All-fiber laser wavelength measurement system based on two quadrature Faraday rotation devices

The laser wavelength measurement and tracing in real time is very important in the optical fiber sensing field. The current wavelength measurement methods are mainly based on the interference technique, such as Michelson wavemeters, which are expensive, heavy and slow. In this manuscript, we reported a all-fiber, totally passive, wavelength measurement system base on Faraday rotation devices. This laser wavelength measurement method is composed of specially designed fiber magneto-optic devices and balanced detectors. When the linearly polarized lights with different wavelengths pass through the magneto-optic crystal, their polarization planes will be rotated at different angles, then the light wavelength can be measured by detecting the rotated angles. We also discussed the accuracy improvement solution based on quadrature detection technique.