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While the quantum metrological advantages of performing non‐Gaussian operations on two‐mode squeezed vacuum (TMSV) states have been extensively explored, similar studies in the context of two‐mode squeezed thermal (TMST) states are severely lacking. This paper explores the potential advantages of performing non‐Gaussian operations on TMST state for phase estimation using parity detection‐based Mach–Zehnder interferometry and compares it with the TMSV case. To this end, a realistic photon subtraction, addition, and catalysis model is considered. A unified Wigner function of the photon subtracted, photon added, and photon catalyzed TMST state is derived, which is used to obtain the expression for the phase sensitivity. The results show that performing non‐Gaussian operations on TMST states can enhance the phase sensitivity for significant squeezing and transmissivity parameter ranges. Because of the probabilistic nature of these operations, it is of utmost importance to consider their success probability. When the success probability is considered, the photon catalysis operation performed using a high transmissivity beam splitter is the optimal non‐Gaussian operation. This contrasts with the TMSV case, where photon addition is observed as the most optimal. Further, the derived Wigner function of the non‐Gaussian TMST states will be useful for state characterization and various quantum protocols. [ABSTRACT FROM AUTHOR]

Design of the optical devices is an important matter of discussion in the present scenario where optical devices have become ultra‐compact due to miniaturization, ultra‐speed with the integration of optoelectronic devices. In this paper a 1 × 3 2D photonic crystal based on optical beam‐splitter has been designed on OptiFDTD for TE polarized light. The wafer is of the dimensions of 21 µm × 15 µm in length and width, respectively. The design works at the wavelength of 1.55 µm, and the mode is selected to be the Gaussian Modulated Continuous Wave (GMCW). The design is based on the 2D Hexagonal lattice, where the elliptical Si‐rods are placed in the air. This splitter prototype consists of one input and three outputs with the split ratio as 60:20:20. This refers to the first output port has 60% power of the transmitted signal, and the second and the third output ports have 20% power of the input. The structure is implemented using OptiFDTD software. It utilizes Finite Domain Time Difference (FDTD) numerical method to analyze the transmission spectra of the structure, and the Plane Wave Expansion (PWE) method is utilized to calculate the photonic bandgap of the prototype. [ABSTRACT FROM AUTHOR]

Polarization manipulation is essential in photonic integrated circuits and has numerous applications in various fields, such as optical communication, nonlinear optics, and quantum optics. Advances in nanofabrication have enabled the integration of subwavelength‐structured metamaterials on optical waveguides, providing unprecedented optical manipulation capabilities beyond classical waveguide‐based architectures. In this paper, the polarization space is demonstrated to be fully manipulated by a dielectric metamaterial composed of nanoholes and nanoslots. This approach offers competitive performances for key polarization components, including the polarizer, polarization beam splitter, and polarization‐splitter‐rotator, while maintaining ultra‐compact coupling regions of 18×1 µm2, 16×1.1 µm2, and 13×1 µm2 respectively. The devices are designed by manipulating the phase and amplitude of all possible eigenmodes supported in the waveguide, which is inherently scalable and versatile for on‐chip mode and wavefront manipulation. The unique properties of metamaterials provide powerful tools for on‐chip polarization manipulation and offer new possibilities for the development of compact and high‐performance photonic integrated circuits. [ABSTRACT FROM AUTHOR]

The emergence of new materials and fabrication techniques provides progress in the development of advanced photonic and communication devices. Transition metal dichalcogenides (e.g., molybdenum disulfide, MoS2) are novel materials possessing unique physical and chemical properties promising for optical applications. In this paper, a metasurface composed of particles made of bulk MoS2 is proposed and numerically studied considering its operation in the near‐infrared range. In the bulk configuration, MoS2 has a layered structure being a uniaxial anisotropic crystal demonstrating an optical birefringence property. It is supposed that the large‐scale and uniform MoS2 layers are synthesized in a vertical‐standing morphology, and then they are patterned into a regular 2D array of disks to form a metasurface. The natural anisotropy of MoS2 is utilized to realize the splitting of electric and magnetic dipole modes of the disks while optimizing their geometric parameters to bring the desired modes into overlap. At the corresponding resonant frequencies, the metasurface behaves as either an electric or a magnetic mirror, depending on the polarization of incident light. Based on the extraordinary reflection characteristics of the proposed metasurface, it can be considered an alternative to traditional mirrors and optical splitters when designing compact and highly efficient metadevices, which provide polarization and phase manipulation of electromagnetic waves on a subwavelength scale. [ABSTRACT FROM AUTHOR]

