High-energy few-cycle pulses in the mid-IR are important for applications in strong-field physics. A popular method to generate such pulses is spectral broadening of ultrashort pulses by means of self-phase modulation (SPM) in a nonlinear medium with subsequent post-compression. This is an established technique in the near infrared by employing hollow-core fibers (HCF) [1], thin plates or multi-pass cells, but there are no studies for wavelengths longer than 4 μm. Here, we report self-compression of pulses at 5-μm wavelength in a HCF due to solitonic effects. A numerical model is established for the pulse propagation and is benchmarked against the experimental results.

We experimentally and numerically investigate self-compression of pulses around 5μm wavelength in a noble-gas-filled hollow waveguides. We demonstrate spectral broadening of multi-mJ pulses at 4.9μm and associated pulse compression from 85 fs to 47 fs in the solitonic pulse compression regime. The self-compression resulted in sub-three-cycle pulses with 17 GW peak power in the 1-kHz pulse train. A numerical model is established and benchmarked against the experimental results. It allows further insights into the pulse compression process, such as scaling of the compression as a function of gas pressure and waveguide radius, and predicts pulse compression in sub-cycle regime for realistic input parameters.

In the present paper we study the influence of the Coulomb potential on the real and imaginary parts of the plasma-induced susceptibility in a photoionized gas. We show that the real part of the susceptibility is more than one order of magnitude larger due to the action of a Coulomb potential. Surprisingly, the long-range Coulomb potential of the atomic core leads to an additional contribution to the imaginary part of the susceptibility which has no counterpart in the case of a short-range potential. We demonstrate that the origin of this behavior are electrons in states very close to the continuum (nearly-free electrons), and analyze the dependence of the susceptibility on the intensity and wavelengths.

In this letter, we follow the hypothesis that the tangent bundle (TB) with the central extended little groups of the SO(3, 1)⋊T(1, 3) group as gauge group is the underlying geometric structure for a unified theory of the fundamental physical interactions. Based on the geometry of the TB, recently, I presented a generalized theory of electroweak interaction in [1]. The vertical (internal) Laplacian of the tangent bundle possesses the same form as the Hamiltonian of a 2D semiconductor quantum Hall system. The three families of leptons and quarks, unlike in the SM, are distinguished by a new quantum number. Here, it will be shown that the SU(3) color symmetry for strong interaction arises as an emergent symmetry similar to Chern- Simon gauge symmetries in multicomponent quantum Hall systems and fractional charge quantization of quarks can be understood by a binding of two vortices to a quark, turning it into a composite quark. The analogy with the anomalous quantum Hall effect could hint at the possible existence of exotic quark states with a hypercharge of e/5. Note that based on translational transformations in the TB geometry previously a gauge theoretical understanding of gravity has been achieved. Therefore, the TB can be considered as the underlying geometry that could constitute a possible way for the unification of the known fundamental forces.

The optical properties of metallic nanoparticles are most often considered in terms of plasmons, the coupled states of light and quasifree electrons. Confinement of electrons inside the nanostructure leads to another, very different type of resonances. We demonstrate that these confinement-induced resonances typically join into a single composite "super-resonance," located at significantly lower frequencies than the plasmonic resonance. This super-resonance influences the optical properties in the low-frequency range, in particular, producing giant nonlinearities. We show that such nonlinearities can be used for efficient down-conversion from optical to terahertz and midinfrared frequencies on the submicrometer propagation distances in nanocomposites. We discuss the interaction of the quantum-confinement-induced super-resonance with the conventional plasmonic ones, as well as the unusual quantum level statistics, adapting here the paradigms of the quantum billiard theory and showing the possibility to control the resonance position and width using the geometry of the nanostructures.

This paper pursues the hypothesis that the tangent bundle (TB) with the central extended little groups of the SO(3,1) group as gauge group is the underlying geometric structure for a unified theory of the fundamental physical interactions. Based on this hypothesis as a first step, I recently presented a generalized theory of electroweak interaction (including hypothetical dark matter particles) (Herrmann in Eur Phys J C 79:779, 2019). The vertical Laplacian of the tangent bundle possesses the same form as the Hamiltonian of a 2D semiconductor quantum Hall system. This explains fractional charge quantization of quarks and the existence of lepton and quark families. As will be shown, the SU(3) color symmetry for strong interactions arises in the TB as an emergent symmetry similar to Chern–Simon gauge symmetries in quantum Hall systems. This predicts a signature of quark confinement as a universal large-scale property of the Chern–Simon fields and induces a new understanding of the vacuum as the ground state occupied by a condensate of quark–antiquark pairs. The gap for quark–antiquark pairing is calculated in the mean-field approximation, which allows a numerical estimation of the characteristic parameters of the vacuum such as its chemical potential, the quark condensation parameter and the vacuum energy. Note that a gauge theoretical understanding of gravity was previously achieved by considering the translation group T(3,1) in the TB as gauge group. Therefore, the theory presented here can be considered as a new type of unified theory for all known fundamental interactions linked with the geometrization program of physics.

