ELECTRIC-FIELD THERMALLY POLED OPTICAL FIBERS FOR QUASI-PHASE-MATCHED2ND-HARMONIC GENERATION

We report on quasi-phase-matched frequency doubling to the blue in ele ctric-held poled optical fibers, An increase of a factor of similar to 10 in the conversion efficiency in comparison with the previous resul ts is obtained, Our experiments. show that the structure of the induce d nonlinear grating is not uniform, both longitudinally and transverse ly, For this reason the value of the effective nonlinear coefficient i s still far from the optimum expected from the measured value, through Maker's oscillation, for a uniformly poled fiber.