Tootfinder

RFI Removal from SAR Imagery via Sparse Parametric Estimation of LFM Interferences
Dehui Yang, Feng Xi, Qihao Cao, Huizhang Yang
https://arxiv.org/abs/2509.18809 https://…

from my link log —
Synthetic aperture radar autofocus and calibration.
https://hforsten.com/synthetic-aperture-radar-autofocus-and-calibration.html
saved 2025-10-11

Synthetic aperture radar autofocus and calibration
3D trajectory position error estimation autofocus, antenna pattern normalization, and polarimetric calibration for drone mounted SAR radar.

This guy made a Synthetic Aperture Radar (i.e. a radar that gives you camera-like pictures) mounted on a drone. Scroll to the bottom for actual sample pictures and a movie. Lots of tech detail and open-source designs and software.
https://hforsten.com/synthetic-apertur

Interesting to so easily see the quite aggressive radar/jamming near key Russian sites on European Space Agency's Synthetic-Aperture Radar imagery

Copernicus Browser
Search, visualise and download Sentinel satellite imagery

Spatial Signal Focusing and Noise Suppression for Direction-of-Arrival Estimation in Large-Aperture 2D Arrays under Demanding Conditions
Xuyao Deng, Yong Dou, Kele Xu
https://arxiv.org/abs/2510.10923

Spatial Signal Focusing and Noise Suppression for Direction-of-Arrival Estimation in Large-Aperture 2D Arrays under Demanding Conditions
Direction-of-Arrival (DOA) estimation in sensor arrays faces limitations under demanding conditions, including low signal-to-noise ratio, single-snapshot scenarios, coherent sources, and unknown source counts. Conventional beamforming suffers from sidelobe interference, adaptive methods (e.g., MVDR) and subspace algorithms (e.g., MUSIC) degrade with limited snapshots or coherent signals, while sparse-recovery approaches (e.g., L1-SVD) incur high computational complexity for large arrays. In thi…

Novel UWB Synthetic Aperture Radar Imaging for Mobile Robot Mapping
Charith Premachandra, U-Xuan Tan
https://arxiv.org/abs/2510.02874 https://arxiv.org/pdf…

Novel UWB Synthetic Aperture Radar Imaging for Mobile Robot Mapping
Traditional exteroceptive sensors in mobile robots, such as LiDARs and cameras often struggle to perceive the environment in poor visibility conditions. Recently, radar technologies, such as ultra-wideband (UWB) have emerged as potential alternatives due to their ability to see through adverse environmental conditions (e.g. dust, smoke and rain). However, due to the small apertures with low directivity, the UWB radars cannot reconstruct a detailed image of its field of view (FOV) using a single…

Snapshot Synthetic Aperture Imaging with Boiling Speckle
Janith B. Senanayaka, Christopher A. Metzler
https://arxiv.org/abs/2509.21682 https://arxiv.org/pd…

Snapshot Synthetic Aperture Imaging with Boiling Speckle
Light-based synthetic aperture (SA) imaging methods, such as Fourier Ptychography, have brought breakthrough high-resolution wide-field-of-view imaging capabilities to microscopy. While these technologies promise similar improvements in long-range imaging applications, macroscale light-based SA imaging is significantly more challenging. In this work, we first demonstrate that speckle noise is particularly problematic for light-based SA systems. Specifically, we prove that it is fundamentally im…

Virtual Reality Alters Perceived Functional Body Size
Xiaoye Michael Wang, Ali Mazalek, Catherine M. Sabiston, Timothy N. Welsh
https://arxiv.org/abs/2510.00824 https://

Virtual Reality Alters Perceived Functional Body Size
Virtual reality (VR) introduces sensory perturbations that may impact perception and action. The current study was designed to investigate how immersive VR presented through a head-mounted display (HMD) affects perceived functional body size using a passable aperture paradigm. Participants (n=60) performed an action task (sidle through apertures) and a perception task (adjust aperture width until passable without contact) in both physical, unmediated reality (UR) and VR. Results revealed signif…

