# Generation mode-locked square-wave pulse based on reverse saturable absorption effect in graded index multimode fiber

## TL;DR

This paper demonstrates a novel mode-locked square-wave pulse generation in a Yb-doped graded index multimode fiber laser utilizing reverse saturable absorption, with tunable pulse widths and high mode stability.

## Contribution

It introduces the first demonstration of mode-locked square-wave pulses in this fiber laser configuration based on reverse saturable absorption effects.

## Key findings

- Pulse width tunable from 350 ps to 52.6 ns
- Supermode suppression ratio exceeds 65 dB
- Spectrum bandwidth of 0.73 nm

## Abstract

We firstly report mode-locked square-wave pulse in Yb-doped fiber laser based on graded index multimode fiber of reverse suturable absorption. By adjusting the pump power, the width of the square-wave can be tuned range from 350 ps to 52.6 ns with 3dB bandwidth spectrum of 0.73 nm. The supermode suppression ratio exceeds ~ 65 dB, which indicates excellent mode-locked operation state, and we also study the characteristic of pulse by the chirp measurement system. The mode-locked square-wave pulse fiber laser can sever as high power light source for industrial applications.

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Source: https://tomesphere.com/paper/1904.06706