Polarization Mode Research Articles

Study of surface plasmon resonance with zirconium oxide multilayer coatings of silver and gold films: reflection polarization modes and sensitivity

We propose a surface plasmon resonance (SPR) sensor based on multilayer films with silver (Ag) and gold (Au) interfaces coated with a thin layer of zirconium oxide (ZrO2) in Kretschmann configuration. A dielectric layer of ZrO2 acts as the prism coating and the second layer is deposited after the metal film in the dielectric/metal/dielectric (DMD) system. In order to achieve the best design for the sensor, the dependence of the sensitivity on the angle of incidence and the thickness of the alternating layer is comprehensively explored. The polarization change results are shown with the angles Ψ and ∆ which are the traditional ellipsometry measurement angles of the optical properties of the DMD system. The advantage of Ag/ZrO2 multilayers over Au and Au/ZrO2 for SPR refractive index detection in terms of sensitivity, as well as the Ag/ZrO2 interface offers the possibility of studies with promising features for SPR users to generalize this type of interface. The proposed DMD sensor is expected to find application in biochemical sensing due to its resolution.

Desorption electrospray ionization mass spectrometry imaging of latent fingerprints revealed by Oil Red O.

To optimize the ionization step independently from surface extraction, the ORO reagent and its mixture with model compounds (triolein and linoleic acid) were first studied in solution using high-resolution electrospray ionization tandem mass spectrometry (ESI-MS/MS). Then, DESI-MSI experiments were performed in both polarity modes for ORO-processed fingermarks deposited on pieces of paper used as porous substrates. ESI-MS of ORO reveals a complex mixture of azo dyes. Two main impurities detected beside the targeted species were characterized using MS/MS and then were usefully employed to produce DESI-MS images of fingermarks, decreasing the scanning rate to get sufficient ion abundance from natural fingerprints. ORO did not prevent chemical profiling, and one major added value of this pink dye was to produce MS images with contrast that cannot be obtained optically for some colored substrates. DESI-MS has demonstrated imaging compatibility with the application of ORO used to enhance latent fingerprints on paper and could also enable chemical profiling in natural fingermarks. In addition, MS images of ORO impurities were of higher quality than optical ones for fingerprints revealed on colored paper.

Highly sensitive refractive index sensing with a dual-band optically transparent ITO-based perfect metamaterial absorber for biomedical applications

In this paper, a dual-band optically transparent square-shaped perfect metamaterial absorber operating in the frequency range from 2 to 4 terahertz (THz) is proposed. The structure consists of an indium tin oxide (ITO)-based split ring resonator (SRR) structure with additional splits and rectangular inner strips to form the top layer over the lead glass substrate. Perfect absorption is attained in the frequencies of 2.089 and 3.892 THz with absorbances of 99.99% and 99.98% in TE polarization mode, respectively. Perfect absorption is also achieved in TM polarization mode at 2.23 THz. Broadband absorption is found in TM polarization mode with full width half maximum (FWHM) of 1.1742. The proposed structure has one polarization-insensitive band in TE polarization mode. Absorbance is greater than 80% and 90% in the successive absorption peaks even at 60° and 75° of incidence, respectively. The resonance frequency is sensitive to the refractive index of the medium. As a result, the proposed metamaterial structure may be implemented as a refractive index (RI) sensor with a high sensitivity of 1109 GHz/RIU and 1954 GHz/RIU in both absorption bands for a refractive index range of 1.34 to 1.40. It's interesting to note that the refractive index of most biological samples ranges from 1.3 to 1.39. The figure of merit (FOM) of the proposed sensor can reach as high as 10 and 14 for the 1st and 2nd frequency bands. As a result, the proposed sensor has a high sensitivity and can be employed in medical applications. Potential applications of the proposed absorber include imaging, biomedical sensing, etc.

