124 research outputs found
Tailoring second-harmonic generation in birefringent poled fiber via Twist
We predict theoretically and demonstrate experimentally the ability to generate and control the strengths of various second-harmonic signals in birefringent poled fiber. This is done by simply twisting the fiber
First-principles method for high- photonic crystal cavity mode calculations
We present a first-principles method to compute radiation properties of
ultra-high quality factor photonic crystal cavities. Our Frequency-domain
Approach for Radiation (FAR) can compute the far-field radiation pattern and
quality factor of cavity modes times more rapidly than conventional
finite-difference time domain calculations. It also provides a simple rule for
engineering the cavity's far-field radiation pattern
Broadband polarization-entanglement in a poled fiber
Broadband polarization-entanglement over 100 nm is demonstrated in a poled fiber phase-matched for type-II downconversion in the 1.5µm telecom-band. Two-photon interference and Hong-Ou-Mandel interference are used experimentally to confirm the broadband nature of the entanglement
Quantum wave equation of photon
In this paper, we give the quantum wave equations of single photon when it is
in the free or medium space. With these equations, we can study light
interference and diffraction with quantum approach. Otherwise, they can be
applied in quantum optics and photonic crystal.Comment: 8 pages, 0 figure
Ultrafast extrinsic spin-Hall currents
We consider the possibility of ultrafast extrinsic spin-Hall currents,
generated by skew scattering following the optical injection of charge or pure
spin currents. We propose a phenomenological model for this effect in quantum
well structures. An injected charge current leads to a spin-Hall-induced pure
spin current, and an injected pure spin current leads to a spin-Hall-induced
charge current. The resulting spin or charge accumulation can be measured
optically.Comment: 18 pages, 3 figure
Optical cavity implementations of the quantum walk
We discuss how the coined quantum walk on the line or on the circle can be
implemented using optical waves. We propose several optical cavity
configurations for these implementations.Comment: Revised version to appear in Optics Communications. Important changes
concerning: (i) technical details, (ii) the analysis of the experiment of
Bouwmeester et al., and (iii) the conclussion section, which is entirely ne
Second harmonic generation and birefringence of some ternary pnictide semiconductors
A first-principles study of the birefringence and the frequency dependent
second harmonic generation (SHG) coefficients of the ternary pnictide
semiconductors with formula ABC (A = Zn, Cd; B = Si, Ge; C = As, P) with
the chalcopyrite structures was carried out. We show that a simple empirical
observation that a smaller value of the gap is correlated with larger value of
SHG is qualitatively true. However, simple inverse power scaling laws between
gaps and SHG were not found. Instead, the real value of the nonlinear response
is a result of a very delicate balance between different intraband and
interband terms.Comment: 13 pages, 12 figure
Second Harmonic Generation for a Dilute Suspension of Coated Particles
We derive an expression for the effective second-harmonic coefficient of a
dilute suspension of coated spherical particles. It is assumed that the coating
material, but not the core or the host, has a nonlinear susceptibility for
second-harmonic generation (SHG). The resulting compact expression shows the
various factors affecting the effective SHG coefficient. The effective SHG per
unit volume of nonlinear coating material is found to be greatly enhanced at
certain frequencies, corresponding to the surface plasmon resonance of the
coated particles. Similar expression is also derived for a dilute suspension of
coated discs. For coating materials with third-harmonic (THG) coefficient,
results for the effective THG coefficients are given for the cases of coated
particles and coated discs.Comment: 11 pages, 3 figures; accepted for publication in Phys. Rev.
Effective nonlinear optical properties of composite media of graded spherical particles
We have developed a nonlinear differential effective dipole approximation
(NDEDA), in an attempt to investigate the effective linear and third-order
nonlinear susceptibility of composite media in which graded spherical
inclusions with weak nonlinearity are randomly embedded in a linear host
medium. Alternatively, based on a first-principles approach, we derived exactly
the linear local field inside the graded particles having power-law dielectric
gradation profiles. As a result, we obtain also the effective linear dielectric
constant and third-order nonlinear susceptibility. Excellent agreement between
the two methods is numerically demonstrated. As an application, we apply the
NDEDA to investigate the surface plasma resonant effect on the optical
absorption, optical nonlinearity enhancement, and figure of merit of
metal-dielectric composites. It is found that the presence of gradation in
metal particles yields a broad resonant band in the optical region, and further
enhances the figure of merit.Comment: 20 pages, 5 figure
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