Phase Profile Research Articles

Performance Analysis of a Wireless Power Transfer System Employing the Joint MHN-IRS Technology

The present study is concerned with the power transfer efficiency enhancement using a combination of the multi-hop node (MHN) and the Intelligent Reflecting Surface (IRS)-based passive beamforming technologies. The primary objective is to ensure a high RF-DC converter power conversion efficiency (PCE) used at the receiving end, which is difficult to achieve due to path loss and multi-path propagation. An electronically tunable reconfigurable reflectarray (RRA) designed to operate at the sub-GHz ISM band (865.5 MHz) is utilized to implement the IRS concept. Both the MHN and RRA were developed and studied in our earlier research. The RRA redirects the reflected power-carrying wave amplified by the MHN toward the intended receiver. It comprises two layers: the RF layer containing tunable phase shifters and the ground plane. Each phase shifter comprises two identical eight-shaped metal patches coupled by a pair of varactor diodes used to achieve the reflection phase tuning. The phase gradient method is used to synthesize the RRA phase profiles, ensuring different desired reflection angles. The RRA prototype, composed of 36 phase shifters, is employed in conjunction with the MHN equipped with two antennas and an amplifier. The RRA parameter optimization is accomplished by randomly varying the varactor diode voltages and measuring the corresponding received power levels until the power reflected in the desired direction is maximized. Two measurement scenarios are examined: power transmission without and with the MHN. In the first scenario, the received power is calculated and measured at several distinct beam steering angles for different distances between the Tx antenna and RRA. The same procedure is applied to different distances between the RRA and MHN in the second scenario. The effect of slight deviations in the operating frequency from the designed one (865.5 MHz) on the RRA performance is also examined. Additionally, the received power levels for both scenarios are estimated via full-wave analysis performed using the full-wave simulation software Ansys HFSS 2023 R1. A Huygens’ surface equivalence principle-based model decomposition method was developed and employed to reduce the CPU time. The calculated results are consistent with the measured ones. However, some discrepancies attributed to the adverse effect of RRA diode biasing lines, manufacturing tolerances, and imperfection of the indoor environment model are observed.

Single-layer multiplexed metasurfaces with on-demand polarization encoding based on a symmetric Jones matrix

Waveplates provide precise control over the state of polarization and are essential components in various technologies and scientific disciplines, greatly enhancing the performance of optical systems. Recently, advancements in metasurface technology have enabled the miniaturization of bulky optical components that manipulate polarization states while mitigating insertion loss. Nevertheless, generating vortex beams with specific topological charges within the desired polarization channels remains a significant challenge when utilizing versatile metasurface-based wave plates. This work presents a generalized design strategy for multifunctional metasurfaces, demonstrated through simulations and experiments, by varying the parametric conditions that facilitate the spin decoupling mechanism. Independent encoding of spin-polarized channels is achieved by integrating both geometric and propagation phase profiles into silicon pillar designs that exhibit birefringent effects. Meta-waveplates designed for operator computational mechanisms can effectively exhibit the behavior of orbital coupling from spin angular momentum (SAM) to orbital angular momentum (OAM) within a predetermined polarization channel. Also, OAM beams with topological charge evolution behavior in the longitudinal direction are further demonstrated, effectively enhancing the design freedom of multifunctional meta-waveplates. This research paves the way for developing multifunctional, high-performance, and ultra-compact terahertz meta-devices.

Short-course radiotherapy (SCRT) followed by fruquintinib plus adebrelimab and CAPOX in the total neoadjuvant therapy of locally advanced rectal cancer (LARC): A multicenter, single-arm, open-label, phase II study (UNION TNT).

