Showing papers on "Beam splitter published in 2004"

The On-Orbit Performance of the Galaxy Evolution Explorer

Abstract: We report the first year on-orbit performance results for the Galaxy Evolution Explorer (GALEX), a NASA Small Explorer that is performing a survey of the sky in two ultraviolet bands. The instrument comprises a 50 cm diameter modified Ritchey-Chretien telescope with a 1.25 degree field of view, selectable imaging and objective grism spectroscopic modes, and an innovative optical system with a thin-film multilayer dichroic beam splitter that enables simultaneous imaging by a pair of photon counting, microchannel plate, delay line readout detectors. Initial measurements demonstrate that GALEX is performing well, meeting its requirements for resolution, efficiency, astrometry, bandpass definition and survey sensitivity.

Quantum beat of two single photons.

Abstract: The interference of two single photons impinging on a beam splitter is measured in a time-resolved manner. Using long photons of different frequencies emitted from an atom-cavity system, a quantum beat with a visibility close to 100% is observed in the correlation between the photodetections at the output ports of the beam splitter. The time dependence of the beat amplitude reflects the coherence properties of the photons. Most remarkably, simultaneous photodetections are never observed, so that a temporal filter allows one to obtain perfect two-photon coalescence even for nonperfect photons.

Polarization splitter in three-core photonic crystal fibers.

Abstract: A novel design of polarization splitter in three-core photonic crystal fibers (PCFs) has been proposed. The three-core PCF consists of two given identical cores with two-fold symmetry separated by a core with high birefringence. The polarization splitter is based on the phenomenon of resonant tunneling. Numerical simulations with a full vectorial beam propagation method demonstrate that it is possible to obtain a 1.9-mm-long splitter with the extinction ratio better than -20 dB and a bandwidth of 37 nm.

Dispersion-based beam splitter in photonic crystals.

Abstract: A novel implementation of a dispersion-based beam splitter in a photonic crystal (PhC) is proposed. The beam splitter consists of two periodic structures: a nonchannel dispersion-guiding region and a splitting structure operating inside the photonic bandgap. The dispersion-guiding PhC structure is used to route the optical wave by exploiting the dispersion properties of the lattice. An arbitrary power ratio between the output beams can be achieved by varying the parameters of the splitting structure. Within the studied range of splitting structures, high output power was observed and verified experimentally.

Multipartite continuous-variable entanglement from concurrent nonlinearities

Abstract: We show theoretically that concurrent interactions in a second-order nonlinear medium placed inside an optical resonator can generate multipartite entanglement between the resonator modes. We show that there is a mathematical connection between this system and van Loock and Braunstein's proposal for entangling $N$ continuous quantum optical variables by interfering with the outputs of $N$ degenerate optical parametric amplifiers (OPA) at a $N$-port beam splitter. Our configuration, however, requires only one nondegenerate OPA and no interferometer. In a preliminary experimental study, we observe the concurrence of the appropriate interactions in periodically poled ${\mathrm{RbTiOAsO}}_{4}$.

High-throughput, high-damage-threshold broadband beam splitter for high-order harmonics in the extreme-ultraviolet region

Abstract: We demonstrate a high-throughput and high-damage-threshold beam splitter for high-order harmonics in the soft-x-ray region that uses Si and (or) SiC plates set at Brewster's angle with respect to the pump wavelength. The beam splitters are guaranteed to have a damage threshold of at least 0.8 TW/cm2 (average power density, 0.25 W/cm2) and an attenuation rate of 10(-4)-10(-5) for a 30-fs pump pulse. The measured reflection efficiency at the 27th harmonic (29.6 nm) was 0.56 for Si and 0.45 for SiC. These beam splitters are useful not only for high harmonics but also for longitudinally pumped x-ray lasers.

Raman spectroscopy system and method and specimen holder therefor

Abstract: A Raman spectroscopy system includes a laser source for providing a laser beam, and an optical probe assembly including a photonic crystal fiber light guide for receiving the laser beam from the laser source and for directing the laser beam toward a specimen of selected material, a lens for receiving the laser beam in the light guide and directing the beam onto the specimen and for receiving reflected light from the specimen and directing the reflected light back through the fiber light guide, and a dichroic beam splitter for directing a portion of the reflected beam out of the optical probe assembly. The system further includes an optical spectrum analyzer for receiving the portion of the reflected beam and for exhibiting a Raman signature of the specimen.

