Broadband antireflection coating for optimized terahertz beam splitters

We investigate the potential of anti-ferromagnetic nanofilms as broadband antireflection coatings in the terahertz frequency range. The anti-ferromagnetic layer is modeled by an analytic wave-impedance matching approach. The experimental results of the transmission and reflection measurements demonstrate the effectiveness of our antireflection coatings. Furthermore, we use anti-ferromagnetic nanofilms as antireflection coating for a terahertz beam splitter. Compared with conventional terahertz beam splitters consisting of an uncoated thick silicon wafer, the coated silicon beam splitter has two advantages: elimination of multiple reflections and improvement of the signal-to-noise ratio for terahertz time-domain spectroscopy in reflection geometry.