| Co-Investigator(Kenkyū-buntansha) |
ASAKAWA Kiyoshi The Femtosecond Technology Research Association, Senior Researcher, 主任研究員
KAWAMATA Jun Hokkaido University, Research Institute for Electronic Science, Assistant, 電子科学研究所, 助手 (40214689)
IWAI Toshiaki Hokkaido University, Research Institute for Electronic Science, Associate Professor, 電子科学研究所, 助教授 (80183193)
YAMANAKA Akio Hokkaido University, Research Institute for Electronic Science, Assistant, 電子科学研究所, 助手 (30182570)
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| Research Abstract |
1. Development of photonic crystals (PCs) : We successfully developed 1) two-dimensional (2D) air-rods type PCs, 2) 2D slab (quasi- 3D) type of PCs, and 3) three- dimensional (2D) PC of ordered spheres, and revealed their optical properties. Those were fabricated in this order by using the capillary method for arrayed fibers, the state-of- arts micro-machining technique for the dielectric waveguide with AlGaAs core-layer, and radiation pressure and self-organization of polystyrene particles, respectively. As a result, we find that the PC of 1) is the first one developed with a band gap at near-infrared wavelengths. Ass for 2), we have for the first time identified the guided modes and verified the existence of the band gap for PC slabs. We also fabricated PCs with line defect and identified experimentally the defect or local modes.
2. Interaction between light and PC : 1) Using time-of-flight of sub-picosecond light pulse we find that the group-velocity vg is smaller as the band edge is
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approached, and have observed a vg-value as small as 0.05 times c (light velocity in vacuum). 2) We observed for the first time laser action in a 2D PC. This phenomenon is interpreted as arising from a small vg, which makes the effective interaction length between light and matter long enough. 3) We experimentally demonstrated that the so-called phase- matching is easily satisfied at various wavelengths in a PC, either due to its unique band dispersion, or with help of Umclapp process. 4) We have revealed, by developing newly a powerful spectrometer, that PC-slab-based waveguides with a line of air-holes missing show distinguished optical properties. Namely, we identified unambiguously the defect or local modes for a variety of components designed and fabricated, such as abruptly-bent ones, Y-splitter, and directional coupler, and also measured propagation loss of those. As a result, we have provided a firm basis for developing ultra-fast, planar light integrated circuit for future telecommunication use. Less
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