Panning gas and sulfur are filled inside shell of quartz bulb of microwave sulfur lamp. In addition, 1-8mg metal halide including calcium bromide or indium bromide is also filled to shell of quartz bulb. Comparing with former lamp, which contains sulfur only, the disclosed bulb increases spectral line of red light part so as to raise color-rendering property. The added metal halide does not generate influence on spectral lines emitted from former sulfur lamp. Moreover, the invention also lowers difficulties for exciting plasma. |