On the crosstalk of reversed- Delta beta directional coupler switches

Abstract

Coupled-mode theory applied to reversed- Delta beta parallel directional coupler switches with tapered-sections input and output waveguide predicts a residual crosstalk in the straight through (bar) state due to coupling within the tapered regions which could be as low as 10-15 dB. Complete switching to the cross state, however, can be achieved assuming ideal conditions. Means of reducing the crosstalk in the bar state using phase control are presented.