Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber laser at 2.8 {\mu}m

TL;DR

This paper demonstrates the first use of black phosphorus as a saturable absorber to achieve Q-switching in a 2.8 μm Er:ZBLAN fiber laser, resulting in a pulsed laser with high power and short pulse duration.

Contribution

The study introduces black phosphorus as a novel saturable absorber for mid-infrared fiber lasers, enabling Q-switching at 2.8 μm for the first time.

Findings

Achieved Q-switched Er:ZBLAN fiber laser at 2.8 μm with 485 mW average power.

Measured modulation depth of 15% and saturation fluence of 9 μJ/cm² for black phosphorus.

Produced pulses with 1.18 μs width at 63 kHz repetition rate.

Abstract

Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multi-layer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 {\mu}m. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 {\mu}J/cm2, respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 {\mu}J and pulse width of 1.18 {\mu}s at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-{\mu}m fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.