Using near-field optical microscopy, we investigate propagation and scattering of surface plasmon polaritons (SPP's) excited in the wavelength range 780-820 nm at nanostructured gold-film surfaces with areas 200-nm-wide scatterers arranged a 400-nm-period triangular lattice containing line defects. We observe SPP reflection by such an area guiding along defects 782 nm, as well significant deterioration these effects is 815 thereby directly demonstrating band gap effect showing first examples...

Time-dependent spontaneous Raman spectra of optically pumped GaAs have been measured with subpicosecond time resolution. When the injected carrier density is less than ${10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, we temporally resolve growth induced nonequilibrium LO-phonon population and deduce an average electron-phonon scattering about 165 fs. For higher densities, substantial time-dependent changes are observed in which result from screening LO phonons by free carriers relaxation to band edges.

We report measurements of ultralong coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time 372 ps, corresponding to a homogeneous linewidth 3.5 microeV, which is significantly smaller than the observed single-dot luminescence. Time-resolved luminescence lifetime dot ground state 800 demonstrating presence pure finite temperature. The width limited only temperatures approaching 0 K.

Biexciton binding in GaAs quantum wells has been investigated for a range of well thicknesses (80--160 \AA{}) with spectrally resolved photoluminescence and transient degenerate four-wave mixing. Both light heavy hole biexcitons are observed. The ratio the energy biexciton to that exciton is found be $\ensuremath{\approx}0.2$, nearly independent width over range. A new theoretical calculation agrees very experimental ratio. This larger than predicted by Hayne's rule three-dimensional biexcitons.

A compact and efficient polarization splitting rotating device built on the silicon-on-insulator platform is introduced, which can be readily used for interface section of a diversity circuit.The compact, with total length few tens microns.It also simple, consisting only two parallel wire waveguides different widths, thus requiring no additional nonstandard fabrication steps.A insertion loss 0.6dB an extinction ratio 12dB have been obtained experimentally in whole C-band. ©2011 Optical...

The recombination lifetime in phosphorus-doped hydrogenated amorphous silicon is determined from the dispersive photocurrent decay following a short-pulse excitation. electron drift mobility and dispersion parameter $\ensuremath{\alpha}$ are obtained as well. It found that temperature dependent expected for extended-state transport controlled by multiple trapping. A lower limit to determined: ${\ensuremath{\mu}}_{c}>~1$ ${\mathrm{cm}}^{2}$/V.s.

The ultrafast gain and index dynamics in a set of InAs-InGaAs-GaAs quantum-dot (QD) amplifiers are measured at room temperature with femtosecond resolution. role spectral hole-burning (SHB) carrier heating (CH) the recovery compression is investigated detail. An hole within /spl sim/100 fs measured, comparable to bulk quantum-well amplifiers, which contradicting relaxation bottleneck electrically pumped QD devices. CH quantitatively compared results on an InGaAsP amplifier. Reduced for both...

The ultrafast dynamics of gain and refractive index in an electrically pumped InAs-InGaAs quantum-dot (QD) optical amplifier are measured at room temperature using differential transmission with femtosecond time resolution. Both absorption regions investigated. While the bleaching recovery occurs on a picosecond scale, compression recovers /spl sim/100-fs constant, making devices based such dots promising for high-speed communications.

The radiative and nonradiative decay rates of InAs quantum dots are measured by controlling the local density optical states near an interface. From time-resolved measurements, we extract oscillator strength efficiency their dependence on emission energy. our results a theoretical model, determine striking overlap electron hole wavefunctions dot size. We conclude that quality is best for large dots, which important in order to optimally tailor emitters for, e.g., electrodynamics experiments.

We report measurements of two-photon transitions to the biexciton state and exciton-biexciton (M band) in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As multiple quantum wells by spectrally resolving self-diffraction a four-wave-mixing experiment. Furthermore, nonlinear beats between coherently prepared population excitons biexcitons are observed. The analysis yields binding energy 1.8 meV for 116-A\r{} wells.

We have measured the absolute values of second-harmonic generation (SHG) coefficient |d| for zinc-blende II-VI semiconductors ZnTe, ZnSe, and ZnS at room temperature. The investigated spectral region fundamental radiation ${\ensuremath{\lambda}}_{F}$ ranges from 520 to 1321 nm using various pulsed laser sources. In transparent semiconductors, SHG exceeds birefringent materials as ammonium dihydrogen phosphate (ADP) potassium (KDP) by one or two orders magnitudes. Above ${E}_{0}$ band gap a...

