Birefringent Phase Retardation Research Articles

Rewritable color nanoprints in antimony trisulfide films.

Materials that exhibit large and rapid switching of their optical properties in the visible spectrum hold the key to color-changing devices. Antimony trisulfide (Sb2S3) is a chalcogenide material that exhibits large refractive index changes of ~1 between crystalline and amorphous states. However, little is known about its ability to endure multiple switching cycles, its capacity for recording high-resolution patterns, nor the optical properties of the crystallized state. Unexpectedly, we show that crystalline Sb2S3 films that are just 20 nm thick can produce substantial birefringent phase retardation. We also report a high-speed rewritable patterning approach at subdiffraction resolutions (>40,000 dpi) using 780-nm femtosecond laser pulses. Partial reamorphization is demonstrated and then used to write and erase multiple microscale color images with a wide range of colors over a ~120-nm band in the visible spectrum. These solid-state, rapid-switching, and ultrahigh-resolution color-changing devices could find applications in nonvolatile ultrathin displays.

Polarization holographic microscope slide for birefringence imaging of anisotropic samples in microfluidics.

Birefringence is an important optical property of anisotropic materials arising from anisotropies of tissue microstructures. Birefringence parameters have been found to be important to understand optical anisotropic architecture of many materials and polarization imaging has been applied in many researches in the field of biology and medicine. Here, we propose a scheme to miniaturize a double-channel polarization holographic interferometer optics to create a polarization holographic microscope slide (P-HMS) suitable for integrating with microfluidic lab-on-a-chip (LoC) systems. Based on the P-HMS combined with a simple reconstruction algorithm described in the paper, we can not only simultaneously realize holographic imaging of two orthogonal polarization components of dynamic samples in a microfluidic channel but also quantitative measurement of 2D birefringence information, both including the birefringence phase retardation and optic-axis orientation. This chip interferometer allows for off-axis double-channel polarization digital holographic recording using only a single illumination beam without need of any beam splitter or mirror. Its quasi-common path configuration and self-aligned design also make it tolerant to vibrations and misalignment. This work about the P-HMS could play a positive role in promoting the application of birefringence imaging in microfluidic LoC technology.

Babinet-bilayered geometric phase optical elements.

Geometric phase optical elements based on structured anisotropy are widely used for phase shaping via their orientational degree of freedom. To date, amplitude shaping via space-variant retardance is much less investigated, a practical reason being that the spin-orbit interaction of light couples retardance with the dynamic part of the optical phase. Inspired by the complementary diffractive elements associated with Babinet's principle, a bilayered subwavelength grating design is proposed in order to cancel out the spatial modulation of the dynamic phase usually associated with space-variant birefringent phase retardation. This concept is illustrated in the framework of single-mode Laguerre-Gauss beam shaping.

Broadband polarization conversion with anisotropic plasmonic metasurfaces

Metasurfaces offer exciting opportunities that enable precise control of light propagation, optical intensity, phase and polarization. Plasmonic metasurface based quarter-wave plates have been recently studied to realize the conversion between linear polarization and circular polarization. However, it is still quite challenging to directly measure the birefringent phase retardation introduced by metasurface wave plates with a reliable technique. Here, we report a high-performance broadband metasurface quarter-wave plate made of anisotropic T-shaped plasmonic antennas in near-infrared wavelength range, where the achromatic nearly 90° transmitted phase retardation through the metasurface is precisely characterized with an optical vortex based interferometric approach. Based on the measured transmission amplitude and phase of two orthogonal linear polarization components, nearly unit degree of linear polarization is extracted from the Stokes parameters, indicating excellent broadband polarization conversion between linearly and circularly polarized light through the metasurface. Our results will be an important step forward in the advancement of integrated metasurface devices for polarization conversion and beam manipulation, structured light control, as well as new spectroscopic and interferometric techniques for metasurface characterization.

Reflective Spin-Orbit Geometric Phase from Chiral Anisotropic Optical Media.

We report on highly reflective spin-orbit geometric phase optical elements based on a helicity-preserving circular Bragg-reflection phenomenon. First, we present a dynamical geometric phase experiment using a flat chiral Bragg mirror. Then, we show that shaping such a geometric phase allows the efficient spin-orbit tailoring of light fields without the need to fulfill any condition on birefringent phase retardation, in contrast to the case of transmission spin-orbit optical elements. This is illustrated by optical vortex generation from chiral liquid crystal droplets in the Bragg regime that unveils spin-orbit consequences of the droplet's curvature. Our results thus introduce a novel class of geometric phase elements-"Bragg-Berry" optical elements.

