This study proposes a novel, highly sensitive surface plasmon resonance (SPR) sensor based on a hexagonal photonic crystal fibre (PCF) sensor, tailored for analytes' refractive index (RI) detection from 1.30 to 1.43. The sensor's optical characteristics are analysed using finite element method (FEM) simulations. The proposed design achieves a peak wavelength sensitivity of 29,000 nm/RIU and an amplitude sensitivity of 2,653.68 RIU-& sup1;. Additionally, a high resolution of 3.45 & times; 10(-)(6) RIU underscores its effectiveness in capturing minute variations in refractive index. We conducted a comparative evaluation of ten machine learning algorithms for predicting confinement loss and amplitude sensitivity. Our results show that ensemble methods, particularly Extra Trees, Random Forest, Gradient Boosting, and XGBoost, achieve exceptionally high prediction accuracy for confinement loss (R-2 > 0.999), while LightGBM outperforms other models for amplitude sensitivity prediction (R-2 = 0.9448). The proposed sensor is stable and suited for detecting analytes for food safety, and adulteration monitoring applications.

The continued performance scaling of AI gigafactories requires the development of energy-efficient devices to meet the rapidly growing global demand for AI services. Emerging materials offer promising opportunities to reduce energy consumption in such systems. In this work, we propose an electro-optic microring modulator that exploits a graphene (Gr) and transition-metal dichalcogenide (TMD) interface for phase modulation of data-bit signals. The interface is configured as a capacitor composed of a top Gr layer and a bottom WSe2 layer, separated by a dielectric Al2O3 film. This multilayer stack is integrated onto a silicon (Si) waveguide such that the microring is partially covered, with coverage ratios varying from 10% to 100%. In the design with the lowest power consumption, the device operates at 26.3 GHz and requires an energy of 5.8 fJ/bit under 10% Gr-TMD coverage while occupying an area of only 20 μm2. Moreover, a modulation efficiency of VπL = 0.203 V·cm and an insertion loss of 6.7 dB are reported for the 10% coverage. The Gr-TMD-based microring modulator can be manufactured with standard fabrication techniques. This work introduces a compact microring modulator designed for dense system integration, supporting high-speed, energy-efficient data modulation and positioning it as a promising solution for sustainable AI gigafactories.

In bus-based sensing, public transport serves as a mobile urban sensing platform. While offering much higher geographical coverage, the low-cost sensors mounted on vehicles can be less accurate and demand more frequent calibration, which may be challenging for large vehicle fleets. As calibration is performed by relating mobile sensor readings to those of fixed reference stations, the placement of reference stations is very important. In this work, we propose an algorithm for computing the optimal locations for reference stations to maximize the sensing coverage. Contrary to prior work, coverage is defined in terms of geographical area, extending a certain distance away from the route trajectory, which represents the actual sensing capacity of the vehicles. The proposed algorithm computes it using geographical set operations, such as spatial join and subtraction to compute the unique contribution of each bus route. We evaluate the approach using real bus trajectories from Manhattan, USA, and compare it with a random baseline and prior work. The results indicate that given the bus routes, a complete sensing coverage can be achieved using a single reference station with a maximum 2-hop calibration path.

In this article, we explore the use of gradient-based optimization algorithms for automated bias control in Mach-Zehnder modulators (MZMs). We present and demonstrate, experimentally, five gradient descent (GD) algorithms-stochastic GD (SGD), SGD with momentum (SGD+M), Adagrad, RMSProp, and Adam-applied to the bias control problem in MZMs. We present a method of creating an error signal from the measured output of an MZM with a low-frequency pilot tone and provide a detailed explanation of how each algorithm is used to both identify the set bias condition and track the bias condition in the presence of disturbances. Our implementation is capable of identifying and holding the null condition and the quadrature condition. We evaluate the bias point identification for each algorithm by measuring and analyzing the step response for each method. We test the bias tracking of each algorithm using three forms of disturbance-radio frequency (RF) power disturbances, temperature disturbance, and long-term bias drift. All tests were conducted at 20 GHz. To the best of our knowledge, this is the first investigation into the application on gradient-based learning approaches for MZM bias control. This work has great importance on future bias control design and implementations for telecommunications, the space sector, microwave photonics (MWPs), and defense.

