1,530 research outputs found
Micro-joule sub-10-fs VUV pulse generation by MW pump pulse using highly efficient chirped-four-wave mixing in hollow-core photonic crystal fibers
We theoretically study chirped four-wave mixing for VUV pulse generation in
hollow-core photonic crystal fibers. We predict the generation of sub-10-fs VUV
pulses with energy of up to hundreds of microjoule by broad-band chirped idler
pulses at 830 nm and MW pump pulses with narrow-band at 277 nm. MW pump could
be desirable to reduce the complexity of the laser system or use a high
repetition rate-laser system. The energy conversion efficiency from pump pulse
to VUV pulse reaches to 30%. This generation can be realized in kagome-lattice
hollow-core PCF filled with noble gas of high pressure with core-diameter less
than 40 micrometers which would enable technically simple or highly efficient
coupling to fundamental mode of the fiber
Plasmonic amplification and suppression in nanowaveguide coupled to gain-assisted high-quality plasmon resonances
We theoretically study transmission in nanowaveguide coupled to high-quality
plasmon resonances for which the metal loss is overcompensated by gain. The
on-resonance transmission can vary widely from lower than --20dB to higher than
20dB for a range of gain coefficient. A reversible transition between the
high-quality amplification and the suppression can be induced by a quite small
change of gain coefficient for a moderately increased distance between the
waveguide and the resonator. It is expected that in practice a small change of
gain coefficient can be made by flexibly controlling pumping rate or utilizing
nonlinear gain. Additionally, based on the frequency-dependant model for
gain-transition susceptibility, it is shown that the wide variation of the
on-resonance transmission can also be observed for defferent detuning of the
gain-transition line-center. Such a widely controllable on-resonance
transmission is promising for applications such as well-controlled lumped
amplification of surface plasmon-polariton as well as plasmonic switching.Comment: submitted to Laser Physics Letter
Intrinsic nonlinear response of surface plasmon polaritons
We offer a model to describe the intrinsic nonlinear response of surface
plasmon polaritons (SPPs). Relation of the complex nonlinear coefficient of
SPPs to the third-order nonlinear susceptibility of the metal is provided. As
reported in a recent study, gold is highly lossy and simultaneously highly
nonlinear due to interband absorption and interband thermo-modulation at a
wavelength shorter than 700 nm. The effect of the high loss of the metal on the
SPP nonlinear propagation is taken into account in our model. With the model we
show difference in sign of real and imaginary parts between the nonlinear
propagation coefficient and the nonlinear susceptibility of component material
for the first time to our knowledge. Our model could have practical importance
in studying plasmonic devices utilizing the nonlinear phase modulation and the
nonlinear absorption of SPPs. For example, it allows one to extract the complex
nonlinear susceptibility of gold through a measurement of SPP nonlinear
propagation at the visible range
Generating Functional in String Field Theory
In our paper, we introduce a path integral of general functional field in
order to build the path integral formalism in string field theory from the fact
that a string field is a functional field, and describe a method for
calculating it in the case of "Gauss-type". We also obtain the generating
functional of an open bosonic string and the corresponding Feynman diagram
Third-order nonlinearity by the inverse Faraday effect in planar magnetoplasmonic structures
We predict a new type of ultrafast third-order nonlinearity of surface
plasmon polaritons (SPP) in planar magneto-plasmonic 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 magneto-plasmonic
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
Mechanism of the Fano resonance in a planar metamaterials: Analysis from the coupled two-oscillator model
Mechanism of the Fano resonances in planar metamaterials demonstrate based on
the coupled two-oscillator model. We have described the optical spectrums like
reflectance and transmittance near the resonances of bright mode (continuum
mode) and dark mode (discrete mode) and explained their optical properties by
the Fano formulism. the Fano formulism of the resonances in the planar
metamaterials can predict the asymmetric shape line and radiative properties
occurring in reflectance and transmittance from the coupling between bright and
dark modes
Effect of exchange interaction on electronic instabilities in the honeycomb lattice: A functional renormalization group study
The impact of local and nonlocal density-density interactions on the
