Anisotropic medium sensing controlled by bound states in the continuum in polarization-independent metasurfaces.

Bound states in the continuum (BICs) with infinite quality factor (Q-factor) and significant field enhancement pave the way for realizing highly sensitive optical sensors with enhanced light-matter interactions on the nanoscale. However, current optical sensing methods are difficult to discriminate between isotropic and anisotropic media from resonance spectral lines, resulting in optical sensing methods still being limited to isotropic media. In this work, we demonstrate that BICs can be realized by modulating the period of structural units to convert BICs to QBICs without changing their space group symmetry, and propose a polarization-independent metasurfaces-based realization of highly sensitive refractive index sensors for isotropic and anisotropic media as well as discrimination. We propose a metasurface of tetrameric silicon nanoboxes with C4 symmetry as structural units to achieve the conversion of BICs to QBICs by modulating the period of structural units without changing the geometry of the structure. Two QBICs modes dominated by electric toroidal dipole and magnetic toroidal dipole are identified by multipolar decomposition and electromagnetic distribution calculations. Meanwhile, we realize the refractive index detection and resolution of isotropic and anisotropic media based on polarization-independent metasurfaces combined with isotropic and anisotropic media layers. Our work provides what we believe to be a new method for realizing the fast resolution and refractive index optical sensing of isotropic and anisotropic media, and offers new ideas for the design and application of polarization-independent metasurfaces.

Temporal soliton dynamics of synchronised ultrafast fibre lasers.

Synchronised ultrafast soliton lasers have attracted great research interest in recent decades. However, there is a lack of comprehensive understanding regarding the buildup mechanism of synchronised pulses. Here, we report a dynamic analysis of independent and synchronised solitons buildup mechanisms in synchronised ultrafast soliton lasers. The laser comprises an erbium-doped fibre cavity and a thulium-doped fibre cavity bridged with a common arm. Pulses operating at two different wavelengths formed in the cavities are synchronised by cross-phase modulation-induced soliton correlation in the common fibre arm. We find that the whole buildup process of the thulium-doped fibre laser successively undergoes five different stages: continuous wave, relaxation oscillation, quasi-mode-locking, continuous wave mode-locking and synchronised mode-locking. It is found that the starting time of the synchronised solitons is mainly determined by the meeting time of dual-color solitons. Our results will further deepen the understanding of dual-color synchronised lasers and enrich the study of complex nonlinear system dynamics.

3D error calibration of spatial spots based on dual position-sensitive detectors.

In this paper, a dual position-sensitive detector-based vision measurement system camera is built instead of a traditional CCD camera. The 3D position information for the light point is calculated according to the 2D coordinate information of a certain light point in the space illuminated on the two position-sensitive detector (PSD) photosensitive surfaces, which is used for position detection of the spatial light point. In addition, the positioning model for 2D PSDs with different spot sizes in the Gaussian spot mode is derived by the mathematical model of Lucovsky's differential equation for a PSD. For the nonlinear distortion of the PSD, a nonlinear error calibration method using a particle swarm combined with a back propagation neural network is proposed to correct the errors in the measured values through the relationship between the input and output values, to obtain the predicted value that approximates the real coordinates. Then, by comparing the influence of different spot sizes on the positioning accuracy, we conclude that the smaller the spot formed by the convergence of the beam under the optical lens, the higher the positioning accuracy. We believe this conclusion can help improve the accuracy of PSD measurements. Finally, a red LED light spot is set up, and the 3D position measurement and error calibration of the light spot is done by dual PSD cameras, which better solves the position detection problem of a space light spot under close-range conditions because it is fast, reliable, and easy to implement. It also provides an effective method to detect the motion trajectory of a moving light spot in space.

Sensing mechanism of an Au-TiO2-Ag nanograting based on Fano resonance effects.