6G systems are expected to operate in the THz band to support ultra-high data rates. However, severe propagation impairments in THz channels pose significant challenges. This paper presents a new channel model and numerical analysis of a THz system using orthogonal chirp division multiplexing (OCDM). The system includes chirped waveforms at 300 GHz, minimum mean square error (MMSE) equalization, amplitude modulation, and three ray-tracing-derived indoor environments: spacious hall, long corridor, and empty room. Results show OCDM enhances resilience to multipath effects, especially for lower-order modulations. The findings highlight OCDM with environment-aware techniques as a robust solution for future THz communications.

Driven by the global growth in AI services, the demand for efficient hardware is at an all-time high in the race for continued performance scaling of hyperscale data centers. Integrated photonics devices have emerged as a promising alternative for reducing energy consumption. We report an optical modulator design that incorporates chalcogenide and graphene materials to achieve the minimal power consumption per bit during high-speed operation. The device design and its energy consumption performance are presented. Our results pave the way for ultra-efficient modulators revealing operations at high-speed modulation bandwidth up to 104 GHz whilst reducing energy consumption to 52.3 fJ/bit.

In this article, we report a frequency-tunable, suppression depth-tunable, narrow microwave photonic (MWP) notch filter based on the state of polarization (SOP) control of stimulated Brillouin scattering (SBS) in SMF. SBS gain is highly dependent on the SOPs of the pump-and-probe signals with a maximum gain when their SOPs are the same, and a minimum when they are orthogonal to one another. We exploit this phenomenon to create a tunable depth notch filter by adjusting the gain and loss of SBS for radio frequency (RF) cancellation with a photodiode. We develop and present a mathematical model explaining the polarization-dependent gain and the transfer function of the proposed filter. Experimental results demonstrate a tunable notch filter with a notch depth tuning range of 0-40 dB with a frequency range of 2-26.5 GHz. The -3 dB width of the filter was recorded as 37 MHz at its maximum depth, with a low 4 MHz recorded in shallower notches. The notch depth is tuned by a polarization controller that controls the SOP of the pump signal. This configuration has applications in dynamic notch filtering of signals such as RF interference (RFI) removal where control over the notch depth is of great importance. The proposed tunable depth notch filter would provide unique benefits for satellite, aerospace, telecommunications, and beyond communication technologies.

Nowadays, early cancer identification and surveillance have become vital problems. This research paper explores the development of a small, three-band sensor harnessing the potential of terahertz (THz) technology and metamaterials (MTMs) to diagnose blood cancer. The proposed sensor holds the promise of a paradigm shift in the diagnosis of blood cancer by offering a non-invasive and highly accurate approach. Terahertz radiation, occupying the unique “THz gap” in the electromagnetic spectrum, is now accessible due to recent technological breakthroughs. This work simplifies the design of multiple-band metamaterial absorbers, enhancing their effectiveness and expanding their sensing capabilities. Through the integration of THz technology, metamaterial engineering, and cancer detection, the suggested sensor seeks to launch a new phase of rapid, precise, and non-invasive blood cancer diagnosis. The proposed structure is capable of distinguishing cancer and normal cell with 1 GHz sensitivity, which would be more pronounced when we consider the THz technology devices. This work represents a significant step forward in non-invasive, accurate diagnostics for blood cancer, promising to revolutionize the way this disease is diagnosed and treated. The proposed novel strategy has a lot of promise to advance medical diagnostics and enhance patients’ outcomes.