The development of high‐efficiency compact non‐mechanical beam tuning devices has attracted a lot of attention for light detection and ranging, augmented reality display, and chip‐to‐chip communication. Owing to the fast wavefront manipulation in an ultra‐thin dimension, metasurfaces have been regarded as potential substitutes for traditional tunable optical components toward further miniaturization and low power consumption. However, most beam tuning metasurfaces currently are polarization‐sensitive and designed to work in reflection mode, which limit their applications in integrated optical systems for full‐range steering. In this paper, a transmission mode polarization‐insensitive beam switching metasurface based on nonvolatile phase‐change material Ge2Sb2Te5 is proposed and experimentally demonstrated at the telecommunication wavelength. The high transmission efficiency with a large switching angle of up to 75° is achievable for potentially full‐range beam steering applications. As a proof of concept, the transmitted beam with a switching angle of 15° and directivity of 82.4% is demonstrated. In addition, by controlling the phase transition in the intermediate states, the metasurface can be used as a tunable beam splitter to control the ratio of the beam power between two predesigned transmission angles. The demonstrated phase‐change metasurfaces pave the way for achieving high‐efficiency dynamic beam steering for various important applications. [ABSTRACT FROM AUTHOR]

The European X‐ray Free Electron Laser (EuXFEL) offers intense, coherent femtosecond pulses, resulting in characteristic peak brilliance values a billion times higher than that of conventional synchrotron facilities. Such pulses result in extreme peak radiation levels of the order of terawatts cm−2 for any optical component in the beam and can exceed the ablation threshold of many materials. Diamond is considered the optimal material for such applications due to its high thermal conductivity (2052 W mK−1 at 300 K) and low absorption for hard X‐rays. Grating structures were fabricated on free‐standing CVD diamond of 10 µm thickness with 500 µm silicon substrate support. The grating structures were produced by electron‐beam lithography at the Laboratory for Micro‐ and Nanotechnology, Paul Scherrer Institut, Switzerland. The grating lines were etched to a depth of 1.2 µm, resulting in an aspect ratio of 16. The characterization measurements with X‐rays were performed on transmissive diamond gratings of 150 nm pitch at the P10 beamline of PETRA III, DESY. In this paper, the gratings are briefly described, and a measured diffraction efficiency of 0.75% at 6 keV in the first‐order diffraction is shown; the variation of the diffraction efficiency across the grating surface is presented. [ABSTRACT FROM AUTHOR]

The implementation of countermeasures to avoid licence abuse is now obligatory, especially with the burgeoning of the Internet. The protocol proposed here is implemented within the session initiation protocol (SIP); this has been selected as the official end‐to‐end signalling protocol for establishing multimedia sessions in the Universal Mobile Telecommunication Systems network. This paper introduces blind signatures, enforced with user‐specific and unique data, modelled from CCD sensors to trace users of these online services, thus avoiding licence sharing that gives access to them. Blind signatures are useful in providing anonymity and establishing a way to tag users. The proposed protocol takes advantage of elliptic curve‐based cryptosystems – smaller key sizes and lower computational resources, an interesting issue for session establishment in S‐Universal Mobile Telecommunication Systems (satellite‐linked networks), where fast and light authentication protocols are a requirement ideal. SIP is a powerful signalling protocol for transmitting media over Internet protocol. Authentication is a vital security requirement for SIP. Hitherto, many authentication schemes have been proposed to enhance SIP security; indeed, the problem of impersonation is one of the topics most discussed. Consequently, a novel authentication and key agreement scheme is proposed for SIP using an elliptic curve cryptosystem. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Polarization plays a critical role in optical systems that range from optical communications to imaging, lithography, metrology, and data storage. Thus, in systems that need to generate a certain polarization state, a light source (e.g., laser) is combined with polarization control elements such as polarizers, polarizing beam splitters, and waveplates. Similarly, in systems requiring polarization state detection, such elements are combined with photodetectors. There is currently a trend toward miniaturized optical systems. This motivates the question of how to achieve what may be argued as an ultimate level of miniaturization: a single chip that can both generate light with a prescribed polarization state and detect the polarization state of light impinging upon it. This paper demonstrates this via vertical cavity surface emitting lasers (VCSELs) with on‐facet metasurfaces. Two classes of devices are demonstrated. The first class uses high‐index dielectric metasurfaces (amorphous silicon nanofins), whereas the second class uses plasmonic metasurfaces (aluminum bilayer gratings). Each can operate as a laser (to generate) and as a photodetector (to detect) circularly or linearly polarized light. [ABSTRACT FROM AUTHOR]

The polarization beam splitter (PBS) is a pivotal element in the polarization management of free-space optical instruments and systems. Photonic integrated circuits for sensing, imaging, communications, and quantum-information processing also have needs for monolithically integrated PBSs with an ultra-broad optical bandwidth. In this paper, a novel silicon nanophotonic PBS inspired by the crystalline Glan-Thompson prism but implemented with silicon subwavelength-grating (SWG) metamaterials is presented. Due to the tailored artificial anisotropy of SWGs, the meta-prism functions like a thin-film reflector or a waveguide crossing for different polarizations. Thus, the incident light can be steered with strong polarization selectivity and negligible wavelength dependence. Unlike conventional PBS designs, the routing of polarized light is enabled by the wavelengthindependent total internal reflection in anisotropy-engineered effective media, thereby breaking the bandwidth limit. The device footprint is as small as ≈15 x 7 υm². Low insertion losses of 0.6-1.7 dB and high extinction ratios of 20-30 dB are experimentally achieved spanning a record broad bandwidth of over 415 nm, ranging from 1.26 to 1.675 μm wavelength. These results represent, to the best of their knowledge, the most broadband integrated PBS ever demonstrated to date. [ABSTRACT FROM AUTHOR]

