| All-optical buffer is essential in the realization of all-optical network scheme and it plays a key role in all-optical switching system. The development of all-optical network has to breakthrough the technology of all-optical buffer. Two-dimensional (2D) photonic crystal (PhC) and its slow light properties provide many advantages to the development of the technology of all-optical buffer. The slow light testbed is designed and the slow light properties of the fabricated PCW are measured. To be specific, the contents and main results in this thesis are described as follows:1. For three typical sorts of conventional 2D photonic crystals with dielectric rod's cross sections'shapes of hexagon, square and circular, a novel method for increasing improving the PBG of the photonic crystals is proposed. It achieves the design goal by increasing the length in X direction to be p times and rotating shapes with angleφ. The symmetry of the structures are decreased through changing the values of p andφp. Through the extensive simulations using planar wave expansion method, we find that improved PBG rate can reach up to 12% due to the photonic crystals of the three types of dielectric rod with triangular lattice. Especially for photonic crystals of rectangle rod with triangular lattice, the max PBG rate can reach 15.1%. This method provides us an important reference to design the PhC structure with better absouluty PBG. It is innovative, and currently there is no work about this to our knowledge.2. The characteristics of slow light in PhC line defect waveguide structure is studied with supercell algorithm of PWE. When the radius of defect rod is smaller than the one of PhC dielectric rod, the central frequency of guided mode transfers to lower frequency and its group velocity gets smaller and smaller as the increase of radius of defect rod; The guided mode changes the same as the increase of dielectric constant of dielectric rod. With this observation, a discussion is set out from the function of dielectric constant in PWE. Then the effect of position of defect rod on guided mode slow light is studied, and the guided mode with better linearity which represents that the curve of group velocity is more smooth and the GVD is smaller is obtained through shifting the defect rod up and down. To sum up, the size of defect rod and the change of dielectric constant mostly effects on the value of group velocity, while the change of the position of the defect rod optimizes the GVD of slow light.3. Through modifying the structure of the defedted cavity, we study the variation of the group velocity of the slow light in the 2D PhC CCW and get the CCW strucuter with ultro-small group velocity. Firstly we calculate the group velocity of the normal PhC CCW and find that the group velocity and coupling coefficient decrease as the distance between coupled cavities increases. The group velocity of the CCW structure is also calculated by changing cetral defect rod's radius only and we find that this can't reduce the group velocity. Then we design new CCW structure through modifying the radii of the central rod and around four rods. The slow light factor can reach 5.89×10-4 by varying the radii of other four rods when the radius of the central rod is zero. Ultra small slow light factor 3.26×10-4, which is about 1/10 of that of corresponding normal CCW, can be gotten if we modify the five rods at the same time. We also find that the variation of the slow light factor caused by the changing of the radius of the central rod is very small when the radii of the around four rods are set within a certain range. Considering the manufacture of PhC, this type of CCW structure has great application value since it reduces the demand of the precision.4. Combined with the application of slow light buffers, the corresponding computation method of CCW structure is introduced through the principle of tight binding method. The BIT length of coupled cavity waveguide and buffering capacity etc. are analyzed to obtain that the delay time and buffering capacity in CCW slow light buffering restrict each other. This means that, on the one hand, the coupling coefficient gets larger as the increase of space between cavities to reduce the group velocity; on the other hand, the guided mode bandwidth gets narrower and the BIT length gets longer to reduce the buffering capacity. The delay time of 1μs in PhC CCW of 9.78cm is implemented through calculation on different structures and it is 3 times larger than similar literatures. Buffering capacity can reach 3.3kbit. Moreover, the analytic results on CCW slow light structures shows that, when the space between cavities is smaller, the system gains smaller BIT length to increase the buffering capacity, which is of great applied values to slow light buffering; when the space between cavities is larger, the system gains larger nic crystals with a triangular lattice of air holes", J. Opt. Soc. Am. B, Vol.20, 2003,p.19221926.Olivier S, Smith C J M, Rattier M, et al., "Miniband transmission in a photonic crystal coupled-resonator optical waveguide", Opt. Lett., Vol.26, between (?) of measurement of PhC slow light, we analyze the test principle of the slow light testbed and decide to measure the change of the equivalent dielectric constant by testing the variation of the phase in PCW. Based on the analysis, we design the testbed. The W1 PCW is fabricated with focused ion beam (FIB) method. The obtained results demonstrate that the group index curve measured with the phase-delay method has the exact same trend with that in simulations. The time-delay of the pulse is also measured, and it fits for the theoretical result calculated according to the group index with the phase-delay method, witch is about 4.7ps.
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