Effect of Skin Pigmentation and Finger Choice on Accuracy of Oxygen Saturation Measurement in an IoT-Based Pulse Oximeter.

Pulse oximeters are widely used in hospitals and homes for measurement of blood oxygen saturation level (SpO) 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 SpO 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.

Beyond 5G Fronthaul Based on FSO Using Spread Spectrum Codes and Graphene Modulators.

High data rate coverage, security, and energy efficiency will play a key role in the continued performance scaling of next-generation mobile systems. Dense, small mobile cells based on a novel network architecture are part of the answer. Motivated by the recent mounting interest in free-space optical (FSO) technologies, this paper addresses a novel mobile fronthaul network architecture based on FSO, spread spectrum codes, and graphene modulators for the creation of dense small cells.

Elimination of odd and even intermodulation distortions of analog microwave photonics link based on GaAs MZMs.

In this paper, a high linear Analogue Microwave Photonic Link (AMPL) is proposed and experimentally demonstrated by unique ways of deploying Gallium Arsenide (GaAs), two Electro-optic Mach-Zehnder Modulators (MZMs), and Balanced Photo detector (BPD). All even and odd intermodulation distortions products are suppressed under noise floor. Second Order Harmonics (SOH) are also significantly suppressed by careful arrangements of microwave shifters and MZMs.

Neuro-rehabilitation service during COVID-19 pandemic: Best practices from UK.

This paper provides the context of COVID-19 outbreak with special reference to hospital-based neurorehabilitation services in the UK and transferrable lessons for similar services globally. While the COVID-19 pandemic has created numerous challenges at all levels and forced us to confront our own vulnerabilities as individuals, teams, services, communities and on the global stage, it has also simultaneously offered us opportunities for transformation. Converting catastrophe into opportunity requires creativity, diligence, innovation, strategy and vision.

2D/3D graphene on h-BN interlayer-silicon solar cell with ZnO:Al buffer layer and enormous light captivation using Au/Ag NPs.

In this paper, systematic design and analysis of thin-film graphene-silicon solar cells with the addition of an anti-reflection coating (ARC), hexagonal boron nitride (h-BN) interlayer and decorated with Au/Ag NPs infused in rear ZnO:Al buffer layer is reported. The 3D NPs are located on the top and rear side of the solar cell. Initially, we simulated a reference 2D graphene-silicon solar cell with highest simulated short circuit current density (Jsc) 30mA/ cm and power conversion efficiency (PCE) of 10.

PCF Based Sensor with High Sensitivity, High Birefringence and Low Confinement Losses for Liquid Analyte Sensing Applications.

In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF) sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM) simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures.

Light field geometry of a Standard Plenoptic Camera.

The Standard Plenoptic Camera (SPC) is an innovation in photography, allowing for acquiring two-dimensional images focused at different depths, from a single exposure. Contrary to conventional cameras, the SPC consists of a micro lens array and a main lens projecting virtual lenses into object space. For the first time, the present research provides an approach to estimate the distance and depth of refocused images extracted from captures obtained by an SPC.

Optimization of compact lateral, vertical, and combined tapered spot-size converters by use of the beam-propagation method.

A study of lateral, vertical, and combined spot-size converters is presented that employs full-vectorial numerical techniques such as modal solution and beam propagation based on the finite-element method. Spot-size expansion, coupling efficiency to an optical fiber, the mode-beating phenomenon, and transmission losses are demonstrated for all three spot-size-converter designs. Optimization of the device fabrication parameters is also reported.

Numerical modeling of polarization conversion in semiconductor electro-optic modulators.

An accurate numerical simulation study of a polarization conversion phenomenon in deeply etched semiconductor electro-optic waveguide modulators is presented. Based on a powerful and versatile finite element package, the effect of various imperfect fabrication conditions on unwanted and unexpected polarization conversion in electro-optic semiconductor modulators is, for the first time to our knowledge reported and explained in terms of its origin.

Velocity matching of a GaAs electro-optic modulator.

New designs for the velocity matching of a deep-etched semiconductor electro-optic modulator are presented. A tantalum pentoxide (Ta2O5) coating is considered here for achieving velocity matching between the microwave and the optical signals. The effects of the velocity mismatch, the conductor loss, the dielectric loss, and the impedance mismatch are studied in relation to the optical bandwidth of a high-speed semiconductor modulator.

Bandwidth estimation for ultra-high-speed lithium niobate modulators.

The effects of velocity matching, impedance matching, conductor loss, and dielectric loss on the optical bandwidth of an ultra-high-speed lithium niobate modulator are reported. It is shown that both dielectric loss and impedance matching play a key role for velocity-matched high-speed modulators with low conductor loss. The effects of etch depth, buffer thickness, electrode width, and thegap between the electrodes on device performance are also illustrated.