Laser frequency stabilization by combining modulation transfer and frequency modulation spectroscopy

TL;DR

This paper introduces a hybrid laser frequency stabilization technique that combines modulation transfer and frequency modulation spectroscopy, achieving improved long-term and short-term stability for cesium D2 transition lasers.

Contribution

A novel hybrid stabilization method combining MTS and FMS error signals, enhanced with laser intensity stabilization, for better laser frequency stability.

Findings

Long-term stability of 7.8 kHz over 10 hours

Short-term stability of 1.9 kHz at 2 seconds

Effective combination of MTS and FMS error signals

Abstract

We present a hybrid laser frequency stabilization method combining modulation transfer spectroscopy (MTS) and frequency modulation spectroscopy (FMS) for the cesium D2 transition. In a typical pump-probe setup, the error signal is a combination of the DC-coupled MTS error signal and the AC-coupled FMS error signal. This combines the long-term stability of the former with the high signal-to-noise ratio of the latter. In addition, we enhance the long-term frequency stability with laser intensity stabilization. By measuring the frequency difference between two independent hybrid spectroscopies, we investigate the short-term and long-term stability. We find a long-term stability of 7.8 kHz characterized by a standard deviation of the beating frequency drift over the course of 10 hours, and a short-term stability of 1.9 kHz characterized by an Allan deviation of that at 2 seconds of integration time.