Spectral measurements with superresolution based on periodic modulation of the spectrum.

We extend the approach recently applied for achieving spatial and temporal superresolution to spectral measurements with superresolution. The light passes previously through a filter with a periodic spectral response. Owing to the spectral modulation, the parts of the spectrum Fourier transform are shifted and transmitted through the passband of the Fourier transform of the spectrometer instrumental function. Thus, all the parts of the spectrum Fourier transform are recorded by the spectrometer and then restored by a special procedure. An inverse Fourier transform gives the spectrum restored with superresolution. We numerically demonstrate more than tenfold enhancement of the resolution by using a sampled fiber Bragg grating for spectral modulation.