This paper reports on the fabrication and characterization of X-ray waveguide beamsplitters. The waveguide channels were manufactured by electron-beam lithography, reactive ion etching and wafer bonding techniques, with an empty (air) channel forming the guiding layer and silicon the cladding material. A focused synchrotron beam is efficiently coupled into the input channel. The beam is guided and split into two channels with a controlled (and tunable) distance at the exit of the waveguide chip. After free-space propagation and diffraction broadening, the two beams interfere and form a double-slit interference pattern in the far-field. From the recorded far-field, the near-field was reconstructed by a phase retrieval algorithm (error reduction), which was found to be extremely reliable for the two-channel setting. By numerical propagation methods, the reconstructed field was then propagated along the optical axis, to investigate the formation of the interference pattern from the two overlapping beams. Interestingly, phase vortices were observed and analysed. [ABSTRACT FROM AUTHOR]

This paper proposes a beam splitter with one emitter and two collectors each on the left and right based on anisotropy of the group velocity. An anisotropic medium is represented by a two-dimensional square lattice tight-binding model. The transport property of the beam splitter is analyzed by means of the boundary-type solution method. At the center of the band where the anisotropy of the group velocity is strong, the incident beam is split into two and propagates along the diagonal directions of the square lattice with almost no diffraction. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(12): 67–75, 2002; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecjb.1114 [ABSTRACT FROM AUTHOR]

This paper assumes a simple model for the DRAW (direct-read/after-write) optical disk using a Te-alloy recording medium. The scattering of the light-beam by the pit or boss of arbitrary shape on the boundary of three-layered dielectrics is analyzed by the boundary-element method. The sum and the differential signal output characteristics of the two-split-type optical detector also is discussed. The results of simulation are shown Mr the effect of the adjacent pit in the square and V- shaped pregrooved models, the dependencies of the sum and the differential signals on the tracking error, and the dependencies of the sum and the differential signals on the pit depth, when the signal recording pit is provided in the two types of pregrooved models. [ABSTRACT FROM AUTHOR]

One of the most fundamental quantum random number generators is implemented with light impinging onto a beam splitter, and two single photon detectors at its output. Often, this generator is described as 'a photon which takes one or other path towards a detector'. The input state of light in conjunction with the detector response is relevant for the amount, the pattern, and the correlation of the generated clicks. Only a fraction of all generator outcomes, the min-entropy, can be used as a further resource for true randomness. This paper addresses the difference in the common description with incoming single photons and the often implemented scheme with a weak coherent light source, such as an attenuated laser. For this very fundamental and widely used configuration the amount of usable entropy is compared. If single photons from an anti-bunched light source are supplied, the amount of entropy is higher than for the case of a supplied coherent state - although the latter can be arbitrarily bright unlike the single photon source. [ABSTRACT FROM AUTHOR]

In this paper, we introduce two kind of beam splitter for applied on the autostereoscopic displays, which is diffractive optical element, and holographic optical element. From the results showing the high performance, they have high brightness and suitable three-dimensional effects that own higher diffractive efficiency and lowest crosstalk. [ABSTRACT FROM AUTHOR]

For the miniaturization of optical devices, surface plasmon polaritons (SPPs) have been widely utilized due to their outstanding confinement and field-enhancement characteristics. Analyzing a spectrum of optical signals and splitting certain regions of the spectrum range within a submicrometer-scale structure are demanded for optical integrated systems. In this paper, a novel type of dichroic surface plasmon launcher that can switch the launching direction according to incident polarization states is demonstrated. Compared to the previously reported plasmonic dichroic splitters, the proposed schemes do not use any asymmetric geometry for directional launching. Hence, the direction of guided SPPs can be interchanged according to the polarization state. Such characteristics will be helpful to design switchable plasmonic devices that can be applied to active plasmonic integrated circuits. [ABSTRACT FROM AUTHOR]

We present a high‐performing polarizing beam splitter for augmented reality applications using newly developed 3M™ Polarized Beam Splitter (PBS) film. It has very low light leaks which are largely independent of light incident side. At the same time, high efficiency is maintained with 96% transmission and 98% reflection integrated over an f/2 cone. Comparisons are made to a wire‐grid PBS. [ABSTRACT FROM AUTHOR]

In this paper, an analytical analysis is made on a periodic bandpass filter formed by a two-cavity etalon incorporated into a Sagnac loop interferometer. The general optimum conditions for a quasi-flat-top spectrum and a ripple-free group-delay response are derived. Our results show that by properly choosing the reflectance of the mirrors, the filter can be designed with a quasi-flat-top spectral response that is also free from group-delay ripples. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 17–21, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20194 [ABSTRACT FROM AUTHOR]

