Parasitic noise on the output of a CW YAG:Nd⁺³laser

An experimental investigation was conducted to reduce the parasitic noise appearing on the output of a 6-W CW YAG:Nd+3laser. Initially, low-frequency fluctuations as high as 30 percent and relaxation oscillation bursts exceeding 80 percent of the CW power level were present. Low-frequency modulation was reduced by the addition of an active feedback loop to control lamp current. Relaxation oscillations were determined to be influenced by laser rod cooling, pump-lamp aging, vibration, and intracavity optical interface quality. At the conclusion of the program, low-power fluctuations and relaxation oscillation excursions did not exceed 2 percent.