Optical pilot-tone correction of phase errors in photo-detection chains

TL;DR

This paper introduces an optical pilot-tone method to measure and correct phase errors in photodetectors, enhancing phase noise performance and stability for timing-sensitive applications.

Contribution

It presents a novel optical pilot-tone technique for real-time correction of phase errors in photodetection chains, improving accuracy and noise performance.

Findings

Reduced phase walk below 10 mHz

Improved phase noise performance

Enhanced timing accuracy in photodiodes

Abstract

The delay of photodetectors can be affected by intensity, reverse bias, and temperature through different effects. An optical pilot tone superimposed on the detectors allows the independent measurement of such phase errors in the complete photodetection chain and provides an opportunity to correct them. This allows further separate readout noise from the measurement, providing a more performant and intensity-invariant phase readout. We test the functional principle on a setup demonstrating an improved phase noise performance and a reduced phase walk below 10~mHz in particular. This benefits applications which require accurate timing or signal phase determination with photodiodes.