Journal of the Physical Society of Japan
A Three-Dimensionally Isotropic and Perfectly Vacuum-Impedance-Matched Negative-Index Material
Jian Qi Shen
Abstract
A new scenario for realizing a gain left-handed atomic vapor medium based on both dressed-state mixed-parity transitions (for simultaneous electric- and magnetic-dipole resonance) and incoherently-pumped population transfer (for high gain amplification) in a four-level atomic system is suggested. Dressed-state assisted simultaneous electric- and magnetic-dipole allowed transitions in such a four-level atomic system (of, e.g., neutral alkali-metal atoms such as lithium and potassium atoms) are utilized for achieving negative refractive index with impedance perfectly matched to vacuum. The attractive features of the present scenario include: i) three-dimensionally isotropic negative indices; ii) incoherent-gain wave amplification; iii) perfect impedance matching to vacuum. All these important properties of the double-negative medium would have potential applications in designing some optical and photonic devices, including particularly subwavelength focusing system and negative-index superlens for perfect imaging.