The double neutron star PSR J1946 2052 I. Masses and tests of general relativity
Lingqi Meng, Paulo C. C. Freire, Kevin Stovall, Norbert Wex, Xueli Miao, Weiwei Zhu, Michael Kramer, James M. Cordes, Huanchen Hu, Jinchen Jiang, Emilie Parent, Lijing Shao, Ingrid H. Stairs, Mengyao Xue, Adam Brazier, Fernando Camilo, David J. Champion, Shami Chatterjee, Fronefield Crawford, Ziyao Fang, Qiuyang Fu, Yanjun Guo, Jason W. T. Hessels, Maura MacLaughlin, Chenchen Miao, Jiarui Niu, Ziwei Wu, Ju…

The double neutron star PSR J1946+2052 I. Masses and tests of general relativity
We conducted high-precision timing of PSR J1946+2052 to determine the masses of the two neutron stars in the system, test general relativity (GR) and assessed the system's potential for future measurement of the moment of inertia of the pulsar. We analysed seven years of timing data from the Arecibo 305-m radio telescope, the Green Bank Telescope (GBT), and the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The data processing accounted for dispersion measure variations and relat…

A roadmap to cosmological parameter analysis with third-order shear statistics IV. Analytic cross-covariance between second- and third-order aperture masses
Niek Wielders, Laila Linke, Pierre A. Burger, Sven Heydenreich, Lucas Porth, Peter Schneider
https://arxiv.org/abs/2509.20443

A roadmap to cosmological parameter analysis with third-order shear statistics IV. Analytic cross-covariance between second- and third-order aperture masses
Weak gravitational lensing is a powerful probe of cosmology, with second-order shear statistics commonly used to constrain parameters such as the matter density $Ω_\mathrm{m}$ and the clustering amplitude $S_8$. However, parameter degeneracies remain and can be reduced by including higher-order statistics such as the third-order aperture mass. To jointly analyse second- and third-order statistics, an accurate model of their cross-covariance is essential. We derive and validate a non-tomographi…

AMIGO: a Data-Driven Calibration of the JWST Interferometer
Louis Desdoigts, Benjamin Pope, Max Charles, Peter Tuthill, Dori Blakely, Doug Johnstone, Shrishmoy Ray, Anand Sivaramakrishnan, Jens Kammerer, Deepashri Thatte, Rachel Cooper
https://arxiv.org/abs/2510.09806

AMIGO: a Data-Driven Calibration of the JWST Interferometer
The James Webb Space Telescope (JWST) hosts a non-redundant Aperture Masking Interferometer (AMI) in its Near Infrared Imager and Slitless Spectrograph (NIRISS) instrument, providing the only dedicated interferometric facility aboard - magnitudes more precise than any interferometric experiment previously flown. However, the performance of AMI (and other high resolution approaches such as kernel phase) in recovery of structure at high contrasts has not met design expectations. A major contribut…

The optical photometric variability of Herbig Ae/Be stars from TESS
Ann Marie Cody, Lynne A. Hillenbrand, Shreya Chandragiri, Marvin Morgan
https://arxiv.org/abs/2510.08633 http…

The optical photometric variability of Herbig Ae/Be stars from TESS
We have carried out a photometric time domain study of 188 intermediate-mass young stars observed in Full Frame Image mode with the TESS satellite over the first 3.3 years of its mission. The majority of these targets are classified as Herbig Ae/Be stars (HAeBes). All were monitored at optical wavelengths for at least one 27-day TESS sector, with many having multiple sectors of data. From a custom aperture photometry pipeline, we produced light curves and analyzed the variability therein, as a …

