We present a new class of long-period fiber gratings that can be used as in-fiber, low-loss, band-rejection filters. Photoinduced periodic structures written in the core standard communication-grade fibers couple light from fundamental guided mode to forward propagating cladding modes and act spectrally selective loss elements with insertion losses backreflections <-80 dB, polarization-mode-dispersions <0.01 ps polarization-dependent-losses <0.02 dB.

We develop a theory for laser-induced periodic surface structure by associating each Fourier component of induced with the corresponding inhomogeneous energy deposition just beneath surface. assume that roughness, confined to region height much less than wavelength light, is responsible symmetry breaking leading this deposition; we find strong peaks in space, which leads predictions fringe patterns spacing and orientation dependent on angle incidence polarization damaging beam. The nature...

We present a simple prescription for the derivation of electronic contributions to nonlinear optical response crystals in independent particle approximation. Semiconductor Bloch equations are found that include previously neglected effects intraband motion. Applying perturbation theory clean, cold semiconductors we find expressions susceptibilities lacking unphysical divergences at zero frequency have plagued other calculations. For these materials well-behaved, general...

We present a new general formalism for investigating the second-order optical response of solids, and illustrate it by deriving expressions susceptibility tensor ${\ensuremath{\chi}}_{2}(\ensuremath{-}{\ensuremath{\omega}}_{\ensuremath{\Sigma}};{\ensuremath{\omega}}_{\ensuremath{\beta}},{\ensuremath{\omega}}_{\ensuremath{\gamma}}),$ where ${\ensuremath{\omega}}_{\ensuremath{\Sigma}}={\ensuremath{\omega}}_{\ensuremath{\beta}}+{\ensuremath{\omega}}_{\ensuremath{\gamma}},$ clean, cold...

We report the results of a detailed investigation into properties periodic damage structure that can be produced on nominally smooth surfaces solids when they are irradiated with single beam intense laser radiation. The study is primarily concerned extracting information from Fourier transform as observed via Fraunhofer diffraction pattern by reflecting cw surface. In particular, patterns in Ge, Si, Al, and brass pulsed 1.06- 0.53-\ensuremath{\mu}m radiation compared function angle incidence...

We present a macroscopic theory for anisotropic second- and third-harmonic generation obtained in reflection from the surface bulk of cubic centrosymmetric single crystals. The is based on possible electric dipole, quadrupole, magnetic dipole sources. Completely general expressions harmonic fields are (100), (111), (110) faces independent details response but consistent with crystal symmetry. results agree all existing experimental data by various groups during past few years. possibility...

A quantum-mechanical linear-response formalism is used to calculate the frequency shift and lifetime of an excited atom near arbitrary flat interface. The results depend on frequency-dependent field susceptibilities, in vicinity interface can be expressed terms appropriate Fresnel reflection coefficients; contributions from surface excitations are easily identified. As examples, we consider above a metal dielectric waveguide.

Formulas are presented that provide clear physical insight into the phenomenon of extrinsic optical scattering loss in photonic crystal waveguides due to random fabrication imperfections such as surface roughness and disorder. Using a photon Green-function-tensor formalism, we derive explicit expressions for backscattered total transmission losses. Detailed calculations planar crystals yield values overall agreement with experimental measurements, including full dispersion characteristics....

A detailed theoretical treatment is presented of bound-mode to Bragg reflection and radiation-mode coupling loss in a tilted optical-fiber phase grating. Numerical predictions the effects grating tilt on spectral characteristics such are calculated. These compared with experimentally measured spectra strong gratings written by ultraviolet irradiation deuterium-sensitized fiber angles ranging from 0° 15°. Good agreement obtained between experimental results.

We demonstrate room temperature coherent generation and control of a directional photocurrent in bulk GaAs via simultaneous one- two-photon interband absorption processes using phase-related 1 ps or 175 fs pulses at 0.775 $1.55\ensuremath{\mu}\mathrm{m}$. Electrical currents generated low-temperature-grown (LT) normal are collected gold electrodes. Current densities as high $3\mathrm{nA}/\ensuremath{\mu}{\mathrm{m}}^{2}$ LT-GaAs measured for injected carrier low...

Laser-induced periodic structure on solid surfaces can be understood as a universal phenomenon which occurs for broad range of wavelengths and different laser polarization states in both polariton-active -inactive media. Circularly polarized light has been used, the first time, to generate structures; these show an interesting dependence sense rotation.