Pulse oximeters are widely used in hospitals and homes for measurement of blood oxygen saturation level (SpO2) and heart rate (HR). Concern has been raised regarding a possible bias in obtaining pulse oximeter measurements from different fingertips and the potential effect of skin pigmentation (white, brown, and dark). In this study, we obtained 600 SpO2 measurements from 20 volunteers using three UK NHS-approved commercial pulse oximeters alongside our custom-developed sensor, and used the Munsell colour system (5YR and 7.5YR cards) to classify the participants’ skin pigmentation into three distinct categories (white, brown, and dark). The statistical analysis using ANOVA post hoc tests (Bonferroni correction), a Bland–Altman plot, and a correlation test were then carried out to determine if there was clinical significance in measuring the SpO2 from different fingertips and to highlight if skin pigmentation affects the accuracy of SpO2 measurement. The results indicate that although the three commercial pulse oximeters had different means and standard deviations, these differences had no clinical significance.

Abstract Background and aims Recent studies have suggested that diabetes patients with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) may experience a reduced incidence of appropriate ICD-shocks and an increased mortality rate. This study aims to assess whether there is parity in ATP-treatment and ICD-shocks between patients with and without type 2 diabetes mellitus (T2DM), and to analyze associated mortality rates. Methods Using the Danish pacemaker and ICD registry we included patients who received a first-time ICD or CRT-D implantation with a primary or secondary prophylactic indication, between January 1st 2000 to December 31st 2018. Outcomes were analyzed individually for each outcome. Cause specific Cox was used for i) appropriate ATP therapy or ICD-shock, ii) inappropriate ATP therapy or ICD-shock, and a standard Cox regression model was used for iii) all-cause mortality, iv) mortality rate following an ATP-therapy or ICD-shock. Cumulative incidence curves, generated using the Aalen Johansen estimator, were utilized to compare the incidence rates for ATP therapy and ICD-shock while accounting for competing risk of death, while Kaplan-Meier methodology was utilized for survival curves. Analyses were conducted in the total population and in subgroups divided on indication and device type. Results Out of 14 747 patients who received an ICD or CRT-D, 4377 (30%) had T2DM, 4593 (31%) patients received first-time appropriate ATP therapy or ICD-shock, and 1244 (8,4%) experienced first-time inappropriate treatments, 5 112 (35%) experienced death during the follow-up time (mean 3.9 years (SD 2.7)). T2DM patients were more likely to be male (85% vs 80%), slightly older (66 vs 65 years) and burdened with more comorbidities. No significant differences were seen between T2DM and non-T2DM patients for appropriate ATP therapy (HR 0.96[0.88:1.04] p=0.31), appropriate ICD-shock (HR 0.95[0.86:1.05] p=0.32), inappropriate ATP therapy (HR 0.92 [0.77;1.09] p=0.32) and inappropriate ICD-shock (HR 0.96 [0.78;1.18] p=0.71). In the subgroup analyses, no difference was seen in the primary prophylactic subgroups (Figure 1.), only significant difference was observed in the secondary prophylactic ICD group who received less ATP-therapy at 5-year follow-up (HR0.83[0.70;0.99] p=0.04), and in the secondary prophylactic CRT-D group, were T2DM patients seemed to experience more appropriate ICD-shock treatments (HR 2.07[1.23;3.48] p=0.006). Further, we found a higher mortality rate in T2DM with primary prophylactic ICD (HR 1.46[1.31;1.62] p<0.001) and secondary prophylactic ICD (HR 1.30[1.13;1.51] p<0.001), (Figure 2.) this mortality rate remained largely unchanged post appropriate ATP or ICD-shock in the ICD subgroups. Conclusions Despite similar incidence of ATP-therapy and ICD-shocks, T2DM patients with ICD-device experienced a significantly higher post-treatment mortality and all-cause mortality rate.

