| Because of its unique wave-guiding principle and transmission characteristics, the slot waveguide has significant application potentials in nonlinear optics, micro-nano optical sensing, functional photonic devices, etc. Firstly, we analytically solved the guided transverse magnetic modes of symmetrical planar slot waveguides and showed that there were four possible types of modes in slot waveguides including cos-, cosh-, sin- and sinh-modes. The modal field solutions, characteristic equations and cutoff conditions were provided for every type. Secondly, we numerically solved the modes in strip slot waveguides of different refractive index relations. We shown that their modal types and characteristics are similar to those of planar slot waveguides. Then the birefringence characteristics of strip slot waveguides are calculated, and the effect of the waveguide structural parameters on the effective refractive indexes of TE and TM modes is provided. We designed a polarization-independent coupler by two slot waveguides and a polarization-dependent coupler using a strip waveguide and a slot waveguide. At last, a slot waveguide ring resonator is constructed, whose resonance wavelength was 1.55 ?m and only the TE mode can be resonant in it. Work in this thesis provides the basis of modal theory, birefringence characteristics and valuable design examples for design and applications of slot waveguides and slot waveguide couplers and ring resonators. |
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