Chirp dependence in InGaAs InAlAs multiple quantum well electro-absorptivemodulators near polarization-independent conditions

We study the dependence of the chirp parameter on heavy- and light-hole ene rgy splitting by analyzing the change in the absorption curve of different InGaAs/InAlAs p-i-n multiple quantum well structures designed for use in am plitude modulators. We observe, for the transverse electric mode, a high ch irp parameter for the sample whose fundamental transition involves the ligh t hole, whereas for samples whose fundamental transition involves the heavy hole, the more polarization sensitive the samples are, the smaller the chi rp parameter is. This indicates that it is not possible to have tensile str ained InGaAs/InAlAs multiple quantum well structures for electro-absorptive modulators which are simultaneously chirp-free and polarization independen t. (C) 1999 American Institute of Physics. [S0003-6951(99)01028-1].