Abstract

The antiresonant Fabry–Perot saturable semiconductor absorber (A-FPSA) has been used successfully as a nonlinear mirror to passively mode lock many different solid-state lasers with picosecond pulses from Nd:YLF and Nd:YAG lasers,^1,2,3 and pulses as short as 90 fs from Ndrglass lasers.^4,5 The A-FPSA is a low-temperature (LT) grown InGaAs/AlGaAs superlattice between two high-reflecting Bragg mirrors forming a high-finesse Fabry-Perot operated at antiresonance. The main advantages of the bitemporal A-FPSA are that the operation parameters, such as saturation intensity, insertion losses, and impulse response can be custom designed and adapted to the requirements of solid-state lasers, which always leads to self-starting and stable mode-locked operation. Typical drawbacks of semiconductor saturable absorbers—such as high insertion losses, low saturation intensity, and low damage threshold—are circumvented. We present detailed experimental investigations of the saturation behaviour of A-FPSAs and derive quantitative design rules, which allow for further optimization and adaptation of the device to other laser systems.

© 1994 IEEE