Performance of a high-efficiency 5-cm gain length supersonic chemical oxygen-iodine laser

The Air Force Phillips Laboratory has developed a small-scale supersonic chemical oxygen-iodine laser (COIL) test stand (VertiCOIL) to rapidly evaluate emerging potential technology improvements. VertiCOIL was designed to address issues relevant to military and commercial applications such as long run time, high-efficiency operation, and compact design. VertiCOIL demonstrated an overall chemical efficiency of nearly 27%, one of the highest chemical efficiencies ever achieved by a COIL. In addition, VertiCOIL was able to lase for greater than 1 h by employing a continuously cooled basic hydrogen peroxide (BHP) flowing loop. Measured resonator parameters were used with a simplified saturation model to calculate the optical extraction efficiency. The peak optical extraction efficiency predicted by the model was 0.82. The dependence of the predicted extraction efficiency on outcoupling fraction is in good agreement with experimental results. Combining the predicted extraction efficiency with the COIL heuristic equation results in good agreement between measured and predicted overall device chemical efficiency.