Resonant dielectric multilayer with controlled absorption for enhanced total internal reflection fluorescence microscopy.

Total internal reflection fluorescence microscopy (TIRF-M) is widely used in biological imaging. Evanescent waves, generated at the glass-sample interface, theoretically strongly improve the axial resolution down to a hundred of nanometers. However, objective based TIRF-M suffers from different limitations such as interference fringes and uneven illumination, mixing both propagating and evanescent waves, which degrade the image quality. In principle, uneven illumination could be avoided by increasing the excitation angle, but this results in a drastic loss of excitation power. We designed dedicated 1D photonic crystals in order to circumvent this power loss by directly acting on the intensity of the evanescent field at controlled incident angles. In this framework, we used dedicated resonant multi-dielectric stacks, supporting Bloch surface waves and resulting in large field enhancement when illuminated under the conditions of total internal reflection. Here, we present a numerical optimization of such resonant stacks by adapting the resulting resonance to the angular illumination conditions in TIRF-M and to the fluorescence collection constraints. We thus propose a dedicated resonant structure with a control of the absorption during thin film deposition. A first experimental demonstration illustrates the concept with a 3-fold fluorescence enhancement in agreement with the numerical predictions.

Semi-automated method for the determination of the all-optical monitoring strategy of complex thin-film filters.

One of the critical steps in the fabrication of complex optical interference filters is the precise control of the thickness of the layers during the fabrication process. However, the definition of the optimal optical monitoring strategy remains a challenge as it relies on user experience and there is no reliable automatic determination of this strategy. Here, we propose a semi-automated method that allows the determination of the optimal strategy. It is based on the combination of trinary mappings to select spectral regions that are compatible with optical monitoring and the use of the reflected phase error at a single wavelength versus optical monitoring wavelength. We show how this procedure can be used for the determination of either a single optical monitoring wavelength or a multi-wavelength procedure of a complex filter and confirm these theoretical results with an experimental demonstration.

Sensitivity of resonance properties of all-dielectric multilayers driven by statistical fluctuations.

In photonics and emerging fields of quantum and topological materials, increasing demands are placed upon the state and control of electromagnetic fields. Dielectric multilayer materials may be designed and optimized to possess extremely sharp spectral and angular photonic resonances allowing for the creation of fields orders of magnitude larger than the exciting field. With enhancements of 104 and higher, the extreme nature of these resonances places high constraints on the statistical properties of the physical and optical characteristics of the materials. To what extent the spectral and angular shifts occur as a result of fluctuations in the refractive indices and morphologies of the involved low-loss subdomains have not been considered previously. Here, we present how parameter variations such as those caused by fluctuations in deposition rate, yielding bias, random and compensated errors, may affect the resonance properties of low-loss all-dielectric stacks.

In situ optical monitoring of Fabry-Perot multilayer structures: analysis of current techniques and optimized procedures.

Single cavity Fabry-Perot filters are one of the most popular designs for the production of narrow bandpass filters. The usual deposition strategy to create such filters based on optical monitoring at the filter central wavelength is well-known and has proven its strength over decades. We review in this paper the possible optical methods to monitor such a filter during production and analyze their strengths and weaknesses. Then, we discuss a new monitoring procedure, mixing different methods, to minimize the production errors of this filter while maintaining a precise filter centering. This strategy is applied on different bandpass filter designs.

Bandwidths limitations of giant optical field enhancements in dielectric multi-layers.

Dielectric multilayers, when properly optimized, have been shown to sustain giant optical field enhancement directly linked to the imaginary index of the materials. Such giant optical field is of great interests to increase tremendously the sensitivity of optoelectronic systems. Unfortunately, this ultra-sensitive system is also highly depending on the illumination conditions. We discuss here the effect of the angular divergence and the spectral bandwidth of the incident laser beam on the absorption and field enhancement. In this study, we clearly show that giant optical field enhancements, up to several decades, may be achievable when the incident conditions are down few µrad and pm in term of angular and spectral bandwidths respectively.

2 × 1D crossed strongly modulated gratings for polarization independent tunable narrowband transmission filters.

We design a narrowband polarization independent transmission guided mode resonance filter whose center wavelength is tunable with respect to the angle of incidence. The device is composed of two identical structures assembled back to back. Each half structure is a dielectric multilayer stack in which a grating is engraved. This so-called 2×1D crossed gratings component has already been demonstrated for reflection filtering [Opt. Lett.36, 1662 (2011)OPLEDP0146-959210.1364/OL.36.001662; Opt. Lett.39, 6038 (2014)OPLEDP0146-959210.1364/OL.39.006038]. The functioning in transmission requires the use of a high index material for the grating bumps. For the design, we resort to a clustering global optimization algorithm, used for the first time to our knowledge for grating structures. We demonstrated two filters with a quality factor of about 4000, tunable over more than 15 nm when the angle of incidence varies over a range of 4°, and with a transmittivity at resonance greater than 95% whatever the incident polarization.

HLA DQB1*0301 allele is involved in the susceptibility to erythema multiforme.

Erythema multiforme (EM) is an acute, episodic inflammatory disorder of the skin and mucous membranes of various etiology that could be related to immunologic hypersensitivity response. EM has been previously reported to be associated with serologically defined HLA-DRw53 and DQw3 antigens. In this report, we reevaluate the role of HLA class II alleles in EM manifestations. With use of the polymerase chain reaction, followed by sequence-specific oligonucleotide hybridization, 35 unrelated Caucasian EM patients and 80 randomly selected healthy subjects were studied, and the DRB3, DRB4, DQA1, and DQB1 alleles were analyzed. The comparison of frequencies of these alleles indicates that (i) susceptibility to EM disease is more associated with the HLA-DQ than the HLA-DR subregions and (ii) that the DQB1*0301 is the most frequent allele among EM patients. Sixty-six percent of the patients had the DQB1*0301 allele compared to 31% of the controls (RR = 4.1; p less than 0.001). An even stronger DQB1*0301 association was found in the patient group with herpes-associated EM (76%; RR = 6.5; p less than 0.001). Our data demonstrate a clear association between an HLA-DQB1 allele and susceptibility to EM.

