High-Power Quantum-Limited Photodiode and Classical Laser Noise Squashing

TL;DR

This paper introduces a lead-compensated photodetector capable of quantum-limited readout at high power levels and demonstrates classical noise suppression of a fiber laser to the shot noise limit over a broad bandwidth.

Contribution

We developed a simple, high-power, quantum-limited photodetector and applied feedback to squash classical laser noise effectively over a wide frequency range.

Findings

Achieved quantum-limited detection from 0.3 mW to 10 mW power levels.

Successfully suppressed laser amplitude noise to shot noise limit.

Maintained laser linewidth despite noise suppression.

Abstract

To benefit high-power interferometry and the creation of low-noise light sources, we develop a simple lead-compensated photodetector enabling quantum-limited readout from 0.3 mW to 10 mW and 10 k$\Omega$ transimpedance gain from 85 Hz - 35 MHz. Feeding the detector output back to an intensity modulator, we squash the classical amplitude noise of a commercial 1550 nm fiber laser to the shot noise limit over a bandwidth of 700 Hz - 200 kHz, observing no degradation to its (nominally ~100 Hz) linewidth.