Nonlinear Properties of "Magnetic Light"

Abstract

Control of light at the nanoscale is demanding for future successful on-chip integration. At the subwavelength scale, the conventional optical elements such as lenses become not functional, and they require conceptually new approach for a design of nanoscale photonic devices. The most common approach to the subwavelength photonics is based on plasmonic nanoparticles and plasmonic waveguides due to their ability to capture and concentrate visible light at subwavelength dimensions. But the main drawback of all plasmonic devices is their intrinsic losses due to metallic components which affect strongly the overall performance of plasmonic structures limiting their scalability and practical use.

Shaping the Radiation Pattern of Second-Harmonic Generation from AlGaAs Dielectric Nanoantennas

“…Moreover, these losses generate Joule heating that could severely hamper the employment of plasmonics for some applications such as surface-enhanced Raman spectroscopy 8,9 . On the other hand, lossless dielectric materials can overcome this problem since their optical losses at visible and nearinfrared wavelengths are negligible 7,10,11 . High-permittivity dielectric nanostructures in a low refractive index background can support strong Mie-type resonances 12 and can thus potentially be employed for nanophotonic applications, which are sensitive to the intrinsic losses and the generated heat, including biosensing, emission control and nonlinear frequency conversion 7,13,14 .…”

“…Importantly, all-dielectric nanostructures offer unique opportunities for the study of nonlinear effects. Due to the very low intrinsic losses, the dielectric nanostructures can sustain much higher optical powers and ultimately provide orders of magnitude higher frequency conversion efficiency 10,22 in comparison to their plasmonic counterparts. In addition, while in plasmonic nanostructures the optical nonlinear response is dominated by surface nonlinearities, enhanced by plasmon resonances at the fundamental and/or at the harmonic wavelengths 3,[23][24][25] , in highpermittivity dielectric nanostructures, the bulk nonlinearity may dominate the optical nonlinear response 26 .…”

“…Thus the overall interaction volume between the incident field and the nanostructure is highly increased, giving rise to better conversion efficiency. Most importantly, the efficiency of nonlinear conversion can be boosted even further by the excitation of multipolar resonant modes of both electric and magnetic nature 10,22,27,28 .…”

“…These advantages have triggered a great interest into the studies of enhanced harmonic generation in resonant dielectric nanoparticles and very promising results have been recently achieved in simple all-dielectric structures 10,22,27,28 targeting applications in biosensing or nonlinear light sources. However, this important development is still in its infancy and there remain two important issues that have to be understood and carefully addressed.…”

“…The first task is to achieve high frequency conversion efficiencies. While the efficiencies of third harmonic generation (THG) of 10 -7 and 10 -6 have been reported 10,29 , which is 4-5 orders of magnitude higher than in plasmonic systems, these still remain low for most practical applications. For example, for biosensing applications efficiencies of the order of 10 -2 -10 -3 will be required in order to outperform the usual fluorescent markers.…”