A simple and easily implemented design for an ultra-broadband variable phase compensator

We propose a novel design for a variable phase compensator (VPC) to improve bandwidth by minimizing the birefringent phase retardation (BPR) dispersion. Especially at the near-zero BPR point, the VPC has an extremely broad bandwidth. The VPC is based on only two kinds of birefringent crystals, and all its included components can be manufactured almost without need of dimension tolerance, which greatly simplifies its manufacture. According to our calculations, the VPC can keep its relative residual BPR within 2.4% with an ADP/KDP material combination, much smaller than that of the traditional quartz VPC for the tunable BPR from −180° to 180° in the spectral zone from 0.6 to 1.0 μm. This kind of VPC is suitable for accurately manipulating the polarization of broadband light pulses.

Arbitrary, direct and deterministic manipulation of vector beams via electrically-tuned q-plates.

Vectorial vortex light beams, also referred to as spirally polarized beams, are of particular interest since they can be exploited in several applications ranging from quantum communication to spectroscopy and microscopy. In particular, symmetric pairs of vector beams define two-dimensional spaces which are described as “hybrid Poincaré spheres” (HPS). While generation of vortex beams has been demonstrated by various techniques, their manipulation, in particular in order to obtain transformations describing curves entirely contained on a given HPS, is quite challenging, as it requires a simultaneous action on both polarization and orbital angular momentum degrees of freedom. Here, we demonstrate experimentally this kind of manipulation by exploiting electrically-tuned q-plates: an arbitrary transformation on the HPS can be obtained, by controlling two parameters of the q-plate, namely the initial optic axis orientation α0 and the uniform birefringent phase retardation δ. Upon varying such parameters, one can determine both the rotation axis and the rotation angle on the HPS, obtaining the desired state manipulation with high fidelity.

A broadband Soleil–Babinet compensator for ultrashort light pulses

This letter reports a novel design for a broadband Soleil–Babinet compensator including two pairs of optical wedges plus one plate. According to our birefringent dispersion compensation model, we can eliminate the first-order birefringent phase retardation (BPR) dispersion by using three different birefringent crystals. Our results show a Soleil–Babinet compensator based on a MgF2/ADP/KDP combination can work from 0° to 360° phase compensation with the maximal residual BPR less than 6° within the spectral region from 0.65 to 0.95 μm. The residual BPR of the compensator increases monotonically with the spectral deviation from the designed central wavelength, so our compensator is very suitable to be used for broadband laser pulses with most of their energies around the central wavelengths.

Design for the optical retardation in broadband zero-order half-wave plates

This paper presents a novel design for broadband zero-order half-wave plates to eliminate the first-order or up to second-order wavelength-dependent birefringent phase retardation (BPR) with 2 or 3 different birefringent materials. The residual BPRs of the plates increase monotonously with the wavelength deviation from a selected wavelength, so the plates are applicable to the broadband light pulses which gather most of the light energy around their central wavelengths. The model chooses the materials by the birefringent dispersion coefficient and evaluates the performances of the plates by the weighted average of the absolute value of residual BPR in order to emphasize the contributions of the incident spectral components whose possess higher energies.

Simultaneous Measurement of Phase Retardation and Fast-Axis Angle of Phase Retardation Plate

A phase retardation plate, such as a quarter-wave plate, is able to control the state of polarization. Thus, a precise simultaneous determination of phase delay between two eigen-polarization states and its fast-axis angle is essential to the performance of the phase retardation plate to control the state of polarization. Consequently, the measurement of the two-dimensional spatiotemporal distribution of phase retardation and the fast-axis angle become crucial when a large-area of phase retardation plate, such as that for a liquid crystal display, is characterized, due to the inhomogeneity of the retardation plate. In order to measure the linear birefringence parameters, phase retardation and fast-axis angle at the same time, a novel polarized optical heterodyne interferometer is developed, with which the parameters of a quarter-wave plate are successfully measured and verified. The features of this device are (1) a common-path configuration, (2) measurement independent of laser intensity, and (3) the capability of simultaneously determining the spatiotemporal distributions of phase retardation and fast-axis angle of a retardation plate.

Temperature and vibration insensitive fiber-optic current sensor

A robust interferometric fiber-optic current sensor with inherent temperature compensation of the Faraday effect is presented. Sensor configurations based on Sagnac and polarization-rotated reflection interferometers are considered. The sensing fiber is residing and thermally annealed in a coiled capillary of fused silica. The capillary is embedded in silicone within a ring-shaped housing. It is theoretically and experimentally shown that the temperature dependence of the birefringent fiber-optic phase retarders of the interferometers can be employed to balance the temperature dependence of the Faraday effect (0.7/spl times/10/sup -4///spl deg/C). Insensitivity of the sensor to temperature within 0.2% is demonstrated between -35/spl deg/C and 85/spl deg/C. The influence of the phase retarders on the linearity of the sensor is also addressed. Furthermore, the sensitivity to vibration of the two configurations at frequencies up to 500 Hz and accelerations up to 10 g is compared. High immunity of the reflective sensor to mechanical perturbations is verified.