In recent years, with the development of nano-photonics, Fano resonance has gained increasing attention. Due to its high sensitivity, real-time detection, and label-free properties, the Fano resonance sensor has been widely applied in the fields of biochemistry and environmental detection. To improve the sensing characteristics of Fano resonance, an A u-T i O 2-A g grating structure is proposed in this paper, and the sensing performance is enhanced by a bi-metallic grating and deposited T i O 2. The characteristics of both sensing and field distribution of the model are accordingly analyzed using the finite-difference time-domain method. By varying the structural parameters such as grating period, grating height, silver film thickness, and T i O 2 layer thickness, the tuning of sensing characteristics can be realized, and afterwards, the sensing performance is improved; consequently, the Fano resonance reflection spectrum with high sensitivity and a high figure of merit (FOM) value is obtained. When the grating period P = 200 nm, grating height T1 = 90 nm, silver film thickness T2 = 20 nm, T i O 2 layer thickness T3 = 20 nm, and S i O 2 layer thickness T4 = 600 nm, such a structure indicates favorable sensing performance, and sensor detection accuracy can reach 10-3; maximum sensitivity is 1400 nm/RIU, and maximum FOM can reach 4212R I U -1. The results demonstrate that the designed Fano resonance sensing model has good potential for application.

Analysis of outcomes following loop electrosurgical excision and clinical features of patients with cervical high-grade squamous intraepithelial lesions with abnormal preoperative endocervical curettage.

OBJECTIVE: The purpose of this study was to identify the clinical characteristics of patients with high-grade squamous intraepithelial lesions (HSIL) with abnormal endocervical curettage (ECC) and to evaluate the efficacy of abnormal preoperative ECC in predicting recurrence after a loop electrosurgical excision procedure (LEEP). METHODS: We retrospectively analyzed a total of 210 cases of histological HSIL in female patients diagnosed using cervical biopsy and/or indiscriminating ECC, and these included 137 cases with normal ECC and 63 cases with abnormal ECC. We also collected preoperative information and data on postoperative human papillomavirus (HPV) and histological outcomes within 2 years. RESULTS: The additional detection rate of HSIL using indiscriminating ECC was 5%. Patients with abnormal ECC were older (P < 0.001), predominantly menopausal (P = 0.001), had high-grade cytology (P = 0.032), a type 3 transformation zone (P = 0.046), and a higher proportion of HPV type 16/18 infection (P = 0.023). Moreover, age (odds ratio [OR] = 1.078, 95% confidence interval [CI] = 1.0325-1.1333, P = 0.003) and HPV 16/18 infection (OR = 2.082, 95% CI = 1.042-4.2163, P = 0.038) were independent risk factors for abnormal ECC. With an observed residual lesion/recurrence rate of 9.5% over the 24-month follow-up, we noted a 9.3% higher rate in the abnormal ECC group when compared with the normal ECC group. Abnormal preoperative ECC (OR = 4.06, 95% CI = 1.09-15.14, P = 0.037) and positive HPV at the 12-month follow-up (OR = 16.55, 95% CI = 3.54-77.37, P = 0.000) were independent risk factors for residual disease/recurrence. CONCLUSION: Preoperative ECC was one of the risk factors for post-LEEP residual/recurrent HSIL, and detecting abnormal ECC when managing older patients or patients with HPV 16/18 infection during colposcopy is critical.

A Novel Strategy for Rapid Fluorescence Detection of FluB and SARS-CoV-2.

Undoubtedly, SARS-CoV-2 has caused an outbreak of pneumonia that evolved into a worldwide pandemic. The confusion of early symptoms of the SARS-CoV-2 infection with other respiratory virus infections made it very difficult to block its spread, leading to the expansion of the outbreak and an unreasonable demand for medical resource allocation. The traditional immunochromatographic test strip (ICTS) can detect one analyte with one sample. Herein, this study presents a novel strategy for the simultaneous rapid detection of FluB/SARS-CoV-2, including quantum dot fluorescent microspheres (QDFM) ICTS and a supporting device. The ICTS could be applied to realize simultaneous detection of FluB and SARS-CoV-2 with one test in a short time. A device supporting FluB/SARS-CoV-2 QDFM ICTS was designed and had the characteristics of being safe, portable, low-cost, relatively stable, and easy to use, ensuring the device could replace the immunofluorescence analyzer in cases where there is no need for quantification. This device does not need to be operated by professional and technical personnel and has commercial application potential.

