Theory and experiment of high-speed cross-gain modulation in semiconductorlasers

We present theory and experiment for the high-speed modulation response of a quantum-well (QW) laser in the presence of an external microwave modulate d optical pump in the gain region. The model includes the effects of pump-i nduced stimulated recombination and cross-gain saturation. Expressions for the small-signal modulation response of the test laser under gain modulatio n are derived. We also present experimental results using a multiple-QW InG aAlAs Fabry-Perot (FP) laser at 1.552 mum as the test laser and an external pump by a 1.542 mum DFB laser. Comparison between electrical modulation an d optical cross-gain modulation (XGM) of the test laser is also presented, which shows improvement of the modulation bandwidth by optical XGM, Our dat a show a reduction of carrier lifetime with increasing optical pumping, a s hift of the test-laser threshold current, a change in the K factor, and a v ariation of the relaxation frequency with different pump powers. The experi mental results agree very well with the theoretical results.