Showing papers on "Birefringence published in 2013"
TL;DR: In this article, a metasurface lens that focuses light and controls its polarization at a wavelength of 2'μm is presented, which demonstrates high transmission and complete phase control within a subwavelength thickness at near-infrared frequencies.
Abstract: A metasurface lens that focuses light and controls its polarization at a wavelength of 2 μm is presented. This lens demonstrates high transmission and complete phase control within a subwavelength thickness at near-infrared frequencies. By cascading four patterned sheets, the efficiency is dramatically improved over more common single sheet designs. In addition, by utilizing anisotropic sheets, arbitrary birefringence can be achieved. A planar lens that both focuses light and converts its polarization from linear to circular is analyzed.
312 citations
TL;DR: It is shown how a combination of metal nanobrick and nanocross elements allows one to fully control the phase of reflected light for two orthogonal polarizations simultaneously, in relation to birefringent metal-backed metasurfaces.
Abstract: We numerically study the optical properties of metal-insulator-metal resonators and metasurfaces, emphasizing the presence of gap-surface plasmon (GSP) resonances and their connection to the optical response. In relation to birefringent metal-backed metasurfaces, we show how a combination of metal nanobrick and nanocross elements allows one to fully control the phase of reflected light for two orthogonal polarizations simultaneously. The approach is exemplified by the design of a gradient birefringent metasurface that reflects two orthogonal polarization states into +2 and −3 diffraction order, respectively, with a reflectivity up to ∼ 80% and in a broad wavelength range around the design wavelength of 800 nm. Finally, we introduce the concept of metascatterers, which are wavelength-sized polarization-sensitive scatterers.
289 citations
TL;DR: In this article, a nano-engineered photonic-crystal chiral beamplitter is proposed to split left and right-handed circularly polarized light in the wavelength region around 1.615 µm.
Abstract: The linearly polarizing beamsplitter1, 2 is a widely used optical component in photonics. It is typically built from a linearly birefringent crystal such as calcite, which has different critical reflection angles for s- and p-polarized light3, leading to the transmission of one linear polarization and angled reflection of the other. However, the analogue for splitting circularly polarized light has yet to be demonstrated due to a lack of natural materials with sufficient circular birefringence. Here, we present a nano-engineered photonic-crystal chiral beamsplitter that fulfils this task. It consists of a prism featuring a nanoscale chiral gyroid network4, 5, 6, 7, 8, 9, 10 and can separate left- and right-handed circularly polarized light in the wavelength region around 1.615 µm. The structure is fabricated using a galvo-dithered direct laser writing method and could become a useful component for developing integrated photonic circuits that provide a new form of polarization control.
271 citations
03 Sep 2013
TL;DR: In this paper, the mesogenic properties and physical chemical properties (viscosity, birefringence, refractive indices, dielectric anisotropy and elastic constants) of compounds being cyano, fluoro, isothiocyanato derivatives of biphenyl, terphenyl and quaterphenyl, tolane, phenyl tolane and phenyl ethynyl tolan, and biphenynyl-tolane are compared.
Abstract: Liquid crystals, compounds and mixtures with positive dielectric anisotropies are reviewed. The mesogenic properties and physical chemical properties (viscosity, birefringence, refractive indices, dielectric anisotropy and elastic constants) of compounds being cyano, fluoro, isothiocyanato derivatives of biphenyl, terphenyl, quaterphenyl, tolane, phenyl tolane, phenyl ethynyl tolane, and biphenyl tolane are compared. The question of how to obtain liquid crystal with a broad range of nematic phases is discussed in detail. Influence of lateral substituent of different kinds of mesogenic and physicochemical properties is presented (demonstrated). Examples of mixtures with birefringence ∆n in the range of 0.2–0.5 are given.
204 citations
TL;DR: The proposed nanoantenna metasurface can find applications in many optical devices, such as birefringent modulators, waveplates, polarizers, and splitters.
Abstract: An infrared reflectarray metasurface with engineered birefringent behavior is demonstrated. The array reradiates incoming light into two orthogonal, linearly polarized reflections. The reflectarray is composed of rectangular metallic patch nanoantennas placed on top of a grounded dielectric stand-off layer. The patches are designed to locally manipulate the phase front of the incoming wave. They tailor the reflection phase to transform the phase front on the surface to the one desired for both orthogonal polarizations at the same time. The proposed nanoantenna metasurface can find applications in many optical devices, such as birefringent modulators, waveplates, polarizers, and splitters.
