Showing papers on "Polarization rotator published in 1985"
TL;DR: In this article, a comparison of experimental imaging results obtained with linearly polarized and circularly polarized radiofrequency excitation and reception is presented, and the expected benefits of circular polarization over linear polarization in reduction of excitation power (up to 50% reduction) and signal-to-noise advantage (√ 2) have been realized in practice with cylindrical objects and human subjects.
271 citations
TL;DR: In this paper, a new apparatus for in vivo retinal-scattering experiments incorporating Mueller-matrix ellipsometry is described, where the state of polarization of the entrance beam is modulated, after which the Stokes vector of the exit beam is assessed.
Abstract: A new apparatus for in vivo retinal-scattering experiments incorporating Mueller-matrix ellipsometry is described. The basic principle is that the state of polarization of the entrance beam is modulated, after which the Stokes vector of the exit beam is assessed. Results show that nearly 90% of the degree of polarization of the entrance beam is preserved after double passage of the ocular media and retinal scattering. Changes in the state of polarization are studied in terms of a rotation around an eigenvector on the Poincare sphere. These studies show that the type of change in the state of polarization of the totally polarized component is probably caused by a linearly birefringent process.
74 citations
TL;DR: It is shown experimentally that the role played by the detector optical feedback can be varied in a controlled manner in order to obtain abrupt switches between two perpendicular polarization states.
Abstract: The light of a quasi-isotropic, single-mode gas laser is linearly polarized for a line ${J}_{a}=1\ensuremath{\rightarrow}{J}_{b}=2$. However, the azimuth of polarization can vary inside the line. Among the many different effects which cause these variations, we describe the role played by the detector optical feedback. We show experimentally that its amplitude and phase can be varied in a controlled manner in order to obtain abrupt switches between two perpendicular polarization states. Polarization bistability and hysteresis effects can then be commanded and studied from the outside of the laser.
39 citations
TL;DR: In this article, a binary ferroelectric liquid-crystal mixture with room-temperature Ferroelectricity and a large spontaneous polarization has been developed and a guest-host-type device was fabricated using the mixture, and some potential problems in the application of the materials to electro-optical switching devices are pointed out on the basis of the optical properties of this device.
Abstract: A binary ferroelectric liquid-crystal mixture having both room-temperature ferroelectricity and a large spontaneous polarization has been developed. The temperature range is from 20°C to 34°C. The spontaneous polarization is almost the same value, 4 nC/cm2, as that in DOBAMBC. Five material constants for the mixture; the transition temperature, spontaneous polarization, helical pitch, tilt angle and birefringence, are reported. A guest-host-type device was fabricated using the mixture, and some potential problems in the application of the materials to electro-optical switching devices are pointed out on the basis of the optical properties of this device.
36 citations
Patent•
15 Jul 1985TL;DR: In this paper, a control means permitting to set arbitrarily the polarization angle of the polarizer and that of the analyzer is provided, so that the degree of fluorescence polarization is obtained by using a plurality of the polarization angles and the fluorescence intensities corresponding thereto.
Abstract: This invention relates to a device for measuring fluorescence polarization, which permits to measure the degree of fluorescence polarization in a short time and also its variations in time. In order to achieve this object, a device for measuring fluorescence polarization according to this invention is provided with a control means permitting to set arbitrarily the polarization angle of the polarizer and that of the analyzer, by means of which the polarization angle of the polarizer or the analyzer is successively varied to arbitrary values so as to obtain polarization angles and fluorescence intensities corresponding thereto so that the degree of fluorescence polarization is obtained by using a plurality of the polarization angles and the fluorescence intensities corresponding thereto.
30 citations
TL;DR: In this article, the authors evaluated the coupling coefficient of a single-mode fiber having an elliptical core with 10 percent ellipticity at wavelengths of 0.85 and 1.3 μm.
