Quarter-wave Retarder Research Articles

Negative dispersion retarder using two negative birefringence films.

The achromatic response and wide viewing angle for varying wavelength of incident light are of long waiting research to be utilized it for the display devices. Such response can be obtained by employing the retarder that exhibits negative birefringence and negative dispersion. In this paper, negative dispersion half-wave retarder and negative dispersion quarter-wave retarder have been demonstrated by optimizing the retardation and the angle between the extraordinary axes of polystyrene and poly-methylmethacrylate films. The optimum angles for half and quarter-wave retarders were found to be 40° and 70°, respectively for different retardation values of polystyrene and poly-methylmethacrylate films.

Reflective liquid crystal display for better productivity.

Most reflective LCDs so far proposed require a very thin cell gap of approximately 1.5μm to satisfy the quarter-wave retardation condition when used with a half-wave retardation film to obtain an acceptable broadband performance over the entire visible range. On the other hand, the inevitable difficulty associated with precise manufacturing of thin cell gap devices is likely to deteriorate the yield, thereby increasing the production cost. This paper proposes a reflective LCD with a larger cell thickness to achieve better productivity. The proposed reflective LCD consists of a tactically arranged stack of a half-wave retardation film, a quarter-wave retardation film, and a liquid-crystal (LC) layer whose optical performance has been confirmed both by simulation and experiment. The optimal optical configuration to obtain an excellent dark state in the visible range was determined by the Mueller matrices calculus as applied to each optical component. The simulated and experimental results showed that the proposed reflective LC structure has excellent electro-optical properties and is expected to be useful for the next generation LCD industry.

Experimental study of the polarization asymmetrical NOLM with adjustable switch power

This work presents a study of a nonlinear optical loop mirror (NOLM) based on polarization asymmetry. In contrast with the previously reported results where a quarter wave retarder was inserted to the loop to provide the polarization asymmetry, we used a wave retarder with variable retardation (VWR). We show that the use of the VWR allows easy adjustment of the switching power. We used in the experiment a NOLM made of 200-m length of standard SMF-28 fiber twisted at the rate of 6turn/m to mitigate linear birefringence. As source of pulses we used a mode-locked ring fiber laser that generates 0.7-ps pulses. A change of nonlinear transmission up to 10 times at the same input power was found in the experiments. The experimental results were corroborated with numerical simulation. The adjustment of the NOLM transmission makes it attractive for applications in optical switching devices or mode-locked fiber lasers.

A broadband silicon quarter-wave retarder for far-infrared spectroscopic circular dichroism

The high brightness, broad spectral coverage and pulsed characteristics of infrared synchrotron radiation enable time-resolved spectroscopy under throughput-limited optical systems, as can occur with the high-field magnet cryostat systems used to study electron dynamics and cyclotron resonance by far-infrared techniques. A natural extension for magnetospectroscopy is to sense circular dichroism, i.e. the difference in a material’s optical response for left and right circularly polarized light. A key component for spectroscopic circular dichroism is an achromatic 14 wave retarder functioning over the spectral range of interest. We report here the development of an in-line retarder using total internal reflection in high-resistivity silicon. We demonstrate its performance by distinguishing electronic excitations of differing handedness for GaAs in a magnetic field. This 14 wave retarder is expected to be useful for far-infrared spectroscopy of circular dichroism in many materials.

Quasi-periodic Fibonacci and periodic one-dimensional hypersonic phononic crystals of porous silicon: Experiment and simulation

A one-dimensional Fibonacci phononic crystal and a distributed Bragg reflector were constructed from porous silicon. The structures had the same number of layers and similar acoustic impedance mismatch, and were electrochemically etched in highly boron doped silicon wafers. The thickness of the individual layers in the stacks was approximately 2 μm. Both types of hypersonic band gap structure were studied by direct measurement of the transmittance of longitudinal acoustic waves in the 0.1–2.6 GHz range. Acoustic band gaps deeper than 50 dB were detected in both structures. The experimental results were compared with model calculations employing the transfer matrix method. The acoustic properties of periodic and quasi-periodic structures in which half-wave retarding bi-layers do not consist of two quarter-wave retarding layers are discussed. The strong correlation between width and depth of gaps in the transmission spectra is demonstrated. The dominant mechanisms of acoustic losses in porous multilayer structures are discussed. The elastic constants remain proportional over our range of porosity, and hence, the Grüneisen parameter is constant. This simplifies the expression for the porosity dependence of the Akhiezer damping.

Single shot interferometry using a two-interferogram phase shifting algorithm

Abstract An interferometer capable of retrieving the phase information in a single shot was implemented, the system was made by taking into account the double interferogram output obtained in a Mach Zehnder interferometer and then retrieving the phase information using a two-step algorithm already encountered in the literature. By controlling the polarization properties of the system, a new polarization phase shifting technique was implemented based upon the rotation of two quarter wave retarders placed in each of the arms of the interferometer. We present the analytical model taking into account the necessary conditions presented by the demodulation method. The configuration presented does not require micro-polarizer arrays or diffraction gratings presenting the advantage of avoiding the use of conventional polarizing filters to control the phase shift. Experimental results are presented.

