Characterization and performance of the Apollon short-focal-area facility following its commissioning at 1 PW level

We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility(located in Saclay,France),which was performed with the first available laser beam(F2),scaled to a nominal power of 1 PW.Under the conditions that were tested,this beam delivered on-target pulses of 10 J average energy and 24 fs duration.Several diagnostics were fielded to assess the performance of the facility.The on-target focal spot and its spatial stability,the temporal intensity profile prior to the main pulse,and the resulting density gradient formed at the irradiated side of solid targets have been thoroughly characterized,with the goal of helping users design future experiments.Emissions of energetic electrons,ions,and electromagnetic radiation were recorded,showing good laser-to-target coupling efficiency and an overall performance comparable to that of similar international facilities.This will be followed in 2022 by a further commissioning stage at the multipetawatt level.

Highly Angular Tolerant Transmission Filters for Narrow-Band Image Sensors

A dielectric transmittance filter composed of subwavelength grating sandwiched between two few-layers distributed Bragg reflectors (DBRs) is proposed with the aim of being compatible with CMOS technology and to be tunable by lithographic means of the grating pattern without the need of thickness changes, in the broad spirit of metamaterials. The DBR mirrors form a Fabry-Perot (FP) cavity whose resonant frequency can be tuned by changing the effective refractive index of the cavity, here, by tailoring the in-plane filling factor of the grating. The structure has been studied and designed by performing numerical simulations using Fourier Modal Method (FMM). This filter proves to have high broad angular tolerance up to ±30˚. This feature is crucial for evaluating the spectral performance of narrow-band filters especially the so-called Ambient light sensors (ALS). By analyzing the transmittance spectral distributions in the band diagram, it is found that the angular tolerance is due to coupling between the FP and the guided mode inside the cavity in analogy to resonances occurring within multimode periodic waveguides in a different context.

Optimization of Parameters CO<SUB>2</SUB>Laser for Drilling Different Types of Glass

The aim of this work is to study in detail the drilling process on glass by CO2 laser. The study parameters considered in the present experiments are based on the laser beam power of range (30% - 80% of 25 W) and an exposure time for drilling (2 - 8 s). The measured diameters of holes by optical methods are between [300 - 800 μm]. The results obtained by optical observations suggest that ordinary and mineral glasses cannot withstand to a contact of the laser beam and crack during the formation of the drilling hole. The minimum power and duration of exposure are the optimal parameters for drilling the organic glass, we observe no micro-cracks, and again we see that the edges of the holes have a good surface quality with a high aspect ratio.

Design of a Multimodal Light Sheet Optical System for Multivariate Applications in Phytopathology

The design of optical instruments is an active subject due to improvement in lens techniques, fabrication technology, and data handling capacity. Much remains to do to expand its application to phytopathology, which would be in particular quite useful to improve crop growth monitoring in countries like Mali. An optical multimodal system for plant samples has been developed to improve the characterization of leaf disease symptoms, provide information on their effects, and avoid their spread. Potentially inexpensive components (laser, lens, turntables camera and sample, filter, lens, camera and computer) have been selected, assembled and aligned on an optical table into a multimodal system operating in transmission, reflection, diffusion and fluorescence. The illumination and observation angles can be adjusted to optimize viewing conditions in the four modes. This scientific contribution has been an initiation into the design and implementation of an optical instrument. Initial results are shown and will now be extended in cooperation with agronomic laboratories in African countries for tests on specific plant diseases in relation with prevailing climate conditions.

Effects of Interactions and Temperature in Disordered Ultra-Cold Bose Gases

We simulate ultra-cold interacting bosons in quasi-one-dimensional, incommensurate optical lattices. In the tight-binding limit, these lattices have pseudo-random on-site energies and thus can potentially lead to Anderson localization. We use the Hartree-Fock-Bogoliubov formalism in the Bose-Hubbard model to explore the parameter regimes that lead to exponential localization of the ground state in a 3-colour optical lattice and investigate the role of repulsive interactions, harmonic confinement and finite temperature.

