High-resolution Polarization Images Research Articles

Gate Voltage- and Bias Voltage-Tunable Staggered-Gap to Broken-Gap Transition Based on WSe2/Ta2NiSe5 Heterostructure for Multimode Optoelectronic Logic Gate.

Two-dimensional (2D) materials with superior properties exhibit tremendous potential in developing next-generation electronic and optoelectronic devices. Integrating various functions into one device is highly expected as that endows 2D materials great promise for more Moore and more-than-Moore device applications. Here, we construct a WSe2/Ta2NiSe5 heterostructure by stacking the p-type WSe2 and the n-type narrow gap Ta2NiSe5 with the aim to achieve a multifunction optoelectronic device. Owing to the large interface potential barrier, the heterostructure device reveals a prominent diode feature with a large rectify ratio (7.6 × 104) and a low dark current (10-12 A). Especially, gate voltage- and bias voltage-tunable staggered-gap to broken-gap transition is achieved on the heterostructure device, which enables gate voltage-tunable forward and reverse rectifying features. As results, the heterostructure device exhibits superior self-powered photodetection properties, including a high detectivity of 1.08 × 1010 Jones and a fast response time of 91 μs. Additionally, the intrinsic structural anisotropy of Ta2NiSe5 endows the heterostructure device with strong polarization-sensitive photodetection and high-resolution polarization imaging. Based on these characteristics, a multimode optoelectronic logic gate is realized on the heterostructure via synergistically modulating the light on/off, polarization angle, gate voltage, and bias voltage. This work shed light on the future development of constructing high-performance multifunctional optoelectronic devices.

A high-performance and self-powered polarization-sensitive photoelectrochemical-type Bi2O2Te photodetector based on a quasi-solid-state gel electrolyte.

Among the two-dimensional (2D) Bi2O2X (X = S, Se, and Te) series, Bi2O2Te has the smallest effective mass and the highest carrier mobility. However, Bi2O2Te has rarely been investigated, most likely due to the lack of feasible methods to synthesize 2D Bi2O2Te. Herein, 2D Bi2O2Te nanosheets are successfully synthesized by low-temperature oxidation of Bi2Te3 nanosheets synthesized using a solvothermal method. The performance of a quasi-solid-state photoelectrochemical-type (PEC-type) photodetector based on 2D Bi2O2Te nanosheets is systematically investigated. Remarkably, the device has a high responsivity of 20.5 mA W-1 (zero bias) and fast rise/fall times of 6/90 ms under 365 nm illumination, which is superior to the majority of PEC-type photodetectors based on bismuth-based compounds. More importantly, due to the strong anisotropy of 2D Bi2O2Te nanosheets, the device achieves a dichroic ratio as high as 52, which belongs to the state-of-the-art polarized photodetectors. Besides, the capacity of 2D Bi2O2Te for high-resolution polarization imaging is demonstrated. This work provides a promising strategy for the synthesis of 2D Bi2O2Te nanosheets to fabricate a high-performance and polarization-sensitive photodetector.

High-Resolution Metalens Imaging Polarimetry.

Imaging polarimeters find many critical applications in applications ranging from remote sensing to biological detection. Metasurfaces have been proposed as a compact approach for imaging polarimeters, but prior strategies suffer from low imaging resolution. Here, we propose an interleaved metalens configuration for polarization imaging where three-row metasurface units within a group individually interact with three pairs of orthogonal polarization channels. The optical paths between the object and adjacent three-row metasurfaces are nearly equal, allowing the construction of a metalens polarimeter with an unlimited numerical aperture (NA), which is beneficial for high-resolution polarization imaging. The metalens polarimeter fabricated by crystalline silicon nanostructures has a NA of 0.51 at 632.8 nm and achieves an imaging resolution of up to a 1.2-fold wavelength. Polarimetric microscopy experiments demonstrate that metalens polarimeters can realize high-resolution polarization imaging for various microscopic samples. This study offers a promising solution for high-resolution metasurface polarization imaging, with the potential for widespread applications.

Polarization image demosaicing and RGB image enhancement for a color polarization sparse focal plane array.

The color division of focal plane (DoFP) polarization sensor structure mostly uses Bayer filter and polarization filter superimposed on each other, which makes the polarization imaging unsatisfactory in terms of photon transmission rate and information fidelity. In order to obtain high-resolution polarization images and high-quality RGB images simultaneously, we simulate a sparse division of focal plane polarization sensor structure, and seek a sweet spot of the simultaneous distribution of the Bayer filter and the polarization filters to obtain both high-resolution polarization images and high-quality RGB images. In addition, From the perspective of sparse polarization sensor imaging, leaving aside the traditional idea of polarization intensity interpolation, we propose a new sparse Stokes vector completion method, in which the network structure avoids the introduction and amplification of noise during polarization information acquisition by mapping the S1 and S2 components directly. The sparsely polarimetric image demosaicing (Sparse-PDM) model is a progressive combined structure of RGB image artifact removal enhancement network and sparsely polarimetric image completion network, which aims to compensate sparsely polarimetric Stokes parameter images with the de-artifacts RGB image as a guide, thus achieving high-quality polarization information and RGB image acquisition. Qualitative and quantitative experimental results on both self-constructed and publicly available datasets prove the superiority of our method over state-of-the-art methods.