Extended Jones matrix method and its application in the analysis of compensators for liquid crystal displays

We describe an extended Jones matrix method which is a powerful tool to treat the transmission of light through birefringent networks, where the incident angle of light and the optical axis of the birefringent media are arbitrary. The method is generalized to cover all dielectric media including uniaxial and biaxial crystals and gyrotropic materials that exhibit optical rotatory power and Faraday rotation. We then apply this method to investigate various birefringent optical thin films that can be used to improve the viewing angle characteristics and gray scale stability of conventional twisted nematic liquid crystal displays (TN-LCDs). The birefringent phase retardation films include negative uniaxial, positive uniaxial and biaxial films of various orientations. The results are presented and discussed.

Optics for element-resolved soft X-ray magneto-optical studies

The status of polarizing optical elements for the vacuum ultraviolet and soft X-ray range extending from roughly 50 to 2000 eV are reviewed, as are some of their emerging applications in magneto-optical studies utilizing synchrotron radiation. The optics include tunable linear polarizers and birefringent phase retarders based on multilayer interference structures, and circular polarizing filters based on magnetic circular dichroism. Magneto-optical capabilities enabled by these optical elements include measurement of Faraday and Kerr rotation spectra and hysteresis loops, and the conversion of linear to circular polarization and helicity switching. Circular polarizers combined with scanning zone plate microscopes yield magnetization contrast in transmission imaging. Examples using these capabilities to study polycrystalline Fe films and Fe/Cr multilayers are given. Resonant soft X-ray magneto-optical spectroscopies are especially relevant to obtaining an understanding of magnetism on a microscopic level in complex materials and nanostructures because their element-specific signals can be larger than in other spectral ranges. Combined with scattering and microscopy techniques these spectroscopies can provide depth sensitive and lateral spatial resolution on the nanometer scale.

Automated polarimeter–macroscope for optical mapping of birefringence, azimuths, and transmission in large area wafers. Part I. Theory of the measurement

A computer-controlled polarimeter–macroscope has been developed to measure birefringence (phase retardation), the principal azimuths and transmission in large area (up to 6 in. diameter) wafers. It consists of two HR-type linear polarizers which can be rotated simultaneously by a stepper motor versus an immobile wafer. The transmission axes of the polarizers can be set at either 90° or 0° (polariscopic mode) or at 45° (polarimetric mode). The ability of observing samples’ images in the polariscopic mode can be useful for, e.g., quick detection of macroscopic defects. In the polarimetric mode the arrangement is capable of collecting input data through a video frame grabber (VFG)/TV camera detecting system and calculate three maps as stated above within a fraction of a minute. In usual circumstances, using a VFG with 256 grey levels enables determination of birefringence with an error not greater than approximately 5×10−7, whereas errors of azimuths and transmission are of a fraction of a degree and of a percent, respectively. In this part of the work a theory of the method and a detailed error analysis are presented.

Anisotropy, birefringence, and optical phase retardation related to intersubband transitions in multiple quantum well structures

It is well known that the selection rules for intersubband transitions in quantum well structures require that the infrared light be polarized parallel to the growth direction. As a result, the induced intersubband susceptibility tensor becomes highly anisotropic and the crystal becomes birefringent. We have studied the effect of induced birefringence at the midinfrared range of the spectrum using a number of experimental techniques, including Fourier transform infrared absorption spectroscopy and optical phase retardation measurements using a tunable CO2 laser and a cross polarizer setup. We have observed that linearly polarized light becomes almost circularly polarized due to optical phase retardation between the ordinary and the extraordinary directions over a short optical path length of the order of 20 μm near the resonance (but not at the resonance). The real and the imaginary parts of the induced extraordinary refractive index were measured and have been found to be of the same order of magnitude. We also show that a solution of the Fresnel equation, modified to take into account both the imaginary and the real parts of the susceptibility tensor, is in good agreement with our experimental results.

Refractive index and birefringence measurements of the short-range order in the one-dimensional Heisenberg ferromagnet CsNiF3

Magnetic short-range order in the one-dimensional Heisenberg ferromagnet CsNiF3 has been investigated by linear magnetic birefringence and optical phase retardation measurements The short-range order was found to extend beyond 120K. The contributions of out-of-plane fluctuations and of the interchain interaction have been recognised. The values of the photoelastic coefficients and of the lattice dilatations are also reported.

MAGNETO-OPTICAL PROPERTIES OF A GREEN ROOM-TEMPERATURE FERROMAGNET FeF3

Ferric fluoride (FeF3) is a transparent green uniaxial weak ferromagnet (canted antiferromagnet) with a Curie temperature of 365 °K. FeF3 is far more transparent in the visible and uv than any other known material which has a spontaneous magnetic moment at room temperature. FeF3 at room temperature has 6 absorption bands between 7000 Å and the band edge which is at 2440 Å. There is a local absorption minimum of α = 4.4 cm−1 in the green at 5225 Å. The Faraday rotation is 180 °/cm at 5225 Å and increases to 1100 °/cm at 3000 Å. The birefringent phase retardation at 5200 Å is about 80 000 °/cm. The two indices of refraction are about 1.54 in the visible spectrum.