Showing papers on "Beam splitter published in 2005"

Matter-wave interferometry in a double well on an atom chip

Abstract: Matter-wave interference experiments enable us to study matter at its most basic, quantum level and form the basis of high-precision sensors for applications such as inertial and gravitational field sensing. Success in both of these pursuits requires the development of atom-optical elements that can manipulate matter waves at the same time as preserving their coherence and phase. Here, we present an integrated interferometer based on a simple, coherent matter-wave beam splitter constructed on an atom chip. Through the use of radio-frequency-induced adiabatic double-well potentials, we demonstrate the splitting of Bose–Einstein condensates into two clouds separated by distances ranging from 3 to 80 μm, enabling access to both tunnelling and isolated regimes. Moreover, by analysing the interference patterns formed by combining two clouds of ultracold atoms originating from a single condensate, we measure the deterministic phase evolution throughout the splitting process. We show that we can control the relative phase between the two fully separated samples and that our beam splitter is phase-preserving.

Linear Optics Controlled-Phase Gate Made Simple

Abstract: Linear optics quantum logic gates are the best tool to generate multiphoton entanglement. Simplifying a recent approach, we were able to implement the conditional phase gate with only one second-order interference at a polarization dependent beam splitter, thereby significantly increasing its stability. The improved quality of the gate is evaluated by analyzing its entangling capability and by performing full process tomography. The achieved results ensure that this device is well suited for implementation in various multiphoton quantum information protocols.

Demonstration of a Simple Entangling Optical Gate and Its Use in Bell-State Analysis

Abstract: We demonstrate a new architecture for an optical entangling gate that is significantly simpler than previous realizations, using partially polarizing beam splitters so that only a single optical mode-matching condition is required. We demonstrate operation of a controlled-z gate in both continuous-wave and pulsed regimes of operation, fully characterizing it in each case using quantum process tomography. We also demonstrate a fully resolving, nondeterministic optical Bell-state analyzer based on this controlled-z gate. This new architecture is ideally suited to guided optics implementations of optical gates.

Double-pass acousto-optic modulator system

Abstract: A practical problem that arises when using acousto-optic modulators (AOMs) to scan the laser frequency is the dependence of the beam diffraction angle on the modulation frequency Alignment problems with AOM-modulated laser beams can be effectively eliminated by using the AOM in the double-pass configuration, which compensates for beam deflections On a second pass through the AOM, the beam with its polarization rotated by 90° is deflected back such that it counterpropagates the incident laser beam and it can be separated from the input beam with a polarizing beam splitter Here we present our design for a compact, stable, double-pass AOM with 75% double-pass diffraction efficiency and a tuning bandwidth of 68 MHz full width at half maximum for light transmitted through a single-mode fiber The overall efficiency of the system (defined as the optical power out of the single-mode fiber divided by the optical power into the apparatus) is 60%

X-ray wavefront analysis and optics characterization with a grating interferometer

Abstract: We present an interferometric method to measure the shape of a hard-x-ray wavefront. The interferometer consists of a phase grating as a beam splitter and an absorption grating as a transmission mask for the detector. The device can be used to measure wavefront shape gradients corresponding to radii of curvature as large as several dozens of meters, with a lateral resolution of a few microns. This corresponds to detected wavefront distortions of approximately 10−12m or λ∕100. The device was used with 12.4 keV x rays to measure the slope error and height profile of an x-ray mirror. Surface slope variations with periods ranging from less than 1 mm to more than 1 m can be detected with an accuracy better than 0.1μrad.

Simple high efficiency optical coherence domain reflectometer design

Abstract: The present invention discloses simple and yet highly efficient configurations of optical coherence domain reflectometry systems. The combined use of a polarizing beam splitter (614a) with one or two polarization manipulator(s) (634a and 646) (e.g. a Faraday rotator or a quarter wave plate) that rotate the returned light wave polarization to an orthogonal direction, enables one to achieve high optical power delivery efficiency as well as fixed or predetermined output polarization state of the interfering light waves reaching a detector (652a) or detector array, which is especially beneficial for spectral domain optical coherence tomography. In addition, the system can be made insensitive to polarization fading resulting from the birefringence change in the sample (620a) and reference (622a) arms. Dispersion matching can also be easily achieved between the sample and the reference arm for high resolution longitudinal scanning.

Quantitative analysis of surface plasmon interaction with silver nanoparticles.

