Miniaturized quasi-BICs based on a two-dimensional heterostructure to realize a low-threshold nanolaser
Linyong Qian, Xin Zhang, Jiahua Zhang, Zhengweiyi Yang, Yun Qiu, Kangni Wang
Abstract
Bound states in the continuum (BICs) have been demonstrated as an effective mechanism to achieve high quality (Q)-factor cavities for nanolasers. However, the development of a compact BIC laser with a low threshold has remained elusive. Here, we numerically report lasing action from symmetry-protected BICs in a two-dimensional heterostructure, which consists of compound gratings with finite cells surrounded by orthogonal distributed Bragg reflectors (DBRs). The compound grating is used to excite quasi-BIC resonance with a high Q-factor, and DBRs enable light confinement and localized electric fields to enhance light–matter interaction. The nanolaser with a threshold of 16.8 µJ/cm 2 is achieved within a footprint as small as 3.35 × 3.35 µm 2 . By changing the phase adjusting gap or asymmetry degree, it is possible to control the lasing emission. This work reveals a new, to our knowledge, path toward compact BIC lasers with a simple scheme for applications that require a small footprint and low threshold.