202 citations
TL;DR: A novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called Magneto-plasmonic crystal, which allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.
Abstract: Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.
174 citations
TL;DR: The first experimental results on SOP evolution of vector soliton molecules with periodic polarisation switching between two and three SOPs and superposition of polarisation Switching with SOP precessing are presented.
Abstract: Two fundamental laser physics phenomena - dissipative soliton and polarisation of light are recently merged to the concept of vector dissipative soliton (VDS), viz. train of short pulses with specific state of polarisation (SOP) and shape defined by an interplay between anisotropy, gain/loss, dispersion, and nonlinearity. Emergence of VDSs is both of the fundamental scientific interest and is also a promising technique for control of dynamic SOPs important for numerous applications from nano-optics to high capacity fibre optic communications. Using specially designed and developed fast polarimeter, we present here the first experimental results on SOP evolution of vector soliton molecules with periodic polarisation switching between two and three SOPs and superposition of polarisation switching with SOP precessing. The underlying physics presents an interplay between linear and circular birefringence of a laser cavity along with light induced anisotropy caused by polarisation hole burning.
109 citations
TL;DR: In this article, the polarization convertibility of asymmetric split-ring resonators with the polarization selectivity of S-shape resonators was integrated for realizing a composite-metamaterial-based 90-degree ultrathin polarization rotator (UTPR) with a 50.4-μm thickness in the terahertz gap region.
Abstract: We integrated the polarization convertibility of asymmetric split-ring resonators with the polarization selectivity of S-shape resonators for realizing a composite-metamaterial-based 90-degree ultrathin polarization rotator (UTPR) with a 50.4-μm thickness in the terahertz-gap region. By introducing the Fabry-Perot resonance into the UTPR, the measured transmission is maximized to 0.48 at 1.04 THz, leading to the polarization-conversion ratio up to 97.7%. Compared to other waveplates composed by pile-stacking birefringent metamaterials, the UTPR possesses less loss from the intrinsic resonances because it comprises only two layers of the resonators, and can evade from dichroism effects due to the unique working mechanism.
108 citations
TL;DR: A signal processing strategy that reconstructs the local retardation robustly in the presence of system PMD and benefits from the final averaging of the PMD-corrected retardation vectors of the spectral bins is presented.
Abstract: Polarization mode dispersion (PMD) has been recognized as a significant barrier to sensitive and reproducible birefringence measurements with fiber-based, polarization-sensitive optical coherence tomography systems. Here, we present a signal processing strategy that reconstructs the local retardation robustly in the presence of system PMD. The algorithm uses a spectral binning approach to limit the detrimental impact of system PMD and benefits from the final averaging of the PMD-corrected retardation vectors of the spectral bins. The algorithm was validated with numerical simulations and experimental measurements of a rubber phantom. When applied to the imaging of human cadaveric coronary arteries, the algorithm was found to yield a substantial improvement in the reconstructed birefringence maps.
108 citations
TL;DR: This work has demonstrated the polarization manipulation of light by employing a thin subwavelength slab of metamaterial with an extremely anisotropic effective permittivity tensor and suggested all-optical ultrafast control of reflected or transmitted light polarization by employing metal nonlinearities.
Abstract: One of the basic functionalities of photonic devices is the ability to manipulate the polarization state of light Polarization components are usually implemented using the retardation effect in natural birefringent crystals and, thus, have a bulky design Here, we have demonstrated the polarization manipulation of light by employing a thin subwavelength slab of metamaterial with an extremely anisotropic effective permittivity tensor Polarization properties of light incident on the metamaterial in the regime of hyperbolic, epsilon-near-zero, and conventional elliptic dispersions were compared We have shown that both reflection from and transmission through λ/20 thick slab of the metamaterial may provide nearly complete linear-to-circular polarization conversion or 90° linear polarization rotation, not achievable with natural materials Using ellipsometric measurements, we experimentally studied the polarization conversion properties of the metamaterial slab made of the plasmonic nanorod arrays in different dispersion regimes We have also suggested all-optical ultrafast control of reflected or transmitted light polarization by employing metal nonlinearities
106 citations
TL;DR: In this article, a highly birefringent photonic crystal fiber based on a modified octagonal structure for broadband dispersion compensation covering the S, C, and L-communication bands is proposed.