The anticentromere antibody: disease specificity and clinical significance.

Serum samples from 539 subjects were screened for the presence of the anticentromere antibody on a human laryngeal carcinoma (HEp-2) cell line (Antibodies, Inc.). The antibody was present in 61 patients (11%), most of whom had features of limited scleroderma or the CREST syndrome (calcinosis cutis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangiectasia), either independently or in association with primary biliary cirrhosis. The antibody was rarely found in patients with rapidly advancing or diffuse scleroderma. The anticentromere antibody is therefore a useful prognostic indicator in patients with early scleroderma, as it may help to predict what pattern of scleroderma will evolve. Screening for this antibody should be conducted in all patients with Raynaud's phenomenon, primary biliary cirrhosis, and scleroderma. Other previous studies have indicated a similar disease specificity and prognostic importance of this antibody.

Dipole radiation into grating structures

We present a detailed electromagnetic analysis for the radiation of an electric source located inside grating structures. Our analysis is based on the differential method and uses the scattering-matrix algorithm. We show that gratings that exhibit periodic modulations along two spatial directions (crossed gratings) enable one to couple out the totality of the light emitted by the source into the guided modes of the structure. This property is investigated through the computation of the far-field radiation patterns for crossed gratings with various etching depths. One key result is the possibility to confine the emitted light in a direction about the sample normal, a property that is of interest in the context of spontaneous emission control by microcavity structures.

[Hemangiomas and superficial vascular malformations: classification]. / Hémangiomes et malformations vasculaires superficielles: classification.

Superficial vascular malformations of the face, trunk and limbs are better known today, and they can be divided up into simple and complex vascular malformations. Simple vascular malformations may form five major categories: immature hemangiomas of infants, port-wine stains, capillarovenous angiodysplasias, and arteriovenous fistulae and malformations. Complex angiodysplasias are systematized (Sturge-Weber and Bonnet-Dechaume-Blanc syndromes, Cobb's metameric angiomatosis, Klippel-Trenaunay and Parkes Weber's syndromes) or disseminated (Weber-Osler-Rendu disease and blue rubber-bleb nevus syndrome). Various modalities of treatment may be contemplated, according to the type of malformations, and an interdisciplinary consultation is essential to decide whether a watch-and-wait policy, a physical method (laser), embolization, fibrosing injections, vascular, maxillofacial or plastic surgery, or a successive combination of various techniques should be resorted to.

[Exploration strategy for superficial vascular malformations]. / Stratégie d'exploration des malformations vasculaires superficielles.

Transillumination of cystic lymphangiomas, MRI of venous vascular malformations, pulsed Doppler and arteriography of arteriovenous malformations, echo-Doppler and radiomeasurement of malformations in the lower limbs are key examinations in the exploration strategy for superficial vascular malformations.

[Venous vascular malformations and their treatment with Ethibloc]. / Les malformations vasculaires veineuses et leur traitement par Ethibloc.

The use of Ethibloc must be contemplated as a first-intention treatment for venous malformations of the face. This sclerosing agent has transformed the functional, esthetic and psychological prognosis for these vascular malformations.

[Cystic lymphatic malformations and their treatment]. / Les malformations lymphatiques kystiques et leur traitement.

Lymphangiomas are remarkably well amenable to treatment with direct aspiration then embolization with a sclerosing agent derived from maize: Ethibloc.

A high accuracy femto-/picosecond laser damage test facility dedicated to the study of optical thin films.

A laser damage test facility delivering pulses from 100 fs to 3 ps and designed to operate at 1030 nm is presented. The different details of its implementation and performances are given. The originality of this system relies the online damage detection system based on Nomarski microscopy and the use of a non-conventional energy detection method based on the utilization of a cooled CCD that offers the possibility to obtain the laser induced damage threshold (LIDT) with high accuracy. Applications of this instrument to study thin films under laser irradiation are presented. Particularly the deterministic behavior of the sub-picosecond damage is investigated in the case of fused silica and oxide films. It is demonstrated that the transition of 0-1 damage probability is very sharp and the LIDT is perfectly deterministic at few hundreds of femtoseconds. The damage process in dielectric materials being the results of electronic processes, specific information such as the material bandgap is needed for the interpretation of results and applications of scaling laws. A review of the different approaches for the estimation of the absorption gap of optical dielectric coatings is conducted and the results given by the different methods are compared and discussed. The LIDT and gap of several oxide materials are then measured with the presented instrument: Al(2)O(3), Nb(2)O(5), HfO(2), SiO(2), Ta(2)O(5), and ZrO(2). The obtained relation between the LIDT and gap at 1030 nm confirms the linear evolution of the threshold with the bandgap that exists at 800 nm, and our work expands the number of tested materials.

Increasing the angular tolerance of resonant grating filters with doubly periodic structures.

One can increase the angular tolerance of resonant grating filters without modifying the spectral bandwidth by adding a second grating component parallel to the first one. The angular tolerance and the filter linewidth can be controlled by the designer in an independent way. Numerical results show that this property permits the use of waveguide-grating filters with standard collimated beams.