Abstract: The present insight into plasmon effects on the nanoscale seems sufficiently advanced to allow the development of surface-plasmon-polariton- (SPP-) based optical devices. Therefore quantitative information describing SPP phenomena is required. We investigate a SPP beam splitter constituted by silver nanoparticles on a silver thin film, fabricated by electron-beam lithography. We acquire quantitative information on the beam splitter performance by monitoring SPP leakage radiation, yielding SPP reflection, transmission, and scattering efficiencies.

Wire-grid diffraction gratings used as polarizing beam splitter for visible light and applied in liquid crystal on silicon

Abstract: The application of wire grid polarizers as efficient polarizing beam splitters for visible light is studied. The large differences between the transmissivity for different polarizations are explained qualitatively by using the theory of metallic wave guides. The results of rigorous calculations obtained by using the finite element method are compared with experiments for both classical and conical mount. Furthermore the application of wire-grid polarizers in liquid crystal on silicon display systems is considered.

Shearing Interferometer for Quantifying the Coherence of Hard X-Ray Beams

Abstract: We report a quantitative measurement of the full transverse coherence function of the 14.4 keV x-ray radiation produced by an undulator at the Swiss Light Source. An x-ray grating interferometer consisting of a beam splitter phase grating and an analyzer amplitude grating has been used to measure the degree of coherence as a function of the beam separation out to 30 μm. Importantly, the technique provides a model-free and spatially resolved measurement of the complex coherence function and is not restricted to high resolution detectors and small fields of view. The spatial characterization of the wave front has important applications in discovering localized defects in beam line optics

Design of a compact photonic-crystal-based polarizing beam splitter

Abstract: A compact polarizing beam splitter based on a photonic crystal (PC) directional coupler with a triangular lattice of air holes is designed and simulated. In the employed PC structure, transverse-electric (TE) light is confined with the photonic bandgap effect, while transverse-magnetic (TM) light is guided through an index-like effect. Due to the different guiding mechanisms, TM and TE light have strikingly different beat lengths, which is utilized to separate the two polarizations in a directional coupler no longer than 24.2 /spl mu/m. The two-dimensional finite-difference time-domain method of computation is used to evaluate the device performance. The extinction ratios are found to be around 20 dB for both TE and TM polarized light.

Color sensing for laser decoating

Abstract: A coating removal apparatus utilizing a common optics path to provide laser pulses to a coated surface and to direct a light illumination reflected from the coated surface to a photosensitive detector and analyzer. The apparatus is an integrated device including a laser source, a beam splitter, scanning optics, a waste removal apparatus, one or more light illuminators, a photosensitive detector, a comparator, and a control logic circuit. Alternatively, the laser source is external to the integrated device and a fiber optic cable is used to connect the laser source to the integrated device.

Conditional generation of arbitrary single-mode quantum states of light by repeated photon subtractions

Abstract: We propose a scheme for the conditional generation of arbitrary finite superpositions of Fock states in a single mode of a traveling optical field. The setup requires a source of squeezed vacuum states, beam splitters, strong coherent beams, photodetectors with single-photon sensitivity, and a final squeezer. If we want to generate a squeezed superposition of Fock states, which is sufficient in several applications, then the last squeezer is not even needed. The thrust of this method is that it achieves a high fidelity without requiring photodetectors with a high efficiency or a single-photon resolution. The possibility to improve its scaling by using a quantum memory is also discussed.

Miniature fourier transform spectrophotometer

Abstract: The Miniature Fourier Transform Spectrophotometer provides the capability, in a miniaturized device, of determining the light absorption/transmission spectra of a collected sample of gas or liquid though Fourier Transform spectroscopy techniques. The device takes an optical input from an optical fiber, manipulates that light through miniature optical components, and launches it into a miniaturized Michelson interferometer with a scanning mirror that acquires the interferogram of the optical input. The interferogram can be processed to retrieve the spectrum of the input light. A novel multi-stepped micro-mirror operates as the optical path length modulator in the miniaturized interferometer. A unique monolithic beamsplitter/mirror combination provides for accurate alignment of the components and greatly simplifies product integration. The device is designed to cover various optical spectra of interest. During operation, the precision and accuracy of the microfabricated components in the device allow operation and resolution even at extremely low wavelengths. In addition, the miniaturized nature of the device allows it to be used in new and extremely space-constrained applications.