Quantum mechanically indistinguishable particles such as photons may show collective behavior. Therefore, an appropriate description of a light field must consider the properties assembly instead independent particles. We have studied multiphoton correlations up to fourth order in single-mode emission semiconductor microcavity weak and strong coupling regimes. The counting statistics single were recorded with picosecond time resolution, allowing quantitative measurement few-photon bunching...

An efficient TE–TM polarization converter built on a silicon-on-insulator nanophotonic platform is demonstrated. The strong cross-polarization coupling effect in air-cladded photonic-wire waveguides employed to realize the conversion. A peak efficiency of 87% (−0.6 dB insertion loss) measured experimentally. conversion >92% with an overall loss <−1.6 obtained wavelength range 40 nm. proposed device compact, total length 44 μm and can be fabricated one lithography etching step.

A grating coupler for interfacing between single-mode fibers and photonic circuits on silicon-on-insulator is demonstrated. It consists of columns fully etched crystal holes, which are made in the same lithography etching processes used making wire waveguide. The holes have a diameter around 143 nm, defined with electron-beam lithography. peak coupling efficiency 42% at 1550 nm 1 dB bandwidth 37 as well low back reflection, achieved. performance proposed comparable to that based conventional...

This letter demonstrates optical demultiplexing of a 1.28-Tb/s serial differential phase-shift-keying data signal using nano-engineered silicon waveguide. We first present error-free performance at 640 Gb/s and then 1.28 Tb/s with characterization all 128 channels. Bit-error rates below 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> are achieved for some channels forward-error-correction limit channels, corresponding to 1.19-Tb/s signal.

This paper presents the experimental demonstrations of using a pure nanoengineered silicon waveguide for 1.28 Tb/s serial data optical waveform sampling and Tb/s-10 Gb/s error-free demultiplexing. The 330-fs pulses are resolved in each 780-fs time slot sampling. Error-free operation is achieved

We demonstrate the self-phase modulation (SPM) of a single-cycle THz pulse in semiconductor, using bulk n-GaAs as model system. The SPM arises from heating free electrons electric field pulse, leading to an ultrafast reduction plasma frequency, and hence strong modification THz-range dielectric function material. is observed directly time domain. In frequency domain it corresponds frequency-dependent refractive index nonlinearity n-GaAs, found be both positive negative within broad spectrum,...

We have successfully demonstrated all-optical wavelength conversion of a 640-Gbit/s line-rate return-to-zero differential phase-shift keying (RZ-DPSK) signal based on low-power four wave mixing (FWM) in silicon photonic chip with switching energy only ~110 fJ/bit. The waveguide dispersion the nanowire is nano-engineered to optimize phase matching for FWM and power used processing low enough reduce nonlinear absorption from two-photon-absorption (TPA). These results demonstrate that...

We report on a direct observation of free-exciton thermalization in quantum-well structures. A narrow energy distribution free $1s$ excitons is created ZnSe-based quantum wells by emission one LO phonon after optical excitation the continuum states with picosecond laser pulses. The subsequent relaxation dynamics within $1s$-exciton dispersion directly monitored time-resolved studies phonon-assisted photoluminescence. It demonstrated that remains nonthermal for some 100 ps. observed...

The room-temperature dephasing in InAs/GaAs self-assembled quantum dots is measured using two independent methods: spectal-hole burning and four-wave mixing. Dephasing times weakly dependent on the excitation density are found, with a low value of $290\ifmmode\pm\else\textpm\fi{}80 \mathrm{fs}$ from $260\ifmmode\pm\else\textpm\fi{}20

A new method to measure the time-dependent coherence of both homogeneously and inhomogeneously broadened optical excitations in solids is presented. The degree resonantly excited light emission deduced from intensity fluctuations over directions (speckles). This determines decays separately, thus distinguishing lifetime pure dephasing. secondary excitons semiconductor quantum wells investigated. Here combination static disorder inelastic scattering leads a partially coherent emission....

The optical properties of CdSe nanostructures grown by migration-enhanced epitaxy on ZnSe are studied time-, energy-, and temperature-dependent photoluminescence excitation spectroscopy, as well polarization-dependent four-wave mixing two-photon absorption experiments. consist a coherently strained ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{S}\mathrm{e}/\mathrm{Z}\mathrm{n}\mathrm{S}\mathrm{e}$ quantum with embedded islands higher Cd content sizes few nanometer due to...