Based on a semiconductor optical amplifier (SOA) and a high-speed fiber Fabry-Perot filter, we built a short ring cavity for producing high-speed swept laser. During the filter sweeping from the long wavelength to the short wavelength, if the bias current of the SOA was switched off, we could acquire a swept laser with a duty cycle of 50%. With the help of an interleaver, the swept laser with a duty cycle of 100% could be obtained. Furthermore, after a second SOA was applied, the output power of the swept laser was further improved. Finally, it was experimentally demonstrated that the swept laser featured a swept frequency of 500 kHz, a center wavelength of 1550 nm, a sweep range of 67 nm, an effective coherence length of 6.5 mm, and an average output power of greater than 20 mW.