Search

The goal of the paper is to present the material jurisdiction of the Court of Competition and Consumer Protection in light of the constitutional principle of entity equality. The regulations of Art. 32 of the Constitution of the Republic of Poland include the principle of equality, which also covers entrepreneurs. In Poland, in addition to administrative courts that control the legality of administrative decisions, there is also the Court of Competition and Consumer Protection, which hears cases concerning administrative decisions from a material perspective. The analysis of the regulations indicates that the jurisdiction of this court has been determined without justification. The paper proves the thesis that the material jurisdiction of the Court of Competition and Consumer Protection has been determined arbitrarily by the legislator violating the constitutional principle of equality. The following methods were applied: dogmatic-legal and analytic-synthetic.

Ustawodawca z różnych przyczyn przekazuje do rozpoznania przez sądy powszechne sprawy administracyjne. Sprawy te załatwiane są przez organ administracyjny decyzją, a odwołanie kierowane jest do sądu powszechnego. Przykładem takiej procedury, zwanej hybrydową, jest postępowanie w sprawach z zakresu ubezpieczeń społecznych.

Background The aim of this study was to determine whether spinal cord stimulation (SCS) using 3D neural targeting provided sustained overall and low back pain relief in a broad routine clinical practice population. Study Design and Methods This was a multicenter, open-label observational study with an observational arm and retrospective analysis of a matched cohort. After IPG implantation, programming was done using a patient-specific, model-based algorithm to adjust for lead position (3D neural targeting) or previous generation software (traditional). Demographics, medical histories, SCS parameters, pain locations, pain intensities, disabilities, and safety data were collected for all patients. Results A total of 213 patients using 3D neural targeting were included, with a trial-to-implant ratio of 86%. Patients used seven different lead configurations, with 62% receiving 24 to 32 contacts, and a broad range of stimulation parameters utilizing a mean of 14.3 (±6.1) contacts. At 24 months postimplant, pain intensity decreased significantly from baseline (ΔNRS = 4.2, N = 169, P

The discussion progressed in this chapter is about the protection of organizational knowledge in competitive environments. Knowledge can leak in the value creation networks embedded in knowledge-intensive firms, and a collaborative approach can be utilized to minimize risk and increase sustainability. For knowledge to be preserved from unintentional outflow, its confidential nature and description must be understood at all levels. Loss of knowledge can occur at any point; whether it is through the process of consultation or when employees do their work. Forfeiture of information can be unintended or a planned effort. To prevent such unintended leakage, it is important to develop a shared mindset among employees to minimize the risk. The socio-technical system is a philosophical framework that enables companies to simultaneously consider both ethical and technical systems in order to best match the technology and the people involved. In this paper we show how the socio-technical system can be applied to prevent knowledge leakage.

When elliptically polarized maximally entangled states are considered, i.e., states having a non random phase factor between the two bipartite polarization components, the standard settings used for optimal violation of Bell inequalities are no longer adapted. One way to retrieve the maximal amount of violation is to compensate for this phase while keeping the standard Bell inequality analysis settings. We propose in this paper a general theoretical approach that allows determining and adjusting the phase of elliptically polarized maximally entangled states in order to optimize the violation of Bell inequalities. The formalism is also applied to several suggested experimental phase compensation schemes. In order to emphasize the simplicity and relevance of our approach, we also describe an experimental implementation using a standard Soleil-Babinet phase compensator. This device is employed to correct the phase that appears in the maximally entangled state generated from a type-II nonlinear photon-pair source after the photons are created and distributed over fiber channels., 8 pages

Reporting delay occurs frequently in the case surveillance of a disease such as HIV/AIDS. To evaluate the current trend of incidence, it is important to consider incidence estimates adjusted for reporting delays and the uncertainty associated with this adjustment. For a surveillance system in which cases are reported monthly, there is no straightforward method for constructing the confidence interval estimators for annual incidence or incidence for a period longer than a month. This is because the monthly incidence estimators are not independent and the correlations among them are not available. Furthermore, to estimate the incidence for a specific risk, or exposure, group (e.g. men who have sex with men), we also have to consider the uncertainty associated with the counts from cases reported without an identified risk. Cases with no reported risk are assigned proportionally to each risk group on the basis of experience with cases reported initially with no reported risk but reported later with an identified risk. In this article, we introduce a method for combining the uncertainties associated with both reporting delay and risk redistribution. An estimator for the covariance between two incidence estimators is also provided so that we can make pairwise comparisons and discover any significant changes in incidence over time. Results are applied to evaluating the current trends in AIDS incidence among men who have sex with men in the United States.

