Showing papers on "Polarization rotator published in 2005"

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.

A compact silicon-on-insulator polarization splitter

Abstract: A compact directional coupler-based polarization splitter is designed and realized using silicon-on-insulator (SOI) waveguides. Even though silicon does not have any material birefringence, the high index contrast obtained in the SOI platform and reduced waveguide dimensions makes it possible to induce significant birefringence. Polarization splitting is achieved by making use of this geometry-induced birefringence. In this work, we demonstrate polarization splitting in devices as short as 120 /spl mu/m. Even smaller devices can be made using submicron-thick Si waveguides.

Polarization Mode Dispersion

Abstract: to polarization mode dispersion in optical systems.- Modelling of polarization mode dispersion in optical communications systems.- Statistical properties of polarization mode dispersion.- Three Representations of Polarization Mode Dispersion.- The inverse PMD problem.- Numerical modeling of PMD.- Applications of importance sampling to polarization mode dispersion.- PMD & PDL.- Interaction of nonlinearity and polarization mode dispersion.- PMD measurement techniques and how to avoid the pitfalls.- PMD measurements on installed fibers and polarization sensitive components.- Reflectometric measurements of polarization properties in optical-fiber links.- PMD impact on optical systems: Single- and multichannel effects.- Polarization effects and performance of fiber optic recirculating loops.- PMD compensation techniques.- Low-PMD spun fibers.- PMD emulation.

Polarization microscopy by use of digital holography: application to optical- fiber birefringence measurements

Abstract: We present a digital holographic microscope that permits one to image polarization state. This technique results from the coupling of digital holographic microscopy and polarization digital holography. The interference between two orthogonally polarized reference waves and the wave transmitted by a microscopic sample, magnified by a microscope objective, is recorded on a CCD camera. The off-axis geometry permits one to reconstruct separately from this single hologram two wavefronts that are used to image the object-wave Jones vector. We applied this technique to image the birefringence of a bent fiber. To evaluate the precision of the phase-difference measurement, the birefringence induced by internal stress in an optical fiber is measured and compared to the birefringence profile captured by a standard method, which had been developed to obtain high-resolution birefringence profiles of optical fibers.

Polarization Optics in Telecommunications

Abstract: Vectorial Propagation of Light.- The Spin-Vector Calculus of Polarization.- Interaction of Light and Dielectric Media.- Elements and Basic Combinations.- Collimator Technologies.- Isolators.- Circulators.- Properties of Polarization-Dependent Loss and Polarization-Mode Dispersion.- Statistical Properties of Polarization in Fiber.- Review of Polarization Test and Measurement.

Design rules for slanted-angle polarization rotators

Abstract: A simple and general set of design rules for slanted-angle polarization-rotating waveguides is presented in this paper. These design rules are employed to construct single-mode SOI polarization rotators that offer significant advantages in conversion efficiency, optical loss, fabrication tolerance, spectral response and spatial dimensions relative to III-V components.

Generation of a radially polarized doughnut mode of high quality

Abstract: We present an experimental set-up to generate laser beams with locally varying polarization distribution. In a linear set-up, a radially polarized beam of high quality regarding intensity distribution, polarization and phase-front distortion is generated. This beam can be used for tight focusing. Further applications are discussed.

Polarization patterns hide and display using photoinduced anisotropy of photochromic fulgide

Abstract: Photoinduced anisotropy of a photochromic pyrrylfulgide/PMMA film was investigated by using two linearly polarized beams. Excitation by linearly polarized light induces into the film an optical axis that has the same polarization as the excitation beam. This causes a change of the transmittance and of the polarization state of the detection beam. With a microscope a matrix of 4×4 light spots with different polarizations were recorded in the pyrrylfulgide/PMMA film. If readout with non-polarized light, the matrix of light spots show no information pattern. However, when readout with differently polarized lights, different patterns can be displayed. The experiment demonstrates that pyrrylfulgide/PMMA films can be used to hide two differently polarized patterns, which may be applied in camouflage technology.

Polarization-selective grating mirrors used in the generation of radial polarization

Abstract: Two novel methods to control the polarization of laser radiation are presented. The discrimination between different polarization distributions isperformed with a corrugation grating in the top high-index layer of a multilayer mirror, which couples the undesired polarization into a lossy waveguidemode of the multilayer. The generation of radially polarized radiation in a laser resonator is presented as a practical verification of the principle.

Polarization effects in the diffraction of light by a planar chiral structure

Abstract: We analyze polarization changes of light diffracted on a planar chiral array from the standpoint of the Lorentz reciprocity lemma and find biorthogonality in the polarization eigenstates for waves diffracting though the grating in the opposite direction. Both reciprocal and nonreciprocal components in the polarization azimuth rotation of the diffracted light are identified. The structural chirality of the array arrangement and the chirality of individual elements of the array give rise to polarization effects.

