Analysis And Design Of A Terahertz Generation System By Photomixing Working At 1550 Nm

The terahertz technique has attracted much attention from a variety of applications in fundamental and applied research field, such as physics, chemistry, life sciences, medical imaging, safety inspection, radio astronomy, modern communication and so on. The technological progress of terahertz radiation source plays an important role in promoting the development of various terahertz technique and the related cross subjects. At present, photomixing is the most promising continuous-wave terahertz source as potentially compact, easy-integration, low power consuming, low-cost, room temperature working, and the frequency of the generated terahertz signal can be easily tuned by tuning the central frequency of the pump lases. So this technology has been extensively studied.In this dissertation, a new terahertz photomixer which can be operated at 1550 nm and integrated the antenna structure is presented for the first time. Theoretical analysis and numerical simulation results showed that: the power and frequency of the output terahertz wave are the functions of the applied bias, physical parameter of photoconductor film, parameter of the pump lases and the size of the photomixing area and the substrate. Furthermore, A volume bragg grating external cavity dual-wavelength semiconductor laser is designed as the pump source of the terahertz photomixing system, the dual-wavelength output characteristics are analyzed by the equivalent cavity model theory.Compared with the traditional photomixing systems, the new photomixing system studied in this dissertation has the following characteristics: the operating wavelengths are shifted to 1550 nm, so it is enabled to take the advantage of the more mature technology in optical communication system, such as the wavelength-tunable lase diodes and so on. The photomixing area is simultaneously designed as a microstrip antenna and the terahertz signal is directly emitted from this area, this design is helpful to solve the serious impedance mismatch question. Furthermore, as the additional antenna structure in the traditional photomixer are omitted, the structure of the photomixer becomes more simple.