Grating structures are designed at the inner wall of the Fabry-Perot (FP) resonator to enhance the performance of an FP optical filter. The rectangular grating or triangular grating (TG) structures allows the light to be propagated effectively through the FP resonator. Attributed to the grating structures, the spectrum intensity of a FP resonator with grating structures is calculated to be 4.5-fold higher than that of a FP resonator with slot. In addition, the Q-factor of the resonant peak for a FP resonator with hybrid TG structure and two slots is 9.5-fold and 4.7-fold higher than that of a FP resonator with one slot and TG configurations, respectively.