Relevant bibliographies by topics / Polarisation

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Polarisation'

Author: Grafiati
Published: 4 June 2021
Last updated: 6 July 2024

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Journal articles on the topic "Polarisation"

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Gusarov, Andrei, Perry Beaumont, and Paula Siren. "Performance Enhancement of the Polarimetric Fibre Optical Current Sensor at JET Using Polarisation Optimisation." Sensors 24, no. 2 (January 16, 2024): 555. http://dx.doi.org/10.3390/s24020555.

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To achieve optimal operation of the polarimetry-based FOCS, the light polarisation state at the input of the sensing fibre part must be close to a linear one. In the case of a FOCS deployed on a tokamak, the Joint European Torus (JET) in the present work, the long fibre optics link between the laser source and the sensing fibre modifies the polarisation in an unpredictable way, making it unclear which source polarisation state is to be set. A method for performing the necessary polarisation adjustment in a systematic way is proposed based on the FOCS analysis. The method requires performing data acquisition at two different input polarisations. Based on these measurements, the optimal laser source polarisation can be found. The method was experimentally verified using laboratory set-up and then successfully demonstrated with the FOCS installed at JET.
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Bogdanov, S. A., O. S. Sidelnikov, and A. A. Redyuk. "Application of complex fully connected neural networks to compensate for nonlinearity in fibre-optic communication lines with polarisation division multiplexing." Quantum Electronics 51, no. 12 (December 1, 2021): 1076–80. http://dx.doi.org/10.1070/qel17656.

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Abstract A scheme is proposed to compensate for nonlinear distortions in extended fibre-optic communication lines with polarisation division multiplexing, based on fully connected neural networks with complex-valued arithmetic. The activation function of the developed scheme makes it possible to take into account the nonlinear interaction of signals from different polarisation components. This scheme is compared with a linear one and a neural network that processes signals of different polarisations independently, and the superiority of the proposed neural network architecture is demonstrated.
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O'Brien, D. M., I. N. Polonsky, and J. B. Kumer. "Sensitivity of remotely sensed trace gas concentrations to polarisation." Atmospheric Measurement Techniques 8, no. 11 (November 23, 2015): 4917–30. http://dx.doi.org/10.5194/amt-8-4917-2015.

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Abstract. Current and proposed space missions estimate column-averaged concentrations of trace gases (CO2, CH4 and CO) from high resolution spectra of reflected sunlight in absorption bands of the gases. The radiance leaving the top of the atmosphere is partially polarised by both reflection at the surface and scattering within the atmosphere. Generally, the polarisation state is unknown and could degrade the accuracy of the concentration measurements. The sensitivity to polarisation is modelled for the proposed geoCARB instrument, which will include neither polarisers nor polarisation scramblers to select particular polarisation states from the incident radiation. The radiometric and polarimetric calibrations proposed for geoCARB are outlined, and a model is developed for the polarisation properties of the geoCARB spectrographs. This model depends principally upon the efficiencies of the gratings to polarisations parallel and perpendicular to the rulings of the gratings. Next, an ensemble of polarised spectra is simulated for geoCARB observing targets in India, China and Australia from geostationary orbit at longitude 110° E. The spectra are analysed to recover the trace gas concentrations in two modes, the first denied access to the polarimetric calibration and the second with access. The retrieved concentrations using the calibration data are almost identical to those that would be obtained with polarisation scramblers, while the retrievals without calibration data contain outliers that do not meet the accuracies demanded by the mission.
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O'Brien, D. M., I. N. Polonsky, and J. B. Kumer. "Sensitivity of remotely-sensed trace gas concentrations to polarisation." Atmospheric Measurement Techniques Discussions 8, no. 8 (August 24, 2015): 8779–816. http://dx.doi.org/10.5194/amtd-8-8779-2015.

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Abstract. Current and proposed space missions estimate column-averaged concentrations of trace gases (CO2, CH4 and CO) from high resolution spectra of reflected sunlight in absorption bands of the gases. The radiance leaving the top of the atmosphere is partially polarised by both reflection at the surface and scattering within the atmosphere. Generally the polarisation state is unknown, and could degrade the accuracy of the concentration measurements. The sensitivity to polarisation is modelled for the proposed geoCARB instrument, which will include neither polarisers nor polarisation scramblers to select particular polarisation states from the incident radiation. The radiometric and polarimetric calibrations proposed for geoCARB are outlined, and a model is developed for the polarisation properties of the geoCARB spectrographs. This model depends principally upon the efficiencies of the gratings to polarisations parallel and perpendicular to the rulings of the gratings. Next an ensemble of polarised spectra is simulated for geoCARB observing targets in India, China and Australia from geostationary orbit at longitude 110° E. The spectra are analysed to recover the trace gas concentrations in two modes, the first denied access to the polarimetric calibration and the second with access. The retrieved concentrations using the calibration data are almost identical to those that would be obtained with polarisation scramblers, while the retrievals without calibration data contain outliers that do not meet the accuracies demanded by the mission.
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Piltyay, Stepan, Andrew Bulashenko, Hanna Kushnir, and Oleksandr Bulashenko. "Information Resources Economy in Satellite Systems based on New Microwave Polarizers with Tunable Posts." Path of Science 6, no. 11 (November 30, 2020): 5001–10. http://dx.doi.org/10.22178/pos.64-6.

