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Optical Engineering

Output beam analysis of an unstable resonator with a large Fresnel number for a chemical oxygen iodine laser
Author(s): Deli Yu; Fengting Sang; Yuqi Jin; Yi Sun
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Paper Abstract

During the operation of a laser in an unstable resonator with a large Fresnel number, as the output power of a chemical oxygen iodine laser (COIL) is increased, instability in the output laser beam will occur, behaving mainly as far-field beam spot drift and deformation. To interpret this phenomenon, a simulation of the output beam mode of this kind of laser was developed by using the method of fast Fourier transform. From the result of calculation, we propose that the presence of the nonuniform gain in the COIL produces a skewed output intensity distribution, which causes the mirror to tilt and bulge due to thermal expansion. As the output power is increased, the mirror surface, especially the back of the scraper mirror, will absorb more and more heat, causing thermal expansion of the mirror front surface to occur more seriously, thus resulting in the tilting and deformation of the far-field beam spot. The initial misalignment of the direction is also an important factor leading to far-field beam spot drift and deformation.

Paper Details

Date Published: 1 October 2002
PDF: 7 pages
Opt. Eng. 41(10) doi: 10.1117/1.1499971
Published in: Optical Engineering Volume 41, Issue 10
Show Author Affiliations
Deli Yu, Dalian Institute of Chemical Physics (Singapore)
Fengting Sang, Dalian Institute of Chemical Physics (China)
Yuqi Jin, Dalian Institute of Chemical Physics (China)
Yi Sun, Dalian Institute of Chemical Physics (China)


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