Coherence-tailorable vector fiber source

Apart from the polarization and spatial mode, the degree of coherence (DoC), as a new degree of freedom (DoF), has actuated the control of structured optical fields beyond into a higher dimension. However, the control of DoC mainly focuses on the spatial coherence, and so far, there are no reports on the modulation of temporal coherence of the structured light. Here, a temporal coherence-tailorable vector fiber source is proposed and experimentally demonstrated. With a two-mode long-period fiber grating and polarization control, switchable transverse-mode outputs including azimuthally polarized mode TE01 and radially polarized mode TM01 are performed in an all-fiber compact regime. Benefitting from a tunable superfluorescent fiber source as the illumination of spatial mode control, the temporal coherence and the operating wavelength of vector beams can be simultaneously modulated. This work may not only advance a considerable protocol for creating and manipulating high-dimensional vectorial optical field, but also open up a promising avenue for potential applications in optical communication, high-resolution imaging, and particle trapping.

Nonlinear fiber effects in ultra-high power 10 × 10 Gbit/s WDM-IM free-space systems for satellite links.

We investigate an unexplored type of nonlinear impairments that will take place in a very short fiber after the booster amplifier in a Free Space Optical (FSO) system for space communications. In Earth-satellite links, optical power levels up to 100 W could be required at the transmitter side to achieve the foreseen 100 Gbit/s capacity, because of the extremely high losses. These systems thus need an optical booster amplifier having very high optical power and it should be connected to the transmitting telescope by means of a short fiber (few meters). Here, we discuss and investigate the impact of the nonlinear fiber effects by means of numerical simulations, and estimate the impairments in a Wavelength Division Multiplexing (WDM) 10 × 10 Gbit/s system with intensity modulation. The obtained results clearly indicate that, in this system, the most relevant effect is Four Wave Mixing. We proved that this can be observed as soon as the total power exceeds 20 W. Due to the short fiber length, the system impairments are not affected by chromatic dispersion or channel spacing. We demonstrate that an effective means to reduce the impact is by adopting Polarization Interleaving, i.e., odd and even channels with orthogonal state of polarization. This solution could not work in long terrestrial links because of polarization mode dispersion, yet it can be effectively exploited in short fiber patch cords. These results can be used as a guideline to control this type of impairment in high-power FSO systems for satellite links.

Optimizing auxiliary laser heating for Kerr soliton microcomb generation.

Auxiliary laser heating has become a widely adopted method for Kerr soliton frequency comb generation in optical microcavities, thanks to its reliable and easy-to-achieve merits for solving the thermal instability during the formation of dissipative Kerr solitons. Here, we conduct optimization of auxiliary laser heating by leveraging the distinct loss and absorption characteristics of different longitudinal and polarization cavity modes. We show that even if the auxiliary and pump lasers enter orthogonal polarization modes, their mutual photothermal balance can be efficient enough to maintain a cavity thermal equilibrium as the pump laser enters the red-detuning soliton regime, and by choosing the most suitable resonance for the auxiliary and pump lasers, the auxiliary laser power can be reduced to 20% of the pump laser and still be capable of warranting soliton generation. Moreover, we demonstrate soliton comb generation using integrated laser modules with a few milliwatt on-chip pump and auxiliary powers, showcasing the potential for further chip integration of the auxiliary laser heating method.

DaliWS: A High-Resolution Dataset with Precise Annotations for Water Segmentation in Synthetic Aperture Radar Images

The frequent occurrence of global flood disasters leads to millions of people falling into poverty each year, which poses immense pressure on governments and hinders social development. Therefore, providing more data support for flood disaster detection is of paramount importance. To facilitate the development of water body detection algorithms, we create the DaliWS dataset for water segmentation, which contains abundant pixel-level annotations, and consists of high spatial resolution SAR images collected from the GaoFen-3 (GF-3) satellite. For comprehensive analysis, extensive experiments are conducted on the DaliWS dataset to explore the performance of the state-of-the-art segmentation models, including FCN, SegNeXt, U-Net, and DeeplabV3+, and investigate the impact of different polarization modes on water segmentation. Additionally, to probe the generalization of our dataset, we further evaluate the models trained with the DaliWS dataset, on publicly available water segmentation datasets. Through detailed analysis of the experimental results, we establish a valuable benchmark and provide usage guidelines for future researchers working with the DaliWS dataset. The experimental results demonstrate the F1 scores of FCN, SegNeXt, U-Net, and DeeplabV3+ on the dual-polarization data of DaliWS dataset reach to 90.361%, 90.192%, 92.110%, and 91.199%, respectively, and these four models trained using the DaliWS dataset exhibit excellent generalization performance on the public dataset, which further confirms the research value of our dataset.