192 Background: We have demonstrated that neoadjuvant SCRT followed by PD-1 inhibitor plus CAPOX for LARC patients (pts) showed a higher pCR rate and a well-tolerated safety profile in phase III UNION study. Fruquintinib is a potent and highly selective VEGFR inhibitor, which had been approved for previously treated mCRC pts. This study aimed to investigate the efficacy and safety of SCRT followed by fruquintinib plus adebrelimab and CAPOX as a total neoadjuvant therapy for high-risk LARC pts. Methods: In this prospective, open-label, multi-centers, single-arm phase 2 study (NCT06234007), pts diagnosed with newly diagnosed and high risk LARC were recruited. Pts received SCRT (25Gy/5f) followed by six cycles of fruquintinib (4mg, qd, po, q3w,for the initial 6 pts in the safety run-in period, dosage would be adjusted based on dose-limited toxicities in the 1st cycle) combined with adebrelimab (1200mg, iv, d1, q3w) and CAPOX (q3w). Primary endpoint was CR rate (including clinical CR & pathologic CR). Secondary endpoints included 3-year EFS rate, OS, R0 resection rate and safety. Results: As of 30 Aug 2024, 45 pts were enrolled (median age 59 years [range: 24-75], 26 males, 23 clinical T4 stage and 20 clinical N2 stage, 36 with EMVI positive, 31 with MRF positive, 22 tumor located ≤5cm from the anal verge). Up to 20 Sep 2024, all pts completed SCRT, 73.33% (33/45), 57.78% (26/45) and 31.11% (14/45) pts completed two, four and six cycles of combination therapy, respectively. At data cut-off, of 33 pts included in the efficacy analysis, 28 pts underwent MRI examination and mrTRG results were available, the remaining 5 pts had early surgery due to AEs/serious AEs. 35.7% (10/28) and 46.43% (13/28) pts were classified as mrTRG1 and mrTRG2, respectively. Of 19 pts who underwent surgery, R0 rate was achieved in all 19 pts (100%) and pCR was achieved in 12 pts (63.16%). Moreover, 1 pt achieved cCR during neoadjuvant therapy, thus the treatment strategy provided a CR rate of 65% (1 cCR plus 12 pCR divided by 20). Grade 3/4 adverse effects (AEs) occurred in 16 pts (47.06%), and most commonly were lymphocyte count decreased (n=6, 18.18%), diarrhea (n=5, 15.15%) and AST increased (n=2, 6.06%). 4 serious AEs reported with intestinal perforation and all achieved pCR after surgery therapy. No treatment related death was reported. Conclusions: SCRT followed by fruquintinib combined with adebrelimab and CAPOX as a total neoadjuvant therapy showed promising CR rate and favorable pCR for high-risk LARC pts, and the safety profile was generally manageable. This treatment strategy might be a potential option as neoadjuvant therapy for high-risk LARC pts. Updated data will be presented in the future. Clinical trial information: NCT06234007 .

Nonlocal Huygens’ meta-lens for high-quality-factor spin-multiplexing imaging

Combining bright-field and edge-enhanced imaging affords an effective avenue for extracting complex morphological information from objects, which is particularly beneficial for biological imaging. Multiplexing meta-lenses present promising candidates for achieving this functionality. However, current multiplexing meta-lenses lack spectral modulation, and crosstalk between different wavelengths hampers the imaging quality, especially for biological samples requiring precise wavelength specificity. Here, we experimentally demonstrate the nonlocal Huygens’ meta-lens for high-quality-factor spin-multiplexing imaging. Quasi-bound states in the continuum (q-BICs) are excited to provide a high quality factor of 90 and incident-angle dependence. The generalized Kerker condition, driven by Fano-like interactions between q-BIC and in-plane Mie resonances, breaks the radiation symmetry, resulting in a transmission peak with a geometric phase for polarization-converted light, while unconverted light exhibits a transmission dip without a geometric phase. Enhanced polarization conversion efficiency of 65% is achieved, accompanied by a minimal unconverted value, surpassing the theoretical limit of traditional thin nonlocal metasurfaces. Leveraging these effects, the output polarization-converted state exhibits an efficient wavelength-selective focusing phase profile. The unconverted counterpart serves as an effective spatial frequency filter based on incident-angular dispersion, passing high-frequency edge details. Bright-field imaging and edge detection are thus presented under two output spin states. This work provides a versatile framework for nonlocal metasurfaces, boosting biomedical imaging and sensing applications.

Physics-based generative adversarial network for real-time acoustic holography.

