Periodical spectral peaking on optical pulses

Abstract

Using nonlinear optical effects, we can control the optical spectra in various ways. Here, we discovered a novel phenomenon in ultrafast nonlinear fiber optics, namely, periodical spectral peaking. A narrow spectral dip on a pulse turns into a sharp, intense peak through a nonlinear effect. This phenomenon shows periodical evolution behavior in the soliton regime. If we use absorption spectra with constant frequency separation, like molecular gas absorption spectra, we can generate almost uniform frequency spanning sharp spectra with a linewidth on the order of a few picometers and sub-THz frequency separation. The generated spectral peak almost replicates the characteristics of the absorption spectra. Fundamental characteristics and physical mechanisms were investigated both numerically and experimentally. This phenomenon provides us with a novel approach to control the optical spectra and opens up new aspects and applications of nonlinear fiber optics.