Synchronized off-harmonic probe laser with highly variable pulse duration for laser-plasma interaction experiments

This paper presents the development and experimental utilization of a synchronized off-harmonic laser system designed as a probe for ultra-intense laser±plasma interaction experiments. The system exhibits a novel seed-generation design,allowing for a variable pulse duration spanning over more than three orders of magnitude, from 3.45 picoseconds to 10 nanoseconds. This makes it suitable for various plasma diagnostics and visualization techniques. In a side-view configuration, the laser was employed for interferometry and streaked shadowgraphy of a laser-induced plasma while successfully suppressing the self-emission background of the laser±plasma interaction, resulting in a signal-to-self-emission ratio of 110 for this setup. These properties enable the probe to yield valuable insights into the plasma dynamics and interactions at the PHELIX facility and to be deployed at various laser facilities due to its easy-to-implement design.

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

We analyse the resonant mode structure and local density of states in high-Q hybrid plasmonic-photonic resonators composed of dielectric microdisks hybridized with pairs of plasmon antennas that are systematically swept in position through the cavity mode.On the one hand,this system is a classical realization of the cooperative resonant dipole–dipole interaction through a cavity mode,as is evident through predicted and measured resonance linewidths and shifts.At the same time,our work introduces the notion of‘phased array’antenna physics into plasmonic-photonic resonators.We predict that one may construct large local density of states(LDOS)enhancements exceeding those given by a single antenna,which are‘chiral’in the sense of correlating with the unidirectional injection of fluorescence into the cavity.We report an experiment probing the resonances of silicon nitride microdisks decorated with aluminium antenna dimers.Measurements directly confirm the predicted cooperative effects of the coupled dipole antennas as a function of the antenna spacing on the hybrid mode quality factors and resonance conditions.

Enhanced second-harmonic generation from two-dimensional MoSe_(2) on a silicon waveguide

Two-dimensional transition-metal dichalcogenides(TMDCs)with intrinsically broken crystal inversion symmetry and large secondorder nonlinear responses have shown great promise for future nonlinear light sources.However,the sub-nanometer monolayer thickness of such materials limits the length of their nonlinear interaction with light.Here,we experimentally demonstrate the enhancement of the second-harmonic generation from monolayer MoSe_(2) by its integration onto a 220-nm-thick silicon waveguide.Such on-chip integration allows for a marked increase in the interaction length between the MoSe_(2) and the waveguide mode,further enabling phase matching of the nonlinear process.The demonstrated TMDC–silicon photonic hybrid integration opens the door to second-order nonlinear effects within the silicon photonic platform,including efficient frequency conversion,parametric amplification and the generation of entangled photon pairs.

Design and current progress of the Apollon 10 PW project

The objective of the Apollon project is the generation of 10 PW peak power pulses of 15 fs at 1 shot/minute. In this paper the Apollon facility design, the technological challenges and the current progress of the project will be presented.

Dual-color deep-tissue three-photon microscopy with a multiband infrared laser

Multiphoton microscopy combined with genetically encoded fluorescent indicators is a central tool in biology.Threephoton(3P)microscopy with excitation in the short-wavelength infrared(SWIR)water transparency bands at 1.3 and 1.7μm opens up new opportunities for deep-tissue imaging.However,novel strategies are needed to enable in-depth multicolor fluorescence imaging and fully develop such an imaging approach.Here,we report on a novel multiband SWIR source that simultaneously emits ultrashort pulses at 1.3 and 1.7μm that has characteristics optimized for 3P microscopy:sub-70 fs duration,1.25 MHz repetition rate,and μJ-range pulse energy.In turn,we achieve simultaneous 3P excitation of green fluorescent protein(GFP)and red fluorescent proteins(mRFP,mCherry,tdTomato)along with third-harmonic generation.We demonstrate in-depth dual-color 3P imaging in a fixed mouse brain,chick embryo spinal cord,and live adult zebrafish brain,with an improved signal-to-background ratio compared to multicolor twophoton imaging.This development opens the way towards multiparametric imaging deep within scattering tissues.

Hybrid silicon slotted photonic crystal waveguides:how does third order nonlinear performance scale with slow light?

We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption(TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slow-down factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index(n_G) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from n_G=10 to n_G=50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics.