Polarization is a fundamental property of electromagnetic waves that plays a key role in many physical phenomena and applications. Schemes to manipulate it are revisited with the emergence of metasurfaces, which have brought multi‐functionalities straightforwardly. However, this has come at the expense of design complexity that relies strongly on field theory. Here, an ingenious strategy of modular design is proposed to construct subwavelength multifunctional polarization control devices. Chiral metasurfaces with different handedness are first proposed and regarded as modules. The versatile polarization controller can thus be obtained with the combination of different modules. These experiments demonstrate that the well‐designed polarization controller possesses reconfigurable functionality, and various broadband polarization and amplitude regulation functions with high efficiency including arbitrary linear polarization rotation, asymmetric transmission effect, neutral‐density‐like filter, polarization beam splitter, etc., can be readily realized just by changing the cascaded modules. The physical mechanisms of the versatile polarization controller and chiral metasurface modules are both guaranteed by the Fabry–Pérot‐like resonances, which are theoretically verified via the transfer matrix method. It is envisioned that the modular concept will be of great benefit to designing compact multifunctional polarization controllers. [ABSTRACT FROM AUTHOR]

Many optical systems for displaying digital information on mirrors have been proposed, but information can only be displayed in either mirrored or real space and cannot move back and forth between the two. We have therefore developed a new optical system called mirror-transcending aerial imaging (MiTAi) that freely crosses the boundary between mirrored and real spaces. MiTAi is based on an existing aerial-imaging system consisting of a retroreflector, a beam splitter, and a moving display. MiTAi is designed as a spacesaving design by changing the orientation and position of the moving display as the light source. We implemented a prototype MiTAi to evaluate the luminance of the displayed aerial images and found that the aerial image formed by the prototype is able to move freely between both mirrored and real spaces. Moreover, the luminance of the image is not significantly lower than that formed by the existing aerial-imaging system. MiTAi will enable the creation of a new user experience by integrating smart mirrors and real-space aerial images. [ABSTRACT FROM AUTHOR]

A novel dual‐core structure based on cyclic olefin copolymer (COC) photonic crystal fiber (PCF) is proposed for realizing Terahertz (THz) polarization beam splitting. The dependence of coupling length and structural parameters of the THz polarization beam splitter (TPBS) is analyzed. The confinement loss, effective material loss, and extinction ratio (ER) are examined. The numerical simulation results show, two orthogonal polarization modes are separated completely within a device length of only 45.16 mm owing to the different coupling length in x‐ and y‐polarization directions. The maximum polarization ER of 107.7 dB is obtained at 0.54 THz. The bandwidth with ER greater than 20 dB reaches 0.02 THz. The proposed compact dual‐core TPBS will find extensive applications in THz photonic systems. [ABSTRACT FROM AUTHOR]

In the under‐screen fingerprint recognition of smart cell phones, the tiny image signals are easily deteriorated by the protective membranes of screens. To solve this issue, an optical waveguide comprising two stage dual‐function gratings is proposed to supply extra lighting. The first stage is formed by two adjacent gratings possessing a cross angle of 120°, which serve as couplers and beam splitters to trap and split the incident light into two paths within the optical waveguide film, respectively. The second stage gratings, possessing a 60° included angle to the first stage, act as beam orientators and expanders by consecutively redirecting a portion of the light beams towards the sensing zone. By covering the waveguide film outside on an organic light emitting diode display screen and setting a camera and a laser under the screen, this slim construction shows high efficiency and large area under‐screen fingerprint recognition with high signal contrast. The design inspires a novel method for efficiently and flexibly controlling photons by arranging a series of gratings with the proper orientations and locations on a chip, which is highly demanded in displays and optical communication. [ABSTRACT FROM AUTHOR]

Multifunctional ultra‐thin devices which can manipulate the wavefront in a desired manner are preferably required for compact systems. In recent years, metasurfaces have been treated as an intuitive and powerful platform to expand the operational capacity of planar devices. In this work, a non‐interleaved device based on metasurfaces is proposed which utilizes transmitted co‐and‐cross polarization channels of circularly polarized (CP) light to design a spin‐switchable Wollaston‐and‐Rochon‐prism‐like CP beam splitter. In addition, this scheme facilitates the design of meta‐hologram that can decrypt two independent holographic images, one on each CP transmitted channel, under the right‐handed circularly polarized light. While, under the left‐handed circularly polarized light, the co‐polarization channel reconstructs the holographic image and no image appears on the cross‐polarization channel. The intended approach provides a promising route which will find application in information encryption/decryption, multichannel communication systems, and imaging. [ABSTRACT FROM AUTHOR]

A broadband, high efficiency polarized beam splitter (PBS) metagrating based on integrated resonant units (IRUs) to enable simultaneous polarization analysis, spectral dispersion, and spatial imaging in the near infrared (NIR) is developed. A PBS metagrating with a diameter of 60 mm is the key technology component of the high‐resolution multiple‐species atmospheric profiler in the NIR (HiMAP‐NIR), which is a spaceborne instrument concept crafted to be a core payload of NASA's new generation Earth System Observatory. HiMAP‐NIR will enable the aerosol profiling in Earth's planetary boundary layer (from surface to2 km altitude) by simultaneously measuring four spatial‐spectral‐polarimetric images from 680 to 780 nm. Through detailed optimization of hybridized resonant modes in IRUs, the PBS metagrating shows a diffraction efficiency of 70% (or better) for all four linear‐polarized incident light, and polarization contrasts between orthogonal states are 0.996 (or better) from 680 to 780 nm. It meets the stringent performance required by the HiMAP‐NIR exploiting a new paradigm for the broad applications of metasurfaces. [ABSTRACT FROM AUTHOR]

