A Silicon-Based Monolithic Optical Frequency Comb Source

TL;DR

This paper demonstrates a fully integrated, chip-scale silicon microresonator that generates broad-bandwidth optical frequency combs with high precision, offering a compact and environmentally stable source for advanced photonic applications.

Contribution

It introduces a monolithic silicon-based microresonator for generating broad optical frequency combs, advancing miniaturization and stability in comb sources.

Findings

Achieved nearly an order of magnitude broader bandwidth than previous microresonator combs.

Verified equidistant comb line frequencies using a novel self-referencing method.

Demonstrated potential for ultrafast pulse generation on a chip-scale device.

Abstract

Recently developed techniques for generating precisely equidistant optical frequencies over broad wavelength ranges are revolutionizing precision physical measurement [1-3]. These frequency "combs" are produced primarily using relatively large, ultrafast laser systems. However, recent research has shown that broad-bandwidth combs can be produced using highly-nonlinear interactions in microresonator optical parametric oscillators [4-11]. Such devices not only offer the potential for developing extremely compact optical atomic clocks but are also promising for astronomical spectroscopy [12-14], ultrashort pulse shaping [15], and ultrahigh-speed communications systems. Here we demonstrate the generation of broad-bandwidth optical frequency combs from a CMOS-compatible integrated microresonator [16,17], which is a fully-monolithic and sealed chip-scale device making it insensitive to the surrounding environment. We characterize the comb quality using a novel self-referencing method and verify that the comb line frequencies are equidistant over a bandwidth that is nearly an order of magnitude larger than previous measurements. In addition, we investigate the ultrafast temporal properties of the comb and demonstrate its potential to serve as a chip-scale source of ultrafast (sub-ps) pulses.