Ultra‐fast and compact all‐optical half adder using 2D photonic crystals.

Using a two‐dimensional photonic crystal lattice, a compact and simple structure has been introduced in the present study to construct an all‐optical half adder. The designed structure operates under the interference effect. The phase difference has been created in different states by putting the point defects and the difference in the length of the input waveguides. To do analyses, the finite‐difference time‐domain method and the plane wave expansion have been used. The advantages of this design include the small dimensions, high possibility of construction, compatibility with the silicon‐based technology, and equality of the output power in the logic states 0 and 1. The contrast ratio calculated for the port Sum and the port Carry has been equal to 9.3 and 8.22 dB. The response time has been equal to 0.22 ps, generating the data transfer rate of 4.55 Tbps. [ABSTRACT FROM AUTHOR]