This PDF file contains the front matter associated with SPIE Proceedings Volume 8071, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

The near-IR light absorption oscillations in 2D macroporous silicon structures with microporous silicon layers, CdTe surface nanocrystals and SiO₂ nanocoatings are investigated. The electro-optical effect was taken into account within the strong electric field approximation. Well-separated oscillations with giant amplitude were observed in the spectral ranges of surface level absorption. This process is because of resonance electron scattering on the surface impurity states with the difference between two resonance energies equal to the Wannier-Stark ladder due to big scattering lifetime as compared to the electron oscillation period in an electric field. The electron transitions and free electron motion are realized due to additional change of local electric field as a result of grazing light incidence and quasi-guided mode formation.

The aim of this work is to compare advantages and disadvantages of different techniques for coupling a mini-discoptical- resonator to determine quality factor of its resonance. Optical fiber coupled to a resonator consists in a mini disc with whispering gallery modes at its circumference. We choose to work with three materials and design compact miniresonators. Fused silica is found to be suitable for these applications thanks to its hardness in the range 6-7 and the behavior to mechanical shocks, despite its sensitivity to water pollution. With its tetragonal crystal and a good behavior with risk of water pollution, Calcium fluoride is a good candidate despite sensitivity to mechanical shocks. Magnesium fluoride is the third material used. As a critical step, taper coupling is set with a 20nm resolution positioning system. Miniresonator is excited from a system equipped with a tunable laser diode with a tunability from 1490 to 1640 nm and a linewidth narrower than 300kHz. Light is coupled into the microsphere either from glass or fiber prism or with fiber taper via evanescent field. We have also used a single frequency 660nm laser diode with a linewidth narrower than 100kHz which can be tuned about 10pm to test a single resonant peak. Both sources are used with either a tapered fiber or a filed fiber. Resonance is observed and quality factor of the resonators is found to be in the range of 10⁸.

Stochastic quasi-phase-matching of the process of spontaneous parametric down-conversion is analyzed. It is shown that spectral, temporal and spatial properties of photon pairs generated in randomly poled crystals are similar to those generated in chirped periodically-poled crystals. Especially, randomly poled crystals are capable to emit photon pairs with ultra-broad spectra.

In this paper we construct the solution of nonlinear Schrödinger equations, describing the three-wave interaction in medium with combined (cubic and quadratic) nonlinear response under the condition of long pulse duration and plane wave approximation. The main feature of applied approach concludes in using of Hamiltonian of the equations set to find the algebraical equation with respect to difference of phases of interacting waves without the solution of the corresponding differential equation. For three-wave interaction we write the integral which depends on mismatching of wave-vectors and on input intensities of interacting waves. The evolution of intensity of each wave is express by the elliptical function.

In the present paper we consider a simultaneous propagation of two weak pulses (the 'probe' and 'trigger') in the tripod configuration atomic medium, irradiated by a strong quasi-standing control field. The latter leads to a periodic modulation of the refractive index of the medium which now becomes a photonic crystal. While propagating in such a medium both probe and trigger are split into transmitted and reflected components the nonlinear phase shifts of which are of particular interest. We calculate the nonlinear periodic susceptibilities and make numerous simulations of the propagation of the stationary pulses in different conditions. We calculate the phases of the outgoing fields and find the optimal values of parameters characterizing the system, i.e. when the nonlinear phase shifts of both transmitted and reflected probe and trigger components are large. We show a convenient way of controlling the process by shifting the frequency of the incoming probe. We plot the transmission and reflection spectra for different values of parameters of the system, which could be used as a flexible beam splitter, for which the phases and intensities of outgoing beams can be independently changed.

