Pulse Broadening in Injection Mode Locked Tea Co 2 Lasers

Injection mode locking of large-aperture TEA CO 2 lasers makes it possible to generate nanosecond pulses with high intensities [ 1 3 ] . It was shown by Dyer and Perera [6] that by injection mode locking the width of the amplified pulse depends on many variables, such as the width of the injected pulse from the master oscillator and the gas pressure of the slave oscillator. They studied the broadening of a gaussian pulse, for various gas pressures of the slave oscillator. In this paper we show both theoretically and experimentally how the width of the output pulse from the slave oscillator will depend on the width of the gaussian pulses in the injected pulse train, keeping the gas pressure as well as the other parameters constant. The experimental configuration is schematically shown in fig. 1. The pulse train coming from a small AM mode locked TEA CO 2 laser has been injected into a 5 × 5 × 60 cm 3 slave oscillator, having a very uniform discharge [8], through a small hole (~ = 1 ram) in the center o f the back-reflecting mirror of the unstable resonator. The input energy of the slave oscillator was about 100 J/liter in a 1 : 1 : 3 = CO 2 : N 2 : He mixture