Design of a high-performance graphene/SiO2-Ag periodic grating/MoS2 surface plasmon resonance sensor.

This study optimizes a surface plasmon resonance (SPR) sensor based on SiO2-Ag periodic grating using graphene and a MoS2 hybrid structure to enhance sensitivity. The sensing performance was analyzed by wavelength modulation. By optimizing the structural parameters, we can obtain the quality factor and sensitivity of 90.192RIU-1 and 960nm⋅RIU-1. The periodic grating surface covered with MoS2 prevents the oxidation of the silver layer and increases the adsorption of biomolecules. Compared with the conventional silver grating SPR sensor, the sensor's sensitivity and quality factor can be significantly enhanced. Experiments were carried out using sucrose solutions with different refractive indices, and the results indicate there was a good linear relationship between the resonance wavelength and the sucrose solution. The sensor has vast potential for practical applications.

Double U-groove temperature and refractive index photonic crystal fiber sensor based on surface plasmon resonance.

Based on double U-groove photonic crystal fiber (PCF), a surface plasmon resonance sensor with dual parametric detection of temperature and refractive index is proposed. The birefringence of PCF is increased by using germanium ions doped in the core and introducing U-shaped notches on both sides of the D-shaped fiber. The polished surface of the PCF is coated with gold film and PDMS as a temperature sensing channel, and the U-shaped groove is coated with gold film as a refractive index sensing channel. Through the design of the sensor, it is finally possible to achieve independent measurement of the two parameters. The sensor has a maximum wavelength sensitivity of 4715 nm/RIU in the analyte refractive index range of 1.32-1.4, and maximum wavelength sensitivity of 18 nm/°C in the ambient temperature range of -30∘C-50∘C. The proposed sensor has broad application prospects in scenarios such as blood analysis, DNA hybridization analysis, and microenvironmental cell interactions.

Research on tunable distributed SPR sensor based on bimetal film.

In order to overcome the limitations in range of traditional prism structure surface plasmon resonance (SPR) single-point sensor measurement, a symmetric bimetallic film SPR multi-sensor structure is proposed. Based on this, the dual-channel sensing attenuation mechanism of SPR in gold and silver composite film and the improvement of sensing characteristics were studied. By optimizing the characteristics such as material and thickness, a wider range of dual-channel distributed sensing is realized. Using a He-Ne laser (632.8 nm) as the reference light source, prism-excited symmetric SPR sensing was studied theoretically for a symmetrical metal-clad dielectric waveguide using thin-film optics theory. The influence of the angle of incidence of the light source and the thickness of the dielectric layer on the performance of SPR dual formant sensing is explained. The finite-difference time-domain method was used for the simulation calculation for various thicknesses and compositions of the symmetric combined layer, resulting in the choice of silver (30 nm) and gold (10 nm). When the incident angle was 78 deg, the quality factor reached 5960, showing an excellent resonance sensing effect. The sensitivity reached a maximum of 5.25×10-5 RIU when testing the water content of an aqueous solution of honey, which proves the feasibility and practicality of the structure design. The structure improves the theoretical basis for designing an SPR multi-channel distributed sensing system, which can greatly reduce the cost of biochemical detection and significantly increase the detection efficiency.

Research on Straightness Error Compensation of Grating Ruling Machine.

