Orlando Frazão

Publications (196) View all

• Article: Temperature and Strain Sensing With Femtosecond Laser Written Bragg Gratings in Defect and Nondefect Suspended-Silica-Core Fibers

  L A Fernandes, M Becker, O Frazao, K Schuster, J Kobelke, M Rothhardt, H Bartelt, J L Santos, P V S Marques
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  ABSTRACT: The spectral behavior in the C-band of fiber Bragg gratings (FBGs) was analyzed as a function of temperature and strain. The FBGs were fabricated in pure silica four-leaf-clover-shaped suspended-core fibers by (DUV) femtosecond laser exposure (3.6 W at 800 nm, 130 fs, 1 kHz frequency tripled to 350 fs, 650 mW at 267 nm). A defect fiber (with a hollow hole in the core) and nondefect fiber were compared both yielding ≈1 pm/μe sensitivity to strain but different sensitivity to temperature (from 3.0 pm/°C to 8.4 pm/°C for the defect fiber and 10 pm/°C for the nondefect fiber). The 16% to 70% relative difference between the thermal coefficients of the two fibers, together with their similar strain sensitivity enables the simultaneous measurement of strain and temperature.
  IEEE Photonics Technology Letters 04/2012; 24:554 -556. · 2.19 Impact Factor
• Article: Intrinsic Fabry–Pérot Cavity Sensor Based on Etched Multimode Graded Index Fiber for Strain and Temperature Measurement

  P.A.R. Tafulo, P.A.S. Jorge, J.L. Santos, F.M. Araujo, O. Frazao
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  ABSTRACT: Two Fabry-Perot interferometers based on chemical etching in multimode graded index fibers are fabricated and their response to temperature and strain are compared. Chemical etching is applied in the graded index fiber end creating an air cavity. The interferometric cavity is formed when the graded index fiber with the air concavity is spliced to a single-mode fiber. The intrinsic sensors present high sensitivity to strain and low sensitivity to temperature. For the 62.5 μm core fiber, sensitivities of 6.99 pm/με and, 0.95 pm/°C were obtained for strain and temperature, respectively. The sensor based in the 50 μm core fiber, on the other hand, presented sensitivities of 4.06 pm/με and -0.84 pm/°C for strain and temperature, respectively.
  IEEE Sensors Journal 02/2012; · 1.52 Impact Factor
• Source

  Available from: Orlando Frazão

  Article: Brillouin effect characterization in all-Raman amplified 4 40 Gb/s WDM system

  M. J. Pontes, M. E. V. Segatto, A. P. L. Barbero, M. T. M. Rocco Giraldi, A. M. Rocha, B. Neto, J. C. W. Costa, M. A. G. Martinez, O. Frazao, J. M. Baptista, H. Salgado, A. L. J. Teixeira, P. S. Andre
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  ABSTRACT: This article analyzes experimentally the limitations observed in a 45 km Raman amplified 4 x 40 Gb/s transmission system operating under multiple pump and single high pump power configurations. A signal-to-noise ratio of 19.2 dB, an extinction ratio of 10.4 dB and a jitter of 1097 fs are achieved for moderate pump powers and higher order stimulated Brillouin scattering lines give rise to system degradation for pump power levels more than 0.5 W. (C) 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:14031407, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26827
  Microwave and Optical Technology Letters 01/2012; 54(6):1403-1407. · 0.62 Impact Factor
• Source

  Available from: A. B. Lobo Ribeiro

  Article: Fiber-Optic Inclinometer Based on Taper Michelson Interferometer

  L.M.N. Amaral, O. Frazao, J.L. Santos, A.B. Lobo Ribeiro
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  ABSTRACT: A compact fiber-optic inclinometer based on a fiber-taper Michelson interferometric sensor is constructed and demonstrated. The sensor consist of a single symmetrically taper waist of 80 μm distanced 30 mm from the single-mode fiber end-tip right-angled cleaved. The amplitude of the bending angle of the fiber taper interferometer is obtained by passive interferometric interrogation based on the generation of two quadrature phase-shifted signals from two fiber Bragg gratings with different resonant wavelengths. Optical phase-to-bending sensitivity of ~ 1.13 rad/degree and a bend angle resolution of ~ 0.014 degree/√ Hz were achieved.
  IEEE Sensors Journal 10/2011; · 1.52 Impact Factor
• Article: Temperature-Independent Curvature Sensor Using FBG Cladding Modes Based on a Core Misaligned Splice

  C. Gouveia, P.A.S. Jorge, J.M. Baptista, O. Frazao
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  ABSTRACT: A fiber-optic curvature sensor based on a core offset single-mode fiber (SMF) combined with a fiber Bragg grating (FBG) is presented. The FBG cladding modes are efficiently excited by the large core misalignment. The curvature of the fiber can be obtained by the ratio between the recoupled cladding mode power and the reflected core mode power. These measurements are independent from temperature variation.
  IEEE Photonics Technology Letters 07/2011; · 2.19 Impact Factor