Intensity Demodulation of Optical Vernier Effect: An Intelligent Algorithm Approach

In this article, we introduce an intensity demodulation method for the optical Vernier effect based on an intelligent algorithm. To reduce the requirement for a large number of pre-collected raw spectra for the training of the three-layer neural network, a spectrum interpolation scheme was incorporated. With the proposed method, the measurand can be demodulated by simply measuring the relative intensity at three wavelengths. A Vernier-effect temperature sensor consisting of two parallel fiber Fabry–Perot interferometers (FPIs) was fabricated and used to validate the proposed method. The experimental results demonstrate that the intensity demodulation method yields results in very good agreement with those of conventional spectral demodulation method. The sensor exhibits a sensitivity of 5.82 nm/°C and a relative error within ±1.23% in the range of 28 °C–44 °C. The proposed method enables the demodulation system to eliminate the dependence on the expensive optical spectrum analyzer (OSA). This has significant implications for reducing the cost of the optical Vernier-effect demodulation system and facilitating the practical application of such sensors.