Integrated photonic circuits offer a promising platform to implement matrix-vector multiplication in optical feedforward neural networks. The most common implementations rely on thermal phase shifters, which are inevitably susceptible to effects such as thermal and electrical crosstalk. Although deterministic, crosstalk-induced distortions have been challenging to accurately incorporate into physics-based analytical models. Additionally, analog hardware platforms suffer from fabrication deviations, that can have a significant impact on the computing performance, thus limiting scalability in implemented matrix size. In contrast, data-driven modeling techniques have shown to be promising approaches to modeling such circuits, yet they rely on black-box physics-agnostic modeling, require massive and unscalable amounts of training data, and cannot guarantee physically plausible results. Going beyond the data-driven black-box modeling techniques, but still taking advantage of the information captured by the data, we investigate the advantages of using physics-informed machine learning for photonic meshes. We analyze the ability of this approach to provide more accurate, less data-hungry, and physically plausible models for programmable photonic meshes. Moreover, we explore the potential to extract the knowledge from the trained model.
KEYWORDS: Machine learning, Control systems, Photonics systems, Design and modelling, Control systems design, Frequency combs, Telecommunications, Raman amplifiers, Optical circuits, Neural networks
Machine learning techniques are proving to be very useful for design of optical amplifiers, noise characterization of frequency combs, optimization of fiber-optic communications systems, inverse design of photonics components and quantum-noise limited signal detection. In this talk, we will review some of the successful applications of machine learning in photonics, and look into what is next in this emerging field. More specifically, we will look into how reinforcement learning can be used for the generation of programmable pulse shapes, which has a broad range of applications in classical and quantum engineering.
Machine learning (ML) is becoming a ubiquitous and powerful tool helping to address challenges in countless fields. Applications of ML addressing optics challenges have been extensively studied in recent years opening up new research directions. In particular, here, we review some of our current efforts and provide examples of successful applications of ML to the characterization of photonic devices, design, and modeling of optical subsystems, and complete end-to-end optical system optimization. ML and statistical tools can yield additional insight from measurement data, e.g. by targeted filtering of noise sources. They have also been shown to assist complex or inaccurate physics-based models through black and grey-box modeling of photonics components or subsystems. Such ML-aided models have enabled easier optimization and design (including inverse design) of optical systems.
KEYWORDS: Neural networks, Signal detection, Data centers, Signal processing, Receivers, Optoelectronics, Numerical analysis, Data communications, Computer architecture
The substantial increase in communication throughput driven by the ever-growing machine-to-machine communication within a data center and between data centers is straining the short-reach communication links. To satisfy such demand - while still complying with the strict requirements in terms of energy consumption and latency - several directions are being investigated with a strong focus on equalization techniques for intensity- modulation/direct-detection (IM/DD) transmission. In particular, the key challenge equalizers need to address is the inter-symbol interference introduced by the fiber dispersion when making use of the low-loss transmission window at 1550 nm. Standard digital equalizers such as feed-forward equalizers (FFEs) and decision-feedback equalizers (DFEs) can provide only limited compensation. Therefore more complex approaches either relying on maximum likelihood sequence estimation (MLSE) or using machine-learning tools, such as neural network (NN) based equalizers, are being investigated. Among the different NN architectures, the most promising approaches are based on NNs with memory such as time-delay feedforward NN (TD-FNN), recurrent NN (RNN), and reservoir computing (RC). In this work, we review our recent numerical results on comparing TD-FNN and RC equalizers, and benchmark their performance for 32-GBd on-off keying (OOK) transmission. A special focus will be dedicated to analyzing the memory properties of the reservoir and its impact on the full system performance. Experimental validation of the numerical findings is also provided together with reviewing our recent proposal for a new receiver architecture relying on hybrid optoelectronic processing. By spectrally slicing the received signal, independently detecting the slices and jointly processing them with an NN-based equalizer (wither TD-FNN or RC), significant extension reach is shown both numerically and experimentally.
KEYWORDS: Digital signal processing, Semiconductor lasers, Phase shift keying, Semiconductors, Receivers, Interference (communication), Signal to noise ratio, Frequency modulation, Transmitters, Optical communications
We discuss about digital signal processing approaches that can enable coherent links based on semiconductor lasers. A state-of-the art analysis on different carrier-phase recovery (CPR) techniques is presented. We show that these techniques are based on the assumption of lorentzian linewidth, which does not hold for monolithically integrated semiconductor lasers. We investigate the impact of such lineshape on both 3 and 20 dB linewidth and experimentally conduct a systematic study for 56-GBaud DP-QPSK and 28-GBaud DP-16QAM systems using a decision directed phase look loop algorithm. We show how carrier induced frequency noise has no impact on linewidth but a significant impact on system performance; which rises the question on whether 3-dB linewidth should be used as performance estimator for semiconductor lasers.
KEYWORDS: Signal to noise ratio, Fermium, Frequency modulation, Machine learning, Digital signal processing, Error analysis, Particle filters, Receivers, Laser beam characterization, Detection and tracking algorithms
The use of machine learning techniques to characterize lasers with low output power is reviewed. Optimized phase
tracking algorithms that can produce accurate noise spectra are discussed, and a method for inferring the amplitude noise
spectrum and rate equation model of the laser under test is presented.
We present a detailed experimental investigation of a hybrid optical-fiber wireless communication system operating at the 75 to 110 GHz (W-band) for meeting the emerging demands in short-range wireless applications. Measured W-band wireless channel properties such as channel loss, frequency response, phase noise, and capacity are reported. Our proposed system performs a sextuple frequency up-conversion after 20 km of fiber transmission, followed by a W-band wireless link. A 500 Mbit/s amplitude shift keying signal transmission is experimentally demonstrated for performance analysis purposes.
KEYWORDS: Orthogonal frequency division multiplexing, Polarization, Single mode fibers, Optical fibers, Radio over Fiber, Digital signal processing, Receivers, Computing systems, Multiplexing, Modulation
We propose and demonstrate a 2 × 2 multiple-input multiple-output (MIMO) wireless over fiber transmission
system. Seamless translation of two orthogonal frequency division multiplexing (OFDM) signals on dual optical
polarization states into wireless MIMO transmission at 795.5 Mbit/s net data rate is enabled by using digital
training-based channel estimation. A net spectral efficiency of 2.55 bit/s/Hz is achieved.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.