Research On Athermalization And Dispersion Engineering Of Integrated Optical Waveguides

The integrated optical waveguide is an important device in integrated optics,and its optical properties determine the device function and system performance.The ther-mal effect makes the resonance peak of the microring resonator drift and seriously af-fects the device performance.The dispersion property of optical waveguides plays an important role in nonlinear effects and ultrashort laser pulse propagation in optical waveguides.Therefore,designing optical waveguides with strong temperature stability and dispersion engineering is a significant research field and important in many appli-cations.Therefore,this thesis mainly researches and designs broadband athermal optical waveguides and dispersion engineering technology.The novelties and main works of this thesis are as follows:In order to improve the temperature stability of optical waveguides,broadband athermal waveguides with low dispersion are designed.Firstly,three different optical waveguides,namely triple-layer,bilayer and strip-shaped optical waveguides,are pro-posed,with effective thermo-optic coefficients in the range of±1×10^-6/K,bandwidths greater than 700 nm,and low dispersion;Secondly,we propose a LiNbO₃ waveguide to enable broadband athermal property based on“mode balancing”technique,with a small effective TOC within±5×10^-7/K,over a 1020 nm bandwidth,from 1300 to 2320nm.Meanwhile,this waveguide exhibits a flat and low dispersion of±17 ps/nm/km from 1460 to 2040 nm,which is suitable for wideband nonlinear parametric interactions with phase matching.Optical and electrical fields have a good overlap,which enables a low V_π·L of 3.2 V·cm and low metal-induced absorption loss of 0.03 dB/cm and the effective TOC is 4.5×10^-7/K at 1550-nm wavelength,which are essential to a LiNbO₃modulator with high performance.In dispersion engineering technology,firstly,using chalcogenide glass Ge Sb Se and Ge Sb S as the main materials,mid-infrared optical waveguides with different struc-tures were designed and their dispersion characteristics and transmission mode charac-teristics in the mid-infrared band are studied for single-mode operation.A WG4-type optical waveguide structure is designed,which can ensure single-mode characteristics and flat dispersion in the wavelength range of 1.9～9μm.For flat dispersion and multi-ple zero dispersion wavelengths,a WG6-type waveguide is designed,which not only has a simple structure,but also has a flat dispersion profile and five zero dispersion wavelengths over a 12.9-μm bandwidth.Secondly,a bilayer optical waveguide is pro-posed,and its TE mode has a flat saddle-shaped mixed dispersion profile.The wave-guide is applied in supercontinuum generation.The supercontinuum shows low than3dB power fluctuation over 500 nm bandwidth.Finally,a vertical slot optical wave-guide with Al₂O₃ and TiO₂ is designed.This waveguide is applied in nonlinear effects and used as ultrashort laser pulse compressor.