Abstract

Optical fiber image transmission using a barium titanate crystal for self-pumped phase conjugation is presented.¹ An input object, the letter "K," illuminated by a collimated argon-ion laser beam (514.5 nm), is focused into a multimode fiber (50 μm core and step index mode) and then phase conjugated in the crystal. The phase conjugated image retraverses the same fiber to compensate for the modal dispersion of the fiber. For a given experimental setup, an optimum image quality was obtained qualitatively at f = 75.6 mm in the range of 60 mm to 200 mm. As f increased, the restored K was gradually de graded in quality and significantly deformed in shape, particularly at f = 200 mm. As f decreased (e.g., f = 60 mm), the character K became quite noisy at f = 60 mm because of the increase in high spatial frequency components contained in the restored image, and the size of speckles on the restored background was reduced. Increasing the illuminating beam intensity also caused the restored K to be deformed and blurred as the intensity was varied from 10 mW to 400 mW. A reasonably good result was obtained for a wide range of the beam intensity (e.g., from 100 to 300 mW) at f = 75.6 mm, while increasing or decreasing the intensity from 200 mW significantly deformed the letter K, particularly at f = 150 mm. No restoration of the input K was obtained for f = 200 mm at high power (e.g., 400 mW). Both qualitative and quantitative analysis will be presented under various experimental conditions.

© 1992 Optical Society of America