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.