Extreme multiexciton emission from deterministically assembled single-emitter subwavelength plasmonic patch antennas

Coupling nano-emitters to plasmonic antennas is a key milestone for the development of nanoscale quantum light sources.One challenge,however,is the precise nanoscale positioning of the emitter in the structure.Here,we present a laser etching protocol that deterministically positions a single colloidal CdSe/CdS core/shell quantum dot emitter inside a subwavelength plasmonic patch antenna with three-dimensional nanoscale control.By exploiting the properties of metal–insulator–metal structures at the nanoscale,the fabricated single-emitter antenna exhibits a very high-Purcell factor(>72)and a brightness enhancement of a factor of 70.Due to the unprecedented quenching of Auger processes and the strong acceleration of the multiexciton emission,more than 4 photons per pulse can be emitted by a single quantum dot,thus increasing the device yield.Our technology can be applied to a wide range of photonic nanostructures and emitters,paving the way for scalable and reliable fabrication of ultracompact light sources.

All inkjet-printed perovskite-based bolometers

We show flexible bolometer devices produced entirely using digital inkjet printing on polymer substrates.The bolometers consist of a silver interdigital electrode thermistor covered with a methylammonium lead trihalide perovskite absorber layer which shows good absorber characteristics at visible wavelengths.Both the standalone thermistor and the complete bolometer devices show polymer PTC thermistor-like behavior over a temperature range of 17 to 36℃,with a change in resistance up-to six orders of magnitude over this temperature range.The addition of the perovskite absorber to the thermistor structure provides the illumination-dependent behavior proper to bolometers.

Spatial beam reshaping and large-band nonlinear conversion in rectangular-core phosphate glass fibers

Here we present the ability of Nd^(3+)-doped zinc-phosphate glasses to be shaped into rectangular core fibers.At first,the physico-chemical properties of the developed P_(2)O_(5)-based materials are investigated for different concentrations of neo-dymium oxide and core and cladding glass compositions are selected for further fiber development.A modified stack-and-draw technique is used to produce multimode large rectangular-core optical fibers.Self-guided nonlinear effects acting as spatial beam reshaping processes occurring in these newly-developed photonic structures lead to the generation of spectral broadenings in the visible and near-infrared spectral domains.

Mechanical strength of soda-lime glass sandblasted by gravitation

Damage to a glass surface by sandblasting has a remarkable effect on its mechanical properties and strength.In this study,we analyze the superficial deterioration of soda-lime glass and its influence on the mechanical strength.Sandblasting by gravitation from a fixed height causes damages by the free fall of different quantities of sand,which we performed for a selected grain size and at different angles of inclination.To characterize the surface state,we used different roughness measures(the arithmetic mean value of the roughness Ra,the root mean square roughness Rq,and the maximum roughness Rmax)and measured the optical transmission(transmittance)at different points on the specimen surface using a profilometer.To determine the mechanical strength,we proceeded by two methods:first,by a shock ball(falling ball),and then by biaxial bending using circular supports.The effects of the surface damage on the optical transmission and the mechanical strength of the glass are graphically presented and discussed in this paper.

Third-order nonlinear optical susceptibility of crystalline oxide yttria-stabilized zirconia

Nonlinear all-optical technology is an ultimate route for the next-generation ultrafast signal processing of optical communication systems.New nonlinear functionalities need to be implemented in photonics,and complex oxides are considered as promising candidates due to their wide panel of attributes.In this context,yttria-stabilized zirconia(YSZ)stands out,thanks to its ability to be epitaxially grown on silicon,adapting the lattice for the crystalline oxide family of materials.We report,for the first time to the best of our knowledge,a detailed theoretical and experimental study about the third-order nonlinear susceptibility in crystalline YSZ.Via self-phase modulation-induced broadening and considering the in-plane orientation of YSZ,we experimentally obtained an effective Kerr coefficient of n2YSZ=4.0±2×10^-19 m^2·W^-1 in an 8%(mole fraction)YSZ waveguide.In agreement with the theoretically predicted n2YSZ=1.3×10^-19 m^2·W^-1,the third-order nonlinear coefficient of YSZ is comparable with the one of silicon nitride,which is already being used in nonlinear optics.These promising results are a new step toward the implementation of functional oxides for nonlinear optical applications.

贝尔定理:一位实验学家的朴素观点

译者的话双光子纠缠实验,是自20世纪70年代开展以来,验证贝尔不等式、证明量子力学非局域性的主要实验。法国科学家阿兰·阿斯佩(Alain Aspect)在20世纪80年代做了第一个数据令人信服的实验,获得了2022年诺贝尔物理学奖。