Abstract: Polarization mode coupling coefficient is evaluated from the measurement of polarization mode dispersion as a function of fiber length in a single-mode fiber having an elliptical-core with 10-percent ellipticity. The modal dispersion measurement are carried out by the improved spatial technique based on an optical heterodyne detection at the wavelengths of 0.85 and 1.3 μm. The coupling coefficients are evaluated from the measurements to be 3.4 \times 10^{-3} and 4.6 \times 10^{-3} m-1for modal-birefringence magnitudes of 8 \times 10^{-6} and 3 \times 10^{-6} , respectively. The coupling coefficients obtained from the dispersion measurement are coincident with those evaluated from the extinction-ratio measurements. In addition, dependence of the coupling coefficient on propagation constant difference between the two orthogonally polarized HE 11 modes is investigated based on Lorentzian power spectrum model.
22 citations
Patent•
21 Aug 1985TL;DR: In this paper, two quasi-monochromatic radiations with slightly different optical frequencies are generated, and a radiation is converted into a 45° linearly polarized radiation, while the other presents the polarization state imposed by a body under test.
Abstract: Method and device for realtime measurement of the state of polarization at a quasi-monochromatic light beam. Two quasi-monochromatic radiations with slightly different optical frequencies are generated. A radiation is converted into a 45° linearly polarized radiation, while the other presents the polarization state imposed by a body under test. In each radiation, horizontal and vertical polarization components are separated, and then recombined into two different beams comprising radiations at both frequencies, respectively polarized in the same plane. Beatings between the two components of each beam are originated and from the two electrical signals in the radiofrequency range thus obtained the information is extracted on the relative phase and the amplitude of the two components of the radiation with polarization imposed by the body under test.
14 citations
TL;DR: In this article, the authors studied the effect of broad bandwidth of light on cross talk in the mode-coupling parameter by means of the autocorrelation function of the light electric field.
Abstract: Random polarization coupling with a broadband source in birefringent polarization-maintaining fibers is carefully studied. The effect of the broad bandwidth of light on cross talk is formulated in the mode-coupling parameter by means of the autocorrelation function of the light electric field. It is shown that, for light with a Lorentzian-shaped spectrum, cross talk increases as the spectral width becomes larger but is invariant for light with a Gaussian-shaped spectrum.
12 citations
ENEA1
TL;DR: In this article, a superradiant FIR Raman laser was shown to show a spontaneous gain about 1.5 times greater than the linear polarization as expected from the theory when the pump detuning from the resonant line is larger than the Raby frequency.
8 citations
Patent•
05 Nov 1985
TL;DR: A liquid crystal wave division device includes first and second polarization changing cells, which utilize homogeneously aligned nematic liquid crystal material to effect the change of polarization of a preselected frequency portion of a multifrequency incident light beam as mentioned in this paper.
Abstract: A liquid crystal wave division device includes first and second polarization changing cells, the polarization changing cells utilize homogeneously aligned nematic liquid crystal material to effect the change of polarization of a preselected frequency portion of a multifrequency incident light beam.
8 citations
TL;DR: In this paper, the authors investigated whether, in a linearly birefringent step-index single-mode fiber, Maxwell's equations can be solved rigorously by separation of variables.
Abstract: We investigate whether, in a linearly birefringent step-index single-mode fiber, Maxwell's equations can be solved rigorously by separation of variables. If the initial assumptions are the same as in an isotropic fiber, then, although many more steps are needed, the final equations are simple and easy to compare with the isotropic case. It is shown that their solutions are never exactly self-consistent. Consequently, the states of polarization of the transverse fields are sensitive to anisotropy, as it had already been proved experimentally. Furthermore, an isotropic fiber "equivalent" to the anisotropic one for what concerns one individual polarization state can be defined only within an uncertainty range comparable to the birefringence.
TL;DR: In this article, a coupled power model was proposed to investigate the effect of intentional birefringence on the two polarization states of a single-mode optical fiber, which leads to completely analytical results, such as excess attenuation of the desired polarization, finite value of the extinction ratio, and residual polarization dispersion.
