Gain flattened and C/L band amplified spontaneous emission noise re-injected L-band EDFA

Explosive increase in internet services put peer pressure on conventional band grid (1530–1570 nm) and therefore L-band wide wavelength grid is required to cater the ever-increasing demands. In this work, accentuation is given to enhance the gain flattening of ultradense (25 GHz) L-band WDM system using single stage EDFA amplifier when ultralow power is launched from 16 and 32 channels. High gain and gain flattening is achieved by incorporating three fiber Bragg gratings (FBGs) for amplified spontaneous noise reinjection. Maximum Amplified spontaneous emission (ASE) is emerged at 1565 nm for the 1575.69–1579 nm input wavelengths (16 channels) and 1572.58–1579 nm (32 channels) at −55 dBm ultra low carrier powers. To optimize different parameters of L-band EDFA, different physical parameters such as core radius, EDF link lengths, and launched powers are varied, and results are analyzed in terms of lateness. Maximum gain is found out to be 34.12 dB at optimal physical parameters of the EDF with gain flatness of ±0.45 dB in case of 16 channels and ±1.41 in case of 32 channels.

Harnessing Optoelectronic Noises in a Hybrid Photonic Generative Adversarial Network (GAN)

Integrated programmable optoelectronics is emerging as a promising platform of neural network accelerator, which affords efficient in-memory computing and high bandwidth interconnectivity. The analog nature of optical computing and the inherent optoelectronic noises, however, make the systems error-prone in practical implementations such as classification by discriminative neural networks. It is thus imperative to devise strategies to mitigate and, if possible, harness optical and electrical noises in optoelectronic computing systems. Here, we demonstrate a prototypical hybrid photonic generative adversarial network (GAN) that generates handwritten numbers using an optoelectronic core consisting of an array of programable phase-change optical memory cells. We harness optoelectronic noises in the hybrid photonic GAN by realizing an optoelectronic random number generator derived from the amplified spontaneous emission noise, applying noise-aware training by injecting additional noise to the network, and implementing the trained network with resilience to hardware non-idealities. Surprisingly, the hybrid photonic GAN with hardware noises and inaccuracies can generate images of even higher quality than the noiseless software baseline. Our results suggest the resilience and potential of more complex hybrid generative networks based on large-scale, non-ideal optoelectronic hardware. The demonstrated GAN architecture and the proposed noise-aware training approach are generic and thus applicable to various types of optoelectronic neuromorphic computing hardware.

Performance analysis and modeling: atmospheric turbulence and crosstalk of WDM-FSO network

A wavelength division multiplexing (WDM) access network using high-speed free-space optical (FSO) communication for the distribution link is proposed. This Paper investigates terrestrial atmospheric of WDM-FSO communication systems operating under the influence of turbulence-induced scintillation, beam spreading, optical interchannel crosstalk, amplified spontaneous emission noise and pointing errors.On-off keying-non–return-to-zero and digital pulse position modulation are the modulation schemes used for the calculations.

Performance analysis and modeling: atmospheric turbulence and crosstalk of WDM-FSO network

A wavelength division multiplexing (WDM) access network using high-speed free-space optical (FSO) communication for the distribution link is proposed. This Paper investigates terrestrial atmospheric of WDM-FSO communication systems operating under the influence of turbulence-induced scintillation, beam spreading, optical interchannel crosstalk, amplified spontaneous emission noise and pointing errors. On-off keying-non–return-to-zero and digital pulse position modulation are the modulation schemes used for the calculations.

Polarization rotation-based all-optical AND gate using single semiconductor optical amplifier and implementation of a majority gate

Semiconductor optical amplifier-based polarization rotation is utilized in designing all-optical AND gate at 100 Gbps. The AND gate shows high extinction ratio (ER ∼ 15 dB), contrast ratio (CR ∼ 18 dB) and quality factor (Q-factor ∼ 16 dB). The effect of the amplified spontaneous emission noise on the performances is also investigated. The AND gate has relative eye opening (REO) varying from 93.52 to 97.1% for 10–30 dB unsaturated gain. Using the AND gate a majority voting gate is designed and analyzed and has Q ∼ 11.7 dB with REO ∼ 91%.

