Ultra-short pulse generation with CO 2 lasers

Abstract

Although considerable progress has been made, and several methods now permit the generation of 10 pm pulses in the picosecond range, mode-locked CO 2 oscillators do not appear to have reached their full potential. Two techniques, passive and injection mode-locking, have been used to generate pulses shorter than 100 ps and of these injection mode-locking seems to be particularly well suited to CO 2 oscillators since it is less sensitive to the short gain lifetime and rapid gain risetime of multi-atmosphere discharges. To date, no attempt to use both techniques simultaneously has been reported for CO 2 although this approach has been applied successfully to Nd: YAG oscillators (Murray & Lowdermilk 1978). Injection mode-locking is clearly a valuable tool for the study of pulse broadening mechanisms as a function of the operating pressure of the slave laser and the intensity, duration and wavelength of the injected pulses. Such investigations are of fundamental importance to the further development of ultra-short pulse CO 2 oscillators and amplifiers, and may well lead to the routine generation of pulses as short as 10 ps.