Étude et réalisation de cristaux photoniques à base de polymère: Applications à l’optique non-linéaire et à l’optique quantique

We have investigated the optical properties of polymer-based photonic crystals and photonic quasicrystals. We have demonstrated a great interest of using quasi-periodic structures to obtain an isotropic photonic bandgap, with material possessing low refractive index. These photonic structures are very promising for different applications, for example, coupling to active particles to enhance the fluorescence or nonlinear signal.We have proposed and implemented new technologies for the fabrication of polymer-based sub-micrometer photonic structures. Two original techniques are successfully demonstrated : i) the multiple-exposure two-beam interference technique, and ii) the direct laser writing based on ultra-low one-photon absorption. Each technique has its own advantages, but they are all simple and low-cost, and allows to realize arbitrary structures in 1D, 2D, and 3D.Besides, we have investigated the linear/nonlinear optical properties of various polymers. In particular, two kinds of polymers, photochromic and azobenzene, with different forms (thin films or micro-structures) are studied in detail, showing different promising applications. The optical and magnetic properties of NV color centers in diamond (bulk or nanocrystal) are also investigated and demonstrated to be very useful. Indeed, it allows to realize a perfectly stable single photon source at room temperature. The optical manipulation of a single electron spin associated to an individual NV center is also demonstrated, showing promising applications such as ultrasensitive magnetic or electric sensor.Finally, we have demonstrated theoretically and experimentally a few techniques to overcome the diffraction limit barrier in an optical microscope, which are useful for super-resolution imaging and fabrication.Les propriétés des cristaux photoniques et quasi-cristaux photoniques sont étudiées théorique- ment et expérimentalement. Nous avons démontré l’intérêt des structures quasi-périodiques en vue de l’obtention d’une bande photonique interdite isotrope avec un matériau de faible indice de réfraction. Ces structures photoniques sont très prometteuses pour améliorer les propriétés optiques des particules actives via un couplage photonique.A cet effet, nous avons mis en œuvre de nouvelles technologies de fabrication pour réaliser des structures photoniques sub-micrométriques 1D, 2D, et 3D à base de matériaux polymères. Les deux techniques originales sont i) l’interférences de deux faisceaux laser avec une exposition multiple et ii) la gravure directe par absorption ultra-faible à un photon. Chaque technique présente ses avantages propres, mais elles sont toutes simples et à faible coût.Nous avons ensuite réalisé des études en optique linéaire et non-linéaire de matériaux poly- mères sous leurs différentes formes (couches minces ou structures), et mis en évidence un vaste choix d’applications intéressantes. Les propriétés optiques et magnétiques des centres colorés NV dans le diamant (massif ou nanocristal) sont également étudiées en détail. Ces centres peuvent déboucher sur plusieurs applications telles que la source de photons uniques à température ambiante, le capteur ultrasensible de champs magnétiques et électriques, ou encore l’informa- tion quantique. Les interactions entre ces matériaux actifs et les structures photoniques sont également étudiées.Finalement, nous avons mis au point théoriquement et expérimentalement quelques tech- niques pour surmonter le problème de la limite de diffraction dans un microscope optique, afin de réaliser une imagerie optique super-résolue

One-Photon Absorption-Based Direct Laser Writing of Three- Dimensional Photonic Crystals

A simple and low-cost technique called low one-photon absorption (LOPA) direct laser writing (DLW) is demonstrated as an efficient method for structuration of multidimensional submicrostructures. Starting from the diffraction theory of the electromagnetic field distribution of a tightly focused beam, the crucial conditions for LOPA-based DLW are theoretically investigated, and then experimentally demonstrated using a simple optical confocal microscope. Various 1D, 2D, and 3D submicrostructures were successfully fabricated in different materials, such as commercial SU8 photoresist and magnetic nanocomposite. The advantages and drawbacks of this LOPA-based DLW technique were also studied and compared with the conventional two-photon absorption based DLW. Several methods were proposed to overcome the existing problem of the DLW, such as the dose accumulation and shrinkage effect, resulting in uniform structures with a small lattice constant. The LOPA-based DLW technique should be useful for the fabrication of functionalized structures, such as magneto-photonic and plasmon photonic crystals and devices, which could be interesting for numerous applications

