Abstract

Squeezed states of light with reduced quantum noise in one quadrature of the light field can be generated by parametric processes in atomic or solid systems. The solid systems, in principle, have the advantage that the ratio of the nonlinear (lossless) interaction to the losses in the solid required to generate the squeezed state can be much larger than the corresponding ratio for an atomic system. In the atomic system, losses are dominated by the Lorentzian absorption tail, decreasing as the inverse square of the frequency shift from resonance. Absorption losses in solids can decrease exponentially (or even faster) at frequencies below an absorption band or an exciton feature while the nonresonant nonlinear response decreases slowly, often with a power-law dependence. We concentrate on the third-order susceptibility for a broad class of semiconductors (e.g., GaAs) and organic materials (e.g., polydiactylene) where losses can be very low. The ratio of nonlinearity to loss required for significant squeezing of light noise is in the same range as that required for a good optical switch. A nonlinear phase shift of ir is required while losses are reduced so that only a small fraction of the incident light is absorbed. Several solid systems show promise for obtaining large squeezing for photon energies just below the exciton band-edge feature. Enhanced nonlinearity is also obtained at the threshold energy for two-photon absorption. Present crystal growth technologies can decrease losses due to impurities into a very optimistic regime for squeezed state generation.

© 1986 Optical Society of America