Reanalysis of the eclipses of LHS 1140 c: No evidence of an atmosphere and implications for the internal structure of the planet
Alexandra Rochon, \'Etienne Artigau, Drew Weisserman, Lisa Dang, Ren\'e Doyon, Charles Cadieux, Ryan Cloutier
https://arxiv.org/abs/2510.11397

Reanalysis of the eclipses of LHS 1140 c: No evidence of an atmosphere and implications for the internal structure of the planet
We present the reanalysis of three 15 micron JWST/MIRI secondary eclipses of LHS 1140 c, a warm super-Earth (R$_{\rm{p}}$ = 1.272 R$_{\oplus}$) in a 3.78-day orbit around an M4.5 dwarf. We present a novel method for data reduction that leverages spatial derivatives of the point-spread function and compare it to widely used aperture photometry. Both methods yield eclipse depth consistent within 1 sigma of the values reported in the literature. We measure an eclipse depth of 271$^{+31}_{-30}$ ppm…

Joint DOA and Attitude Sensing Based on Tri-Polarized Continuous Aperture Array
Haonan Si, Zhaolin Wang, Xiansheng Guo, Jin Zhang, Yuanwei Liu
https://arxiv.org/abs/2510.02029 h…

Joint DOA and Attitude Sensing Based on Tri-Polarized Continuous Aperture Array
This paper investigates joint direction-of-arrival (DOA) and attitude sensing using tri-polarized continuous aperture arrays (CAPAs). By employing electromagnetic (EM) information theory, the spatially continuous received signals in tri-polarized CAPA are modeled, thereby enabling accurate DOA and attitude estimation. To facilitate subspace decomposition for continuous operators, an equivalent continuous-discrete transformation technique is developed. Moreover, both self- and cross-covariances …

Unlocking AGN Variability with Custom ZTF Photometry for High-Fidelity Light Curves and Robust Selection
P. Ar\'evalo (U. de Valpara\'iso, Chile), P. S\'anchez-S\'aez (ESO, Garching), B. Sotomayor (ESO, Garching), P. Lira (U. de Chile), F. E. Bauer (U. de Tarapac\'a, Chile), S. R\'ios (U. de Chile)
https://arxiv.org…

Unlocking AGN Variability with Custom ZTF Photometry for High-Fidelity Light Curves and Robust Selection
(Abridged)We explore the potential of optical variability selection methods to identify AGN, including those challenging to detect with conventional techniques. Using the unprecedented combination of depth, sky coverage, and cadence of the ZTF survey, we target even starlight-dominated AGN, known for their redder colours, weaker variability signals, and difficult nuclear photometry due to their resolved hosts. We perform aperture photometry on ZTF reference-subtracted images for 40 million sour…

Image reconstruction with the JWST Interferometer
Max Charles, Louis Desdoigts, Benjamin Pope, Peter Tuthill, Dori Blakely, Doug Johnstone, Shrishmoy Ray, K. E. Saavik Ford, Barry McKernan, Anand Sivaramakrishnan
https://arxiv.org/abs/2510.10924

Image reconstruction with the JWST Interferometer
Flying on board the James Webb Space Telescope (JWST) above Earth's turbulent atmosphere, the Aperture Masking Interferometer (AMI) on the NIRISS instrument is the highest-resolution infrared interferometer ever placed in space. However, its performance was found to be limited by non-linear detector systematics, particularly charge migration - or the Brighter-Fatter Effect. Conventional interferometric Fourier observables are degraded by non-linear transformations in the image plane, with the c…

On Hardy spaces, univalent functions and the second coefficient
Martin Chuaqui, Iason Efraimidis, Rodrigo Hern\'andez
https://arxiv.org/abs/2510.05395 https://

On Hardy spaces, univalent functions and the second coefficient
We consider normalized univalent functions with prescribed second Taylor coefficient $a_2$. For convex functions $f$ we study the Hardy spaces to which $f$ and $f'$ belong, refining in particular on a theorem of Eenigenburg and Keogh, and give a sharp asymptotic estimate and an explicit uniform bound for their coefficients. Relating the lower order of a convex function to the angle at infinity of its range we deduce that its range lies always in some sector of aperture $|a_2|π$. We g…

