10-Gb/s Tunable External Cavity Laser Using an Asymmetric Ring Resonator Reflector

We demonstrate a 10-Gb/s tunable external cavity laser with a polymer Bragg reflector and a highly integrated semiconductor gain chip including an asymmetric ring resonator reflector. The output power of the tunable laser is increased by adjusting the coupling strengths of two multimode interferences (MMIs) of the ring resonator reflector. The output power of the tunable laser is 6 mW at gain and semiconductor optical amplifier currents of 100 mA, and at a temperature of 25°C when the cross-coupling strengths ratios of two MMI couplers are 0.36 and 0.5. The tunable laser successfully provides 10-Gb/s transmissions through 20-km standard single mode fiber (SMF). The power penalty of the tunable laser is less than 2 dB after a 20-km SMF transmission for a 16-nm tuning range. The power penalty variation is less than 2 dB during the blue-shifted wavelength tuning.