The research in the field of quantum electronics is gaining more momentum over the solid state physics device design. In the proposed research we have designed an ultra compact optical T flip-flop in two dimensional (2-D) photonic crystals (PhCs) on a rectangular lattice with 16 x 9 dielectric rods in air configuration. The principle mechanism used here is adding an extra input called reference input to achieve logic high for no power applied at the input of T flip-flop. The two junctions are created for guiding the light wave towards the output. The reference input and one refractive index varied dielectric rod placed near the junction to confine the output power along with T input. At the junction of the input-output we have used the constructive and destructive interference method to achieve maximum light confinement in the output. The plane wave expansion (PWE) method is used to compute the photonic band gap (PBG) and the finite difference time domain (FDTD) method is used to analyze electromagnetic (EM) wave propagation inside the waveguides. The time for input arrival at the output also significantly improved with reduction in the chip size. The response time for the proposed T flip-flop is 0.0049 ps and contrast ratio achieved is 13.60 dB with a chip area of 49.5µm2
