Resonance vector mode locking

TL;DR

This paper introduces a novel resonance vector self-mode locking mechanism in fiber lasers, enabling linewidth narrowing to Hz range and simplifying phase control, with potential applications across various scientific fields.

Contribution

It demonstrates for the first time experimentally and theoretically a new mode locking mechanism using resonance vector effects and acoustic phonons in fiber lasers.

Findings

Achieved linewidth narrowing down to Hz range.

Demonstrated resonance phase locking of sidebands with longitudinal modes.

Enabled tunability of repetition rate via acoustic phonons.

Abstract

A mode locked fibre laser as a source of ultra-stable pulse train has revolutionised a wide range of fundamental and applied research areas by offering high peak powers, high repetition rates, femtosecond range pulse widths and a narrow linewidth. However, further progress in linewidth narrowing seems to be limited by the complexity of the carrier-envelope phase control. Here for the first time we demonstrate experimentally and theoretically a new mechanism of resonance vector self-mode locking where tuning in-cavity birefringence leads to excitation of the longitudinal modes sidebands accompanied by the resonance phase locking of sidebands with the adjacent longitudinal modes. An additional resonance with acoustic phonons provides the repetition rate tunability and linewidth narrowing down to Hz range that drastically reduces the complexity of the carrier-envelope phase control and so will open the way to advance lasers in the context of applications in metrology, spectroscopy, microwave photonics, astronomy, and telecommunications.