Dynamic interrogation of long period gratings with modulated fibre Bragg gratings
J. P. Carvalho, L. Coelho, INESC Porto - Institute for Systems and Computers Engineering of Porto (Portugal); L. Correia, Military Institute of Engineering (Brazil); O. Frazão, P. A. S. Jorge, J. M. Baptista, I. Dias, J. L. Santos, INESC Porto - Institute for Systems and Computers Engineering of Porto (Portugal); J. Weyl, Federal University of Pará (Brazil); M. J. Pontes, Federal University of Espírito Santo (Brazil); M. A. Martinez, CEFET-RJ - Federal Centre of Technological Education-Rio de Janeiro (Brazil); A. P. Barbero, R. M. Ribeiro, Fluminense Federal University (Brazil); A. J. G. Abelém, Federal University of Pará (Brazil); M. T. R. Giraldi, Military Institute of Engineering (Brazil)
It is reported a LPG dynamic interrogation technique based on the modulation of fibre Bragg gratings located in the readout unit that permits to attenuate the effect of the 1/f noise of the electronics in the resolution of the LPG-based sensing head. The concept is tested to detect variations of the external refractive index and a resolution of 2.0×10−4 NIR was achieved without system optimization. Additionally, the effect in the sensor resolution when introducing Erbium and Raman optical amplification is experimentally investigated.