Analysis of splitters for self-collimated beams in planar photonic crystals

Abstract: In this paper, we present methods for beam splitting in a planar photonic crystal, where the light is self-guided as dictated by the selfcollimation phenomenon. We present an analysis of a one-to-two and one-to-three beam splitter in a self-guiding photonic crystal lattice and validate our design and simulations with experimental results. Moreover, we present the first one-to-three splitter in a self-guiding planar photonic crystal. Additionally, we discuss the ability to tune the properties of these devices and present initial experimental results.

Portable system for detecting skin abnormalities based on characteristic autofluorescence

Abstract: A lightweight hand-held skin abnormality detection system includes a source of excitation light that causes tissue under examination to produce fluorescence light. The fluorescence light produced along with the beam of reference light is provided to a beam splitter which divides the fluorescence light and the reference light into separate optical channels. Each optical channel produces an image of the tissue under examination. A passive optical combiner superimposes the image produced by each optical channel for viewing by a user.

Agile high sensitivity optical sensor

Abstract: An agile optical sensor based on scanning optical interferometry is proposed. The preferred embodiment uses a retroreflective sensing design while another embodiment uses a transmissive sensing design. The basic invention uses wavelength tuning to enable an optical scanning beam and a wavelength dispersive element like a grating to act as a beam splitter and beam combiner to create the two beams required for interferometry. A compact and environmentally robust version of the sensor is an all-fiber in-line low noise delivery design using a fiber circulator, optical fiber, and fiber lens connected to a Grating-optic and reflective sensor chip.

Multimode interference-based photonic crystal waveguide power splitter

Abstract: A compact power splitter based on the multimode interference (MMI) effect in photonic crystal waveguides is designed and analyzed. The device size reduction compared with the conventional MMI power splitter can be attributed to the large dispersion of the photonic crystal waveguides. The Massachusetts Institute of Technology Photonic-Bands code is used to calculate the band structures of photonic crystal waveguides. The finite-difference time-domain method is adopted to simulate the relevant structures.

Planar photonic crystal polarization splitter.

Abstract: The differential dispersion relation for the E and H modes (TM-like and TE-like, respectively) in planar photonic crystals is used to control the polarization-dependent propagation of light. E- and H-polarized beams were separated by 10 degrees after propagating through a 20-microm-long planar photonic crystal in the wavelength range from 1250 to 1300 nm. The plane-wave expansion calculation matches well with the experimental results. This result represents the first demonstration, to our knowledge, of a polarization splitter realized in a planar photonic crystal configuration in the near-infrared wavelength range operating solely in transmission mode.

Generation of macroscopic superposition states with small nonlinearity

Abstract: We suggest a scheme to generate a macroscopic superposition state (Schrodinger cat state) of a free-propagating optical field using a beam splitter, homodyne measurement, and a very small Kerr nonlinear effect. Our scheme makes it possible to reduce considerably the required nonlinear effect to generate an optical cat state using simple and efficient optical elements.

Quantum Theory of Atom-Wave Beam Splitters and Application to Multidimensional Atomic Gravito-Inertial Sensors

Abstract: We review the theory of atom-wave beam splitters using atomic transitions induced by electromagnetic interactions. Both the spatial and temporal dependences of the e.m.3 fields are introduced in order to compare the differences in momentum transfer which occur for pulses either in the time or in the space domains. The phases imprinted on the matter-wave by the splitters are calculated in the limit of weak e.m. and gravitational fields and simple rules are derived for practical atom interferometers. The framework is applicable to the Lamb-Dicke regime. Finally, a generalization of present 1D beam splitters to 2D or 3D is considered and leads to a new concept of multidimensional atom interferometers to probe inertial and gravitational fields especially well-suited for space experiments.

Polarizing beam splitter assembly adhesive

Abstract: A polarizing beam splitter (PBS) includes a multilayer reflective polarizing film, a pressure sensitive adhesive is disposed on the multilayer reflective polarizing film, a first rigid cover is disposed on the pressure sensitive adhesive. The PBS can be used in a variety of applications.

Opthalmic talbot-moire wavefront sensor

Abstract: A system for measuring the eye comprising a light source (10) which sends a narrow collimated beam of light (12), to reflect from a beam splitter (14). The beam of light (12) enters the eye (16) through the pupil (17) where it is focused to a point (20) on the retina (18). The light (12) is reflected from the retina (18) where it passes through a series of relay lenses (22, 24). The light then passes through one or more reticles (26, 28). A CCD camera (30) records the shadow pattern formed by reticles (26, 28). The shadow pattern is digitized into a computer and algorithms are created to calculate the distortions. As a result of the above steps being performed, the refractive power of the eye, with or without corrective lenses in place, can be measured at many points, simultaneously.

