In this study, we endeavored to create and simulate a D‐type flip‐flop utilizing two‐dimensional photonic crystals featuring a square lattice. This flip‐flop, composed of just two intersecting waveguides, is both compact and straightforward. Constructed from 10 × 10 dielectric rods suspended in air, it boasts low output power in logic mode 0, creating a significant distinction between optical powers in modes 0 and 1, lending it a logical aspect. Optimized for operation at a communication wavelength of 1.55 µm, this flip‐flop proves suitable for optical communication systems. The third window optical fiber communication system is suitable for 1.55 μm wavelength because the fiber has the lowest loss. Our analysis involved calculating the band structure via the plane wave expansion method and determining the optical power distribution using the finite difference time domain method.