High-speed communication has a lot of limitations because of slow electronic components. As a solution to these limitations, optical components will be used for high switching speed, low power consumption and large bandwidth, instead of electrical components. We have developed a photonic crystal T-shaped waveguide design to implement T flip-flop. Utilizing optimized parameters such as silicon rod radius and refractive index, this design has been analysed and examined. To implement this structure, the optical interference effect is utilized at a wavelength of 1550 nanometers. This design operates at the refractive index of 3.46 and silicon rod radius of 0.114, giving the best output value with an 14.78dB contrast ratio. Using Finite Difference Time Domain (FDTD) and plane wave expansion, the designed flipflop is simulated