JaLCDOI 10.18926/15458
FullText URL Mem_Fac_Eng_OU_28_2_33.pdf
Author Wang, Ming| Ahmed, Anis| Wada, Osami| Koga, Ryuji|
Abstract Proposed here is a convenient optical system to collimate the crescent shaped blue laser beam radiated from a Cerenkov SHG in channel waveguide configuration. This collimation system is consisted of a parabolic mirror and has a very large tolerance to the mirror displacement. The anisotropy of the nonlinear crystal on which the waveguide is fabricated has been taken into account. The optimum mirror location is given to obtain a collimated blue laser beam with an aberration less than 0.07λ. By using an objective lens, the collimated beam can be focused down to a thin beam with the spot size less than 1μm.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1994-03-15
Volume volume28
Issue issue2
Start Page 33
End Page 44
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307149
JaLCDOI 10.18926/15419
FullText URL Mem_Fac_Eng_OU_29_2_49.pdf
Author Ahmed, Anis| Taniguchi, Shinji| Wada, Osami| Wang, Ming| Koga, Ryuji|
Abstract For weakly guiding dielectric waveguides, the eigenmode field distributions are calculated numerically with a simple algorithm. In this numerical method, the transverse sampling space can be chosen arbitrarily, and hence a narrow waveguide can be analyzed. The field satisfying scalar wave equation is expressed by the discrete Fourier transform and the mode eigenvalues and eigenfunctions are calculated by solving an eigenvalue equation numerically. The validity of this method is checked for 2-D waveguides having step and parabolic or square index distributions. It is found that for the well guided TE modes of the slab waveguide, the accuracy of this method is remarkably good, but some discrepancies are found if the mode is near cut off. In the problems where the normalized guide index b is small, caution should be taken in applying the results of this numerical method.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-03-27
Volume volume29
Issue issue2
Start Page 49
End Page 55
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307858
JaLCDOI 10.18926/15384
FullText URL Mem_Fac_Eng_OU_30_1_99.pdf
Author Wang, Ming| Wada, Osami| Koga, Ryuji|
Abstract A cylindric mirror was used, in place of a parabolic mirror, to collimate the crescent blue laser beam radiated from the Cerenkov SHG in channel waveguide configuration. The cylindric mirror radius is requested to be twice the focal length of the parabolic mirror. The focusing effect of the cylindric mirror in collimation can be compensated by slightly lifting the mirror in its normal direction. Under the condition that the mirror was declined by 5.56° and lifted by 25 μm, we got the collimated beam with divergence angle less than 1.3 mrad. In the focusing experiment, the collimated beam was focused with spotsize of 1.8 μm. The details on the analysis and experiment are reported.
Publication Title Memoirs of the Faculty of Engineering, Okayama University
Published Date 1995-12-28
Volume volume30
Issue issue1
Start Page 99
End Page 110
ISSN 0475-0071
language 英語
File Version publisher
NAID 120002307418