A low repetition rate optical frequency comb

TL;DR

This paper demonstrates a low-noise, low repetition rate infrared optical frequency comb at 40 kHz using a Yb:KYW laser, pulse picking, and amplification, with potential benefits for nonlinear conversion and precision spectroscopy.

Contribution

It introduces a novel method to generate a low-noise, low repetition rate optical frequency comb with active stabilization and phase noise characterization.

Findings

Achieved a 40 kHz repetition rate frequency comb

Confirmed comb structure via beat note with reference laser

Measured rms phase noise of 195 mrad from 20 Hz to 20 kHz

Abstract

Reducing the pulse repetition rate of an optical frequency comb increases the pulse energy for a given average power. This enhances the efficiency of nonlinear frequency conversion and it facilitates extending the accessible wavelength range, for example into the extreme ultraviolet (XUV). The resulting spectrally dense frequency comb can still be used for precision spectroscopy of narrow atomic or molecular transitions. In this article, we demonstrate a low-noise infrared frequency comb with a repetition rate as low as 40 kHz using a Yb:KYW mode-locked laser, pulse picking, and subsequent amplification. The frequency comb structure is confirmed by generating a beat note with a continuous wave reference laser. A comb mode is actively stabilized to the reference laser, and the integrated rms phase noise from 20 Hz to 20 kHz is measured to be 195 mrad.