Here, we propose an optical filter and an optical power splitter based on two-dimensionalphotonic crystal all circular ring resonators. These structures are made of a square lattice ofsilicon rods with the refractive index n1=3.464 surrounded by air (with refractive indexn2=1). First, we have designed the filter and by using that, we designed a power splitter. Thetransmission efficiency and Quality factor for both, an optical filter and an optical powersplitter, respectively, are more than 90% and 1000. Resonant modes of the all-circular ringresonator with their corresponding degenerated poles and the transmission spectra arecalculated using the PWE, and 2D-FDTD methods respectively. Manuscript profile