Phase-shifting optical fiber sensing with rectangular-pulse binary phase modulation

- It is a new method of phase-shifting optical fiber sensing. Rectangular-pulse binary phase modulation is used to generate three phase-shifting steps and no any other elements are needed.
- Phase shifts can be demodulated via an orthogonal demodulation algorithm. The process of data acquisition is not complex. Only three sampling points are needed in one modulation cycle.
- This method can realize the demodulation of multiplexed systems based on different multiplexing techniques.

We propose and demonstrate a new method of phase-shifting optical fiber sensing, wherein rectangular-pulse binary phase modulation is imposed on the laser source of an interferometric fiber optic sensor to generate three phase-shifting steps of −π/2, 0, and π/2 radians at the output, and the phase shifts that carry the vibration signals are demodulated with an orthogonal demodulation algorithm. This approach offers the advantages of high efficiency and low complexity because it is simple in design and implementation. Moreover, this method can be applied to successfully realize the demodulation of multiplexed systems based on different multiplexing techniques. The techniques are theoretically analyzed and experimentally demonstrated with recovering the sinusoid wave applied to the sensor. Also, in this paper, a simple multiplexed system is proposed and discussed.