arXiv subjects

Carlo Rizza

Publications and source records attributed to Carlo Rizza.

41 records · Page 3Linked to original sources

arXiv2010

Two-peaked and flat-top perfect bright solitons in epsilon-near-zero nonlinear metamaterials: novel Kerr self-trapping mechanisms

We analytically investigate transverse magnetic (TM) spatial bright solitons, as exact solutions of Maxwell's equations, propagating through nonlinear metamaterials whose linear dielectric permittivity is very close to zero and whose effective nonlinear Kerr parameters can be tailored to achieve values not available in standard materials. Exploiting the fact that, in the considered medium, linear and nonlinear polarization can be comparable at feasible and realistic optical intensities, we identify two novel self-trapping mechanisms able to support two-peaked and flat-top solitons, respectively. Specifically, these two novel mechanisms are based on the occurrence of critical points at which the effective nonlinear permittivity vanishes, the two mechanisms differing in the way the compensation between linear and nonlinear polarization is achieved through the non-standard values of the nonlinear parameters.

physics.optics↗

arXiv2010

Multistability at arbitrary low optical intensities in a metallo-dielectric layered structure

We show that a nonlinear metallo-dielectric layered slab of subwavelength thickness and very small average dielectric permittivity displays optical multistable behavior at arbitrary low optical intensities. This is due to the fact that, in the presence of the small linear permittivity, one of the multiple electromagnetic slab states exists no matter how small is the transmitted optical intensity. We prove that multiple states at ultra-low optical intensities can be reached only by simultaneously operating on the incident optical intensity and incidence angle. By performing full wave simulations, we prove that the predicted phenomenology is feasible and very robust.

physics.optics↗

arXiv2010

Two-parameters electromagnetic hysteresis of a subwavelength nonlinear epsilon-near-zero slab

We consider propagation of transverse magnetic electromagnetic waves through a nonlinear metamaterial slab, of subwavelength thickness and very small average dielectric permittivity, made up of alternating metal and dielectric nonlinear layers. Exploiting the effective-medium approach, we prove that the output field intensity is a multi-valued function of both the input field intensity and incidence angle so that the transmissivity exhibits a novel kind of multi-stability and a pronounced two-parameter hysteresis behavior. The predicted two-parameter hysteresis physically stems from the fact that, since the linear and nonlinear contributions to the overall dielectric response can be comparable, the slab can host more than one electromagnetic configuration compatible with the incident field and the boundary conditions, regardless of the slab thickness. We investigate slab transmission also through full wave simulations proving the robustness of the two-parameter hysteresis beyond the effective-medium approximation.

physics.optics↗

arXiv2010

Transmissivity directional hysteresis of a nonlinear metamaterial slab with very small linear permittivity

We investigate propagation of a transverse magnetic field through a nonlinear metamaterial slab of sub-wavelength thickness and with a very small and negative linear dielectric permittivity. We prove that, for a given input intensity, the output intensity is a multi-valued function of the field incidence angle so that the transmissivity exhibits angular multi-stability and a pronounced directional hysteresis behavior. The predicted directional hysteresis is a consequence of the fact that the linear and nonlinear contributions to the overall dielectric response can be comparable so that the electromagnetic matching conditions at the output slab boundary allow more than one field configurations within the slab to be compatible with the transmitted field.

physics.optics↗

arXiv2008

Tailoring wave nonlinearity through spatial composites

We propose and demonstrate theoretically a method to achieve and design optical nonlinear responses through a light-mediated spatial hybridization of different standard nonlinearities. The mechanism is based on the fact that optical propagation through a spatial composite of different nonlinear media is governed by an effective nonlinear response if the spatial scale of the sequence is much smaller than the light diffraction length. We apply our general approach to the significant case of centrosymmetric photorefractive crystal biased by a periodically modulated external voltage to predict strictly bending-free miniaturized soliton propagation.

physics.optics↗