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One of the fundamental problems of modern digital telecommunications is the economy of digital information and frequency resources, which are highly limited. The introduction of novel telecommunication systems and 5G networks requires searching for principal solutions for the economy and reusing the frequency spectrum. Therefore, modern wireless mobile, terrestrial, and satellite systems use various new technologies to increase communication channels' information capacity for the economy of limited frequency resources. One of the most effective ways to reuse the information system's operating frequency band is to apply antennas with polarisation signal processing. Such systems provide the possibility to transmit and to receive simultaneously signals with different types of polarisation. Consequently, the application of electromagnetic waves with two orthogonal polarisations improves wireless systems' information characteristics for various purposes. This allows doubling the information capacity of mobile, terrestrial, and satellite communication channels. Also, polarisation processing is carried out in meteorological and radar systems to receive, transmit, and process information. The essential elements of such systems are microwave polarisers and orthomode transducers. The electromagnetic characteristics of these devices affect the aspects of the whole system significantly. Main electromagnetic factors include phase, matching, and polarisation parameters. The article presents the development of a compact tunable polarizer based on a square waveguide with three posts. The developed polariser operates in the X-band from 8.0 GHz to 8.5 GHz. Created a mathematical model of the polariser is based on the scattering and transmission matrices. To verify the developed theoretical model's correctness, the calculation of all characteristics was also performed numerically using the finite integration technique. The developed compact polariser based on a square waveguide with three posts allows tuning it's matching and polarisation characteristics by changing all posts' heights. The developed polariser's main advantages are small dimensions, tuning options, and aspects of polarisation transformation.
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Prabhu, A., A. Brandenburg, M. J. Käpylä, and A. Lagg. "Helicity proxies from linear polarisation of solar active regions." Astronomy & Astrophysics 641 (September 2020): A46. http://dx.doi.org/10.1051/0004-6361/202037614.

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Context. The α effect is believed to play a key role in the generation of the solar magnetic field. A fundamental test for its significance in the solar dynamo is to look for magnetic helicity of opposite signs both between the two hemispheres as well as between small and large scales. However, measuring magnetic helicity is compromised by the inability to fully infer the magnetic field vector from observations of solar spectra, caused by what is known as the π ambiguity of spectropolarimetric observations. Aims. We decompose linear polarisation into parity-even and parity-odd E and B polarisations, which are not affected by the π ambiguity. Furthermore, we study whether the correlations of spatial Fourier spectra of B and parity-even quantities such as E or temperature T are a robust proxy for magnetic helicity of solar magnetic fields. Methods. We analysed polarisation measurements of active regions observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics observatory. Theory predicts the magnetic helicity of active regions to have, statistically, opposite signs in the two hemispheres. We then computed the parity-odd EB and TB correlations and tested for a systematic preference of their sign based on the hemisphere of the active regions. Results. We find that: (i) EB and TB correlations are a reliable proxy for magnetic helicity, when computed from linear polarisation measurements away from spectral line cores; and (ii) E polarisation reverses its sign close to the line core. Our analysis reveals that Faraday rotation does not have a significant influence on the computed parity-odd correlations. Conclusions. The EB decomposition of linear polarisation appears to be a good proxy for magnetic helicity independent of the π ambiguity. This allows us to routinely infer magnetic helicity directly from polarisation measurements.
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Eriksson, P., B. Rydberg, and S. A. Buehler. "On cloud ice induced absorption and polarisation effects in microwave limb sounding." Atmospheric Measurement Techniques 4, no. 6 (June 30, 2011): 1305–18. http://dx.doi.org/10.5194/amt-4-1305-2011.

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Abstract. Microwave limb sounding in the presence of ice clouds was studied by detailed simulations, where clouds and other atmospheric variables varied in three dimensions and the full polarisation state was considered. Scattering particles were assumed to be horizontally aligned oblate spheroids with a size distribution parameterized in terms of temperature and ice water content. A general finding was that particle absorption is significant for limb sounding, which is in contrast to the down-looking case, where it is usually insignificant. Another general finding was that single scattering can be assumed for cloud optical paths below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrieval algorithms. The representation of particle sizes during the retrieval is also discussed. Concerning polarisation, specific findings were as follows: Firstly, no significant degree of circular polarisation was found for the considered particle type. Secondly, for the ±45° polarisation components, differences of up to 4 K in brightness temperature were found, but differences were much smaller when single scattering conditions applied. Thirdly, the vertically polarised component has the smallest cloud extinction. An important goal of the study was to derive recommendations for future limb sounding instruments, particularly concerning their polarisation setup. If ice water content is among the retrieval targets (and not just trace gas mixing ratios), then the simulations show that it should be best to observe any of the ±45° and circularly polarised components. These pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations.
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Ferré, Vincent. "Macronisme, polarisation sociale et polarisation politique." Commentaire Numéro169, no. 1 (2020): 215. http://dx.doi.org/10.3917/comm.169.0215.

