Principles of Ultrashort Pulse Generation

Abstract

This Chapter gives an overview on various techniques employed today for ultrashort pulse generation. As an introduction to the concept of mode locking, it is briefly explained how phase locking the axial modes of a laser cavity can lead to the generation of short pulses. Both active mode locking, where an external signal modulates the radiation inside the cavity, and passive mode locking, where an intensity-dependent loss in combination with the laser radiation itself provides the necessary modulation, are explained. Since passive mode locking allows for the generation of the shortest pulses, three different experimental schemes are introduced: Passive mode locking employing an intracavity Kerr-lens (KLM), additive pulse mode locking (APM) and mode locking using a semiconductor saturable absorber.