Optical Rotator Research Articles

Chronic olanzapine treatment leads to increased opioid receptor expression and changes in feeding regulating neurons in the female rat hypothalamus

Opioid receptor antagonists have shown increasing promise as an adjunct therapy to psychotropic medication. The goal is to reduce the weight gain and metabolic adverse effects that are associated with certain second-generation antipsychotics, such as olanzapine and clozapine. In this study, female rats were treated for 4 weeks with a long-acting injectable formulation of olanzapine to assess effects on hypothalamic feeding regulation. Using quantitative spatial in situ hybridization and receptor autoradiography, expression levels of the mu, kappa and delta opioid receptors were defined in the five hypothalamic areas: paraventricular nucleus (PVN), arcuate nucleus (ARC), ventromedial nucleus (VMN), dorsomedial nucleus (DMN) and lateral hypothalamus (LH). In addition, hypothalamic neuron number and size were estimated using the unbiased optical fractionator and spatial rotator methods. Hyperphagia was observed after only 24 hours of olanzapine treatment, with continued weight gain throughout the duration of the study. In contrast, the observed food intake reversed to control levels after 2 weeks of olanzapine treatment. Chronic olanzapine treatment increased expression of kappa opioid receptor mRNA and receptor availability in the PVN, as well as increased mu opioid receptor availability in the PVN, ARC and VMN. These changes were accompanied by fewer anorexigenic proopiomelanocortin-expressing neurons of the ARC and corticotropin-releasing hormone expressing neurons of the PVN. This study links olanzapine-driven metabolic effects to increased opioid receptor expression in the hypothalamus, thus providing a rationale for the positive effects of using opioid receptor antagonists to relieve olanzapine adverse effects.

Effect of surface anchoring energy on a liquid crystal optical waveguide-based polarization rotator

This study reports the effect of the surface anchoring energy of a liquid crystal (LC) cell on the performance of the liquid crystal optical waveguide polarization rotator (LCOW-PR) for the purpose of providing a theoretical reference for practical preparation of the LCOW-PR. First, the expression for the deflection angle of the director at the boundary of the LC cell is derived so that the distributions of the director and dielectric tensor of the LC can be accurately solved under any anchoring energy. On this basis, the correlation between the crucial indicators such as the polarization conversion length (PCL) together with the polarization conversion efficiency (PCE) of the LCOW-PR and the anchoring effect strength is constructed by combining with the existing numerical algorithms. The numerical results show that the maximum variation of the PCL is lower than 0.1 µm as the anchoring effect strength increases from 1×10−6J/m2 to 1×10−3J/m2, while the PCE decreases from 99.72% to 78.33%. This implies that the PCL of the LCOW-PR does not depend on the surface anchoring energy, but the anchoring effect strength of the orientational layer must be controlled to the order of 10−6J/m2 or even lower to achieve high-performance conversion between the polarization modes. Simultaneously, the effectiveness of the calculations in this work is verified with the help of the coupled mode theory as well as a comparison to previous reports.

Multilevel asymmetric coupler MAC field rotator for LP11 mode in few mode fiber

In this work, we present a new design for an integrated optical field rotator for the mode LP11a to the mode LP11b and vice versa using planar Silica over silicon technology. The structure is designed using a Multilayer Asymmetric Coupler. The coupling efficiency of the coupler could be as high as 99% when its length is about 1 mm. For a shorter coupler of length 550 microns and a coupling efficiency of 91%, a complete structure is designed to couple 2 few mode fibers of diameters 15.4 microns through an inverted taper from one side and a Y junction with two inverted tapers from the other side. The fiber to fiber insertion loss of the proposed structure is less than 3 dB over about 190 nm spectral range around 1550 nm. The 3 dB bandwidth of the structure is greater than 360 nm as demonstrated by the Beam Propagation Method BPM simulation.

Miniaturized optical polarization rotator on a microfiber loop using Berry’s phase

Control of optical polarization plays a key role in various fields of optical science and engineering. Light propagating along an out-of-plane path acquires a Berry's phase, which rotates the polarization of the incident light. Herein, a miniaturized optical polarization rotator based on a microfiber loop is proposed and demonstrated with large polarization deflection angle (∼85°) with low insertion loss (∼1 dB). It operates over a wide bandwidth from 1400 nm to 1650 nm, because the Berry’s phase only depends on the optical path. Moreover, the influence of geometric structures on the performance of the microfiber-loop device, including mode cross-talk, birefringence and working bandwidth, are systematically explored. This work provides an alternative scheme to realize optical microfiber polarization rotators, which can be readily used in optical fiber sensors and polarimetric interferometry.