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Hodgkinson, T. G., R. A. Harmon, and D. W. Smith. "Polarisation-insensitive heterodyne detection using polarisation scrambling." Electronics Letters 23, no. 10 (May 7, 1987): 513–14. http://dx.doi.org/10.1049/el:19870371.

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Heismann, F., P. B. Hansen, S. K. Korotky, G. Raybon, J. J. Veselka, and M. S. Whalen. "Automatic polarisation demultiplexer polarisation-multiplexed transmission systems." Electronics Letters 29, no. 22 (1993): 1965. http://dx.doi.org/10.1049/el:19931308.

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Dissertations / Theses on the topic "Polarisation"

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García, Reyes María Elena. "Income polarisation." Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420261.

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Bregenzer, Josef Johann. "Integrated polarisation rotators." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1573/.

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The ability to control and manipulate the state of polarisation of optical signals is becoming an increasingly desirable feature in numerous applications including integrated optical circuits, semiconductor optical amplifiers (SOAs) and optical communication systems. This thesis introduces the design, optimisation, fabrication and operation of two novel integrated reciprocal single-section passive polarisation converter devices based upon mode-beating. The converter designs consist of asymmetric profiled waveguides, which were realised in a single reactive ion dry-etch process step. An in-situ custom built sample holder was utilised to place the samples at a predetermined angle to the incoming ions, which resulted in waveguide profiles with sloped sidewalls. This fabrication technique also allowed the incorporation of adiabatic taper sections within the device design. The converter section waveguide profile of the first design consists of two sloped sidewalls. Devices realised on a GaAs/AlGaAs material structure achieved a converted transverse magnetic (TM) polarisation purity of 81.4% at a device length of 30 μm for a transverse electric (TE) polarised input signal at an operating wavelength of λ = 1064 nm. The convention used is that TE refers to light polarised in the plane of the wafer and TM refers to light polarised perpendicular to the plane of the wafer. The total optical loss imposed by this device was evaluated to be 1.72 dB. This design was also used for the monolithic integration of a passive polarisation converter incorporated within a Fabry-Perot semiconductor laser diode on an unstrained GaAs/AlGaAs double quantum well heterostructure material system. A predominantly TM polarised optical output from the converter facet of greater than 80% is demonstrated for a converter length of 20 μm at an emitting wavelength of 867.1 nm. The about 1.4 mm long fabricated device has a current threshold level of 100 mA and a side mode suppression ratio (SMSR) of 25 dB. The second converter design is based on the modification of an already existing stripe waveguide structure. The converter section is defined by applying the above mentioned angled dry-etch process on a certain length of the stripe waveguide. The fabricated asymmetric waveguide core profile consists of a sloped undercut. A TM polarisation purity of 90% at a device length of 55 μm for a TE polarised input signal at an operating wavelength of λ = 1064 nm was achieved at the output. The total optical loss imposed by this device was evaluated to be 0.47 dB.
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Pérez, Linde Angel Joaquin. "Application of cross polarisation techniques to dynamic nuclear polarisation dissolution experiments." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11417/.

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Dynamic Nuclear Polarisation (DNP) was suggested for the first time by Albert Overhauser in early 1950s. In DNP experiments the polarisation from electrons can be transferred to nuclei by irradiation of the electron resonance line. There are several possible mechanisms for polarisation transfer that involve DNP in solid state depending on the width of the electron line in respect to the nuclear Larmor frequency. In this thesis, the efficiency of TEMPO radical (2,2,6,6 tetramethilpiperidine, 1 oxyl) for DNP is demonstrated in combination with nuclear polarisation transfer techniques for dissolution experiments. New cryo-probes were developed for DNP and cross polarisation (CP) for operation temperatures as low as 1.5 K. Two of them were designed for dissolution experiments. Some published sequences of nuclear polarisation transfer were tested at low temperatures and compared. Novel sequences were implemented for efficient CP in organic samples doped with TEMPO to allow for a consecutive dissolution experiment. The combination of DNP with new CP sequences at low temperatures, achieved at least twice the 13C polarisation obtained with DNP and in a substantially shorter time (between 5 to 10 minutes) in samples doped with TEMPO. The polarisation levels obtained in samples of [13C-1] labelled Na acetate in a few minutes was comparable to the polarisation obtained with trityl radicals in a few hours. In addition, another strategy was investigated by using brute force polarisation as a mechanism for achieving large levels of nuclear spin order. The problem presented by this method is the long relaxation time required to obtain the thermal equilibrium polarisation. By doping with lanthanides samples of [13C-1] labelled Na acetate in 1:1 glycerol-water, it was possible to obtain thermal equilibrium for a 13C spin system in less than one hour.
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Böcker, Matthias. "Messung der transversalen L-Polarisation [Lambda-Polarisation] mit dem HERA-B-Detektor." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971196591.

