University PhD Dissertation Defense / Paulina S. Kuo (Monday, Oct. 15)

[Paulina Kuo]

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Department of Applied Physics
University Ph.D. Dissertation Defense

Thick-Film, Orientation-Patterned Gallium Arsenide
for Nonlinear Optical Frequency Conversion

Paulina Susan Kuo

Research Advisor: Professor Martin M. Fejer

15 October 2007
4:15 pm (refreshments at 4:00 pm)
Applied Physics, Room 200

ABSTRACT

         Optical frequency conversion using quasi-phasematched (QPM) 
nonlinear optical crystals is a powerful technique for generating coherent 
radiation in wavelength ranges where lasers are not readily available. 
Quasi-phasematched GaAs is an ideal material for generating infrared light 
for applications in spectroscopy and infrared countermeasures. 
Orientation-patterned gallium arsenide (OP-GaAs) is a type of QPM GaAs that 
has been recently developed. In OP-GaAs, periodic inversions of the 
crystallographic orientation are epitaxially grown into the material. The 
growth process involves molecular beam epitaxy, lithographic definition of 
QPM periods, and hydride vapor phase epitaxy. Significant progress has been 
made in increasing the quality of OP-GaAs material; periods as small as 30 
microns have been grown in 0.5 mm thick films and overall thicknesses of 1 
mm have been achieved. Furthermore, OP-GaAs loss measurements show 
attenuation coefficients of 0.005 cm-1, measured at 2-micron wavelength. 
This thesis discusses growth improvements in OP-GaAs and the 
characterization of these improvements.

         The improved material quality in OP-GaAs has allowed the 
demonstration of efficient nonlinear optical frequency conversion in the 
mid-infrared wavelength range. Several nonlinear optical devices were 
demonstrated in bulk OP-GaAs. Pumped near 3-micron wavelength, an extremely 
broadband infrared spectrum (spanning 4.5-11 microns) was obtained using 
optical parametric generation in OP-GaAs. I will also discuss an experiment 
exploring polarizations combinations of the interacting light waves in 
OP-GaAs. High symmetry in the nonlinear susceptibility tensor in GaAs 
together with isotropy in its refractive index allow efficient nonlinear 
optical mixing with circularly polarized or even depolarized waves. 
Efficient pumping of an OP-GaAs OPO with circularly polarized and 
depolarized light was achieved.
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