THEORETICAL-ANALYSIS OF A BRANCH LINE QUANTUM DIRECTIONAL COUPLER

We propose a new quantum directional coupler which consists of two par allel electron waveguides coupled by branch lines. The component is ba sed on a high mobility modulation-doped heterostructure, where the cha nnel is constricted by a double H gate pattern at nanometer scale. The theoretical analysis is conducted by the solving of the two-dimension al Schrodinger equation in the channel using mode matching techniques. Transmission and reflexion spectra calculated at the four ports of th e structure show that 3 dB coupling coefficient along with a directivi ty of 17 dB can be achieved. (C) 1994 American Institute of Physics.