We analize the dipole spectrum of a two-level atom excited by a non-resonant intense monochromatic field, under the electric dipole approximation and beyond the rotating wave approximation. We show that the apparently complex spectral structure can be completely described by two families: harmonic frequencies of the driving field and field-induced nonlinear fluorescence. Our formulation of the problem provides quantitative laws for the most relevant spectral features: harmonic ratios and phases, non-perturbative Stark shift, and frequency limits of the harmonic plateau. In particular, we demonstrate the locking of the harmonic phases at the wings of the plateau opening the possibility of ultra-short pulse generation through harmonic filtering.
We study the fluctuation-mediated interactions between two atoms in the presence of an aplanatic lens, demonstrating an enhancement in their resonant dipole-dipole interaction. We derive the field propagation of the linear optical system in terms of the electromagnetic Green's tensor for an aplanatic lens. The collective internal atomic dynamics is analyzed via a Lindblad master equation, which allows one to characterize the dispersive and dissipative interactions between atoms. We thus demonstrate that the resonant dipole-dipole coupling between the atoms can be enhanced in the focal plane of…
We present an experimental and theoretical energy- and angle-resolved study on the photoionization dynamics of non-resonant one-color two-photon single valence ionization of neutral N$_2$ molecules. Using 9.3 eV photons produced via high harmonic generation and a 3-D momentum imaging spectrometer, we detect the photoelectrons and ions produced from one-color two-photon ionization in coincidence. Photoionization of N$_2$ populates the X $^2Σ^+_g$, A $^2Π_u$, and B $^2Σ^+_u$ ionic states of N$_2^+$, where the photoelectron angular distributions associated with the X $^2Σ^+_g$ and A $^2Π_u$ state…
We consider the resonant Casimir-Polder interaction of an excited alkali-type atom which has a single (electric dipole) transition with a Chern insulator. The Chern insulator has a nonzero, time reversal symmetry breaking Hall conductance, leading to an additional contribution to the resonant Casimir-Polder interaction which depends on the coupling between the Hall conductance and the circular polarization state of the atomic transition. We find that the resonant Casimir-Polder shift can be significantly enhanced for de-excitation frequencies near values associated with the van Hove singularit…
Strong light interaction with a subwavelength object has been a long pursuing goal with difficulties mainly arising from the diffraction limit. We propose a high finesse cavity with one mirror made of a subwavelength resonant particle as a platform to enhance this interaction. High-quality eigenmode solutions are obtained for such a highly non-paraxial cavity with a very high field concentration at the particle. The eigenmode solutions interact with the small particle in a more general way than by the electric dipole approximation. With the help of the anapole excitation in the dipole term, th…
Dipole-quadrupole model and multipole analysis of resonant membrane metasurfaces
Leibniz University Hannover（汉诺威莱布尼茨大学）；Hannover Centre for Optical Technologies, Leibniz University Hannover（汉诺威光学技术中心，汉诺威莱布尼茨大学）；Institute of Transport and Automation Technology, Leibniz University Hannover（交通与自动化技术研究所，汉诺威莱布尼茨大学）；Cluster of Excellence PhoenixD, Leibniz University Hannover（PhoenixD卓越集群，汉诺威莱布尼茨大学）；Institute of Quantum Optics, Leibniz University Hannover（量子光学研究所，汉诺威莱布尼茨大学）
The analytical solutions for the general-four-wave-mixing hyperpolarizabilities $χ^{(3)}(-(w_1+w_2+w_3);w_1,w_2,w_3)$ on infinite chains under both Su-Shrieffer-Heeger and Takayama-Lin-Liu-Maki models of trans-polyacetylene are obtained through the scheme of dipole-dipole correlation. Analytical expressions of DC Kerr effect $χ^{(3)}(-w;0,0,w)$, DC-induced second harmonic generation $χ^{(3)}(-2w;0,w,w)$, optical Kerr effect $χ^{(3)}(-w;w,-w,w)$ and DC-electric-field-induced optical rectification $χ^{(3)}(0;w,-w,0)$ are derived. By including or excluding ${\bf \nabla_k}$ terms in the calculatio…
Recently a hypothesis explaining the non-resonant mechanism of subwavelength imaging granted by a dielectric microsphere has been suggested. In accordance to the hypothesis, the far-field image of a subwavelength scatterer strongly coupled to a microsphere by near fields is offered by the scatterer polarization normal to the sphere surface. The radiation of a closely located normally oriented dipole is shaped by the microsphere so that the transmitted wave beam has a practically flat phase front. Then this beam turns out to be imaging -- keeping the subwavelength information about the dipole l…
Resonant lattice Kerker effect in periodic resonators is one of the most interesting generalizations of the Kerker effect that relates to various fascinating functionalities such as scattering management and Huygens metasurfaces. However, so far this effect has been shown to be sensitive to the incident polarization, restricting its applications. Here, we report, for the first time, polarization-independent resonant lattice Kerker effect in metasurfaces composed of periodic Ge$_2$Se$_2$Te$_5$ (GST) disks. For such a metasurface of square lattice, the spectrally overlap of the electric dipole a…
