Following the discovery of graphene, a family of two-dimensional materials continues to attract huge scientific interest, with most of the focus being on optoelectronic applications of their single-atomic layers. It is less known, however, that bulk layers of transition metal dichalcogenides have a higher refractive index than silicon and exhibit giant optical anisotropy. We discuss how these properties allow one to design photonic integrated circuits with a higher density of integration thanks to weaker waveguide crosstalk and lower bending losses.

We present a modal method for calculating the optical Kerr effect in layered photonic nanostructures. An example of optical Kerr effect exaltation is shown on a coupled nano-Fabry-Perot structure.

We demonstrate that, by varying the thickness of the dielectric spacer in a three-layermetamaterial absorber, we can tune the spectral absorbance across the whole visiblespectrum. This effect arises due to the excitation and enhancement of propagatingsurface plasmons, and localized surface plasmons. These results are beneficial forapplications including solar power generation and those that require selective absorp-tion.

The paper presents an extensive numerical analysis performed by 3D-simulations using the FDTD method to identify the optimal configuration of the nano-antennas that constitute a plasmonic metasurface. The aim was to achieve the highest resonance for local enhancement of the excitation field and collection efficiency of emitted photons. We investigated different metals, shapes and geometrical parameters for the nano-resonators composing the metasurface. The best results for Rhodamine 6G excitation and emission were obtained using silver cylindrical resonators with 105 nm diameter in a rectangular array, and with 110 nm long U-shape.

Graphene plasmon polaritons(GPPs) have attracted great interest over the past decade owing to its electrical and optical properties, such as electrically tunable property, extreme confinement, ultrabroad tuning spectrum, and low intrinsic loss. However, these properties are degraded when graphene is placed on top a substrate such as silicon dioxide, limiting its potential applications. Here, we demonstrate a sub-wavelength periodic W-shaped structure that shapes graphene, leading to an enhancement of the GPPs optical properties.

The control of thermal radiation is a crucial factor in reaching higher efficiency in various energy applications. Here, we present a metamaterial with a sharp transition from a high emissivity to a very low emissivity. The metamaterial has an easy-to-fabricate and customizable multilayer structure, which allows to maximize the thermal emission in the region of the desired wavelengths. The structure is being developed for Thermo-Photovoltaic (TPV) and energy storage applications, therefore the materials involved in the design must be thermally stable. The designed multilayer shows very promising results.

In evacuated flat plate solar collectors, thanks to the high vacuum insulation, the main loss mechanism is only represented by radiative losses from the selective absorber. Radiative losses incidence on the performances of the collector increases with increasing temperature. Low emissivity thin film coatings on an Aluminium bulk substrate could improve the coating performances by reducing its thermal emittance, keeping the economic advantages of using a substrate as cheap and light as Aluminium.

We propose an optical gating experiment to study the dynamics of nanolasers taking advantage of nonlinear interactions (FWM) in a dispersion-shifted fiber (DSF). This constitutes a new methodology to study an extremely fast (10 ps – 20 ps) and weak response (~ µW peak power) of nanolasers emission when

pumped by a very short light pulse on the order of ~ 250 fs. In this work, we aim to study the temporal properties of 1.55μm InGaAs/InP 1D photonic crystal lasers operating at room temperature.

In this paper, we report the investigation of optical parametric oscillations using nonlinear photonic crystals of periodically poled LiTaO3 (PPLT). We point-out the generation of two pairs of signal and idler (OPO1 and OPO2) in the same nonlinear photonic crystal. It is found that the second pair OPO2 appears with different quasi-phase matching conditions induced by a local refractive index variation. Our analysis indicates that this index variation results from a competing effect between quadratic cascading and electro-optic induced refractive index changes

We study a certain class of eigenstates of the two-dimensional nonlinear Schrödinger equation with focusing Poisson and cubic nonlinearities. The states take the form of self-trapped vortex rings endowed with azimuthal phase. For each value of the topological charge l, there is a parameter-dependent family of solutions that are linked to the relative importance of the cubic term. Remarkably, certain vortex rings break down due to linear instabilities but the nonlinear evolutions leads to the reconstruction of the initial profile resembling the well-known Fermi-Pasta-Ulam-Tsingou-like recurrence.

Multiple four-wave-mixings can be used to improve the efficiency of a spontaneously generated Stokes and antiStokes photon pair via a symmetric level configuration that exhibits dark-state trapping. Preliminary results in atomic interfaces show that photon pair generation can be achieved while being absorption and hampering gain effects largely suppressed. Extensions to solid interfaces are also envisaged.

Design and the implementation of a femtosecond Stimulated Raman Scattering microscope, equipped with three femtosecond laser sources. A Titanium-Sapphire, an optical parametric oscillator, and a second harmonic generator is presented. Our microscope is designed in such a manner that it can cover all the regions of Raman spectra, taking advantage of two possible laser combinations. The first, TiSa and OPO laser beams, which cover the CH region or O-H region in stimulated Raman gain modality, whereas the second, TiSa and SHG laser beams, covers the CH region and the fingerprint region.

Autocorrelation is important because they allow monitoring the pulse duration and chirp of the laser beam, which are a fundamental parameter to optimize the nonlinear light matter interaction in microscopy. In this paper, we investigate the two laser sources. In our case, a femtosecond Ti:Sapphire oscillator and a femtosecond synchronized optical parametric oscillator is characterized by non-linear interferometric measurements. Taking advantage of two-photon absorption, autocorrelation measurements of each laser beam are carried out. Results are reported and discussed.

