Design of all-optical photonic crystal half adder with T-shaped waveguides using path difference based interference

We propose a concept of designing photonic crystal based all-optical half adder using two T-shaped waveguides without Kerr-type nonlinear materials. One of them acts as an AND gate and the other one controls the AND gate output to produce sum and carry using phase controlled input. Path difference based interference pattern determines the type of the output logic produced at ports SUM and CARRY. The response time of the proposed half adder is 0.48ps with a minimum ON to OFF contrast ratio of 5.76dB and 3.19dB for AND (carry) and XOR (sum) outputs, respectively. Furthermore, the operation of the proposed structure is constant in C-band up to 1550 nm.