Rayleigh speckle-based wavemeter with high dynamic range and fast reference speckle establishment process assisted by optical frequency combs.

Compact speckle-based spectrometers that acquire lightwave wavelength from the speckle generated by turbid media are promising for high-resolution spectral analysis. For these devices, the reference establishment process is time consuming, and it is very difficult to obtain reference speckles covering a wide bandwidth with high resolution, which restricts the dynamic range in frequency (the ratio of bandwidth to resolution). In this Letter, we introduce optical frequency combs (OFCs) to the system to overcome these problems, which exist in the wavemeter based on Rayleigh speckle obtained from a single-mode fiber. In the experiment, the proposed wavemeter has a 1.5 nm bandwidth with 60 am resolution, covering a dynamic range in the frequency of 2×107, and a fast reference speckle establishment process that takes only 0.9 ms. The proposed method assisted by OFCs is a good prospect for a more practical speckle-based wavemeter with higher dynamic ranges.