High frequency intensity modulation of a CO2 waveguide laser by mode-locking techniques

Mode-locking techniques are well known for the generation of short pulses. However, little work has been done to evaluate the use of this technique with long wavelength (10.6 mu m) CO2 waveguide lasers. For this region of the spectrum, mode locking has the advantage of requiring smaller modulation voltage than other conventional modulation techniques which makes possible the generation of pulses at a frequency higher than 100 MHz. The efficient generation of pulses at these frequencies makes this type of laser attractive for active imaging at long wavelengths. In this paper, the design of a mode-locked waveguide CO2 laser is reported and its characteristics of operation are compared with an existing model. Significant depth of modulation is observed at 190 MHz with an applied modulation voltage lower than 50 V. From the comparison between the experimental results and the theoretical model, improvements are proposed. (C) 1996 American Institute of Physics.