Faisal Rafiq Mahamd Adikan

Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor with Selective Analyte Channels and Graphene-Silver Deposited Core

We propose a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) with selectively filled analyte channels. Silver is used as the plasmonic material to accurately detect the analytes and is coated with a thin graphene layer to prevent oxidation. The liquid-filled cores are placed near to the metallic channel for easy excitation of free electrons to produce surface plasmon waves (SPWs). Surface plasmons along the metal surface are excited with a leaky Gaussian-like core guided mode. Numerical investigations of the fiber’s properties and sensing performance are performed using the finite element method (FEM). The proposed sensor shows maximum amplitude sensitivity of 418 Refractive Index Units (RIU−1) with resolution as high as 2.4 × 10−5 RIU. Using the wavelength interrogation method, a maximum refractive index (RI) sensitivity of 3000 nm/RIU in the sensing range of 1.46–1.49 is achieved. The proposed sensor is suitable for detecting various high RI chemicals, biochemical and organic chemical analytes. Additionally, the effects of fiber structural parameters on the properties of plasmonic excitation are investigated and optimized for sensing performance as well as reducing the sensor’s footprint.

Serological Diagnosis of Dengue Infection in Blood Plasma Using Long-Range Surface Plasmon Waveguides

We present a compact, cost-effective, label-free, real-time biosensor based on long-range surface plasmon polariton (LRSPP) gold (Au) waveguides for the detection of dengue-specific immunoglobulin M (IgM) antibody, and we demonstrate detection in actual patient blood plasma samples. Two surface functionalization approaches are proposed and demonstrated: a dengue virus serotype 2 (DENV-2) functionalized surface to capture dengue-specific IgM antibody in blood plasma and the reverse, a blood plasma functionalized surface to capture DENV-2. The results obtained via these two surface functionalization approaches are comparable to, or of greater quality, than those collected by conventional IgM antibody capture enzyme linked immunosorbent assay (MAC-ELISA). Our second functionalization approach was found to minimize nonspecific binding, thus improving the sensitivity and accuracy of the test. We also demonstrate reuse of the biosensors by regenerating the sensing surface down to the virus (or antibody) level or down to the bare Au.

Rapid Immunoglobulin M-Based Dengue Diagnostic Test Using Surface Plasmon Resonance Biosensor

Surface plasmon resonance (SPR) is a medical diagnosis technique with high sensitivity and specificity. In this research, a new method based on SPR is proposed for rapid, 10-minute detection of the anti-dengue virus in human serum samples. This novel technique, known as rapid immunoglobulin M (IgM)-based dengue diagnostic test, can be utilized quickly and easily at the point of care. Four dengue virus serotypes were used as ligands on a biochip. According to the results, a serum volume of only 1 μl from a dengue patient (as a minimized volume) is required to indicate SPR angle variation to determine the ratio of each dengue serotype in samples with 83–93% sensitivity and 100% specificity.

Efficient, Wide Angle, Structure Tuned 1

We propose a wide angle, efficient and low loss 1 × 3 power splitter based on triangular lattice air holes silicon slab Photonic Crystal (PhC). Desired power splitting ratio was achieved by altering the structure at the junction area of the power splitter. Simulation results obtained using 2-D finite difference time domain method show that for TE polarization incident signal, the power is distributed almost equally with total normalized transmission of 99.74% and negligible reflection loss at the 1550 nm optical operating wavelength. In addition, the power splitter can operate at 1388 nm and 1470 nm optical wavelengths.