Lithium Niobate (LN) based electro-optic modulators are well known in the optical communications field, due to their high bandwidth and deep rejection ratio [1]. These performances could be used in the field of astronomy for stellar interferometry in the mid-infrared domain [2]. With our partners from Photline Technologies, we have conceived, developed and characterized a 2T ABCD [3] beam combiner in the near-infrared (1.5μm, the H-band in astrophysics). The modulation scheme, presented below in Figure 1, allows to determine the fringe characteristics in a single shot measurement, without the need to externally scan the optical phase delay. Fine adjustment of the relative phase can be achieved using the electro-optic properties of the lithium niobate waveguides. In particular, the phase on each output can be electrically controlled and locked by using appropriate electrodes. These devices have to ensure modal filtering to reject optical aberrations of the wavefront and thus optimize the fringes contrast, which means that they have to be single mode through all the spectral range of interest. This also means that the couplers should be achromatic and balanced in order to optimize the fringe contrast. We will present results on global transmission, performance of the couplers and the electro-optic behavior of the device using monochromatic as well as wide spectral sources in the H-band.

Nature has developed sophisticated methods to create structure-based colors as a way to address the need of a wide variety of organisms. This pallet of available structures presents a unique opportunity for the investigation of new photonic crystal designs. Low-temperature sol-gel biotemplating methods were used to transform a single biotemplate into a variety of inorganic oxide structures. The density of optical states was calculated for a diamond-based natural photonic crystal, as well as several structures templated from it. Calculations were experimentally probed by spontaneous emission studies using time correlated single photon counting measurements.

Attosecond XUV pulses (80 as, 1 as = 10^-18 s [1, 2]) together with phase-stabilized few-cycle (few-femtosecond) laser pulses [3] used for their generation have enabled the development of a technique for attosecond sampling of electrons ejected from atoms or molecules [4, 5]. After the generation of attosecond pulses on a daily base and their characterization at high precision has been made possible, the dynamics of the photoionization process on solids has been studied [6]. Not only that attosecond metrology now enables clocking on surface dynamics, but also the individual behaviour of electrons of different type (core electrons vs. conduction band electrons) can be resolved. Here, we measured a time delay of about 100 as on the emission of the aforemention two types of electrons. The information gained in these experiments may have influence on the development of many modern technologies including semiconductor and molecular electronics, optoelectronics, information processing, electrochemical reactions, etc..

We review recent advances in the generation of isolated attosecond pulses, produced by using the process of high-order harmonic generation in gases. In particular we report on a novel technique, based on the production of a temporal gate obtained exploiting sub-cycle ionization dynamics of the neutral atom population. Isolated attosecond pulses with time duration of 155 as and an energy on target of 2.1 nJ were generated and fully characterized. Such isolated pulses can be used in attosecond pump-probe experiments to study ultra-fast electronic dynamics in atoms and molecules with attosecond temporal resolution.

We take advantage of the Raman soliton self-frequency shift experienced during the propagation in an anomalous dispersive photonic crystal fiber in order to continuously tune the central frequency of ultrashort pulses. We discuss the fiber properties to be favored to obtain high power spectral densities and we carry out an extensive experimental study of the properties of the frequency shifted pulses in terms of spectral, autocorrelation, and RF spectrum measurements.

The properties of NPC structures in strontium tetraborate are analyzed. Different types of NPC structures are revealed that possess different nonlinear properties, and their spectral dependences of frequency conversion efficiency are calculated and compared. Experimental study of these structures is reported for the process of doubling of the second harmonic of fs Ti:S laser. Tuning of generated radiation is obtained in the range 187.5 - 232.5 nm, with extreme insensitivity to the angular orientation of NPC. Behavior of tuning curve along investigated fundamental wave range is similar in all studied samples, but efficiency obtained depends on the type of structure. Conversion efficiency and spectral quality of generated radiation is experimentally shown to grow better when using NPC with improved structure. Prospects of VUV converter on a single NPC are discussed. NPCs of SBO are demonstrated to be useful for autocorrelation diagnostics both in random QPM geometry and in the geometry of nonlinear diffraction from virtual beam.