Effects of Wall Roughness on Coupled Flow and Heat Transport in Fractured Media
Alessandro Lenci, Yves M\'eheust, Maria Klepikova, Vittorio Di Federico, Daniel M. Tartakovsky
https://arxiv.org/abs/2510.07294

Effects of Wall Roughness on Coupled Flow and Heat Transport in Fractured Media
Heat transfer in fractured media is governed by the interplay between advective transport along rough-walled fractures and conductive transport, both within the fractures and in the surrounding low-permeability matrix. Flow localization induced by aperture heterogeneity, combined with matrix conduction, gives rise to anomalous thermal behavior. To capture these effects, we develop a stochastic modeling framework that couples a time-domain random walk (TDRW) representation of advective and condu…

Multiplexed back focal plane imaging with on-chip integrated microlens array
Magdalena Furman, Marcin Muszy\'nski, Przemys{\l}aw Oliwa, {\L}ukasz Zinkiewicz, Aleksander Bogucki, Jacek Szczytko, Piotr Wasylczyk, Wojciech Pacuski, Mateusz Kr\'ol, Barbara Pi\k{e}tka
https://arxiv.org/abs/2510.09348

Multiplexed back focal plane imaging with on-chip integrated microlens array
On-chip optical architectures that enable angle-resolved spectroscopy are essential for advancing photonic platforms towards low-volume, scalable, and cryo-compatible devices. Here, we introduce spatially resolved momentum-space imaging using arrays of 3D-printed microlenses directly integrated onto semiconductor optical microcavities. Each microlens functions as an independent optical element with a high numerical aperture (approx. 0.95), enabling parallel back focal plane imaging across, in o…

Control Requirements for Robust Beamforming in Multi-Satellite Systems
Diego Tuzi, Thomas Delamotte, Andreas Knopp
https://arxiv.org/abs/2510.11465 https://

Control Requirements for Robust Beamforming in Multi-Satellite Systems
This work investigates the impact of position and attitude perturbations on the beamforming performance of multi-satellite systems. The system under analysis is a formation of small satellites equipped with direct radiating arrays that synthesise a large virtual antenna aperture. The results show that performance is highly sensitive to the considered perturbations. However, by incorporating position and attitude information into the beamforming process, nominal performance can be effectively re…

Spectral Properties of Anomalous Microwave Emission in 144 Galactic Clouds
Roke Cepeda-Arroita, J. A. Rubi\~no-Mart\'in, R. T. G\'enova-Santos, C. Dickinson, S. E. Harper, F. Poidevin, M. W. Peel, R. Rebolo, D. Adak, A. Almeida, K. Aryan, R. B. Barreiro, F. J. Casas, J. M. Casas, J. Chluba, M. Fern\'andez-Torreiro, D. Herranz, G. A. Hoerning, Michael E. Jones, J. Leech, E. Mart\'inez-Gonz\'alez, T. J. Pearson, Angela C. Taylor, P. Vielva, R. A. Watson, Z. Zhang

Spectral Properties of Anomalous Microwave Emission in 144 Galactic Clouds
Anomalous Microwave Emission (AME) is a diffuse microwave component thought to arise from spinning dust grains, yet remains poorly understood. We analyze AME in 144 Galactic clouds by combining low-frequency maps from S-PASS (2.3 GHz), C-BASS (4.76 GHz), and QUIJOTE (10-20 GHz) with 21 ancillary maps. Using aperture photometry and parametric SED fitting via MCMC methods without informative priors, we measure AME emissivity, peak frequency, and spectral width. We achieve peak frequency constrain…

