Time-resolved investigations of field screening in InGaAs/InGaAlAs and InGaAs/InGaAsP multiple quantum well devices

Integrated high-speed intensity modulators based on the quantum confined Stark effect (QCSE) are highly attractive devices for optical communication systems. The authors investigated two different important well/barrier material combinations suitable for long-wavelength modulators, namely, InGaAs/InGaAsP and InGaAs/InGaAlAs. They show that the difference in the band discontinuities between the two material systems has a large influence on modulator performance. In the case of InGaAsP barriers, however, the authors did not observe such long field recovery times. It is concluded that InGaAs/InGaAsP quantum wells are more suitable for the QCSE modulator than are InGaAs/InGaAlAs devices.