- 标题
- 摘要
- 关键词
- 实验方案
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5-Channel Polymer/Silica Hybrid Arrayed Waveguide Grating
摘要： A 5-channel polymer/silica hybrid arrayed waveguide grating (AWG), fabricated through a simple and low-cost microfabrication process is proposed, which covers the entire O-band (1260–1360 nm) of the optical communication wavelength system. According to the simulation results, the insertion loss is lower than 4.7 dB and the crosstalk within 3-dB bandwidth is lower than ~?28 dB. The actual fiber–fiber insertion loss is lower than 14.0 dB, and the crosstalk of the 5 channels is less than ?13.0 dB. The demonstrated AWG is ideally suitable for optical communications, but also has potential in the multi-channel sensors.
关键词： integrated optics,polymer optical waveguides,planar lightwave circuit,optical communication systems
更新于2025-09-23 15:19:57
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Transmission characteristics of 24.5??Gb/s atmospheric laser communication based on optical frequency comb
摘要： Through cascading Mach–Zehnder intensity modulator (MZIM) and phase modulator (PM), an optical frequency comb (OFC) with 7 flat comb teeth is produced. The frequency interval of the OFC is 25 GHz and the flatness is less than 1.5 dB. The 7 channels of the OFC are used as the carrier source of the one-to-many free-space optical (FSO) communication system, and the atmospheric turbulence simulation pool is used to simulate the turbulence intensity in the real atmosphere to verify its feasibility for FSO communication. In the experiment, the bit error rate (BER) and eye diagram are measured under the back-to-back (BTB) conditions, and the temperature difference of atmospheric turbulence simulation pool are 80 ?C, 150 ?C and 220 ?C. Each channel of the system can stably transmit the on–off keying (OOK) signal of 3.5 Gb/s, and the 7 channels can stably transmit the OOK signal of 24.5 Gb/s. Thereby, the OFC can be used in place of multiple lasers or laser arrays as a carrier source for a one-to-many FSO communication system.
关键词： Wavelength division multiplexing,Optical frequency comb,Atmospheric turbulence,Free-space optical communication
更新于2025-09-23 15:19:57
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Special Issue on Optical Communications and Networking: Prospects in Industrial Applications
摘要： In the past two decades, Internet traffic has increased by over 10,000 times by taking advantage of both efficient information processing technology in the electronic domain and efficient transmission technology in the optical domain, which are the foundation of today’s Internet infrastructure [1,2]. The advancement of electronics processing circuits has followed Moore’s law, and perhaps will continue this exponential growth for years to come. This may make the electrical systems significantly outpace the advancement of optical systems in information and communications technologies. To support the ever-growing Internet traffic, optical communication systems face a great challenge in transporting information processed by electronic systems for sustained exponential growth. The industry has explored multiple degrees of freedom of the photon (time, wavelength, amplitude, phase, polarization, and space) to significantly reduce the cost/bit for data transmission by increasing the capacity/fiber through multiplexing and reducing the size and power through integration.
关键词： optical communication systems,networking,optical communications,industrial applications,Internet traffic
更新于2025-09-23 15:19:57
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Design and Analysis of Variation in Chlorophyll and Depth for Open Ocean Underwater Optical Communication
摘要： The underwate communication is of great interest of research for many researchers because of increased dealings of human beings with world exists underwater. Underwater Commu- cation Technology (UCT) is becoming an important part of communication technologies. These include communication between divers, ships, and network system for autonomous underwater vehicles. However, optical communication with underwater exchange of infor- mation is challenged with many issues. In this paper, the attenuation for optical transmis- sion is obervsed for optical waves that are absorbing inside water, in result, suspending par- ticles and planktons produces optical scattering indirectly. In connection, underwater needs to rectify high attenuation regions for analysing ocean composition affects in Deep Ocean. This produces chlorophyll profiles that identify the attenuation in underwater communica- tion.with high attenuation. In past studies, the constant attenuation is observed irrespective of depth of occean. Furthemore, the paper address, optical attenuation for underwater com- munication via depth dependent. The system is tested for 400–700 nm and 0–250 m depth for chlorophyll concentration profile (S1–S9). The system is demonstrated via GUI devel- oped in Matlab that shows the optical attenuation at different depths underwater and along with that regions with deep chlorophyll maximum (DCM) are also shown.
