Thermal-Optic Distortion-Free Solid Laser Technology
Final rept. 30 Nov 1970-30 Sep 1972
AMERICAN OPTICAL CORP SOUTHBRIDGE MA RESEARCH DIV
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This report summarizes the design considerations and experimental results obtained from four different disc lasers. These devices were successfully operated as amplifiers and oscillators at high average powers. The results were compared with the performance of solid rods of both circular and rectangular cross section. The thermal lensing, which limits the performance of solid rods, especially under Q-switched operation, was essentially eliminated with the disc approach. With the disc amplifier, transmission and gain values very close to those of solid rods have been measured. The single pass distortions were reduced by over one order of magnitude, which corresponds to an improvement in amplifier radiance of about two orders of magnitude for the disc laser in comparison to an equivalent solid rod. For Q-switched pulses, an average output power of 110 W was obtained with the disc amplifier operating at 5 pps. With the disc laser operating as normal mode oscillator, an average output power of 420 W was measured with an improvement in average radiance by a factor of 27 over that of an equivalent solid rod at its fracture point. The performance of disc lasers is limited by thermal-optic distortions in the coolant and by depolarization losses observed in Brewster disc lasers. The depolarization losses can be avoided with the normal incidence disc approach. To reduce the thermal-optic distortions in the coolant requires careful design of the flow channels and a coolant with a low thermal index coefficient.
- Lasers and Masers