arXiv subjects

Steffen Kjaer Johansen

Publications and source records attributed to Steffen Kjaer Johansen.

3 recordsLinked to original sources

arXiv2006

Surface waves at the interface between left-handed and birefringent materials

We theoretically investigate the existence and properties of hybrid surface waves forming at interfaces between left-handed materials and dielectric birefringent media. The existence conditions of such waves are found to be highly relaxed in comparison to the original hybrid surface waves, discovered by Dyakonov, in configurations involving birefringent materials and right-handed media. Hybrid surface waves in left-handed materials feature remarkable properties: (i) a high degree of localization and (ii) coexistence of several guided solutions. The existence of several hybrid surface waves for the same parameter set is linked to the birefringent nature of the medium whereas the strong localization is related to the presence of the left-handed material. The hybrid surface modes appear for large areas in the parameter space.

physics.optics↗

arXiv2002

Engineering of spatial solitons in two-period QPM structures

We report on a scheme which might make it practically possible to engineer the effective competing nonlinearities that on average govern the light propagation in quasi-phase-matching (QPM) gratings. Modulation of the QPM period with a second longer period, introduces an extra degree of freedom, which can be used to engineer the effective quadratic and induced cubic nonlinearity. However, in contrast to former work here we use a simple phase-reversal grating for the modulation, which is practically realizable and has already been fabricated. Furthermore, we develop the theory for arbitrary relative lengths of the two periods and we consider the effect on solitons and the bandwidth for their generation. We derive an expression for the bandwidth of multicolor soliton generation in two-period QPM samples and we predict and confirm numerically that the bandwidth is broader in the two-period QPM sample than in homogeneous structures.

nlin.PS↗

arXiv2001

Escape angles in bulk chi(2) soliton interactions

We develop a theory for non-planar interaction between two identical type I spatial solitons propagating at opposite, but arbitrary transverse angles in quadratic nonlinear (or so-called chi(2)) bulk media. We predict quantitatively the outwards escape angle, below which the solitons turn around and collide, and above which they continue to move away from each other. For in-plane interaction the theory allows prediction of the outcome of a collision through the inwards escape angle, i.e. whether the solitons fuse or cross. We find an analytical expression determining the inwards escape angle using Gaussian approximations for the solitons. The theory is verified numerically.

nlin.PS↗