1.3-μm dual-wavelength DFB laser chip with modulation bandwidth enhancement by integrated passive optical feedback

We report a 1.3-μm dual-wavelength distributed feedback (DFB) photonic integrated chip with modulation bandwidth enhancement using integrated optical feedback section. The dual-wavelength DFB lasers were realized using the upper separate confinement heterostructure (SCH) selective area growth (SAG) approach. A modified butt-joint technique was also adopted to achieve high-quality active-passive interface and minimize unintentional intra-cavity optical feedbacks. The fabricated photonic chip exhibited stable single mode operations with a wavelength separation of 2.06 nm. The 3-dB modulation bandwidth was enhanced through the photon-photon resonance effect with f_3dB > 17 GHz and open eyes up to 25 Gbit/s for both channels were also obtained. The design can also be scaled up to higher channel counts and higher data rate.