Reflectionless tunneling of infrared radiation through subwavelength slit in a waveguide

摘要

A new effect of resonant tunneling of a fundamental mode of optical radiation through a subwavelength slit formed by smoothly shaped narrowing of a waveguide is examined. An effective energy transfer by evanescent waves is shown to be determined by the geometry of curvilinear narrowing. Spectra of reflectionless transmittance for waves 2.5-3 times longer than the width of the slit are found. Dependence of resonant tunneling on the geometrical parameters of narrowing and splitting of resonant maxima resulting in formation of two peaks of tunneling transmittance are demonstrated. An additional insight into the properties of narrowed waveguides has been obtained through the visualization of the variation of the field patterns associated with the modes for a specific configuration and the wavelength.