Laser Phase and Frequency Stabilization Using Atomic Coherence

TL;DR

This paper introduces a new method for stabilizing laser phase and frequency using atomic coherence, which enhances laser linewidth stability and benefits atomic clock and magnetometer applications.

Contribution

The paper proposes a novel polarization spectroscopy technique utilizing atomic coherence as a phase memory, differing from traditional cavity-based stabilization methods.

Findings

Achieved laser linewidth reduction from 2 MHz to 20 kHz

Demonstrated shot-noise-limited linewidth stabilization

Potential improvements for atomic clocks and magnetometers

Abstract

We present a novel and simple method of stabilizing the laser phase and frequency by polarization spectroscopy of an atomic vapor. In analogy to the Pound-Drever-Hall method, which uses a cavity as a memory of the laser phase, this method uses atomic coherence (dipole oscillations) as a phase memory of the transmitting laser field. A preliminary experiment using a distributed feedback laser diode and a rubidium vapor cell demonstrates a shot-noise-limited laser linewidth reduction (from 2 MHz to 20 kHz). This method would improve the performance of gas-cell-based optical atomic clocks and magnetometers and facilitate laser-cooling experiments using narrow transitions.