We discuss the second-harmonic generation of light at metal surfaces within hydrodynamic theory electron gas; expressions for phenomenological parameters $a$ and $b$ Rudnick Stern are presented, possibility a resonance in optical or near-uv frequencies is discussed. A recent plasmon-enhanced experiment Simon et al. analyzed, use such experiments to determine considered; new proposed aid determination.

We perform a perturbative calculation of the third order optical conductivities doped graphene, using approximations valid around Dirac points and neglecting effects due to scattering electron–electron interactions. In this limit analytic formulas can be constructed for conductivities. discuss in detail results harmonic generation, Kerr effect two-photon carrier injection, parametric frequency conversion, two-color coherent current injection. find complicated dependence on chemical potential...

We express the optical properties of multilayered hyperbolic metamaterials (HMMs) in terms Fresnel reflection coefficients at boundary between metamaterial and ambient medium. Formation a band bulk propagating modes HMMs located far outside lightcone homogeneous isotropic media is demonstrated. Exotic behavior HMMs, such as broadband Purcell effect suppressed outward scattering, reproduced. Conditions under which metal-dielectric multilayer can be approximated by effective medium with...

Entanglement is a fundamental resource in quantum information processing.Several studies have explored the integration of sources entangled states on silicon chip, but devices demonstrated so far require millimeter lengths and pump powers order hundreds milliwatts to produce an appreciable photon flux, hindering their scalability dense integration.Microring resonators been shown be efficient pairs, state emission has never proven these devices.Here we report first demonstration, best our...

We show theoretically that interband transitions in a bulk semiconductor via coherent one- and two-photon absorption leads to the formation of an electrical current whose direction is controlled by relative phase beams. The phenomenon can occur centrosymmetric noncentrosymmetric materials; easily measurable currents are predicted for GaAs under realistic experimental conditions.

Within the context of Maxwell Garnett model, we calculate nonlinear susceptibility a composite optical material comprised spherical inclusion particles contained within host material. We allow both constituents to respond nonlinearly and exhibit linear absorption. Our treatment takes complete account tensor nature interaction, under assumption that each constituent is isotropic macroscopically isotropic. The theory predicts there are circumstances which can possess larger than either its...

The mechanisms responsible for the growth of periodic surface structure on Ge irradiated by 1.06-\ensuremath{\mu}m laser pulses from a single beam are investigated. Time-resolved diffraction weak cw probe developing structures, coupled with electron-microscope pictures resulting morphology, is used to identify four distinct regimes ripple formation at different incident fluences. At low fluences, develops when thin (1 \ensuremath{\mu}M wide) isolated, molten strips resolidify solid...

A phenomenological treatment of surface second-harmonic generation that can be applied to a host geometries interest is presented. We consider four standard experimental and show the expressions for generated power all written in one compact form, from which dependence signal on polarization, angle incidence, other parameters extracted. The bulk also included with this formalism, as we explicity geometry.

We use two-beam second-harmonic generation to separate the surface (electric dipole origin) and bulk (magnetic electric quadrupole contributions second-order nonlinear optical response of an isotropic gold film. The is unambiguously observed explained by momentum damping electrons in a free-electron model. Although effects could be enhanced inhomogeneous local fields metal nanostructures have been used model from metamaterials [Y. Zeng et al., Phys. Rev. B 79, 235109 (2009)], we find that...

We argue that a photon wave function can be introduced if one is willing to redefine, in what we feel physically meaningful way, wishes mean by such function. The generation of spontaneously emitting atom discussed.

A quantum-mechanical linear-response formalism is further developed to deal with the energy-level shifts of excited states atoms near an arbitrary flat interface. We establish physical interpretations for different components these shifts, and as examples treat in free space, a perfect conductor, metal, dielectric waveguide. The effects surface excitations such plasmons waveguide modes are considered detail; we point out certain striking differences particular excitations.

Quantum interference of one- and two-photon excitation unbiased semiconductors yields ballistic currents carriers. The magnitudes directions the spin orientations carriers are controlled by polarization relative phase exciting femtosecond laser fields. We provide direct experimental evidence for optically injected detecting a phase-dependent spatial shift circularly polarized photoluminescence in cubic ZnSe.