TL;DR: In this article, an ultrashort pulse laser induced formation of birefringent structures in the volume of different glasses: Borofloat 33, BK7 and ULE™.
Abstract: We report on the ultrashort pulse laser induced formation of birefringent structures in the volume of different glasses: Borofloat 33, BK7 and ULE™. Using polarization contrast and scanning electron microscopy we could prove that this birefringence is induced by nanogratings. We were able to identify the pulse duration as a crucial process parameter for the generation of nanogratings in these glasses. The achieved birefringence in ULE is comparable to fused silica, while borosilicate glasses show much less birefringence (only about 12%). Remarkably, the period of the nanogratings is also dependent on the type of the glass, being 250 nm for ULE and only 60 nm in case of Borofloat 33.
TL;DR: In this article, the authors present the current status of the BMV experiment and present the data acquisition and analysis procedure which takes into account the symmetry properties of the raw data with respect to the orientation of the magnetic field and the sign of the cavity birefringence.
Abstract: We present the current status of the BMV experiment. Our apparatus is based on an up-to-date resonant optical cavity coupled to a transverse magnetic field. We detail our data acquisition and analysis procedure which takes into account the symmetry properties of the raw data with respect to the orientation of the magnetic field and the sign of the cavity birefringence. The measurement result of the vacuum magnetic linear birefringence k_\mathrm{CM}$ presented in this paper was obtained with about 200 magnetic pulses and a maximum field of 6.5\,T, giving a noise floor of about $8 \times 10^{-21}$\,T$^{-2}$ at $3\sigma$ confidence level.
TL;DR: An alternative use of the LC-PolScope for imaging the polarization dependent transmittance of dichroic materials is described, explaining the minor changes needed to convert the instrument between the two imaging modes, and discussing the relationship between the quantities measured with either instrument.
Abstract: Polarized light microscopy provides unique opportunities for analyzing the molecular order in man-made and natural materials, including biological structures inside living cells, tissues, and whole organisms. 20 years ago, the LC-PolScope was introduced as a modern version of the traditional polarizing microscope enhanced by liquid crystal devices for the control of polarization, and by electronic imaging and digital image processing for fast and comprehensive image acquisition and analysis. The LCPolScope is commonly used for birefringence imaging, analyzing the spatial and temporal variations of the differential phase delay in ordered and transparent materials. Here we describe an alternative use of the LC-PolScope for imaging the polarization dependent transmittance of dichroic materials. We explain the minor changes needed to convert the instrument between the two imaging modes, discuss the relationship between the quantities measured with either instrument, and touch on the physical connection between refractive index, birefringence, transmittance, diattenuation, and dichroism.
TL;DR: It turns out that the degenerate left- and right-circularly polarized modes of the untwisted PCF are not 100% circularly polarized but carry a small amount of orbital angular momentum caused by the interaction between the core mode and the hollow channels.
Abstract: In this Letter we show that, in spectral regions where there are no orbital cladding resonances to cause transmission loss, the core mode of a continuously twisted photonic crystal fiber (PCF) exhibits optical activity, and that the magnitude of the associated circular birefringence increases linearly with twist rate and is highly reproducible. In contrast to previous work on twist-induced circular birefringence, PCF has zero linear birefringence and an on-axis core, making the appearance of circular birefringence rather unexpected. A theoretical model based on symmetry properties and perturbation theory is developed and used to show that both spin and orbital angular momentum play a role in this effect. It turns out that the degenerate left- and right-circularly polarized modes of the untwisted PCF are not 100% circularly polarized but carry a small amount of orbital angular momentum caused by the interaction between the core mode and the hollow channels.
TL;DR: The LC-PolScope was introduced as a modern version of the traditional polarizing microscope enhanced by liquid crystal devices for the control of polarization, and by electronic imaging and digital image processing for fast and comprehensive image acquisition and analysis.
