A novel high sensitive laser diode sensor based on micro-cavity

In this paper, we have proposed and demonstrated a high sensitive half ring laser sensor with a deep etched-sensing region based on III-V semiconductor. A whispering gallery mode propagates along the deep etched boundary of the HRL by the deep etched mirror at the edge of the HRL. In addition, the lasing direction of the proposed sensors is controlled by the reflection coefficient of the deep etched mirror at the side of the micro-cavity. The proposed sensors have advantages that an enhanced Q-factor by a stimulated emission and a controllable lasing direction for simplified alignment system. Additionally, the ultra-small variation of the effective refractive index according to molecules interactions could be sensitively detected with the proposed sensors using by a long evanescent field at the deep etched sensing region.