arXiv subjects

Alexander Kuhlicke

Publications and source records attributed to Alexander Kuhlicke.

3 recordsLinked to original sources

arXiv2017

'Flying Plasmons': Fabry-Pèrot Resonances in Levitated Silver Nanowires

Plasmonic nano structures such as wire waveguides or antennas are key building blocks for novel highly integrated photonics. A quantitative understanding of the optical material properties of individual structures on the nanoscale is thus indispensable for predicting and designing the functionality of complex composite elements. In this letter we study propagating surface plasmon polaritons in single silver nanowires isolated from its environment by levitation in a linear Paul trap. Symmetry-breaking effects, e.g., from supporting substrates are completely eliminated in this way. Illuminated with white light from a supercontinuum source, Fabry-Pèrot-like resonances are observed in the scattering spectra obtained from the ends of the nanowires. The plasmonic nature of the signal is verified by local excitation and photon collection corresponding to a clean transmission measurement through a Fabry-Pèrot resonator. A numerical simulation is used to compute the complex effective refractive indices of the nanowires as input parameter for a simple Fabry-Pèrot model, which nicely reproduces the measured spectra despite the highly dispersive nature of the system. Our studies pave the way for quantitative characterization of nearly any trappable plasmonic nano object, even of fragile ones such as droplets of liquids or molten metal and of nearly any nanoresonator based on a finite waveguide with implications for modeling of complex hybrid structures featuring strong coupling or lasing. Moreover, the configuration has the potential to be complemented by gas sensors to study the impact of hot electrons on catalytic reactions nearby plasmonic particles.

physics.optics↗

arXiv2016

Limitations of Particle-Based Spasers

We present a semi-classical analytic model for spherical core-shell surface plasmon lasers. Within this model, we drop the widely used one-mode approximations in favor of fully electromagnetic Mie theory. This allows for incorporation of realistic gain relaxation rates that so far have been massively underestimated. Especially, higher order modes can undermine and even reverse the beneficial effects of the strong Purcell effect in such systems. Our model gives a clear view on gain- and resonator-requirements, as well as on the output characteristics that will help experimenters to design more efficient particle-based spasers.

physics.optics↗

arXiv2014

A fully nanoscopic dielectric laser

In this article, we introduce the concept of a dielectric nanolaser that is nanoscopic in all spatial dimensions. Our proposal is based on dielectric nanoparticles of high refractive index, e.g., silicon, acting as a (passive) cavity (without intrinsic gain) that is decorated with a thin film of organic gain media. Its resonance frequencies can be tuned over the entire visible range and bright and dark modes can be addressed. So called "magnetic" modes can be utilized, which makes this dielectric nanolaser a complementary source of coherent nearfields similar to the surface plasmon laser (which exploits electric modes). The small intrinsic losses in silicon yield relatively high quality factors and low non-radiative decay rates of emitters close to the cavity, both of which will lead to low thresholds. As we show in this work, the dielectric nanolaser exhibits certain advantages relative to nanowire lasers and spasers, such as reduced laser threshold, short switch-on times, size and design flexibility. The dielectric nanolaser is compatible with standard lithographic fabrication approaches and its relative simple design may allow for easy testing and realization of the concept. Thus, the silicon nanolaser might soon find many applications in nanooptics and metamaterials.

physics.optics↗