Many applications of THz radiation require sources that are compact, low-cost, and operate at room temperature. In this project, a low-noise optically-controlled THz array antenna system will be developed, addressing a significant barrier in the adoption of THz technology. We will demonstrate a novel 'system on a chip', integrating a thin film antenna array, photodiode array, semiconductor optical amplifier (SOA) array and optical beam forming network. The SOA array enhances the pump power and ensures all array elements are evenly pumped. The beam former is used to control the phase difference between the THz radiation from different THz antennas, and thus scanning of THz beam can be realized. A THz repetition frequency mode-locked laser will be used as the light source to lock the phase of optical signals in the chip, greatly reducing the linewidth of the THz emission. The advantages of this THz emitter system include a high peak intensity due to radiation from the antennas combining coherently, room temperature operation, continuous-wave operation, compact form factor, and a narrow steerable beam. The sources will be assessed for use in systems for high-bandwidth wireless communications and for medical imaging.