Sub-Doppler spectroscopy of Rydberg atoms via velocity selection memory in a hot vapor cell.

We study resonance redistribution mechanisms inside a hot vapor cell. This is achieved by pumping cesium atoms on the 6S→6P resonance and subsequently probing the velocity distribution of the 6P population by a linear absorption experiment on the 6P→16S or 6P→15D transitions at 514 nm and 512 nm, respectively. We demonstrate that despite the existence of thermalization processes, traces of the initial velocity selection, imposed by the pump, survive in hyperfine levels of the intermediate (6P) state.

Intensity correlation scan (IC-scan) technique to characterize the optical nonlinearities of scattering media.

Light scattering, whether caused by desired or spurious elements, is considered one of the main phenomena that present great challenges for the nonlinear (NL) optical characterization of turbid media. The most relevant disturbing factor is the random deformation suffered by the spatial intensity distribution of the laser beam due to multiple scattering. In this work, we report the intensity correlation scan (IC-scan) technique as a new tool to characterize the NL optical response of scattering media, by taking advantage of light scattering to generate speckle patterns sensitive to wavefront changes induced by the self-focusing and self-defocusing effects.

Ordered photonic colloidal suspensions.

Ordered photonic structures (photonic crystals) have seen increasing interest in recent years due to their potential applications, which depend on fabrication technologies suitable for mass production. In this paper, we studied by light diffraction the order in photonic colloidal suspensions composed by core-shell ( @ ) nanoparticles suspended in ethanol and water solutions. Light diffraction measurements show order in these photonic colloidal suspensions, being stronger in ethanol compared with suspensions in water.

Localization of light induced in ordered colloidal suspensions: powerful sensing tools.

We study the light-matter coupling by Raman scattering in colloidal suspensions composed by core-shell TiO@Silica (Rutile@Silica) nanoparticles suspended in ethanol and water solutions. Strong enhancement of the Raman signal per particle is observed as [TiO@Silica] is increased above a threshold, being stronger in ethanol suspensions. Moreover, above this [TiO@Silica] threshold, the optical transmittance of the ethanol suspension starts to be considerably lower than in water, despite scattering strength being higher in water.

Selective reflection technique as a probe to monitor the growth of metallic thin film on dielectric surfaces.

Controlling thin film formation is technologically challenging. The knowledge of physical properties of the film and of the atoms in the surface vicinity can help improve control over the film growth. We investigate the use of the well-established selective reflection technique to probe the thin film during its growth, simultaneously monitoring the film thickness, the atom-surface van der Waals interaction, and the vapor properties in the surface vicinity.

Two-beam nonlinear Kerr effect to stabilize laser frequency with sub-Doppler resolution.

Avoiding laser frequency drifts is a key issue in many atomic physics experiments. Several techniques have been developed to lock the laser frequency using sub-Doppler dispersive atomic lineshapes as error signals in a feedback loop. We propose here a two-beam technique that uses nonlinear properties of an atomic vapor around sharp resonances to produce sub-Doppler dispersivelike lineshapes that can be used as error signals.

Diode laser frequency locking using Zeeman effect and feedback in temperature.

We demonstrate the stabilization of a laser diode frequency, using the circular dichroism of an alkali vapor and feeding back the correction signal to the temperature actuator of the junction. The conditions of operation and the performance of such a system are discussed.