We report on multiplexing several Fabry-Perot (FP) cavities in single-mode optical fibers for high-precision spatially resolved sensing of refractive indices (RI) of liquids. Resonators are fabricated by cutting small slots into fibers using a diamond-blade dicing saw and additionally coated with thin Ta2O5 layers to increase cavity reflectance. The multiplexing performance, temperature compensation ability and accuracy of the fabricated sensors with up to four open cavities were tested on sucrose solutions over a range of temperatures.

A CPC system embedded in a high vacuum thick envelope and an evacuated flat plate solar collector are compared. Multilayer absorber coatings based on a Cr2O3/Cr/Cr2O3 tri-layer structure have been optimized to work at 573 K for both solutions, maximizing the efficiency.

We report on the simulation of reflectance and transmittance spectra taken on a set of non-continuous gold nanoparticles thin film deposited on sodium alginate.

The spectra are simulated by means of the Generalized Transfer Matrix method, using the Lorentz oscillator model, by taking into account that the optical function of nanostructured gold exhibits reduced relaxation time. The localized surface plasmon is simulated through a dedicated oscillator.

The experimental results are well reproduced by the applied model. We show that an in-plane coalescence occurs for film thicknesses larger than 5 nm.

We report our achievements with blue diode pumped Ti:sapphire fs oscillators and amplifiers. SESAM modelocked oscillator generated 460 mW output power and 65 fs pulses at 90 MHz and was used for multiphoton microscopy. Kerr-lens modelocked oscillator features broadbandwidth of 71 nm with output power of 300 mW, suitable for OCT. Our simulations predict that up to 20% small signal gain should be feasible for amplifier with 40 W pumping. Preliminary measured 4% single-pass gain with 10 W pumping is promising for room temperature Ti:sapphire amplifier.

We perform multifocus hybrid fs/ps-CARS spectroscopy applied to gas phase diagnostics and hyperspectral microscopy. The scheme is first used to record single shot N2 CARS spectra from two spots that are 3 mm apart in ambient air and perform simultaneous 1 kHz temperature follow-up in the vicinity of a flame. Then 2-point-CARS simultaneous spectroscopy is performed within a microscope in liquid toluene with 38 µm separation between the two laser spots. It demonstrates how to increase the amount of spatial information retrieved by CARS spectroscopy at minimum laser energy cost.

Interaction of femtosecond laser pulses with metallic tips have been studied extensively and they have proved to be a very good source of ultrashort electron pulses. We present our study of interaction of Laguerre-Gaussian (LG) laser modes with Tungsten tips. We report a change in the order of the interaction for LG beams and the difference in the order of interaction is attributed to ponderomotive shifts in the energy levels corresponding to the enhanced near field intensity supported by numerical simulations.

We discuss the relevance of the amplified spontaneous emission (ASE) as well as the pulse picking process for carrier-envelope phase (CEP) stability of high-power ytterbium-doped fiber few-cycle laser systems. The front-end of the laser system that generates 5.8 fs pulses with an energy of 1.1 mJ at a repetition rate of 100 kHz is optimized to significantly reduce the level of white phase noise and achieve an improvement of the integrated CEP noise from 620 to 260 mrad for Fourier frequencies ranging from 2 kHz to 50 kHz.

We report the generation of an octave spanning supercontinuum (SC) from 800~nm to 2800~nm in 20 cm multimode graded-index fiber made of lead-bismuth-gallate glasses. We study the SC generation as a function of pump wavelength both in normal and anomalous dispersion regime of the fiber. For specific light injection conditions, we further observe signatures of beam self-cleaning dynamics into the low-order LP01 and LP11 modes. This is the first demonstration of SC generation in a non-silica multimode gradient-index fiber, opening novel perspectives for producing broadband, high-power SC in the mid-infrared.

We report on a versatile source for NIR and MIR applications employing an OPO/DFG system to downconvert 1 µm radiation to 1.3 .. 19 µm (7700 .. 527 cm−1). Broadband emission is achieved over the whole tuning range while spectral focusing allows to significantly reduce bandwidths below 2200 cm−1 if required.

We present a novel optical arrangement that introduces arbitrary angular dispersion profiles into optical pulses, and is thus capable of independently tuning the magnitude and sign of all dispersion orders. Using this universal angular-dispersion synthesizer we isolate individual dispersion orders and modify their magnitude and sign up to fourth order. Moreover, we produce controlled superpositions of multiple dispersion orders, thereby producing dispersion profiles observed in optics for the first time. This breakthrough may be useful for new forms of phase and group-velocity matching in nonlinear optical interactions.

We show the preliminary results of cavity ring-down spectroscopy based on a near-infrared frequency comb source and retrieve the multiplexed decays using a time-resolved fast-scanning Fourier transform spectrometer. We use a cavity with a moderate finesse to detect the absorption spectrum of the laboratory air.

We demonstrate a new approach for stray light characterization of optical instruments, based on ultrafast time-of-flight imaging. A pulsed laser source and a streak camera is used to record and identify individual stray light contributors, taking advantage of the fact that each stray light path has its own optical path length and therefore arrives at the focal plane at a specific time. This method will allow to better understand the origin of stray light, thus rendering more straightforward improvement of the instrument by re-design or processing.

We report numerical simulation results investigating laser starting dynamics of a compact all-PM fiber oscillator based on a nonlinear amplifying loop mirror (NALM). Depending on the initial starting conditions of the oscillator, the final steady state is reached through different paths via a competition between CW lasing and pulsing. The simulation shows that establishing stable CW lasing before pulse build-up in the oscillator cavity can prevent strong peak-power transients during startup. The transition from CW lasing to stable pulsing can be is achieved smoothly from noise by increasing the pump power.

We discuss the state of the art, the ongoing research and development, and the potential for achieving a supra-terawatt peak power in few-cycle pulses at a long-wave infrared wavelength with a laser system based on high-pressure, mixed-isotope CO2 amplifiers.