Photonic Crystal Waveguide-type Devices And Their Applications In Terahertz Technology

Photonic crystal waveguides, includes two-dimensional plane photonic crystal waveguides and photonic crystal fibers, have been intensively researched by many groups. And photonic crystal waveguides show potential applications in many important areas like photonic integrated circuits, optical communications, optical sensing, and so on. The thesis mainly focused on photonic crystal waveguide devices, our work included slow light effect in photonic crystal waveguides, self-imaging phenomenon in multi-mode photonic crystal waveguides, a polarization splitter based on the combination of self-imaging and complete photonic bandgap, polymer photonic crystal terahertz waveguides and multiple elliptical-hole birefrigent terahertz waveguides. We also fabricated several kinds of polymer photonic crystal terahertz waveguides. Main works of the dissertation are list as follows:Firstly, slow light effects in two kinds of two-dimensional dielectric waveguides with single photonic interface were investigated. One is a photonic crystal waveguide based on the photonic bandgap, the structure shows good properties for slow light purpose, since the low GVD property of the dispersion curves near the inflection points in the slow light region is used. The other is based on a photonic crystal with negative effective refractive index. Slow light properties of the waveguide were investigated in details, and we also realized a kind of two-frequency open cavity with high Q-factor, which may find applications in two-frequency lasers and applifiers.Secondly, multi-mode interference and self-imaging in multi-mode photonic crystal waveguides are introduced. We preliminarily studied self-imaging phenomenon of a multi-mode photonic crystal waveguides in an anisotropic photonic crystal with comple bandgap, by which, we firstly proposed a novel polarization beam splitter on the combination of the self-imaging phenomena and the absolute bandgap of a photonic crystal. We got polarization extinction ratios of 22.9dB and 19.2dB for the two ouput ports of the splitter, respectively. Thirdly, we focused on polymer photonic crystal terahertz fibers and birefringent terahertz fibers. A kind of photonic crystal terahertz fiber with air-holes array in both the core and cladding was proposed, and birefringent properties of the fiber with elliptical-hole array in the core were also studied. We firstly proposed a novel elliptical-hole birefringent terahertz fiber with squeezed lattices, which shows ultra-high birefringence in a wide terahertz range, and the propagation loss can be effectively reduced since a dominant fraction of the terahertz power are propagating in the air-holes of the fiber structure.At last, transmission property of high-resistance silicon under laser radiation was studied, which may be used as waveguide-type opto-electronic modulation devices in terahertz frequency range. Using teflon microwires and micro-tubes, several kinds of photonic crystal terahertz waveguides were fabricated, and we also experimentally characterized one of the photonic crystal terahertz waveguides by a terahertz time-domain system and a continuous BWO (backward wave osciallator) terahertz source.