Whispering Gallery Mode Lasing with Single Perovskites and Atmospheric Stable Double Perovskites as Gain Medium

Ultrahigh photoluminescence quantum yield (PLQY), low non-radiative recombination, and tunable spectral emission from ultraviolet to the visible range make inorganic lead halide perovskites (LHPs) (APbX₃; A = Rb, Cs and X = Br, I) ideal candidates for optoelectronics and photonics applications. Leveraging these properties, we explore the use of LHP quantum dots (QDs) as gain media in whispering gallery mode (WGM) microlasers, focusing on their potential for efficient and stable lasing. Initially, we demonstrate WGM lasing using CsPbI₃-QDs coated on TiO₂ spherical microcavities. The photoluminescence emission from CsPbI₃-QDs effectively couples with TiO₂ microspherical resonating optical cavities, leading to a switch from spontaneous to stimulated emission above a distinct threshold of 708.7 W/cm² under 632-nm laser excitation. The lasing intensity increases with power density beyond this threshold, achieving quality factors (Q) of up to ~1195 at room temperature.[1] Building on this, we investigate the superior photostability and high PLQY of Cs_0.5Rb_0.5PbBr₃-QDs, selected over CsPbBr₃ and CsPbI₃ due to their enhanced performance. Encapsulating these QDs on TiO₂ microspheres results in WGM lasing with a high Q factor of ~1807 when excited with an Ar-ion laser (λ_ex = 488 nm) at a threshold of 7.98 kW/cm². This system remains photostable even under elevated continuous laser power (~20.03 kW/cm²) for 90 minutes. The high photostability of Cs_0.5Rb_0.5PbBr₃-QDs addresses critical challenges in perovskite microlasers, ensuring consistent performance over extended periods.[2] These findings underscore the potential of inorganic lead halide perovskites, particularly Rb-substituted halide QDs, for developing robust and efficient WGM microlasers. The high-quality factors, significant lasing intensity, and excellent photostability demonstrated in these studies pave the way for their integration into advanced photonic devices, including tunable microlasers, photodetectors, and LEDs. Results on WGM coupling using various compositions of Cs_0.5Rb_0.5PbBr_3-xI_x QDs and its lasing characteristics will be presented. It is well known that double perovskites are a stable alternative to lead-free perovskite structure. The integration of double perovskites on these resonating microspheres will also be discussed.
Reference:
[1] S. Laskar et al. “Whispering Gallery Mode Micro-Lasing in CsPbI₃ Quantum Dots Sensitized TiO₂ Microspherical Cavity Resonator”, Optics Letters, 48(10), 2643-2646 (2023).
[2] S. Laskar et al. “Photostable Cs_0.5Rb_0.5PbBr₃ Quantum Dots for Whispering Gallery Mode Lasing”, ACS Appl. Opt. Mater. 2(8), 1591–1599 (2024)