electronic instabilities in the honeycomb lattice is widely investigated. Some
early studies proposed the emergence of interaction-induced topologically
nontrivial phases, but recently, it was denied in several works including
renormalization group calculations with refined momentum resolution. We use the
truncated unity functional renormalization group to study the many-body
instabilities of electrons on the half-filled honeycomb lattice, focusing on
the effect of the exchange interaction. We show that varying the
next-nearest-neighbor repulsion and nearest-neighbor exchange integral can lead
to diverse ordered phases, namely, the quantum spin Hall, the spin-Kekul\'e,
and some spin- and charge-density-wave phases. The quantum spin Hall phase can
be induced by a combination of the ferromagnetic exchange and pair hopping
interactions. Another exotic phase, the spin-Kekul\'e phase, develops in a very
small region of the parameter space considered. We encounter the
three-sublattice charge-density-wave phase in a large part of the parameter
space. It is replaced by the incommensurate charge density wave when increasing
the exchange integral. In order to reduce the computational effort, we derive
the explicit symmetry relations for the bosonic propagators of the effective
interaction and propose a linear-response-based approach for identifying the
form factor of order parameter. Their efficiencies are confirmed by numerical
calculations in our work.Comment: 13 pages, 6 figures, 1 Tabl
Theoretical prediction of the source-detector separation distance suited to the application of the spatially resolved spectroscopy from the near-infrared attenuation data cube of tissues
The modified Beer-Lambert law (MBL) and the spatially resolved spectroscopy
are used to measure the tissue oxidation in muscles and brains by the
continuous wave near-infrared spectroscopy. The spatially resolved spectroscopy
predicts the change in the concentration of the absorber by measuring the slope
of attenuation data according to the separation and calculating the absorption
coefficients of tissue on the basis of the slop in attenuation at the
separation distance satisfying the linearity of this slop. This study analyzed
the appropriate source-detector separation distance by using the diffuse
approximation resolution for photon migration when predicting the absorption
coefficient by the spatially resolved spectroscopy on the basis of the
reflective image of the tissue. We imagine the 3 dimensional attenuation image
with the absorption coefficient, reduced scattering coefficient and separation
distance as its axes and obtained the attenuation data cube by calculating the
attenuation on a certain interval of coordinate on the basis of the diffuse
approximation expression. We predicted the separation distance appropriate for
the application of the spatially resolved spectroscopy by calculating and
analyzing the first derivatives and second derivatives of attenuation with
respect to the coordinates and also doing the differential pathlength factors
and first derivatives of the attenuation with respect to the absorption
coefficient from the attenuation data cube. When analyzing the hemoglobin
derivatives in tissues, the appropriate separation distances are 3-5cm and the
value of its corresponding differential pathlength factors are from 3.5 to 5.
These data agree with the preceding experimental data
Study on the Thickness Change of Nickel-Plated Layer in Fabrication of the Silver Hollow Nickel Waveguides by the Outer-Coating Method of the Liquid Phase Process
A metallic hollow waveguide is promising fiber for the delivery of laser
radiation. Thickness of the nickel plated layer for supporting of the waveguide
in fabrication of a dielectric coated silver hollow nickel waveguide is very
important factor. In this paper, the change characteristic in the thickness of
the nickel plated layer along the length of the silver coated glass mandrel
during fabricating the silver hollow nickel waveguide by the outer-coating
method of the liquid phase process has been studied both experimentally and
analytically. Waveguides with uniform thickness of the nickel plated layer
along the length of the silver coated glass mandrel have been fabricated
Classical Equation of Electromagnetic Field in the Higgs Boson Field and Estimation on the Static Electrical Polarizability of Leptons
In our paper we derived the classical motion equation of electromagnetic
field in space with Higgs field and by means of it discussed the distributions
of charge and current formed when the static electrical and magnetic fields are
interacting with the spherically symmetrical Higgs field, and predicted the
electrical polarizability of electron
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