关键词： Deep ocean depth,Optical attenuation,Deep chlorophyll maximum (DCM),Under water optical communication systems
更新于2025-09-23 15:19:57
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Parallelized and adaptive square-root unscented Kalman filter for carrier recovery in satellite-to-ground coherent optical communications
摘要： An adaptive square-root unscented Kalman filter with a parallelized architecture for carrier recovery is proposed in QPSK based satellite-to-ground coherent optical communication systems. A new observation model is raised in the proposed scheme to make the state estimation more accurate. The process noise covariance (Q) and the measurement noise covariance (R) are adaptively estimated to make them consistent with their theoretical covariance. For verification of the feasibility of the proposed scheme, corresponding simulations of carrier recovery in satellite-to-ground laser links are carried out and compared with the scheme that is based on linear Kalman filter (LKF). The simulation results demonstrate that, compared with parallelized LKF, the proposed scheme has a wider range of block size and laser linewidth options, and it can relax the required transmit power by up to 0.5-3 dB under different zenith angle at the same BER. Moreover, the proposed scheme can achieve high estimation accuracy and fast tracking capability simultaneously in the case of dynamic frequency offset with better tolerance against the initial errors in Q and R.
关键词： Atmospheric propagation,Adaptive Kalman filter,Free space optical communication,Coherent communications,Carrier recovery
更新于2025-09-23 15:19:57
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Asymptotic Performance of Generalized Transmit Laser Selection Over Lognormal Turbulence Channels
摘要： In free space optical communication systems, transmit laser selection (TLS) has been proposed as an efficient fading-mitigation technique over turbulence channels. In TLS, the transmitter is equipped with a number of laser sources and the best laser source is selected for transmission. In practice, feedback error or outdated selection due to temporal changes in the channel may result in selecting another source rather than the best one. In this paper, we consider a FSOC system with generalized TLS (GTLS) where the nth best laser is selected among the available N lasers. Under the assumption of lognormal turbulence channels in addition to pointing errors, we derive a closed-form expression for asymptotic bit error rate. We use our derived closed-form expression to determine the diversity gains. We finally present simulation results to corroborate our analytical findings.
关键词： Free space optical communication,diversity order,lognormal fading,generalized transmit laser selection
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Precursor reaction method with high Ga Cu(In,Ga)(S,Se) <sub/>2</sub> to achieve increased open-circuit voltage
摘要： Direct detection transceivers offer advantages, including low cost and complexity, in short- and medium-haul links. We carried out studies seeking to identify the signal formats which offer the highest information spectral densities and maximum transmission distances for direct detection links. The performance of two spectrally efficient optical signal formats, single-sideband (SSB) Nyquist pulse-shaped subcarrier modulation (SCM) and SSB orthogonal frequency-division multiplexing (OFDM), are compared by means of simulations. The comparison is performed for a range of wavelength-division multiplexing (WDM) net information spectral densities up to 2.0 b/s/Hz by varying the signal bandwidth, modulation cardinality, and WDM channel spacing. The signal formats’ tolerance to signal–signal beating interference, resulting from square-law detection, is investigated, and the Nyquist-SCM format is found to suffer lower penalties from this nonlinearity at high information spectral densities. In 7 × 28 Gb/s WDM transmission at 2.0 b/s/Hz (with electronic pre-distortion and EDFA-only amplification), Nyquist-SCM signals can be transmitted over distances of up to 720 km of standard SMF in comparison to a maximum of 320 km with the OFDM signal format.