Multiplexing Spectrum Interference Optical Coherence Tomography

Abstract: It is possible to realize a multiplexing spectrum interference optical coherence tomography enabling OCT measurement of full range having no delay of measurement time attributed to high-degree scan and not containing any complex conjugate image. The multiplexing spectrum optical interference optical coherence tomography includes: a first beam splitter (3) arranged on the optical path (2) from a light source (1) for separating an object light (4) from a reference light (5); a galvano mirror (6) arranged on the optical path of the object light (4) for scanning the object light on a measurement object (8); a second beam splitter (10) arranged on the optical path of the reference light (5); a first reference mirror (12) arranged on the optical path of the first reference light (11) separated by the second beam splitter (10); a second reference mirror (15) arranged on the optical path of the second reference light (13) separated by the second beam splitter (10); and a chopper (16) for alternately transmitting the first reference light (11) and the second reference light (13).

Broadband polarizing beam splitter with an embedded metal-wire nanograting

Abstract: An embedded metal-wire nanograting is designed and fabricated for the first time to our knowledge. This artificial material could be used as a broadband polarizing beam splitter to reflect s-polarized light and transmit p-polarized light. An upper-cladding layer of the same material as the gratings is deposited on the ridge of the gratings, whereas the metal wire is deposited in the grating trenches. This embedded structure makes the grating more firm in its applications. High polarization efficiency and low insertion loss with a broad wavelength range (900–1700?nm) and a wide angular tolerance are obtained by optimization of the designed structure.

Multi-channel, multi-spectrum imaging spectrometer

Abstract: A multi-spectrum, multi-channel imaging spectrometer includes two or more input slits or other light input devices, one for each of two or more input channels. The input slits are vertically and horizontally displaced, with respect to each other. The vertical displacements cause spectra from the two channels to be vertically displaced, with respect to each other, on a single image sensor on a stationary image plane. The horizontal displacements cause incident light beams from the respective input channels to strike a convex grating at different respective incidence angles and produce separate spectra having different respective spectral ranges. A retroflective spectrometer includes a convex grating that, by diffraction, disperses wavelengths of light at different angles and orders approximately back along an incident light beam. A single concave mirror reflects both the input channel and the dispersed spectrum. A prism, set of mirrors, beam splitters or other optical element(s) folds the input channel(s) of a spectrometer to enable the input(s) to be moved away from the plane of the image sensor, thereby enabling a large camera or other device to be attached to the spectrometer without blocking the input(s). A mounting mechanism enables a curved optical element to be adjusted through lateral and transverse translations, without requiring a gimbal mount.

Monitor for showing high-resolution and three-dimensional images and method

Abstract: A display system in which images from two displays that have the same optical polarization that is not affected by reflection by a beam splitter which combines images from the displays, and half wave plate optical retarders to rotate plane of polarization and to null out optical dispersion effects to provide for stereo viewing of images via plane polarizers that have the same polarization direction.

Simple, real-time method for removing the cyclic error of a homodyne interferometer with a quadrature detector system

Abstract: The cyclic error of a homodyne interferometer is caused mainly by phase mixing due to the imperfection of polarizing optical components such as polarizing beam splitters. In Appl. Opt.43, 2443 ( 2004), we concentrated on the relationship between these imperfect optical characteristics and the cyclic error and found the preamplifier-gains condition for removing the cyclic error. Here we demonstrate the cyclic error correction method experimentally and show that the method can be applied in real time. We obtained 0.04-nm cyclic errors, with a standard deviation above 5 µm.

Thin-film spatial filters

Abstract: A thin-film optical filter used as a one-dimensional spatial filter is presented, and its design is briefly examined. The filter consists of a stack of quarter-wave dielectric layers upon a right-angle prism that selectively cancel a reflected or transmitted plane-wave front for various angles of incidence. Transmittance and reflectance are low-pass functions or high-pass functions of the angle of incidence with a high degree of steepness. In combination, these filters exhibit bandpass transmittance with a variable bandwidth. Applications to detection of extrasolar planets are briefly discussed.

Quantum and classical correlations of intense beams of light investigated via joint photodetection

Abstract: We address joint photodetection as a method for discriminating between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin beam obtained by parametric down-conversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent for several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump laser fluctuations.

Self-synchronous locking of optical coherence by single-detector electronic-frequency tagging

Abstract: A coherent laser beam combining system wherein the output of a single master oscillator is split into a plurality of signals, the signals are electronically modulated at unique frequencies. One signal is designated a reference signal while the remaining signals are passed through phase adjusters. All signals are optically amplified, aligned and passed through a beam splitter to split off a small sample that is imaged onto a photodetector. The photodetector output is fed to a signal processor that produces phase error signals that drive the phase adjusters resulting in a high-powered optically coherent output signal.

