Broadband and Accurate Electric Tuning of On-Chip Efficient Nonlinear Parametric Conversion

Abstract

On-chip nonlinear photonic conversion functions with wide and precise tunability as well as high conversion efficiency are highly desirable for a wide range of applications. Photonic crystal micro-ring resonators (PhCR) facilitate efficient nonlinear conversion and enable wavenumber-accurate selection of converted optical modes, but do not support post-fabrication reconfiguration of these operational modes. Coupled-ring resonators, on the other hand, allows post-fabrication reconfiguration but suffers from ambiguity in mode selectivity. We propose a novel segmented photonic crystal micro-ring resonator featuring half-circumference gratings that decouples the locking between the grating Bragg reflection peak and micro-ring resonance frequencies. By introducing complementary thermos-optical controllers that allow differential tuning between the grating reflection peak and the micro-ring resonance, the device supports electrically reconfigurable wavenumber-accurate optical mode selectivity, experimentally demonstrated as a voltage-tunable, power-efficient optical parametric oscillator. The device demonstrates electric tuning of signal and idler frequencies both in a per-FSR stepwise manner and in a gap-free continuous manner, achieving a broad optical frequency tuning range of > 5 THz and a conversion efficiency of >25%. The novel approach introduces unprecedented design flexibility as well as high and precise reconfigurability to integrated nonlinear photonics, providing a new pathway towards future high-performance on-chip nonlinear light sources.