Direct measurement of the electric-field-dependent absorption coefficient in GaAs/AlGaAs multiple quantum wells

Abstract

Although large changes in the absorption coefficient of multiple quantum wells (MQW’s) with applied voltage have been reported, no accurate measurement of the minimum absorption coefficient, which determines the absorption component of the device insertion loss, has been reported. Using a new measurement technique, we measure this minimum absorption coefficient, and determine that, for a device with a 10:1 on/off ratio and a 7 dB insertion loss, absorption contributes 2.2 dB of the insertion loss. We are able to predict absorption losses of future devices and show that, by a slight change in operating wavelength, the absorption loss can be greatly reduced.