Helical polymers for dissymmetric circularly polarized light imaging.

Control of the spin angular momentum (SAM) carried in a photon provides a technologically attractive element for next-generation quantum networks and spintronics1-5. However, the weak optical activity and inhomogeneity of thin films from chiral molecular crystals result in high noise and uncertainty in SAM detection. Brittleness of thin molecular crystals represents a further problem for device integration and practical realization of chiroptical quantum devices6-10. Despite considerable successes with highly dissymmetric optical materials based on chiral nanostructures11-13, the problem of integration of nanochiral materials with optical device platforms remains acute14-16. Here we report a simple yet powerful method to fabricate chiroptical flexible layers via supramolecular helical ordering of conjugated polymer chains. Their multiscale chirality and optical activity can be varied across the broad spectral range by chiral templating with volatile enantiomers. After template removal, chromophores remain stacked in one-dimensional helical nanofibrils producing a homogeneous chiroptical layer with drastically enhanced polarization-dependent absorbance, leading to well-resolved detection and visualization of SAM. This study provides a direct path to scalable realization of on-chip detection of the spin degree of freedom of photons necessary for encoded quantum information processing and high-resolution polarization imaging.

Design and Experiment of High-Resolution Multispectral Polarization Imaging System

This paper addresses the objectives in a complex context: the polarization mathematical and physical model of the basic components of the target/background is constructed by simulation modeling. The image fusion experiment is carried out based on a two-dimensional wavelet transformation. A high-resolution polarization imaging instrument was developed, and static experiments were carried out with polarization, infrared, and visible cameras. The result shows that using polarization imaging detection technology to detect physical evidence targets in complex backgrounds can effectively improve target contrast. It can enrich the target information, improve image quality, and improve target detection accuracy.

Dynamic phase measurement of a transparent object by parallel phase-shifting digital holography with dual polarization imaging cameras

Measurement of surface shape and refractive index for moving transparent objects is critical in various fields. A parallel phase-shifting digital holography system that can record and reconstruct the phase information of moving transparent objects using two high-resolution polarization imaging cameras was presented. In the developed system, two polarization imaging cameras with 3.45 µm pixel pitch passed through the object in different directions. These two polarization imaging cameras were controlled by LabVIEW and worked synchronously. The proposed system can obtain the object's integral phase distributions in different directions, which is more effective for measuring an asymmetric object. In the experiment, the resolution of the system was confirmed by using a transmission-type test target. Besides, the dynamic phase measurement of an irregularly shaped transparent object was completed to verify the proposed system's effectiveness.

Comparative study of the influence of imaging resolution on linear retardance parameters derived from the Mueller matrix

Polarization imaging techniques are emerging tools to provide quantitative information of anisotropic structures, such as the density and orientation distribution of fibers in tissue samples. Recently, it is found that when using Mueller matrix polarimetry to obtain the structural features of tissue samples, some information can be revealed by relatively low-resolution polarization parameter images. Thus, to analyze what kinds of anisotropic optical and structural information contained in high-resolution polarization images are preserved in low-resolution ones, here we carry out a comparative study of the influence of imaging resolution on the Mueller matrix derived linear retardance parameters. We measure the microscopic Mueller matrix of human healthy breast duct tissues and ductal carcinoma in situ (DCIS) tissues, which have distinct typical fibrous structures, using objectives with different numerical aperture. Then we quantitatively compare a group of image texture feature parameters of the linear retardance parameters images under high and low imaging resolutions. The results demonstrate that the fibers density information contained in the texture features of linear retardance δ parameter image are preserved well with the decline of imaging resolution. While for the azimuthal orientation parameter θ which closely related to the spatial location, we still need high imaging resolution to obtain quantitative structural information. The study provides an important criterion to decide which information of fibrous structures can be extracted accurately using transmission Mueller matrix microscope with low numerical aperture objectives.

Highly Polarization-Sensitive, Broadband, Self-Powered Photodetector Based on Graphene/PdSe2/Germanium Heterojunction.

Polarization-sensitive photodetection in a broad spectrum range is highly desired due to the great significance in military and civilian applications. Palladium diselenide (PdSe2), a newly explored air-stable, group 10 two-dimensional (2D) noble metal dichalcogenide with a puckered pentagonal structure, holds promise for polarization-sensitive photodetection. Herein, we report a highly polarization-sensitive, broadband, self-powered photodetector based on graphene/PdSe2/germanium heterojunction. Owing to the enhanced light absorption of the mixed-dimensional van der Waals heterojunction and the effective carrier collection with graphene transparent electrode, the photodetector exhibits superior device performance in terms of a large photoresponsivity, a high specific detectivity, a fast response speed to follow nanosecond pulsed light signal, and a broadband photosensitivity ranging from deep ultraviolet (DUV) to mid-infrared (MIR). Significantly, highly polarization-sensitive broadband photodetection with an ultrahigh polarization sensitivity of 112.2 is achieved, which represents the best result for 2D layered material-based photodetectors. Further, we demonstrated the high-resolution polarization imaging based on the heterojunction device. This work reveals the great potential of 2D PdSe2 for high-performance, air-stable, and polarization-sensitive broadband photodetectors.

