All Fiber Real-Time Laser Wavelength Measurement Method Based on Faraday Rotation Effect

An all fiber real-time laser wavelength measurement method based on Faraday rotation effect is proposed and demonstrated, for correcting the nonlinear tuning of wavelength sweep lasers. The wavelength measurement setup is mainly composed of a specially designed fiber magneto-optic device and a wavelength sensitive filter. When the linearly polarized lights with different wavelengths pass through the magneto-optic crystal, their polarization planes will be rotated at different angles. By taking use of the dispersion effect, the light wavelength can be measured by detecting the rotated angles. In our experiments, the wavelength resolution can reach 2.1 pm with a measurement range from 1520 to 1570 nm. Besides monitoring the wavelength tuning, it should be also useful in laser wavelength calibration and optical fiber sensing.