Quasi-phase matching in an optical fiber with periodic birefringence

The propagation of light in a polarization-preserving optical fiber with a periodically induced birefringence is analyzed theoretically and investigated experimentally. Regions of quasi-phase-matched four-wave mixing are predicted on the basis of an analysis of the light-amplitude fluctuations and full numerical simulations. The experimental results are in good agreement with the theoretical analysis, including the effect of external variation in the birefringence. The process, generated in an optical fiber having an induced periodic birefringence, is similar to that used for second-harmonic generation in a χ(2) waveguide and for modulational instability in optical fibers with periodically varying group-velocity dispersion.