| Co-Investigator(Kenkyū-buntansha) |
ASAKAWA Kiyoshi Femtosc.Tech.Res.Assoc., Senior Res., フェムト秒テクノロジー研究機構, 主任研究員
KAWAMATA Jun Res.Inst. for Elect.Sci., Res.Assoc., 電子科学研究所, 助手 (40214689)
SAKODA Kazuaki Res.Inst.for Elect.Sci., Assoc.Prof., 電子科学研究所, 助教授 (90250513)
KATAYAMA Yoshibumi Univ.Tsukuba, Prof., 先端学際領域研究センター, 教授 (60302387)
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| Research Abstract |
1. We have successfully fabricated three-types of two-dimensional (2D) photonic-crystal slabs or quasi-three dimensional ones from Al_xGa_<1-x> As by using the state-of-art semiconductor micro-machining technique. Then, we have charified optical responses of those samples, such as the transmittance spectrum and reflectance at specific wavelengths observed using a femtosecond light pulse. Thus, we have characterized, from the vewpoint of controlling the radiation field and light propagation, those samples with the help of the corresponding photonic band-structure calculated.
(1) Optical-waveguide slab perforated periodically down to midway the lower cladding-layer ; it is clarifed that although no guided modes exist, the samples with an air-filling factor smaller than 0.3 and the number of air-hole's row smaller than 10 should work for the above purpose.
(2) Air-bridge slab without any cladding-layer ; it is found that the guided modes exist, where the transmittance is almost 100%, and that this type of sample is superior.
(3) Slab with the lower cladding-layer oxidized for reducing the refractive index ; this type of sample is also found to be good, since the guided modes exist in a limited energy region.
2. We have experimentally demonstrated a few novel aspects of interaction between matter and light in a photonic crystal, by utilizing either a slab sample described above or a 2D capillary-type of air-rod crystal made of PbO fibers.
(1) We have developed a 2D photonio-crystal laser, which is based on a small group-velocity
(2) We have shown in the second-harmonic generation phenomenon that a phase-matching condition is easily fulfilled with use of a unique photonic band-structure, and that the signal is enhanced due to a small group-velocity.
(3) By observing propagation time of a femtosecond light pulse through a photonic crystal, we have for the first time clarified that the group-velocity becomes smaller by almost two orders of magnitude than that in vacuum.
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