High output mode-locked laser empowered by defect regulation in 2D Bi2O2Se saturable absorber

Abstract

Atomically thin Bi2O2Se 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 Bi2O2Se nanoplates as a saturable absorber (SA). Upon further defect regulation in 2D Bi2O2Se, 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+ plasma treatments are employed to precisely regulate the O and Se defect states in Bi2O2Se 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−2 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.

InP/ZnSeS/ZnS Core–Shell Quantum Dots as Novel Saturable Absorbers in Mode‐Locked Fiber Lasers

“…The results show that HF treatment can effectively reduce the defects of QDs and shorten the carrier recovery time, therefore the mode‐locking pulse width is successfully reduced from 635 to 450 fs. This is different from some reported 2D SA materials such as MoS 2 , [ 31,32 ] WS 2 , [ 33,34 ] and Bi 2 O 2 Se, [ 35 ] which can reduce the carrier recovery time by increasing the defect density, which is conducive to reducing the pulse width. Our study will inspire new applications of InP QDs in ultrafast photonics and nonlinear optics.…”

Broadband Nonlinear Response and Ultrafast Photonics Applications in Few-Layer MBene

“…Nonlinear optical (NLO) materials are critical to the development of advanced photonic technologies such as laser optics, all-optical devices, signal processing, higher harmonics, and terahertz generation. 1,2 Two-dimensional (2D) materials have magical structures that lead to their unique electronic, optical, and mechanical properties, satisfying the growing demands for small size, strong response, high efficiency, compactness, and broadband in NLO materials. 2,3 Graphene, the pioneer of 2D material, has been extensively studied as an NLO material for various photonic devices.…”

“…Nonlinear optical (NLO) materials are critical to the development of advanced photonic technologies such as laser optics, all-optical devices, signal processing, higher harmonics, and terahertz generation. , Two-dimensional (2D) materials have magical structures that lead to their unique electronic, optical, and mechanical properties, satisfying the growing demands for small size, strong response, high efficiency, compactness, and broadband in NLO materials. , Graphene, the pioneer of 2D material, has been extensively studied as an NLO material for various photonic devices. , Subsequently, a series of 2D materials in the phase of metallic and semiconductor, such as topological insulators (e.g., Bi 2 Se 3 , Sb 2 Te 3 , and Bi 2 Te 3 ), transition metal dichalcogenides (e.g., MoS 2 and WS 2 ), and black phosphorus (BP), have been demonstrated to exhibit fascinating NLO characteristics …”

Zirconium pentatelluride saturable absorber for solid-state ultrafast lasers

“…For the 2 m solid-state laser, only graphene as a 2D material SA has achieved CWML laser operation, but the obtained average output power is lower due to graphene's low damage threshold. Just now, Liu et al used a Bi2O2Se SA to achieve a 2 m solid-state CWML laser operation, with the average output power of 50 mW [9]. Meanwhile, there is no report on the 3 m passively mode-locked solid-state laser based on 2D materials SA.…”