We analyse the group velocity of a laser pulse in an optically dressed atomic system. A Λ system with an additional close upper level and an incoherent pump is specially investigated. The group velocity of a pulse is strongly dependent on the optical properties of the system which can be modified by changing the amplitude or detuning of a strong coupling field or of an incoherent pump between the two lower levels of the system. Depending on the parameters, the medium may have alternatively absorptive or gain properties and the dispersion can be changed from anomalous into a normal one. The ranges of parameters are especially investigated in which absorption (gain) is not too strong, with dispersion being not too steep. The group velocity of a pulse propagating through a sample with such optical properties can be switched from the subinto superluminal regime. The dynamics of propagation in the case of negative group velocities of a small absolute value is especially interesting. In such a regime the peak of the transmitted pulse exits the sample before the peak of the incoming pulse reaches the medium. The transmitted pulse splits into two pulses - one of them propagates forward behind the medium and the other propagates backward and is cancelled at the entrance of the sample by the incoming pulse. Ranges of parameters are seeked in which the shape of the pulse is changed and the group velocity as a single parameter is not sufficient to describe the pulse propagation.

In this work, we investigate experimentally second-harmonic generation (SHG) of pulsed near-infrared (NIR) diode laser radiation in a nonlinear crystal with a ridge waveguide structure. Pulses at 1064 nm with a pulse energy of 560 pJ, a peak power of 3.2 W and a pulse length of 138 ps are generated at a repetition rate of 10 MHz by a monolithic DFB (Distributed Feedback) tapered MOPA (Master Oscillator Power Amplifier). For frequency doubling, a periodically poled MgO-doped lithium niobate crystal with a ridge waveguide structure is used. During SHG, a dependence of the second-harmonic (SH) pulse duration on the NIR pulse energy as well as a distinctive influence of the waveguide structure on the beam quality is observed. A maximum SH peak power at 532 nm of 0.75 W and an opto-optical conversion efficiency of 24 % are achieved. Furthermore, an influence of the spectral distribution of the NIR laser radiation on the SHG conversion efficiency is observed.

In this paper we describe recent progress in the study of scale-free optical propagation in super-cooled nonergodic ferroelectrics. Our experimental and theoretical findings indicate that a regime can be found in which diffusion-driven photorefractive effects can fully annul the diffraction of focused laser beams. This demonstrates that diffraction can be systematically eliminated from an optical system and not simply compensated, with fundamental implications for optical imaging and microscopy. The effect transfers directly from the paraxial regime into the non-paraxial regime described by the Helmholtz Equation, and suggests a means to achieve the propagation of super-resolved optical images. The result is a nonlinear-based metamaterial, even though the underlying nano-structuring of the ferroelectric is random and the effect is both non-absorptive and wavelengthindependent for a wide spectrum.

In this work we study the photorefractive and electro-optical properties of Zirconium-doped congruent lithium niobate (LN) crystals. In order to set the ground for the utilization of these crystals in nonlinear wavelengthconversion devices, we investigate the dependence of the photorefractive properties of the crystals on dopant concentration and incident power. In our experiments the birefringence variations induced by a 532-nm laser beam are measured by using the Sénarmont method, in the ZrO₂ concentration range 0-3mol% and intensity range 155- 1800 W/cm². In order to investigate photorefractivity at high intensities, we have also utilized the direct observation of the distortion of the light spot transmitted by the crystal. In presence of photorefractivity, the transmitted light spot becomes smeared and elongated along the c-axis. Our data show that the threshold ZrO₂ concentration can be in the range 2.5-3mol%. Considering that the growth of large homogeneous Zr:LN crystals should be easier than for Mg:LN, and that electrical poling of these crystals has already been demonstrated, Zr-doped LN could represent a more convenient choice than Mg:LN for the realization of room-temperature wavelength converters.