Echelle grating is a kind of special diffraction grating. Working with high diffraction orders and big diffraction angle, which has the advantages of high resolution and full wave shining. It has been widely used in high-end spectrum instrument, which greatly promoted the development of aerospace, astronomy, medical, military, environment and other cutting-edge technology. However, professional scoring system needs to be customized, and the price is very expensive. The use of sophisticated ultra precision machining equipment to process in the ladder grating can greatly reduce the preparation cost of the mother plate of the ladder grating. Due to the bad straightness and high accumulative error of ultra precision single point diamond lathe, it can't satisfy the demand of preparation when preparing the echelle grating, casuing the bad diffraction wave front. In order to reduce the straightness error, this paper comes up with the error compensation for the single point diamond lathe. Firstly, we make the first compensation based on the accumulative error curve. When the compensation ratio is 0.75 to 0.85, the peak valley value (pv) of the diffraction wave front is about 400 nm, reaching its greatest effect of the first straightness compensation. Secondly, we make the straightness compensation according to the diffraction wave front curve of the blazed order. The pv of the diffraction wave front is about 83nm. The results show that the diffraction wave front is greatly improved which is beneficial to improve the quality of the grating, and has a guiding role in the actual grating characterization.

Prediction of Ablation Rate for High-Intensity Focused Ultrasound Therapy of Adenomyosis in MR Images Based on Multi-model Fusion.

This study aimed to develop a model based on radiomics and deep learning features to predict the ablation rate in patients with adenomyosis undergoing high-intensity focused ultrasound (HIFU) therapy. A total of 119 patients with adenomyosis who received HIFU therapy were retrospectively analyzed. Participants were included in the training and testing queues in a 7:3 ratio. Radiomics features were extracted from T2-weighted imaging (T2WI) images, and VGG-19 was used to extract advanced deep features. An ensemble model based on multi-model fusion for predicting the efficacy of HIFU in adenomyosis was proposed, which consists of four base classifiers and was evaluated using accuracy, precision, recall, F-score, and area under the receiver operating characteristic curve (AUC). The predictive performance of the combined model combining radiomics and deep learning features outperformed the radiomics and deep learning feature models alone, with accuracy of 0.848 and 0.814 in training and test sets, and AUC of 0.916 and 0.861, respectively. Compared with the base classifiers that make up the multi-model fusion model, the fusion model also exhibited better prediction performance. The fusion model incorporating both radiomics and deep learning features had certain predictive value for the ablation rate of adenomyosis under HIFU therapy and could help select patients with adenomyosis who would benefit from HIFU therapy.

Catalyzing satellite communication: A 20W Ku-Band RF front-end power amplifier design and deployment.

This paper presents a groundbreaking Ku-band 20W RF front-end power amplifier (PA), designed to address numerous challenges encountered by satellite communication systems, including those pertaining to stability, linearity, cost, and size. The manuscript commences with an exhaustive discussion of system design and operational principles, emphasizing the intricacies of low-noise amplification, and incorporating key considerations such as noise factors, stability analysis, gain, and gain flatness. Subsequently, an in-depth study is conducted on various components of the RF chain, including the pre-amplification module, driver-amplification module, and final-stage amplification module. The holistic design extends to the inclusion of the display and control unit, featuring the power-control module, monitoring module, and overall layout design of the PA. It is meticulously tailored to meet the specific demands of satellite communication. Following this, a thorough exploration of electromagnetic simulation and measurement results ensues, providing validation for the precision and reliability of the proposed design. Finally, the feasibility of that design is substantiated through systematic system design, prototype production, and exhaustive experimental testing. It is noteworthy that, in the space-simulation environmental test, emphasis is placed on the excellent performance of the Star Ku-band PA within the 13.75GHz to 14.5GHz frequency range. Detailed power scan measurements reveal a P1dB of 43dBm, maintaining output power flatness < ± 0.5dBm across the entire frequency and temperature spectrum. Third-order intermodulation scan measurements indicate a third-order intermodulation of ≤ -23dBc. Detailed results of power monitoring demonstrate a range from +18dBm to +54dBm. Scans of spurious suppression and harmonic suppression, meanwhile, show that the PA evinces spurious suppression ≤ -65dBc and harmonic suppression ≤ -60dBc. Rigorous phase-scan measurements exhibit a phase-shift adjustment range of 0° to 360°, with a step of 5.625°, and a phase-shift accuracy of 0.5dB. Detailed data from gain-scan measurements show a gain-adjustment range of 0dB to 30dB, with a gain flatness of ± 0.5dB. Attenuation error is ≤ 1%. These test parameters perfectly align with the practical application requirements of the technical specifications. When compared to existing Ku-band PAs, our design reflects a deeper consideration of specific requirements in satellite communication, ensuring its outstanding performance and uniqueness. This PA features good stability, high linearity, low cost, and compact modularity, ensuring continuous and stable power output. These features position the proposed system as a leader within the market. Successful orbital deployment not only validates its operational stability; it also makes a significant contribution to the advancement of China's satellite PA technology, generating positive socio-economic benefits.