Bone tumours are a complex group of pathological conditions that can occur in any region of the bones and are classified as benign or malignant. Osteosarcoma is the most common primary bone malignancy and is divided into three subdivisions: osteoblastic, chondroblastic and fibroblastic. Osteosarcoma is usually seen at an early age, while another type is more common in the elderly. Imaging techniques are of great importance in the diagnosis and treatment of bone tumours. Techniques such as X-ray, magnetic resonance imaging, computed tomography and positron emission tomography are among the methods used in the detection of bone tumours. In recent years, microwave and antenna-based technologies have been reported to play a potential role in the imaging of bone tumours. Microwave-based antennas can perform non-invasive imaging using the interaction of electromagnetic waves on cancer cells. In this study, we designed a non-invasive mathematically supported antenna and tested this antenna on a clinically suitable tibia bone and tumour phantom. The results proved that bone tumour can be detected non-invasively with microwave antennas.

The operating wavelength and modulation frequencies are the critical components of every communication system. Here, we present a speckle pattern (SP) fiber-based spectrometer using a nominally fixed 852-nm laser to measure and calibrate the wavelength and modulation frequencies of the SP produced in multimode fiber (MMF). The laser wavelength is finely tuned within the 100 GHz range and at a resolution of 2 pm (picometers) by appropriately varying the laser injection currents. The wavelength-dependent SP is calibrated by varying the laser current over a preset range, and a series of wavelength-dependent SP data are recorded. The laser is tuned to the middle of the recorded wavelength range for the modulation frequency calibration, and a standard lithium niobate (LiNbO3) electrooptic modulator Mach-Zehnder modulator (MZM) is applied. With ten meters of MMF, the incoming radio frequency (RF) is modulated in 5 GHz steps up to 40 GHz at a constant wavelength of 852.555 nm, and the generated SPs are stored separately for spectral processing and training. The wavelength-dependent SPs are trained using artificial intelligence (AI), with a reported prediction accuracy of 98.7% at 2-pm wavelength resolution. To the best of our knowledge, this is the first proof-of-concept of a high-resolution, low-cost SP AI-based spectrometer (SPAIS) that has been experimentally reported to predict the exact values of modulated frequencies from the modulated SPs.

Stimulated Brillouin scattering (SBS)-based filters can provide high gain, narrow bandwidth, and wideband tunability, which are critical to modern radio frequency (RF) systems. However, it is important to optimize all performance parameters to obtain stable response over wideband along with high gain. We present a novel SBS-based tunable microwave photonic notch filter and amplifier (TMWPNFA) configuration that can perform notch filtering, selective amplification, or both simultaneously by exploiting additional Brillouin gain modes and using both SBS stokes and antistokes in single-mode fiber. The TMWPNFA amplification and notch suppression are shown for maximum of 50 GHz in radio domain, which is the highest reported tunability to our knowledge. The TMWPNFA exhibits high gain of similar or equal to 35 dB by employing RF amplifier (RFA). The TMWPNFA achieves SBS gains from 24 to 4 dB over the range. The suppression achieved by TMWPNFA ranges from 12 to 3 dB. We demonstrated the SBS pump's RF mixing approach for increasing the -3 dB bandwidth of TMWPNFA to 35 MHz, resulting in greater separation of the amplification and suppression bands. The TMWPNFA phase noise distortion caused by SBS is measured to be less than -8.6 dBc/Hz at 125 kHz spacing. The filter achieved sharp -3 dB bandwidth of 20 MHz and Q factor of 200-2500. The degree of polarization of the SBS pump is shown to be the source of 6 dB gain control. It is shown that additional sound modes produced by SBS, separated by approximately two times bandwidth of SBS, can be used for notch filtering while simultaneously achieving selective amplification. The proposed 50 GHz TMWPNFA would provide unique benefits for satellite, aerospace, and beyond communication technologies.

