# Intensity Noise Optimization of a Mid-Infrared Frequency Comb Difference Frequency Generation Source

## TL;DR

This paper investigates how the temporal overlap of pump and signal pulses affects the intensity noise in a mid-infrared frequency comb source and demonstrates active stabilization to optimize noise performance.

## Contribution

It introduces an experimental method to optimize and stabilize the intensity noise in a mid-infrared frequency comb source through active feedback control.

## Key findings

- Identified a RIN minimum at specific pulse delay with 20 fs width
- Achieved a 20 dB RIN increase at 40 fs delay from the minimum
- Enhanced mid-infrared absorption spectra signal-to-noise ratio through stabilization

## Abstract

We experimentally demonstrate in a difference-frequency generation mid-infrared frequency comb source the effect of temporal overlap between pump- and signal- pulse to the relative intensity noise (RIN) of the idler pulse. When scanning the temporal delay between our 130 fs long signal- and pump pulses, we observe a RIN minimum with a 3 dB width of 20 fs delay and an RIN increase of 20 dB in 40 fs delay at the edges of this minimum. We also demonstrate active long-term stabilization of the mid-infrared frequency comb source to the temporal overlap setting corresponding to the lowest RIN operation point by an on-line RIN-detector and active feedback control of the pump-signal- pulse delay. This active stabilization set-up allowed us to dramatically increase the signal-to-noise ratio of mid-infrared absorption spectra.