关键词： Digital signal processing,direct detection,wavelength division multiplexing,subcarrier modulation,electronic pre-distortion,optical communication,Nyquist pulse shaping,signal–signal beating interference,orthogonal frequency division multiplexing
更新于2025-09-23 15:19:57
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Functional-Link Neural Network for Nonlinear Equalizer in Coherent Optical Fiber Communications
摘要： We propose and experimentally demonstrate a simple nonlinear equalizer based on functional-link neural network (FLNN). The nonlinear stochastic mapping enables FLNN to serve as a nonlinear network, so we construct an FLNN with the signals from the two polarizations and the mapped features as input to combat the fiber nonlinearity in coherent optical transmission systems. The FLNN can use the Moore-Penrose generalized inverse or the ridge regression to solve the weights, which can speed up the training process, and avoid the iterative and time-consuming training process that exist universally in most of the deep neural networks. We also extend the FLNN to the multi-channel transmissions. All of the received signals from different channels are stretched as the input and then we use a joint FLNN to extract features and equalize the nonlinear distortions. We conduct simulations and experiments to verify the proposed scheme. In the simulation and experiment, we transmit a 128 Gb/s polarization division multiplexed 16-QAM (PDM-16-QAM) signal over 1000-km and 600-km standard single mode fiber (SSMF), respectively. Both the simulation and experimental results show that the FLNN has similar performance as deep neural network (DNN), which can improve the transmission performance in the nonlinear region. Moreover, the FLNN can avoid the gradient dissipation and local minimum problems in DNN, which simplify the training process. We also extend the proposed scheme in a five-channel (5 × 160 Gb/s) multiplexed transmission system. In simulation, we use joint FLNN and joint DNN to compensate the nonlinear distortions, respectively. We find that the BERs of the five channels can be below 7% HD-FEC with nonlinear equalizer.
关键词： enhancement node,functional-link neural network,Optical communication,deep neural network,fiber nonlinearity
更新于2025-09-23 15:19:57
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Performance studies of MIMO based DCO-OFDM in underwater wireless optical communication systems
摘要： The research in underwater communication system is focused towards wireless networks in view of recent developments in wireless technology and increasing need for deep sea data mining. The underwater wireless optical communication (UWOC) have more advantages for short-range wireless links due to very high bandwidth and data rate than acoustic communication. Although UWOC offers high capacity links at low latencies, they suffer from limited communication range due to various distinctive characteristics of underwater channel. A major degrading effect associated with the underwater channel is turbulence-induced fading. To mitigate this fading and to extend the viable communication range, spatial multipath diversity techniques can be adopted over UWOC links. The proposed work evaluates the performance of a multicarrier modulation scheme, i.e., MIMO based DC biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) for underwater wireless optical channel. The simulation of MIMO-DC biased optical OFDM technique employing spatial diversity in underwater optical communication is a novel approach towards the determination of an optimal modulation technique for underwater optical wireless channels. The performance is evaluated based on the various parameters such as Signal to Interference plus Noise Ratio (SINR), Throughput and Bit Error Rate (BER). A simple experiment is conducted to demonstrate the BER performance assessment for different link distance of 0.45 m and 1.5 m with different transmitter and receiver configurations (SIMO and MIMO) for both clear water and coastal water using MIMO DCO OFDM technique.
关键词： SNR,BER,MIMO,DCO-OFDM,QAM,Underwater wireless optical communication
更新于2025-09-23 15:19:57
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Performance of Free Space Optical Communication Base on Orbital Angular Momentum with Pointing Errors
摘要： Due to the misalignment of the receiver, the spiral spectrum appears to be extended when the Laguerre-Gaussian beam is applied to atmospheric laser communication. This paper investigates the spiral spectrum spread of the Laguerre-Gaussian beam in the case of receiver misalignment. The analytical expression of Laguerre-Gaussian spiral spectrum under the influence of alignment error is studied by mathematical derivation and simulation. The results show that the detection probability of the original orbital angular momentum (OAM) state varies with the lateral displacement distance and the inclination angle. The bit error rate and channel capacity of each channel were studied to verify the effects of misalignment in multiple OAM communication systems.
关键词： Orbital Angular Momentum,Laguerre-Gaussian beam,Pointing Errors,Free Space Optical Communication,Spiral Spectrum
更新于2025-09-23 15:19:57