We report a novel single-cavity dual-wavelength laser that has two distributed Bragg reflector (DBR) gratings at each side of a gain section for THz communication applications. By varying the inject current of one of the DBR gratings, the optical beat frequency of the laser can be widely tuned. In the device, a high-speed electro-absorption modulator (EAM) is also integrated and can be used for up to 25 Gb/s data modulation.