The polarization beam splitter (PBS) is an essential component in the polarization diversity circuit to overcome the strong polarization dependence of silicon nanophotonic devices. Among various PBS structures, the asymmetrical directional couplers (ADCs) are most commonly used due to the best overall performances. However, it is still challenging to realize an on‐chip silicon PBS with a small footprint, low loss, high extinction ratio, and, especially, broad bandwidth, simultaneously. The working bandwidth is limited for ADCs, since the wavelength difference will introduce deviations to both the effective indices and the coupling strength, which would distort the phase‐matching property and the optimal coupling length. In this paper, an on‐chip silicon PBS is proposed and demonstrated using "effective medium anisotropy" instead of "configuration asymmetry" to break the bandwidth bottleneck. The metamaterials with engineered anisotropy and dispersion are utilized to form a hetero‐anisotropic slab. For TM polarization, the slab performs as a multi‐mode interference coupler, while for TE polarization, the slab performs as two isolated waveguides. The fabricated PBS shows low loss <1 dB, high extinction ratio >20 dB, and a record working bandwidth >200 nm, with a footprint as small as 12.25 × 1.9 µm2. An ultra‐broadband on‐chip silicon polarization beam splitter based on hetero‐anisotropic metamaterials is proposed and demonstrated. Subwavelength grating metamaterials are utilized to engineer anisotropy and dispersion. The fabricated device shows low losses <1 dB, high extinction ratios >20 dB, and a record working bandwidth >200 nm. [ABSTRACT FROM AUTHOR]

Amplitude-division beam splitters for XUV radiation sources have been developed and extensively characterized. Mo/Si multilayer coatings were deposited on 50 nm-thick SiN membranes. By changing the multilayer structure (periodicity, number of bilayers, etc.) the intensity of the reflected and transmitted beams were optimized for selected incident radiation parameters (wavelength, incident angle). The developed optical elements were characterized by means of XUV reflectometry and transmission measurements, atomic force microscopy and optical interferometry. Special attention was paid to the spatial homogeneity of the optical response and reflected beam wavefront distortions. Here the results of the characterization are presented and improvements required for advanced applications at XUV free-electron lasers are identified. A flatness as low as 4 nm r.m.s. on 3 × 3 mm beam splitters and 22 nm r.m.s. on 10 × 10 mm beam splitters has been obtained. The high-spatial-frequency surface roughness was about 0.7-1 nm r.m.s. The middle-spatial-frequency roughness was in the range 0.2-0.8 nm r.m.s. The reflection and transmission of the beam splitters were found to be very homogeneous, with a deviation of less than 2% across the full optical element. [ABSTRACT FROM AUTHOR]

The Drude tail due to photo-excited carriers in single-walled carbon nanotubes (SWNTs) has been observed in the mid-infrared region by using combination spectroscopy of synchrotron radiation and Ti:sapphire laser. It is found that the density of photo-excited carriers increases as the sample temperature is raised from 12 to 300 K, and their lifetime is of the order of minutes at 300 K. These facts suggest that the movement of photo-excited carriers is largely affected by some extrinsic defect, thus resulting in the long-lasting Drude reflection in SWNTs. [ABSTRACT FROM AUTHOR]

The design of a polarization preserving reflected beam splitter (PPRBS) is presented. The PPRBS consists of a V-shaped absorbing substrate coated with a single thin-film layer. The PPRBS operates in the UV region. The power reflection coefficient ranges from 69 to 90% for angles of incidence ranging from 85 to 89°, respectively. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 484–487, 2001. [ABSTRACT FROM AUTHOR]

A novel intersection waveguide-type polarization splitter based on total reflection using the birefringence of the GaInAsP/Inp superlattice waveguide is proposed and analyzed in this paper. The semivectorial finite difference beam propagation method (FD-BPM) (which handles both TE and TM modes) is used in the analysis. The waveguide structure including the GaInAsP/InP superlattice is designed; and it is shown that, although with a superlattice core the refractive index for the TM mode is reduced by approximately 0.4 percent, there is no change for the TE mode. Based on this result, the optimal structural parameters such as superlattice layer number, rib height (h), intersecting angle (θ), and port separation length (Lsp) are investigated using a 1.55-μm wavelength. It is found that the TE and TM modes can be separated with an insertion loss of less than 0.4 dB for both modes and a crosstalk of less than -35 dB using an intersecting angle of 5° and a device length of approximately 0.9 mm. It is shown that compared to conventional devices, the device length in the proposed device structure can be reduced by using total reflection. The wavelength dependence of the device is also analyzed. [ABSTRACT FROM AUTHOR]

