| Abstract [eng] |
Electromagnetic radiation pulses of hight intensity propagating in trasparent media can produce a material response with nonlinear polarization with respect to the incident radiation. Such response is the essence of a great many phenomena that affect the properties of the incident wave. This includes generation of harmonic frequencies, multiple wave mixing effects and the changes in material properties, i.e. refractive index, which in turn affects the propagation of light which has created the change. Femtosecond filamentation along with supercontinuum generation are a very dynamical product of an interplay between many such phenomena and generate a coherent broadband ultrashort-pulse radiation for numerous ultrafast applications. We introduce a polycrystalline strontium barium niobate (SBN) as a new medium which even further broadens the variety of nonlinear phenomena for continuum generation as it possesses non-zero quadratic nonlinearity and has a random oriented high aspect ratio domain structure capable of random quasi-phase-matching. In this work a nonlinear refractive index of SBN was measured using two different approaches with the results being comparable between them but lacking in correlation with theoretical model. The supercontinuum spectra produced by femtoseceond filamentation were found to be polarization insensitive and fill a 1-3.5 µm wavelength region. |
