We experimentally demonstrate an optoacoustic recurrent operator (OREO) based on stimulated Brillouin scattering, which enables recurrent functionalities for photonic machine learning and neural network applications. OREO employs sound waves to catch and process the context defined by a sequence of optical pulses. It controls the coherent recurrent operation completely optically on pulse-by-pulse level without the need of an artificial reservoir. We demonstrate OREO's capability to compute correlations in pulse trains. Then, we use the pulse-by-pulse control of OREO to implement recurrent dropout. Furthermore, we use OREO to recognize patterns of optical pulse trains, in which we can distinguish up-to 27 different patterns. Eventually, OREO can be used as key component of a bi-directional perceptron, bring a new class of photonic neural networks within reach.
|