Degree of polarization in tightly focused optical fields

Abstract: We analyze the degree of polarization of random, statistically stationary electromagnetic fields in the focal region of a high-numerical-aperture imaging system. The Richards-Wolf theory for focusing is employed to compute the full 3 x 3 electric coherence matrix, from which the degree of polarization is obtained by using a recent definition for general three-dimensional electromagnetic waves. Significant changes in the state of partial polarization, compared with that of the incident illumination, are observed. For example, a wave consisting of two orthogonal and uncorrelated incident-electric-field components produces rings of full polarization in the focal plane. These effects are explained by considering the distribution of the spectral densities of the three electric field components as well as the correlations between them.

Efficient polarization squeezing in optical fibers.

Abstract: We report on a novel and efficient source of polarization squeezing that uses a single pass through an optical fiber. Using the fiber's two orthogonal polarization axes produces two identical squeezed beams. Combining these in a Stokes measurement generates polarization squeezing of up to 5.1 +/- 0.3 dB. Furthermore, this scheme enables us to directly measure, for both polarizations, the noise of any given quadrature.

Optical birefringence and polarization dependent loss of square- and rectangular-lattice holey fibers with elliptical air holes: numerical analysis

Abstract: Polarization dependent leakage loss as well as optical birefringence for the fundamental mode in square- and rectangular-lattice holey fibers with elliptical air holes are studied numerically based on the full-vector finite element method for the first time. It is shown that high birefringence in the order of 10-2 and large polarization dependent loss required for single-polarization single-mode transmission are both achievable by using the proposed structure.

Polarization dynamics in vertical-cavity surface emitting lasers

Abstract: Experiments and their interpretation on polarization dynamics and polarization switching in vertical-cavity surface-emitting lasers operated in the fundamental transverse mode regime are reviewed. Important observations are switching events to a mode with the lower unsaturated gain and the existence of elliptically polarized dynamical transition states after the destabilization of the low-frequency polarization mode. The observations demonstrate the need to consider explicitly the phase properties of the optical field as well as nonlinear effects affecting polarization selection above threshold. Good qualitative agreement is found with a model which takes into account the spin degrees of freedom of the light field as well as of the carriers (`spin-flip model'), if the spin-flip rate is taken to be some tens of $10^9$~s$^{-1}$. This constitutes a strong -- though indirect -- indication that spin dependent processes are important in polarization selection in the devices investigated.

Cell parameter determination of a twisted-nematic liquid crystal display by single-wavelength polarimetry

Abstract: Optical transmittance of a 90-twisted nematic liquid crystal cell inserted between crossed or parallel polarizers is neither sensitive to the molecular twist sense nor to the exchange between the extraordinary and the ordinary birefringence axis at the input face of the cell. In this article, the equivalence between a twisted-nematic liquid crystal cell and the combination of a retardation wave plate and a polarization rotator is fully exploited to understand the physical origin of these ambiguities. We determine, in a simple way, cell parameters by means of standard cell transmittance measurements when both crossed and parallel polarizers are rotated simultaneously. We show that this procedure, which is subjected to the aforementioned ambiguities, can be completed by additional polarimetric measurements. In particular, we demonstrate that the twist angle, twist sense, retardation, and the rubbing direction can be univocally determined by experimental measurement of the Stokes parameters of the light tran...

Experimental investigation of the polarization properties of a hollow core photonic bandgap fiber for 1550 nm

Abstract: The properties of a hollow core photonic bandgap fiber designed for 1.55 um transmission are investigated with special emphasis on polarization issues. Large and strongly wavelength dependent phase and group delays are found. At the same time the principle states of polarization move strongly and erratically as a function of wavelength, leading to strong mode coupling. Wavelength regions with high polarization dependent loss coincide with depolarization due to a polarization dependent coupling to surface modes at these wavelengths.

High bandwidth single polarization fiber with elliptical central air hole

Abstract: A novel design of single polarization fiber is presented. The structure of the fiber comprises an elliptical central air hole with depressed cladding surrounding the core. Parameters that affect the performance of the single polarization fiber in terms of the location of the single polarization operating window and single polarization bandwidth are analyzed. The analysis results in the identification of a fiber design that can yield a single polarization bandwidth as high as 240 nm around 1550 nm.