For the High‐Energy‐Density (HED) beamline at the SASE2 undulator of the European XFEL, a hard X‐ray split‐and‐delay unit (SDU) has been built enabling time‐resolved pump/probe experiments with photon energies between 5 keV and 24 keV. The optical layout of the SDU is based on geometrical wavefront splitting and multilayer Bragg mirrors. Maximum delays between Δτ = ±1 ps at 24 keV and Δτ = ±23 ps at 5 keV will be possible. Time‐dependent wavefront propagation simulations were performed by means of the Synchrotron Radiation Workshop (SRW) software in order to investigate the impact of the optical layout, including diffraction on the beam splitter and recombiner edges and the three‐dimensional topography of all eight mirrors, on the spatio‐temporal properties of the XFEL pulses. The radiation is generated from noise by the code FAST which simulates the self‐amplified spontaneous emission (SASE) process. A fast Fourier transformation evaluation of the disturbed interference pattern yields for ideal mirror surfaces a coherence time of τc = 0.23 fs and deduces one of τc = 0.21 fs for the real mirrors, thus with an error of Δτ = 0.02 fs which is smaller than the deviation resulting from shot‐to‐shot fluctuations of SASE2 pulses. The wavefronts are focused by means of compound refractive lenses in order to achieve fluences of a few hundred mJ mm−2 within a spot width of 20 µm (FWHM) diameter. Coherence effects and optics imperfections increase the peak intensity between 200 and 400% for pulse delays within the coherence time. Additionally, the influence of two off‐set mirrors in the HED beamline are discussed. Further, we show the fluence distribution for Δz = ±3 mm around the focal spot along the optical axis. The simulations show that the topographies of the mirrors of the SDU are good enough to support X‐ray pump/X‐ray probe experiments. [ABSTRACT FROM AUTHOR]

Silicon photonics has attracted tremendous interest from academia and industry, as the fabrication of the silicon family of photonic devices is mostly compatible with the microelectronics process using complementary metal‐oxide semiconductors (CMOS). Herein, three silicon‐family materials are discussed: silicon, silicon nitride, and silica. In addition, hybrid integration with a 2D material, graphene, is examined. First, the material and waveguide properties are reviewed. Second, typical fabrication processes for waveguide devices are introduced. Subsequently, a variety of passive waveguide devices, operating at different physical dimensions covering wavelength, polarization, and mode, are discussed. They correspond to fixed and tunable filters, polarization beam splitters and rotators, and mode conversion and multiplexing devices. These passive waveguide devices play important roles in a wide range of applications including telecom, interconnects, computing, sensing, quantum information processing, bio‐photonics, and energy. [ABSTRACT FROM AUTHOR]

Summary: The observation with RCM of the reflection from reaction products produced by nonisotopic in situ hybridisation and a peroxidase staining, has recently facilitated the identification of single copy genes. RCM also reveals light microscope structures in stained ultrathin (0.1 μm) epon and lowicryl sections. In such preparations no out‐of‐focus blur can be observed. Confocal optics are thus not needed to obtain high‐quality images of ultrathin sections at the highest conventional light microscope optical resolution, and with higher image‐contrast than can be obtained by classical absorption microscopy. Such RCM images provide the same type of information as confocal scanning microscope images. A sequential ultrathin section of the same microscopic specimen can be examined with electron microscopy for a simple and accurate (CLEM) procedure. For some applications RCM can replace (CLSM). Lay Description: With reflection contrast microscopy (RCM), a microscope image can be observed if micromirror‐like reflecting substances are present in the reaction product of cytochemical stains. Using an antiflex objective for RCM, the reflected incident light from the stained microscope specimen can be observed with only a small amount of unwanted stray‐light in the image background. Stray‐light is caused by reflection of incident light from the surface of the lenses in the microscope objective and in the microscope tube (using a 50% beam splitter for epi‐illumination). Several authors who compared RCM with bright‐field and fluorescence microscopy, found RCM to be a sensitive microscope method in many applications. It has been reported that RCM, using in situ hybridisation methods, can detect DNA sequences in single copy genes. In the literature is mentioned that single copy genes have an estimated mass of less than a trillionth of a gram of DNA. From stained ultrathin microscope sections with less than 0.1 μm thickness, multicoloured images with a high image contrast, optimal resolution and no out‐of‐focus blur can be observed with RCM. To achieve this, RCM uses an antiflex microscope objective, with a quarter‐wave plate mounted on the front lens in combination with a polarising filter cube inserted in the epi‐illuminator. RCM can also make use of oblique illumination, for a further increase of the image‐contrast and the resolution of the microscope image. A central stop has then to be inserted in the aperture plane of an epi‐illuminator. [ABSTRACT FROM AUTHOR]

The authors demonstrate that the bits of a Compact Disc -- Read Only Memory (CD-ROM) can be read without a photodiode (PD). A commercial CD-ROM drive was used and left unmodified except a beam splitter was removed which would route the light to a PD. This allowed for the reflected light to be incident on the laser within the laser package itself. By monitoring fluctuations in the voltage across the laser diode under constant-current injection, it was possible to read and interpret the bits from a spinning CD-ROM. [ABSTRACT FROM AUTHOR]

