The whispering gallery mode (WGM) microcavity has a high-quality factor and small mode volume, for the property of confining photons in a small volume for a long time, which enhances the light-matter interaction. Combining with quantum dots that act as gain medium, it can realize low-threshold and narrow-linewidth microlasers with excellent performance. However, achieving conventional whispering gallery mode lasers still requires complex preparation conditions. Here, we report a narrow linewidth whispering gallery mode lasing from all-inorganic perovskite quantum dots (CsPbBr 3 QDs), illustrating facile and cost-effective properties. CsPbBr 3 QDs with excellent properties were synthesized by hot injection method and used as gain media for lasers, and microspheres as optical resonators . The whispering gallery mode laser with a quality factor Q of 4791 and a narrow linewidth of 0.11 nm was obtained at room temperature. The WGM microlaser achieved by this paper could be a great application prospects in biotechnology.
Quasi-bound states in the continuum (QBIC) offering high Q factors possess great value in fields such as sensing, nonlinear optics, and imaging. However, limited by loss in materials and the demanding requirements for accuracy in fabrication, realizing high-quality QBIC devices is challenging in THz, especially at high THz frequencies where conventional materials become more lossy and the dimension of the device shrinks. Here, we report a polymeric dual-band QBIC device in THz. It exhibits an ultrahigh experimental Q factor of 427.1 above 4 THz. The device is composed of an asymmetric resonant waveguide grating structure made of low-loss styrene-butadiene-styrene polymer, obtained by a simple and precise version printing method suitable for mass production. Spectral shapes and Q factors of the two QBIC bands can be independently adjusted, demonstrating flexibility towards different potential applications. The presented strategy with the achieved device shall promote the application of THz technology in high-frequency THz bands.
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