Nonlinear Networks for Arbitrary Optical Synthesis

Abstract

Nonlinear wavelength conversion is a powerful control of light, especially when implemented at the nanoscale with integrated photonics. However, strict energy conservation and phase-matching requirements constrain the converted output. To overcome these constraints and enable novel functionalities, we introduce nonlinear networks - systems of nonlinear photonic elements that observe a programmable set of conservation rules. We highlight the diverse capabilities of nonlinear networks by demonstrating an optical-frequency synthesizer, which operates at nearly arbitrary output frequency exceeding the state of the art in synthesized conversion bandwidth. Using a codesigned microresonator network, our synthesizer is based on four-wave mixing (FWM) spectral translation of a tunable laser and a frequency comb. Energy conservation in FWM provides deterministic synthesis, and it allows a nearly arbitrary frequency tuning range by the dependence of resonant FWM on group-velocity dispersion, temperature, and input laser frequency. Moreover, we take advantage of efficient parametric amplification intrinsic to nonlinear networks. We operate spectral translation across output ranges up to 200 THz, and we characterize the synthesizer through precise metrology, demonstrating <0.1 Hz absolute accuracy. Our experiments introduce nonlinear networks that perform complex functionalities, including optical synthesis with nearly limitless bandwidth.