The Optimal Design Of Silicon-Based Photonic Crystal Waveguides And The Study Of Their Coupling Devices

With the advent of the information explosion age, the traditional microelectronics technology using electrons as information carriers faces a large quantity of difficulty and pressure. While the silicon-based integrated optoelectronics using photons as information carriers provides the new devices, the new interconnect technologies and the new integration schemes for the microelectronics industry. It can provide cheap devices with low power consumption and high quality because it is compatible with the current microelectronics fabrication technology, which makes it the most promising candidate for the microelectronics industry and the leader to extend the Moore’s Law. In the silicon-based optoelectronics integrated circuit, the basic waveguide devices become the hot topic. Especially the silicon-based photonic crystal waveguides attract close attention and extensive research because of their compactness, low bending loss and high nonlinearity taking advantage of the slow light.In this thesis, the numerical simulation methods of the photonic crystal devices based on the basic theory of photonic crystal are introduced along with the designing and analyzing methods of the photonic crystal waveguide. The photonic crystal waveguides with zero dispersion have been designed and optimized. Based on the photonic crystal waveguides, the light coupling to the photonic crystal waveguides with zero dispersion and the slot photonic crystal waveguides have been focused, including the design of the coupling device and the analysis of their working theory. The major research achievements of this thesis are as follows:Firstly, three types of the photonic crystal waveguides with zero dispersion have been proposed, which are regular ellipse-hole photonic crystal waveguide, alternative ellipse-hole photonic crystal waveguide and broken hole photonic crystal waveguide. The dispersion curves of the three structures have been obtained by the plane wave expansion calculations. For the ellipse-hole structures, the influences of the structural parameters to the slow light properties have been analyzed, including the shape of the ellipse-hole and effective index of the slab. By optimizing the structures, the low dispersion slow light with a group index of42and a bandwidth of16nm has been obtained. The normalized delay bandwidth product is0.466. The related results are numerically confirmed by using the finite difference time domain simulation, showing an optical pulse delay of3.06ps with a low relative distortion of2.7%. For the broken hole photonic crystal waveguide, the width of the broken area and the central width of the photonic crystal waveguide have been discussed. By optimizing the structures, the low dispersion slow light with a extremely wide bandwidth of51nm has been obtained. The normalized delay bandwidth product is0.351.Secondly, a side coupling scheme using strip waveguide for the photonic crystal waveguide with zero dispersion has been proposed. By shifting parallelly the first two rows of the holes which are close to the line defect, the photonic crystal waveguide with zero dispersion has been obtained. The dispersion curves of the photonic crystal waveguide and the strip waveguide have been analyzed by using plane wave expansion method, from which the phase matching conditions for different width of the central region of the photon crystal waveguide and different width of the strip waveguide are obtained. The related results are numerically confirmed by using the finite difference time domain simulation. Under the phase matching condition, the coupling scheme can get a coupling efficiency of-3dB in a36μm long device.Thirdly, a side coupling scheme employing sub wavelength corrugated waveguide for the slot photonic crystal waveguide has been proposed. By changing the width of the slot in the slot photonic crystal waveguide, two types of modes have been obtained. The dispersion curves of the slot photonic crystal waveguide and the subwavelength corrugated waveguide have been analyzed by using plane wave expansion method, from which the phase matching conditions for different mode and different subwavelength corrugated waveguide are obtained. The width and duty cycle of the subwavelength corrugated waveguide are considered. The related results are numerically confirmed by using the finite difference time domain simulation. Under the phase matching condition, the coupling scheme can both get a coupling efficiency of-0.8dB for the regular mode and the slot mode of the slot photonic crystal waveguide with the lengths of20μm and12μm, respectively.