Abstract
We present the classical and quantum theory of time refraction in a generic nonstationary medium. The classical approach leads to expressions for the temporal refraction coefficient, and the temporal Fresnel laws are given. The quantum formulation leads to the derivation of instantaneous Bogoliubov transformations and the evaluation of the number of photon pairs created from vacuum by the temporal changes in the medium. The influence of boundary conditions, the connection of this model with the dynamical Casimir effect, and radiation from superluminal nonaccelerated optical boundaries is also discussed.

Abstract
The purpose of this work was to develop a design methodology for the fabrication of waveguides in LiNbO3 operating in the single-mode 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 titanium in-diffusion 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 calibrations of equipment. Therefore, aiming at extracting a consistent data set, optical characterization techniques for the refractive index profile were employed to study series of samples.

Abstract
The possibility of fabricating efficient optical amplifiers in LiNbO3, realized by localization of the dopant on surface areas was theoretically evaluated and the feasibility of fabricating efficient amplifiers in such doped structures was experimentally verified. The model of amplifiers based on 3-level laser systems realized by local doping incorporates dopant localization, the influence of the interaction length, as well as that of the effective pump area and of the pump power in the amplifier performance. It was verified that localized doping allows optimization of amplifier performance through adjustment of the active region geometry to the mode intensity profile. The experimental results confirmed that the width of the metal stripe deposited on the surface must be optimized so that gain is maximum, for a given value of the pump power. It was experimentally demonstrated that transverse localization of the active ions reduces the threshold pump power, which may be relevant for realization of integrated lasers in Er:LiNbO3.

Abstract
A new wavelength multiplexing configuration for self-referenced fiber optic intensity sensors using fiber Bragg gratings and wavelength division multiplexing (WDM) couplers is investigated. First, the network multiplexing concept is characterized, and then the self-referenced intensity sensor is presented, which is the basis of each individual sensor in the network. The implemented experimental setup of the multiplexing network is described, and results are presented considering the crosstalk, resolution, and power budget of the sensing multiplexing network. The characteristics and features of the configuration proposed are addressed. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

Abstract
A fiber optic sensing system for simultaneous measurement of temperature and salinity based on fiber Bragg grating technology is presented. The fabrication process, which relies on chemical etching of the fibre, is described and its performance is evaluated. Theoretical and experimental results are given, which are summarized on the obtained resolutions of +/-0.06degreesC/ rootHz and +/- 0.2parts per thousand./ rootHz for temperature and salinity, respectively. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

Abstract
Semiconductor nano-particles, or quantum dots, with their relatively high quantum yields, narrow luminescence spectrum, outstanding photostability and the ability to tune their optical properties, are ideal for biological tagging applications and a very powerful tool for chemical sensors. In this paper an overview of this rapidly expanding area of research is presented. Additionally, some results are shown, in the framework of optical oxygen sensors, which establish quantum dots as suitable temperature and intensity references for application in luminescence based chemical sensors.