© 2014 IEEE. A radio over fiber (RoF) transmission system based on a gain-switched laser as an optical comb source is proposed and demonstrated. 10-Gb/s 16 quadrature amplitude modulation (16QAM) signal generation and transmission over 25-km standard single-mode fiber (SSMF) is experimentally demonstrated using a 60-GHz carrier. The phase noise on the 60-GHz carrier induced by the time delay between the selected two optical tones from the comb source is explored, and its effect on system performance is investigated.