Spontaneous laser line sweeping in bi-directional ring thulium fiber laser

TL;DR

This paper reports the first observation of spontaneous bi-directional laser line sweeping in a thulium-doped fiber laser, demonstrating self-sweeping behavior with switchable modes and potential applications in tunable laser sources.

Contribution

It introduces the novel phenomenon of self-sweeping in a bi-directional ring thulium fiber laser, expanding understanding of laser dynamics and mode control in this wavelength region.

Findings

Self-sweeping occurs spontaneously in both directions.

Sweep rate up to 0.2 nm/s with a 15 nm range.

Switchable between mode with microsecond pulses and static wavelength.

Abstract

We report a phenomenon of self-sweeping in a bi-directional ring thulium-doped fiber laser, for the first time. The laser is spontaneously sweeping in both directions at a rate up to 0.2 nm/s with 15 nm sweeping range in 1.95 {\mu}m wavelength region. The laser output is switchable between two different working modes: periodical spontaneous laser line sweeping with generation of microsecond pulses in time domain; or static central wavelength with amplitude modulated temporally.