A tunable laser using double-ring resonator external cavity via free-carrier dispersion effect

A tunable laser based on double-ring external resonant cavity is designed, fabricated and tested. The double-ring resonator external cavity consists of a silicon waveguide ring resonator, a p-i-n doped silicon ring resonator, and a superluminescent diode (SLED). The laser is fabricated on a SOI wafer and the wavelength is tuned by injecting electrical currents to p-i-n structures. In the experiment, it measures 45.8 nm wavelength tuning with 110 GHz channel spacing and the average output power is approximately -8 dBm. It advances in high tuning speed, large side mode suppression ratio, and low manufacture cost, such has potential applications in high speed WDM networks.