The ceramic cavity uses a ceramic body containing 99.7% aluminum oxide as a laser reflector and is processed at high temperature to form pores. Its spectral reflectance reaches over 97%. Compared with electroplating metal, it has a longer lifespan. Especially, ceramic cavities with uranium can achieve higher reflectivity, with a reflectivity of 97.8% for wavelengths around 1000NM and other wavelengths