Single‐crystalline indium selenide fibers by laser‐induced recrystallization and their tunable whispering‐gallery‐mode lasing by pressure‐modulating

Abstract

AbstractIndium selenide (InSe) crystal, as an emerging Van der Waals semiconductor, showed great potential in optical and optoelectronic devices due to its remarkable electron mobility, flexible direct bandgap, and photoresponsivity. Especially, the bulk single‐crystalline InSe shows superplastic deformability with the aid of the interlayer gliding and cross‐layer dislocation slip. The extraordinary mechanical behavior brings significant opportunities and possibilities to pressure‐modulated optical devices, which, however, have not been explored sufficiently. Additionally, InSe crystals are challenged in the rapid large‐scale preparation and reproduction due to limitations, such as phase heterogeneity, dissociation risks, and chemical instability. Herein, we proposed a fiber drawing technique to create single‐crystalline InSe by the molten core drawing method combined with CO2 laser‐induced recrystallization. The fabricated InSe fiber, spanning several meters in length, shows a uniform and directional single‐crystalline InSe core encased within a 450 µm thick protective borosilicate glass cladding. The inherent core‐cladding configuration of the InSe fibers not only provides robust protection to the InSe crystals but also seamlessly creates a whispering‐gallery‐mode microcavity. Utilizing a 532 nm nanosecond pulsed laser as a pump, a tunable lasing from 1076.2 to 1111.8 nm was achieved, dictated by the controlled pressure within the InSe fiber. We present a simple and effective method for single‐crystalline InSe fabrication and first achieve a pressure‐modulated laser in a near‐infrared band based on InSe fiber, heralding an advancement for the scalable, efficient generation of tunable lasers.