Detection Of Polarization State Research Articles

AFM-NSOM Nano-Polarimeter: Wide-ranging sensing device for synchronized scanning

This paper explores the use of an enhanced AFM-NSOM system tip as a nanoscale polarimeter. The tip consists of a tungsten-silicon conical photodetector modified with four differently-shaped subwavelength apertures, which enable the determination of incident light's four Stokes parameters and in turn its polarization state on the Poincaré sphere. The system is mounted on a standard Atomic Force Microscope (AFM) cantilever and can serve as a triple-mode scanning system, with complementary topography scanning, optical data analysis, and polarization state detection. The device was designed and simulated using the Comsol Multi-Physics software package, and initial steps toward fabrication were taken using the application of advanced nanotechnology tools to a commercial AFM probe. After a discussion of the advantages and drawbacks of drilled scanning tips vis-a-vis standard ones, the article presents the simulation and fabrication results of the nano-polarimeter tip.

Simultaneous detection of polarization states and wavefront by an angular variant micro-retarder-lens array.

We have demonstrated simultaneous detection of the polarization states and wavefront of light using a 7 × 7 array of angular variant micro-retarder-lenses. Manipulating the angular variant polarization with our optical element allows us to determine the two-dimensional distribution of polarization states. We have also proposed a calibration method for polarization measurements using our micro-retarder-lens array, allowing accurate detection of polarization states with an ellipticity of ± 0.01 and an azimuth of ± 1.0°. We made wavefront measurements using the micro-retarder-lens array, achieving a resolution of 25 nm. We conducted simultaneous detection of the polarization states and wavefront on four types of structured beam as samples. The results show that the two-dimensional distributions of the polarization states and wavefront for the four types of structured light are radially and azimuthally polarized beams, as well as left- and right-hand optical vortices. Our sensing technology has the potential to enhance our understanding of the nature of light in the fields of laser sciences, astrophysics, and even ophthalmology.

Ultracompact Metasurface for Simultaneous Detection of Polarization State and Orbital Angular Momentum

AbstractIn the field of optical communications and quantum informatics, polarization and orbital angular momentum (OAM) offer a promising way to expand the dimension of information. However, detecting the polarization state and topological charge of the OAM beam on‐chip way can be challenging. To address this, an ultracompact metasurface is proposed and demonstrated. The metasurface is composed of six polarization‐sensitive metalenses that occupy 60°annular sectors each and are capable of simultaneous polarization state and orbital angular momentum detection. The metasurface focuses the coaxial polarized vortex beam into six locations, and the foci displacement is related to the value of the topological charge. The corresponding polarization state can be obtained through the reconstructed Stokes parameter using the six focus light intensities. For proof‐of‐concept, an ultracompact metasurface operating at a wavelength of 1064 nm is fabricated, which exhibits exceptional polarization and orbital angular momentum recognition ability. The proposed metasurface possesses the merits of ultra‐compact size and simultaneously entire polarization state and orbital angular momentum identification capability, which may encourage the development of on‐chip optical communication systems.

Long distance distributed optical fiber vibration sensing and positioning technology based on loop transmission polarization detection

In this paper, a simple and low cost optical fiber sensing technology by using loop transmission polarization detection and cross-correlation algorithm for long distance vibration measurement is presented and investigated. Firstly, the influence mechanism of external disturbance on the polarization state of transmission light in sensing fiber is analyzed theoretically, and then the feasibility of the vibration sensing through polarization state detection is verified and corresponding experiments are carried out to evaluate the performance of the scheme. The results confirm that the proposed system can achieve a sensing distance of 200 km with a detection frequency ranging from 100 Hz to 100 kHz and a relative location error around 0.533%, meanwhile the influence of polarization-induced fading and trapped wave can also be avoided that provides a cost-effective solution for long distance disturbance monitoring.

Terahertz metasurface polarization detection employing vortex pattern recognition

The manipulation and detection of polarization states play a crucial role in the application of 6G terahertz communication. Nonetheless, the development of compact and versatile polarization detection devices capable of detecting arbitrary polarizations continues to be a challenging endeavor. Here, we demonstrate a terahertz polarization detection scheme by performing mode purity analysis and multidimensional analysis of the transmitted vortex field. The power of the proposed polarization recognition is verified by using three polarization trajectories, including linear polarizations, circular polarizations, and elliptical polarizations. Using the reconstructed complete polarization parameters, the detected polarization states are characterized using polarization ellipses, Poincaré sphere, and full-Stokes parameters. The experimental results validate the power of this scheme in polarization detection. This scheme holds promise for applications in polarization imaging and terahertz communication.

