This work aims to design and simulate a novel structure for an all-optical 4 × 2 encoder using a ring resonator through a new and unique technique. Encoders are widely used in encryption systems. The frequency modes and encoder design were analyzed using the plane-wave expansion (PWE) technique. The numerical analysis and simulations of the proposed design besides optimizations were performed using the finite-difference time-domain (FDTD) numerical solution approach. The adjuster rods, scattering rods, and the wavelength of the structure were optimized to design the structure in question. An ultra-compact structure with a footprint of 182 μm² was used for the proposed all-optical 4 × 2 encoder. Compared to other structures, the excellent contrast ratio of 27.78 dB was one of the significant features of the proposed structure. In this structure, the delay time and bitrate were 250 fs and 4 Tb/s, respectively. The simulations were performed at a central wavelength of 1.555 μm, indicating that it is better to use the proposed structure in the third telecommunication window. The proposed all-optical 4 × 2 encoder was also analyzed nonlinearly by applying the Kerr nonlinear optical effect besides the linear analysis. The effectiveness of the proposed all-optical 4 × 2 encoder was also optimal in the nonlinear mode with the contrast ratio of 11.96 dB, which was significant compared to similar nonlinear structures. The high-efficiency all-optical 4 × 2 encoder was designed using a photonic crystal ring resonator (PhCRR), which can be used in integrated optical circuits.