826 research outputs found
Canonical quantization of macroscopic electrodynamics in a linear, inhomogeneous magneto-electric medium
We present a canonical quantization of macroscopic electrodynamics. The
results apply to inhomogeneous media with a broad class of linear
magneto-electric responses which are consistent with the Kramers-Kronig and
Onsager relations. Through its ability to accommodate strong dispersion and
loss, our theory provides a rigorous foundation for the study of quantum
optical processes in structures incorporating metamaterials, provided these may
be modeled as magneto-electric media. Previous canonical treatments of
dielectric and magneto-dielectric media have expressed the electromagnetic
field operators in either a Green function or mode expansion representation.
Here we present our results in the mode expansion picture with a view to
applications in guided wave and cavity quantum optics.Comment: Submitted to Physical Review A 24/07/201
Coupled-mode theory for periodic side-coupled microcavity and photonic crystal structures
We use a phenomenological Hamiltonian approach to derive a set of coupled
mode equations that describe light propagation in waveguides that are
periodically side-coupled to microcavities. The structure exhibits both Bragg
gap and (polariton like) resonator gap in the dispersion relation. The origin
and physical significance of the two types of gaps are discussed. The
coupled-mode equations derived from the effective field formalism are valid
deep within the Bragg gaps and resonator gaps.Comment: 13 pages, 6 figure
Double-heterostructure cavities: from theory to design
We derive a frequency-domain-based approach for radiation (FAR) from
double-heterostructure cavity (DHC) modes. We use this to compute the quality
factors and radiation patterns of DHC modes. The semi-analytic nature of our
method enables us to provide a general relationship between the radiation
pattern of the cavity and its geometry. We use this to provide general designs
for ultrahigh quality factor DHCs with radiation patterns that are engineered
to emit vertically
Truly unentangled photon pairs without spectral filtering
We demonstrate that an integrated silicon microring resonator is capable of
efficiently producing photon pairs that are completely unentangled; such pairs
are a key component of heralded single photon sources. A dual-channel
interferometric coupling scheme can be used to independently tune the quality
factors associated with the pump and signal and idler modes, yielding a
biphoton wavefunction with Schmidt number arbitrarily close to unity. This will
permit the generation of heralded single photon states with unit purity.Comment: 5 pages, 3 figure
Generation of spin currents via Raman scattering
We show theoretically that stimulated spin flip Raman scattering can be used
to inject spin currents in doped semiconductors with spin split bands. A pure
spin current, where oppositely oriented spins move in opposite directions, can
be injected in zincblende crystals and structures. The calculated spin current
should be detectable by pump-probe optical spectroscopy and anomalous Hall
effect measurement
Does femtosecond time-resolved second-harmonic generation probe electron temperatures at surfaces?
Femtosecond pump-probe second-harmonic generation (SHG) and transient linear
reflectivity measurements were carried out on polycrystalline Cu, Ag and Au in
air to analyze whether the electron temperature affects Fresnel factors or
nonlinear susceptibilities, or both. Sensitivity to electron temperatures was
attained by using photon energies near the interband transition threshold. We
find that the nonlinear susceptibility carries the electron temperature
dependence in case of Ag and Au, while for Cu the dependence is in the Fresnel
factors. This contrasting behavior emphasizes that SHG is not a priori
sensitive to electron dynamics at surfaces or interfaces, notwithstanding its
cause.Comment: 11 pages, 4 figure
Electronic Theory for the Nonlinear Magneto-Optical Response of Transition-Metals at Surfaces and Interfaces: Dependence of the Kerr-Rotation on Polarization and on the Magnetic Easy Axis
We extend our previous study of the polarization dependence of the nonlinear
optical response to the case of magnetic surfaces and buried magnetic
interfaces. We calculate for the longitudinal and polar configuration the
nonlinear magneto-optical Kerr rotation angle. In particular, we show which
tensor elements of the susceptibilities are involved in the enhancement of the
Kerr rotation in nonlinear optics for different configurations and we
demonstrate by a detailed analysis how the direction of the magnetization and
thus the easy axis at surfaces and buried interfaces can be determined from the
polarization dependence of the nonlinear magneto-optical response, since the
nonlinear Kerr rotation is sensitive to the electromagnetic field components
instead of merely the intensities. We also prove from the microscopic treatment
of spin-orbit coupling that there is an intrinsic phase difference of
90 between tensor elements which are even or odd under magnetization
reversal in contrast to linear magneto-optics. Finally, we compare our results
with several experiments on Co/Cu films and on Co/Au and Fe/Cr multilayers. We
conclude that the nonlinear magneto-optical Kerr-effect determines uniquely the
magnetic structure and in particular the magnetic easy axis in films and at
multilayer interfaces.Comment: 23 pages Revtex, preprintstyle, 2 uuencoded figure
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