Optical directional coupler for telephony

摘要

The structure includes two layers of gallium-aluminium arsenide (1,5) and an intermediate layer (2) of gallium-arsenide. A pair (3,4) of metal electrodes is applied to the top layer to receive a respective coupling-controlling current (I1,I2). The coupling state which obtains in the coupler is determined as between bar coupling or cross-coupling so that light input on a waveguide is output, with amplification, on a second or third waveguide. The current injected through the electrodes determines the coupling state by changing the real part of refractive index (n1,n2,n3) of the respective waveguide section. The changing of the imaginary part of the respective refractive index is instrumental to vary the amplification.