Design of a nanoscale gold-coated photonic crystal fiber biosensor

A simple two-layer refractive index sensor based on surface plasmon resonance has been proposed in this work, which evinces high sensitivity for detecting unknown analytes. This sensor design includes hexagonal- and octagonal-shaped air-hole rings, which have been introduced in the first and second layers, respectively. By performing this amalgamation of different types of air holes, this gold-coated plasmonic sensing scheme provides the broad sensing limit of the analyte, which is 1.32–1.40. The sensing performance has been examined by applying the finite element method, which is being used for modeling complex and irregular-shaped geometry. The wavelength interrogation method has demonstrated a maximal wavelength sensitivity of 9,000 nm/RIU (refractive index unit). The maximal amplitude sensitivity of 1902 RIU−1 has been exhibited in the y-polarized mode using the amplitude interrogation method. Moreover, the maximal sensor resolution of 1.11 × 10−5 RIU covers the entire sensing range. Furthermore, by adjusting the air-hole diameter, pitch, and depth of the gold layer coating, many more investigations have been demonstrated in this design. This highly sensitive sensor is very convincing to be used in many applications like chemical, biological, and also in physical sensing analyses

Radially anisotropic ring-core optical fiber : towards vector-vortex guided transmission using the full modal space

The radially anisotropic ring-core fiber with cylindrical birefringence is theoretically and numerically investigated as a novel platform for the transmission of vector-vortex beams with unique modal properties. First, we elucidate the parametric conditions where such fiber enables modal substitution in which either the donut-shaped azimuthal TE01 or radial TM01 mode replaces the normal Gaussian-like HE11 mode as the fundamental mode of the waveguide. We also demonstrate that it is possible to significantly engineer the waveguiding properties of the fiber via the addition of small radial birefringence (~10−4 ) so as to make the (hitherto non-degenerate) TE0m and TM0m modes fully degenerate. The latter property is used to create stable vortex modes of high purity (>99%) with the newly degenerate modal pair – a feat not possible with standard few-mode fibers – all without affecting the co-propagating hybrid HE/EH modes that remain available as an independent basis set to produce vortex beams of similarly high purity. These new insights are relevant to the topical fields of mode-division multiplexing (MDM), structured light, fiber modelling and fabrication. With respect to MDM applications, the newly available vortex modes created with the degenerate TE/TM basis set can now be concurrently used with the more common vortex modes created via the HE/EH modal basis set

Performance Investigation of 1.6 Tbps Hybrid WDM-PDM-OFDM-based Free Space Optics Transmission Link

A novel ultra-high capacity free space optics (FSO) link has been developed by incorporating hybrid wavelength divison multiplexing (WDM)-polarization division multiplexing (PDM)-orthogonal frequency division multiplexing (OFDM) techniques with 16-level quadrature amplitude modulation (16-QAM) signals. Coherent detection is employed to enhance the receiver sensitivity in the presence of channel efects. The proposed link is analyzed under the impact of dynamic weather conditions viz. haze, rain, dust and fog using bit error rate, optical signal to noise ratio, error vector magnitude and maximum transmission range performance metrics. Sixteen independent DWDM channels with 0.8 nm channel spacing each carrying 100 Gbps data are successfully tranported using the proposed FSO link realizing a net data rate of 1.6 Tbps. Furthermore, we demonstrated a performance comparison of the link with contemporary works. The proposed FSO link provides a feasible and viable solution to implement ultra-high-capacity wireless transmission networks for last-mile access.A novel ultra-high capacity free space optics (FSO) link has been developed by incorporating hybrid wavelength divison multiplexing (WDM)-polarization division multiplexing (PDM)-orthogonal frequency division multiplexing (OFDM) techniques with 16-level quadrature amplitude modulation (16-QAM) signals. Coherent detection is employed to enhance the receiver sensitivity in the presence of channel efects. The proposed link is analyzed under the impact of dynamic weather conditions viz. haze, rain, dust and fog using bit error rate, optical signal to noise ratio, error vector magnitude and maximum transmission range performance metrics. Sixteen independent DWDM channels with 0.8 nm channel spacing each carrying 100 Gbps data are successfully tranported using the proposed FSO link realizing a net data rate of 1.6 Tbps. Furthermore, we demonstrated a performance comparison of the link with contemporary works. The proposed FSO link provides a feasible and viable solution to implement ultra-high-capacity wireless transmission networks for last-mile access

Photonic crystal with epsilon negative and double negative materials as an optical sensor

Two ternary photonic crystals are proposed for sensing applications. The first one is composed of an air layer as an analyte sandwiched between two double negative material (DNM) layers whereas the second one consists of an air layer sandwiched between two epsilon negative material (ENM) layers. The transmission spectrum is studied for two different values of the refractive index of the analyte layer with ∆n = 0.01. A specific peak in the transmission spectrum is observed and the wavelength at which the peak occurs is determined. The wavelength shift due to any change in the index of the analyte layer is also determined. The effect of varying the parameters of the DNM and ENM on the sensitivity of the sensor is discussed. It is found that the sensitivity of the structure ENM/air/ENM is much greater than that of the structure DNM/air/DNM and it is estimated as 26 times of the sensitivity of the latter structure

