Multiplication and division of the orbital angular momentum of light with diffractive transformation optics

We present a method to efficiently multiply or divide the orbital angular momentum (OAM) of light beams using a sequence of two optical elements. The key-element is represented by an optical transformation mapping the azimuthal phase gradient of the input OAM beam onto a circular sector. By combining multiple circular-sector transformations into a single optical element, it is possible to perform the multiplication of the value of the input OAM state by splitting and mapping the phase onto complementary circular sectors. Conversely, by combining multiple inverse transformations, the division of the initial OAM value is achievable, by mapping distinct complementary circular sectors of the input beam into an equal number of circular phase gradients. The optical elements have been fabricated in the form of phase-only diffractive optics with high-resolution electron-beam lithography. Optical tests confirm the capability of the multiplier optics to perform integer multiplication of the input OAM, while the designed dividers are demonstrated to correctly split up the input beam into a complementary set of OAM beams. These elements can find applications for the multiplicative generation of higher-order OAM modes, optical information processing based on OAM-beams transmission, and optical routing/switching in telecom.Comment: 28 pages, 10 figure

Total angular momentum sorting in the telecom infrared with silicon Pancharatnam-Berry transformation optics

Parallel sorting of orbital angular momentum (OAM) and polarization has recently acquired paramount importance and interest in a wide range of fields ranging from telecommunications to high-dimensional quantum cryptography. Due to their inherently polarization-sensitive optical response, optical elements acting on the geometric phase prove to be useful for processing structured light beams with orthogonal polarization states by means of a single optical platform. In this work, we present the design, fabrication and test of a Pancharatnam-Berry optical element in silicon implementing a log-pol optical transformation at 1310 nm for the realization of an OAM sorter based on the conformal mapping between angular and linear momentum states. The metasurface is realized in the form of continuously-variant subwavelength gratings, providing high-resolution in the definition of the phase pattern. A hybrid device is fabricated assembling the metasurface for the geometric phase control with multi-level diffractive optics for the polarization-independent manipulation of the dynamic phase. The optical characterization confirms the capability to sort orbital angular momentum and circular polarization at the same time.Comment: 15 pages, 10 figure

Non-paraxial design and fabrication of a compact OAM sorter in the telecom infrared

A novel optical device is designed and fabricated in order to overcome the limits of the traditional sorter based on log-pol optical transformation for the demultiplexing of optical beams carrying orbital angular momentum (OAM). The proposed configuration simplifies the alignment procedure and significantly improves the compactness and miniaturization level of the optical architecture. Since the device requires to operate beyond the paraxial approximation, a rigorous formulation of transformation optics in the non-paraxial regime has been developed and applied. The sample has been fabricated as 256-level phase-only diffractive optics with high-resolution electron-beam lithography, and tested for the demultiplexing of OAM beams at the telecom wavelength of 1310 nm. The designed sorter can find promising applications in next-generation optical platforms for mode-division multiplexing based on OAM modes both for free-space and multi-mode fiber transmission.Comment: 12 pages, 8 figure

Towards Distributed Mobile Computing

In the latest years, we observed an exponential growth of the market of the mobile devices. In this scenario, it assumes a particular relevance the rate at which mobile devices are replaced. According to the International Telecommunicaton Union in fact, smart-phone owners replace their device every 20 months, on average. The side effect of this trend is to deal with the disposal of an increasing amount of electronic devices which, in many cases, arestill working. We believe that it is feasible to recover such an unexploited computational power. Through a change of paradigm in fact, it is possible to achieve a two-fold objective: 1) extend the mobile devices lifetime, 2) enable a new opportunity to speed up mobile applications. In this paper we aim at providing a survey of state-of-art solutions aim at going in the direction of a Distributed Mobile Computing paradigm. We put in evidence the challenges to be addressed in order to implement this paradigm and we propose some possible future improvements

Test of mode-division multiplexing and demultiplexing in free-space with diffractive transformation optics