Multi‐Domain Detection Computational Imaging via Reconfigurable Metasurfaces MIMO System

AbstractA reconfigurable transmission metasurfaces (RTMs) excited by a multiple‐input multiple‐output (MIMO)( RTMs‐MIMO) antenna is designed to implement multi‐domain metamaterial computational imaging (MCI). Based on the receiver‐transmitter metasurfaces structure, four PIN diodes are applied to control the operating state of the RTMs. It enables arbitrary switching among four polarization transmission waves. A reverse‐induced current can be generated by adjusting the PIN diodes in the symmetrical position, resulting in a perfect 1‐bit phase modulation with a 3dB‐loss bandwidth of 15.38~19.89 GHz. A microstrip antenna with mushroom‐shaped parasitic patches is employed to implement the MIMO feeds. The ‐10dB bandwidth of MIMO antenna is compatible with the RTMs, and the maximum envelope correlation coefficient of 0.16 demonstrates good isolation between the MIMO feeds. In the MCI system constructed by the RTMs‐MIMO antennas, a transmission matrix H can be achieved by MIMO space beams, metasurfaces phase, metasurfaces polarization, and frequency modes. The correlation coefficient µg = 0.018 is achieved by the multi‐domain integration, allowing H to be highly non‐correlated. Based on the detection results of H, an imaging result with a relative reconstruction error of 0.372 is achieved. The designed MCI system therefore has unparalleled application prospects in the broad field of medical and military detection.

The Thousand-Pulsar-Array programme on MeerKAT – XII. Discovery of long-term pulse profile evolution in seven young pulsars

ABSTRACT A number of pulsars are known to have profile evolution on time-scales of months, often correlated with spin-down rate changes. Here, we present the first result from 3 yr of monitoring observations from MeerKAT as part of the Thousand Pulsar Array programme. This programme obtains high-fidelity pulse profiles for ∼ 500 pulsars, which enabled the detection of subtle changes in seven sources not previously known to exhibit long-term profile evolution. A 2D Gaussian convolution is used to highlight correlated emission variability in both the pulse phase and observing epoch direction. Simulations show that for one additional source the observed profile variability is likely to originate from stochastic single-pulse shape variability (jitter). We find that it is common for long-term profile variability to be associated with changes in polarization fractions, but not with polarization position angle (PA) changes. PA changes are expected if emission height changes or precession is responsible for the profile variability. PSR J1741−3927 is the only pulsar in our sample that shows correlated PA variability, and this is associated with orthogonal polarization mode activity. For the six other pulsars limits on possible emission height changes and impact angle changes are derived. These limits are consistent with the small changes in the total intensity profile shape. None of the sources show detectable spin-down variability correlated with the emission changes, which are thought to be driven by magnetospheric current fluctuations. Therefore, the absence of correlated spin-down rate variability allows upper limits to be placed on changes in the magnetospheric charge density.

Dual-color emissive OLED with orthogonal polarization modes

Linearly polarized organic light-emitting diodes have become appealing functional expansions of polarization optics and optoelectronic applications. However, the current linearly polarized diodes exhibit low polarization performance, cost-prohibitive process, and monochromatic modulation limit. Herein, we develop a switchable dual-color orthogonal linear polarization mode in organic light-emitting diode, based on a dielectric/metal nanograting-waveguide hybrid-microcavity using cost-efficient laser interference lithography and vacuum thermal evaporation. This acquired diode presents a transverse-electric/transverse-magnetic polarization extinction ratio of 15.8 dB with a divergence angle of ±30°, an external quantum efficiency of 2.25%, and orthogonal polarized colors from green to sky-blue. This rasterization of dielectric/metal-cathode further satisfies momentum matching between waveguide and air mode, diffracting both the targeted sky-blue transverse-electric mode and the off-confined green transverse-magnetic mode. Therefore, a polarization-encrypted colorful optical image is proposed, representing a significant step toward the low-cost high-performance linearly polarized light-emitting diodes and electrically-inspired polarization encryption for color images.