Corridor preservation is an issue of growing concern. The costs of providing transportation infrastructure are escalating, particularly in growing urbanized areas. Right-of-way (ROW) costs often represent the single largest expenditure for a transportation improvement. ROW becomes so costly that jurisdictions are unable to provide needed transportation infrastructure, the existing system will fail to function as planned, and quality of life will suffer. It is critical for local governments to work within their authority to ensure that land for future transportation facilities is preserved as development occurs. Better coordination of land use and transportation decisions will result in a variety of benefits, including earlier public notification of the ROW needs for planned road improvements, less need to relocate homes or businesses when improvements are made, and less damage to existing sites when the land is acquired. Many jurisdictions have some method of ROW preservation, but most lack a systematic program for preserving ROW and managing access. Those that have succeeded have assembled a variety of tools they can mix and match to the circumstances at hand. No single method works for all situations or is legally available in every state. The following measures can help ensure a more successful program: develop a long-range transportation plan with broad community support, set clear priorities and complete projects on time, establish an advance acquisition funding source, establish a systematic program of policies and regulations, and provide a range of mitigation measures to address potential hardships and preserve property rights.

The influence of absorption or gain on the Bragg diffraction efficiency of intracavity refractive index gratings is analyzed. Losses drastically reduce the diffraction efficiency of the device which can nevertheless be optimized in order to limit their inauspicious influence. On the contrary, in amplifying intracavity media very large diffraction efficiencies are obtained even with small integrated refractive index modulations. The optimization of the device for maximum diffraction efficiency or vanishing reflectivity could find applications in tunable lasers and in high contrast amplifying optical signal processing.

We investigate the influence of thermally induced higher order aberrations on the fundamental mode of a rod solid-state laser. The perturbations of the laser due to the most common aberrations (spherical aberration and astigmatism) are studied for several sizes of the fundamental mode. Results concerning the additional losses and beam quality degradation induced by these aberrations are also presented and demonstrate that for a large overlapping of the beam size and the laser rod, the spherical aberration amplitude must not exceed 0.5λ for the cavity to oscillate. The influence of gain saturation also analyzed in the model is shown to be of less importance.

Nous reportons l'observation d'une rotation de polarisation geante de plus de 120° dans une microcavite semi-conductrice asymetrique contenant un puits quantique de (Cd,Mn)Te/(Cd,Mg)Te. Ce resultat obtenu pour un champ modeste (0,6 tesla) et a basse temperature (5 kelvins) est due a la forte diminution du couplage exciton-cavite produite par interaction d'echange dans le puits de semiconducteur semi-magnetique.

Nous presentons une etude analytique approfondie de la diffraction de Bragg par un reseau d'indice place dans une cavite Fabry-Perot. Les proprietes diffractives d'un reseau donne se trouvent largement exaltees par son insertion dans un resonateur de Fabry-Perot. Ceci permet d'envisager l'utilisation de materiaux aux proprietes diffractives naturellement mediocres, ou des reseaux de faible epaisseur.

We investigate the influence of nonlinear optical Faraday rotation on polarization multistability and modulational instabilities in nonlinear resonators. The potential use of gyrotropic cavities for implementing a light polarization-controlled set–reset flip–flop element and a high-repetition-rate pulse train generator is analysed.

