We demonstrate what we believe to be the first real-time impairment-cancellation system for group-velocity dispersion (GVD) and differential group delay (DGD) for a 640 Gb/s single-channel signal. Simultaneous compensation of two independent parameters is demonstrated by feedback control of separate GVD and DGD compensators using an impairment monitor based on an integrated all-optical radio-frequency (RF) spectrum analyzer. We show that low-bandwidth measurement of only a single tone in the RF spectrum is sufficient for automatic compensation for multiple degrees of freedom using a multivariate optimization scheme.
We propose and demonstrate the first photonic-chip based all-optical error detection. The scheme could provide a favourable solution for communication systems with ultra-low latency requirements. We present results for 40 Gb/s BPSK signals.
Reservoir Computing is a novel computing paradigm which uses a nonlinear recurrent dynamical system to carry out information processing. Here we will present an optoelectronic and an all-optical implementation of Reservoir Computers based on an architecture with a single nonlinear node and a delay loop. Moreover we will present an optical analogue readout which makes our reservoir computer a potential standalone solution after training. Our works show that, within the Reservoir Computing paradigm, all-optical computing with state-of-the-art performance is possible as a self-contained solution.
Summary form only given. Four-wave mixing and other parametric nonlinear processes have been the subject of much research over the last decades. In particular phase sensitive amplification in optical parametric amplifiers holds great potential for signal processing in optical telecommunications, e.g. for the regeneration of phase encoded signals [1] or as potentially broadband, noiseless amplifiers [2].While there are some demonstrations of phase-sensitive amplification and regeneration in chip-like architectures based on the second-order χ(2) nonlinearity [3] in periodically-poled Lithium Niobate waveguides, most demonstrations thus far have been using highly nonlinear fibre with the associated limitations on bandwidth and integrability. In particular there has not been a demonstration of phase-sensitive amplification inside a χ(3)-based integrated platform such as Silicon or highly nonlinear glasses. In this submission we demonstrate for the first time phase-sensitive amplification inside a χ(3) photonic chip using a highly nonlinear chalcogenide waveguide. Our demonstration is based on an elegant spectral control technique that slices the pump and signal waves from the same broadband spectrum of a mode-locked laser, thus significantly simplifying the challenges of ensuring synchronization of the waves while enabling accurate control of the relative phase of the interacting waves.The experimental setup is depicted in Fig. 1(a). A mode-locked laser (repetition rate 38.6 MHz, 300 fs pulse duration, 160 W peak power), is spectrally sliced using a spectral pulse shaper (SPS 1), to yield two pump waves at 1550.1 nm and 1564.5 nm (spectral width ~70 GHz) and a degenerate signal/idler at 1557.7 nm (width ~130 GHz). After amplification all waves are polarisation aligned and coupled to the TM-mode of the chalcogenide waveguide. A second SPS provides filtering of excess noise and the required phase control. The output of the waveguide is measured with an optical spectrum analyser (OSA). The phase-sensitive gain is characterised by changing the relative phase of the interacting waves using SPS 2 and measuring the power of the signal relative to the unamplified signal. The approximate on-chip peak powers were 4.8 W and 2.5 W for the two pumps and 4 mW for the signal. Figures 1(b) and (c) depict output spectra and the on-chip signal gain as a function of relative phase. We can see a clear periodic dependence of the gain on the relative phase. The period of the variation is π and the ratio of maximum gain to minimum gain, i.e the main performance indicator often denoted the phase-sensitive gain, was 9.9 dB. The experimental results agree well with numerical simulations of the underlying nonlinear Schrodinger equation using a split-step Fourier method. In conclusion we have for the first time shown phase-sensitive amplification on a χ(3) photonic chip. We achieved a phase-sensitive gain of 9.9 dB which is comparable to previous demonstrations, and is sufficient to perform other processing functions such as regeneration of phase-encoded communication signals. Prospects for extending our experiment to continuous or quasicontinuous wave operation are promising and currently ongoing.
We present the first automatic and simultaneous compensation of combined higher-order dispersion and GVD fluctuations of a 1.28 Tbaud signal using a photonic-chip based RF-spectrum analyser and a spectral pulse-shaper.
We report phase-sensitive amplification of light using χ((3)) parametric processes in a chalcogenide ridge waveguide. By spectrally slicing pump, signal and idler waves from a single pulsed source, we are able to observe 9.9 dB of on-chip phase-sensitive extinction with a signal-degenerate dual pump four-wave mixing architecture in good agreement with numerical simulations.
We introduce an all-optical arithmetic unit operating a weighted addition and subtraction between multiple phase-and-amplitude coded signals. The scheme corresponds to calculating the field dot-product of frequency channels with a static vector of coefficients. The system is reconfigurable and format transparent. It is based on Fourier-domain processing and multiple simultaneous four-wave mixing processes inside a single nonlinear element. We demonstrate the device with up to three channels at 40 Gb/s and evaluate its efficiency by measuring the bit-error-rate of a distortion compensation operation between two signals.
Reservoir computing is a new, powerful and flexible machine learning technique that is easily implemented in hardware. Recently, by using a time-multiplexed architecture, hardware reservoir computers have reached performance comparable to digital implementations. Operating speeds allowing for real time information operation have been reached using optoelectronic systems. At present the main performance bottleneck is the readout layer which uses slow, digital postprocessing. We have designed an analog readout suitable for time-multiplexed optoelectronic reservoir computers, capable of working in real time. The readout has been built and tested experimentally on a standard benchmark task. Its performance is better than non-reservoir methods, with ample room for further improvement. The present work thereby overcomes one of the major limitations for the future development of hardware reservoir computers.
We introduce an all-optical, format transparent hash code generator and a hash comparator for data packets verification with low latency at high baudrate. The device is reconfigurable and able to generate hash codes based on arbitrary functions and perform the comparison directly in the optical domain. Hash codes are calculated with custom interferometric circuits implemented with a Fourier domain optical processor. A novel nonlinear scheme featuring multiple four-wave mixing processes in a single waveguide is implemented for simultaneous phase and amplitude comparison of the hash codes before and after transmission. We demonstrate the technique with single polarisation BPSK and QPSK signals up to a data rate of 80 Gb/s.
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