Acoustic holography (AH) encodes the acoustic fields in high dimensions into two-dimensional holograms without information loss. Phase-only holography (POH) modulates only the phase profiles of the encoded hologram, establishing its superiority over alternative modulation schedules due to its information volume and storage efficiency. Moreover, POH implemented by a phased array of transducers (PAT) facilitates active and dynamic manipulation by independently modulating the phase of each transducer. However, existing algorithms for POH calculation suffer from a deficiency in terms of high fidelity and good real-time performance. Thus, a deep learning algorithm reinforced by the physical model, i.e. Angular Spectrum Method (ASM), is proposed to learn the inverse physical mapping from the target field to the source POH. This method comprises a generative adversarial network (GAN) evaluated by soft label, which is referred to as soft-GAN. Furthermore, to avoid the intrinsic limitation of neural networks on high-frequency features, a Y-Net structure is developed with two decoder branches in frequency and spatial domain, respectively. The proposed method achieves the reconstruction performance with a state-of-the-art (SOTA) Peak Signal-to-Noise Ratio (PSNR) of 24.05dB. Experiment results demonstrated that the POH calculated by the proposed method enables accurate and real-time hologram reconstruction, showing enormous potential for applications.

Amplitude and Phase Imaging of CW-THz Waves Using a Photomixing System with Coherent Detection

Continuous-Wave Terahertz (CW-THz) phase and amplitude imaging provides valuable insights into the interaction between THz waves and matter, particularly in low-absorption materials. This information is also essential for enhancing CW-THz beam profiling, a critical aspect in the design of free-space THz devices. Hereby, we introduce a single-pixel THz amplitude and phase imaging technique based on frequency scanning and fringe analysis, incorporated into a straightforward experimental setup. We validate the usefulness of the proposed approach by demonstrating two representative case studies. The first is a 3-D measurement of the amplitude and phase profile of a THz wave that is transmitted through a 3-D printed metalens. The second is beam profiling of a THz beam emitted from a photomixer antenna. In both cases, our results are in excellent agreement with previous predictions and validate the usefulness of this imaging technique. As such, we believe that the demonstrated approach will provide an important tool in the quest for establishing THz as an important method for a myriad of applications, including imaging, range finding and metrology.

High‐Isolation Multidimensional Holography Multiplexing in Non‐Interleaved Metasurfaces

AbstractMetasurfaces have revolutionized holography by enabling high‐density channel multiplexing, positioning them as promising candidates for applications in full‐color holographic imaging, optical data storage, and encryption. However, conventional non‐interleaved metasurfaces face limitations in the number of controllable dimensions, restricting the channels available in each dimension. Here, a novel high‐dimensional multiplexing scheme is introduced that significantly enhances both the channel multiplexing capacity and isolation in non‐interleaved metasurfaces. By integrating the Rayleigh‐Sommerfeld diffraction (RSD) formula into the Gerchberg‐Saxton (GS) algorithm and incorporating gradient descent optimization, the approach achieves precise phase profile control across multiple dimensions—extending the controllable parameters to include wavelength, polarization state, and spatial distance. This method enables simultaneous multiplexing of three polarization channels, three wavelength channels, and two focal plane distances, producing a total of 18 distinct, well‐isolated holographic channels with minimal crosstalk. These results showcase the powerful channel multiplexing and isolation capabilities of this non‐interleaved metasurface design, underscoring its potential to advance optical color imaging, secure data storage, and high‐capacity information transmission, thereby contributing to the development of next‐generation intelligent optical devices.

Broadband reflective terahertz metalens employing Bessel beams for enhanced efficiency and depth of focus.

This paper presents a reflective terahertz (THz) Bessel metalens with broadband operation in the frequency range of 0.80-1 THz. The design employs a near-wavelength, polarization-insensitive resonator to achieve a wideband response. Optimized at 0.89 THz, the metalens integrates a hyperbolic phase configuration combined with a conical phase profile. By varying the cone angle, the metalens attains a focusing efficiency of up to 76% and an extended depth of focus of 21.7λ. Simulations demonstrate superior performance compared to conventional focusing metalenses. This design shows significant potential for applications in terahertz imaging, communications, and sensing technologies.

Mode-bases gain difference for different phase profiles in few-mode erbium-doped fiber amplifiers

Mode-bases gain difference for different phase profiles in few-mode erbium-doped fiber amplifiers

Shared-aperture full-duplex Janus meta-lens for asymmetric focusing of electromagnetic waves

Janus metasurfaces have provided a platform for multiplexing diverse electromagnetic (EM) wave functionalities, which are determined by the intrinsic propagation direction of the EM wave. However, most existing approaches only utilize half of the metasurface aperture for each EM functionality. Here, we propose a method that employs receiver–transmitter Janus meta-atom to accomplish high-efficiency transmission and asymmetric phase responses. By fully implementing the direction-duplex strategy through these meta-atoms, we can directly assign asymmetric phase profiles to the Janus meta-lens in order to achieve a direction-selective focusing configuration, thereby effectively improving aperture utilization. Experimental validation is conducted in the microwave region to demonstrate the feasibility of the proposed method, showcasing potential applications of shared-aperture Janus metasurfaces in asymmetric imaging and multichannel information processing.