Abstract: Intentional birefringence induces an excess loss on one of the two polarization states of a single-mode optical fiber. Yet it may be not sufficient to avoid polarization coupling completely. In this case, we have some undesired effects, such as excess attenuation of the desired polarization as well, finite value of the extinction ratio, and residual polarization dispersion. Such effects are investigated through a coupled power model, which leads to completely analytical results.
TL;DR: The analysis of the local birefringence in single-mode fibers by polarization optical-time-domain reflectometry in the absence of any magneto-optic effect is developed in this paper.
Abstract: The analysis of the local birefringence in single-mode fibers by polarization optical-time-domain reflectometry in the absence of any magneto-optic effect is developed. To this end, group-theoretic relations between the Jones calculus and the Poincare sphere representation are used in developing the theory. Reviews contradicting early research on locally varying birefringence and subsequent theories for the backscattering measurement are made. Although we conclude that the local birefringence cannot be measured in a strict sense by the backscattering method, theoretical investigation shows that a priori information on birefringence characteristics, such as the local fast-axis angle of the general elliptical birefringence, enables us to evaluate the birefringence matrix by measuring the polarization state of the backscattered light. A scheme for finding the Jones matrix by sectioning the length of a single-mode fiber is presented.
Patent•
15 Feb 1985
TL;DR: In this article, a 1/2 wavelength plate is placed between the first and the second polarization planes of the optical fiber 6-b to adjust the direction of an incident light.
Abstract: PURPOSE:To execute a coincidence adjustment of a polarization direction with a high accuracy by placing a 1/2 wavelength plate so as to be rotatable between the first and the second polarization plane maintaining optical fibers. CONSTITUTION:When plugs 7-a, b is inserted into a sleeve 10 of an adaptor, an emitted light of the first polarization plane maintaining optical fiber 6-2 is coupled with the second polarization plane optical fiber 6-b. As for a 1/2 wavelength plate 11, when its optical axis and a linearly polarized light direction of an incident light make an angle theta, a linearly polarized light direction of an emitted light is rotated by 2theta. Therefore, when the linearly polarized light direction from the first polarization plane maintaining optical fiber 6-a does not coincide with a polarization axis of th second polarization plane maintaining optical fiber 6-b, a linearly polarized light maintaining coincided with the polarization axis of the polarization plane maintaining optical fiber 6-b can be coupled with the polarization plane maintaining optical fiber 6-b by rotating a rotary frame 13. In this case, the adjustment can be executed easily by observing the quantity of light and the polarization plane of the emitted light of the other end of the polarization plane maintaining optical fiber 6-b.
TL;DR: In this article, two kinds of effects of the depolarization field in a ferroelectric crystallite of the polymer on its polarization reversal switching are discussed, i.e., the interfacial polarization charge between reversed and unreversed domains increases with increasing fraction of the former, resulting in an acceleration of the polarization reversal of the reversed domain.
Abstract: Two kinds of effects of the depolarization field in a ferroelectric crystallite of the polymer on its polarization reversal switching are discussed. Space charges on the crystallite-amorphous phase interface reduce the depolarization field, decelerating the polarization reversal. In the course of polarization reversal, this interfacial polarization charge between reversed and unreversed domains increases with increasing fraction of the former, resulting in acceleration of the polarization reversal of the unreversed domain.
TL;DR: In this paper, the frequency-dependent polarization of atomic fluorescence excited by broad-band radiation was derived in terms of the contributions to the quasistatic profile from the various interatomic difference potentials.
Abstract: We use detailed-balance considerations to relate the frequency-dependent polarization of atomic fluorescence excited by broad-band radiation to the polarization properties of the collision-induced fluorescence line excited by narrow-band radiation. The polarization of the fluorescence in the first case must display a change when the detected frequency is tuned outside the bandwidth, due to the contribution of Rayleigh scattering. In the special case of adiabatic reorientation followed by emission in the quasistatic wing of the spectral line, we derive explicit expressions for the frequency-dependent polarization in terms of the contributions to the quasistatic profile from the various interatomic difference potentials.
