100 W Kinetically enhanced copper vapor laser at 10 kHz repetition-rate, high (∼1.5%) efficiency with low (∼1.6 kW/l) specific input power and performance of new resonator configurations

It is established here that kinetically enhanced copper vapor lasers (KE-CVLs) based on large-bore discharge tubes can provide high (>1.4%) efficiency at ∼9-10 kHz rep-rate with very low (<2 kW/l) specific input power. Comparative performance of various large-bore kinetically enhanced copper vapor lasers in the range 45-70 mm is presented for most suitable discharge tube. Maximum output power of ∼100 W was achieved with efficiency of about 1.55% at 10 kHz rep-rate from the 60 mm bore KE-CVL. The pulse to pulse efficiency of the KE-CVL was ∼2%, tube efficiency ∼2.1%, and laser pulse energy was about ∼10 mJ. These results show significant advancement in the laser system as an elemental high temperature CVL due to volumetric scaling and KE-effects combined with very low specific input power of ∼1.65 kW/l as compared to 8-9 kW/l normally required in other kinetically enhanced copper vapor lasers to generate ∼100 W output power. Performance of the KE-CVL with 3 new cavity configurations namely, (1) CAT-EYE resonator (2) hybrid resonator, and (3) modified diffraction coupled resonator with dot mirrors are presented for the first here. CAT-EYE resonator was demonstrated to achieve high misalignment tolerance without significant loss of power. A typical drift in power of ∼5% was observed with misalignment responsible for 40% decline in power in case of standard plane-plane cavity. Effect of resonator misalignment on amplifier output drift was also investigated using CAT-EYE resonator in oscillator-amplifier configuration. In case of using stable-unstable hybrid resonator, high magnification of M ∼ 1500 was realized resulting in extremely low divergence (∼0.08 mrad) beam with modest (∼20%) loss in average power. In case of modified DCR cavity, record power of about 48 W was achieved with beam divergence of about 0.1 mrad on using intra-cavity 2 × 2 array of 4 dot mirrors.