Traditional clock recovery techniques rely on Gardner for phase error detection to recover the original signal. An adaptive phase splitting detection technique is proposed by joint channel equalization in this paper. The loop judges the current error by the error of the previous moment, reduces the phase error jitter, and improves the stability of the system. In addition, the algorithm works well for the same phase of adjacent symbols through phase splitting techniques. In fiber channel, this scheme is more suitable for the case of small roll-off factor (ROF). Simulation results show that the algorithm is suitable for signals modulated by MQAM. The algorithm performs very well even when the ROF approaches 0.
关键词： Adaptive phase error detection,Phase splitting timing recovery,Channel equalization,Coherent optical communication
更新于2025-09-19 17:13:59