ABSTRACT
We propose and experimentally demonstrate a dual-wavelength distributed feedback (DFB) laser array utilizing a four-phase-shifted sampled Bragg grating. By using this grating, the coupling coefficient is enhanced by approximately 2.83 times compared to conventional sampled Bragg gratings. The devices exhibit a stable dual-mode lasing achieved by introducing further π-phase shifts at 1/3 and 2/3 positions along the cavity. These devices require only one stage of lithography to define both the ridge waveguide and the gratings, mitigating issues related to misalignment between them. A dual-wavelength laser array has been fabricated with frequency spacings of 320â GHz, 500â GHz, 640â GHz, 800â GHz, and 1â THz. When integrated with semiconductor optical amplifiers, the output power of the device can reach 23.6â mW. Furthermore, the dual-wavelength lasing is maintained across a wide range of injection currents, with a power difference of <3â dB between the two primary modes. A terahertz (THz) signal has been generated through photomixing in a photoconductive antenna, with the measured power reaching 12.8â µW.