Carrier diffusion and electron-hole recombination are shown to be considerably slowed down in ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$ semimagnetic semiconductors due to the efficient trapping of electrons on manganese sites. The theoretical interpretation is based on population dynamics, charge continuity equations, and Poisson's law. A simple analytical solution of this complicated system of equations is in very good agreement with the numerical one for a large range of durations of the write pulses (from 100 ps to 1 \ensuremath{\mu}s). Both calculations predict a reduction of electron mobility by a factor of 6000. These theoretical predictions are confirmed by the results of an experimental study performed by using the simple grating technique: We observe the temporal evolution of the diffracted signal when a continuous read beam is used to read gratings of different wavelengths encoded in the material by interfering write laser pulses. An effective ambipolar mobility of $0.54{\mathrm{cm}}^{2}/\mathrm{V}\mathrm{}\mathrm{s}$ is measured, which provides a value of $3400{\mathrm{cm}}^{2}/\mathrm{V}\mathrm{}\mathrm{s}$ for the intrinsic mobility in ${\mathrm{Cd}}_{0.7}{\mathrm{Mn}}_{0.3}\mathrm{Te}.$ This low ambipolar mobility could make this efficient material potentially interesting for parallel optical processing in the microsecond range.

Efficient free-carrier-induced refractive-index gratings are recorded in Cd 0.7 Mn 0.3 Te semimagnetic semiconductors owing to the trapping of electrons. Such a process also generates a space-charge field and a subsequent photorefractive grating with a smaller efficiency. These gratings are studied both experimentally and theoretically as well as the polarization modulation of diffraction efficiency due to residual birefringence.

Introduction: We describe trends in seropositivity among clients attending publicly funded HIV counseling and testing sites across the United States and discuss implications for prevention policy. Methods: The present analysis used client-level data from 1990 through 1994 for 26 of 65 state, territorial, and local health departments receiving Centers for Disease Control and Prevention funds. Logistic regression was used to predict the proportion of HIV tests that were positive. Curves were created representing adjusted HIV seropositivity trends for 1990 through 1994. Results: HIV seropositivity rates were higher before 1992. Throughout, rates were higher among men, most racial/ethnic minorities tested, and persons 30 years or older. Although rates for men remained higher than those for women, the gap has narrowed in recent years. For both men and women, rates remained low for those reporting heterosexual activity as their only potential risk for HIV. Over time, more high-risk seronegatives are being repeatedly tested. Conclusions: Lower, stabilized seropositivity rates after 1992 reflect large increases in testing volume, increasing frequency of repeat testing, and fewer asymptomatic-infected persons entering this public system. Various program innovations including enhanced outreach, improved access, rapid testing, and client-centered counseling should be considered as strategies to increase the number of infected persons who learn their serostatus early and enter into medical care.

Ce travail vise a l'elaboration d'un systeme d'amplification faible bruit de signaux hyperfrequences sur porteuse optique. Nous avons mene une etude experimentale de l'amplification Raman dans des fibres optiques monomodes a 1550nm. La configuration contra-propageante –la moins bruitee– permet d'atteindre des gains nets de plus de 25dB, elle s'est aussi montree plus performante en termes de RIN (relative intensity noise) qu'un EDFA commercial. Une analyse theorique de l'amplification Raman a ete conduite dans le domaine spectral afin de quantifier le transfert de RIN de la pompe vers le signal. L'analyse a montre une decroissance de ce transfert a hautes frequences que l'on considere un laser de pompe monochromatique faiblement module ou, a l'oppose, pseudo-incoherent. Par contre, a basses frequences, le laser de pompe monochromatique faiblement module apporte un exces de bruit qui n'est pas present avec la pompe pseudo-incoherente. Ce type de source de pompe peut donc presenter un interet tout particulier pour le developpement d'amplificateurs Raman faible bruit pour les liaisons opto-hyperfrequences. Une autre piste envisagee est la reduction du bruit d'emission spontanee amplifiee. Nous avons etudie les moyens a mettre en œuvre pour parvenir a diminuer ce bruit. L'utilisation de deux lasers de pompe de meme puissance presentant un faible decalage spectral (devant la largeur de la transition Raman) doit permettre d'atteindre ce resultat. Les descriptions holographique, "optique non lineaire" ou quantique de la diffusion Raman bifrequence indiquent que pour une reduction effective du bruit d'emission spontanee, il faut que les deux pompes soient opposees en amplitude.