This paper proposes a Hexagonal Circular Photonic Crystal Fiber (HC-PCF) with uniform tiny air holes around the core, obtaining ultra-high negative dispersion, high Birefringence and low confinement loss. The modal properties of the HC-PCF are investigated using the full-vectorial-Finite Element Method (FEM) with a perfectly matched layer as the boundary condition. The numerical investigations show ultra-high negative dispersion of -25503 ps/nm.km, a birefringence of 1.36 x 10-2, a nonlinearity of 38.34w- 1km- 1 and a confinement loss of 4.95 x 10-3 dB km- 1 at the wavelength of 1550 nm. Moreover, the proposed HC-PCF exhibits a high negative dispersion and multiple Zero Dispersion within the 800 to 2000 nm wavelengths range. Specifically, the high negative dispersion, low optical Confinement Loss, and multiple Zero Dispersion Wavelengths (ZDW) give the proposed HC-PCF high Power Spectral Density (PSD). These characteristics make the proposed fibre suitable for long-range telecommunication networks and optical sensing.

In this study, a biosensor based on a central microring comprising miniature gold rings is reported for the detection of influenza avian viruses. The label-free microring resonator's design performance attributes as a function of the host analytes (viral samples) enable great sensitivity for detecting various viruses, such as H1N1 and H9N2. The microring resonator's optimised char-acteristics make the suggested biosensor sensitive to these viruses. The simulations show a sensitiv-ity of 880 nm/RIU for H1N1 and around 2025 nm/RIU for H9N2. The use of two-dimensional black phosphorus materials with higher field enhancement, biocompatibility, and a greater surface-to-volume ratio resulted in a significant increase in sensitivity of 1425 nm/RIU for detecting H9N2. The sensor is proven to be more sensitive to H9N2 than H1N1. Furthermore, the biosensor based on 2D material has a compact footprint and a larger wavelength shift for H9N2, which can accelerate the development of nano optic biosensors for rapid, sensitive, and early detection of viruses.Crown Copyright & COPY; 2023 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Abstract Introduction Type 2 diabetes mellitus (T2DM) is associated with third-degree atrioventricular block, but whether duration of T2DM is an important factor of the association is unknown. Aim To investigate the association between duration of T2DM and third-degree atrioventricular block. Method This nested case–control study, based on nation-wide Danish cohort registries, included patients older than 18 years, diagnosed with third-degree atrioventricular block between 1 July 1995 and 31 December 2018. Five controls, from the risk set of each case of third-degree atrioventricular block, were matched on age and sex to fit a conditional logistic regression with time-dependent exposure and time-dependent covariates. Duration of T2DM was split into four groups: 0–5 years, 6–10 years, 11–15 years, and >15 years. Results We included 24 177 cases with third-degree atrioventricular block who were matched 1:5 on sex and birth year with 120 915 controls without third-degree atrioventricular block. Median age was 73.8 years, 62% were males in both cases and controls, whereas 19% of cases and 9.7% of controls had T2DM respectively. After adjusting for atrioventricular nodal blocking agents and comorbidities known to be associated with third-degree atrioventricular block, patients with T2DM duration 0–5 years, 6–10 years, 11-15 years, and >15 years had a higher hazard ratio of third-degree atrioventricular block of 1.24 (95% CI 1.16-1.33), 1.41 (95% CI 1.31-1.52), 1.79 (95% CI 1.64-1.95), and 2.20 (95% CI 2.01-2.40), respectively, compared to patients with no T2DM (Figure 1). Conclusion This study shows a stepwise increase in the hazard ratio of third-degree atrioventricular block along with duration of T2DM, which is independent of atrioventricular nodal blocking agents and comorbidities known to be associated with third-degree atrioventricular block.Figure 1

In this study, the coupling and the relative sensitivity characteristics of a Dual-Core photonic crystal fiber (DC-PCF)-based liquid sensor are evaluated by employing the full-vectorial finite element method (FV-FEM). The simulation results demonstrate that coupling length of the proposed sensor varies between 2[Formula: see text]mm and 0.2[Formula: see text]mm length at wide wavelength range (800–1600[Formula: see text]nm) for low index analytes (1.33–1.36). Besides, birefringence of order [Formula: see text] is reported. It is found that analyte with 1.36 index reaches higher sensitivity levels. On the other hand, the coupling length of the proposed sensor can be optimized with the ellipticity ratio of the central core hole. Bending analysis on coupling length and optical power fluctuations is also reported. It is found that the power flow in one core is increasing almost 90% towards the bending direction. The proposed structure with simple design parameters has a great potential in various biomedical applications including DNA detection and can also be employed as fiber-based refractometer in various sensing applications.

