Progress in research of linearly polarized single-mode lasing based on dual-sphere microcavity coupling

[ Instrument Network Instrument R & D ] Recently, the microstructured photophysics research team led by Zhang Long and Dong Hongxing, researchers at the Shanghai Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, cooperated with East China Normal University and Nanjing University of Aeronautics and Astronautics. A high-quality, stable linearly polarized single-mode laser is obtained in a spherical microcavity. Related research results were published as the current cover article in [Nanoscale, 12, 5805 (2020)].

Micro-nano structure optical microcavities have important applications in the field of micro-optoelectronic integrated devices and laser displays. At present, great progress has been made in many areas, such as ultra-sensitive sensors, beam splitters, low-threshold micro-cavity lasers, and mode-number controllable micro-cavities. Laser. As one of the important indicators for evaluating the quality of laser beams in microcavities, the polarization characteristics of lasers have not received enough attention and research. Micro-nano structure micro-cavity laser is different from traditional lasers that can add polarizers or introduce polarized seed beams. The lasing in the micro-cavity uses spontaneous radiation without polarization characteristics as "seed light", which makes the polarization of the lasing The degree is generally low. Based on the vernier effect, both the number of lasing modes can be reduced and the polarization direction can be filtered to a certain extent. It is an effective way to improve the polarization degree of lasing.

The research team used the perovskite dual-sphere microcavity for coupling, and successfully improved the polarization degree of the coupled lasing from ~ 0.2 to 0.78 through the vernier effect. When the distance between the two-ball microcavities is ～ 30 nm, the light-field interaction results in a single-mode lasing with a low threshold (4.09 μJ / cm2) and a high polarization (0.78). The pump was maintained for 55 minutes at a relative intensity of 1 (~ 7.2 x 104 pump excitation cycle). In addition, the modal distribution of single and coupled microspheres is analyzed, and the physical images of resonance before and after coupling are analyzed. Under the effect of the vernier effect, due to the reduction of the degenerate mode and the difference in the coupling efficiency between the TE and TM modes, the polarization degree of the laser is greatly improved. The related achievements are of great significance for promoting the research of the basic and application of micro-nano structure optical micro-cavity lasers.

This work was supported by the National Natural Science Foundation of China and the Shanghai Young Talent Project.