Full $C$-Band Tuning Operation of Semiconductor Double-Ring Resonator-Coupled Laser With Low Tuning Current

A widely tunable double-ring resonator-coupled laser is developed for use in a photonic packet switching system. By using a double-ring resonator as a wavelength-selective filter, full -band tuning operation is achieved with a low tuning current, and the fabrication process is simpler than that used for distributed-Bragg-reflector-type tunable lasers. A tuning range of 50.0 nm with a current injection of less than 7 mA is successfully demonstrated.