Up to 50 dB Extinction in Broadband Single-Stage Thermo-Optic Mach-Zehnder Interferometers for Programmable Low-Loss Silicon Nitride Photonic Circuits

We demonstrate single-stage thermo-optic Si
3
N
4
interferometers with (46.1±2.5) dB average extinction ratio over 1460-1640 nm (≈50× of typical devices). We analyze performance requirements for creating reconfigurable high-quality-factor resonators in programmable circuits using such interferometers.