Ultrashort pulse generation with additive-pulse mode-locking in solid-state lasers

Abstract

Additive-pulse mode-locking (APM) in solid-state lasers provides an attractive and powerful approach for ultrashort-pulse generation. The APM technique uses a nonlinear external cavity that is coupled to the main laser cavity. The nonlinear external cavity may be viewed as a nonlinear Fabry-Perot, which functions as an intensity-dependent mirror for the main laser. Additive-pulse mode-locking thus resembles passive modelocking with a fast saturable absorber. However, the APM technique has the advantage that the nonlinearity or the effective cross section of the saturable absorber can be explicitly designed by adjusting the laser and external cavity parameters. Because APM can be used to achieve passive mode-locking without the need for active external modulation, it significantly reduces system cost and complexity.