Polarization conversion element, lighting optical device, exposure system, and exposure method

Abstract: A polarization conversion element capable of converting, with a limited light quantity loss, a linearly polarized incident light having a polarization direction in an almost single direction into a circumferentially polarized light having a polarization direction in an almost circumferential direction. A polarization conversion element (10) for converting the polarization state of an incident light into a specified polarization state. It is formed of an optical material having optical rotation, for example, quartz, and has a thickness distribution changing in a circumferential direction. The thickness distribution is so set that a linearly polarized light having a polarization direction in an almost single direction is converted into a circumferentially polarized light having a polarization direction in an almost circumferential direction. It has a plurality of circumferentially divided areas (10A-10D), and two arbitrary adjacent areas in the plurality of areas are different in thickness from each other. Also, two arbitrary facing areas in the plurality of areas have optical rotation angles almost equal to each other.

Polarization dynamics in installed fiberoptic systems

Abstract: This study monitors the polarization activity of operating light wave systems in urban and suburban areas. In 6 months of observation, multiple fast polarization fluctuations are detected, which are, however, not expected to trigger protection, or to affect performance of slower polarization mode dispersion (PMD) mitigating devices.

Space-variant polarization manipulation for far-field polarimetry by use of subwavelength dielectric gratings

Abstract: A method for polarimetric measurement that uses a discrete space-variant subwavelength dielectric grating is presented. One retrieves the polarization state by measuring the far-field intensity of a beam emerging from the grating followed by a polarizer. The analysis for a partially polarized, quasi-monochromatic beam is performed by use of the beam coherence polarization matrix along with an extended van Cittert–Zernike theorem. We experimentally demonstrate polarization measurements of both fully and partially polarized light.

Multistate polarization addressing using a single beam in an azo polymer film

Abstract: Peculiar light-matter interactions can break the rule that a single beam polarization can address only two states in an optical memory device. Multistate storage of a single beam polarization is achieved using self-induced surface diffraction gratings in a photoactive polymer material. The grating orientation follows the incident light beam's polarization direction. The permanent self-induced surface relief grating can be read out in real time using the same laser beam.

System and method converting the polarization state of an optical beam into an inhomogeneously polarized state

Abstract: A system for converting the polarization state of an optical beam which propagates along a path from an initial polarization state into an inhomogeneous polarization state includes a first isotropic material and a first anisotropic material. The first anisotropic material is positioned adjacent to the first isotropic material in a substantially transverse manner relative to the path of the optical beam. The first anisotropic material has a first alignment axis that produces one of a radially, azimuthally, and counter-rotationally polarized optical beam when substantially aligned with respect to a polarization axis of the optical beam.

Optical circuit device

Abstract: The present invention provide an optical circuit device having: an optical circuit; a polarization beam splitter/combiner for splitting an incoming light beam into two polarization beams and combining the two polarization beams into an outgoing light beam; a first optical waveguide and a second optical waveguide for connecting the optical circuit and the polarization beam splitter/combiner and receiving the two polarization beams independently; and a polarization rotator, arranged on the first optical waveguide, for rotating a polarization plane of one of the two polarization beams split by the polarization beam splitter/combiner so as to match a polarization plane of the other of the two polarization beams, the optical circuit, the polarization beam splitter/combiner, the first optical waveguide, the second optical waveguide and the polarization rotator being integrated on a planar substrate.

Characterization of bipartite states using a single homodyne detector

Abstract: We suggest a scheme to reconstruct the covariance matrix of a two-mode state using a single homodyne detector plus a polarizing beam splitter and a polarization rotator. It can be used to fully characterize bipartite Gaussian states and to extract relevant information on generic states.

Polarization distribution and degree of polarization for three-dimensional quantum light fields

Abstract: We introduce a probability distribution for polarization of three-dimensional quantum light fields as a marginal of the quadrature $Q$ function for a three-mode field by removing the variables irrelevant for polarization (total intensity and global phase). The probability distribution turns out to be determined by projection on SU(3) coherent states. We introduce a degree of polarization as the distance between the polarization distribution and the uniform distribution associated with completely unpolarized light. We study the relation between two- and three-dimensional polarization by considering field states with a component in the vacuum state. We apply this formalism to some relevant field states.

Simultaneous monitoring of both optical signal-to-noise ratio and polarization-mode dispersion using polarization scrambling and polarization beam splitting

Abstract: This paper proposes a simple method to monitor both optical signal-to-noise ratio (OSNR) and polarization-mode dispersion (PMD) simultaneously using a polarization-scrambling module followed by polarization beam splitting. OSNR and PMD are obtained from interaction terms between two orthogonal polarization arms. Monitored OSNR and PMD are independent of each other. Experimental results are demonstrated in a 10-Gb/s nonreturn-to-zero (NRZ) system with OSNR from 18 to 36 dB and PMD from 0 to 70 ps.