Nous presentons les premiers resultats experimentaux de diffusion Raman stimulee dans une fibre a cristal photonique a coeur creux rempli d'un liquide a fort gain Raman d'indice inferieur a celui de la silice. Cette etude preliminaire ouvre la voie vers de nombreuses perspectives pour des applications en traitement du signal optique.

We report a giant photoinduced Faraday rotation in a $\mathrm{CdTe}/{\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{Te}$ multiple quantum well structure when the laser frequency is tuned close to the fundamental excitonic transition of the quantum well and saturation sets in. At the same time we observe stimulated emission and buildup of magnetization through photon spin recycling in the presence of a magnetic field which was analyzed by a time-resolved linearly polarized pump and probe technique. The magnetization buildup is also seen in the absence of the seeding magnetic field and by using a circularly polarized pump beam.

Abrege: Nous etudions les nonlinearites de rotation de polarisation et d'ellipticite d'une microcavite de semiconducteur, contenant 18 puits quantiques, en regime de couplage fort ou la resonance excitonique du materiau intracavite et celle de la cavite sont en forte interaction. Les experiences sont realisees grâce a un generateur-amplificateur parametrique optique pompe par un laser Nd:YAG « Picoseconde », et les mesures effectuees par un systeme de detection compose de deux balances optiques. Le resultat des mesures montrent qu'une rotation Kerr de l'ordre de 1,4 ° a lieu a temperature ambiante sous un champ magnetique de 1,4 kG.

A theoretical investigation of the performance of single-mode coupled spontaneous parametric downconversion sources is proposed, which only requires very few assumptions of practical interest: quasi-degenerate collinear generation and narrow bandwidth obtained through spectral filtering. Other assumptions, such as pump-beam spatial and temporal envelopes, target single-mode profile and size, and nonlinear susceptibility distribution, are only taken into account in the final step of the computation, thus making the theory general and flexible. Figures of merit for performance include absolute coupled brightness and conditional coupling efficiency. Their optimization is investigated using functions that only depend on dimensionless parameters, so that the results provide the best experimental configuration for a whole range of design choices (e.g., crystal length, pump power, etc.). A particular application of the theory is validated by an experimental optimization obtained under compatible assumptions. A comparison with other works and proposals for numerically implementing the theory under less stringent assumptions is also provided.

We present a detailed analysis of the giant excitonic Faraday rotation in CdTe CdMnTe quantum wells when the laser frequency is tuned across the excitonic resonance. This excitonic Faraday rotation effect is very well accounted for by modeling the excitonic transition with a two-level system. The value found for the excitonic Verdet constant, 7 × 106 degrees/T/cm, is about two orders of magnitude larger than that measured for interband transitions in the bulk or superlattices of semimagnetic semiconductors, making this effect attractive to study magneto-optical properties of single quantum wells.

Fast and complete characterization of pulsed spontaneous parametric down conversion (SPDC) sources is important for applications in quantum information processing and communications. We propose a simple method to perform this task, which only requires measuring the counts on the two output channels and the coincidences between them, as well as modeling the filter used to reduce the source bandwidth. The proposed method is experimentally tested and used for a complete evaluation of SPDC sources (pair emission probability, total losses, and fidelity) of different bandwidths. This method can find applications in the setting up of SPDC sources and in the continuous verification of the quality of quantum communication links.

We have experimentally implemented the distribution of photon pairs produced by spontaneous parametric down conversion through telecom dense wavelength division multiplexing filters. Using the measured counts and coincidences between symmetric channels, we evaluate the maximum fringe visibility that can be obtained with polarization entangled photons and compare different filter technologies., Comment: 3 pages, 4 figures, submitted to Optics Letters

A microscopic theory of interband Faraday rotation in semimagnetic semiconductors is presented, which takes into account both the wavevector dependence of the exchange interaction and the anisotropy of the mixing of valence band electron wavefunctions when a magnetic field is applied. Comparison of its conclusion and the experimental spectra confirms that the decrease in wavevector of the exchange interaction depends neither on the manganese concentration nor on the sample temperature as already observed for Γ and L exciton shifts The small value of the exchange half-width (k0 = 2.6 × 106 cm-1 for a Lorentzian shaped exchange interaction in CdMnTe) also indicates that the values of the exchange integrals at k = 0 could be somewhat larger than those derived from the magnetic field dependence of excitonic transition frequencies.