Fifty Years of SAR Automatic Target Recognition: The Road Forward
Jie Zhou, Yongxiang Liu, Li Liu, Weijie Li, Bowen Peng, Yafei Song, Gangyao Kuang, Xiang Li
https://arxiv.org/abs/2509.22159

Fifty Years of SAR Automatic Target Recognition: The Road Forward
This paper provides the first comprehensive review of fifty years of synthetic aperture radar automatic target recognition (SAR ATR) development, tracing its evolution from inception to the present day. Central to our analysis is the inheritance and refinement of traditional methods, such as statistical modeling, scattering center analysis, and feature engineering, within modern deep learning frameworks. The survey clearly distinguishes long-standing challenges that have been substantially miti…

Solar Low Energy X-ray Spectrometer on board Aditya-L1: Ground Calibration and In-flight Performance
Abhilash R. Sarwade, Ankur Kushwaha, M. C. Ramadevi, Monoj Bug, Kiran Lakshmipathaiah, Smrati Verma, Vaishali Sharan, K. Sankarasubramanian
https://arxiv.org/abs/2509.26292

Solar Low Energy X-ray Spectrometer on board Aditya-L1: Ground Calibration and In-flight Performance
The Solar Low-Energy X-ray Spectrometer (SoLEXS) on board India's Aditya-L1 mission was launched on 2 September 2023 and commenced solar observations on 13 December 2023 following successful aperture cover deployment. Operating from the Sun-Earth L1 Lagrange point, SoLEXS has been providing continuous Sun-as-a-star soft X-ray spectroscopy across 2-22 keV with 170 eV resolution at 5.9 keV and 1-second temporal cadence since 6 January 2024. The instrument employs two Silicon Drift Detectors with …

The impact of the point spread function fitting radius on photometric uncertainty based on the Fisher information matrix
Sebastian Espinosa, Mario L. Vicu\~na, Rene A. Mendez, Jorge F. Silva, Marcos Orchard
https://arxiv.org/abs/2509.20613

The impact of the point spread function fitting radius on photometric uncertainty based on the Fisher information matrix
In point spread function (PSF) photometry, the selection of the fitting aperture radius plays a critical role in determining the precision of flux and background estimations. Traditional methods often rely on maximizing the signal-to-noise ratio (S/N) as a criterion for aperture selection. However, S/N-based approaches do not necessarily provide the optimal precision for joint estimation problems as they do not account for the statistical limits imposed by the Fisher information in the context …

Crosslisted article(s) found for stat.AP. https://arxiv.org/list/stat.AP/new
[1/1]:
- Scalable deep fusion of spaceborne lidar and synthetic aperture radar for global forest structura...
Tiago de Conto, John Armston, Ralph Dubayah

4D Computational Ultrasound Imaging of Carotid Artery Flow
Yuyang Hu, Michael Brown, Didem Dogan, Mah\'e Bulot, Maxime Cheppe, Guillaume Ferin, Geert Leus, Antonius F. W. van der Steen, Pieter Kruizinga, Johannes G. Bosch
https://arxiv.org/abs/2509.20963

4D Computational Ultrasound Imaging of Carotid Artery Flow
Computational ultrasound imaging (cUSi) with few elements and spatial field encoding can provide high-resolution volumetric B-mode imaging. In this work, we extend its application to 4D carotid artery (CA) flow imaging using a custom large-aperture 240-element matrix probe. We implemented a frequency band-based matched filtering strategy that balances resolution and contrast. The system's inherent imaging capabilities were evaluated and validated in flow phantom and human CA experiments. In the…

Diffraction-limited operation of micro-metalenses: fundamental bounds and designed rules for pixel integration
Nicolas Kossowski, Christina Kyrou, R\'emi Colom, Pierre-Marie Coulon, Virginie Br\"andli, Jean-Luc Reverchon, Samira Khadir, Patrice Genevet
https://arxiv.org/abs/2510.04154