Abstract: Polarized light microscopy provides unique opportunities for analyzing the molecular order in man-made and natural materials, including biological structures inside living cells, tissues, and whole organisms. 20 years ago, the LC-PolScope was introduced as a modern version of the traditional polarizing microscope enhanced by liquid crystal devices for the control of polarization, and by electronic imaging and digital image processing for fast and comprehensive image acquisition and analysis. The LC- PolScope is commonly used for birefringence imaging, analyzing the spatial and temporal variations of the differential phase delay in ordered and transparent materials. Here we describe an alternative use of the LC-PolScope for imaging the polarization dependent transmittance of dichroic materials. We explain the minor changes needed to convert the instrument between the two imaging modes, discuss the relationship between the quantities measured with either instrument, and touch on the physical connection between refractive index, birefringence, transmittance, diattenuation, and dichroism.
TL;DR: Theoretical results indicate that the single-mode THz wave in the frequency range from 0.73 to 1.22 THz can be guided in the fiber; the birefringence can be enhanced by rotating the major axis of the elliptical air-hole and there exists an optimal rotating angle at 30°.
Abstract: A new kind of polymer porous fiber with elliptical air-holes is designed for obtaining high birefringence in the terahertz (THz) frequency range in this paper. Using the finite element method, the properties of this kind of fiber are simulated in detail including the single-mode propagation condition, the birefringence, and the loss. Theoretical results indicate that the single-mode THz wave in the frequency range from 0.73 to 1.22 THz can be guided in the fiber; the birefringence can be enhanced by rotating the major axis of the elliptical air-hole and there exists an optimal rotating angle at 30°. At this optimal angle a birefringence as high as 0.0445 can be obtained in a wide frequency range. Low-loss THz guidance can be achieved owing to the effective reduction of the material absorption in such a porous fiber. This research is useful for polarization-maintaining THz-wave guidance.
TL;DR: Analysis shows that the tension-induced shift in resonance wavelength is determined both by the photoelastic effect and by the change in twist rate, while the torsion-induced wavelength shift depends only on the change on twist rate.
Abstract: Solid-core photonic crystal fiber (PCF) with a permanent helical twist exhibits dips in its transmission spectrum at certain wavelengths. These are associated with the formation of orbital angular momentum states in the cladding. Here we investigate the tuning of these states with mechanical torque and axial tension. The dip wavelengths are found to scale linearly with both axial strain and mechanical twist rate. Analysis shows that the tension-induced shift in resonance wavelength is determined both by the photoelastic effect and by the change in twist rate, while the torsion-induced wavelength shift depends only on the change in twist rate. Twisted PCF can act as an effective optically monitored torque-tension transducer, twist sensor, or strain gauge.
TL;DR: This paper will focus on the investigation of birefringent fibrous samples, where specific results will be discussed in detail and should give a comprehensive view on the recent achievements in the measurements of THz bireFringence.
Abstract: In the last few years, various studies on terahertz (THz) birefringence have been presented, based on polarization-sensitive THz time-domain spectroscopy. The field of THz birefringence is a wide one covering several aspects, such as different materials exhibiting THz birefringence, polarization-sensitive THz technology, as well as numerous methods for extracting the birefringence properties of a sample from the THz data. Therefore, this paper aims at reviewing recent results on THz birefringence measurements presented in literature, addressing the above aspects and giving an overview of the topic. Moreover, it will focus on the investigation of birefringent fibrous samples, where specific results will be discussed in detail. Altogether, this paper should give a comprehensive view on the recent achievements in the measurements of THz birefringence.
TL;DR: Methods for measuring and compensating the nonlinear electro-optical effect of transmissive, parallel-aligned liquid crystal (LC)-based spatial light modulators (SLMs) are presented and the LC-SLM's experimental demonstration finally verifies the resultant improvement in holographic imaging.
Abstract: Methods for measuring and compensating the nonlinear electro-optical effect of transmissive, parallel-aligned liquid crystal (LC)-based spatial light modulators (SLMs) are presented. Particularly, the analysis is focused on the spatial nonuniformity of the voltage versus phase modulation characteristics for an active-matrix-driven, electrically controlled birefringence type LC-SLM. A high-quality reconstruction from phase-only modulating SLMs requires a well-calibrated phase addressing across the entire SLM panel. I discuss how the commonly inherent phase-response inhomogeneity of LC-SLM is characterized by purposeful localized measurement techniques. This phase-response inhomogeneity is efficiently compensated by utilizing a Legendre polynomial representation in combination with a remapping of an 8 bit gray level addressing. The calibration procedure is corroborated by measurement data. The LC-SLM's experimental demonstration finally verifies the resultant improvement in holographic imaging.
