Chemical oxygen-iodine laser power generation with an off-axis hybrid resonator

Abstract

A rectangular negative branch off-axis hybrid resonator was coupled to a 10 kW class chemical oxygen-iodine laser. Resonator setup and alignment turned out to be straightforward. The extracted power was 6.6 kW and reached approximately 70% of the power for an optimized stable resonator. The divergence of the emitted laser beam in the unstable direction was lower than two times the diffraction limit. Experimentally measured margins for mirror misalignment were found in close agreement with numerical calculations.

High beam quality COIL with hybrid resonators

“…The value is well within the expected range [9] : The outcoupling fraction determined by the resonator mirror design is chosen higher than optimum; due to the sharp edges of the outcoupling mirror, diffraction losses are enlarged compared to the stable resonator device; additionally, some hundred Watts of power are lost by a residual transmission through the glass body of the resonator mirrors. …”

Analysis of lasing in COILs with positive and negative branch unstable resonators using a simple geometrical-optics model

“…To improve the beam quality, COILs with different kinds of unstable resonators were recently tested. 1,2 High optical extraction efficiency and small beam divergence close to the diffraction limit in the flow direction were obtained. To determine the intensity and phase distribution in the far and near fields as well as the beam divergence rather complex procedure for calculating the three-dimensional mode pattern was applied by different authors.…”

Negative branch hybrid resonator for COIL

“…Hybrid resonators combine a stable and an unstable direction which can be treated separately in experiment and theory 6,7 . The size of the mirrors can be easily adapted to the dimensions of the gain medium.…”