Diffraction-limited operation of micro-metalenses: fundamental bounds and designed rules for pixel integration
Metasurfaces provide a compact, flexible, and reliable solution for controlling the wavefront of light. In imaging systems, micro-lens arrays are integrated with pixel matrices to reduce optical crosstalk, enhance photon collection efficiency, and improve spatial resolution. However, as the aperture size of the photonic devices decreases, fundamental limitations associated with diffraction emerge. Here, we theoretically analyze and experimentally demonstrate that these constraints also affect t…

The IEEE Signal Processing Society's Leading Role in Developing Standards for Computational Imaging and Sensing: Part II
Andreas Bathelt, Benjamin Deutschmann, Hyeon Seok Rou, Kuranage Roche Rayan Ranasinghe, Giuseppe Thadeu Freitas de Abreu, Peter Vouras
https://arxiv.org/abs/2510.04913

The IEEE Signal Processing Society's Leading Role in Developing Standards for Computational Imaging and Sensing: Part II
In every imaging or sensing application, the physical hardware creates constraints that must be overcome or they limit system performance. Techniques that leverage additional degrees of freedom can effectively extend performance beyond the inherent physical capabilities of the hardware. An example includes synchronizing distributed sensors so as to synthesize a larger aperture for remote sensing applications. An additional example is integrating the communication and sensing functions in a wire…

Millimeter-Wavelength Dual-Polarized Lens-Absorber-Coupled Ti/Al Kinetic Inductance Detectors
Alejandro Pascual Laguna, Victor Rollano, Aimar Najarro-Fiandra, David Rodriguez, Maria T. Magaz, Daniel Granados, Alicia Gomez
https://arxiv.org/abs/2510.02971

Millimeter-Wavelength Dual-Polarized Lens-Absorber-Coupled Ti/Al Kinetic Inductance Detectors
This work presents Ti/Al bi-layer Microwave Kinetic Inductance Detectors (MKIDs) based on lens-coupled spiral absorbers as the quasi-optical coupling mechanism for millimeter-wavelength radiation detection. From simulations, the lens-coupled absorbers provide a 70% lens aperture efficiency in both polarizations over an octave band with a spiral array absorber and over 10% relative bandwidth with a single spiral. We have fabricated and measured two devices with bare Ti/Al MKIDs: a 3x3 cm chip wi…

Designing Coherent Optical Environment for Dynamic Optical Manipulation with a Simple Control Beam
Xiaoshu Zhao, Xu Yuan, Hongxia Zheng, Huajin Chen, Zhifang Lin
https://arxiv.org/abs/2510.04228

Designing Coherent Optical Environment for Dynamic Optical Manipulation with a Simple Control Beam
We propose a framework for designing coherent optical environments that enable versatile and dynamic optical manipulation. In contrast to conventional material-based near-field platforms, our approach employs a structured coherent light field -- optimized via a back-propagation-based inverse design algorithm -- as the manipulation environment. This light-based platform allows a simple control beam, such as a single plane wave or a low-numerical-aperture Gaussian beam, to steer micro-objects eff…

Optical Design Pathways to Fluidic Space-Assembled Reflectors & Dual-Configuration Spectrographs for Characterizing Exo-Earths
Enrico Biancalani, Edward Balaban, Ruslan Belikov, Eduardo Bendek, Valeri Frumkin, Israel Gabay, Guangjun Gao, Qian Gong, Christine Gregg, Tyler Groff, Joseph Howard, Omer Luria, Michael McElwain, Lee Mundy, Rachel Ticknor, Sylvain Veilleux, Neil Zimmerman

Optical Design Pathways to Fluidic Space-Assembled Reflectors & Dual-Configuration Spectrographs for Characterizing Exo-Earths
$\textbf{Fluidic Telescopes}$ | We present a conceptual framework for optically designing space-assembled telescopes whose primary mirror is formed $\textit{in situ}$ via the enabling, scale-invariant technology of fluidic shaping. In-space assembly of optical reflectors can solve light-gathering aperture scaling, which currently limits space-borne optical telescopes. Our compass reduces the top-level optical design trade to three types of avenues -- a fluidic pathway, a legacy one buildin…

