Photocurrent saturation in short-period superlattice modulators

The effects of high intensity illumination on short-period superlattice modulators at room temperature are examined using photocurrent techniques. The authors; measurements indicate a zero bias saturation intensity of 6.5 kW/cm², considerably higher than in conventional quantum well structures with thick approximately 100 AA barriers, but lower for quantum wells with thin barriers. For moderate DC bias the change in photocurrent with applied voltage remains high even at high intensity. This implies that superlattices are useful as high-intensity optical modulators.