Slow-mode micro-structured waveguides enable a large enhancement of optical nonlinearities. Using a generalization of the local field factor theory of nonlinear homogeneous media, we review the impact of the group velocity reduction on the hierarchy of the semi-conductor nonlinearities. As an illustration, we experimentally and theoretically reported an intrinsic limitation concerning the Raman amplification of short pulses in silicon nanowires through the self-phase modulation induced by both the optical Kerr effect and free-carrier refraction. Hence, we provide a fundamental insight on the nonlinear interaction of short pulses for the design of future slow-mode devices.

We consider the Raman amplification problem for silicon waveguides in the regime in which both the pump and signal pulses are relatively short but wide enough that their duration exceeds the phonon lifetime (about 3 ps in silicon). We use the coupled pump-signal equations for numerical simulations that include all competing nonlinear effects such as self- and cross-phase modulations, two-photon and free-carrier absorptions, and changes in the refractive index induced by the free carriers. However, numerical simulations do not provide much physical insight. For this reason, we also develop an approximate analytic approach for solving the Raman amplification problem. We introduce the concept of an effective Raman gain and show analytically how it depends on the pump bandwidth. As the pump spectrum broadens inside the silicon waveguide, the effective Raman gain is reduced considerably. We obtain an analytical form of the nonlinear phase accumulated during propagation inside a silicon waveguide and use it to calculate the total spectral broadening experienced by a pump pulse. Using this result, we can predict changes in the effective Raman gain as a function of pump pulse energy. A comparison of our predictions with the recent experimental data shows that our model is reasonable and captures the essential physics.

Spontaneous parametric downconversion (SPDC) sources are an essential element of quantum communication and quantum information processing systems. Their quality can be hampered by spectral, temporal, or spatial distinguishability of the two photons of a generated pair. Even when such defects have been corrected, the ultimate quality of the SPDC source is limited by the intrinsic multiple pair generation. In this paper, the effect of transmission, filtering and detection losses and asymmetrical spectral bandwidths in the photon pair paths on the visibility of the two-photon interference delivered by the SPDC source and its useful pair rate are investigated. In this investigation, two subcases are distinguished: deterministic and statistical splittings of the generated pairs, whatever the coherence of the multiple pairs. We show that the visibility is strongly degraded by a spectral bandwidth asymmetry, while the losses mainly affect the measured coincidence probability. The deterministic splitting configuration is shown to be generally more advantageous, although statistical splitting may present some advantages in applications with a narrow bandwidth requirement, such as those involving quantum memories. Moreover, while pump-induced optical noise only produces small visibility reductions, dark counts of the single-photon detectors are shown to limit the maximum possible visibility, particularly in the case of high-loss photon pair sources. Because our model quantifies the intrinsic limitations due to double pair emission in a simple way, the results presented can be used to optimize the design of SPDC sources and choose the optimum trade-offs between several key parameters such as visibility, generation probabilities, and spectral bandwidth, in particular for small bandwidth SPDC sources in the perspective of quantum networking and computing applications.

The giant Faraday rotation (larger than 90°) photoinduced in ZnMnTe or CdMnTe by picosecond duration pump pulses is analysed by the time-resolved pump and probe technique. Slow thermal and fast photocarrier-induced processes are found to occur depending on the choice of the semimagnetic semiconductor sample.