Enantioselective control in chiral crystallization of ethylenediamine sulfate using optical trapping with circularly polarized laser beams.

In this study, we conducted successful experiments on ethylenediamine sulfate (EDS), an organic compound, to investigate its enantioselectivity in chiral crystallization. We employed optical trapping with circularly polarized laser beams, using a continuous wave laser at 1064nm. By focusing the laser at the air-solution interface of a heavy water-saturated EDS solution, the formation of sub-micrometer-sized chiral EDS crystals was verified. Two generated enantiomorphs (d-crystal and l-crystal) were identified by the rotating analyzer method. The enantioselectivity in the chiral crystallization of EDS was assessed through 30 to 60 times experiments conducted under various conditions of laser powers and polarization modes, utilizing the count of generated crystals for each enantiomorph in the evaluation. Circularly polarized lasers at a specific power created an imbalance in the generation probability of the enantiomorphs, resulting in crystal enantiomeric excess values of 23% and -30%. The enantioselectivity mechanism was explored from two perspectives: refractive index differences of two enantiomorphs and 3D helical optical forces. Study of the thermodynamic mechanism was insufficient to explain the outcomes. Conversely, the 3D helical optical force mechanism revealed that the forces acting on EDS clusters in solution induced helical fluid motion, driving EDS nucleation, with the helicity of fluid motion determining the crystal's chirality. This approach will present new insights into chirality in industrial and research fields, with potential applications in regard to improving optical resolution and addressing the origin of homochirality.

A Millimeter-Wave Broadband Multi-Mode Substrate-Integrated Gap Waveguide Traveling-Wave Antenna with Orbit Angular Momentum.

Orbit angular momentum (OAM) has been considered a new dimension for improving channel capacity in recent years. In this paper, a millimeter-wave broadband multi-mode waveguide traveling-wave antenna with OAM is proposed by innovatively utilizing the transmitted electromagnetic waves (EMWs) characteristic of substrate-integrated gap waveguides (SIGWs) to introduce phase delay, resulting in coupling to the radiate units with a phase jump. Nine "L"-shaped slot radiate elements are cut in a circular order at a certain angle on the SIGW to generate spin angular momentum (SAM) and OAM. To generate more OAM modes and match the antenna, four "Π"-shaped slot radiate units with a 90° relationship to each other are designed in this circular array. The simulation results show that the antenna operates at 28 GHz, with a -10 dB fractional bandwidth (FBW) = 35.7%, ranging from 25.50 to 35.85 GHz and a VSWR ≤ 1.5 dB from 28.60 to 32.0 GHz and 28.60 to 32.0 GHz. The antenna radiates a linear polarization (LP) mode with a gain of 9.3 dBi at 34.0~37.2 GHz, a l = 2 SAM-OAM (i.e., circular polarization OAM (CP-OAM)) mode with 8.04 dBi at 25.90~28.08 GHz, a l = 1 and l = 2 hybrid OAM mode with 5.7 dBi at 28.08~29.67 GHz, a SAM (i.e., left/right hand circular polarization (L/RHCP) mode with 4.6 dBi at 29.67~30.41 GHz, and a LP mode at 30.41~35.85 GHz. In addition, the waveguide transmits energy with a bandwidth ranging from 26.10 to 38.46 GHz. Within the in-band, only a quasi-TEM mode is transmitted with an energy transmission loss |S21| ≤ 2 dB.

Wave-Guided Surface Plasmonic Resonance Induced Giant and Tunable Photonic Spin Hall Effect with Polarization Mode Control

Wave-Guided Surface Plasmonic Resonance Induced Giant and Tunable Photonic Spin Hall Effect with Polarization Mode Control

Polarization modes of gravitational waves in general modified gravity: General metric theory and general scalar-tensor theory

Polarization modes of gravitational waves in general modified gravity: General metric theory and general scalar-tensor theory

Identification and Validation of Genes Related to Macrophage Polarization and Cell Death Modes Under Mycobacterium tuberculosis Infection.

