Wafer-level integration of micro-lens for THz focal plane array application

Design and fabrication of dielectric lenses for terahertz (THz) focal plane arrays are presented in this paper. Lenses are designed using optical lens and ellipsoid function theory in the terahertz range (centered at f = 300GHz). In order to enhance coupling to planar circuits on wafer, two types of lenses are considered: modified hemispherical, such as extended hemispherical and hypo-hemispherical. Full wave analysis of the lens design is carried out both in near- and far-field regimes. The lenses are fabricated using a 3D plastic printer. An approach to use the 3D printed structure as a mold to fabricate micro-injection molded lenses is also introduced. Measured results on 3D printed lens array show high transmission characteristics and measured results correlate closely with simulation results.