# Equalization of pulse timings in an excitable microlaser system with delay

## TL;DR

This study demonstrates that an excitable microlaser with delayed feedback stabilizes pulse timing into periodic orbits, with potential implications for photonics and neuroscience, by experimentally and numerically analyzing long-term behavior.

## Contribution

It reveals long-term stable periodic regimes with equalized pulse timings in an excitable microlaser system, expanding understanding of feedback-induced dynamics.

## Key findings

- System settles into stable periodic orbits with equalized pulse timing.
- Multiple periodic regimes can coexist and be accessed via external pulses.
- Timing equalization is driven by excitability combined with delayed feedback.

## Abstract

An excitable semiconductor micropillar laser with delayed optical feedback is able to regenerate pulses by the excitable response of the laser. It has been shown that almost any pulse sequence can, in principle, be excited and regenerated by this system over short periods of time. We show experimentally and numerically that this is not true anymore in the long term: rather, the system settles down to a stable periodic orbit with equalized timing between pulses. Several such attracting periodic regimes with different numbers of equalized pulse timing may coexist and we study how they can be accessed with single external optical pulses of sufficient strength that need to be timed appropriately. Since the observed timing equalization and switching characteristics are generated by excitability in combination with delayed feedback, our results will be of relevance beyond the particular case of photonics, especially in neuroscience.