This article presents the design and implementation of an Internet of Things (IoT)-based remote health monitoring system for the estimation of blood pressure (BP), heart rate (HR), and blood oxygen saturation levels (SpO(2)). Our designed sensor can remotely monitor BP, HR, and SpO2. Our device collects, evaluates, predicts, and reads health data and then stores it on a remote platform named "ThinkSpeak, " which forms an IoT platform, with a 0.91 organic light-emitting diodes (OLEDs) screen display for viewing numerical health readings locally. We used a biomedical sensor device with an embedded signal condition unit, and a single photoplethysmography (PPG) signal was employed to derive and measure the PPG signal. A computer-based algorithm was generated, which factored in selected beneficial parameters measured from a single bio-inspired PPG signal. The measured PPG signal was used to estimate the individual user's BP (both systolic and diastolic values), HR, and SpO2. An automatic multiscale-based peak (AMBP) detection algorithm was developed to obtain the maximum peak of the PPG signal. Furthermore, the developed sensor was benchmarked against two standard commercially available measurement devices: a Contec ambulatory BP sensor and a Braun pulse oximeter monitor. Our developed sensor is worn as a ring sensor and is interfaced with an Arduino 1010 WIFI MKR for remote health monitoring. Our estimated BP, HR, and SpO2 values were remotely monitored and a graphical representation was constructed.

Cybersecurity and cyber resilience are becoming crucial for many industries especially in the era of digital transformation. In this work, we report on the security analysis of the physical layer of OCDMA networks based on 2-D codes such as fast frequency-hopping (FFH). We analyze eavesdropping in OCDMA networks using FFH codes spread in both, time and frequency domains that use quadrature phase-shift keying (QPSK). The analysis is based on a newly derived bit error rate (BER) formula considering the eavesdropper’s partial knowledge of the 2-D code that is needed to replicate the ONU decoder. An analytical formalism for evaluating the BER performance of the network is derived by considering 2-D codes, QPSK modulation format, avalanche photodiode shot noise, thermal noise, and multiple-access interference among optical network units (ONUs). Numerical results show that the intercepted signal is hard to decode and the information retrieved when the eavesdropper makes more than one error in guessing the used ONU code. It is shown the number of simultaneous ONUs substantially affects the eavesdropper’s capability to decode the intercepted signal. The novel 2-D FFH signal encoding is robust against the eavesdropper interception. It offers a feasible solution to increase security levels in practical optical networks.

Abstract Capacity crunch has become critical in recent years as commercial communication systems approach their theoretical data rate limits. This work presents a low‐complexity digital backpropagation (DBP) implementation approach based on step size distribution that uses a binary logarithmic step size method to achieve high data rate optical transmission. The proposed scheme shows performance improvements (∆Q) of 2.36, 1.19, and 0.71 dB over linear compensation, constant step size (CSS) DBP, and logarithmic step size DBP techniques in a 2400 km 112 Gbit/s DP‐16 quadrature amplitude modulation (QAM) system, respectively. At 13 dBm, a high performance (Q) of 10.9 dB (BER = 2.25 × 10−4) is achieved, above the 3.80 × 10−3 hard‐decision forward error correction (HD‐FEC) limit, using the proposed scheme. Also, the allowable transmission distance is extended by 960 km at the HD‐FEC limit over the linear compensation technique. The optimization achieves a 38% saving in the number of DBP calculation steps compared to the CSS DBP, which considerably reduces the computational cost since a few steps are required for effective non‐linearity compensation.