A novel method for designing chirp characteristics in electroabsorption MQW optical modulators

We propose a novel method to control the chirp parameter characteristics in electroabsorption (EA) multiquantum-well (MQW) optical modulators. We demonstrate that a large decrease of absorption on the short wavelength side enables us to achieve a negative chirp parameter that is independent of the extinction characteristics. This is achieved by enhancing the decrease in the absorption by higher states, which can be brought about by a shallow heavy-hole band discontinuity. It is also experimentally shown that a negative chirp operation from a near-zero-bias voltage in GaInAsP MQW optical modulators is realized by applying this new concept.