Working principle, advantages and disadvantages of ultraviolet (UV) discharge lamp, UV LED and UV laser are introduced. UV modulated light is developed using UV LED as the original light, can produce standard UV modulation signal with different modulation rates and different duty ratios. In order to solve traceability of optical power, the modulated light is outputted by optical fiber. The experimental results show that the modulated light meets the requirements of UV communication receiver sensitivity test, whose optical fiber output coupling efficiency of UV source modulation is about 8%, and the maximum modulation rate is higher than 2 MHz.