Multi-Point Fiber-Optic Refractometer Using the Fresnel Reflections at Fiber Tips

We demonstrate a multi-point fiber refractometer using the Fresnel reflection at the fiber tip of each sensor. The refractometer is based on the coherent optical frequency division multiplexing technique; which permits to use a standard CW DFB diode laser and a low-frequency photodetector for simultaneous sensing signals detection. Signal demultiplexing in the frequency domain allows for multi-point refractive index measurement. The principle of operation and results of experiments are reported.