High Power Femtosecond Diode Lasers

We present a concept for a femtosecond laser based on a passively mode-locked semiconductor diode laser and a tapered amplifier. The absorption in the monolithically integrated quantum well absorber is controlled by a reverse voltage bias. Excellent mode-locking stability was observed without any rf modulation applied to gain current or absorber voltage. To avoid fast gain saturation and strong nonlinear pulse distortions within the tapered amplifier the technique of chirped pulse amplification is applied. In contrast to common chirped pulse amplification setups the oscillator emits pre-chirped pulses and a stretcher stage can be omitted. A pulse duration of 267 fs was achieved after compression in the colliding pulse mode-locking regime. For the first time we adapted this technique to the generation of tailored chirped pulses and investigated the influence of the collision point in an asymmetric two-section oscillator. This diode laser system is suited as a ultrafast pulse source for high power bulk or fiber amplifiers and paves a road to highly integrated laser systems.