Frequency division multiplexing of optical fiber sensors using an optical delay loop with a frequency shifter

We propose a new approach for multiplexing a fiber sensor array. The proposed optical systems are interferometers using a low coherent light source. Each input signal imprinted on each sensor can be multiplexed/demultiplexed by using a series of heterodyne carriers with different intermediate frequencies. Intensity or phase modulation has been applied to the sensors in the experimental system, successfully demonstrating the function of our proposed approach. Furthermore, the condition for the proposed system to achieve optimal signal-to-noise ratio is discussed.