Multilayer black phosphorus as broadband saturable absorber for pulsed lasers from 1 to 2.7 {\mu}m wavelength

TL;DR

This study demonstrates that multilayer black phosphorus acts as an effective broadband saturable absorber for pulsed lasers across 1 to 2.7 micrometers, enabling stable Q-switching at multiple wavelengths.

Contribution

It provides the first experimental evidence of broadband saturable absorption of multilayer black phosphorus from 1 to 2.7 micrometers for pulsed laser applications.

Findings

Achieved stable Q-switching at 1.03, 1.93, and 2.72 micrometers.

Black phosphorus shows advantages over TMDs at long wavelengths.

Broadband absorption demonstrated from 1 to 2.7 micrometers.

Abstract

It attracts wide interest to seek universe saturable absorber covering wavelengths from near infrared to mid-infrared band. Multilayer black phosphorus, with variable direct bandgap (0.3-2 eV) depending on the layer number, becomes a good alternative as a universe saturable absorber for pulsed lasers. In this contribution, we first experimentally demonstrated broadband saturable absorption of multilayer black phosphorus from 1 {\mu}m to 2.7 {\mu}m wavelength. With the as-fabricated black phosphorus nanoflakes as saturable absorber, stable Q-switching operation of bulk lasers at 1.03 {\mu}m, 1.93 {\mu}m, 2.72 {\mu}m were realized, respectively. In contrast with large-bandgap semiconducting transition metal dichalcogenides, such as MoS2, MoSe2, multilayer black phosphorus shows particular advantage at the long wavelength regime thanks to its narrow direct bandgap. This work will open promising optoelectronic applications of black phosphorus in mid-infrared spectral region and further demonstrate that BP may fill the gap of between zero-bandgap graphene and large-bandgap TMDs.