Use of quasi-local photorefractive response to generated superficial self-written waveguides in lithium niobate

Abstract

We report the formation of surface self-written waveguides by means of surface pyrolitons in lithium niobate. By a specific orientation of the crystal axis the quasi-local slow photorefractive response of lithium niobate was used to induce a self-confined beam exactly at the crystal-air interface. The mode profile of the photo-induced waveguide is strongly asymmetric due to the interface presence.

Anisotropic build-up of photo-induced waveguides in biased photorefractive media

“…Reconfigurable or semi-permanent optical waveguides can be realized by means of the photoinduced refractive index changes arising from the photorefractive (PR) effect either in a longitudinal [1,2,3], or a lateral illumination configuration of an appropriate biased crystal [4,5,6,7]. The former technique is based on the self-focusing mechanism of the recording light and leads to waveguides, which are essentially straight or only slightly bended.…”

Design of a refractive index sensor based on surface soliton waveguides

“…Due to the nonlocality of the photorefractivity (which is directly correlated with the photo-excited electric current) surface solitons do not touch the interface with air, but lie a few microns below it without touching it [31]. However, very recently pure superficial photorefractive waveguides have been experimentally demonstrated [32]. With respect to traditional dielectric waveguides, soliton ones have much lower propagation losses and usually self-align, realizing final complex structures self-optimized for light propagation.…”