Superlinear enhancement of discharge driven electric oxygen-iodine laser by increasing g ₀L

Continuing experiments with electric oxygen-iodine laser (ElectricOIL) technology have significantly increased laser power output by increasing the product of gain and gain-length, g ₀L. The authors report on progress with recent ElectricOIL devices utilizing a new concentric discharge geometry with improved O ₂(a ¹Δ) production at higher discharge operating pressure at higher system flow rates. O ₂(a ¹Δ) produced in flowing radio-frequency discharge in O ₂-He-NO gas mixture is used to pump I( ²P _1/2) by near-resonant energy transfer, and laser power is extracted on the I( ²P _1/2)→ I( ²P _3/2) transition at 1315 nm. Advancements in heat exchanger design reduce O ₂(a ¹Δ) wall loss without sacrificing significant cooling efficiency improving best gain performance from 0.26 to 0.30% cm ^-1. Modeling of recent data is presented. By increasing the gain length (system size) by a factor of 3, a 5-fold increase in laser output on the 1315-nm transition of atomic iodine was achieved. Flow conditions with g ₀L=0.042 were used to extract a continuous wave average total laser power of 481 W. A low frequency ±11.9% oscillation in the total power was observed giving a peak outcoupled power of 538 W.