Modeling and simulation of polarization errors in Sagnac fiber optic current sensor

Sagnac fiber optic current sensor (S-FOCS) is a kind of optical interferometer based on Sagnac structure, optical polarization states of sensing light wave in Sagnac fiber optic current sensor are limited. However, several factors induce optical polarization error, and non-ideal polarized light waves cause the interference signal crosstalk in sensor, including polarizer, quarter-wave retarder, splice angular, birefringence and so on. With these errors, linearly polarized light wave in PM fiber and circularly polarized light wave in sensing fiber become elliptically polarized light wave, then, nonreciprocal phase shift induced by magnetic field of the current is interrupted by wrong polarization state. To clarify characteristics of optical polarization error in fiber optic current sensor, we analyze the evolution process of random optical polarization state, linear optical polarization state and circular optical polarization state in Sagnac fiber optic current sensor by using Poincare sphere, then, build optical polarization error models by using Jones matrix. Based on models of polarization state in Sagnac fiber optic current sensor, we investigate the influence of several main error factors on optical polarization error characteristics theoretically, including extinction ratio in polarizer, phase delay in quarter-wave retarder, splice angular between quarter-wave retarder and polarization maintaining fiber. Finally, we simulate and quantify nonreciprocal phase shift to be detected in fiber optic current sensor related with optical polarization errors. In the end, we demonstrate S-FOCS in test. The results show that transfer matrix errors are induced by inaccurate polarization properties during polarization state conversion, then, the stability and accuracy of the S-FOCS are affected, and it is important to control the polarization properties at each step of the polarization state conversion precisely.

Novel achromatic single reflection quarter-wave retarder: Design and measurement

In this work, we present an achromatic quarter-wave retarder whose design is based upon the reflection properties of an isotropic-anisotropic interface. In theory, it is possible to obtain a π/2 phase shift by means of a total internal reflection at an isotropic-isotropic interface. However, in order to achieve such a phase shift, it is necessary to use a medium with a particularly high refractive index. We have previously shown that these phase shifts can be achieved by means of a total internal reflection in an isotropic-uniaxial interface, which allows the use of smaller refractive index media. By means of this property, we designed, built, and characterized a novel quarter-wave retarder that makes it possible to obtain circularly polarized light from a linear polarization state. We developed some guidelines that allowed us to obtain a device of competitive performance, low cost, and manageable manufacture.

Synchronization of Two Photoelastic Light Modulators to Obtain Müeller Matrix

We report a method for the temporal synchronization of two photoelastic light modulators. For synchronizing, we used the transistor-transistor logic output signals from each modulator, which contain the information on the light polarization. These signals were introduced in a phase-detector circuit, which provided the phase difference value between both modulators. Three optical devices were used to test the synchronization method proposed: a polarizer, a half-wave, and a quarter-wave retarder plate. The value of each of the elements of the Mueller matrix for these devices was obtained using the method of the 36 measurements. The results show a high correlation between the theoretical and experimental values obtained. The results are also in accordance with other values obtained by different methods reported in the literature. Errors calculated by the proposed method are approximately in the order of a thousandth. The advantages and disadvantages of the method are discussed.

9.1: Frontal Projection‐type Three‐dimensional Display with Enhanced Brightness Uniformity

AbstractA method to uniformize the brightness of elemental image for the frontal projection‐type three‐dimensional (3D) display is proposed. A frontal projection three‐dimensional display which is possible to realize glasses‐free 3D display by combining a polarizing screen with a front projector has been proposed recently. This method uses a quarter‐wave retarding film (QWRF) and a polarizer with slits, and makes the audience see different directional views. This structure can change the polarization state orthogonally, so the image from projector is partially blocked when the image is reflected and meets the films. However, in this method, the quality of the reconstructed 3D image could be degraded since the light intensity at the barrier‐free regions of parallax barrier polarizer is brighter than that at the parallax barrier polarizer. We proposed two methods to relieve this difference, a parallax barrier rearrangement method and gray level compensation of illumination. By adopting two methods, we anticipate that the quality of reconstructed 3D image can be enhanced because of brightness uniformity in directional‐view images in the frontal projection‐type 3D display method.

Focus on photonics and biomedical optics

Focus on photonics and biomedical optics

Prism-type retroreflector of stable quarterwave retardance over extended spectral ranges

The retardance introduced by a prism-type retroreflector depends on the refractive index of the prism material corresponding to the wavelength of the incident radiation and the values of the internal reflection angles. In normal-incidence devices (the external angle of incidence i=0°), the reflection angles θ are of fixed values and the retardance varies with the refractive index n. In this work, an oblique-incidence (i≠0), 3-reflection quarterwave retroreflector is presented which provides extreme stability of the retardance over extended spectral ranges. Between n=1.59 and n=1.73, the maximum deviation of the retardance from 90° is 0.1°. The device is suitable for use with laser beams.

