Low-threshold InGaN-based whispering gallery mode laser with lateral nanoporous distributed Bragg reflector

Whispering gallery mode (WGM) lasers have been regarded as an ideal light source for photonic integration, where low threshold lasing is essential for energy efficient optical communication. Here, we demonstrate a novel InGaN-based WGM microdisk laser with the optical-resonant lateral nanoporous distributed Bragg reflector (DBR). The continuous wave WGM lasing has been achieved at room temperature with ultra-low threshold down to 5.8 kW/cm², which is more than one order of magnitude lower than previous record with similar diameter. Combined with the finite differential time domain simulations, we found that the lateral nanoporous GaN-based DBR can effectively confine the light field, which significantly enhanced the optical confinement factor and thus reduced the lasing threshold. Our work demonstrates the importance of the adoption of optical resonant structures to improve the optoelectronic device performance and will stimulate the development of the on-chip low energy-consumption lighting for photonic integrated circuits.