Octave-spanning frequency comb generation in a silicon nitride chip

TL;DR

This paper demonstrates an octave-spanning frequency comb generated in a silicon nitride chip using cascaded four-wave mixing, with tunable spacing and low-noise operation, advancing integrated photonic frequency comb technology.

Contribution

It introduces a monolithic silicon nitride microring resonator capable of generating a broad, octave-spanning frequency comb with tunable spacing and low-noise characteristics.

Findings

Frequency comb spans 128 THz with 226 GHz spacing

Comb operates in a low-noise state with 30-dB noise reduction

Tuning of comb spacing achieved via pump power adjustment

Abstract

We demonstrate a frequency comb spanning an octave via the parametric process of cascaded four-wave mixing in a monolithic, high-Q silicon nitride microring resonator. The comb is generated from a single-frequency pump laser at 1562 nm and spans 128 THz with a spacing of 226 GHz, which can be tuned slightly with the pump power. In addition, we investigate the RF-noise characteristics of the parametric comb and find that the comb can operate in a low-noise state with a 30-dB reduction in noise as the pump frequency is tuned into the cavity resonance.