Photonic crystal based ring resonators are best choice for designing all-optical devices. In this paper, we used a basic structure of photonic crystal ring resonators and designed all optical logic gates which are working using the Kerr effect. The proposed gates consisted of upper and lower waveguides coupled through a resonator which was designed for dropping of special wavelength. The resonance wavelength was designed for 1550 nm telecom operation wavelength. We used numerical methods such as plane wave expansion and finite difference time domain (FDTD) for performing our simulations and studied the optical properties of the proposed structures. Our results showed that the critical input power for triggering the gate output was lower compared to previously reported gates.