Continuously focus tunable 2D/3D switchable cylindrical liquid crystal microlens arrays for autostereoscopic displays.

Cylindrical microlens arrays are important optical elements for autostereoscopic display. Conventional fixed focal length cylindrical microlens arrays do not allow switching between 2D mode and 3D mode when constructing a 3D viewing zone. In contrast, cylindrical liquid crystal microlens arrays with zoom characteristics allow switching between 2D and 3D states, as well as adjusting the width of the sub-viewing zone. Therefore, based on the quantitative analysis of the geometrical structure of the viewing zone in different states, this paper proposes a continuous zoom type cylindrical liquid crystal microlens array structure, which is a liquid crystal cell composed of an array of plano-concave glass substrates and planar glass substrates. Theory and experiments show that it is close to a favorable parabolic phase profile at different driving voltages, and at the same time, it can realize a zoom range of 1.6mm-36 mm at a smaller driving voltage. The wide zoom range and excellent zoom effect make this structure particularly suitable for autostereoscopic display, and this characteristic can achieve the effect of switching between 2D and 3D by adjusting the shape of the central viewing zone.

Temporal modeling and AT profiles in the early phase of Alzheimer's disease

Background Identifying markers that have predictive value for disease progression and clinical manifestations, such as mild cognitive impairment (MCI), is important to detect Alzheimer's disease (AD) early. Objective In this study, we combined biomarkers from amyloid and tau pathologies (AT profiles) with the prediction of diagnosis and the temporal evolution of clinical symptoms. Methods Multiple disease progression models were developed through supervised and unsupervised techniques via a two-stage data-driven approach. Models whose natural histories most closely resembled the diagnostic predictions were selected. Finally, various hypotheses regarding the progression of cognitive decline were tested using longitudinal patient data and AT profiles. Results At baseline, 22.5% of the cognitively unimpaired (CU) individuals and 46.2% of the CU converters (who progressed to MCI during the first four years) in the studied population had amyloid pathology (A+). Only a small subset of neuropsychological measures was used to predict cognitive decline and its timeline. The study revealed that amyloid pathology occurred approximately 5 years after cognitive decline in the population under investigation. Additionally, patients who were A+ at baseline experienced a more accelerated progression toward cognitive decline than those who were not (A−). Conclusions Based on the proposed natural histories and cross-sectional and longitudinal analysis of AD markers, the results indicate that only a single cerebrospinal fluid sample is necessary during the early phase of AD. The progression from CU to MCI and its timeline can be predicted exclusively through neuropsychological measures.

Label-free imaging flow cytometry for cell classification based directly on multiple off-axis holographic projections.

Imaging flow cytometry allows highly informative multi-point cell analysis for biological assays and medical diagnosis. Rapid processing of the imaged cells during flow allows real-time classification and sorting of the cells. Off-axis holography enables imaging flow cytometry without chemical cell staining but requires digital processing to the optical path delay profile for each frame before the cells can be classified, which slows down the overall processing throughput. We present a method for real-time cell classification via label-free quantitative imaging flow cytometry using digital holography, offering a comprehensive representation of cellular structures, without the need for digital processing before automatic cell classification. We aim to develop an automatic cell classification scheme based directly on the off-axis holographic projections of the cells during flow and test it for stain-free imaging flow cytometry of white blood cells. After building a dedicated off-axis holographic microscopy system for acquiring white blood cells during flow, we apply deep-learning classification directly in the off-axis hologram space, rather than in the quantitative phase profile space. This way, we simplify computational processes and allow a significant increase in the cell classification throughput. In addition, by utilizing multiple-viewpoint holographic projections of the cells rotated during flow, instead of using a single projection, we obtain better classification results due to the additional cellular information gained. Our technique demonstrates increasing accuracy with additional viewpoint holographic projections from the optical system, achieving a 7.69% improvement when processing ten interferometric projections compared with a single interferometric projection (regular off-axis hologram). Our technique also outperforms using multiple optical path delay profile projections, requiring off-axis holographic digital preprocessing, by 17.95%, because the holographic projections are analyzed directly without preprocessing and includes the amplitude information as well. Our cell classification approach has great potential for high-throughput, high-content, label-free imaging flow cytometry for classification of large-scale cellular datasets and real-time cell classification during flow in clinical settings.

