Linearization of a multiple quantum well electro-absorption modulator by using quantum well intermixing

Abstract

In this paper, we propose a new technique to suppress the nonlinearity of multiple-quantum-well (MQW) electro-absorption (EA) modulator. The nonlinearity is mainly due to the exponential-like transmission characteristics of the EA modulator and to the nonlinearity of quantum confined stark effect (QCSE). Our new technique suppresses the nonlinearity by intermixing the MQW absorption region. The optical properties such as the transition energy and the gain (or absorption) spectrum and their dependences on the bias voltages applied to the intermixed InGaAs/InGaAsP MQW absorption region have been calculated by solving the Luttinger-Kohn Hamiltonian. We show that the transfer function of a MQW-EA modulator can be tailored by introducing differently intermixed regions along the waveguide direction. We also show that the proposed technique can suppress the IMD2 (2(nd)-order intermodulation distortion) by 39.6 dB and can enhance spurious-free dynamic range (SFDR.) by 3.6 dB by choosing a proper combination of interdiffusion lengths and waveguide lengths.