Phase-matched second-harmonic generation in periodically poled optical fibers

Phase-matched second-harmonic generation is reported in periodically poled optical fibers for the first time. A periodic χ(2) was induced in optical fibers during phase-matched periodic-electric field-induced second-harmonic generation at a fundamental wavelength of 1064 nm. Further, it is shown that periodic poling can be achieved by photo excitation with radiation of 514.5 nm wavelength while applying a spatially periodic static field. In both cases, the mode interaction HEω11→HE2ω11 is quasi-phase matched at 1064 nm. Seeding is observed in fibers beyond the poled region. A photoinduced index change has been measured using electric field induced second-harmonic generation.