Optimization of Probabilistic Shaping for Nonlinear Fiber Channels with Non-Gaussian Noise

Probabilistic constellation shaping is investigated in the context of nonlinear fiber optic communication channels. Based on a general framework, different link types are considered—1. dispersion-managed channels, 2. unrepeatered transmission channels and 3. ideal distributed Raman amplified channels. These channels exhibit nonlinear effects to a degree that conventional probabilistic constellation shaping strategies for the additive white Gaussian (AWGN) noise channel are suboptimal. A channel-agnostic optimization strategy is used to optimize the constellation probability mass functions (PMFs) for the channels in use. Optimized PMFs are obtained, which balance the effects of additive amplified spontaneous emission noise and nonlinear interference. The obtained PMFs cannot be modeled by the conventional Maxwell-Boltzmann PMFs and outperform optimal choices of these in all the investigated channels. Suboptimal choices of constellation shapes are associated with increased nonlinear effects in the form of non-Gaussian noise. For dispersion-managed channels, a reach gain in 2 spans is seen and across the three channel types, gains of >0.1 bits/symbol over unshaped quadrature-amplitude modulation (QAM) are seen using channel-optimized probablistic shaping.

Design and performance analysis of all optical 4-bit parity generator and checker using dual-control dual SOA terahertz optical asymmetric demultiplexer (DCDS-TOAD)

Tera hertz optical asymmetric demultiplexer (TOAD) using two semiconductor optical amplifiers and two control signals has been used to design an all optical parity checker and generator. The same circuit can generate and check both even and odd parity using a control input. The numerical simulation using Matlab 2007b is done for performance analysis of the proposed device in terms of output bit pattern, amplified spontaneous emission (ASE) noise, extinction ratio, contrast ratio, pseudo eye diagram, relative eye opening (98.9% for 20 dB gain and 96.21% for 10 dB gain) and their variation with input control pulse energy, amplified spontaneous emission noise factor for different unsaturated gain. The simulated value of E.R. = 81.39 dB, C.R. = 83.15 dB, REOP = 98.9% and Q value = 86.16 dB are found for this proposal.

Non-Adaptive Decision Thresholds for Gain Saturated FSO Links Limited by Weak to Strong Turbulence and Pointing Errors

In free space optical (FSO) communication systems limited by atmospheric turbulence, the use of non-adaptive decision thresholds to determine the transmitted bits results in bit error rate (BER) floors at high BER values in all turbulence regimes. Practically implementing an adaptive decision threshold that can properly track the fluctuations due to atmospheric turbulence is challenging, therefore, devising ways of optimising the non-adaptive decision threshold used by FSO designers is necessary. In this paper, the investigation of gain saturated pre-amplified FSO communication systems using non-adaptive decision thresholds in the presence of atmospheric turbulence, pointing errors (PEs), geometric spread (GS) and amplified spontaneous emission noise is carried out by applying analytical methods and Monte Carlo (MC) simulation techniques. System performance is carried out for various turbulence regimes, normalised beam widths, normalised PE standard deviations and small signal gains using fixed gain and gain saturated optical amplifiers (OAs). Results obtained show that in the presence of atmospheric turbulence, PE and GS, optimal BER performances are obtained with OA input powers higher than the internal saturation power of the OA. Also, by using high gain OAs and varying the decision threshold level, acceptable BER performances can be obtained in strong turbulence regimes with a non-adaptive decision threshold.

Simultaneous monitoring of chromatic dispersion and optical signal to noise ratio in optical links using convolutional neural network and asynchronous delay-tap sampling

The article presents a method for image analysis using asynchronous delay-tap sampling (ADTS) technique and convolutional neural networks (CNNs), allowing simultaneous monitoring of many phenomena occurring in the physical layer of the optical network. The ADTS method makes it possible to visualize the course of the optical signal in the form of characteristics (so-called phase portraits), which change their shape under the influence of phenomena (including chromatic dispersion, amplified spontaneous emission noise and other). Using the VPIphotonics software, a simulation model of the ADTS technique was built. After the simulation tests, 10 000 images were obtained, which after proper preparation were subjected to further analysis using CNN algorithms. The main goal of the study was to train a CNN to recognize the selected impairment (distortion); then to test its accuracy and estimate the impairment for the selected set of test images. The input data consisted of processed binary images in the form of two-dimensional matrices, with the position of the pixel. This article focuses on the analysis of images containing simultaneously the phenomena of chromatic dispersion and optical signal to noise ratio.