Garnet film is widely used as a key element of optical sensors due to its Faraday effect. The polarization plane of the transmitted, linearly polarized light can be rotated when the garnet interacts with an external magnetic field. Here, an optical spot and the polarization state of a laser beam reflected from a garnet-graphite interface as a function of the external direct current (DC) voltage are measured by a Slit Beam Profiler and a Polarization Analyzing System. The results show that the garnet-graphite stress can be generated as a function of an external DC voltage, that the linearly polarized laser beam can be split into two optical spots, and that the maximum distance is 0.68 mm, while the polarization properties of the laser beam remained unchanged. [ABSTRACT FROM AUTHOR]

Damage patterns caused by the Catastrophic Optical Damage (COD) are analyzed in GaN-based high-power diode lasers. In contrast to standard failure analysis, the devices are intentionally degraded under well-defined conditions. We find that defect growth during COD is fed by the optical mode, that is, laser energy. This process involves melting and even vaporization of quantum-well and waveguide materials. Average defect propagation velocities along the laser axis of 110 m s−1 are observed. COD results in material loss including the formation of an empty channel. This is well consistent with material loss due to ejections of hot material out of the front facet of the device. The laser structure in the immediate vicinity of the empty channel seems to be absolutely undisturbed and no transition regions or remaining material are observed. These results are compared with earlier findings from comparable experiments obtained with GaAs-based devices. [ABSTRACT FROM AUTHOR]

We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two 90° optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of 2%-Δ. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/ transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a lowcost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of 8.3 × 10-11 is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing. [ABSTRACT FROM AUTHOR]

An ultrathin Huygens metasurface is proposed to manipulate orthogonally polarized transmitted waves independently. The Huygens metasurface consists of two layers of dielectric substrates and three layers of artificial metallic structures with ultrathin electric thickness. In physics, two orthogonal electric dipoles and two orthogonal magnetic dipoles are supported by each unit cell of the metasurface, which enable the complete control of phase distributions in both vertical and horizontal directions. Based on this feature, a polarization beam splitter with large splitting angle is designed and fabricated to demonstrate the capability and flexibility of the proposed Huygens metasurface. The numerical simulations and measurement results have a good match, indicating the good performance on independent controls of orthogonally polarized transmitted waves. [ABSTRACT FROM AUTHOR]

In an interferometer-based fluorescence microscope, a beam splitter is often used to combine two emission wavefronts interferometrically. There are two perpendicular paths along which the interference fringes can propagate and normally only one is used for imaging. However, the other path also contains useful information. Here we introduced a second camera to our interferometer-based three-dimensional structured-illumination microscope (I5S) to capture the fringes along the normally unused path, which are out of phase by π relative to the fringes along the other path. Based on this complementary phase relationship and the well-defined phase interrelationships among the I5S data components, we can deduce and then computationally eliminate the path length errors within the interferometer loop using the simultaneously recorded fringes along the two imaging paths. This self-correction capability can greatly relax the requirement for eliminating the path length differences before and maintaining that status during each imaging session, which are practically challenging tasks. Experimental data is shown to support the theory. [ABSTRACT FROM AUTHOR]

Purpose: Asymmetric collimators are currently available in most of linear accelerators. They involve a lot of clinical improvements, such as the monoisocentric beam split technique that is more and more used in many external radiotherapy treatments. The tolerance established for each independent jaw positioning is 1mm. Within this tolerance, a gap or overlap of the collimators up to 2mm can occur in the half beams matching region, causing dose heterogeneities up to 40%. In order to solve this dosimetric problem, we propose an accurate jaw calibration method based on the Monte Carlo modeling of linac photon beams.Methods: Simulating different jaw misalignments, the dose distribution occurring in the matching region for each particular configuration is precisely known, so we can relate the misalignment of the jaws with the maximum heterogeneity produced. From experimental measurements using film dosimetry, and taking into account Monte Carlo results, we obtain the actual misalignment of each jaw. By direct inspection of the readings of the potentiometers that control the position of the jaws, high precision correction can be performed, adjusting the obtained misalignments.Results: In the linac studied, the dose heterogeneity in the junction performed with X jaws (those farther from the source), and 6MV photon beam was initially over 12%, although each jaw was within the tolerance in position. After jaw calibration, the heterogeneity was reduced to below 3%.Conclusions: With this method, we are able to reduce the positioning accuracy to 0.2mm. Consequently, the dose distribution in the junction of abutted fields is highly smoothed, achieving the maximum dose heterogeneity to be less than 3%. [ABSTRACT FROM AUTHOR]

The polarization angle rotation of the propagating beam was estimated in a partially ionized atmosphere under discharge conditions. The polarization plane angle rotation is caused by the magneto-optical effect (Faraday effect). The estimated rotation angle is of the order of <1 degree, but can be detected with an extinction ratio of polarization of >30 dB. We examined the effects of the optical path length of repeating square mirror optics and an air-gap length of the discharge on the rotation angle. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(4): 1–7, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20689 [ABSTRACT FROM AUTHOR]

