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.

Abstract
In this work, numerical simulations are performed and the performance comparison of four types of dispersion compensating Raman/EDFA hybrid amplifiers configurations in terms of gain, noise figure and nonlinear effect induced penalty is presented. A numerical simulator is presented for the analysis and design optimization of Raman/EDFA hybrid amplifiers for multi-wavelength operation. This simulator combines a steady-state model of a discrete Raman Amplifier (RA) with a spectrally resolved model for the Erbiurn Doped Fiber Amplifier (EDFA). The numerical simulator allows us to calculate the overall gain, the noise figure (NF), the optical signal-to-noise ratio (OSNR) and the signal and ASE spectrum at the output of a Raman/EDFA hybrid amplifier. We concluded that performance tradeoffs should be considered when an optimum hybrid amplifier configuration for a given fiber optic transmission system is to be decided.

Abstract
This paper explores Ampere's circuital law (ACL) from an educational perspective. The interchangeability of the amperian loop with the current loop, an intrinsic symmetry of ACL that is seldom addressed in the literature or textbooks, is illustrated here. It is verified that the symmetry axis of a circular current is an amperian loop. The attempt to apply ACL to a finite wire, a common source of student misunderstanding, is used to highlight the limitations of ACL. The generalisation of ACL is illustrated using an instructive example where the displacement current is unconfined and not spatially uniform. This work is primarily intended for teachers and more advanced undergraduate students, who may benefit from the ideas that are presented here.

Abstract
A systematic investigation of erbium diffusion in lithium niobate (LiNbO3) crystal as a function of crystal cut-direction, diffusion process parameters (temperature and time), and initial film thickness is reported. Depth concentration profiles of erbium are obtained by secondary ion mass spectrometry (SIMS). Combining experimental data with diffusion theory, the relevant diffusion parameters are derived. Diffusion from an infinite source of erbium ions is studied to evaluate the solid solubility lower limit of Er in LiNbO3. A thin film diffusion regime, with complete depletion of ion source. is also investigated. A comparison of Er diffusion with Er/Ti codiffusion in LiNbO3 crystals is reported.

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