In Reflection Metal-Coated Diaphragm Microphone Using PCF Modal Interferometer

Starting from non-destructive testing to underwater surveillance, acoustic sensors are finding a variety of modern-day applications. In this article, we propose a double/hybrid interferometry optical microphone. We have combined the intermodal interference of SMF-SCPCF section with extrinsic Fabry-Perot interferometer to construct a highly sensitive, compact and robust optical microphone. The sensor head consists of an SMF-SCPCF spliced section placed in front of an aluminium coated nitrile diaphragm. The acoustic sensitivity and noise-limited minimum detectable pressure (MDP) of the proposed microphone is 34.8 nm/kPa and 0.26 P/root Hz at 1400 Hz. We also recorded the angular response of the proposed optical microphone and the final directionality pattern is of 'cardioid' type which makes it a preferable option for a wide variety of applications.

Automated summary

This article presents a highly sensitive and robust optical microphone utilizing interferometry technology. The microphone has an acoustic sensitivity of 34.8 nm/kPa and a noise-limited minimum detectable pressure of 0.26 P/root Hz, making it suitable for a wide range of applications. The directional pattern of the microphone is 'cardioid', further enhancing its versatility.