In recent years, mode-division multiplexing (MDM) has been proposed as a promising solution in order to increase the information capacity of optical networks both in free-space and in optical fiber transmission. Here we present the design, fabrication and test of diffractive optical elements for mode-division multiplexing based on optical transformations in the visible range. Diffractive optics have been fabricated by means of 3D high-resolution electron beam lithography on polymethylmethacrylate resist layer spun over a glass substrate. The same optical sequence was exploited both for input-mode multiplexing and for mode sorting after free-space propagation. Their high miniaturization level and efficiency make these optical devices ideal for integration into next-generation platforms for mode-division (de)multiplexing in telecom applications.Comment: 4 pages, 1 extended references page, 6 figures. arXiv admin note: substantial text overlap with arXiv:1610.0744

Design, fabrication and characterization of Computer Generated Holograms for anti-counterfeiting applications using OAM beams as light decoders

In this paper, we present the design, fabrication and optical characterization of computer-generated holograms (CGH) encoding information for light beams carrying orbital angular momentum (OAM). Through the use of a numerical code, based on an iterative Fourier transform algorithm, a phase-only diffractive optical element (PH-DOE) specifically designed for OAM illumination has been computed, fabricated and tested. In order to shape the incident beam into a helicoidal phase profile and generate light carrying phase singularities, a method based on transmission through high-order spiral phase plates (SPPs) has been used. The phase pattern of the designed holographic DOEs has been fabricated using high-resolution Electron-Beam Lithography (EBL) over glass substrates coated with a positive photoresist layer (polymethylmethacrylate). To the best of our knowledge, the present study is the first attempt, in a comprehensive work, to design, fabricate and characterize computer-generated holograms encoding information for structured light carrying OAM and phase singularities. These optical devices appear promising as high-security optical elements for anti-counterfeiting applications.Comment: 24 pages, 9 figures. Supplementary info: 8 pages, 3 figure

Gingival overgrowth caused by Olmesartan Medoxomil: Observational study

Objective: Olmesartan Medoxomil is a type 1 receptor antagonist an antagonist of type 1 receptor (AT1) of angiotensin II (A-II) that inhibits numerous actions of A-II in the renin-angiotensin-aldosterone system (RAAS). A-II is a significant and multifunctional peptide involved in the pathophysiology of blood hypertension and for this reason it represents the main target in several classes of drugs used to treat and control arterial hypertension, such as angiotensin converting enzyme inhibitors (ACE-i), angiotensin receptor blockers (ARB) and renin direct inhibitors. The aim of the study is to evaluate whether the two drugs that have as an active principle Olmesartan Medoxomil, with and without the diuretic hydrochlorothiazide, are able to determine gingival overgrowth. Study Design: 108 subjects were examined and divided into three groups: G1, subjects treated with Olmesartan Medoxomil and hydrochlorothiazide (n=60); G2, subjects received only Olmesartan Medoxomil (n=24); G3, control group without pharmacological therapies (n=24). The plaque index (IP) and the gingival overgrowth index (OI) were recorded, considering the vertical and horizontal components. Results: Vertical overgrowth averaged between 0.17 \ub1 0.15 (G3) and 0.34 \ub1 0.26 (G2) showing statistically significant differences (p <0.05) compared to the other groups. Horizontal overgrowth ranged from 0.18 \ub1 0.26 (G3) to 0.49 \ub1 0.35 (G2) showing statistically significant differences (p <0.05). Conclusions: antihypertensive agents as Olmesartan Medoxomil may result in mild gingival overgrowth in the upper and lower frontal dental elements not related to other etiological factors

A Hierarchical Approach for Resource Management in Heterogeneous Systems

Heterogeneous architectures are emerging as a dominant trend for HPC, mainly thanks to their high performance-per-watt ratio. Dealing with heterogeneity and task-based applications requires to consider different aspects at both infrastructures level and single node in order to meet power, thermal and performance requirements. Thus, in order to provide an effective and fine-grained management of the available resources, as well as balancing the load by dispatching applications among the different computing nodes, we proposed a hierarchical approach in which different resource managers, running in the nodes, collaborate to reach a multi-objectives optimization