To investigate the correlation between M1/M2 macrophages (M1/M2 Mφ) and cell death mode under Mycobacterium tuberculosis (Mtb) infection. Raw gene expression profiles were collected from the Gene Expression Omnibus (GEO) database. Genes related to different cell death modes were collected from the KEGG, FerrDb and GSEA databases. The differentially expressed genes (DEGs) of the gene expression profiles were identified using the limma package in R. The intersection genes of M1/M2 Mφ with different cell death modes were obtained by the VennDiagram package. Hub genes were obtained by constructing the protein-protein interactions (PPI) network and Receiver Operating Characteristic (ROC) curve analysis. The expression of cell death modes marker genes and Hub genes were verified by Western Blot and Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). Bioinformatics analysis was performed to screen Hub genes of Mtb-infected M1 Mφ and different cell death modes, naming NFKB1, TNF, CFLAR, TBK1, IL6, RELA, SOCS1, AIM2; Hub genes of Mtb-infected M2 Mφ and different cell death modes, naming TNF, BIRC3, MAP1LC3C, DEPTOR, UVRAG, SOCS1. Combined with experimental validation, M1 Mφ under Mtb infection showed higher expression of death (including apoptosis, autophagy, ferroptosis, and pyroptosis) genes compared to M2 Mφ and genes such as NFKB1, TNF, CFLAR, TBK1, IL6, RELA, AIM2, BIRC3, DEPTOR show differential expression. NFKB1, TNF, CFLAR, TBK1, IL6, RELA, AIM2 in Mtb-infected M1 Mφ, and TNF, BIRC3, DEPTOR in Mtb-infected M2 Mφ might be used as potential diagnostic targets for TB. At early stage of Mtb infection, apoptosis, autophagy, ferroptosis, and pyroptosis occurred more significantly in M1 Mφ than that in M2 Mφ, which may contribute to the transition of Mtb-infected Mφ from M1-dominant to M2-dominant and contribute to the immune escape mechanisms of Mtb.

High efficiency holographic impedance metasurface for dual circular polarized OAM waves

AbstractThis paper proposes a high aperture efficiency (AE) small size tensor holographic impedance metasurface (THIMS), which has the ability to create circular polarized (CP) high purity orbital angular momentum (OAM) multi‐beams with flexibly independent control of the individual beam direction, polarization and OAM mode. The tensor unit cell is a cross‐slotted circular patch. We design a THIMS at 14.6 GHz for dual CP OAM beams: Beam‐I (LHCP, l = 1, θ1 = 30°, φ1 = 0°), Beam‐II (RHCP, l = −1, θ2 = 30°, φ2 = 180°). The developed tensor dual CP THIMS has the following advantages: high purity in xoy plane at z = 9.73 λ (λ wavelength, measured purity 88.4% for Beam‐I, and 93.5% for Beam‐II), high AE 25.1%, and small size 5.986 λ × 5.986 λ × 0.0618 λ. The calculated, simulated and measured results agree well. The generated dual CP OAM beams have potential applications for high‐capacity wireless communication, radar high resolution imaging, and rotation velocity measurement.

Design of polycarbonate‐based dual‐band conformal frequency‐selective surface for 4G/5G shielding applications

AbstractIn this work, a compact conformal swastik frequency‐selective surface (FSS) has been proposed for shielding 4G/5G signals. The resonating unit of FSS is realized using swastik geometry. The proposed FSS offers resonance at 1800 MHz for 4G band and 3300 MHz for sub‐6 5G band. The unit‐cell dimension is 0.11λ0 × 0.11λ0, where λ0 is the free space wavelength corresponding to the lowest resonating frequency. The proposed FSS provides a stable response for both the TE and TM modes of polarization up to 60°. To validate the simulated results, the FSS was fabricated and tested. The simulation and measurement results are in good agreement.