Low-Complexity Receiver Design for Multicarrier CAPA-based Systems in Doubly-Dispersive Channels
Kuranage Roche Rayan Ranasinghe, Giuseppe Thadeu Freitas de Abreu, Emil Bj\"ornson
https://arxiv.org/abs/2509.24941

Low-Complexity Receiver Design for Multicarrier CAPA-based Systems in Doubly-Dispersive Channels
We propose a novel low-complexity receiver design for multicarrier continuous aperture array (CAPA) systems operating over doubly-dispersive (DD) channels. The receiver leverages a Gaussian Belief Propagation (GaBP)-based framework that hinges only on element-wise scalar operations for the detection of the transmitted symbols. Simulation results for the orthogonal frequency division multiplexing (OFDM), orthogonal time frequency space (OTFS), and affine frequency division multiplexing (AFDM) wa…

Ultracompact Wide-FOV Near-infrared Camera with Wafer-level Manufactured Meta-Aspheric Lens
Chuirong Chi, Qichao Hou, Guangyuan Zhao, Qiang Song, Shengyuan Xu, Yanling Piao, Mengjie Qin, Yanan Hu, Chaoping Chen, Weiwei Cai, Yuan Chen, Xin Yuan, Huigao Duan
https://arxiv.org/abs/2509.23599

Ultracompact Wide-FOV Near-infrared Camera with Wafer-level Manufactured Meta-Aspheric Lens
Overcoming the trade-off between wide field of view (FOV) and compactness remains a central challenge for integrating near-infrared (NIR) imaging into smartphones and AR glasses. Existing refractive NIR optics cannot simultaneously achieve ultra-wide angles above 100° and ultrathin total track length (TTL) below 5 mm, limiting their use in portable devices. Here, we present a wafer-level-manufactured meta-aspheric lens (MAL) that achieves a 101.5° FOV, 3.39 mm TTL, and F/1.64 aperture within …

Short-wave infrared broadband up-conversion imaging by using a noncritical phase matched bulk KTiOPO$_4$ crystal
Xiaohua Wang, Zhaoqizhi Han, Zhenghe Zhou, Jinpeng Li, Bowen Liu, He Zhang, Yinhai Li, Zhiyuan Zhou, Baosen Shi
https://arxiv.org/abs/2509.20955

Short-wave infrared broadband up-conversion imaging by using a noncritical phase matched bulk KTiOPO$_4$ crystal
Compared to cryogenically cooled conventional detectors, up-conversion detection enables efficient room-temperature short-wave infrared (SWIR) imaging. Although quasi-phase-matching (QPM) in periodically poled crystals offers advantages, the small crystal aperture (typically 1 mm$\times$3 mm) limits resolution. Non-poled crystals enable larger apertures but suffer walk-off aberrations. This work overcomes these limitations by using a noncritical phase matched (NCPM) KTiOPO$_4$ crystal (6 mm$\ti…

Subdiffraction confinement and non-diffractive propagation of optical Stokes skyrmions enabled by a super-oscillatory metalens
Jing He, Chengda Song, Wei Li, Fangwen Sun, Guanghui Yuan
https://arxiv.org/abs/2509.19917

Subdiffraction confinement and non-diffractive propagation of optical Stokes skyrmions enabled by a super-oscillatory metalens
Optical Stokes skyrmions have garnered extensive interest due to their intrinsic topological robustness and potential in informatics.However, most research remains confined to paraxial, low-numerical-aperture (low-NA) regimes, where their large transverse dimensions restrict broader applications.Under high-NA focusing, the polarization texture typically degrades or transforms abruptly as the beam traverses the focal region, hindering topology-preserving transport.In this work, we propose a stra…