Timing jitter of passively mode-locked semiconductor lasers subject to optical feedback; a semi-analytic approach

TL;DR

This paper introduces a semi-analytical method to efficiently calculate timing jitter in passively mode-locked semiconductor lasers affected by optical feedback, revealing how feedback parameters influence jitter reduction.

Contribution

It presents a novel semi-analytical approach that reduces computation time and predicts how optical feedback parameters affect pulse timing jitter in these lasers.

Findings

Resonant feedback reduces timing jitter.

Frequency-pulling regions form around resonances.

Jitter decreases approximately as 1/τ for long delays.

Abstract

We propose a semi-analytical method of calculating the timing fluctuations in mode-locked semiconductor lasers and apply it to study the effect of delayed coherent optical feedback on pulse timing jitter in these lasers. The proposed method greatly reduces computation times and therefore allows for the investigation of the dependence of timing fluctuations over greater parameter domains. We show that resonant feedback leads to a reduction in the timing jitter and that a frequency-pulling region forms about the main resonances, within which a timing jitter reduction is observed. The width of these frequency-pulling regions increases linearly with short feedback delay times. We derive an analytic expression for the timing jitter, which predicts a monotonous decrease in the timing jitter for resonant feedback of increasing delay lengths, when timing jitter effects are fully separated from amplitude jitter effects. For long feedback cavities the decrease in timing jitter scales approximately as $1/\tau$ with the increase of the feedback delay time $\tau$.