High-speed random access laser tuning

We have developed a technique for laser tuning at rates of 100 kHz or more using a pair of acousto-optic modulators. In addition to all-electronic wav elength control, the same modulators also can provide electronically variab le Q-switching, cavity length and power stabilization, chirp and linewidth control, and variable output coupling, all at rates far beyond what is poss ible with conventional mechanically tuned components. Tuning rates of 70 kH z have been demonstrated on a radio-frequency-pumped CO, laser, with random access to over 50 laser lines spanning a 17% range in wavelength and with wavelength discrimination better than 1 part in 1000. A compact tuner and Q -switch has been deployed in a 5-10-kHz pulsed lidar system. The modulators each operate at a fixed Bragg angle, with the acoustic frequency determini ng the selected wavelength. This arrangement doubles the wavelength resolut ion without introducing an undesirable frequency shift.