Broadband rhenium disulfide optical modulator for solid-state lasers

Abstract

Rhenium disulfide (ReS 2 ), a member of group VII transition metal dichalcogenides (TMDs), has attracted increasing attention because of its unique distorted 1T structure and electronic and optical properties, which are much different from those of group VI TMDs (MoS 2 , WS 2 , MoSe 2 , WSe 2 , etc.). It has been proved that bulk ReS 2 behaves as a stack of electronically and vibrationally decoupled monolayers, which offers remarkable possibilities to prepare a monolayer ReS 2 facilely and offers a novel platform to study photonic properties of TMDs. However, due to the large and layer-independent bandgap, the nonlinear optical properties of ReS 2 from the visible to midinfrared spectral range have not yet been investigated. Here, the band structure of ReS 2 with the introduction of defects is simulated by the ab initio method, and the results indicate that the bandgap can be reduced from 1.38 to 0.54 eV with the introduction of defects in a suitable range. In the experiment, using a bulk ReS 2 with suitable defects as the raw material, a few-layered broadband ReS 2 saturable absorber (SA) is prepared by the liquid phase exfoliation method. Using the as-prepared ReS 2 SA, passively Q-switched solid-state lasers at wavelengths of 0.64, 1.064, and 1.991 μm are investigated systematically. Moreover, with cavity design, a femtosecond passively modelocked laser at 1.06 μm is successfully realized based on the as-prepared ReS 2 SA for the first time. The results present a promising alternative for a rare broadband optical modulator and indicate the potential of ReS 2 in generating Q-switched and mode-locked pulsed lasers. It is further anticipated that this work may be helpful for the design of 2D optoelectronic devices with variable bandgaps.

2D Layered Materials: Synthesis, Nonlinear Optical Properties, and Device Applications

“…Since 2010, Q‐switched solid‐state lasers based on layered materials including graphene, topological insulators, TMDCs, BP, and g‐C 3 N 4 , have been developed rapidly, as shown in Table . It can be seen that these lasers have excellent performance in output power, pulse width, repetition rate, and peak power.…”

Recent Progress in 2D Material‐Based Saturable Absorbers for All Solid‐State Pulsed Bulk Lasers

“…Moreover, its bandgap does not change significantly with variation in thickness (1.43 eV for monolayer and 1.35 eV for bulk) . By using a ReS 2 SA, our group demonstrated a passively Q‐switched Pr:YLiF 4 laser operating at 640 nm with an average output power of 52 mW and a minimum pulse duration of 160 ns . For TMD SA‐based mode‐locking visible lasers, only MoS 2 has been reported to be successful .…”

“…b) CW mode‐locked Yb:CALGO laser with ReS 2 SA: the absorbance and Z‐scan measurement data of ReS 2 SA; the experimental setup of the mode‐locked laser; the pulse train, single pulse profile, and output spectrum of mode‐locked laser pulse. Reproduced with permission . Copyright 2018, OSA Publishing.…”

“…Based on the ab initio method, the calculated results indicated that by introducing S vacancy defects in an appropriate range, the bandgap of ReS 2 can be tuned from 1.38 to 0.56 eV, corresponding to absorption wavelengths ranging from 0.9 to 2.2 µm. By using the as‐prepared ReS 2 SAs, we demonstrated a 1.06 µm mode‐locked solid‐state bulk laser with a pulse width as short as 323 fs (the shortest mode‐locked bulk laser pulse in the 1.0 µm wavelength range) and an output power of 350 mW (Figure b) …”

Visible-wavelength pulsed lasers with low-dimensional saturable absorbers

“…By managing the number of layers of TMD samples, their nonlinear absorption properties can be accurately controlled, making this kind of nanomaterial more suitable for pulse generation in the visible spectral range. TMDs including MoS 2 , SnS 2 , WS 2 , and ReS 2 have been deeply exploited as excellent SAs in visible pulsed lasers [174][175][176][177][178][179]. For example, MoS 2 with fewer than 10 layers was transferred onto a quartz glass, which acted as the SA in the solid-state crystal lasers and successfully generated pulsed operation at 532, 605, 639, and 721 nm.…”