Abstract

A modified photorefractive total internal reflection self-pumped phase conjugate (cat) mirror has been used to feedback the residual pump beam to a TiAl2O3 laser as an additional pump. By using a prism, the cat mirror reflected all lines from an argon laser with a total reflectivity of 15%. This feedback reduced the laser threshold from 2.4 to 2.23 W while the feedback of an ordinary flat mirror with 15% reflectivity could only slightly reduce the threshold to 2.36 W. The effectiveness of the feedback pump depends on the beam quality and its coincidence with the first pump. After passing through the laser rod, the residual pump is distorted due to effects such as thermal distortion and diffraction. This distortion is sufficient to seriously degrade the effectiveness of a flat mirror feedback. The phase conjugate reflection, by its nature, is capable of correcting this distortion and automatically traces back to where it came from so that both the pumps could overlap optimally.

© 1989 Optical Society of America