Efficient Terahertz Wave Generation via Second-order Nonlinearity in AlxGa1-xAs Material System

The thesis aimed at generating 1- and 2-THz light in AlxGa1-xAs semiconductor chip through difference frequency generation using chi(2) nonlinearities. The pump and signal wavelengths were targeted around half of the material bandgap. The thesis develops two designs, namely Terahertz Lateral Bragg Reflection Waveguide (THz-LBRW) and Integrated Coplanar Strip (ICPS). The technique employed to achieve the exact phase matching condition in the THz-LBRW is based on engineering the phase velocity of the guided THz mode. The guided THz mode is a Bragg mode where its mode index is tuned to match the group index near the signal wavelength. On the contrary, the ICPS engineers the group index at the signal wavelength; such that, it is decreased to match the mode index of the generated THz light that is guided by coplanar strip. The efficiencies of 25.6[nW/W^2] and 4.9[nW/W^2] were obtained through optimization of the THz-LBRW and ICPS, respectively. Both structures are practical and manufacturable and the thesis presents the fabrication result for the THz-LBRW sample where the linear propagation loss of 10[/cm] was measured. The full fabrication process of the ICPS design is developed and its important partial results are reported.MAS