Whispering-gallery mode hexagonal micro/nano-cavity lasersPhotonics Research
- Yue-De Yang, Min Tang, Fu-Li Wang, Zhi-Xiong Xiao, Jin-Long Xiao, and Yong-Zhen Huang
- received 01/31/2019; accepted 03/14/2019; posted 03/14/2019; Doc. ID 359279
- Abstract: Whispering-gallery mode (WGM) hexagonal optical micro/nano-cavities can be utilized as high quality (Q) resonators for realizing compact-size low-threshold lasers. In this paper, we review the progress in WGM hexagonal micro/nano-cavity lasers comprehensively. The high-Q WGMs in hexagonal cavities are divided into two kinds of resonances propagating along the hexagonal and triangular periodic orbits with distinct mode characteristics according to the theoretical analyses and numerical simulations, while the WGMs in wavelength-scale nanocavity cannot be well described by the ray model. The hexagonal micro/nano-cavity lasers can be made by both bottom-up and top-down processes leading to the diversity of these lasers. The ZnO- or nitride-based semiconductor material generally has a wurtzite crystal structure and typically presents a natural hexagonal cross section. The bottom-up growth guarantees smooth surface faceting and hence reduces the scattering loss effectively. Laser emissions have been successfully demonstrated in the synthesized hexagonal micro/nano-cavities with various materials and structures. Furthermore, slight deformation can be easily introduced and precisely controlled in the top-down fabrication, which allows the manipulation of lasing modes. WGM lasing with excellent single-transverse-mode property was realized in waveguide-coupled ideal and deformed hexagonal microcavity lasers.