Photonic Analog of Klein Paradox in a Periodic Layered Material with Composite Structure of Left-Handed Medium and Electromagnetically Induced Transparency.

A novel frequency-sensitive switching control effect induced by two-photon resonance for TM wave in a periodic layered medium containing left-handed material (LHM) and electromagnetically induced transparency (EIT) medium is suggested. Since the optical response of an atomic medium can be controlled via tunable quantum interference between multilevel transition pathways driven by an external control field, a periodic layered medium whose unit cells consist of left-handed medium and EIT atomic vapor can exhibit some intriguing properties: I) the band structure (and hence the reflection and transmission of light) will show flexible optical response sensitive to frequency, ii) an unusual Klein tunneling effect of light occurs in the present LHM-EIT-based medium, and iii) the controllable band structure depending on the external control field would have potential applications in designing new devices such as photonic switches, photonic logic gates and photonic transistors [ABSTRACT FROM AUTHOR]