31 Oct 1985
TL;DR: In this article, an experimental study of the polarization properties of conventional low-birefringence nominally circular-core installed single mode fiber cables is reported, showing that the orthogonality of the two launched polarization components is preserved to within 2°, and the total power distributed between the two linear orthogonal components, when normalized with respect to the launched power, is effectively constant over time.
Abstract: An experimental study of the polarization properties of conventional low-birefringence nominally circular-core installed single mode fiber cables is reported. The results of the measurements indicate (1) The orthogonality of the two launched polarization components is preserved to within 2°, (2) the total power distributed between the two linear orthogonal components, when normalized with respect to the launched power, is effectively constant over time, and (3) given a linearly polarized input, the state of polarization varies over a time scale of minutes with time, but the degree of polarization exceeded 90% and remained stable for periods as long as 65 hours.
TL;DR: The photon statistics of a single spatial mode of the optical field (including the two polarization states) resulting from a single-photon state undergoing unsaturated amplification by a two-level medium are derived in this article.
Abstract: The photon statistics of a single spatial mode of the optical field (including the two polarization states) resulting from a single-photon state undergoing unsaturated amplification by a two-level medium are derived. Results are compared with those for an idealized noiseless linear amplifier and a conventional quantum-noise-limited amplifier in the limit of no gain. When the amplified field is divided for detection of different polarization states, distinctive polarization biases and correlations are evident on average when the polarization of the input state is constant. However, the results are insufficient to determine the initial polarization state based on a single measurement. If one must average over two orthogonally polarized input states (e.g., an incoherent mixture of either linearly or circularly polarized initial states) as required in the absence of hidden variable information in an Einstein–Podolsky-Rosen experiment, the distinctions are completely erased.
TL;DR: In this paper, an analysis and experimental results are described for the automatic polarization control of the polarization plane of the output light from a singlemode fiber with a standard axisymmetric core.
Abstract: An analysis and experimental results are described for the automatic polarization control of the polarization plane of the output light from a single-mode fiber with a standard axisymmetric core. This automatic polarization control device consists of two phase shifters made of z-cut LiNbO3 exhibiting the electrooptic effect. The phase shifters are oriented with their transverse planes inclined to each other. The state of the polarization is detected by two Rochon prisms and is fed back to the phase shifters. The analysis has been done for the change of the polarization of the incident light in the polarization control device. The range of the voltage applied to the phase shifter for the control and the condition of the angle between the phase shifters are clarified. Next, experiments have been performed and the single polarization control in the desired direction has been attained. A proposal is made to simplify the control mechanism.
TL;DR: In this paper, visual observations of a chiral smectic C phase were made simultaneously with the measurement of spontaneous polarization to understand the relation between the stripe pattern (the surface disclination) and the polarization reversal process.
Abstract: Visual observations of a chiral smectic C phase were made simultaneously with the measurement of the spontaneous polarization to understand the relation between the stripe pattern (the surface disclination) and the polarization reversal process. The polarization reverse is not directly related to the dynamical change of the stripe pattern. During the polarization reverse, the bright and chaotic pattern were observed independent of the stripe pattern.
TL;DR: In this article, the degree of polarization of materials and optical components widely used in the near-millimetre region was measured in the wavelength interval 0.5-3 mm.
TL;DR: Polarization rotation using a modulated electric field is demonstrated in methyl fluoride vapor as a technique to reduce source noise in diode-laser absorption spectroscopy in this paper, and a comparison of this technique with amplitude modulation and Stark modulation is presented, showing that this technique decreases the effect of source noise and thus provides improved sensitivity.
Abstract: Polarization rotation using a modulated electric field is demonstrated in methyl fluoride vapor as a technique to reduce source noise in diode-laser absorption spectroscopy. A comparison of this technique with amplitude modulation and Stark modulation is presented, showing that this technique decreases the effect of source noise and thus provides improved sensitivity. A discussion is presented of the magnitude of the polarization rotation for different J, K rotational transitions that occur in a symmetric top. The effect of the crossing angle of the polarization analyzer on the polarization rotation signal and the source-noise reduction is studied in order to obtain the operating conditions for maximum signal-to-noise ratio.