Self-started unidirectional operation of a fiber ring soliton laser without an isolator

TL;DR

This paper demonstrates a fiber ring soliton laser that self-starts unidirectional operation without needing an isolator, using nonlinear polarization rotation for mode-locking, showing comparable features to traditional designs.

Contribution

It introduces a method for achieving self-started unidirectional mode-locking in a fiber laser without an isolator, leveraging intrinsic nonlinearity discrimination.

Findings

Laser operates unidirectionally without an isolator.

Mode-locking achieved via nonlinear polarization rotation.

Laser features are comparable to traditional unidirectional lasers.

Abstract

We demonstrate self-started mode-locking in an Erbium-doped fiber ring laser by using the nonlinear polarization rotation mode-locking technique but without an isolator in cavity. We show that due to the intrinsic effective nonlinearity discrimination of the mode-locked pulse propagating along different cavity directions, the soliton operation of the laser is always unidirectional, and its features have no difference to that of the unidirectional lasers with an isolator in cavity.