Polarizing beam splitter and projection systems using the polarizing beam splitter

Abstract: A polarizing beam splitter (PBS) includes a first multilayer reflective polarizing film and a second multilayer reflective polarizing film disposed between two covers. The two multilayer reflective polarizing films can be the same or different. The PBS can be used in a variety of applications.

Optimal quantum cloning on a beam splitter.

Abstract: We demonstrate how a beam splitter in combination with different light sources can be used as an optimal universal 1 ! 2 quantum cloner and as an optimal universal quantum NOT machine for the polarization qubit of a single photon. For the cloning a source of single photons with maximally mixed polarization is required and for the NOT operation a source of maximally entangled photon pairs. We demonstrate both operations with near optimal fidelity. Our scheme can be generalized in a natural way to clone and NOT the spin state of electrons.

Photonic crystal beam splitters.

Abstract: This work studies two-dimensional photonic crystal beam splitters with two input ports and two output ports. The beam splitter structure consists of two orthogonally crossed line defects and one point defect in square-lattice photonic crystals. The point defect is positioned at the intersection of the line defects to divide the input power into output ports. If the position and the size of the point defect are varied, the power of two output ports can be identical. The beam splitters can be used in photonic crystal Mach-Zehnder interferometers or switches. The simulation results show that a large bandwidth of the extinction ratio larger than 20 dB can be obtained while two beams are interfered in the beam splitters. This enables photonic crystal beam splitters to be used in fiber optic communication systems.

Optical connector adapter for interfacing a beam splitter/combiner to optical waveguides and method of forming the same

Abstract: An optical connector adapter includes a substrate having at least one optical waveguide for transporting optical signals. The substrate includes opposing ends, a top reference surface and side reference surface aligned relative to the at least one optical waveguide. A respective carrier bracket is received over each end of the substrate. Substrate alignment fiducials align the carrier brackets relative to the substrate. The substrate carrier receives the substrate and carrier brackets. Respective carrier alignment fiducials align the substrate carrier and the carrier brackets. A beam splitter/combiner is positioned at each end of the substrate and receives and couples an optical signal into the at least one optical waveguide.

Removing nonlinearity of a homodyne interferometer by adjusting the gains of its quadrature detector systems.

Abstract: Most homodyne interferometers have a quadrature detector system that includes two polarizing beam splitters that cause nonlinearity of the order of a few nanometers by phase mixing Detectors should have the same gains to reduce nonlinearity under the assumption that there is no loss in optical components However, optical components exhibit some loss We show that nonlinearity can be reduced to an order of 001 nm when the detector gains are adjusted by simulation to include the optical characteristics The compensated nonlinearity is 18 times smaller than that when the four detector gains are set to be equal

Polarization-selective beam splitter based on a highly efficient simple binary diffraction grating

Abstract: A polarization beam splitter (PBS) based on a giant-reflection to zero-order (GIRO) grating is presented. The GIRO grating is a simple binary diffraction grating with parameters chosen such that the excited optical modes in the grating interfere constructively and destructively at the respective interfaces. This interference results in high-zero-order reflection (>99%) with a high polarization-selective extinction ratio (±30 dB). The grating shows a low aspect ratio. The GIRO PBS is theoretically and experimentally shown to be an adequate PBS for use as an optical isolator in combination with a quarter-wave plate in a CO2-laser system.

Superresolution laser beam shaping

Abstract: The superresolution technique is well known for its ability to compress the central diffractive spot that is smaller than the Airy diffractive spot. In this paper, we extend the superresolution technique for different laser beam shaping. A complete set of superresolution diffractive elements is developed for the flat-top beam shaping, the single-circle beam shaping, and the novel circular Dammann grating. Five phase plates, corresponding to each of its applications, have been made by use of micro-optics technology. Experiments that are presented are in good agreement with the theoretical results. The superresolution technique presented in this paper should be highly interesting for the wide applications of laser beam shaping.

Broadband polarizing beam splitter based on the form birefringence of a subwavelength grating in the quasi-static domain.

Abstract: We propose a novel broadband polarizing beam splitter with a compact sandwich structure that has a subwavelength grating in the quasi-static domain as the filling. The design is based on effective-medium theory an anisotropic thin-film theory, and the performance is investigated with rigorous coupled-wave theory. The design results show that the structure can provide a high polarization extinction ratio in a broad spectral range.

Quantum interference of ultrastable twin optical beams.

Abstract: We report the first measurement of the quantum phase-difference noise of an ultrastable nondegenerate optical parametric oscillator that emits twin beams classically phase locked at exact frequency degeneracy. The measurement illustrates the property of a lossless balanced beam splitter to convert number-difference squeezing into phase-difference squeezing, and thus provides indirect evidence for Heisenberg-limited interferometry using twin beams. This experiment is a generalization of the Hong-Ou-Mandel interference effect for continuous variables and constitutes a milestone towards continuous-variable entanglement of bright, ultrastable nondegenerate beams.