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Gul-E-Saman. "Surface analysis using polarisation." Thesis, University of York, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583351.

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Unpolarised light incident on a surface acquires partial polarisation due to the orientation of the dipoles in the scatterer. This thesis focuses on the use of polarised light for diffuse reflectance for surface analysis. Since, the state of polarisation is acquired on interaction with the surface, the polarised light contains information about the surface properties (of the scatterer). A great amount of research has been carried out in computer vision for surface analysis using image analysis techniques. Recently, the trend has been to combine optical techniques with computer vision in order to arrive at better analysis techniques by methods that analyse the intrinsic qualities of the surfaces under study. An overview of the recent work that has been carried out in the field is given in Chapter 2 in context to this thesis. The contributions of this thesis are: 1. the robust computation of polarisation image using M-estimators, the smoothing of phase of polarisation by using directional statistics and using the calculated parameters for effective surface recovery, 2. estimation of the refractive index of a diverse set of surfaces of known and unknown refractive indices and using the estimates for segmentation, 3. estimating the complex refractive index which incorporates the phenomenon of absorption by two methods existing in literature, using a. ellipsometry and b. multiple polarisation measurements while building up on the case of surface analysis being related to its optical properties and 4. carrying out a preliminary study by modifying the geometric factor of the polarimetric bidirectional reflectance distribution function. Experimental evidence has been presented in the thesis for the methods that have been used for a variety of objects with varying geometrical and surface properties. The approach in this thesis has been to adopt simple and adaptable techniques that can be easily employed without the use of sophisticated equipment.
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Thompson, P. G. "Polarisation-tunable plasmonic devices." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1396243/.

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This research project aims to investigate the phenomenon of extraordinary optical transmission (EOT) in arrays of asymmetric cruciform apertures. The specific area of EOT examined is the dependence of transmission on incident polarisation. The approach to investigating this phenomenon can be divided into three main sections: fabrication, characterisation and simulations. The method of fabrication involved two main processes: fabrication of Au thin films on CaF2 substrates using thermal evaporation, and the milling of cruciform apertures in the thin films using focused in beam (FIB). A 5 nm adhesion layer of Cr was first thermally evaporated onto the CaF2 substrate followed by an Au film, typically of 30 nm thickness. The unit cells have a lattice constant of 2 μm and typical feature sizes of the apertures are between 160 nm and 1675 nm. The transmission and reflection characteristics are examined using Fourier transform infrared spectroscopy (FTIR) for the Mid IR wavelength range. The dependence of the transmission and reflection on polarisation was investigated. It was found that the arrays display two distinct transmission maxima and a point at which transmission is invariant for all polarisations. The transmission peaks occurred in the wavelength range of 2μm to 6 μm. An ensemble of arrays was fabricated to examine the change in wavelength of the transmission peaks and the invariant point as one of the aperture dimensions was varied. It was found that the transmission wavelength and the wavelength of the invariant point could be tuned by altering the dimensions of the cruciform apertures. Simulations for transmission and reflection were carried out in addition to field profile simulations. Together, these confirmed the assumed processes by which the polarisation dependent transmission maxima were generated, i.e. by localised surface plasmons. One of the arrays more closely examined had transmission peaks at 3.9μm and 5.75μm and an invariant point at 4.46μm. For this array simulations were also used to determine the polarisation state of the transmitted wave. The simulations show that arrays of asymmetric apertures change the incident polarisation such that the transmitted wave becomes elliptically polarised with a major axis that is in general different from the polarisation angle of the incident wave. A maximum shift of around 33! was determined using simulations for a wavelength ! = 3.9μm and an incident polarisation of 60! relative to the x axis. Experimental data was obtained that corroborates these findings.
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Watley, Daniel Andrew. "Polarisation mode dispersion compensation." Thesis, University of Cambridge, 2000. https://www.repository.cam.ac.uk/handle/1810/272331.

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Siddiqui, Z. S. "Fast polarisation sampling system for characterisation of polarisation noise in fibre transmission systems." Thesis, University of Essex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303462.

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Prunet, Simon. "Polarisation du ciel micro-ondes." Phd thesis, Université Paris Sud - Paris XI, 1998. http://tel.archives-ouvertes.fr/tel-00008317.

