# Q-switched Dy:ZBLAN fiber lasers beyond 3 {\mu}m: comparison of pulse generation using acousto-optic modulation and inkjet-printed black phosphorus

## TL;DR

This paper demonstrates high-energy mid-infrared Q-switched dysprosium-doped fiber lasers beyond 3 μm using acousto-optic modulation and inkjet-printed black phosphorus, highlighting their performance and potential for advanced applications.

## Contribution

First demonstration of high-energy mid-infrared Q-switched dysprosium fiber lasers using two different modulation techniques, including a novel black phosphorus saturable absorber.

## Key findings

- Achieved up to 12 μJ pulse energy with acousto-optic modulation.
- Generated 1.0 μJ pulses using inkjet-printed black phosphorus saturable absorber.
- Identified routes for improving pulse energies and avoiding multi-pulsing through numerical modeling.

## Abstract

We report high-energy mid-infrared pulse generation by Q-switching of dysprosium-doped fiber lasers for the first time. Two different modulation techniques are demonstrated. Firstly, using active acousto-optic modulation, pulses are produced with up to 12 {\mu}J energy and durations as short as 270 ns, with variable repetition rates from 100 Hz to 20 kHz and central wavelengths tunable from 2.97 to 3.23 {\mu}m. Experiments are supported by numerical modeling, identifying routes for improved pulse energies and to avoid multi-pulsing by careful choice of modulator parameters. Secondly, we demonstrate passive Q-switching by fabricating an inkjet-printed black phosphorus saturable absorber, simplifying the cavity and generating 1.0 {\mu}J pulses with 740 ns duration. The performance and relative merits of each modulation approach are then critically discussed. These demonstrations highlight the potential of dysprosium as a versatile gain medium for high-performance pulsed sources beyond 3 {\mu}m.

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Source: https://tomesphere.com/paper/1902.06945