New Crystals for Telecommunications Discovered by Scientists

15:04, July 19, 2018

UrFU researches have studied laser radiation frequency conversion in nonlinear photonic crystals

Physicists of Ural Federal University have studied the optical radiation frequency conversion in nonlinear photonic crystals with hexagonal structure, as reported by Indicator.Ru. The crystals can be used in telecommunication systems. The results of the work have been published in Laser Physics Letters and presented at the International Conference on Luminescence and Laser Physics.

"We have conducted theoretical study of nonlinear optical frequency conversion in a two-dimensional nonlinear photonic crystal with hexagon-shaped domains, that is, elementary units of its structure volume. Instead of one initial beam, the nonlinear structure forms beams that emit under specific angles. Such conversion process can be considered as a nonlinear analog of the Bragg diffraction, a type of waves scattering on a system of periodically ordered elements", says one of the authors Andrey Viunyshev, Candidate of Physical and Mathematical Sciences, Senior Researcher at the Laboratory of Coherent Optics, Kiriensky Institute of Physics, Siberian Division of the Russian Academy of Sciences.

The integrated research was performed by theorists, technologists and experimenters. As a sample of the nonlinear photonic crystal, the physicists took a ferroelectric crystal of lithium neobate, a crystal with spontaneous polarization, the direction of which can be measured by external electric field. The study sample contained hexagon-shaped domains, ordered in the sample volume. The authors measured the radiation intensity distribution on a certain wavelength. The developed theoretical model allowed to predict the key characteristics of the converted radiation with high degree of accuracy.

The scientists are planning to optimize the parameters of the structure in order to increase the conversion efficiency. Also, with the help of such structures, they want to perform optical parametric interactions. This could find its use in nonlinear optical converters, which can change the frequency and spatial structure of the radiation, making it multibeam. Currently, only single-beam optical frequency converters are used.

"The transition to two-dimensional nonlinear optical structures will allow to simultaneously generate a series of light beams, which is of interest in terms of development of multichannel analogs of integrated converters for use in telecommunications and photolithography. Moreover, nonlinear optical processes are sources of nonclassical light fields, which is why they are of significant interest for quantum information", concludes Andrey Viunyshev.

The research was performed by the staff of Kiriensky Institute of Physics (Siberian Division of the RAS), Lomonosov Moscow State University, Siberian Federal University and Ural Federal University.

• Multiple nonlinear Bragg diffraction of femtosecond laser pulses in a photonic lattice with hexagonal domains