Polariton-enhanced near field lithography and imaging with infrared light

摘要

A novel approach to making a material with negative index of refraction in the infrared frequency band is described. Materials with negative dielectric permittivity ε are utilized in this approach. Those could be either plasmonic (metals) or polaritonic (semiconductors) in nature. A sub-wavelength plasmonic crystal (SPC), with the period much smaller than the wavelength of light, consisting of nearly-touching metallic cylinders is shown to support waves with negative group velocity. The usage of such waves for sub-wavelength resolution imaging is demonstrated in a numerical double-slit experiment. Another application of the negative-epsilon materials is laser-driven near field nanolithography. Any plasmonic or polaritonic material with negative ε = -ε_d sandwiched between dielectric layers with ε_d > 0 can be used to significantly decrease the feature size. It is shown that a thin slab of SiC is capable of focusing the mid-IR radiation of a CO_2 laser to several hundred nanometers, thus paving the way for a new nano-lithographic technique: Phonon Enhanced Near Field Lithography in Infrared (PENFIL). Although an essentially near-field effect, this resolution enhancement can be quantified using far-field measurements. Numerical simulations supporting such experiments are presented.