Boost Lasing Performances of 2D Semiconductor in a Hybrid Tungsten Diselenide Monolayer/Cadmium Selenide Quantum Dots Microcavity Laser

Abstract

direct bandgap, and large exciton-binding energy. Due to these features, they are suitable for use in advanced light sources, [1][2][3][4][5] such as low-threshold lasers operated at room temperature, [6][7][8][9][10][11][12][13][14] polaritonic devices, [15][16][17][18] single-photon emitters, [19][20][21] and valleytronic devices. [22][23][24][25][26] The lasing behavior of several microcavities or nanocavities with a TMDC gain medium has been explored. These studies applied various TMDCs to microdisks, [7,27,28] microspheres, [8] photonic crystals, [6,[9][10][11][12][13] distributed Bragg reflectors, [14] gratings, [29] and plasmonic cavities. [30] Photon emissions from cavities integrated with various TMDC gain media can cover a wide range of wavelengths (from visible to near-infrared) at room temperature. [31] These novel TMDC lasers have various potential applications, including in optical sensors and advanced photon sources for quantum communication, because of their large area-to-volume ratio and nonclassical photon emission. These characteristics are due to the unique band structure of these atomically thin materials. In demonstrations of TMDC lasers, only certain TMDC species [6][7][8][9][10]12,14,27,30] and two types of TMDC interlayer exciton emission [13,29] have been employed as gain media, limiting the lasing wavelength to the gain window of the selected TMDCs. Monolayer (ML) transition metal dichalcogenides (TMDCs) are suitable for use in low-threshold, room-temperature lasers. 2D semiconductor lasers are coherent, compact, and are suitable for multispectral light sources. 0D quantum dot technology has been applied in broadband-emitting devices and high-quality display systems. Herein, dual-color continuous-wave microcavity lasers are investigated by integrating a tungsten diselenide (WSe 2 ) monolayer and cadmium selenide (CdSe) quantum dots (QDs) into a single microdisk cavity. The hybrid TMDC/QD microcavity device not only achieves lasing in two distinct wavelength regions but also boosts the lasing performances of the WSe 2 monolayer due to the energy conversion between the two gain materials. Variations in the spectra obtained under power-dependent lasing are examined, and the temporal coherence properties of the lasing signals are also characterized to verify the lasing actions. The results indicate that the lasing threshold of the 2D WSe 2 monolayer cavity with the CdSe QDs is reduced by more than 2.5 times compared with the WSe 2 cavity without the QDs. These findings both expand the wavelength range of TMDC-based compact lasers at room temperature and facilitate their implementation in applications such as photonic integrated circuits, broadband light-emitting diodes, and quantum display systems.