Dynamics and manipulation of ultrashort laser pulses via plasma shutter

The characterization and manipulation of ultrashort high-intensity laser pulses were investigated both numerically and experimentally using an ultrathin foil as plasma shutter. Our work revealed a laser intensity enhancement with a clean and steepened leading edge when the pulse passed through an expanded moderate-density plasma. The fast dynamics of laser–plasma interaction in underdense, transparent, and overdense regimes were elucidated by measuring the temporal-spatial intensity and phase profiles of the transmitted pulses. Key nonlinear effects such as relativistic self-focusing, self-phase modulation, self-induced transparency, and hole-boring were identified as factors influencing laser pulse shaping, with their impact determined by the plasma density. Our approach allows for the robust utilization of the plasma shutter in existing laser facilities without additional requirements. By controlling the spatiotemporal properties of high-power laser pulses, it opens up the possibility for developing compact laser-driven particle accelerators, ultrabright radiation sources, and plasma photonics.

Frequency-stable liquid crystal lenses using a circumferentially segmented concentric electrode.

A circumferentially segmented concentric electrode is proposed for a large-aperture liquid crystal (LC) lens to address the issue of phase deviation from the parabolic profile caused by alternating current (AC) driving voltages. This design offers a simple and effective method for realizing large-aperture LC lenses that maintain a stable parabolic phase profile across a wider frequency range. An equivalent circuit model of the LC lens is established, and analysis shows that increasing the number of electrode segments brings the voltage distribution closer to a parabolic profile. In the experiments, LC lenses with a 5 mm aperture and a 30 µm LC layer were prepared using both unsegmented and eight-segmented electrodes. The results demonstrate that the segmented electrode design notably enhances frequency stability, with the lens maintaining a nearly ideal parabolic phase profile over a frequency range of up to 8 kHz.

Serum Levels of Lead and Selected Acute Phase Proteins in Patients with Substance Use Disorders

Background: Chronic inflammation, immune system dysfunction and elevation in the levels of toxic metals such as lead (Pb) are common observations in patients with substance use disorders (SUD). However, there is little information on the acute phase profile of SUD patients with different serum levels of Pb. Therefore, serum levels of selected acute phase proteins in SUD patients with different serum levels of Pb were determined in this study. Methods: A total of 84 adults consisting of 45 patients with SUDs and 39 controls were enrolled into this case-control study. Serum levels of Pb, albumin and C-reactive protein (CRP) were determined using Atomic Absorption Spectrophotometer, bromocresol green (BCG) colorimetric method, and ELISA, respectively. Thereafter, CRP-albumin ratio (CAR) was calculated as appropriate. Results: Serum levels of Pb and albumin were significantly higher in patients with SUDs compared with the controls. Considering variation in acute phase proteins based on Pb level, the serum level of albumin was significantly lower, while the serum CRP level and CAR were slightly higher in patients with SUDs whose Pb level was higher than 5 µg/dL compared with patients whose Pb level was ≤5 µg/dL. No significant differences were observed in the levels of Pb, albumin, CRP, CAR in patients with SUDs who abuse single substance compared with those who abuse multiple substances. Conclusion: SUD is associated with increased serum levels of Pb and albumin, and alteration in the serum levels of acute phase proteins appears to be influenced by the serum Pb level. Therefore, there is the need for routine measurement of Pb level in patients with SUDs as they could benefit from therapeutic interventions involving chelation of Pb which could prevent disordered acute phase responses in the patients and facilitate optimal response to antipsychotics.