We experimentally and theoretically study self-phase modulation by Kerr effect in a liquid filled hollow core photonic crystal fiber. We perform a complete characterization of the linear optical properties of the hollow core photonic band gap fiber filled with deuterated acetone to determine all the characteristics of the propagation mode. The nonlinear coefficient of the fiber is determined by fitting the output spectra broadened by self-phase modulation with a new analytical expression giving the spectra of a secant hyperbolic pulse transmitted through a Kerr media. The experiment allows a precise determination of the nonlinear index change of acetone-d6 equal to (1.15$\pm$0.17)x10-19 m2W-1., to be published in JOSAB

We experimentally show that the self-phase modulation of picosecond pump pulses, induced by both the optical Kerr effect and free-carrier refraction, has a detrimental effect on the maximum on-off Raman gain achievable in silicon on insulator nanowaveguides, causing it to saturate. A simple calculation of the Raman gain coefficient from the measured broadened output pump spectra perfectly matches the saturated behavior of the amplified Raman signal observed experimentally at different input pump powers., Accepted for publications in Applied Physics Letters

We present a Raman generator based on a 35 cm long hollow core photonic crystal fiber entirely filled with ethanol emitting on a nearly-Gaussian beam. The power conversion efficiency from the pump at 532 nm to the first Stokes order of ethanol at 630 nm is 67%. Temporal profiles, mode patterns and power stability are also analyzed.

Starting from the expression of the power dissipation in a material, we analyze the competition between parametric and resonant processes in nonlinear optics. It is shown that this leads to the suppression of the medium excitation when the phase mismatch existing in the parametric process is small. This results from destructive interference of two different medium excitation pathways which minimizes energy dissipation. This analysis is applied to three examples: three-photon resonantly enhanced third harmonic generation and Stokes-anti-Stokes coupling in stimulated Raman and Brillouin scattering.

The nearly degenerate four-wave mixing technique is used to investigate the physical origin of period doubling in the route toward chaos. This spectroscopic approach identifies resonantly enhanced nearly degenerate four-wave mixing processes as being responsible for the generation of subharmonic frequencies. The technique presented in the case of GaAlAs semiconductor lasers could be applied to the study of monomode instabilities occurring in any laser or bistable devices.

High-efficiency pulse compression has been obtained by using an externally pumped intracavity Raman oscillator. Through stimulated Raman scattering, the energy of a primary, long-pulse-duration omega(L) laser is downconverted and stored at the first Stokes frequency omega(1s) in a high-Q cavity containing the Raman medium. Then this electromagnetic energy is quickly extracted at the second Stokes frequency. This technique, which uses hydrogen gas as the Raman medium, permits a 25-nsec-duration ruby-laser pulse shortening by a factor of 12.5 with a near 50% quantum efficiency. Contrary to the case of intracavity Raman oscillators or amplifiers, this method can also be used with absorbing laser media.

Very-high-efficiency (80%) Raman amplification of a narrow-band injected Stokes signal has been achieved in the case in which pump and Stokes linewidths are both narrower than Raman transition width. Under such conditions, the Stokes-beam amplification is obtained without line broadening, permitting the creation of widely tunable powerful monochromatic sources when tunable lasers are used. With fixed-frequency pump lasers, tunability within the Raman linewidth has also been demonstrated. With a pump linewidth much broader than that of the injected Stokes signal, a spectral compression rate up to 16 has been achieved by using this Raman amplification technique.

A new filtering technique is proposed that associates the high dispersion of standard reflection gratings with the tuning speed of acousto-optic cells. Tuning is performed by adjusting the grating period so that the chosen wavelength is at Bragg resonance. In this way, the selected wavelength always experiences a maximum diffraction efficiency, ensuring good uniformity. Using a commercial acousto-optic modulator, a wavelength selectivity of 0.075 nm is demonstrated together with a uniformity of ±0.2 dB on a tuning range of 2.2 nm corresponding to N = 30 resolvable frequencies. N > 600 could be obtained with an acousto-optic cell specially designed for this device.

In recent years, a significant amount of attention has been drawn towards all-optical semiconductor switching. To that respect, exploitation of light localization, in slow light photonic crystal waveguides (PCWs) or in microcavities, is of considerable interest because it enables enhancement of optical nonlinearities. Recently, we observed experimental and theoretical enhancement of optical Kerr effect, two-photon absorption (TPA) and free-carrier index changes (FCI) in GaAs PCWs, which demonstrated the important role of group velocity [1].