As it is known, metallic nanostructures demonstrate strong nonlinearities [1] . Despite of strong losses inherent for metals, this allows for nonlinear optics, for instance, second and third harmonic generation [2] , [3] , downcon-version [2] , promising for various applications such as supercontinuum generation [4] . Since the losses in metals increase with wavelength, using metallic nanostructures for generation of low frequency fields in, e.g. mid-infrared (MIR) or terahertz (THz) range were barely considered up to now.

The waveguide-coupled plasmonic nanocavity is known to be a deep subwavelength platform that combines on-chip compatibility with a strong light-matter interaction at the resonance of local field enhancement; however, the resonant local field enhancement provides no magneto-optical activity. We conceptually investigate the deep subwavelength flow-resonant modes of the waveguide-coupled plasmonic nanocavity at which the local field enhancement deviates from the strongest and, instead, the power flow reaches its maximum. These flow-resonant modes exhibit resonant enhancements of magneto-optical activity and the inverse Faraday effect. Frequency-selective enhancement of light-magnetization interaction at the flow-resonant modes allows us to propose multichannel all-optical writing and reading of magnetic bits in nanophotonic integrated circuits. Our findings would open the way towards on-chip deep subwavelength magneto-optical devices and opto-magnetic recording with a great potential for high-speed on-chip memory.

In this Rapid Communication, we study the generation of quasistatic magnetic fields by the plasmon-induced inverse Faraday effect and present analytical and numerical results for the computation of the induced magnetic field distributions in magnetoplasmonic waveguides. We show that the magnetization of a magnetic area can be reversed within sub-picosecond time in nanoconfined magnetoplasmonic waveguides by surface plasmon polaritions (SPP) and the magnetization can be switched back by a SPP propagating into the opposite direction. In addition, we study a magneto-optical dielectric cavity side coupled to a metal-insulator-metal (MIM) waveguide and show that magnetization switching can be implemented in this structure by SPPs generated by two-frequency pulses as well as by counterpropagating SPPs. These phenomena could open up a new energy-efficient ultrafast method for nanoconfined all-optical magnetization switching.

AbstractA generalized theory of electroweak interaction is developed based on the underlying geometrical structure of the tangent bundle with symmetries arising from transformations of tangent vectors along the fiber axis at a fixed spacetime point given by the SO(3,1) group. Electroweak interaction beyond the standard model (SM) is described by the little groups$$ SU(2)\otimes E^{c}(2)$$SU(2)⊗Ec(2)($$E^{c}(2)$$Ec(2)is the central extended Euclidian group) which includes the group$$SU(2)\otimes U(1)$$SU(2)⊗U(1)as a limit case. In addition to isospin and hypercharge, two additional quantum numbers arise which explain the existence of families in the SM. The connection coefficients yield the SM gauge potentials but also hypothetical gauge bosons and other hypothetical particles as a Higgs family as well as candidate Dark Matter particles are predicted. Several important consequences for the interaction between dark fermions, dark scalars or dark vector gauge bosons with each other and with SM Higgs and Z-bosons are described.

In this paper we study an approach for nanoscale spatially inhomogeneous excitation of quasistatic magnetic fields by the plasmon-induced inverse Faraday effect (IFE) in graphene-covered semiconductors and we present analytical and numerical results for the induced magnetic field distribution. The effective magnetic field is predicted to reach about 1 T and the direction of the magnetic field can be switched by surface plasmon polaritons propagating into the opposite direction. By electrically controlling the chemical potential of the graphene sheet the spatial inhomogeneity of the magnetization near field can be broadly tuned. The response of the induced magnetization to the plasmon propagation is manifested by a nonlinear phase shift which is measurable in the far field. By using the Lorentz reciprocity theorem we analytically calculated the nonlinear susceptibility and the nonlinear absorption coefficient in dependence on the chemical potential, the frequency, and the other material parameters. The plasmon-induced IFE and the nonlinearity can be very strong by decreasing the chemical potential which is flexibly controllable by using the graphene's gate voltage. The studied system could pave the way for an alternative approach for nanometer spatial all-optical magnetization control.

Nanoscale optical isolators are crucial for nanophotonic, quantum-optical, and optoelectronic applications and have attracted considerable attention recently. The application of external magnetic fields is the standard way for creating nonreciprocity as the basis for optical isolation. However, the magneto-optical response is usually small, thus it should be enhanced to create strong enough nonreciprocity for high-contrast isolation. We demonstrate that a graphene waveguide ring resonator allows a nanoscale platform for a high-contrast optical isolator. Graphene provides strong subwavelength confinement and low loss, therefore large nonreciprocity can be realized for ultracompact high-contrast isolators by plasmon resonance enhancement combined with resonator resonance enhancement. The resonance frequency is widely tunable by controlling the gate voltages of the rolling graphene sheet of a graphene resonator. Manipulation of the waveguide-resonator coupling can be achieved by controlling the gate voltage of the planar graphene sheet. The concept of magnetically biased ultracompact graphene waveguide ring resonators for one-way plasmon flow allows one to tune the operation band over a one-octave-spanning broad frequency range, keeping the contrast higher than 99% and a moderate insertion loss lower than 50%. High performance is achievable by only adjusting both gate voltages of the planar and rolling graphene sheets.

