All-fiber nonreciprocal comb filter with wavelength tunability

Summary form only given. We demonstrate a nonreciprocal wavelength comb filter, in an all-fiber form, having complimentary transmission spectra for optical signals traveling in opposite directions. The device is based on a nonreciprocal modulator, and the position of the comb can be electronically tuned or modulated. It is shown that the spacing between the transmission peaks can be easily controlled from a fraction of a nanometer to essentially infinity.