Nonlinear glass waveguide devices fabricated by femtosecond laser writing with thermal poling and waveguide modeling for silver ion exchange in glass.

摘要

Integrated optics technology has led to the development of miniaturized optical devices that can offer high functionality on a single chip. This technology has proven useful for a host of applications, including telecommunications, sensing, navigation, quantum optics and astronomy. Complex integrated optical devices, such as lasers, frequency converters, filters and demultiplexers, have been developed in a variety of substrate materials, including crystals, glasses, polymers and semiconductors. This thesis contributes to the field of glass integrated optics with two primary additions: Direct waveguide writing, using femtosecond lasers, is combined with thermal poling to demonstrate electro-optic (EO) and quasi-phase matched (QPM), second-order, nonlinear, parametric waveguide devices in bulk fused silica for the first time. In particular, a 25.6 mm long waveguide EO modulator in bulk glass is reported that has an effective EO coefficient of 0.17 pm/V, which is the highest value obtained to date for a planar, glass, waveguide device. Frequency doubling (SHG) is also demonstrated in a QPM, glass, waveguide device where the chi(2) grating is produced using a new method for the selective erasure of a uniformly poled region. A 1064 nm to 532 nm conversion efficiency of approximately 8 x 10-6%W-1cm-2 is obtained for this device, and it is predicted that values several hundred times larger should be achievable through careful device optimization. The second contribution of this thesis is a systematic modeling study of the silver ion exchange process in a single-alkali (Na) glass based on first principles. It is shown for the first time that a Fickian diffusion analysis, combined with a concentration-dependent diffusion coefficient in the absence of free parameters, is able to predict 2-D refractive index waveguide profiles that are in relatively good agreement with measured results. Low loss, large diameter, ring resonators are also fabricated by silver ion exchange in glass and fully characterized as part of this study.