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 facilitate efficient nonlinear conversion and enable wavenumber-accurate selection of converted optical modes, but they do not support post-fabrication reconfiguration of these operational modes. Coupled-ring resonators, on the other hand, allow post-fabrication reconfiguration but suffer from ambiguity in mode selectivity. We propose a 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 thermo-optic 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-free spectral range stepwise manner and in a gap-free continuous manner, achieving a broad optical frequency tuning range of and a conversion efficiency of >5THz. This approach introduces design flexibility, as well as high and precise reconfigurability, to integrated nonlinear photonics, providing a pathway toward future high-performance on-chip nonlinear light sources.