The ability of two-dimensional (2D) photonic crystals (PC) for high enhancements of nonlinear processes is analyzed in the case of a degenerate band edge when two symmetrical diffracted beams are generated by Bragg diffraction in the 2D-PC. Calculations are performed using the very simple Bragg-coupled wave theory which only involves three coupled waves (the incident wave and the two diffracted waves) for the linear interaction. The validity of the approximation is proved for wavelengths lying at the neighborhood of the band edges of 2D-PC. Very large local-field intensities are predicted around the band-edge wavelengths, in particular for the upper band edge. Nonlinear propagation is studied through the analysis of degenerate four-wave mixing. For counterpropagating pump beams orthogonally sent onto the 2D-PC huge improvement of the phase conjugate reflectivity are predicted at least for small incidence angles of the signal beam. These results represent an improvement by a factor of 20 when compared to the case of a one-dimensional PC of the same thickness made of the same materials. As three intense phase conjugate beams are generated in the four-wave mixing interaction, the 2D-PC could be very interesting for the purpose of dense parallel optical signal processing. Moreover, the simple theoretical analysis developed in the paper can be used for any kind of 2D-PC.

International audience; A very simple model has been developed to describe the diffractive properties of a crossed grating structure of the refractive index formed by a thin transmission grating recorded in a Bragg reflector. When the Bragg condition of the transmission grating coincides with the band edge of the reflection grating seen as a one dimensional photonic crystal, the diffraction efficiency and wavelength selectivity of the transmission grating are highly enhanced and a Bragg diffraction regime can be obtained, even in very thin samples. The model can be used to design micrometric very efficient new diffracting devices for optical signal processing

Recent developments in the field of nonlinear optics with photonic crystal fibers have led to the realization of supercontinuum spectra or parametric sources of correlated photons. However the nonlinearities were still limited by the use of silica. Hollow core photonic crystal fibers (HCPCF) filled with highly nonlinear liquids or gases enable the implementation of more performing nonlinear devices and open the scope of potential applications thanks to the large variety of usable liquids and gases. Moreover liquid and gas filled HCPCF present several original propagation properties such as transmission bands that can be tailored to favor or prevent a given nonlinear mechanism. In this work we will show that the on-purpose limited transmission band enables a high conversion efficiency towards a single Stokes component even at high pump intensities. Moreover such Raman converters generate single spatial mode at specific wavelengths that can be determined to fit desired applications.

Nonlinear propagation experiments in GaAs photonic crystal waveguides (PCW) were performed, which exhibit a large enhancement of third order nonlinearities, due to light propagation in a slow mode regime, such as two-photon absorption (TPA), optical Kerr effect and refractive index changes due to TPA generated free-carriers. A theoretical model has been established that shows very good quantitative agreement with experimental data and demonstrates the important role that group velocity plays. These observations give a strong insight into the use of PCWs for optical switching devices., Comment: 6 pages

Non-linear Faraday processes occurring at high laser intensities are experimentally demonstrated in a Cd 0.75 Mn 0.25 Te alloy. Both the polarization direction and the phase of the incident beam are modified through the non-linear interaction. The large non-linear susceptibilities measured for the material show that non-linear Faraday processes overcome two-photon absorption and Kerr effects for magnetic field of the order of few teslas.

Nonlinear Faraday processes occuring at high laser intensities are experimentally demonstrated in a Cd 0.75 Mn 0.25 Te alloy. Both the polarization direction and phase of the incident beam are modified through the nonlinear interaction. The large nonlinear susceptabilities measured for the material show that nonlinear Faraday processes are expected to overcome two-photon absorption and Kerr effects for magnetic field of the order of few Tesla.

An item development effort aimed at measuring aptitudes in (minority and female) subpopulations is described. The project, completed under contract with the U.S. Coast Guard, developed items in the areas of mechanical knowledge and comprehension and arithmetic reasoning. A cross-cultural orientation guided the endeavor. Item development is described and preliminary reliability and validity information is reported. Results are discussed in terms of future considerations to help guide work on item development.