Detection of polarization state of a polarized light using azimuthally symmetric dye-doped liquid crystals

Detection of polarization state of a polarized light using azimuthally symmetric dye-doped liquid crystals (AS-DdLCs) is demonstrated. The first method is that the image of a polarized light with unknown polarization state after passing through the AS-DdLCs is captured by a charge-coupled device and transformed to a gray-level image, which is then analyzed by the designed program to identify the polarization state of the polarized light. The second method of comparing images using a database to identify the polarization state of an unknown polarized light is proposed. The techniques to increase detection accuracy of the two methods, and the comparison of the two methods are also discussed.

Identification of Railway Power Supply Voltage Sag Source Using Optical Fiber Voltage Sensor

With the construction of the smart grid and the continuous improvement of voltage levels, the traditional voltage sensor can no longer meet the development needs of the modern power system. There is an urgent need for a new high-quality voltage sensor to replace it. Aiming at the problems of complex structure, difficult adjustment, poor temperature stability, large optical power loss and inconvenient voltage introduction of the existing optical fiber voltage sensor, an optical fiber voltage sensor based on full polarization state detection without polarizer and analyzer is proposed. The sensor only contains three main components: Grin Lens, BGO crystal and total reflection mirror. It has few devices, simple structure and easy alignment. Moreover, the polarization state evolution and high voltage on the transmission line of Pockels effect of BGO crystal are analyzed. The voltage sag simulation model of the electrified railway is established. The sample data of different disturbance sources are obtained with the assistance of the designed optical fiber voltage sensor. S-transformation and Radial Basis Function (RBF) neural networks are introduced and combined with the prototype of electrified railway power quality detection and analysis device to identify voltage sag sources. The designed optical fiber voltage sensor is suspended. There is no electrode or grounding on the sensor, which saves expensive insulators and increases the sensor’s measuring range. The sensor has a good linear relationship in the power frequency AC voltage range of 0~10 kV at room temperature. It is proved that the design is effective. The working condition analysis of the actual railway power supply reveals that it can detect the voltage sag amplitude and disturbance time, and identify the type of voltage sag disturbance source.

Accurate polarization preparation and measurement using twisted nematic liquid crystals.

Generation of particular polarization states of light, encoding information in polarization degree of freedom, and efficient measurement of unknown polarization are the key tasks in optical metrology, optical communications, polarization-sensitive imaging, and photonic information processing. Liquid crystal devices have proved to be indispensable for these tasks, though their limited precision and the requirement of a custom design impose a limit of practical applicability. Here we report fast preparation and detection of polarization states with unprecedented accuracy using liquid-crystal cells extracted from common twisted nematic liquid-crystal displays. To verify the performance of the device we use it to prepare dozens of polarization states with average fidelity 0.999(1) and average angle deviation 0.5(3) deg. Using four-projection minimum tomography as well as six-projection Pauli measurement, we measure polarization states employing the reported device with the average fidelity of 0.999(1). Polarization measurement data are processed by the maximum likelihood method to reach a valid estimate of the polarization state. In addition to the application in classical polarimetry, we also employ the reported liquid-crystal device for full tomographic characterization of a three-mode Greenberger-Horne-Zeilinger entangled state produced by a photonic quantum processor.

Self-Powered Filterless On-Chip Full-Stokes Polarimeter

The detection of polarization states of light is essential in photonic and optoelectronic devices. Currently, the polarimeters are usually constructed with the help of waveplates or a comprehensive metasurface, which will inevitably increase the fabrication complexity and unnecessary energy loss. Here, we have successfully demonstrated a self-powered filterless on-chip full-Stokes polarimeter based on a single-layer MoS2/few-layer MoS2 homojunction. Combining the built-in electric field enhanced circular photogalvanic effect with the intrinsic optical anisotropy of MoS2 between in-plane and out-of-plane directions, the device is able to conveniently sense four Stokes parameters of incident light at zero bias without requiring an extra filtering layer and can function in the wavelength range of 650-690 nm with acceptable average errors. Besides, this homojunction device is easy to integrate with silicon-based chips and could have much smaller sizes than metasurface based polarimeters. Our study thus provides an excellent paradigm for high-performance on-chip filterless polarimeters.

Multifunctional metalens generation using bilayer all-dielectric metasurfaces.

