The development of high-quality, stable, and cost-effective micro/nano dual-band lasing remains a crucial challenge for multifunctional applications. In this study, we demonstrated high-Q dual-band whispering gallery mode lasing in an independent core-shell microdisk, emitting both ultraviolet and blue lasing. The GaN-based microdisk with InGaN/GaN quantum wells served as the core, while a SiO2 layer was deposited on the sidewalls to construct the core-shell microdisk. This independent structure was fabricated using the graphically epitaxial lift-off method, which effectively mitigates light leakage issues associated with the substrate and facilitates flexible device integration. Compared to the microdisk without a SiO2 shell coating, the threshold of ultraviolet lasing in the core-shell microdisk was reduced by 1.6 times, the quality factor (Q-factor) was enhanced by 21.7%, and blue lasing was successfully achieved. The underlying physical mechanisms were thoroughly analyzed through steady-state and time-resolved photoluminescence, along with finite-difference time-domain simulations. Furthermore, cooling from 300 K to 100 K could significantly enhance the lasing performance, increasing the Q-factor by factors of 1.7 and 1.9 in the ultraviolet and blue bands, respectively. Additionally, due to thermal expansion and thermo-optical effects, the blue lasing mode exhibits a temperature-dependent wavelength shift with a slope of −0.007 nm/K. The generation and optimization of dual-band lasing within a single microcavity offer new opportunities for broadband optical communication, high-sensitivity multi-wavelength biosensing, multi-label biomedical imaging, and high-density optical storage.
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