All-optical polarization-encoded negabinary signed-digit adder designs using terahertz-optical-asymmetric-demultiplexer switches

In contrast to intensity-encoded negabinary modified signed-digit number representation, a polarization-encoding scheme is proposed to design all-optical adders. The utilization of the proposed polarization-encoding produces more efficient circuits in terms of gates numbers and circuit delays. Three all-optical adder circuits are designed using Terahertz-Optical-Asymmetric-Demultiplexer (TOAD) switches, polarization beam splitters, polarization converters, and beam combiners. It will be shown that the proposed circuits utilize 51.7%, 45.5%, and 21% less gates and they are faster by 44.4%, 42.9%, and 40%, respectively, than the corresponding intensity-encoded circuits.