Q-switching and quasi-phase-matching using a domain structured LiNbO3 crystal.

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).

Switchable phase/intensity sensor made with ring-shaped and hexagonal ferroelectric domains.

We present a device, similar to a Shack-Hartmann sensor, that can detect both the intensity distribution and wavefront of an incident wave. Its operation is based on the use of an array of electrically controllable Fresnel zone plates made in a ferroelectric crystal, lithium niobate. This sensor, which requires only one camera, can be quickly switched between intensity- and phase-detecting modes. Two kinds of arrays are shown: Fresnel zone plates with a few ring-shaped ferroelectric domains and plates made with nested hexagonal domains. Both arrays are suitable for use in a Shack-Hartmann wavefront sensor. However, since in lithium niobate domains naturally tend to form hexagons, it is easier to make hexagonal, rather than ring-shaped, domains and, consequently, smaller zone plates can be produced. This allows an increase in the number of zone plates and a reduction in their focal length, which improves the fidelity of the reconstructed wavefront.

Electro-optic vortex-producing lenses using spiral-shaped ferroelectric domains.

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).

RGB source based on simultaneous quasi-phasematched second and third harmonic generation in periodically poled lithium niobate.

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.