Theoretical analysis of microstructured gradient-index lens for THz photonics using Greens function integral equation methods

The optics of a micro-structured gradient-index lens for monolithic integration with THz photoconductive antennas is studied theoretically using Greens function integral equation methods. The lens design is based on etching sub-wavelength trenches into a semiconductor surface with varying width and spacing to create a microstructured material with a graded effective refractive index.