A method for Raman Piezo-spectroscopic constants determination using femtosecond laser pulses interaction in Nd3+ doped MgO:LiNbO3 crystals

M.R. TEJERINA; G.A. TORCHIA

Playa del Carmen

Conferencia; Conference on Laser Ablation; 2011

Several papers show that after femtosecond (fs) laser interaction with materialsat high intensities it is possible to describe the residual stress and deformations byusing a plane strain model. This method takes into account the expansion of an ellipseinside of an elastic material [1]. The mentioned ellipse have similar dimension ofbreakdown zone generated in the focal region. It is well known that the residual stressmodify the lattice, and the Raman spectra as well.In this work, we fit the Raman shift for all A1(TO) modes with a threedimensional mechanical deformation which is induced by fs laser interaction forwaveguides fabrication in x-cut Nd3+ doped MgO:LiNbO3 crystals.In order to do that, a numerical model was designed to describe the behaviourof the material as a function of the mechanical deformation. By fitting the A1(TO)Raman spectra for every mode in a line across the waveguides region; for the firsttime, the piezo-spectroscopic constants [2] were determined in this material. It wasconducted taking into account data reported for pure Lithium Niobate crystals underhydrostatic pressure experiments [3].The method presented in this paper, represents an alternative way to find thepiezo-spectroscopic constant for any kind of material, so the refractive index maps canbe inferred from these values therefore suitable fs written waveguides can bedesigned.