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Proceedings Paper

Profilometry using two-photon absorption of silicon avalanche photodiode
Author(s): Yosuke Tanaka; Takashi Kurokawa
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Paper Abstract

Though silicon photodetectors are usually insensitive to near infrared light of the wavelength longer than 1100 nm, they become sensitive to it with high intensity, producing photocurrent in proportion to the square of the intensity. This is due to two-photon absorption (TPA) process. So far, the TPA process in silicon photodetectors has mainly been applied to measuring the waveform of optical short pulses, since it can give the intensity correlation of incident light signals. In this paper, as a new application of the TPA process in photodetectors, we propose a novel profilometry based on Michelson interferometer with optical microwave as a light source and avalanche photodiode as a two-photon absorber. In contrast to the classical heterodyne profilometer that measures the optical path length difference from the phase of the modulated optical signal, the dynamic range of the TPA method is not limited by the bandwidth of a photodetector and attached electronic devices. The TPA method can realize the dynamic range of several millimeters to several ten meters with simple setup. The principle of the TPA based profilometry is experimentally demonstrated using fiber optic Michelson interferometer.

Paper Details

Date Published: 20 September 2002
PDF: 8 pages
Proc. SPIE 4919, Advanced Materials and Devices for Sensing and Imaging, (20 September 2002); doi: 10.1117/12.465748
Show Author Affiliations
Yosuke Tanaka, Tokyo Univ. of Agriculture and Technology (Japan)
Takashi Kurokawa, Tokyo Univ. of Agriculture and Technology (Japan)

Published in SPIE Proceedings Vol. 4919:
Advanced Materials and Devices for Sensing and Imaging
Jianquan Yao; Yukihiro Ishii, Editor(s)

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