Quasi-Phasematched Optical Frequency Conversion in Lithium Niobate Waveguides


Compact, solid-state, room temperature sources emitting coherent radiation from the ultraviolet to the mid-infrared would be useful for a wide range of applications. This dissertation describes the study of quasiphasematched optical frequency conversion in LiNbO3 waveguides, an attractive method for efficiently converting the output of commercially available near-infrared laser diodes to the blue and mid-infrared spectral regions. The primary goals associated with this dissertation are the characterization of the material fabrication processes used to make LiNbO3 waveguide quasi-phasematched optical frequency conversion devices and the development and characterization of devices generating coherent radiation over a wide spectral range.

Annealed proton exchanged LiNb03 waveguides were studied to understand how one can fabricate waveguides specifically tailored for nonlinear optical interactions. Investigations of the material processing and the optical properties resulted in the development of models to guide the fabrication of LiNbO3 waveguides. Ferroelectric domain inversion, induced by titanium diffusion, was used for quasi-phasematching. The domain inversion process was investigated in detail, allowing the fabrication of domain inversion gratings suitable for a wide range of quasi-phasematched nonlinear
optical interactions.

Several LiNbO3 waveguide frequency conversion devices were fabricated and characterized, including quasi-phasematched second harmonic generation devices producing milliwatts of blue light and quasiphasematched difference frequency generation devices producing mid-infrared radiation at wavelengths between 2.5 - 3.0 um. The first quasiphasematched optical parametric amplifiers and optical parametric
oscillators were also demonstrated. Finally, quasi-phasematched second harmonic generation devices with novel tuning characteristics were demonstrated.

The techniques described in this dissertation allow the fabrication of LiNbO3 waveguide optical frequency conversion devices that generate coherent radiation from 0.35 um to 4.0 um. These devices, in conjunction with laser diode pump sources, can be used to build compact, solid state, room temperature sources of coherent radiation that can satisfy the needs of many applications.


December, 1994