High-power, kHz-repetition-rate, long-pulse-duration, narrow-linewidth 1319 nm Nd:YAG solid-state laser for a guide star laser system

We propose and demonstrate a new approach to scale the average output power with narrow linewidth and good beam quality simultaneously for a 1319 nm laser. A polarization and sequence pulsed beam combining technology is developed to add two lasers. Each laser is based on a quasi-continuous-wave diode-pumped Nd:YAG master-oscillator power-amplifier system. One provides output power of 81 W with s-polarization, M-2 = 1.49, and a repetition rate of 500 Hz. Another also operates at 500 Hz, but delivers power of 78 W with M-2 = 1.47 and p-polarization. After combination, a maximum average power of 156 W with beam quality of M-2 = 1.5 is achieved, corresponding to a combining efficiency of 98.1%. The combined beam has a 1 kHz repetition rate with 120 mu s pulse duration and similar to 0.3 GHz linewidth. To the best of our knowledge, this is a record-high output power for the solid-state 1.3 mu m lasers. All results indicate the technique of polarization beam in conjunction with sequence pulsed beam combining not only allows the scaling of the laser power while maintaining narrow linewidth and good beam quality, but also is an effective approach for increasing the pulse repetition rate.