We present a detailed theoretical study on terahertz (THz) cavity plasmon polariton in graphene embedded in a Fabry-Pérot cavity under optical modulation. Based on classical electromagnetic theory. we obtain analytically the dispersion equation for cavity plasmon polariton (CPP) modes. The obtained results show the existence of two types of CPP modes in THz range. https://homehardware4ues.shop/product-category/frameless-glass-shower-door-parts/