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Proceedings Paper

Fabrication of small Bragg reflectors in glass with refractive index change induced by ultrashort laser pulses
Author(s): Kazuyoshi Itoh; Tadamasa Toma; Kazuhiro Yamada
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Paper Abstract

We succeeded in fabricating small Bragg reflectors in glass and will present this experiment. We found that the photo- induced refractive index change caused by 1-mJ 130-fs laser pulses is elongated along the optical axis compared with the original intensity distribution near the focus of the fabrication beam. The length and radius of the index change were approximately 30 and 2 micrometers, respectively. We consider that the self-focusing due to the self-phase modulation resulted in this form. This structure is suited for the fabrication of small Bragg reflectors in glass. We fabricated 1 mm X 1 mm X 30 mm Bragg reflectors. By analyzing the diffraction efficiencies of higher order diffraction beams we estimated the refractive index distribution. The thickness and spacing of the periodic laminar structure were 1.5 and was 3.8 micrometers, respectively. The maximum index change was 0.0015. We note that we observed a quite large amount of scattering loss (approximately 15%) in the grating. We fabricated also a 1 mm X 1 mm X 60 mm grating by writing two layers of gratings and obtained a diffraction efficiency of 13%. Recent experimental results of photorefractive waveguides will also be reviewed.

Paper Details

Date Published: 20 September 1999
PDF: 11 pages
Proc. SPIE 3801, Photorefractive Fiber and Crystal Devices: Materials, Optical Properties, and Applications V, (20 September 1999); doi: 10.1117/12.363928
Show Author Affiliations
Kazuyoshi Itoh, Osaka Univ. (Japan)
Tadamasa Toma, Osaka Univ. (Japan)
Kazuhiro Yamada, Osaka Univ. (Japan)

Published in SPIE Proceedings Vol. 3801:
Photorefractive Fiber and Crystal Devices: Materials, Optical Properties, and Applications V
Francis T. S. Yu; Shizhuo Yin, Editor(s)

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