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La mission ESA Planck offre une opportunité sans précédent de mesurer de manière très précise la polarisation de l'émission Galactique et extragalactique dans le domaine millimétrique et sub-milli\-métrique ; elle devrait notamment permettre de mesurer la polarisation du Fond Cosmique Micro-ondes (FCM). Dans le premier chapitre, nous expliquons brièvement l'intérêt scientifique d'une telle mesure, et revoyons les technologies instrumentales qui la permettent. Dans le second chapitre, nous modélisons les caractéristiques statistiques de l'émission galactique polarisée, en particulier celle des poussières (plus particulièrement importante pour l'instrument haute fréquence -HFI- de Planck). Dans le troisième chapitre, nous présentons une méthode de filtrage multi-fréquence permettant la séparation des différentes composantes astrophysiques de l'émission millimétrique et sub-millimétrique, et permettant de quantifier les erreurs de la mesure des propriétés statistiques (spectre de puissance) de ces différents processus, en particulier le FCM. Dans le quatrième chapitre, nous estimons l'erreur commise sur la mesure des paramètres cosmologiques, conséquence des erreurs estimées au chapitre précédent. Dans un cinquième chapitre, nous estimons la contribution aux anisotropies du FCM de l'effet de lentille gravitationnelle en mouvement, causé par une population d'amas et de groupes de galaxies. Enfin, dans un sixième chapitre, nous présentons un modèle semi-analytique simple de formation de galaxies, où le taux de formation d'étoiles est controlé par la température du milieu intergalactique.
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Campbell, Ewen K. "Atomic polarisation in molecular photodissociation." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:d1fd3e32-62be-4154-880f-431ec6045baa.

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1) species show a preference for the MJ = ±1 sub-levels. For these bands the electronic alignment is very similar to that observed in the dissociation of OCS, indicating a similar mechanism, at least in the exit channel, is responsible for the polarisation in both systems.
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Books on the topic "Polarisation"

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Board, Securities and Investments. Polarisation. [London]: Securities and Investments Board, 1991.

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Berglund, Tomas, and Ylva Ulfsdotter Eriksson. Scrutinising Polarisation. London: Routledge, 2024. http://dx.doi.org/10.4324/9781003412861.

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Polarized electrons. 2nd ed. Berlin: Springer-Verlag, 1985.

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Huard, Serge. Polarisation of light. New York: John Wiley, 1997.

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Linda, Hantrais, Mangen Stephen P, and Cross-National Research Group, eds. Polarisation and urban space. Loughborough: Cross-National Research Group, 1994.

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P, Mangen Stephen, Hantrais Linda, and Cross-National Research Group, eds. Polarisation and urban space. Leicestershire: Cross-National Research Group, 1993.

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Authority, Financial Services. Reforming Polarisation: First Steps. London: Financial Services Authority, 2001.

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Willmott, Peter. Polarisation and social housing. London: Policy Studies Institute, 1988.

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Torcal, Mariano. Affective Polarisation in Spain. London: Routledge, 2023. http://dx.doi.org/10.4324/9781003398332.

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McIntyre-Mills, Janet J., and Yvonne Corcoran-Nantes, eds. From Polarisation to Multispecies Relationships. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6884-2.

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Book chapters on the topic "Polarisation"

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Wiesel, Ilan. "Polarisation." In Power, Glamour and Angst, 1–46. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1367-7_1.

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Beynon, J. "Polarisation." In Work Out Waves and Optics, 117–50. London: Macmillan Education UK, 1988. http://dx.doi.org/10.1007/978-1-349-10165-8_5.

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Eichler, Jürgen, and Hans Joachim Eichler. "Polarisation." In Laser, 291–98. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-41438-1_15.

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Eichler, Jürgen, and Hans-Joachim Eichler. "Polarisation." In Laser in Technik und Forschung, 257–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-662-42591-6_15.

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Douglas, Roy. "Polarisation." In World Crisis and British Decline, 1929–56, 58–70. London: Palgrave Macmillan UK, 1986. http://dx.doi.org/10.1007/978-1-349-18194-0_5.

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Eichler, Jürgen, and Hans Joachim Eichler. "Polarisation." In Laser, 275–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-08243-0_15.

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Eichler, Jürgen, and Hans Joachim Eichler. "Polarisation." In Laser, 271–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-08245-4_15.

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Eichler, Jürgen, and Hans Joachim Eichler. "Polarisation." In Laser in Technik und Forschung, 263–70. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-662-08247-8_15.

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Eichler, Jürgen, and Hans-Joachim Eichler. "Polarisation." In Laser in Technik und Forschung, 257–65. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-662-22080-1_15.

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Crawford, Frank S. "Polarisation." In Schwingungen und Wellen, 225–58. Wiesbaden: Vieweg+Teubner Verlag, 1989. http://dx.doi.org/10.1007/978-3-322-90777-6_8.

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Conference papers on the topic "Polarisation"

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Hutchings, D. C., J. S. Aitchison, B. S. Wherrett, G. T. Kennedy, and W. Sibbett. "Polarisation dependence of ultrafast nonlinear refraction in semiconductor waveguides." In Nonlinear Guided Waves and Their Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/nlgw.1995.nsab10.

