Widely tunable semiconductor optical fiber ring laser

A wide tunable optical fiber ring laser with a diffraction grating as a tuning element is demonstrated. A wide tuning range over 100 nm is achieved using a high performance traveling‐wave amplifier (TWA) as a gain medium. The TWA with a V‐grooved inner stripe structure on a p substrate (VIPS structure) has a high peak gain over 30 dB and a broad gain width of 100 nm at 16 dB. The effects of the gain of TWA and the total loss of the external ring cavity on the tuning range are also discussed.