Generation of tunable, high repetition rate optical frequency combs using on-chip silicon modulators

TL;DR

This paper demonstrates the generation of tunable, high-repetition-rate optical frequency combs on-chip using silicon modulators, achieving continuous tuning and promising bandwidth scaling for integrated photonics applications.

Contribution

It introduces a novel on-chip silicon PN modulator approach for generating stable, tunable frequency combs with high repetition rates and explores bandwidth scaling via simulations.

Findings

Achieved over 8 comb lines in a 20-dB bandwidth in the C-band.

Demonstrated continuous tuning of center frequency and repetition rate from 7.5GHz to 12.5GHz.

Simulations suggest potential for bandwidth scaling with optimized silicon PIN modulators.

Abstract

We experimentally demonstrate tunable, highly-stable frequency combs with high repetition-rates using a single, charge injection based silicon PN modulator. In this work, we demonstrate combs in the C-band with over 8 lines in a 20-dB bandwidth. We demonstrate continuous tuning of the center frequency in the C-band and tuning of the repetition-rate from 7.5GHz to 12.5GHz. We also demonstrate through simulations the potential for bandwidth scaling using an optimized silicon PIN modulator. We find that, the time varying free carrier absorption due to carrier injection, an undesirable effect in data modulators, assists here in enhancing flatness in the generated combs.