A metallic photonic box capable of intensifying light at a certain wavelength, includes: a metallic surrounding forming a resonance chamber; and an insulator layer, disposed in the resonance chamber, having a predetermined dimension defining a cut-off wavelength, which inhibits light of a wavelength greater than the cut-off wavelength from resonating, whereby when the metallic photonic box is heated to generate light radiation, the light radiation is intensified at a wavelength rage predetermined by the cut-off wavelength.