Abstract

Abstract
A versatile time-domain OCT system is presented which, for the first time, can generate cross-section images (B-scans) by using either transverse priority (T-scans) or depth priority (A-scans). Images from the optic nerve are obtained with either regime, with the same system. In different scanning regimes, different values are allowed for the maximum power to be launched to the eye. We present the maximum exposure level for a variety of scanning procedures, such as generation of cross section images and 3D volumes employing either A or T scanning.

Abstract
Third-order nonlinear and linear optical properties of nickel(II) and copper(II) complexes with salen ligands, functionalised with electron donor/acceptor groups (DA-salen), have been investigated in solution by the Z-scan technique using an Nd:YAG laser (lambda(inc) = 1064 nm) and UV/Vis spectroscopy. The [M(DA-salen)] complexes exhibit positive nonresonant nonlinear refractive indexes (net) in the range 27.0-8.50 center dot 10(-21) m(2)W(-1) and nonlinear absorption coefficients (a(2)(I)) within the range 1.80-26.0 center dot 10(-17) mW(-1). The latter values correspond to less than 10% of the overall magnitude of the third-order susceptibility, vertical bar chi(3)vertical bar, which is the result of the absence of electronic transitions near lambda(inc) = 1064 nm. For the group of N-II complexes, the highest net values are exhibited by the complexes with aromatic diimine bridges and large pi-electron delocalisation, which leads to intense electronic charge-transfer bands (epsilon > 16000 mol(-1) dm(3) cm(-1)) in the region lambda = 275-500 nm. The complexes that exhibit charge-transfer bands near lambda(inc)/2 = 532 nm, also show the highest a(2)(I) values, a consequence of multiphoton absorption processes. For the group of Cult complexes, the highest net value is also observed by the complex that exhibits the most intense charge-transfer bands in the region lambda = 275-475 nm. Between Ni-II and Cu-II complexes with the same DA-salen ligands, those of copper show always higher net values, indicating that NLO responses can also be fine-tuned by the metal centre. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Abstract
Can entanglement and the quantum behavior in physical systems survive at arbitrary high temperatures? In this Letter we show that this is the case for a electromagnetic field mode in an optical cavity with a movable mirror in a thermal state. We also identify two different dynamical regimes of generation of entanglement separated by a critical coupling strength.

Abstract
The performance of a high-pressure xenon gas proportional scintillation counter/microstrip gas chamber (GPSC/MSGC) hybrid detector has been investigated for filling pressures from 1 up to 10 bar, for 22-, 30- and 60-keV photons. GPSC/MSGC hybrid detectors are based on a xenon-GPSC instrumented with a CsI-coated microstrip plate photosensor placed directly within the xenon envelope, as a substitute for the photomultiplier tube. This design avoids the constraints due to the use of a quartz scintillation window for GPSC-photosensor coupling, which absorbs a significant amount of scintillation and is a drawback for applications where large detection areas and high filling pressures are needed. The lowest energy resolutions are achieved for 2 bar (5.5% and 3.4%, FWHM, for 22- and 60-keV photons, respectively). Increasing the pressure to the 5-6 bar range, competitive energy resolutions of 7 % and 4.5 % are still achieved for 22- and 60-keV photons, respectively. This detector could be a compelling alternative in applications where compactness, large detection area, insensitivity to strong magnetic fields, room temperature operation, large signal-to-noise ratio and good energy resolution are important requirements.

Abstract
The purpose of this work was to develop a design methodology for the fabrication of proton exchanged channel waveguides in LiNbO3 operating in the singlemode regime at several wavelengths, with specific characteristics required to optimize integrated devices. To achieve this, it is necessary to obtain the relations between the optical characteristics of the waveguides and their respective fabrication conditions, and to introduce models of the waveguide formation process. The relations between fabrication conditions and optical characteristics of planar waveguides realized by proton exchange in benzoic acid are documented extensively in the literature. However, reports on the characterization of waveguide fabrication processes, performed in a systematic way, could not be found, resulting in the need to combine information from several sources. Discrepancies among results from different researches are evident, resulting from different experimental methodologies and calibration of equipment. Therefore, aiming at extracting a consistent data set, optical characterization techniques of the refractive index profile were employed to study series of samples.