Carrier lifetime and modulation bandwidth of a quantum well AlGaAs∕InGaP∕GaAs∕InGaAs transistor laser

A quantum well (160A) transistor laser with a 400μm cavity length that achieves the large 3dB modulation bandwidth of 13.5GHz is described. The fast base recombination (transport determined, τBL 1∕2), resulting in a resonant peak magnitude of unity and consequently a resonance frequency of ∼0GHz (no peak) in the small-signal response. Quantum well band filling and bandwidth saturation are observed on the ground state (λ=1000nm), and increase with operation on the first excited state (λ=980nm).