Abstract Caustics produce beautiful and intriguing illumination patterns. However, their complex behavior makes them difficult to simulate accurately in all but the simplest configurations. To capture their appearance, we present an adaptive approach based upon light beams. Exploiting the coherence between the light rays forming a beam greatly reduces the number of samples required for precise illumination reconstruction. The beams characterize the light distribution due to interactions with specular surfaces in 3D space. They thus allow for the treatment of illumination within single-scattering participating media. A hierarchical structure enclosing the light beams possesses inherent properties to detect efficiently all beams reaching any 3D point, to adapt itself according to illumination effects in the final image, and to reduce memory consumption via caching. [ABSTRACT FROM AUTHOR]

The design of an orthogonal circular polarization axicon beam splitter (OCPABS) that generates orthogonal circular polarization states (OCPS) is presented. The OCPABS consists of an absorbing V-shaped substrate coated with a transparent single-layer thin film. The power reflectances range between 25.19 and 56.24% in the infrared (IR), visible, and ultraviolet (UV) light regions. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 260–265, 2001. [ABSTRACT FROM AUTHOR]

The design of a polarization beam splitter for visible light (PBS–VL) is presented. The PBS–VL consists of an absorbing substrate coated with a double layer of transparent thin films. The PBS–VL power reflectances for the p- and s-polarizations are in the range of 70 and 97%, respectively. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 51–55, 2001. [ABSTRACT FROM AUTHOR]

The design of a reflective axicon polarization beam splitter (APBS) for a UV light is presented. The APBS consists of an absorbing substrate coated with a single-layer thin film. Two different materials are used as a substrate for the APBS. The APBS power reflectances for the p- and s-polarizations are in the range of 87 and 97%, respectively, for both materials. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 223–229, 2000 [ABSTRACT FROM AUTHOR]

Based on Moharam's field modulation function and the coupled-wave equations, exact analytic straight and parametric expressions are deduced for the steady state of dynamic two-beam coupling with any constant values of light intensity modulation and light excitation efficiency. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 278–283, 2000. [ABSTRACT FROM AUTHOR]

Objective To develop an interstitial laser light delivery system using multiple optical fibres for photodynamic therapy (PDT) in the treatment of prostate cancer. Patients and methods A laser beam was divided equally with a 1×4 fibre splitter to deliver PDT simultaneously through four 2-cm long, flexible cylindrical optical diffusers. Biplanar transrectal ultrasonography (TRUS) and a template were used to position the optical fibres percutaneously. In vivo measurements of light penetration depth (1/μeff ) in prostate tissue were made in seven patients, using a sheathed isoprobe to measure light fluence rates at varying radial distances from the diffuser. The prostate was fixed with stabilization needles to minimize displacement during needle placement. Results The mean (sd, range) μeff in the prostates of the seven patients was 0.35 (0.07, 0.22–0.44) mm-1 , which produced closely parallel slopes of light attenuation. However, there was up to a 10-fold variation in absolute light levels at the same diffuser–detector separation distances amongst the seven patients, probably caused by blood pooling around the diffuser light source. A similar problem around the isoprobe detector was overcome by sheathing the probe in clear plastic tubing. By stabilizing the prostate, the optical fibre positioning was precise to within 2 mm. Conclusion Although this light delivery and TRUS assembly were developed for clinical PDT in the prostate, the same instrumentation can be used reliably for in vivo light-penetration studies. Haemorrhage was unpredictable and highlighted one of the main problems which needs to be overcome. [ABSTRACT FROM AUTHOR]

The optical set-up for a (2,L) SW-banyan network, which is based on polarizing beam splitters and ID phase spatial light modulators, is proposed and demonstrated, and its corresponding routing control for the routing path between any source-destination pair has been discussed. The proposed optical setup consists of only optical polarization elements, it is compact in structure its corresponding energy loss and cross talk an" low, and its available number of channels is high. [ABSTRACT FROM AUTHOR]

We report a technique for measuring the spatial profile of microwave-frequency currents in resonant thin-film superconducting microstrip devices operated near resonance. We probe the patterned superconducting device as a function of position by scanning a modulated light beam across, the region to be probed. With the light focused to a spot size much smaller than the microstrip width, we have measured the current density distribution as a function of position across the width of the strip, Using an elementary model for the superconducting current density distribution, we fit an effective penetration depth at the edge of the microstrip. [ABSTRACT FROM AUTHOR]

In the proposed system, a phase hologram is uploaded to the SLM and the holographic lens 4f system filters the multi-order diffraction image of the phase hologram. International Conference on Display Technology 2020 (Volume 52, Issue S1) 477 Optical see-through near-eye 3D display based on holographic lens 4f system Min-Yang He*, Yan Xing*, Huan Deng**, Han-Le Zhang*, ** and Qiong-Hua Wang*, *** *School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China **School of Electronics and Information Engineering, Sichuan University, Chengdu 610065, China Optical see-through near-eye 3D display is one of the augmented reality (AR) display technologies, and it integrates virtual 3D information with real 3D scenes to the retina [1]. P-3.1: Optical see-through near-eye 3D display based on holographic lens 4f system. [Extracted from the article]