High-resolution wavemeter using Rayleigh speckle obtained by optical time domain reflectometry

The characteristics of Rayleigh speckle generated from a single-mode fiber are related to the wavelength of the incident lightwave, which makes it possible to use Rayleigh speckle for spectrum measurement. Based on this feature, we propose, to the best of our knowledge, a novel wavemeter with high resolution realized using optical time domain reflectometry to obtain Rayleigh speckle. We show that the spectral resolution is inverse to the probe pulse width, with a spectral resolution of 6 fm corresponding to a 2 µs probe pulse. A correlation coefficient method is introduced to further increase the spectral resolution from 6 to 0.4 fm. Moreover, it is experimentally demonstrated that the system has the capability to resolve dynamic multi-wavelength signals with 25 µs time resolution. The proposed high-resolution wavemeter is a good prospect for cost effectiveness, compactness, and excellent performance of spectral resolution.