Mode-locked fiber laser with offset splicing between two multimode fibers as a saturable absorber

TL;DR

This paper introduces a novel fiber laser design using offset splicing of multimode fibers as a saturable absorber, achieving stable mode-locking with promising performance for ultrafast applications.

Contribution

It presents a new method of mode-locking fiber lasers via offset splicing of graded index multimode fibers, demonstrating a simple, low-cost, and effective saturable absorber mechanism.

Findings

Achieved stable mode-locking at 1039 nm with 17.6 ps pulses

Saturable absorber with 2.8% modulation depth and 2.5 MW/cm2 saturation intensity

High signal-to-noise ratio of 65 dB in laser output

Abstract

A novel mode-locked fiber laser based on offset splicing technology between two kinds of graded index multimode fibers is proposed and experimentally demonstrated. The offset splice spot structure acts as a saturable absorber via nonlinear multimodal interference mechanism. The absorption modulation depth of the device is 2.8%, with a saturation intensity of 2.5 MW/cm2. The fiber laser operates at a stable mode-locked state when the pump power reaches 114 mW. The laser oscillates at 1039 nm with a pulsewidth of 17.6 ps, a repetition rate of 32.619 MHz, and a high signal noise ratio of 65 dB. The fiber laser is superior in terms of low cost, high damage threshold, and easy fabrication, thus providing many potential applications in ultrafast photonics and industrial processing.