Investigation of Cavity Length and Mode Spacing Effects in Dual-Mode Sensor

Utilizing the principles of intracavity absorption spectroscopy, a biomedical sensor has been developed. The unique feature is the deployment of dual-mode competition which renders characteristics of feasibility, cost, and investigation in various domains. Insight of the high sensitivity of this sensor, relative intensity noise (RIN) is being explored as one of the detection parameters. Cavity length and mode spacing effects of the sensor on average RIN have been investigated to optimize these parameters for improvement in RIN response of the sensor. It has been found that operating the sensor for increased mode spacing improves its RIN response by 24%. In this mode of operation, change in cavity length has almost negligible effect on RIN response of the sensor. This fact in the proposed sensor system can be used to detect various trace gases with minute concentration levels thereby revealing important information about specific diseases in human body.