Passive Laser Power Stabilization via an Optical Spring

TL;DR

This paper demonstrates a passive method using the optical spring effect to significantly reduce laser power noise, surpassing traditional active stabilization limits, with potential applications in precision metrology and gravitational wave detection.

Contribution

It introduces a passive stabilization technique based on the optical spring effect, achieving noise reduction beyond shot noise limits of active schemes.

Findings

Power noise reduced by a factor of 125

Effective stabilization bandwidth from 400 Hz to 100 kHz

Passive stabilization surpasses shot noise limitations

Abstract

Metrology experiments can be limited by the noise produced by the laser involved via small fluctuations in the laser's power or frequency. Typically, active power stabilization schemes consisting of an in-loop sensor and a feedback control loop are employed. Those schemes are fundamentally limited by shot noise coupling at the in-loop sensor. In this letter we propose to use the optical spring effect to passively stabilize the classical power fluctuations of a laser beam. In a proof of principle experiment, we show that the relative power noise of the laser is stabilized from approximately $2 \times 10^{-5}$ Hz$^{-1/2}$ to a minimum value of $1.6 \times 10^{-7}$ Hz$^{-1/2}$, corresponding to the power noise reduction by a factor of $125$. The bandwidth at which stabilization occurs ranges from $400$ Hz to $100$ kHz. The work reported in this letter further paves the way for high power laser stability techniques which could be implemented in optomechanical experiments and in gravitational wave detectors.