OPTICAL-KERR-ENHANCED MODE-LOCKING OF A LAMP-PUMPED ND-YAG LASER

We discuss the potential use of three new mode-locking techniques, namely additive-pulse mode locking, the combination of self-phase modulation and group velocity dispersion, and Kerr lens mode locking, as simple retrofits to enhance the performance of conventional multi-watt lamp-pumped Nd:YAG lasers. Of the three, we discard the APM technique because of structural and power-handling difficulties. We then discuss theoretically and confirm experimentally that the combination of SPM plus gain dispersion can lead to pulsewidth reduction by a factor of 2 to 2.5 but not more, in agreement with the analysis of Haus and Silberberg. Finally, while KLM can be very effective as a fast saturable absorber in many types of lasers, we find that its application to lamp-pumped YAG lasers is frustrated by instabilities in thermal focusing and transverse mode position characteristic of this type of laser.