Quantum Coherence in a Single Ion due to strong Excitation of a metastable Transition

We consider pump-probe spectroscopy of a single ion with a highly metastable (probe) clock transition which is monitored by using the quantum jump technique. For a weak clock laser we obtain the well known Autler-Townes splitting. For stronger powers of the clock laser we demonstrate the transition to a new regime. The two regimes are distinguished by the transition of two complex eigenvalues to purely imaginary ones which can be very different in magnitude. The transition is controlled by the power of the clock laser. For pump on resonance we present simple analytical expressions for various linewidths and line positions.Comment: 6 figures. accepted for publication in PR

Localization of absorption losses in oxide single-layer films

Absorption measurements performed by means of photoacoustic absorption (PAA)-technique in wedge-shaped TiO2' Ta2O5, and ZrO2 single-layer films at λ = 488 nm, 515 nm, and 647 nm permit a separate determination of bulk and interface absorption, respectively. For TiO2 and Ta2O5 films investigated the film-substrate interface absorption Afs dominates over the air-film interface absorption Aaf, whereas for evaporated ZrO2 films both the interface contributions are nearly the same. In addition, preliminary results concerned with the wavelength dependence of the absorption of the films investigated are presented.Les mesures d'absorption réalisées par la méthode de l'absorption photoacoustique dans des films TiO2, Ta2O5, et ZrO 2 en forme de coin à λ = 488 nm, 515 nm et 647 nm permettent de séparer l'absorption due au volume de celle due à l'interface. Pour les films de TiO2 et Ta2O5 l'absorption due à l'interface film-substrat est supérieure à l'absorption due à l'interface air-film, tandis que pour les films évaporés de ZrO2 les deux contributions sont comparables. De plus on donne les résultats préliminaires de la dépendance en fonction de la longueur d'onde de ces films

A proposal for the reconstruction of buried defects from photothermal images

The object reconstruction from synthesized and noisy photothermal signals was carried out by deconvoluting contrast scans by means of photothermal point spread function. The unknown defect depth parameter was estimated by minimizing the "imaginary content" of the deconvoluted real valued defect distribution. The algorithm shows remarkable accuracy even in the presence of 10%-noise in finding the true defect depth. Essential for its convergence is an effective noise suppression which we achieved by a modified Wiener filter

Photothermal characterization of laser-active Yb: Glasses

To design pulsed laser amplifiers detailed knowledge about beam distortions in the amplifying medium is needed. Time resolved probe beam deflection measurements from different laser glasses have been performed to study pump beam induced optical aberrations. By means of a wavelength tuned probe beam thermally induced variations of the optical path and beam narrowing effects due to the radial gain distribution could be distinguished. The experimental data were theoretically analyzed. Different behavior was found for two types of Yb:glass despite their similar nominative properties

Description of an interferometric photothermal microscope and its application to the study of semiconductor samples

A computerized scanning microscope is described which is equipped with a photothermal sensor. Two types of sensors have been developed both being based on probing the thermal lens above the heating spot by a Mach-Zehnder interferometer. One interferometer was built up from separate optical components while the other one was designed as a microoptical block connected by a gradient index lens and optical fibres with a laser diode and a photodiode. Measurements from structured semiconductors are presented demonstrating the performance of the photothermal microscope

Micromorphology of Gram-negative hydrogen bacteria - II. Cell envelope, membranes, and cytoplasmic inclusions.

The fine structure of the cell envelope, of membrane systems and of cytoplasmic inclusions of Gram-negative aerobic hydrogen bacteria has been studied. The results have been tabulated, and three main groups could be recognized: Group 1: Alcaligenes eutrophus, A. paradoxus, A. ruhlandii, Pseudomonas facilis, P. flava, P. pseudoflava, P. palleronii, and Aquaspirillum autotrophicum; Group 2: "Corynebacterium" autotrophicum and strains MA 2 and SA 35; Group 3: Paracoccus denitrificans. Special structures related to the chemoautotrophic way of life of the hydrogen bacteria were not observed

Micromorphology of Gram-negative hydrogen bacteria - I. Cell morphology and flagellation.

The cell morphology, the arrangement and fine structure of flagella and the piliation of the following Gram-negative aerobic hydrogen bacteria have been studied: Alcaligenes eutrophus, Alcaligenes paradoxus, Alcaligenes ruhlandii, Pseudomonas flava, Pseudomonas pseudoflava, Pseudomonas palleronii, Pseudomonas facilis, Aquaspirillum autotrophicum, Paracoccus denitrificans, Corynebacterium autotrophicum, and strains MA 2 and SA 35. The identity of the bacteria was examined by their substrate spectra and type of flagellation. Three types of flagellar fine structure were differentiated. The presence of pili was noted in strains of Alcaligenes paradoxus, Pseudomonas flava, P. pseudoflava, P. palleronii, and P. facilis

Optical losses of sputtered Ta2O5 films

Visible light scattering as well as absorption measurements have been made on sputtered Ta2O5 single layers with changing the optical thickness of the film. Comparison of the results experimentally observed with those obtained from theory allowed conclusions to be drawn with respect to the dominant origins of scattering and absorption losses.Des mesures de diffusion de la lumière visible ainsi que de l'absorption ont été réalisées sur des films de Ta2O5 pulvérisés, d'épaisseur variable. La comparaison des résultats expérimentaux avec la théorie permet de tirer des conclusions relatives à l'origine des mécanismes dominants dans la diffusion et l'absorption

Spatially resolved photomodulated microwave absorption and thermal wave images of boron doped silicon

A novel imaging technique for semiconductor samples, the photomodulated microwave absorption (PMA), is presented. The sample is placed in a microwave cavity and illuminated with a modulated focussed laser beam. The excited photo carriers disturb the distribution of the high-frequency electric field in the cavity and therefore change its quality factor. This change is accessible to the experiment. First results on a silicon sample with well defined boron doped areas (1015 cm-2) are resented and compared to Mirage experiments

Conditions for optimum photothermal discrimination of subsurface thermal inhomogeneities

We present calculated photothermal contrast functions arising from lateral scanning of buried stripe and disk-shaped deviations in thermal conductivity k. From the theoretical findings we derive the measuring conditions in terms of the modulation frequency for which optimal photothermal discrimination of subsurface thermal inhomogeneities can be achieved. The theoretical results have been verified experimentally by measuring model samples, in which localized inhomogeneities were embedded