An optical parallel adder based on polarization-coded symbolic substitution
is presented. This adder eliminates the carry propagation chain associated with
binary addition, thereby performing the addition of two numbers in a single stage
regardless of the length of the two numbers.
"Carry-free optical binary adders", Proc. SPIE 1347, Optical Information Processing Systems and Architectures II, (27 December 1990); doi: 10.1117/12.23445; https://doi.org/10.1117/12.23445