Novel laser tracking measurement system based on the position sensitive detector.

The rapid development of modern industrial technology has led to the increase of machinery precision. Laser tracking measurement systems represent a novel type of coordinate measurement method, which was developed on the basis of metrology. In this paper, we aim to define a single-station 3D coordinate rotating laser tracking measurement system based on the principle of the space coordinate method. In view of the current architecture and optical path of the system, we establish the ideal mathematical model of the system and derive the coordinate expression for arbitrary measured points in the measurement space. The output response of the photoelectric position detector to the rotating laser and the linearity of the position signal in the detection circuit have been detected via a concrete experiment. A laser tracking system was used to track the target mirror mounted on the coordinate measuring machine measuring spindle. It is shown that stable tracking is possible during the 3D movement of a cat's eye retroreflector if its velocity is 0.2 m/s and the distance to the moving object is 1-2 m. The corresponding velocity of the object must be 0.4 m/s. Our system provides a feasible implementation method for the tracking of the moving target space position.

Weakly supervised segmentation of uterus by scribble labeling on endometrial cancer MR images.

Uterine segmentation of endometrial cancer MR images can be a valuable diagnostic tool for gynecologists. However, uterine segmentation based on deep learning relies on artificial pixel-level annotation, which is time-consuming, laborious and subjective. To reduce the dependence on pixel-level annotation, a method of weakly supervised uterine segmentation on endometrial cancer MRI slices is proposed, which only requires scribble label and is enhanced by pseudo-label technology, exponential geodesic distance loss and input disturbance strategy. Specifically, the limitations caused by the shortage of supervision are addressed by dynamically mixing the two outputs of the dual branch network to generate pseudo-labels, expanding supervision information and promoting mutual supervision training. On the other hand, considering the large difference of grayscale intensity between the uterus and surrounding tissues, the exponential geodesic distance loss is introduced to enhance the ability of the network to capture the edge of the uterus. Input disturbance strategies are incorporated to adapt to the flexible and variable characteristics of the uterus and further improve the segmentation performance of the network. The proposed method is evaluated on MRI images from 135 cases of endometrial cancer. Compared with other four weakly supervised segmentation methods, the performance of the proposed method is the best, whose mean DI, HD95, Recall, Precision, ADP are 92.8%, 11.632, 92.7%, 93.6%, 6.5% and increasing by 2.1%, 9.144, 0.6%, 2.4%, 2.9% respectively. The experimental results demonstrate that the proposed method is more effective than other weakly supervised methods and achieves similar performance as those fully supervised.

Study of Fano Resonance Effects in Graphene-Grating Composite Structures.

In order to optimize the sensitivity and detection accuracy of Fano resonance optical sensors, a sensing model of graphene-grating composite micro-nanostructure with high sensing performance is proposed based on the optical properties of graphene and grating. By studying the reflection spectra and field distribution characteristics of the structure, the sensing mechanism of Fano resonance generated by the structure is elaborated, and the parameters affecting the Fano resonance sensing performance are analyzed to enhance the Fano resonance sensing performance by optimizing the structural parameters, and the Fano resonance reflection spectral curve with high-sensitivity and high-quality factor (FOM) value is obtained. The results show that when the grating period P=300 nm, the grating height T1 = 110 nm, and the silver film thickness T2 = 30 nm, the sensitivity of the structure is 980 nm/RIU and the quality factor FOM is 770RIU-1 by changing the refractive index of the material to be measured.

High Birefringence D-Shaped Germanium-Doped Photonic Crystal Fiber Sensor.

