Browsing by Author "Yeh, P"

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Effect of grating detuning on volume holographic memory using photopolymer storage media: Reflection holograms
(2000)
Hsieh, ML
;
Hsu, KY
;
Yeh, P
;
光電工程學系
;
Department of Photonics
We present a study of the grating detuning effect on the volume holographic data storage using photopolymer recording material. By using the Bragg matching condition, the angle shift and the decay of the diffraction efficiency of the reconstructed beam is obtained. Then the distortion of the readout page is described. And a method for pre-compensation of the incident angles of the reading beam is presented.
Experimental observation of the slowdown of optical beams by a volume-index grating in a photorefractive LiNbO3 crystal
(2000-11-01)
Lin, SH
;
Hsu, KY
;
Yeh, P
;
電子物理學系
;
光電工程學系
We investigate the group velocity of light in a one-dimensional volume-index grating inside a photorefractive LiNbO3 crystal. The slowdown of the group electromagnetic propagation is observed experimentally by tuning of the wave number of the optical beam close to the outside edge of the forbidden bandgap. We obtain a large group index of up to 7.5 in a 3.5-cm crystal sample. The group index is compared with the result of a theoretical derivation. The results are presented and discussed. (C) 2000 Optical Society of America OCIS codes: 050.7330, 260.2030, 190.5530, 160.3730.
Pev cosmic neutrinos from the mountains
(2004-05-30)
Yeh, P
;
Athar, H
;
La Barbera, N
;
Bouaissi, S
;
Catalano, O
The NuTel collaboration is building a wide field-of-view Cerenkov telescope to be installed on a mountain site for observing near horizontal air showers emerging from another mountain. Cosmic tau neutrinos is the primary source of such showers. This technique will be realized for the first time in the v, energy range of 2 PeV to 1000 PeV. The telescope has enough sensitivity to observe cosmic neutrinos from sources like Active Galactic Nuclei and Galactic Center assuming fluxes from current theoretical models.
Theory of mode coupling in a photorefractive crystal waveguide
(2000-07-01)
Jan, HT
;
Chi, S
;
Yeh, P
;
光電工程學系
;
Department of Photonics
The mode coupling among guided modes in a photorefractive crystal waveguide is investigated. coupled equations of guided modes in a photorefractive crystal waveguide. Analytical solutions of the couples equations are obtained for a two-mode photorefractive crystal waveguide. We also numerically analyze the coupled equations of guided modes in a multimode photorefractive crystal fiber. As a result of the coupling, power may flow to the fundamental mode or the highest-order mode, depending on the direction of the crystal optical axis. In addition, we report an analytical solution of the modal power in core and cladding for all guided HEvm, and EHvm modes for cylindrical fibers made of uniaxial crystals. (C) 2000 Optical Society of America [S0740-3224(00)02406-1].