Abstract
A Temperature-independent strain sensor based on Four-Wave Mixing (FWM) using Raman fiber Bragg grating (FBG) laser sensor with cooperative Rayleigh scattering is proposed. Two FBG were used to form two linear cavities laser sensors based on Raman amplification combined with cooperative Rayleigh scattering. Due to the low dispersion coefficient of the fiber, it is possible to obtain the FWM using the two Raman FBG laser sensors. This configuration allows the operation as a temperature-independent strain sensor where both sensors are sensitive to temperature but only one of the FBG is sensitive to strain. The FWM efficiency is thus dependent on the applied strain but independent to the temperature.

Abstract
The use of fiber Bragg grating sensors embedded in hybrid composite laminates for simultaneous measurement of strain and temperature is proposed. The hybrid structure, formed by a pre-impregnated thermoset and thermoplastic composites, contains one single fiber Bragg grating embedded in each material, connected in series with each other. A different response is observed when the smart composite laminate is subjected to strain and to temperature. This is expected due to the distinct properties presented by each material. The rms deviation obtained for a temperature range between 20 and 60 degrees C is +/- 0.97 degrees C and for a strain range from 0 to 1100 mu epsilon is +/- 13.04 mu epsilon.

Abstract
A suspended multicore fiber sensor for simultaneous measurement of curvature and strain is proposed. The spectral response shows evidences of several interferences arising from the seven cores of the fiber. Once the sensing head presents different sensitivities for curvature and strain measurements, these physical parameters can be discriminated by using the matrix method. The rms deviations are +/- 19m(-1) and +/- 12:90 mu epsilon for curvature and strain measurements, respectively. (C) 2011 Optical Society of America

Abstract
Several configurations of ultralong Raman fiber lasers (URFL) based on a distributed mirror combined with Bragg gratings or fiber loop mirrors are studied. Two continuous-wave URFL configurations, with single and cascaded cavities using fiber Bragg gratings as mirrors are explored for a 300 km long fiber. For optical sensing, the cavity length was optimized for 250 km using one of the gratings an intensity sensor. Another URFL configuration based in a fiber loop mirror is also reported. For optical sensing using a 300 km long fiber it is shown that the best choice is a hybrid configuration. The sensitivity of the FBG laser sensor range was from (76 +/- 2) x 10(-6) mu epsilon(-1) (for lower strain) to (9.0 +/- 0.4) x 10 -6 mu epsilon(-1) (for higher strain). (C) 2011 Optical Society of America

Abstract
The properties of a Brillouin-Raman comb fiber laser are compared for two different configurations: co-propagating and counter-propagating Raman pump. The optical spectrum is compared for changing the Raman pump power and the power or the wavelength of seed laser. A Brillouin-Raman comb with 400 linewidth lasers in a flat-amplitude bandwidth of 32 nm between 1538 and 1570 nm, with an average optical power 20 dB above the nearby frequencies was generated. The lasers in the comb had an OSNR of 20 dB and a wavelength spacing of 0.08 nm. The results for the counter-propagating configuration were observed to have better quality.

Abstract
A temperature-insensitive strain sensor based on Four-Wave Mixing (FWM) using two Raman fiber Bragg grating (FBG) lasers with cooperative Rayleigh scattering is proposed. Two FBG were used to form two linear cavities laser sensors based on Raman amplification combined with cooperative Rayleigh scattering. Due to the very low dispersion coefficient of the fiber, it is possible to obtain the FWM using the two lasers. This configuration allows the operation as a temperature-insensitive strain sensor where both sensors have the same sensitivity to temperature but only one of the FBG laser is sensitive to strain. The difference between the wavelengths of the signal sensor and the converted signal presents a strain coefficient sensitivity of 2 pm/mu epsilon with insensitivity to temperature. The FWM efficiency is also dependent on the applied strain, but it is temperature independent, presenting a maximum sensibility of 0.01 dB/mu epsilon.