Spontaneous nonparametric down-conversion of light

Ievgen I. Arkhipov

Iu. M. Golubev, В. Н. Горбачев

Nafia Rahaman, Russell McLean, A. M. Akulshin

Frequency up- and down-conversion in warm alkali vapours over a range of applied cw laser intensities has received much attention in recent years due to promising applications in the fields of remote detection, quantum information and computing, specifically in the implementation of correlated photon pairs, photon storage and quantum memory interface to name a few. The generation of directional laser-like blue and infrared light in alkali vapours has been extensively studied. However, important details of the interplay of parametric and nonparametric nonlinear processes, such as the four-wave mixing (FWM) and amplified spontaneous emission (ASE) responsible for the new field generation, are not entirely clear.

Arne Skov Jensen

Brian J. DeBoo, Derek F. Jackson Kimball, C.-H. Li +1 more

Collimated and conical emissions that appear when Yb vapor is illuminated by light pulses at 262 nm (near the one-photon Yb 6s2 1S0→6s7p 3P1 transition) are experimentally investigated. Conical emission is observed at multiple wavelengths. Parametric and nonparametric nonlinear optical processes are studied by investigation of the spatial distribution of generated light and the efficiency of light generation as a function of the incident light frequency.

Thomas A. DeTemple, M. Gurnick, François Henri Julien

The density-matrix approach, in the quasistatic or adiabatic limit, is applied to the case of resonant four-wave interactions in four-level systems resulting in explicit analytical expressions for the nonlinear optical parametric and nonparametric polarizations, including ac Stark effects. The results are applicable to any closed-linkage diagram of this type but are applied only to the specific case of resonant frequency tripling. The results revealed the presence of up to six Stark-shifted nonparametric resonances and the presence of saturation and interference effects on the parametric susceptibility. In particular, the third-order susceptibility is shown to saturate to a very small value under high-field conditions which restricts the range of useful pump intensities. Under near-resonant to resonant conditions, these imply that because of either nonparametric loss present at the pump or harmonic frequencies or power-dependent dispersive and saturation effects, conversion efficiencies higher than 25% may be difficult to realize in practice.