Optical coherence tomography (OCT) is a new imaging technique widely used in ophthalmic disease diagnosis and other measurement and detection fields. A swept source OCT (SS-OCT), as a main technical path of OCT, has become the research focus in the field of OCT in recent years because of its advantages of fast imaging speed, deep depth, and high resolution. Because the performance of SS-OCT is mainly determined by the performance of the frequency swept laser, the research and development of the frequency swept laser are very important. This paper mainly summarizes the research progress of frequency swept laser. From the aspects of technical means, design ideas, performance indicators, etc., the research progress of frequency swept laser and the research status of the frontier in the field are introduced and summarized in detail.