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There is considerable interest in the optical Kerr effect, described by the nonlinear refractive index n2, as it can be employed to perform high-speed, all-optical switching. Semiconductor waveguides offer an attractive media for compact, integrated all-optical switching.1,2 The dispersion of n2 in direct-gap, zinc- blende semiconductors was recently accurately calculated using a four-band Kane model.3 In this paper the polarisation dependence of nonlinear refraction in zinc-blende semiconductors will be addressed. This dependence has two aspects to it: (1) an optical polarisation dependence which provides a variation in n2 for linear and circular polarisations.4 This variation can occur even for isotropic media. The same dependence also gives a different value for the cross-phase-modulation using parallel and perpendicular polarisations (orthogonal cross-phase-modulation was employed in a demonstration of all-optical demultiplexing5). (2) a material polarisation dependence which provides a variation in n2 depending on how the optical polarisation is orientated with respect to the crystalline axes.
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2

Varming, P., J. L. Philipsen, M. O. Berendt, V. C. Lauridsen, J. H. Povlsen, J. Hübner, M. Kristensen, and B. Pálsdóttir. "Polarisation control mechanism of DFB fibre lasers." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.ctuf7.

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Since the introduction of single-mode DFB fibre lasers with UV induced phase-shift, these lasers have found many applications within optical communication [1]. Single polarisation operation of the laser could be attributed to a polarisation dependence of either the grating reflectivity, background loss, erbium gain, or the phase-shift. It has been shown that a birefringent distributed phase-shift causes a considerable difference in the magnitude of the phase-shift experienced by the two polarisations [2]. However, until now it has not been clarified which polarisation dependent effect is dominating in obtaining single polarisation operation. In this paper, we present experimental evidence that a birefringent distributed phase-shift is the dominating effect.
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3

Yamashita, Shinji, and Gregory J. Cowie. "Single-polarisation operation of injection locked fibre DFB lasers." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.ctuf6.

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Optical fibre distributed-feedback (DFB) lasers using UV-written fibre Bragg gratings on Er3+:Yb3+ fibres feature single-frequency operation, thus are a promising technology for applications in optical fibre communications[1]. Most fibre DFB lasers, however, actually operate in two orthogonal polarisations as a result of polarisation independence in the fibre DFB resonator, which is not desirable for these applications. In this paper, we report single-polarisation operations of fibre DFB lasers using injection locking techniques, which are similar to those used for polarisation switching in He-Ne lasers[2].
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4

Snelling, M. J., P. Perozzo, R. Bambha, A. Miller, and D. C. Hutchings. "Time Resolved Optical Orientation Used to Examine Coulomb Screening and Phase Space Filling in Quantum Well Excitonic Saturation." In Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/qo.1993.qthc.2.

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Picosecond pulses from a mode locked dye laser were used in an excite-probe configuration (figure 1) with excite and probe beam powers of 200uW and 20uW respectively. Both beams were polarised to produce either mutually orthogonal linear polarisations (linear-linear), the same circular polarisation (same-circular), or opposite circular polarisation (opposite-circular). The sample was fabricated by MBE with a p-type background doping of 1016cm-3, etched to remove the GaAs substrate, and consisted of 120 periods of 65Å quantum wells with 212Å AI0.4Ga0.6As barriers.
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5

HODGKINSON, T. G., R. A. HARMON, and D. W. SMITH. "POLARISATION INSENSITIVE HETERODYNE DETECTION USING POLARISATION SCRAMBLING." In Optical Fiber Communication Conference. Washington, D.C.: OSA, 1987. http://dx.doi.org/10.1364/ofc.1987.pdp15.

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6

Goddard, J. W. F. "Polarisation observations of an intense squall line." In IEE Colloquium on Polarisation in Radar. IEE, 1996. http://dx.doi.org/10.1049/ic:19960439.

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7

Gontijo, I., D. T. Neilson, A. C. Walker, G. T. Kennedy, and W. Sibbett. "Nonlinear single wavelength polarisation switching in InP-based waveguides." In Nonlinear Guided Waves and Their Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/nlgw.1995.nsac1.

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All-optical switches have attracted much attention due to their potential application in high speed optical communication systems. Among the many concepts that have been studied are pump/probe nonlinear etalon devices, both in InGaAs/InP1 in the wavelength range of 1.5μm and in GaAs-based structures2at 0.85μm. In general, the excite (pump) and probe wavelengths have to be different, to avoid probe absorption. The use of a single wavelength but different states of polarisation in the pump and probe beams to produce switching has been investigated in CdS.3 In this case, the device relies on the natural dichroism of a CdS crystal platelet, to absorb only light of a specific polarisation, which is chosen to be the pump. InGaAs/InP quantum wells exhibit much larger dichroism for TE/TM polarisations and we have observed large refractive index changes at wavelengths away from the bandedge.4 Reported below are experiments where a single wavelength was used, together with the large splitting between the heavy and light hole absorption bandedges in InGaAs/InP quantum well waveguides, to demonstrate a two- polarisation switch with signal gain. The waveguide, with uncoated facets, is a nonlinear Fabry-Perot etalon, whose refractive index can be changed by the absorption of the pump beam which in turn changes the cavity transmission characteristics sensed by the probe beam. This type of device could have important applications, as it uses a single wavelength and offers cascadability and compatibility of all-optical switching with optical fibre communications.
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8

Watts, S. "Optimum radar polarisation for target detection in sea clutter." In IEE Colloquium on Polarisation in Radar. IEE, 1996. http://dx.doi.org/10.1049/ic:19960435.

