High output mode-locked laser empowered by defect regulation in 2D Bi<sub>2</sub>O<sub>2</sub>Se saturable absorber.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35790761.
- Also identified by DOI 10.1038/s41467-022-31606-8 and PMC identifier 9256711.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Atomically thin Bi<sub>2</sub>O<sub>2</sub>Se has emerged as a novel two-dimensional (2D) material with an ultrabroadband nonlinear optical response, high carrier mobility and excellent air stability, showing great potential for the realization of optical modulators. Here, we demonstrate a femtosecond solid-state laser at 1.0 µm with Bi<sub>2</sub>O<sub>2</sub>Se nanoplates as a saturable absorber (SA). Upon further defect regulation in 2D Bi<sub>2</sub>O<sub>2</sub>Se, the average power of the mode-locked laser is improved from 421 mW to 665 mW, while the pulse width is decreased from 587 fs to 266 fs. Moderate Ar<sup>+</sup> plasma treatments are employed to precisely regulate the O and Se defect states in Bi<sub>2</sub>O<sub>2</sub>Se nanoplates. Nondegenerate pump-probe measurements show that defect engineering effectively accelerates the trapping rate and defect-assisted Auger recombination rate of photocarriers. The saturation intensity is improved from 3.6 ± 0.2 to 12.8 ± 0.6 MW cm<sup>-2</sup> after the optimized defect regulation. The enhanced saturable absorption and ultrafast carrier lifetime endow the high-performance mode-locked laser with both large output power and short pulse duration.