Chirality and Negative Refraction without Absorption in the Optical Domain Using Electromagnetically Induced Transparency

Nonclassical light beams generated by degenerate and non-degenerate optical parametric oscillators （OPO） have played a significant role in studies of squeezing, entanglement and other nonclassical properties of light. Fluctuation properties of these nonclassical light beams have been studied by using various coherent state representations of the field density matrix. Here we discuss the use of positive-P representation of the density matrix to map nonlinear quantum dynamics of an OPO onto c-number stochastic equations. Insights gained from these equations eventually lead to analytical expressions for positive-P function both for the degenerate and nondegenerate OPOs. Using these distributions we derive simple analytic expressions for various experimentally measurable quantities such as mean light intensity, intensity variance, squeezing, and photon counting distributions. Each of these quantity is described by a single unified analytical expression valid below, near and above threshold. We investigate how these properties are transformed near threshold as the oscillator makes a transition from below to above threshold. The results for the OPOs are compared with those for the single-mode and two-mode lasers and their similarities and differences are discussed.

Chirality and Negative Refraction without Absorption in the Optical Domain Using Electromagnetically Induced Transparency

Destructive and constructive interference effects in multi-level systems with coherently coupled magnetic and electric dipole transitions can lead to enhanced chirality at a frequency where resonant absorption is suppressed. The enhanced chirality yields a negative index of refraction for densities much less than those needed to achieve negative permeability. The required densities however exceed the value of one active atom per wavelength cubed such that local field corrections need to be taken into account. We find that these effects can substantially improve the refraction-absorption ratio.