High-resolution multiband polarization epithelial tissue imaging method by sparse representation and fusion

Multiband polarization epithelial tissue imaging is an effective tool to measure tissue's birefringence and structure for quantitative pathology analysis. To discriminate the pathology accurately, high-resolution multiband polarization images are essential. But it is difficult to acquire high-resolution polarization images because of the limitations of imaging systems. The polarization image calculation process can be regarded as image fusion with fixed rules, and multiband polarization images are intrinsically sparse. In this paper, we propose a novel high-resolution multiband polarization image calculation method by utilizing the sparse representation and image fusion method. The multiband images are first represented in the sparse domain and we further introduce total-variation-regularization terms into the sparse representation framework. Then, polarization parameter images are calculated by simultaneous fusion and reconstruction. Higher quality multiband polarization images can be obtained through additional regularization constraint in the fusion process. Extensive experiments validate that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both peak signal-to-noise-ratio and visual perception.

The First Polarization Maps from the GMRT

We present the first set of polarimetric images made with the GMRT. We find that the instrumental polarization leakage at the GMRT varies with frequency. It is possible to calibrate these terms to better than 1% accuracy, making it feasible to study sources that are polarized at the few per cent level. We present 610 MHz polarization images of two extended FR-II radio galaxies, viz. 3C 79 and 3C 265. We present high resolution polarization images of these two sources and also find that the polarization fractions of the two sources as seen at the GMRT are consistent with those reported by Conway & Strom (1984).

AHubble Space TelescopePolarization Study of Dust in the η Carinae Homunculus

New high-resolution polarization images of the η Car Homunculus have been obtained with the Hubble Space Telescope (HST) at several wavelengths spanning the near-UV to the near-IR. With these images, taken with WFPC2 and NICMOS, we have been able to compare the polarization properties of the Homunculus at different wavelengths. We confirm that the Homunculus is primarily a reflection nebula and review the evidence that the inner region within 2'' of η Car has nonstellar hydrogen recombination emission. Additionally, we detect nebular [N II] emission in the inner 2'' region. We confirm that the large-scale morphology of the polarization appears to be independent of wavelength from the near-UV to the near-IR. The smooth images of polarization and the very structured images of intensity show that there is no correlation between the surface brightness and polarization. We examine the polarization percentages and vector angles of small-scale features in the Homunculus, such as the paddle, the skirt, the spot, and the southern ridge, to speculate on whether the features are composed of scattering particles similar to those in the lobes as a whole. We construct three-dimensional radiative transfer models of the Homunculus. The models have a hollow figure eight with a central light source. Radiation from the central source is Mie-scattered off dust grains in the figure eight into our line of sight. Patchy extinction lining the outer shell of the figure eight is used to explain surface brightness inhomogeneities, but the patchy extinction is not modeled. We find that a combination of small and large silicate dust grains reproduces the high polarization and independence with wavelength of the data much better than a model with a single distribution of standard ISM-type silicate dust grains. Finally, two different geometrical forms of the Homunculus from the literature were used in the models and found to produce very similar polarization features.

High-resolution polarization images of Crab Nebula with a charge-coupled device camera

Optical linear polarization of the Crab Nebula supernova remnant is presumed to be a good example of the astrophysical occurrence of synchrotron emission from relativistic electrons in a magnetic field1–3. However, there have been few attempts to map the spatial distribution of the polarization at the highest possible resolution and with high signal-to-noise ratio, although such observations contain information about the geometry and the small-scale structure of the magnetic field. We describe here observations of the Crab Nebula using a new charge coupled device (CCD) imaging/spectropolarimeter. Two large regions each 150 arc s across were observed with a seeing-limited spatial resolution of 1.5 arc s: the ‘eastern bay’ and the central wisps. The pulsar was included in both fields. In general, we find no evidence for substantial small-scale (1.5 arc s) structure in the projected magnetic field, but there are changes on scales of the order of 5 arc s which would be barely discernible by photographic methods. In addition, there is remarkable organization of the field over domains ranging in size from 10 to 30 arc s. The uncertainty about, the nebular polarization component near the pulsar is resolved. The presence or absence of small-scale structure in the field is important in understanding the energy transport mechanism for the relativistic electrons, and little is known about the connection between small polarization features and the remarkable filamentary structure in the nebula. Photographic maps2 had a resolution of only 5.25 arc s and rather limited polarimetric accuracy; more recent photoelectric measurements4 yielded 1 × 3 arc s resolution but only in a small patch. Instrumental technique is crucial.