Optical metasurfaces exhibit unprecedented ability in light field control due to their ability to locally change the phase, amplitude, and polarization of transmitted or reflected light. We propose a multifunctional metalens with dual working modes based on bilayer geometric phase elements consisting of low-loss phase change materials (Sb2Se3) and amorphous silicon (a-Si). In transmission mode, by changing the crystalline state of the Sb2Se3 scatterer, a bifocal metalens with an arbitrary intensity ratio at the telecommunication C-band is realized, and the total focusing efficiency of the bifocal metalens is as high as 78%. Also, at the resonance wavelength of the amorphous Sb2Se3 scatterer, the scatterer can be regarded as a half-wave plate in reflection mode. The multifunctional metalens can reversely converge incident light into a focal point with a focusing efficiency of up to 30%. The high focusing efficiency, dynamic reconfigurability, and dual working modes of the multifunctional metalens contribute to polarization state detection, optical imaging, and optical data storage. In addition, the bilayer geometric phase elements can be easily extended to multilayer, which significantly improves the capability of manipulating the incident light field.

VCSELs with On‐Facet Metasurfaces for Polarization State Generation and Detection

AbstractPolarization plays a critical role in optical systems that range from optical communications to imaging, lithography, metrology, and data storage. Thus, in systems that need to generate a certain polarization state, a light source (e.g., laser) is combined with polarization control elements such as polarizers, polarizing beam splitters, and waveplates. Similarly, in systems requiring polarization state detection, such elements are combined with photodetectors. There is currently a trend toward miniaturized optical systems. This motivates the question of how to achieve what may be argued as an ultimate level of miniaturization: a single chip that can both generate light with a prescribed polarization state and detect the polarization state of light impinging upon it. This paper demonstrates this via vertical cavity surface emitting lasers (VCSELs) with on‐facet metasurfaces. Two classes of devices are demonstrated. The first class uses high‐index dielectric metasurfaces (amorphous silicon nanofins), whereas the second class uses plasmonic metasurfaces (aluminum bilayer gratings). Each can operate as a laser (to generate) and as a photodetector (to detect) circularly or linearly polarized light.

椭圆偏振太赫兹辐射偏振态的单发测量

椭圆偏振太赫兹辐射偏振态的单发测量

Distributed measurement of polarization mode coupling in fiber ring based on P-OTDR complete polarization state detection.

Using a quaternion method, the polarization mode-coupling coefficient can be derived from three components of the Stokes vectors at three adjacent points along a fiber. A complete polarization optical time-domain reflectometry scheme for polarization mode coupling distributed measurement in polarization-maintaining fiber ring is proposed based on the above theoretical derivations. By comparing the measurement results of two opposite incident directions and two orthogonal polarization axes of polarization-maintaining fiber rings with different lengths, the feasibility and repeatability of the measurement scheme are verified experimentally with a positioning spatial resolution of 1 meter.

Wavelength encoded polarization measurements for simultaneous spectral and polarimetric characterization in near field

We report a scheme for polarization sensitive near field imaging of nanostructured samples by making use of broadband polarized near field illumination and detection of polarization states of scattered light by a spectrally encoded analyzer. The analyzer comprising a combination of polarizer, a multi-order waveplate and a broadband quarter waveplate allows analysis of the spectrally encoded polarization states of scattered light for characterization of the polarization properties of nano structures from a single image scan. The scheme was validated by measuring the near field polarization parameters of silver nanowires. The approach allows simultaneous measurement of polarization characteristics as well as spectral features of the nano materials.

基于全偏振态检测的悬挂式光纤电压传感器

Aiming at some problems of existing optical fiber voltage sensors,such as complex structure,adjustment difficulties,poor temperature stability,optical power loss and voltage introduced inconvenience,a new structure of suspended optical fiber voltage sensor based on all polarization state detection without polarizer and analyzer was proposed.The sensor only contained three main elements that are a self-focusing lens,a Bi4Ge3O12crystal and a total reflection mirror.For the fewer devices,the structrue is simple and it is easy to align.All polarization state detection system was described.It uses division-of-amplitude method and has fast response and simple algorithm.Formulas about polarization state,electric field and the measured voltage were calculated.Experiment of measuring the high voltage by suspending the sensor was demonstrated.The sensor in the experiment has no electrode and without ground,which eliminates the need for expensive insulators and increases the range of the sensor.The experiment results show that the sensor has a good linearity at room temperature in the range of 0~10kV AC voltage at power-frequency,which proves the feasibility of the structure.