Meandered low profile multiband antenna for wireless communication applications

The compact slotted antenna having offset feed radiating in the multi-frequency bands is proposed. The antenna geometry comprises of a vertical and horizontally coupled slotted structure at the top with a complete ground plane at the bottom to achieve the proposed application bands. The patch is patterned on the FR4 substrate having a dielectric constant of 4.4 and loss tangent of 0.008. The antenna has an overall dimension of 0.18λ × 0.15λ mm2 (f = 1.52 GHz) with offset fed which is optimized to achieve 50 Ω impedance matching. The proposed compact antenna resonates in pentaband frequency bands which includes 1.52–1.60 GHz for GPS (ISM band in India), 2.97–3.02 GHz for Radio frequency identification and detection, mobile communication, logistics, manufacturing, transportation and healthcare, 3.73–3.84 GHz for Amateur Fixed Mobile except aeronautical mobile (R), 4.42–4.52 GHz for radio communications, TransferJet USB Adapter (Toshiba Corporation), and 4.83–4.96 GHz for Aviation Private Land Mobile applications. The proposed antenna has demonstrated a decent gain ranging from 1.07 to 3.92 dBi having omnidirectional and bidirectional radiation patterns, hence, making it suitable for various wireless applications

تصميم بلورة ضوئية أحادية البعد قائمة على عيوب مع مكونات مواد فائقة التوصيل لتطبيقات الاستشعار الحيوي

A novel biosensor based on 1-D defect photonic crystal is suggested to be consisting of alternate layers of SiO2 and Air. At the middle, there exists a cavity layer encapsulated with a composite layer of superconducting and dielectric materials. The blood samples are infiltrated in the cavity. The sensitivity is calculated at different parameters including filling factor of superconducting materials, the temperature, and the width of the cavity. Results indicate that the sensitivity decrease slightly as temperature increases and sensitivity increases as filling factor increases and thickness of cavity increases.A novel biosensor based on 1-D defect photonic crystal is suggested to be consisting of alternate layers of SiO2 and Air. At the middle, there exists a cavity layer encapsulated with a composite layer of superconducting and dielectric materials. The blood samples are infiltrated in the cavity. The sensitivity is calculated at different parameters including filling factor of superconducting materials, the temperature, and the width of the cavity. Results indicate that the sensitivity decrease slightly as temperature increases and sensitivity increases as filling factor increases and thickness of cavity increases

Graphene oxide-based optical waveguide for moisture sensing in transformer oil

We report on moisture detection in transformer oil based on an optical waveguide fabricated using graphene oxide (GO). The SU-8 polymer channel waveguide was coated by GO film, using a drop-casting technique. Here, for the polarized light, high absorption of transverse electric (TE) was achieved for the proposed sensor at wavelength 1550 nm. Changes in TE-polarized light absorption by the device were measured at varying water contents. Experiments were carried out for water contents in oil in the range of 16–21 ppm as well as immiscible (free) water in oil. Our observations showed a difference in the results trend obtained for different relative water contents. The TE-transmission power increased linearly with higher water content in transformer oil. A power change of +0.90 dB/ppm of water content in transformer oil was measured within the range tested. A simulation analysis using the finite element method FEM was also carried out. The proposed sensing mechanism can be used under these sensing conditions. This approach also has a fast response time as well as high sensitivity. © 2019 Elsevier B.V

Materials Effect in Sensing Performance Based on Surface Plasmon Resonance Using Photonic Crystal Fiber

This article explores the effect of sensing performances with subject to change in different types of material and this study is carried out by the support of plasmon-coated photonic crystal fiber (PCF). Three different materials gold, niobium, and doping materials (niobium and Al2O3) have been used as sensing materials to find out the best performance of the raised structure. Each material deposited sequentially on the PCF surface and the structural characterization is analyzed by finite element method (FEM).The investigation shows that it can provide the enhanced wavelength sensitivity of 5000 nm/RIU, 8000 nm/RIU, and 10,000 nm/RIU; and amplitude sensitivity of 171 RIU−1, 188 RIU−1, and 249 RIU−1 for gold, niobium, and doping materials, respectively, at analytes 1.37 and 1.38. In both cases, doping materials show best outcome. Moreover, the proposed model is also investigated to detect the change of phase matching point with the variation of center air hole diameter. The obtained results ensure that it may be helpful for any chemical or biological analytes detection. © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Nano-Engineered HfO2-Au photonic sensor for ultra-sensitive refractive index detection

In this study, we introduce a novel hafnium dioxide (HfO2) and thin gold layer based photonic crystal fiber (HfAu-PCF) sensor for refractive index measurement and optimize in the spectrum of 1.3 µm to 1.6 µm. The proposed sensor incorporates a D-shaped geometry for enhanced light-matter interaction, and the core of the fiber is surrounded by periodic air holes to facilitate efficient coupling of the guided mode with surface plasmons. The proposed HfAu-PCF sensor is geometrically optimized using finite element method (FEM) by fine-tuning air hole diameter, core size, layer thickness dimensions of the fiber to achieve performance stability. Leveraging the unique optical properties of HfO2 and Au, the sensor demonstrates superior performance metrics, achieving confinement loss (<10−6 dB/m), propagation constant (β) ∼ 6 × 106, V-Parameter < 2.3, a peak relative sensitivity of 99.05 % across the tested wavelength of 1.3 µm to 1.6 µm. Our findings reveal that choosing suitable parameters could lead to further enhancements in sensitivity, making the sensor for applications in bio-sensing, environmental monitoring, and chemical analysis, etc