Resonant THz sensor for paper quality monitoring using THz fiber Bragg gratings

We report fabrication of THz fiber Bragg gratings (TFBG) using CO2 laser inscription on subwavelength step-index polymer fibers. A fiber Bragg grating with 48 periods features a ~4 GHz-wide stop band and ~15 dB transmission loss in the middle of a stop band. The potential of such gratings in design of resonant sensor for monitoring of paper quality is demonstrated. Experimental spectral sensitivity of the TFBG-based paper thickness sensor was found to be ~ -0.67 GHz / 10 um. A 3D electromagnetic model of a Bragg grating was used to explain experimental findings

Low-Loss THz Waveguide Bragg Grating using a Two-Wire Waveguide and a Paper Grating

We propose a novel kind of the low-loss THz Waveguide Bragg Grating (TWBG) fabricated using plasmonic two-wire waveguide and a micromachined paper grating for potential applications in THz communications. Two TWBGs were fabricated with different periods and lengths. Transmission spectra of these TWBGs show 17 dB loss and 14 dB loss in the middle of their respective stop bands at 0.637 THz and 0.369 THz. Insertion loss of 1-4 dB in the whole 0.1-0.7 THz region was also measured. Finally, TWBG modal dispersion relation, modal loss and field distributions were studied numerically, and low-loss, high coupling efficiency operation of TWBGs was confirmed

Spectral behavior of thin film coated cascaded tapered long period gratings in multiple configurations

In this work the spectral response of cascaded tapered long period gratings coated by nano-sized polymeric films has been investigated as function of the surrounding medium refractive index (SRI). The investigation was aimed to identify the best configuration in terms of coated/not coated areas in order to fully benefit of the SRI sensitivity enhancement due to the modal transition mechanism of nano-coated long period gratings while preserving the fringes visibility

Highly sensitive bend sensor with hybrid long-period and tilted fiber Bragg grating

We demonstrate a new type of fiber optic bend sensor with a hybrid structure made up of a long period grating (LPG) and a tilted fiber Bragg grating (TFBG). The sensing mechanism is based on the spectrum of power transfers between the core and cladding modes from a TFBG located downstream from a LPG. We show that the curvature of a beam can be determined by the reflected power difference between the core mode and the recoupled cladding modes. We further provide design rules for the LPG and TFBG to optimize and linearize the sensor response. In addition, the temperature cross-sensitivities of this configuration are also investigated for two different types of fiber

Cahiers d'expériences : programme recherche-développement pour les formateurs : laboratoire d'optoélectronique /

O artigo tem por objeto o estudo das condições de produção social do grupo de profissionais da Igreja católica no estado do Rio Grande do Sul ao longo do século XX a partir da apreensão dos determinantes do fenômeno de construção de um "celeiro de vocações". A análise do complexo investimento religioso no enquadramento de populações majoritariamente rurais ou semirrurais, compostas por famílias muito numerosas, de forte prática religiosa e desprovidas de recursos demonstrou o sistema de fatores objetivos a agir na produção de abundantes "vocações" religiosas em indivíduos dotados de propriedades sociais bastante homogêneas. O exame das vivências e das lógicas de engajamento individual do processo de conversão religiosa, explorado através de um conjunto de relatos de profissionais da Igreja, indica a constante combinação de tarefas pedagógicas relativamente sutis e eufemizadas de construção de percepções subjetivas sobre a religião, a vocação e as oportunidades ofertadas pela vida religiosa

Guide pédagogique : programme recherche-développement pour les formateurs : laboratoire d'optoélectronique /

Bibliogr. à la fin du v

Internet-based distributed data acquisition system for fiber-optic sensors

This paper describes an internet-based distributed data-acquisition system for fiber-optic pressure sensors. There is a great need in industry to coordinate remote resources to perform a common task. The architecture described is based on remote access, via the internet, to a large number of fiber-optic pressure sensors located in different geographical areas. Distribution is done with server applications, which schedule requests for service and control the actual sensor device. Servers also detect conflicts between new requests and their current schedules. Client applications act as virtual instrument panels that dispatch measurement tasks for servers. The architecture supports multiple sensors, which can be added/removed from the system dynamically. As well, there can be multiple clients attempting to access servers simultaneously. Thus, the sensors in question are publicly shared among the various active client applications