High‐β Lasing in Self‐Assembled Photonic‐Defect Microcavities with a Transition Metal Dichalcogenide Monolayer as Active Material

• Published in: Laser & photonics reviews 2024-11, Vol.18 (11), p.n/a
• Main Authors: Koulas‐Simos, Aris, Palekar, Chirag C., Gaur, Kartik, Limame, Imad, Shih, Ching‐Wen, Rosa, Bárbara L.T., Ning, Cun‐Zheng, Reitzenstein, Stephan
• Format: Article
• Language: English
• Subjects: Air bubbles; Boron nitride; Bragg reflectors; Chalcogenides; Defects; Encapsulation; light‐matter interaction; Microcavities; Microlasers; micro‐ and nanolasers; Monolayers; Optical properties; Photonics; photonic‐defect microcavities; Selenides; Self-assembly; self‐assembled; Transition metal compounds; transition‐metal dichalcogenides; Tungsten compounds
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.202400271

The investigation and development of innovative micro‐ and nanolasers using transition metal dichalcogenide (TMDC) monolayers as active materials is attracting considerable attention due to their unique electrical, mechanical, and optical properties. In this report, the fabrication of photonic‐defect microcavities that are self‐assembled and integrated into a dielectric distributed Bragg reflector structure that fully encapsulates a monolayer of tungsten diselenide (WSe2${\rm WSe}_2$) is detailed. The encapsulation process of the WSe2${\rm WSe}_2$ monolayer with hexagonal boron nitride generates air bubbles that induce parabolic photonic defects in the microcavity. These defects lead to a tight diameter‐dependent three‐dimensional optical confinement, which is confirmed by experimental studies and numerical simulations. In addition, a significant nonlinearity in the input‐output characteristics and excitation‐power‐dependent linewidth narrowing is observed in the resonators, indicating laser operation, which is verified by photon autocorrelation measurements. The photonic‐defect cavities are all formed on a single monolayer sample, suggesting potential advantages for multi‐wavelength emission photonic applications and facilitating TMDC‐based prestructured photonic‐defect microlasers for large‐scale fabrication. Spontaneously formed air bubbles during the stacking of a tungsten diselenide monolayer and a hexagonal boron nitride flake create a photonic‐defect cavity in the deposited top dielectric distributed Bragg reflector, circumventing the necessity of etching for lateral confinement. Power‐dependent optical and second‐order coherence measurements unambiguously validate a high‐β$\beta$ microlaser and highlight the potential for deterministic fabrication of transition‐metal‐dichalcogenide‐based photonic‐defect micro‐ and nanolasers.