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Proceedings Paper

Transient characterization of modal dispersion in an optical fiber using 250-ps shuttered MCPII
Author(s): Paul A. Zagarino; George J. Yates; Matthew C. Thomas; Jeanne Cickay
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Paper Abstract

A gate MicroChannel-Plate Image Intensifier (MCPII) was used as an optical shutter with a 250 ps exposure time to record the transient image of the modally dispersed output of a 30 meter length of 600 micron diameter step index optical fiber. The fiber input was pulsed light from a Raman shifted, frequency-doubled, Nd:YAG laser having a wavelength of 559 nm and a width of 20 ps FWHM. The MCPII was synchronously gated on in time to the laser pulse Time Of Arrival. The laser light from the fiber was spatially resolved with a 50 mm fl Nikon camera lens and the fourier plane was imaged onto a MCPII. The output from the MCPII was then recorded with a RS-170 video camera and a PC based video digitizer. The relative timing between the input laser pulse and the shuttering of the MCPII was precisely adjusted to capture transient images at successive times. These images reveal not only meridional rays arriving in one to one correspondence of delay time versus angle (or distance in the fourier plane) but also the time and numerical aperture broadening due to the skew rays. Indeed one 250 ps snapshot reveals delayed emission at angles that exceed the critical angle in the fiber, i.e., a picture of skew rays leaving the fiber at an angle to the z-axis greater than the meridional critical angle after all the lower order meridional rays have gone. Experimental data will be presented.

Paper Details

Date Published: 28 May 1997
PDF: 8 pages
Proc. SPIE 2869, 22nd International Congress on High-Speed Photography and Photonics, (28 May 1997); doi: 10.1117/12.273346
Show Author Affiliations
Paul A. Zagarino, Sharpenit (United States)
George J. Yates, Los Alamos National Lab. (United States)
Matthew C. Thomas, Special Technologies Lab. (United States)
Jeanne Cickay, Speech Technologies Lab. (United States)

Published in SPIE Proceedings Vol. 2869:
22nd International Congress on High-Speed Photography and Photonics
Dennis L. Paisley; ALan M. Frank, Editor(s)

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