Non-reciprocal wave retarder based on optical rotators combination

We propose and demonstrate a method to realize an easily tunable non-reciprocal wave retarder whose phase retardation depends on the light propagation direction. The system is based on a combination of a reciprocal polarization rotator, a non-reciprocal magneto-optical rotator, and two quarter-wave plates. Experimental tests demonstrate various non-reciprocal functionalities in complete agreement with the underlying theoretical concept.

Ultrashort optical pulse polarization rotator based on azimuth angle rotation in semiconductor optical amplifier

For the first time, a dynamic model is used to design all-optical polarization rotator for ultrashort pulse in semiconductor optical amplifier (SOA). When 200 fs probe and pump pulses co-propagate in SOA, the azimuth angle of probe polarization is rotated by pump energy due to SOA nonlinearities. As a result of azimuth angle rotation (AAR) phenomenon, the state of polarization (SOP) of probe pulse also rotates. In addition to the pump energy, AAR also depends on the input probe pulse characteristics and the SOA bias current. The input probe characteristics include its input energy level, input Stokes vector, and input degree of polarization. The results of our research indicate that the output probe azimuth angle can be rotated up to 113 deg by the mentioned factors. Consequently, the probe SOP can be changed from the quasihorizontal state to the quasivertical state.

Achromatic polarization rotator with tunable rotation angle

We theoretically suggest and experimentally demonstrate a broadband composite optical rotator that is capable of rotating the polarization plane of a linearly-polarized light at any chosen angle. The device is composed of an even number of half-wave plates (WPs) rotated at specific angles with respect to their fast-polarization axes. The frequency bandwidth of the polarization rotator in principal increases with the number of half-WPs. Here we experimentally examine the performance of rotators composed of two, four, six, eight and ten half-WPs.

Stereological estimation of particle shape from vertical sections.

In the present paper, we describe a new simple stereological method of estimating volume tensors in 3D from vertical sections. The volume tensors provide information about particle shape in 3D. In a model-based setting, the method requires that the particle distribution is invariant under rotations around the vertical axis. In a design-based approach, where the vertical section is uniformly rotated around the vertical axis, the method provides information about an index of elongation of the particles in the direction of the vertical axis. The method has been implemented on human brain tissue for the analysis of neurons in layer III of the medial frontal gyrus of Brodmann Area 46. In the actual implementation, the new estimator shows similar precision as an earlier estimator, based on an optical rotator design, but it is a factor3 faster to collect the measurements for the new estimator. Furthermore, the calculations needed for determining the new estimator are muchsimpler. LAY DESCRIPTION: A new method is described for estimating volume tensors in 3 dimensions based on the stereological method: planar rotator. In general, volume tensors may provide information about particle volume, shape and direction. The new estimator was implemented on human brain tissue for the analysis of neurons in layer III of the medial frontal gyrus on Brodmann Area 46 and compared to a previous published method, based on an optical rotator design. The new estimator shows similar precision as the earlier estimator, but it is a factor 3 faster to collect the measurements. Besides, the calculations behind the new estimator are simpler and easier to implement to a software program.

Ion irradiated magneto-optic waveguide based on TGG crystal

Here we report the fabrication of a magneto-optic waveguide based on TGG crystal via 15 MeV C3+ ion irradiation. The ion irradiation process leads to the optical anisotropy in the as-irradiated TGG waveguide, which hinders the magneto-optical rotation in the waveguide. To remove the irradiation-induced optical anisotropy, we annealed the as-irradiated TGG waveguide under different conditions. After annealing at 400 °C for one hour, the magneto-optical rotation of 14° per centimeter is observed in the waveguide at the wavelength of 632.8 nm, under the magnetic field of 0.24 T, which is comparable to that observed in the TGG crystal under the same magnetic field. This work paves the way for applications of TGG waveguides as integrated optical rotators and isolators.

Comprehensive characterization of a general composite waveplate by spectroscopic Mueller matrix polarimetry.

