RESUMEN
We report a device that acts as an active Q-switch and a quasi-phase-matching structure. It is a domain-structured LiNbO3 crystal, where the Q-switching is performed by electro-optic deflection and the wavelength conversion is produced by quasi-phase-matched optical parametric generation. By introducing this device into a diode-pumped Nd:YAG laser we obtained pulses at 1064 nm (~10 ns FWHM, 195 µJ) and 1617 nm (~3 ns, 15 µJ).
RESUMEN
We present electrically controlled wavefront modulators that simultaneously focus and introduce vorticity to an incident beam. These modulators are made out of spiral-shaped 180 degrees ferroelectric domains in lithium niobate; they have a virtually instantaneous response time, withstand high power and can be used throughout the transparency region of the material (0.4 - 5 microm).
RESUMEN
We present a pulsed RGB source based on cascaded nonlinear processes that occur inside a single crystal of PPLN with two poling periodicities placed in tandem. The first periodicity produces a ~1.43 mum signal through optical parametric generation and the last section simultaneously produces the second (near - IR) and third harmonic (blue). The green is produced by second harmonic generation of the pump and the red is produced by non-phase-matched sum-frequency generation between the signal and pump beam.
RESUMEN
In certain crystals, photorefractive two-beam coupling is predicted for orthogonally polarized optical beams. The prediction follows from the phenomenological tensor form of the photogalvanic current. We demonstrate this coupling by measuring the complex beam-coupling coefficient in barium titanate and show that the photogalvanic current correctly predicts the form for the coefficient as a function of the beam crossing angle.
RESUMEN
Under certain conditions the direction of a beam diffracted from a photorefractive grating wanders as the grating decays. This phenomenon is due to competition between the original grating and those formed spontaneously by the Fabry-Perot modes produced by the crystal's surfaces.
RESUMEN
We present a method of determining the distribution of sizes of ferroelectric 180 degrees domains in BaTiO(3), using second-harmonic scattering. We find that the domains are rods with approximately square cross sections that extend from the -c to the +c face of the crystal, with widths ranging from 2 to 150 mum.
RESUMEN
We present a method to separate the effects of trap gratings and electro-optic gratings in BaTiO(3) crystals, and we determine the true spatial shift between the electro-optic grating and the optical intensity pattern. At small beam-crossing angles this spatial shift is strongly affected by a photogalvanic current in the crystal.
RESUMEN
Two optical beams can couple in a photorefractive crystal without using the electro-optic effect. Beam coupling is due to a spatially modulated absorption caused by the rearrangement of trapped charges. We use these gratings to determine the effective photorefractive trap density for several barium titanate crystals.