R. J. Knize

CO 2 laser trap for cesium atoms

We demonstrate a quasi-electrostatic trap for cold Cs atoms, using a focused 20-W CO(2) laser beam (lambda = 10.6 microm). Excluding background gas collisions, we measure a trap loss rate of 0.30(33) atoms/s, which is consistent with the calculated photon-limited loss rate of 3 x 10(-11) atoms/s. We measure a ground-state hyperfine population relaxation lifetime of at least 10 s.

Quasi-electrostatic trap for neutral atoms☆

We show that it is possible to trap any neutral atom using a focused high power infrared laser. The trap could hold several different species of atoms simultaneously. Small photon scattering and heating rates allow the possibility of long trap lifetimes.

A thin atomic vapor as a nonlinear optical medium

We demonstrate efficient degenerate four‐wave mixing in a 10 μm cell of cesium atomic vapor using resonant light. This thin atomic vapor can be utilized for processing high resolution images in a joint transform optical correlator. A figure of merit is presented showing that thin atomic vapors can perform optical correlation of images using fewer photons than other materials.

Efficiency of degenerate four-wave mixing in a two-level saturable absorbing medium.

Degenerate four-wave mixing in a two-level saturable absorbing medium is calculated on and off resonance for arbitrary input laser intensities and absorption coefficients. The maximum efficiency occurs at laser intensities higher than saturation in an optically thick medium. On resonance, the maximum efficiency can approach ∼4%, and it can be as large as 25% when the laser is tuned off resonance.

Polarizability of a free electron gas confined to a spherical shell

Abstract The linear polarizability and hyperpolarizability of a free electron gas confined to a spherical shell are calculated. This free electron gas model is applied to determine the polarizabilities of fullerene molecules. The magnitude of the calculated polarizabilities of C60 and C70 molecules were found to be in reasonable agreement with some of the experiments. The hyperpolarizability of the larger fullerene molecules is predicted to increase as the cube of the number of carbon atoms.

Measurement of the lifetime of the atomic cesium 5 2 D 5/2 state with diode-laser excitation

The lifetime of the atomic cesium 5(2)D(5/2) state was measured with time-correlated single-photon counting spectroscopy. Ground-state cesium atoms were excited with a diode laser by use of an electric quadrupole transition. Analysis of the exponential decay of the cascade photons from the 6(2)P(3/2) state yields a 5(2)D(5/2) lifetime of 1225(12) ns.

Reduced angular dependence for degenerate four‐wave mixing in potassium vapor by including nitrogen buffer gas

Degenerate four‐wave mixing in alkali vapors exhibits a strong dependence on the angle between the forward pump and probe beams, due to atomic motion. We show that this angular dependence is dramatically decreased by including several hundred Torr of N2 buffer gas in a potassium vapor cell. The angle at which the signal has decreased by half is 250 mrad, an improvement of over 50 times the angle for potassium vapor without buffer gases.

Optical NOR gate using cesium vapor.

The transmission of light at the S((1/2))-P((1/2)) resonance in an alkali vapor is strongly dependent on the laser polarization. This polarization dependence can cause a nonlinear interaction between different lasers so that one laser can be used to control the transmission of another laser. An optical NOR gate is demonstrated by using this nonlinearity in a cesium vapor cell.

Laser preparation of cesium atoms for degenerate four-wave mixing

Abstract We show that the nonlinear optical response of an atomic vapor can be enhanced by the utilization of a second laser which selectively alters the atomic populations. We use a second, state-preparation laser to assist the degenerate four wave mixing and observe a signal at a non-cyclic transition in cesium vapor. In the absence of this state-preparation laser, the non-cycling transition is subject to optical pumping and consequently the four wave mixing signal is not observed.

Optical correlator that uses cesium vapor

We obtain the correlation pattern between two amplitude-modulated input images of 36 and 280 random black and white pixels, using the standard degenerate four-wave-mixing geometry of 852-nm optical beams in a 1-mm-thick cesium-vapor cell. The total optical input power is 3.2 mW to obtain 0.4 nW of power in the correlation pattern. We verified that the buildup time of the four-wave-mixing signal is ~30 ns. Using the random patterns, we analyze the performance of the cesium optical correlator in terms of the number of pixels that can be processed and the number of photons per pixel used. We show how to scale our experimental results for the efficiency of the cesium correlator to images containing a larger number of pixels.