Digital Control of a White Light Interrogation System for Optical Fiber Interferometers

A system to interrogate optical fiber interferometric sensors with digital control is presented. The system is based on a receiving white light Mach-Zehnder interferometer and is capable of operating with four distinct synthetic and pseudo-heterodyne signal detection schemes. A differential phase detection scheme was implemented and system performance with the different processing schemes was compared using fiber Bragg grating based Fabry-Pérot cavity strain sensors. With a lock-in time constant of 1 s, most digital techniques were able to nearly match the performance of a standard hardware system, demonstrating the feasibility of low-cost high-resolution interferometric systems operated with virtual instrumentation.