Arbitrary Form Plasmonic Structures: Optical Realization, Numerical Analysis and Demonstration Applications

Surface plasmon resonance has attracted more and more attention thanks to its wide range of applications in numerous fields (physics, chemistry, biology, etc.). In this chapter, we present different aspects, from theoretical calculation and experimental fabrication to applications demonstration, related to arbitrary shape plasmonic nanostructures. First, numerical calculations based on finite-difference time-domain method were realized to investigate the plasmonic properties of gold nanostructures having various size and shapes. Then the direct laser writing method was demonstrated as an excellent tool for fabrication on demand of arbitrary nanostructures. Plasmonic structures were obtained indirectly by a standard lift-off method from a polymeric template and directly by tightly focusing a continuous-wave laser beam onto a metallic thin film. Finally, demonstration of various applications of fabricated plasmonic structures, namely plasmonic-based data storage, color nanoprinter, tunable filters, and plasmonic-magneto-optics sensors will be shown

Preliminary data on the aquatic invertebrate fauna of the Ma River, Thanh Hoa province: Research article

A field survey for the invertebrate fauna conducted in the Ma River, Thanh Hoa province in 2013. The research applied multivariable analysis performed by the Primer v.6 software, such as CLUSTER, one-way ANOSIM, BEST and DIVERSE. The results showed a list of 138 aquatic invertebrate species. Of these, most were freshwater wide-distributing species coupled with others characterized for brackish and marine waters. The biodiversity status was quite high compared to several other rivers in the North of Vietnam. The list contained many economic-valued species and 2 of these were listed in the Red Data Book of Vietnam. The aquatic invertebrates showed a significant relation to the two different combinations of physiochemical factors for zooplanktons and zoobenthos, respectively. The values of the species number, abundance and Shannon-Weiner index for both of zooplanktons and zoobenthos showed a curved trend from the upper river segments to lower river segments. These figures for zooplanktons peaked in the middle river segments, whereas the numbers for zoobenthos achieved the highest numbers in the estuaries. The species composition of the estuaries differentiated significantly from that of other freshwater habitats.Năm 2013 đã tiến hành một đợt điều tra khu hệ động vật không xương sống sông Mã, tỉnh Thanh Hóa. Nghiên cứu sử các phân tích đa biến thông qua phần mền Primer v.6, bao gồm: CLUSTER, one-way ANOSIM, BEST và DIVERSE. Kết quả phân tích thu được 138 loài với thành phần loài chủ yếu là những loài nước ngọt thường gặp và phân bố rộng, ngoài ra còn có các loài đặc trưng cho nước lợ và mặn. Trong số các loài thu được, nhiều loài có giá trị kinh tế và 2 loài có tên trong Sách Đỏ Việt Nam. Khu hệ động vật không xương sống sông Mã có quan hệ chặt với hai nhóm chỉ số thủy lý hóa học khác nhau, tương ứng cho động vật nổi và động vật đáy. Giá trị các chỉ số sinh học gồm số lượng loài, mật độ và Shannon-Weiner hồi quy theo đường cong phi tuyến từ thượng lưu tới hạ lưu; đạt giá trị cao nhất tại cửa sông đối với động vật đáy và vùng trung lưu với động vật nổi. Thành phần loài cửa sông khác biệt rõ rệt với thành phần loài các sinh cảnh nước ngọt khác

The JCMT BISTRO Survey: Revealing the diverse magnetic field morphologies in Taurus dense cores with sensitive sub-millimeter polarimetry

© 2021. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/We have obtained sensitive dust continuum polarization observations at 850 $\mu$m in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope (JCMT), as part of the BISTRO (B-fields in STar-forming Region Observations) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution ($\sim$2000 au or $\sim$0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis-Chandrasekhar-Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38$\pm$14 $\mu$G, 44$\pm$16 $\mu$G, and 12$\pm$5 $\mu$G, respectively. These cores show distinct mean B-field orientations. B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field, and not well-correlated with other axes. In contrast, Miz-8b exhibits disordered B-field which show no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux.Peer reviewe