Dispersion And Coupling Characteristics Of Electromagnetic Waves In Two-dimensional Photonic Crystal Waveguides And Its Application

Recently, research on photonic crystal has become one of a focus all over the world. The basic characteristic of photonic crystals is its photonic band-gap. Therefore, it can provide novel mechanisms to control the flow of light, as a result, photonic crystal will possess widely application prospect in optics communication and photonic integrated circuits. A new type of fiber, known as photonic crystal fiber, has emerged in the past several years, which have resulted in some unusual properties unattainable with conventional optical fibers. Photonic crystal waveguides (PCWs), which are one of the most promising components of photonic crystals to be realized in photonic integrated circuits (PICs), may be constructed by introducing integrated a line defect into perfect PCs and the TM waves can propagate along the line defect. Thus they provide a wide application in light communication and photonic integrated circuits.The dispersion properties of photonic crystal fibers and the coupling characteristics of electromagnetic waves in two-dimensional photonic crystal waveguides and its application are investigated theoretically in the dissertation by using the plane wave method and the finite-difference time-domain method based on the self-imaging principle The theoretical research is given in the following.In chapter 1, the significance and actuality of this investigative problem, concept, characteristic and application of the photonic crystals is introduced. In addition, the concept, classifications, guiding light mechanism and dispersion characteristic of the photonic crystal fibre is also introduced in detail.In chapter 2, In order to investigate and computation the coincidence characteristics of multimode interference effect and self-imaging principle in two-dimensional triangle photonic crystal waveguides, a two-dimensional photonic crystal splitter has been proposed. The splitter has been calculated and analyzed by finite-difference time-domain method based on the multimode interference effect and the self-imaging principle. The results show the splitter each output of the reflection is smaller than 0.002, and the transmission is larger than 0.498, the physical origins of this performance is the self-imaging principle in the multi-mode region. This kind of multi-mode interference may find potential application in PC optical circuits. In chapter 3, It is engender photonic crystal waveguides in the integrity two-dimensional photonic crystals introducing line defect. It can see a multimode interference system with seven parallel photonic crystals single-mode waveguide coupling. In the multimode interference system, disperse curve of latent mode intersect and appear single-combination mode, it exist intensity coupling among single-combination mode and the distributing of lead mode happen change. The optical properties of the 4 port splitter have been demonstrated for TM polarization by FDTD and PCW methods. Results show that propagation direction of the output optical power in each output port of the device can be tuned by reducing the radii of the medium in the photonic crystals. It can give us a new way to devise the N-port splitter in photonic crystals tripe waveguide coupling with this device.In chapter 4, to research the photonic band gap and dispersion property of double-core photonic crystal fiber, the photonic band gap is calculated by the plane-wave expansion method at first, when relative aperture is larger than 0.2, it can be easy to propagate light in the air-core, with the propagation constant increasing. Second,_the dispersion property of double-core is investigated by a full-model, it can gained agility dispersion properties by adequacy adjust structure parameters of fibers. Results show that it can gaine near 480nm of super smoothness dispersion area with L=2um, d/L=0.4 and wave in 1.55um round; With the relative aperture and aperture distance accretion, zero dispersion point will move to short-wave. The results of this study provide an effective way to produce the efficient transmission optical signals and high-performance polarization fibers.In chapter 5, optional power splitter made by photonic crystal waveguides are believed to become essential components for compact photonic integrated circuits. We design a 1×4 optical power splitter made by linear-defect waveguides in photonic crystals, and analyze its properties using the finite-difference time-domain method. Results show that the transmission properties vary with wave frequency and branch geometry, and that an incident wave is divided equally into four output ports. To reduce the reflections at the three Y-branching regions in the 1×4 splitter, we can adjust the radii of the medium in the branching region, and achieve high transmission in each output waveguide.In chapter 6, the multipole method of the software package is adopted to numerical value and analyze the dispersion properties of six angle photonic crystal fiber. The simulation results show that can agility dasign the compensate dispersion with high dispersion,negative dslope and single mode transmission in short wave with change the air hole size d₀ of the first cladding and the pitchΛ. Analyzing show this PCF has broad application in compensate dispersion aspect.