In this work, a surface plasmon resonance (SPR) sensor based on a D-shaped germanium-doped photonic crystal fiber (PCF) is proposed. The finite element method (FEM) is introduced to analyze the structure parameters, such as germanium-doped concentration, lattice pitch, and air hole size. In addition, the coupling properties and birefringence properties of PCF are also studied. The computer simulation results indicate that two different surface plasmon polariton (SPP) coupling modes are produced on the polished surface, covered with metal film, when the analyte refractive index (RI) is 1.34. Then, with the increase of the RI, the incompleteness of one of the coupling modes will be transformed into the complete coupling. The effect of germanium concentration on the birefringence is also analyzed. It has an optimal wavelength sensitivity of 5600 nm/RIU when the RI is 1.37. This sensor exhibits a maximum birefringence of 1.06 × 10-2 and a resolution of 1.78 × 10-5 RIU with high linearity.

Cervical cell multi-classification algorithm using global context information and attention mechanism.

Cervical cancer is the second biggest killer of female cancer, second only to breast cancer. The cure rate of precancerous lesions found early is relatively high. Therefore, cervical cell classification has very important clinical value in the early screening of cervical cancer. This paper proposes a convolutional neural network (L-PCNN) that integrates global context information and attention mechanism to classify cervical cells. The cell image is sent to the improved ResNet-50 backbone network to extract deep learning features. In order to better extract deep features, each convolution block introduces a convolution block attention mechanism to guide the network to focus on the cell area. Then, the end of the backbone network adds a pyramid pooling layer and a long short-term memory module (LSTM) to aggregate image features in different regions. The low-level features and high-level features are integrated, so that the whole network can learn more regional detail features, and solve the problem of network gradient disappearance. The experiment is conducted on the SIPaKMeD public data set. The experimental results show that the accuracy of the proposed l-PCNN in cervical cell accuracy is 98.89 %, the sensitivity is 99.9 %, the specificity is 99.8 % and the F-measure is 99.89 %, which is better than most cervical cell classification models, which proves the effectiveness of the model.

Detection of deep myometrial invasion in endometrial cancer MR imaging based on multi-feature fusion and probabilistic support vector machine ensemble.

The depth of myometrial invasion affects the treatment and prognosis of patients with endometrial cancer (EC), conventionally evaluated using MR imaging (MRI). However, only a few computer-aided diagnosis methods have been reported for identifying deep myometrial invasion (DMI) using MRI. Moreover, these existing methods exhibit relatively unsatisfactory sensitivity and specificity. This study proposes a novel computerized method to facilitate the accurate detection of DMI on MRI. This method requires only the corpus uteri region provided by humans or computers instead of the tumor region. We also propose a geometric feature called LS to describe the irregularity of the tissue structure inside the corpus uteri triggered by EC, which has not been leveraged for the DMI prediction model in other studies. Texture features are extracted and then automatically selected by recursive feature elimination. Utilizing a feature fusion strategy of strong and weak features devised in this study, multiple probabilistic support vector machines incorporate LS and texture features, which are then merged to form the ensemble model EPSVM. The model performance is evaluated via leave-one-out cross-validation. We make the following comparisons, EPSVM versus the commonly used classifiers such as random forest, logistic regression, and naive Bayes; EPSVM versus the models using LS or texture features alone. The results show that EPSVM attains an accuracy, sensitivity, specificity, and F1 score of 93.7%, 94.7%, 93.3%, and 87.8%, all of which are higher than those of the commonly used classifiers and the models using LS or texture features alone. Compared with the methods in existing studies, EPSVM exhibits high performance in terms of both sensitivity and specificity. Moreover, LS can achieve an accuracy, sensitivity, and specificity of 89.9%, 89.5%, and 90.0%. Thus, the devised geometric feature LS is significant for DMI detection. The fusion of LS and texture features in the proposed EPSVM can provide more reliable prediction. The computer-aided classification based on the proposed method can assist radiologists in accurately identifying DMI on MRI.