We analytically and numerically investigate magneto-plasmons in metal films surrounded by a ferromagnetic dielectric. In such waveguide using a metal film with a thickness exceeding the Skin depth, an external magnetic field in the transverse direction can induce a significant spatial asymmetry of mode distribution. Superposition of the odd and the even asymmetric modes over a distance leads to a concentration of the energy on one interface which is switched to the other interface by the magnetic field reversal. The requested magnitude of magnetization is exponentially reduced with the increase of the metal film thickness. Based on this phenomenon, we propose a waveguide-integrated magnetically controlled switchable plasmonic routers with 99-%-high contrast within the optical bandwidth of tens of THz. This configuration can also operate as a magneto-plasmonic modulator.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text C. Ri, S. Im, J. Pae, K. Ho, and J. Herrmann, "Third-order nonlinearity by the plasmon-induced inverse Faraday effect," in Light, Energy and the Environment 2018 (E2, FTS, HISE, SOLAR, SSL), OSA Technical Digest (Optica Publishing Group, 2018), paper SW2D.3. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

Here we propose and study a novel type of plasmonic resonators based on a metal-insulator-metal waveguide and a side-coupled magneto-optical disk controlled by an external magnetic field. The wave-number change and the transmission of surface-plasmon-polaritons (SPPs) can be tuned by altering the magnetic field and reversible on/off switching of the running SPP modes by a reversal of the direction of the external magnetic field is demonstrated. Resonant enhancement of the magnetoplasmonic modulation by more than 200 times leads to a modulation contrast ratio more than tenfold ratio (90-% modulation) keeping a moderate insertion loss within an optical bandwidth of hundreds of GHz. Numerical simulations confirm the predictions by the derived analytical formulas of a high-contrast magnetoplasmonic modulation by the submicrometer ultrasmall disk resonator.

We present a theoretical method for the calculation of the transient nonlinearity in dielec- tric composites doped with metal nanoparticles and demonstrate some applications of this approach. First, we describe the theoretical basis of the linear and nonlinear properties of metal nanoparticles by using the time-domain discrete-dipole approximation. By using the two-temperature model for the description of the electron-electron and electron-lattice interaction, we derive an equation for the transient third-order nonlinear susceptibility. Based on this method and the effective medium approximation, we present numerical results for the nonlinear optical susceptibility for different nanocomposites media consisting of noble metal nanoparticles surrounded by a dielectric host. With increasing pump intensities, the plasmon resonance is shifted which leads to a saturation of the absorption. We present a theory of mode-locking of solid-state and semiconductor disk lasers using metal nanocomposites as saturable absorbers. Finally, we consider a novel slow-light device based on metal nanocomposites.

We theoretically investigated the magnetically-tunable cutoff of long-range surface plasmon polariton along thin metal film surrounded by a magneto-optic material on one side and by a nonmagnetic dielectric on the other side. The analytically derived cutoff condition predicts that a magnetic field bias can induce a novel degenerate cutoff-state near which the beyond-cutoff radiation in one side can be switched to that in the other side by a minor variation of the magnetic field from the bias. The magnetization bias needed for the degeneracy is in proportion to the metal film thickness and in inverse proportion to the wavelength.

We predict a different type of ultrafast third-order nonlinearity of surface plasmon polaritons (SPPs) in planar magnetoplasmonic structures caused by the inverse Faraday effect (IFE). Planar SPPs with a significant longitudinal component of the electric field act via the IFE as an effective transverse magnetic field. Its response to the plasmon propagation leads to strong ultrafast self-action which manifests itself through a third-order nonlinearity. We derive a general formula and analytical expressions for the IFE-related nonlinear susceptibility for two specific planar magnetoplasmonic structures from the Lorentz reciprocity theorem. Our estimations predict a very large nonlinear third-order nonlinear susceptibility exceeding those of typical metals such as gold.

We investigate the nonlinear propagation of surface plasmon polaritons guided on gold nanowires surrounded by silica glass. Based on the Lorentz reciprocity theorem, we derive a formula for the complex nonlinear susceptibility, and study its dependence on waveguide parameters and wavelength for the fundamental mode. Depending on these parameters both positive and negative signs of the real and imaginary parts of the nonlinear coefficient are predicted. This implies that nanowires exhibit the property of saturable absorption or optical limiting as well as positive and negative nonlinear phase shifts. The physical origin of this phenomenon is discussed.