Imaging system, image data stream creation apparatus, image generation apparatus, image data stream generation apparatus, and image data stream generation system

Abstract: An imaging system that is capable of generating high resolution and high frame rate video includes of a beam splitter, two lenses, a high resolution-low frame rate camera, and a low resolution-high frame rate camera. The beam splitter reflects a part of an incident ray. The two lenses gather the ray reflected from the beam splitter and the ray penetrating the beam splitter, respectively. The low resolution-high frame rate camera is a sensor that takes an image of the ray gathered by one of the lenses at a low resolution and a high frame rate. The high resolution-low frame rate camera is a sensor that takes an image of the ray gathered by the other of the lenses at a high resolution and a low frame rate.

Polarization control and sensing with two-dimensional coupled photonic crystal microcavity arrays

Abstract: We have experimentally studied polarization properties of the two-dimensional coupled photonic crystal microcavity arrays and observed a strong polarization dependence of the transmission and reflection of light from the structures-effects that can be employed in building miniaturized polarizing optical components. Moreover, by combining these properties with a strong sensitivity of the coupled bands on the surrounding refractive index, we have demonstrated a detection of small refractive-index changes in the environment, which is useful for construction of biochemical sensors.

Polarization beam splitters based on a two-dimensional photonic crystal of negative refraction

Abstract: Polarization beam splitters based on a two-dimensional photonic crystal of negative refraction

Micromachined Fourier transform spectrometer on silicon optical bench platform

Abstract: We present a miniaturized Fourier transform spectrometer implemented on a silicon optical bench platform. The optical and opto-mechanical components of a Michelson interferometer, such as a beam splitter, micromirrors, MEMS actuators, and fiber U-grooves, are simultaneously fabricated by micromachining of the device layer of a silicon-on-insulator wafer. Our bulk micromachining process combines the flexible definition capability of deep reactive ion etching with the good surface quality provided by anisotropic KOH wet-etching. A spectral resolution of 45 nm near 1550 nm wavelength is demonstrated.

Scatterometry by phase sensitive reflectometer

Abstract: A phase-sensitive interferometric broadband reflectometer includes an illumination source for generating an optical beam. A beam splitter or other optical element splits the optical beam into probe beam and reference beam portions. The probe beam is reflected by a subject under test and then rejoined with the reference beam. The combination of the two beams creates an interference pattern that may be modulated by changing the length of the path traveled by the probe or reference beams. The combined beam is received and analyzed by a spectrometer.

A polarizing beam splitter using negative refraction of photonic crystals

Abstract: Light passing through a photonic crystal can undergo a negative or a positive refraction. The two refraction states can be functions of the contrast index, the incident angle and the slab thickness. By suitably using these properties it is possible to realize very simple and very efficient optical components to route the light. As an example we present a passive device acting as a polarizing beam splitter where TM polarization is refracted in positive direction whereas TE component is negatively refracted.

Multiphoton entanglement through a Bell-multiport beam splitter

Abstract: Multiphoton entanglement is an important resource for linear optics quantum computing. Here we show that a wide range of highly entangled multiphoton states, including $W$-states, can be prepared by interfering single photons inside a Bell multiport beam splitter and using postselection. A successful state preparation is indicated by the collection of one photon per output port. An advantage of the Bell multiport beam splitter is that it redirects the photons without changing their inner degrees of freedom. The described setup can therefore be used to generate polarization, time-bin, and frequency multiphoton entanglement, even when using only a single photon source.

Quantum and classical correlations of intense beams of light via joint photodetection

Abstract: We address joint photodetection as a method to discriminate between the classical correlations of a thermal beam divided by a beam splitter and the quantum entanglement of a twin-beam obtained by parametric downconversion. We show that for intense beams of light the detection of the difference photocurrent may be used, in principle, in order to reveal entanglement, while the simple measurement of the correlation coefficient is not sufficient. We have experimentally measured the correlation coefficient and the variance of the difference photocurrent on several classical and quantum states. Results are in good agreement with theoretical predictions taking into account the extra noise in the generated fields that is due to the pump-laser fluctuations.

Event-based simulation of single-photon beam splitters and Mach-Zehnder interferometers

Abstract: We demonstrate that networks of locally connected processing units with a primitive learning capability exhibit a behavior that is usually only attributed to quantum systems. We describe networks that simulate single-photon beam splitter and Mach-Zehnder interferometer experiments on a causal, event-by-event basis and demonstrate that the simulation results are in excellent agreement with quantum theory.