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9

Blacknell, D. "Single point and spatial statistics of polarimetric SAR imagery." In IEE Colloquium on Polarisation in Radar. IEE, 1996. http://dx.doi.org/10.1049/ic:19960432.

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10

Britton, A. "Polarimetric scattering properties of natural targets at 80 GHz." In IEE Colloquium on Polarisation in Radar. IEE, 1996. http://dx.doi.org/10.1049/ic:19960433.

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Reports on the topic "Polarisation"

1

Hamilton, David Jonathan. Polarisation Transfer in Proton Compton Scattering at High Momentum Transfer. Office of Scientific and Technical Information (OSTI), January 2004. http://dx.doi.org/10.2172/917711.

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2

Rowson, Peter C. Positron Polarisation and Low Energy Running at a Linear Collider. Office of Scientific and Technical Information (OSTI), January 2002. http://dx.doi.org/10.2172/798967.

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3

Jelka Stojanov, Jelka Stojanov. Actual and perceived polarisation in people’s opinions on behavioural policy interventions. Experiment, June 2022. http://dx.doi.org/10.18258/27553.

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4

Toner, W. T. Resonance method to produce a polarisation asymmetry in electron-positron storage rings. Office of Scientific and Technical Information (OSTI), January 1988. http://dx.doi.org/10.2172/7126893.

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5

Liedhegener, Antonius, Gert Pickel, Anastas Odermatt, Alexander Yendell, and Yvonne Jaeckel. Polarisation and social cohesion: the ambivalent potential of religion in democratic societies. Leipzig University, March 2021. http://dx.doi.org/10.36730/rtv.2020.

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6

Zhang, Lin. High Extinction Ratio In-Fibre Polarisers by Exploiting Tilted Fibre Bragg Grating Structures for Single-Polarisation High-Power Fibre Lasers and Amplifiers. Fort Belvoir, VA: Defense Technical Information Center, November 2009. http://dx.doi.org/10.21236/ada524631.

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7

Fluzin, Cyprien. The Use of Administrative Measures Against an Evolving Terrorist Threat: Raising the Stakes for Human Rights, the Rule of Law, and Democracy. ICCT, March 2024. http://dx.doi.org/10.19165/2024.1412.

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Terrorism in Western nations has changed significantly over the past years, putting security services to the test and prompting necessary adaptations in counter-terrorism strategies. In this context, states may be tempted to resort to more flexible and swiftly implemented tools such as administrative measures. However, this Policy Brief argues that the known risks associated with administrative measures may be magnified today by a combination of factors and pose new challenges. First, the broadening of the perceived terrorist threat, as it coincides with escalating social and political tensions in many democracies, contributes to obscuring the boundaries between activism, disorder, extremism (violent or not), and terrorism, increasing the risk of misuse as part of attempts to protect the public order. Second, the increasingly tense political climate displaying growing polarisation and escalating populist rhetoric raises additional risks of intentional abuse. Finally, it appears that the overreliance on administrative measures, even when prima facie compliant with the law, may also contribute to an erosion of some human rights and rule of law principles. In addition to causing harm to specific individuals or groups, the accumulation of these circumstances may also affect entire societies and undermine democracy altogether. This Policy Brief argues that the current backdrop calls for renewed caution in the use of administrative measures and a dramatic strengthening of existing safeguards and protections against arbitrary or unlawful uses.
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8

Potts, Tavis, Paul Dargie, Maren Mitchell, Daria Shapovalova, and John Bone. Climate Assemblies and Deliberative Democracy: A Global Best Practice Review. University of Aberdeen, 2024. http://dx.doi.org/10.57064/2164/23210.

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With climate change policies increasingly used as a tool for further political polarisation, it is important to explore tools that could help bring the public on board with climate ambition. Climate assemblies, if done to a high standard, can increase community empowerment while rebuilding legitimacy within policy-making from the view of the general public. Whilst climate assemblies are important it is also vital to research theoretical approaches as well as real-world experience of climate assemblies to develop better understanding of how assembly outputs can effectively develop and legitimise climate policy and support participatory democracy. This report is developed by the Just Transition Lab at the University of Aberdeen. It is part of the Just Transition Communities Project led by North East Scotland Climate Action Network Hub and funded by the Scottish Government Just Transition Fund. The project plans to explore how communities in the North East Scotland can be involved in and drive the process of designing, creating, and delivering a just transition. This report aims to inform future climate assemblies initiatives, leading to increased community participation in climate change mitigation and adaptation policy. This report provides a literature review as an introduction to deliberative democracy and climate assemblies. It examines theory and practice in all the relevant aspects of using climate assemblies to increase public awareness of climate change, aid climate policy-making, and increasing the legitimacy and public acceptance of current and future policies. From the design of climate assemblies to participant recruitment, scale, and outcomes – this report provides an overview of theoretical approaches and 14 case studies of climate assemblies to present a rounded view of deliberative democracy in practice.
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O’Reilly, Jacqueline, and Rachel Verdin. Measuring the size, characteristics and consequences of digital work. Digital Futures at Work Research Centre, February 2022. http://dx.doi.org/10.20919/whfq8202.

