All optical wavelength converter based on directional coupler with electro-absorption and exciton effect

We propose an all-optical wavelength converter based on a directional coupler structure incorporating a multiple quantum well (MQW) p-i-n junction being reverse-biased, and describe results of device simulation as well as its fabrication process feasibility. By using the Korn-Luttinger band structure model and the two-particle effective mass exciton model, the absorption and refractive index change spectra versus carrier densities in 1.50 μm QW structures of InGaAsP/InGaAsP/InP and InGaAs/InAlAs/InP material systems have been obtained. A two-dimensional (2D) beam propagation method (BPM) calculation is made use of to predict all-optical wavelength conversion characteristics. The simulation reveals that the transfer functions from input to output lights become digital-like, and that optical power for switching depends on carrier sweep-out time and the degree of the exciton effect.