High-efficiency, dynamic optical beam steering device using Pancharatnam phase

A large aperture, non-mechanical beam steering device is proposed that demonstrates a defect free, continuous phase profile, for a high-efficiency beam steering. The device uses a fringe field electrode structure, a vertical surface alignment of the liquid crystal director, and, to our knowledge, a novel two-step voltage application method to produce a linear Pancharatnam phase gradient that can be electrically tuned. An example optical beam steering device is numerically calculated and demonstrates steering angles of IR light (1550 nm) from less than 1 deg to greater than 10 deg with an efficiency of over 80%. This new approach provides previously unobtainable beam steering performance in a single layer, Pancharatnam phase device.

Spin-Orbit-Locking Vectorial Metasurface Holography.

Vectorial metasurface holography, allowing for independent control over the amplitude, phase, and polarization distribution of holographic images enabled by metasurfaces, plays a crucial role in the realm of optical display, optical, and quantum communications. However, previous research on vectorial metasurface holography has typically been restricted to single degree of freedom input and single channel output, thereby demonstrating a very limited modulation capacity. This work presents a novel method to achieve multi-channel vectorial metasurface holography by harnessing spin-orbit-locking vortex beams. In each channel, the optical vectorial field is encoded with a pair of total angular momentums (TAMs) featuring two orthogonal spin angular momentums (SAMs) independently locked with arbitrary orbital angular momentums (OAMs). The methodology relies on a modified Gerchberg-Saxton algorithm, enabling the encoding of various TAM channels within a single phase profile. Consequently, a pure geometry-phase metasurface with a non-interleaved approach can be used to support such multi-channel vectorial holography, achieving high selectivity of both SAM and OAM, and offering precise routing and manipulation of complex light channels. The work presents a paradigm shift in the field of holography, offering promising avenues for high-density optical information processing and future photonic device design.

A spectrophotometric analysis and dust properties of classical nova V5584 Sgr

ABSTRACT In this work, optical observations of the nova V5584 Sgr are presented. These observations cover different phases including pre-maximum, early decline, and nebular. The spectra are dominated by hydrogen Balmer, Fe ii, and O i lines with P-Cygni profiles in the early phase, which are subsequently observed in complete emission. The presence of numerous Fe ii lines and low ejecta velocity aligns with the Fe ii type nova classification. From optical and NIR colours, it is clear that this nova manifests dust formation in the ejecta. The dust temperature and mass were estimated from a spectral energy distribution (SED) fit to the JHK band magnitudes and the Wide field Infrared Survey Explorer data. Light-curve analysis shows t$_2$ and t$_3$ values of $\sim$ 26 and $\sim$ 48 d, classifying the nova as moderately fast. The physical and chemical properties during early decline and later phases were evaluated using the photoionization code CLOUDY. The best-fitting model parameters from two epochs of multiwavelength spectra are compatible with a hot white dwarf source with a roughly constant luminosity of $\sim$(2.08 $\pm$ 0.10) $\times$ 10$^{36}$ erg s$^{-1}$. We find an ejected mass of $\sim$(1.59 $\pm$ 0.04) $\times$ 10$^{-4}$ M$_{\odot }$. Abundance analysis indicates that the ejecta is significantly enriched relative to solar values, with O/H = 30.2, C/H = 10.8, He/H = 1.8, Mg/H = 1.68, Na/H = 1.55, and N/H = 45.5 in the early decline phase, and O/H = 4.5, Ne/H = 1.5, and N/H = 24.5 in the nebular phase.

Harmonic achromatic metalens with a wide field of view for AR/VR applications

Abstract Metalens is a cutting-edge optical marvel, revolutionizes a plethora of applications like cameras, telescope, augmented reality (AR) and virtual reality (VR). Despite having ultrathin structure, lightweight nature, and multifunctionality, achievement of both achromatic imaging and wide field of view (WFOV) remains a persistent challenge. To address these concerns, here we present a novel approach using a harmonic metalens featuring a quadratic phase profile to achieve achromatic behavior and WFOV simultaneously. This innovation enables WFOV imaging using the Fourier transform of quadratic phase profile and achromatic behavior at RGB wavelengths (blue λ = 488 nm, green λ = 532 nm and red λ = 633 nm) with a WFOV of up to ± 45 ∘ . The designed harmonic metalens is polarization-insensitive, with a numerical aperture of 0.79, and it achieves a maximum focusing efficiency of ∼50% at a wavelength of 633 nm under normal incidence. Being polarization insensitive and achromatic, proposed scheme will certainly broaden the utilization of metalenses in AR/VR, displays and applications in imaging. © 2024 Optical Society of America.