Composite waveplates (CWs) consisting of multiple single waveplates are basic polarization elements and widely used to manipulate the polarized light in optical systems, and their performances affect the final accuracy and precision significantly. This research proposes a method for the comprehensive characterization of an arbitrary CW based on spectroscopic Mueller matrix polarimetry. An analytical model is established to describe a general CW by extending Jones' equivalent theorem with Mueller matrix calculus. In this model, an arbitrary CW is optically equivalent to a cascaded system consisting of a linear retarder with slight diattenuation followed by an optical rotator, and its polarization properties are completely described by four polarization parameters, including the retardance, the fast axis azimuth, the rotation angle, and the diattenuation angle. Analytical relations between the polarization properties, the structure, and the Mueller matrix of the CW are then derived from the established model. By the proposed method, the polarization parameters of an arbitrary CW can be comprehensively characterized over an ultra-wide spectral range via only one measurement. Moreover, the actual structure of the CW, including the thicknesses and fast axis azimuths of the single waveplates, as well as the axis alignment errors, can be completely reconstructed from the polarization spectra. Experiments performed with a house-developed broadband Mueller matrix polarimeter on three typical CWs including a compound zero-order waveplate, an achromatic waveplate and a specially designed biplate have demonstrated the capability of the proposed method.

Optical Planar Waveguides Fabricated by Using Carbon Ion Implantation in Terbium Gallium Garnet

Optical planar waveguides in terbium-gallium-garnet (TGG) crystals are promising photonic devices, particularly for optical isolators and rotators. In this work, to the best of our knowledge, we report on the fabrication and the characterization of TGG waveguides for the first time. The fabrication procedure involved carbon ion implantation at an energy of 6.0 MeV and a fluence of 5.0×1014 ions/cm2. The effective refractive indices of the propagation modes in the carbonimplanted waveguide were measured by using the prism-coupling technique. The profile of the refractive index and the distribution of the near-field intensity were calculated by using the reflectivity calculation method and the finite-difference beam propagation method, respectively. The carbon-implanted TGG waveguide is considered to be a candidate for a magneto-optical photonic device.

Интегрально-оптический преобразователь поляризации излучения на основе асимметричного волновода в стекле

Интегрально-оптический преобразователь поляризации излучения на основе асимметричного волновода в стекле

Optical rotation compensation for a holographic 3D display with a 360 degree horizontal viewing zone.

A method for a continuous optical rotation compensation in a time-division-based holographic three-dimensional (3D) display with a rotating mirror is presented. Since the coordinate system of wavefronts after the mirror reflection rotates about the optical axis along with the rotation angle, compensation or cancellation is absolutely necessary to fix the reconstructed 3D object. In this study, we address this problem by introducing an optical image rotator based on a right-angle prism that rotates synchronously with the rotating mirror. The optical and continuous compensation reduces the occurrence of duplicate images, which leads to the improvement of the quality of reconstructed images. The effect of the optical rotation compensation is experimentally verified and a demonstration of holographic 3D display with the optical rotation compensation is presented.

Highly efficient silicon optical polarization rotators based on mode order conversions.

We design and demonstrate the novel silicon optical polarization rotators (PRs) based on the TM(0)-TE(n)-TE(0) mode conversions inside the waveguide. The TM(0)-TE(n) mode converters are realized by the mode hybridization of the tapered rib waveguides. The TE(n)-TE(0) mode converters based on the beam shaping method are followed to complete the PRs function. By using the TE(1), TE(2), and TE(3) mode as the transitional mode, the fabricated PRs show the insert losses of less than 0.4, 0.5, and 1 dB, respectively. The corresponding polarization extinction ratios of larger than 21, 18, and 23 dB, over a wavelength range of 100 nm.

Stereological estimation of particle shape and orientation from volume tensors.

In the present paper, we describe new robust methods of estimating cell shape and orientation in 3D from sections. The descriptors of 3D cell shape and orientation are based on volume tensors which are used to construct an ellipsoid, the Miles ellipsoid, approximating the average cell shape and orientation in 3D. The estimators of volume tensors are based on observations in several optical planes through sampled cells. This type of geometric sampling design is known as the optical rotator. The statistical behaviour of the estimator of the Miles ellipsoid is studied under a flexible model for 3D cell shape and orientation. In a simulation study, the lengths of the axes of the Miles ellipsoid can be estimated with coefficients of variation of about 2% if 100 cells are sampled. Finally, we illustrate the use of the developed methods in an example, involving neurons in the medial prefrontal cortex of rat.