TL;DR: In this paper, the refractive index and absorption coefficient of the liquid crystal mixtures 1852 and 1825 in the frequency range between 0.2 and 2.5 THz were presented.
Abstract: With growing interest in switchable devices for the THz frequency range, there is a strong demand for liquid crystals (LC) exhibiting both a high birefringence and a low absorption. We present the refractive index and absorption coefficient of the liquid crystal mixtures 1852 and 1825 in the frequency range between 0.2 and 2.5 THz. Both mixtures are designed specifically for high birefringence Δn of 0.32 and 0.38, respectively, in the THz region. In addition, they show low absorption coefficients for both ordinary and extraordinary polarization. This low absorbance in combination with the high birefringence makes these LCs particularly well suited for applications in switchable devices for THz optics.
TL;DR: Strain associated with the replacement of aspirin molecules by salicylic acid molecules in the crystal structure is computed to be large enough to work as the driving force for the twisting of crystallites.
Abstract: Banded spherulites of aspirin have been crystallized from the melt in the presence of salicylic acid either generated from aspirin decomposition or added deliberately (2.6–35.9 mol %). Scanning electron microscopy, X-ray diffraction analysis, and optical polarimetry show that the spherulites are composed of helicoidal crystallites twisted along the ⟨010⟩ growth directions. Mueller matrix imaging reveals radial oscillations in not only linear birefringence, but also circular birefringence, whose origin is explained through slight (∼1.3°) but systematic splaying of individual lamellae in the film. Strain associated with the replacement of aspirin molecules by salicylic acid molecules in the crystal structure is computed to be large enough to work as the driving force for the twisting of crystallites.
TL;DR: In this article, the negative dielectric anisotropy (Δe) liquid crystal for fringing field switching (n-FFS) display was compared with positive and negative Δe liquid crystal.
Abstract: We report a high performance negative dielectric anisotropy (Δe) liquid crystal for fringing field switching (n-FFS) display. We compare the electro-optic characteristics of FFS cells using positive and negative Δe LCs. With comparable driving voltage and response time, the n-FFS cell has advantages in higher transmittance, single gamma curve, less cell gap sensitivity and slightly wider viewing angle. LC director deformation distribution is analyzed to explain these performance differences.
TL;DR: In order to improve the accuracy and long-term stability of the frequency-locking performance, a power stabilization module is added, and the dependences of the peak-to-peak amplitude and frequency difference of the polarization spectroscopy signal on various pump and probe powers are investigated.
Abstract: Polarization spectroscopy in (4)He around 1083 nm is observed and optimized with a distributed feedback fiber laser and is applied for frequency stabilization. In order to improve the accuracy and long-term stability of the frequency-locking performance, a power stabilization module is added, and the dependences of the peak-to-peak amplitude and frequency difference (width) of the polarization spectroscopy signal on various pump and probe powers are investigated.
TL;DR: In this article, a self-assembled gold nanorod array was observed to have a birefringence and thin film texture similar to common organic nematic liquid crystal textures between crossed polarizers.
Abstract: Fascinating nematic- and smectic-like self-assembled arrays are observed for gold nanorods partially capped with either laterally or terminally attached nematic liquid crystals upon slow evaporation of an organic solvent on TEM grids. These arrays can be manipulated and reoriented by applying an external magnetic field from quasi-planar to vertical similar to a Freedericksz transition of common organic nematic liquid crystals. Birefringence and thin film textures of these self-assembled gold nanorod arrays observed by polarized optical microscopy are strongly reminiscent of common organic nematic liquid crystal textures between crossed polarizers and, additionally, support the formation of ordered liquid crystal-like anisotropic superstructures. The ordering within these arrays is also confirmed in bulk samples using small angle X-ray scattering (SAXS).
TL;DR: High birefringent fiber Bragg gratings in standard single-mode optical fiber realized with UV femtosecond pulses and line-by-line inscription are reported, which is to the authors' knowledge the highest bireFringence value reported so far.