Full-field detection of polarization state based on multiplexing digital holography

Based on digital holography recording system, it is proposed to use both polarization and angular multiplexing techniques to detect a polarization state. Reference beam is divided into two beams with orthogonal polarization directions and equal initial phases. And the beams interfere with the two orthogonal components of object wave respectively, which generates two holograms recorded in one frame. The use of angular multiplexing separates the two orthogonal components of object wave in the Fourier domain by respectively introducing carriers towards different directions. By numerical filtering, inverse Fourier transform and then diffraction calculation, complex amplitude of object wave can be obtained at different distances to the holograms. With the obtained complex amplitude, it is possible to work out both the Stokes parameters and Jones vector, which describe the polarization state of the object wave. The measuring of elliptical polarization state and the characterizing of polarization states at different locations on axis prove the validity of this real-time full-field detection method.

Expanded beam (macro-imaging) ellipsometry

Our aim was to make possible to use spectroscopic ellipsometry for mapping purposes during one measuring cycle (minimum one rotation period of polarizer or analyzer) on many sample points. Our new technique uses non-collimated (non-parallel, mostly diffuse) illumination with an angle of incidence sensitive pinhole camera detector system and it works as an unusual kind of imaging ellipsometry. Adding multicolour supplemets, it provides spectral (a few wavelengths on a 2D image or a full spectrum along a line) information from rapid measurements of many points on a large (several dm2) area. This technique can be expanded by upscaling the geometry (upscaling the dimensions of the instrument, and characteristic imaging parameters such as focal lengths, distances, etc.). The lateral resolution is limited by the minimum resolved-angle determined by the detector system, mainly by the diameter of the pinhole. (The diameter of the pinhole is a compromise between the light intensity and the lateral resolution.) Small-aperture (25mm diameter) polarizers are incorporated into both the polarization state generator (PSG) and polarization state detection (PSD) components of the instrument.The detection is almost without background because the pinhole serves as a filter against the scattered light. One rapid measuring cycle (less than 10 s) is enough to determine the polarization state at all the points inside the illuminated area. The collected data can be processed very fast (seconds) providing nearly real-time thicknesses and/or refractive index maps over many points of the sample surface even in the case of multilayer samples. The speed of the measuring system makes it suitable for using even on production lines. The necessary (in each sample-point different) angle-of-incidence and the mirror-effect calibration are made via well-known and optimized structures such as silicon/silicon-dioxide samples. The precision is suitable for detecting sub-nanometer thickness and a refractive index change of 0.01.The method can be used for mapping and quality control in the case of large area solar cell table production lines even in a vacuum chamber with 5–10mm lateral resolution.

Rapid Mueller matrix polarimetry based on parallelized polarization state generation and detection

We present rapid Mueller matrix polarimetry that can extract twelve Muller matrix elements from a single intensity image in real time and with high spatial resolution. This is achieved by parallelizing the respective polarization state generation and polarization state detection processes, which in existing polarimeters is performed sequentially. Parallelization of the polarization state generation process is accomplished through the use of vector beams, for which this work represents a new application domain. Polarization state detection is parallelized by uniquely combining a microscope/array detector setup with a specialized algorithm that simultaneously utilizes information from multiple spatial regions of the array detector. Simulated results applying this technique to two anisotropic samples including metamaterial yield material parameters that are consistent with those reported in the literature.

Experimental Setup for in Situ Investigation of Phase Changing Behavior in Phase-Change Random-Access Memory Medium by Microfocusing Nanosecond-Time-Resolved Ellipsometry

An ellipsometer with nanosecond time resolution has been proposed for the investigation of the phase change behavior of Ge2Sb2Te5 heated by electrical pulses of 20–100 ns in real time. This passive single-wavelength ellipsometer has a division-of-amplitude photopolarimeter (DOAP) configuration for polarization state detection to collect ellipsometric data in nanoseconds and consists of a microfocusing lens system to achieve a spot size of ∼15 µm.

Polarization Effects in Optical Coherence Tomography of Various Biological Tissues.

Polarization sensitive optical coherence tomography (PS-OCT) was used to obtain spatially resolved ex vivo images of polarization changes in skeletal muscle, bone, skin and brain. Through coherent detection of two orthogonal polarization states of the signal formed by interference of light reflected from the biological sample and a mirror in the reference arm of a Michelson interferometer, the depth resolved change in polarization was measured. Inasmuch as any fibrous structure will influence the polarization of light, PS-OCT is a potentially powerful technique investigating tissue structural properties. In addition, the effects of single polarization state detection on OCT image formation is demonstrated.