Tunable ultraviolet radiation by second-harmonic generation in periodically poled lithium tantalate.

We describe electric-field poling of fine-pitch ferroelectric domain gratings in lithium tantalate and characterization of nonlinear-optical properties by single-pass quasi-phase-matched second-harmonic generation (QPM SHG). With a 7.5-microm-period grating, the observed effective nonlinear coefficient for first-order QPM SHG of 532-nm radiation is 9 pm/V, whereas for a grating with a 2.625-microm period, 2.6 pm/V was observed for second-order QPM SHG of 325-nm radiation. These values are 100% and 55% of the theoretically expected values, respectively. We derive a temperature-dependent Sellmeier equation for lithium tantalate that is valid deeper into the UV than currently available results, based on temperature-tuning experiments at different QPM grating periods combined with refractive-index data in the literature.

[1]  W. Bond.  Measurement of the Refractive Indices of Several Crystals , 1965 .

[2]  N. Bloembergen,et al.  Interactions between light waves in a nonlinear dielectric , 1962 .

[3]  M. Fejer,et al.  Quasi-phase-matched second harmonic generation: tuning and tolerances , 1992 .

[4]  M. L. Bortz,et al.  Noncritical quasi-phase-matched second harmonic generation in an annealed proton-exchanged LiNbO/sub 3/ waveguide , 1994 .

[5]  Hans M. Hertz,et al.  QUASIPHASE-MATCHED SECOND HARMONIC GENERATION OF BLUE LIGHT IN ELECTRICALLY PERIODICALLY-POLED LITHIUM TANTALATE WAVEGUIDES , 1991 .

[6]  Kazuhisa Yamamoto,et al.  Generation of ultraviolet light by frequency doubling of a red laser diode in a first-order periodically poled bulk LiTaO3 , 1997 .

[7]  G. Boyd,et al.  Parametric Interaction of Focused Gaussian Light Beams , 1968 .

[8]  M. Lawrence,et al.  A temperature-dependent dispersion equation for congruently grown lithium niobate , 1984 .

[9]  M. Fejer,et al.  Quasi-phase-matched optical parametric oscillators in bulk periodically poled LiNbO 3 , 1995 .

[10]  D. Hanna,et al.  Highly efficient green-light generation by quasi-phase-matched frequency doubling of picosecond pulses from an amplified mode-locked Nd:YLF laser. , 1996, Optics letters.

[11]  R. T. Smith,et al.  Thermal Expansion of Lithium Tantalate and Lithium Niobate Single Crystals , 1969 .

[12]  Hiromasa Ito,et al.  Temperature‐dependent dispersion relation of ferroelectric lithium tantalate , 1996 .

[13]  Takashi Kondo,et al.  Absolute scale of second-order nonlinear-optical coefficients , 1997 .