A frequency-tunable mode-locked CW Nd:Glass laser

Mode locking and frequency tuning of a CW light-focusing Nd : glass laser called the SELFOC Nd : glass laser were achieved. Using an acoustooptic modulator having a modest degree of modulation (about 3 percent), almost perfectly mode-locked pulses as short as 49 ps were obtained. Pulsewidth was measured with an intensity-correlation method using the second-harmonic generation in KDP. Most of the observed shapes of the intensity-correlation curves were in agreement with theories previously presented by several authors. When the laser was mode locked, the long-term averaged optical spectrum was observed to narrow considerably. Some experimental evidence that the CW SELFOC Nd:glass laser could be considered to have a homogeneously broadened line was also found. Frequency tuning was achieved by using a tilted etalon in a cavity. When a 50-μm-thick etalon was used, the tuning range was more than 40 A. Pulses obtained from a frequency-tuned mode-locked laser were as short as about 100 ps.