A theoretical investigation of tunable terahertz (THz) plasmonic lenses on the basis of InSb microslits is presented.First, it is demonstrated that the surface plasmon polaritons propagating in an InSb microslit array with variant slit widths would face different phase retardations, which, by design, can produce a focusing wavefront. The extraordinary transmission of THz radiation through the InSb subwavelength slit array is also observed. Second, a method for tuning the focal lengths of InSb plasmonic lenses is proposed. The results in this article provide a potential way to realize a tunable terahertz plasmonic lens with high transmission, which can be applied to the application of rapid 3D z‐scanning based THz imaging and sensing. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:979–981, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25079

The energy band structure of a transparent, green, room-temperature ferromagnetic FeBO3 has been calculated using density functional theory within the generalized gradient approximation (GGA) and the GGA+U approach. The electronic structure of FeBO3 is predicted to be antiferromagnetic and insulating, both in perfect agreement with available experiments. The predicted band structure, in particular, the shapes of the valence and conduction band edges, provides great insights into tailoring the optical band gap of FeBO3 nanoparticles: for the particle size close to 3nm, the visible spectral region extends from green up to blue due to quantum confinement.

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