Photonic MMW Generation Using PM-DPMZM for Full Duplex 32×10 Gbps RoF-WDM System

Abstract This paper presents a study of a 32×10 Gbps Radio over Fiber and Wavelength Division Multiplexing (RoF-WDM) full-duplex system that uses Phase Modulators and a Dual-Port Mach-Zehnder Modulator (PMs-DPMZM) for bidirectional data transfer. The system employs Millimeter-Wave (MMW) signaling over optical fiber and focuses on selecting a technology that provides high transmission capacity per wavelength, improved spectral efficiency, and resistance against optical transmission impairments. The proposed method was validated using simulation results to confirm the efficiency of the proposed system in generating a 40 GHz signal and efficiently detecting and modulating the RF signals. The results demonstrate that the system exhibits strong resistance against dispersion, non-linear effects, and noise, delivering satisfactory performance for distances of up to 220 km. By analyzing the input power, the paper establishes a relationship between input power and signal quality, revealing that an optimal power of 0 dBm leads to an improved Quality Factor (QF) and reduced transmission errors. Furthermore, the evaluation of received optical power indicates the power level required to maintain an acceptable error rate, approximately -20.9690 dBm for downstream data transfer and -20.7245 dBm for upstream data transfer at the BER limit. The simulation performance also demonstrates the transmission efficiency achieved through a high Polarization Mode Dispersion (PMD) coefficient of up to 0.8. The analytical calculations conducted in this work provide valuable insights for optimizing and enhancing the performance of RoF-WDM networks.

Polarization dependent gain in Raman fiber amplifiers with multiple pumps.

In this paper, the polarization dependent gain (PDG) in Raman fiber amplifiers (RFAs) with multiple pumps is studied thoroughly. A comprehensive model, which takes the random polarization mode dispersion, the nonlinear coupling between the pumps, and the degree of polarization (DOP) of the pumps into account, is proposed. The complex nonlinear and random coupling inside the optical fiber is described by a set of nonlinear stochastic differential equations (SDEs), which enable co-simulation of the polarized part and the depolarized part of the multiple pumps. It is revealed that the average PDG and the PDG standard deviation are linearly proportional to the DOP of the pumps, which agrees with the single mode case. More importantly, when the pump wavelength is far away from the signal amplification range (pump-signal wavelength difference larger than 100 nm), its DOP still affects the PDG of the signal. Such a phenomenon is caused by the fact that the pumps interact with each other and the pump DOP could transfer among the pumps, which could enhance the PDG of the RFA. The findings in the work will have important implications for the design of the optical transmission systems with the multi-pump RFAs.

Actively Tunable "Single Peak/Broadband" Absorbent, Highly Sensitive Terahertz Smart Device Based on VO2.

In recent years, the development of terahertz (THz) technology has attracted significant attention. Various tunable devices for THz waves (0.1 THz-10 THz) have been proposed, including devices that modulate the amplitude, polarization, phase, and absorption. Traditional metal materials are often faced with the problem of non-adjustment, so the designed terahertz devices play a single role and do not have multiple uses, which greatly limits their development. As an excellent phase change material, VO2's properties can be transformed by external temperature stimulation, which provides new inspiration for the development of terahertz devices. To address these issues, this study innovatively combines metamaterials with phase change materials, leveraging their design flexibility and temperature-induced phase transition characteristics. We have designed a THz intelligent absorber that not only enables flexible switching between multiple functionalities but also achieves precise performance tuning through temperature stimulation. Furthermore, we have taken into consideration factors such as the polarization mode, environmental temperature, structural parameters, and incident angle, ensuring the device's process tolerance and environmental adaptability. Additionally, by exploiting the principle of localized surface plasmon resonance (LSPR) accompanied by local field enhancement, we have monitored and analyzed the resonant process through electric field characterization. In summary, the innovative approach and superior performance of this structure provide broader insights and methods for THz device design, contributing to its theoretical research value. Moreover, the proposed absorber holds potential for practical applications in electromagnetic invisibility, shielding, modulation, and detection scenarios.