Second-harmonic generation (SHG) and electro-optic (EO) modulation were studied on thermally poled twin-hole fiber. Metal electrode wires were inserted into the side holes. The typical poling condition was 2.5 kV, 300 °C, and 40 min. SHG was measured using a Q-switched Nd:YAG laser. The SH power did not depend on the applied forward or reverse voltages. SHG without poling was also measured, then the maximum power was about 1/18 that of the poled SHG. EO modulation was performed using a twin-hole fiber inserted to a fiber-optic Mach-Zehnder interferometer. An AC modulation voltage was applied to the electrodes together with a DC bias voltage. Without poling, the modulation output was obtained only when a DC bias voltage was applied simultaneously. After poling, a modulation output was obtained without any bias voltage, and for the forward DC bias the modulation output increased with the bias voltage. For the reverse DC bias the modulation output showed the minimum for a bias voltage. The origin of the second-order nonlinearities and the other effects in the above SHG and EO modulation are discussed considering charge layers.

Generation of two-photon light with given spectral and temporal properties is of great interest for quantum communication and quantum metrology applications. In particular, preparation of biphotons with ultra-narrow correlation time is a very important task. In a recent series of papers, our group analyzed the generation of twophoton wavepackets, produced by Spontaneous Parametric Down Conversion, in crystals with linearly chirped quasi-phase matching grating. Wavepackets present very broad spectra but a broad spectrum does not necessarily imply small correlation times, although the inverse is true. Indeed, the spectrum broadening induced by the grating is inhomogeneous; for this reason, the two-photon spectral amplitude present a phase (a frequency chirp) that depend nonlinearly on the frequency. Hence, the two-photon wavepackets are not Fourier transform-limited. As suggested in, the ideal way to make the wavepacket perfectly transform limited is to insert in the path of the biphotons a proper optical medium that compensates the non-linear part of the phase factor present in the spectral amplitude. In our work, we investigate the non-local temporal compression of the photons induced by the insertion of a standard optical fibre in the path of one of the two photons. We present and discuss a systematic study of this phenomenon and some optimal situation where the full numerical calculation shows an effect that can be clearly observed with a realistic set-up. The study has open the way to the practical realization of this idea.

The purpose of this paper is to investigate the scattering by a nonlinear crystal whose depth is about the wavelength of the impinging field. More precisely, an infinite nonlinear slab is illuminated by an incident field which is the sum of three plane waves of the same frequency, but with different propagation vectors and amplitudes, in such a way that the resulting incident field is periodic. Moreover, the height of the slab is of the same order of the wavelength, and therefore the so-called slowly varying envelope approximation cannot be used. In our approach we take into account some retroactions of the scattered fields between them (for instance, we do not use the nondepletion of the pump beam). As a result, a system of coupled nonlinear partial differential equations has to be solved. To do this, the finite element method (FEM) associated with perfectly matched layers is well suited. Nevertheless, when using the FEM, the sources have to be located in the meshed area, which is of course impossible when dealing with plane waves. To get round this difficulty, the real incident field is simulated by a virtual field emitted by an appropriate antenna located in the meshed domain and lying above the obstacle (here the slab).

Periodic media offer impressive opportunities to manipulate the transport of classical waves namely light or sound. Elastic waves can scatter light through the so-called acousto-optic interaction which is widely used to control light in telecommunication systems and, additionally, the radiation pressure of light can generate elastic waves. Concurrent control of both light and sound through simultaneous photonic-phononic, often called phoxonic, bandgap structures is intended to advance both our understanding as well as our ability to manipulate light with sound and vise versa. In particular co-localization of light and sound in phoxonic cavities could trigger nonlinear absorption and emission processes and lead to enhanced acousto-optic effects. In the present communication, we present our efforts towards the design of different phoxonic crystal architectures such as three-dimensional metallodielectric structures, two-dimensional patterned silicon slabs and simple one-dimensional multilayers, and provide optimum parameters for operation at telecom light and GHz sound. These structures can be used to design phoxonic cavities and study the acousto-optic interaction of localized light and sound, or phoxonic waveguides for tailored slow light-slow sound transport. We also discuss the acousto-optic interaction in onedimensional multilayer structures and study the enhanced modulation of light by acoustic waves in a phoxonic cavity, where a consistent interpretation of the physics of the interaction can be deduced from the time evolution of the scattered optical field, under the influence of an acoustic wave.