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This working paper provides a summary assessment of the existing literature and data on digital forms of employment internationally. It illustrates the variability in how it is defined, how it is growing and what kind of risks are associated with these developments. Evaluation of these types of jobs is divided. On one hand, optimists point to the attractions and relative ease in finding employment on digital platforms; on the other hand, more critical perspectives argue that these employment contracts can result in exclusion from social protection systems. The evidence indicates that while overall a relatively small proportion of all employment digital work is growing, both on platforms as well as adoption amongst more traditional companies. The characteristics of digital workers can vary by region and occupation. Overall, they tend to be predominantly younger and more likely male, with a growing number of women albeit in particular occupations. Skills and earnings levels vary but the key issues of disputes is around pay, conditions and employment status. The consequences of this form of work for those with lower skilled digital employment can undermine their social citizenship: they lack comparable employment rights, or when unemployed entitlement to adequate social protection. The potential polarisation effects of digital exclusion and deficits will severely hamper the wider benefits of transparency offered by these technologies. During the pandemic these trends have become more apparent. The imbalance of bargaining power and regulatory governance to bridge gaps in citizenship entitlements undermines the collective potential of policy makers and trade unions to address these challenges. Nevertheless, there is emerging evidence of innovative challenges and contestation of these gaps by both union organisations and national regulators attempts to adapt social protection
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Toivonen, Tuuli, Aina Brias Guinart, Johanna Eklund, Hästbacka Matti, Leppämäki Tatu, and Torkko Jussi. Potential of mobile big data for visitor monitoring : Report of the MOBICON workshop held in Helsinki 28.9.2023. Digital Geography Lab, University of Helsinki, 2023. http://dx.doi.org/10.31885/2024.030501.

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The Changes in Nature Visitation and the Potential of Mobile Big Data for Visitor Monitoring workshop was held in Helsinki on 28.9.2023. We organized the workshop as part of the five-year MOBICON research project (Mobile Big Data for Understanding People in Nature - Detecting short- and long-term changes and their implications for biodiversity conservation) funded by Kone Foundation. The aim of the workshop was to collect expert opinions related to the changes in the recreational use of nature, the monitoring needs related to the changing visitations, and to discuss the possibilities of various new data sources to meet managerial information needs. Eight experts from different organisations (Metsähallitus, City of Helsinki, Uusimaa Recreation Area Association Uuvi and Suomen Latu r.y.) participated in the event. Prior to the workshop, the participants had answered a survey about their experiences and information needs related to the changing visitations. The discussion progressed from the results of the survey to more in-depth discussions. Below we summarize the key results from the discussions. The recreational use of nature was seen to be changing. Recreational use is increasing and its temporal rhythms are changing. At the same time, the visitor base becomes more diverse because of the general diversification of society and the fact that new user-groups have started to explore nature. Activities and ways of being in nature are also diversifying. Approaching the changes through four megatrends (social, environmental, political and technological changes). The social and environmental drivers of change were seen as the most important. social changes were identified to be related to the ageing of the population and the diversification of nature visitors. Climate change, as an environmental factor, was identified as the most important driver of change, impacting both nature but also human behaviour. Among the political drivers of change, particularly the increasing polarisation of society emerged in the discussion. In addition, political decisions relating to everyone's rights, biodiversity protection and resources directed for the management of recreational areas were seen as important. Technological changes were identified as important and this change taking place as part of the broader technologization of society. On the one hand, this general technologization increases the opportunities for access to and sharing of information. On the other hand, the increased ‘measurement culture’ also affects the amounts of recreational use, as people are aiming to reach their kilometer or step targets. The information needs of organisations were recognized to include 1) planning of management actions, 2) justifying one's own activities for securing funding and 3) informing visitors. Information is needed on visitor flows and their spatial and temporal distribution. In addition, information about the visitors themselves was considered necessary, especially as the visitor base is becoming more diverse. The workshop participants also expressed concern about those who do not visit recreational areas: how get more information about them and the factors that limit nature visits. Collecting visitor data was seen as expensive and time-consuming, which is why finding new kinds of data sources has potential. Mobile data was evaluated as an interesting source of information and its various aspects were discussed through a SWOT analysis. However, it was clear that in operational use, information must be reliable and easily accessible and some doubts were raised on the potential of mobile big data from this aspect. The event was organised by Aina Brias Guinart, Matti Hästbacka, Tatu Leppämäki, Jussi Torkko and Tuuli Toivonen. Johanna Eklund participated in the workshop from maternity leave. More information about the event or research can be found on the project's website or by e-mail to the project's researchers: mobicon-project@helsinki.fi. The MOBICON project will operate from 2022 to 2026 and it is funded by Kone Foundation. Website: https://www.helsinki.fi/en/researchgroups/digital-geography-lab/projects/mobicon.
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