Direct comparison of InGaAs/InGaAlAs and InGaAs/InGaAsP quantum well modulators

Using picosecond pump-probe measurements, InGaAs/InGaAlAs and InGaAs/InGaAsP quantum well modulator structures are compared directly. It is found that the short-pulse exciton saturation intensity for the Al-based structure is at least 10 times that for the P-based system. The more efficient carrier sweep-out observed in the Al-based modulator is due to the lower valence-band discontinuity, making it by far the more attractive structure for high-power applications.