Genetic-algorithm-based deep neural networks for highly efficient photonic device design

While deep learning has demonstrated tremendous potential for photonic device design,it often demands a large amount of labeled data to train these deep neural network models.Preparing these data requires high-resolution numerical simulations or experimental measurements and cost significant,if not prohibitive,time and resources.In this work,we present a highly efficient inverse design method that combines deep neural networks with a genetic algorithm to optimize the geometry of photonic devices in the polar coordinate system.The method requires significantly less training data compared with previous inverse design methods.We implement this method to design several ultra-compact silicon photonics devices with challenging properties including power splitters with uncommon splitting ratios,a TE mode converter,and a broadband power splitter.These devices are free of the features beyond the capability of photolithography and generally in compliance with silicon photonics fabrication design rules.

Ultra-high-linearity integrated lithium niobate electro-optic modulators

Integrated lithium niobate(LN)photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties,low optical loss,and excellent scalability.A key enabler for such systems is a highly linear electro-optic modulator that could faithfully convert analog electrical signals into optical signals.In this work,we demonstrate a monolithic integrated LN modulator with an ultra-high spurious-free dynamic range(SFDR)of 120.04 dB·Hz^(4/5)at 1 GHz,using a ring-assisted Mach–Zehnder interferometer configuration.The excellent synergy between the intrinsically linear electro-optic response of LN and an optimized linearization strategy allows us to fully suppress the cubic terms of third-order intermodulation distortions(IMD3)without active feedback controls,leading to∼20 dB improvement over previous results in the thin-film LN platform.Our ultra-high-linearity LN modulators could become a core building block for future large-scale functional microwave photonic integrated circuits by further integration with other high-performance components like low-loss delay lines,tunable filters,and phase shifters available on the LN platform.