Depth-enhanced integral imaging by use of optical path control.

Abstract: The image depth of integral imaging is enhanced by doubling the number of central depth planes by use of optical path control. To accomplish this, the optical path lengths are changed by controlling whether reflections occur behind the lens array. We propose three schemes that use mirrors, a combination of beam splitters and polarizers, and polarization beam splitters, respectively. In experiments we implement the systems that are completely electronically controllable, are compact, and provide two central depth planes with 50.4-mm separation.

Pinhole interferometry with coherent hard X-rays.

Abstract: This paper discusses the experimental realisation of two types of X-ray interferometer based on pinhole diffraction. In both interferometers the beam splitter was a thin metal foil containing micrometer pinholes to divide the incident X-ray wave into two coherent waves. The interference pattern was studied using an energy-dispersive detector to simultaneously investigate in a large spectral range the diffraction properties of the white synchrotron radiation. For a highly absorbing pinhole mask the interference fringes from the classical Young's double-pinhole experiment were recorded and the degree of coherence of X-rays could be determined. In the case of low absorption of the metal foil at higher X-ray energies (>15 keV) the interference pattern of a point diffraction interferometer was observed using the same set-up. The spectral refraction index of the metal foil was determined.

Optical detection system with polarizing beamsplitter

Abstract: An optical detection system for use in flow cytometry or the like, which includes a polarizing beamsplitter 820 such as a Wollaston prism. A light source provides an input light beam to a flow stream, wherein the input light beam has a polarization direction. The particles in the flow stream may produce an output light beam that includes a polarized component and a depolarized component. The polarizing beamsplitter receives the output light beam, and provides a polarized light beam and a depolarized light beam to a pair of detectors. The pair of detectors provide a first output signal that corresponds to the polarized light beam and a second output signal that corresponds to the depolarized light beam. A controller or processor may use the first output signal and the second output signal to help identify/classify particles and/or particle characteristics in the flow stream.

Display device with capacity of displaying three-dimensional images

Abstract: A display device for selectively displaying any one of 2D and 3D images with a capacity of displaying the 3D image with the same resolution as that of the 2D image. The display device includes a light source radiating white colored light, and an image display unit receiving the light from the light source to display the desired images. A beam splitter is placed between the light source and the image display unit to split the light radiated from the light source in the directions of left and right eyes of the user, and feed the split light rays to the image display unit. An optical shutter is provided at any one of front and rear surfaces of the beam splitter. The optical shutter has a plurality of shutter members with variable light transmittance to control the light transmission such that at least one of the two-directional light rays split at the beam splitter reaches the user.

Gas discharge mopa laser spectral analysis module

Abstract: A spectral analysis module, including a wavemeter, for a high repetition rate gas discharge laser having a laser output beam comprising a pulsed output of greater than or equal to 15 mJ per pulse, sub-nanometer bandwidth tuning range pulses having a femptometer bandwidth precision and tens of femptometers bandwidth accuracy range, for measuring bandwidth on a pulse to pulse basis at pulse repetition rates of 4000 Hz and above, is disclosed which may comprise a primary beam-splitter in the path of the laser output laser of the gas discharge laser operative to pass the vast majority of the output beam and to reflect a first small portion of the output beam, the primary beam splitter oriented at an angle to sufficiently reduce the fluence on the primary beam-splitter, and creating overlapping fresnel reflections in the first small portion of the laser output beam; a secondary beam splitter made from a material having a damage threshold sufficiently high to tolerate the fluence created by the overlapping portion of the fresnel reflections in the first small portion of the output laser beam, the secondary beam splitter reflecting the vast majority of the first small portion of the output laser beam and passing a second small portion of the output laser beam; a telescoping optic in the path of the second small portion of the output beam operative to demagnify the second small portion of the output beam onto a first stage diffuser receiving the demagnified second small portion of the output laser beam, the demagnification selected to keep the fluence in the overlapping fresnel reflections in the second small portion of the output laser beam below the damage threshold of the first stage diffuser. The telescoping optic may demagnify a long axis of the second small portion of the output laser beam more than a short axis of the second small portion of the output laser beam, redistributing the fluence of the second small portion of the laser output beam across the first stage diffuser to keep any portion of the first stage diffuser from exceeding the damage threshold for the material from which the first stage diffuser is made. The vast majority of the first small portion of the laser output beam may be reflected into a power detection module. A second stage diffuser may creating a narrow cone of a focused second small portion of the laser output beam before the beam enters an interferometer.