Abstract: We report highly birefringent fiber Bragg gratings in standard single-mode optical fiber realized with UV femtosecond pulses and line-by-line inscription By controlling the three-dimensional positioning of the focused laser beam with respect to the fiber core, we achieve very high birefringence at the grating location in a single exposure A maximum birefringence value of 793×10−4 has been reached for 10th-order gratings when using 2 μJ pulses, which is to our knowledge the highest birefringence value reported so far This birefringence results from UV-induced high-densification lines shifted from the center of the core, increasing the asymmetry of the induced-stress lines With a Bragg wavelength spacing reaching more than 800 pm between polarization modes, such gratings are particularly well suited for selective filtering or, as demonstrated here, for temperature-insensitive transverse-strain measurements
TL;DR: A discrete set of continuous deformation of a circular nanoslit to generate and control optical vortices at the microscopic scale is proposed and topological shaping of light is experimentally demonstrated in the visible domain.
Abstract: We propose a discrete set of continuous deformation of a circular nanoslit to generate and control optical vortices at the microscopic scale. The process relies on the interplay between the spin and orbital angular momentum degrees of freedom of light mediated by appropriate closed-path nanoslits milled on a thin gold film. Topological shaping of light is experimentally demonstrated in the visible domain. Moreover, all experimental observations are quantitatively validated by a simple model that takes into account the transverse manipulation of the optical phase via the space-variant form birefringence of subwavelength slits.
TL;DR: This study suggests that a gold-filled PCF coupler is a new possibility for applications on polarization beam splitters and polarizers.
Abstract: We numerically investigate the polarization-dependent coupling in dual-core photonic crystal fibers (PCFs) selectively filled with gold wires in air holes. It is shown that the even and odd supermodes exhibit significantly different dispersion and loss when one gold wire is filled in between two cores. The enhanced birefringence and polarization-dependent attenuation of the supermodes support the separation of two orthogonally polarized components as well as polarization-dependent transmissions with a high degree of polarization in gold-filled dual core PCFs. Our study suggests that a gold-filled PCF coupler is a new possibility for applications on polarization beam splitters and polarizers.
TL;DR: In this paper, the temperature dependencies of dielectric permittivities, birefringence, splay K1 and bend K3 elastic constants were measured, and the splay viscosity ηsplay and the flow viscosities η|| and η⊥ were smaller than the visosities measured for the symmetric V-shaped bent-core materials at similar temperatures.
Abstract: Molecular shape is an important factor in determining the material properties of thermotropic liquid crystals (LCs). We synthesized and investigated several LC compounds formed by asymmetrically bent molecules with a rigid four-ring core in the shape of the letter ‘L’. We measured the temperature dependencies of dielectric permittivities, birefringence, splay K1 and bend K3 elastic constants, splay viscosity ηsplay and flow viscosities η|| and η⊥. The bend–splay anisotropy δK31 = K3 − K1 is negative, similar to the case of nematic LCs formed by symmetrically bent molecules of V-shape. The dielectric anisotropy Δe and birefringence are positive in the entire nematic range. The splay viscosity ηsplay and the flow viscosities η|| and η⊥ are smaller than the viscosities measured for the symmetric V-shaped bent-core materials at similar temperatures. The ratio Γ = ηsplay/η||,⊥ is in the range 5–4 that is typical for rod-like LCs. The reported L-shaped bent-core nematic LCs combine the useful features of bent-core LCs (such as a negative δK31, suitable for formulation of broad-range blue phases) with the relatively low viscosities, a property typical for rod-like LCs and beneficial for electro-optic switching applications.
TL;DR: This Letter reported on an ultrahigh birefringence photonic crystal fiber with a germanium-doped elliptical core, which is fabricated in the lab using the stack-and-draw method, and demonstrated the capability to simultaneously measure the FBG's pressure and temperature experimentally.
Abstract: In this Letter, we reported on an ultrahigh birefringence photonic crystal fiber (PCF) with a germanium-doped elliptical core, which is fabricated in our lab using the stack-and-draw method. An ultrahigh birefringence of 1.1×10(-2) is obtained experimentally, which is close to the theoretical value of 1.4×10(-2) at the wavelength of 1550 nm. To our knowledge, this is the highest birefringence reported to date for fabricated index-guiding PCF. Fiber Bragg gratings (FBG) were written in the fiber to confirm its ultrahigh birefringence, and we demonstrated the capability to simultaneously measure the FBG's pressure and temperature experimentally. Because of the large separation of the two FBG peaks (>12 nm), such fiber is a promising candidate for a single polarization device.