Multi-twist retarders: broadband retardation control using self-aligning reactive liquid crystal layers

We report on a family of complex birefringent elements, called Multi-Twist Retarders (MTRs), which offer remarkably effective control of broadband polarization transformation. MTRs consist of two or more twisted liquid crystal (LC) layers on a single substrate and with a single alignment layer. Importantly, subsequent LC layers are aligned directly by prior layers, allowing simple fabrication, achieving automatic layer registration, and resulting in a monolithic film with a continuously varying optic axis. In this work, we employ a numerical design method and focus on achromatic quarter- and half-wave MTRs. In just two or three layers, these have bandwidths and general behavior that matches or exceeds all traditional approaches using multiple homogenous retarders. We validate the concept by fabricating several quarter-wave retarders using a commercial polymerizeable LC, and show excellent achromaticity across bandwidths of 450-650 nm and 400-800 nm. Due to their simple fabrication and many degrees of freedom, MTRs are especially well suited for patterned achromatic retarders, and can easily achieve large bandwidth and/or low-variation of retardation within visible through infrared wavelengths.

Variable ultrabroadband and narrowband composite polarization retarders

We propose and experimentally demonstrate novel types of composite sequences of half-wave and quarter-wave polarization retarders, permitting operation at either ultrabroad spectral bandwidth or narrow bandwidth. The retarders are composed of stacked standard half-wave retarders and quarter-wave retarders of equal thickness. To our knowledge, these home-built devices outperform all commercially available compound retarders, made of several birefringent materials.

A frontal projection-type three-dimensional display

In a typical auto-stereoscopic three-dimensional display, the parallax barrier or lenticular lens is located in front of the display device. However, in a projection-type auto-stereoscopic display, such optical components make it difficult to display elemental images on the screen or to reconstruct a three-dimensional image, even though a projection-type display has many advantages. Therefore, it is necessary to use a rear projection technique in a projection-type auto-stereoscopic display, despite the fact that this is an inefficient use of space. We propose here a frontal projection-type auto-stereoscopic display by using a polarizer and a quarter-wave retarding film. Since the proposed method uses a frontal projection scheme and passive polarizing components, it has the advantage of being both space saving and cost effective. This is the first report that describes a frontal projection-type auto-stereoscopic display based on a parallax barrier and integral imaging by using a projector. Experimental results that support the proposed method are provided.

Achromatic quarter-wave plate using crystalline quartz

Achromatic wave plates are ideal components for use with tunable and multiline laser systems, broadband sources, and in astronomical instrumentation. The present study deals with the design and characteristics of two different quarter-wave achromatic retarders in the 500-700 nm range, using a cascaded system of two birefringent plates. The first of these shows a variation of less than ±0.5°, whereas the second system shows a variation of ±4° where the azimuth remains constant. Finally, a comparison between the two systems is made. The succinct and simple Jones matrix formalism has been used to derive the general expression for the equivalent retardation and azimuth of the combinations. It appears that the proposed arrangement has the promise of producing good achromatic combinations.

Ultrathin Reflective Flexible Liquid Crystal Display Film

In this investigation, we present a thin reflective liquid crystal film with a mixed-mode twisted nematic mode. A low-temperature alignment process is used to obtain good orientation of the liquid crystal molecules. A microcell process is utilized to maintain a uniform cell gap of the flexible display under various bending conditions. To simplify the structure of a flexible mixed-mode twisted nematic liquid crystal display film, a layer of Zeonor optical plastic material is used in place of conventional plastic substrates; this material exhibits quarter wave retardation. The ultrathin device exhibits good cell gap uniformity, a high reflectivity of 35%, and a short response time of 6.67 ms.

Two-component gadget for transforming any two nonorthogonal polarization states into one another

We present an algorithm for transforming an arbitrary input polarization state into a nonorthogonal but otherwise arbitrary output polarization state, by using two quarter-wave retarders. Such an array reduces the number of retarders employed in the well-known Simon–Mukunda gadget, which consists of one half-wave and two quarter-wave retarders. The latter was designed to realize arbitrary SU(2) transformations on qubits. The gadget presented here accomplishes a related task, allowing to transforming an input qubit into a target qubit, by choosing a particular SU(2) transformation that is realizable with two quarter-wave plates.

Contrast‐enhanced wide‐angle high‐speed polarization modulator for active‐retarder 3‐D displays

Abstract— A contrast‐enhanced wide‐angle high‐speed polarization modulator for active‐retarder 3‐D displays is proposed. By using a double liquid‐crystal‐cell structure together with a dedicated driving scheme and an external quarter‐wave retarder, a high‐performance modulator can be realized, resulting in minimized brightness loss and low cross‐talk levels in fast‐refresh time‐multiplexed 3‐D displays.

Orientation of a bacteriorhodopsin thin film deposited by dip coating technique and its chiral SHG as studied by SHG interference technique

We show that by observing SHG interference bR thin films prepared by a simple dip coating technique have a polar orientation with C∞ symmetry. The SHG interference measurements were performed under various input and output polarization combinations at different incident angles or under the rotation of the quarter-wave retardation plate at specific incident angles. The interference patterns provide us with insight into the characteristics of non-vanishing nonlinear optical coefficients including chiral components. Abundant information can be obtained by observing SHG interference by using two chiral SH active films.