Single-mode frequency-agile 9-11 mu m CO2 laser local oscillator

A CW CO2 laser capable of being switched at a 30-Hz rate to different laser lines in the 9-11 mu m spectral region has been developed as a single mode local oscillator for high-detection-sensitivity coherent lidar applications. Over sixty (CO2)-C-12-O-16 laser lines (fifty lines for a (CO2)-C-13-O-16 laser) with output power varying from 0.5 W to 5 W were obtained using a compact galvanometer controlled scanning mirror/fixed grating configuration; with a specially designed galvanometer-input voltage waveform digitally controlled through a 16-bit D/A converter, the laser frequency fluctuation was found using a heterodyne technique to have settled to about 0.3 MHz peak-to-peak in 25 ms following each line switching, which is adequate for our coherent lidar atmospheric sensing applications.