Design of a Reflective Type Optical Fiber Sensor Based on Multiple Total-Internal Reflections Theory in Heterodyne Interferometry

In this paper, a reflective type optical fiber sensor (OFS) based on multiple total internal reflections in heterodyne interferometry is proposed. The sensor is made of a multimode optical fiber which cladding was removed and polished as a top shape. And the end surface of the sensor is designed as a micro-mirror. As a heterodyne optical source is launched into the optical fiber sensor at a suitable incident angle, we can obtain the phase difference between s-and p-polarizations at the output of the optical fiber sensor. By numerical simulation, it is clear that the resolution of the system by using the intensity method can reach refractive index unit (RIU) at least in the measurement range of. The OFS could be valuable for chemical, biological and biochemical sensing. It has some merits, such as, high resolution and stability, small size and real-time measurement.