The performance advances in communication systems like Radar system, precision navigation, space application and time and frequency metrology require more stable frequency and low phase noise system. Here is presented a configuration of phase noise measurement system operating in X- band using a photonic delay line as a frequency discriminator. This system doesn't need any excellent frequency reference and works for any frequency between 8.2 and 12.4 GHz. Using cross correlation on 500 averages, noise floor of the instrument is respectively -150 and -170 dBc/Hz at 10¹ and 10⁴ Hz from the 10 GHz carrier (-90 and -170 dBc/Hz including 2 km delay lines). This instrument is developed in the context of association with the national french metrology institute (laboratoire national de métrologie et d'essais, LNE). This calibration system is to be integrated in measurements means of the accredited laboratory to improve the Calibration Metrology Capabilities (CMC) of the LNE.

The dynamics of an ionization and a recombination in an ultrastrong laser field is studied by ab initio numerical simulations performed for a realistic atomic system in the regime of attosecond laser pulse duration. In particular the stabilization phenomenon is studied, the presence of which is confirmed in 3D. We first describe the method of integrating the Schrödinger equation (in general parabolic equations) which we adopt, taking advantage of the axial symmetry of the studied system and uses the FFT and Chebyshev polynomials (FCP) method. Further we present its implementation based on the CUDA technology to benefit from the power of graphics cards.

We describe a parallel multi-threaded approach for high performance modelling of wide class of phenomena in ultrafast nonlinear optics. Specific implementation has been performed using the highly parallel capabilities of a programmable graphics processor.

Wavelength tunable synchronous pulse sources are highly desirable for spectroscopy and optical diagnostics. The common method to generate short pulses in the fiber is the use of nonlinear induced spectral broadening which result in soliton shaping in anomalous dispersion regime. However, to generate ultra-short pulses, broadband gain mechanism is also required. In recent years, Raman fiber lasers have retrieved strong interest due to their capability of serving as pump sources in gain-flattened amplifiers for optical communication systems. The fixed-wavelength Raman lasers have been widely studied in the last years, but recently, much focus has been on the multi wavelength tunable Raman fiber lasers which generate output Stokes pulses in a broad wavelength range by so called cascaded stimulated Raman scattering. In this paper we investigate synchronous 1st and 2nd order pulsed Raman lasers that can achieve frequency spacing of up to 1000cm-1 that is highly desired for CARS microscopy. In particular, analytical and numerical analysis of pulsed stability derived for Raman lasers by using dispersion managed telecom fibers and pumped by 1530nm fiber lasers. We show the evolution of the 1st and 2nd order Stokes signals at the output for different pump power and SMF length (determines the net anomalous dispersion) combinations. We investigated the stability of dispersion managed synchronous Raman laser up to second order both analytically and numerically. The results show that the stable 2nd order Raman Stokes pulses with 0.04W to 0.1W peak power and 2ps to 3.5ps pulse width can be achieved in dispersion managed system.

Erbium-doper fiber (EDF) is a flexible and promising model medium for investigation of the slow/fast light propagation in saturable optical materials. The experiments are usually performed in the spectral range 1480-1570 nm of the absorption/gain of Er3+ ions using the input power of a sub-mW scale. Conventional experimental configuration allows one to observe, however, the input and the output pulse profiles only. We report an original nondestructive technique for observation of a spatial propagation of the pulses via observation of the transient fluorescence excited by the propagating light-pulses at the fiber side, from which we are able to reconstruct how does the fractional delay and the amplitude of the propagating pulses change along the fiber. Results of a numerical simulation of the nonlinear pulse propagation performed for a saturable two-level medium in low contrast approximation proved to be in a reasonable agreement with the experimental observations.