Analysis of a segmented q-plate tunable retarder for the generation of first-order vector beams.

In this work we study a prototype q-plate segmented tunable liquid crystal retarder device. It shows a large modulation range (5π rad for a wavelength of 633 nm and near 2π for 1550 nm) and a large clear aperture of one inch diameter. We analyze the operation of the q-plate in terms of Jones matrices and provide different matrix decompositions useful for its analysis, including the polarization transformations, the effect of the tunable phase shift, and the effect of quantization levels (the device is segmented in 12 angular sectors). We also show a very simple and robust optical system capable of generating all polarization states on the first-order Poincaré sphere. An optical polarization rotator and a linear retarder are used in a geometry that allows the generation of all states in the zero-order Poincaré sphere simply by tuning two retardance parameters. We then use this system with the q-plate device to directly map an input arbitrary state of polarization to a corresponding first-order vectorial beam. This optical system would be more practical for high speed and programmable generation of vector beams than other systems reported so far. Experimental results are presented.

Enhancing the output bandwidth of a chirped-pulse Ti:S multipass amplifier via optical rotatory dispersion

In this paper, we present theoretically a simple and passive method to modulate the output spectrum of a broadband multi-pass Ti:S amplifier by means of polarization-dependent gain and optical rotator dispersion (ORD). By choosing the ORD and two π-polarization wavelengths, we can shape the effective gain section flexibly in order to suppress spectral narrowing and red-shift effects. Our simulations show the amplifier we have designed can scale a 0.4nJ, 10fs seed pulse up to 3.31mJ almost without spectral narrowing and central wavelength-shift. Increasing the difference of the two π-polarization wavelengths can result in the saddle output spectrum with a span of about 149nm, which is very helpful for further laser amplification to avoid spectral narrowing.

Magneto-optic transmittance modulation observed in a hybrid graphene–split ring resonator terahertz metasurface

By placing a material in close vicinity of a resonant optical element, its intrinsic optical response can be tuned, possibly to a wide extent. Here, we show that a graphene monolayer, spaced a few tenths of nanometers from a split ring resonator metasurface, exhibits a magneto-optical response which is strongly influenced by the presence of the metasurface itself. This hybrid system holds promises in view of thin optical modulators, polarization rotators, and nonreciprocal devices, in the technologically relevant terahertz spectral range. Moreover, it could be chosen as the playground for investigating the cavity electrodynamics of Dirac fermions in the quantum regime.

Intra-cavity spectral shaping based on optical rotatory dispersion in a broadband Ti : S regenerative amplifier

We theoretically present a passive method for intra-cavity spectral shaping in a broadband Ti : S regenerative amplifier on optical rotatory dispersion (ORD). Besides a polarization-dependent Ti : S gain crystal, implementing the method requires a broadband half-wave plate and a wedge pair made of an optical rotator crystal for an adjustable ORD. Our calculations show inducing proper ORD allows the amplifier to boost an 800 nm pulse from sub-nJ up to 3.18 mJ with a bandwidth of 94.5 nm without peak wavelength shift or spectral narrowing. For a certain ORD, this method allows us to get tunable broadband amplification with almost constant output pulse energy by simply rotating the half-wave plate. In spite of its flexibility in controlling the output spectrum of the amplifier, this method is very simple to align.

Tunable and switchable polarization rotation with non-reciprocal plasmonic thin films at designated wavelengths

A tunable and switchable ultrathin-film optical rotator with a variable working wavelength is experimentally realized by a team in Germany. Scientists at the University of Stuttgart and the Max Planck Institute for Solid State Research fabricated a plasmonic optical rotator for visible light whose polarization rotation can be continuously tuned and switched by applying a magnetic field. They realized this by combining a magneto-optical EuSe slab having a high Verdet constant and a high saturation magnetic flux density with a one-dimensional plasmonic gold grating. The unique dispersion properties of the structure enable free tuning of the working wavelength by varying the grating parameters. The team anticipates that the concept will lead to highly integrated non-reciprocal photonic devices for actively controlled light modulation, magnetic field sensing and optical isolation. Furthermore, the simple fabrication of EuSe nanostructures by physical vapour deposition opens the way for a wide range of magneto-plasmonic systems and three-dimensional magneto-optical metamaterials.