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A method for improving the thermoluminescence (TL) yield of silica-based optical fibres is demonstrated. Using silica obtained from a single manufacturer, three forms of pure (undoped) fibre (capillary-, flat-, and photonic crystal fibre (PCF)) and two forms of Ge-doped fibre (capillary- and flat-fibre) were fabricated. The pure fibre samples were exposed to 6 and 21MeV electrons, the doped fibres to 6MV photons. The consistent observation of large TL yield enhancement is strongly suggestive of surface-strain defects generation. For 6MeV irradiations of flat-fibre and PCF, respective TL yields per unit mass of about 12.0 and 17.5 times that of the undoped capillary-fibre have been observed. Similarly, by making a Ge-doped capillary-fibre into flat-fibre, the TL response is found to increase by some 6.0 times. Thus, in addition to TL from the presence of a dopant, the increase in fused surface areas of flat-fibres and PCF is seen to be a further important source of TL. The glow-curves of the undoped fibres have been analysed by computational deconvolution. Trap centre energies have been estimated and compared for the various fibre samples. Two trap centre types observed in capillary-fibre are also observed in flat-fibre and PCF. An additional trap centre in flat-fibre and one further trap centre in PCF are observed when compared to capillary fibre. These elevated-energy trap centres are linked with strain-generated defects in the collapsed regions of the flat fibre and PCF.

3 Photonic Crystal Power Splitter at 1550 nm for Triple Play Applications

High average gains of greater than 31 dB have been obtained between 1530-1560 nm (conventional-wavelength band, C-band) and 1570-1600 nm (long-wavelength band, L-band) using a saturating tone technique that represents 64 channels of a wavelength division multiplexed system. A bidirectional amplifying stage is utilized as high-power C-band and low-noise L-band stages. Noise figures of less than 3.6 and 5.4 dB are measured for the C- and L-bands, respectively.

Enhancing the radiation dose detection sensitivity of optical fibres

A glass-based substrate technology that fills the gap between a truly flexible extended length distributed sensor medium and the multifunctionality of optical chips is demonstrated. Flat fiber chips will open further degrees of freedom to control the behavior of light via mechanical manipulation. A flexible flat format will also allow straightforward incorporation into smart structures. Coupled with low manufacturing costs, these flexichips can also be a key enabler to disposable high-end sensing devices or fully distributed point sensors. In this study, Bragg gratings were used to demonstrate the optical flatness of the flat fiber core layer. Furthermore, the effective index values obtained from the grating experiment were input into a dynamic model, subsequently proving the influence of the dumbbell-shaped flat fiber cross section on the resultant UV written waveguides. Evanescent field sensing was also demonstrated by adopting a stepped Bragg approach.

High-gain bidirectional Er/sup 3+/-doped fiber amplifier for conventional- and long-wavelength bands

With interest in the potential of optical fibres as the basis of next-generation thermoluminescence dosimeters (TLDs), the development of suitable forms of material and their fabrication has become a fast-growing endeavour. Present study focuses on three types of Ge-doped optical fibres with different structural arrangements and/or shapes, namely conventional cylindrical fibre, capillary fibre, and flat fibre, all fabricated using the same optical fibre preform. For doses from 0.5 to 8 Gy, obtained at electron and photon energies, standard thermoluminescence (TL) characteristics of the optical fibres have been the subject of detailed investigation. The results show that in collapsing the capillary fibre into a flat shape, the TL yield is increased by a factor of 5.5, the yield being also some 3.2 times greater than that of the conventional cylindrical fibre fabricated from the same perform. This suggests a means of production of suitably sensitive TLD for in-vivo dosimeter applications. Addressing the associated defects generating luminescence from each of the optical fibres, the study encompasses analysis of the TL glow curves, with computerized glow curve deconvolution (CGCD) and 2nd order kinetics.

Direct UV Written Optical Waveguides in Flexible Glass Flat Fiber Chips

The design and optimization of straight long-range surface plasmon waveguides to maximize attenuation surface sensitivity in biochemical sensing applications are discussed. The sensor consists of a Au stripe embedded in CYTOP, with a microfluidic channel etched into the top cladding to expose the surface of the Au stripe and define the sensing channel. The attenuation α_s of the structure changes as a biological adlayer grows on the Au surface. The dimensions of the stripe (thickness, width), the sensing length and the refractive index of the sensing buffer were varied in order to understand their impact on sensor performance. The attenuation sensitivity ∂α_s/∂a dominates over a wide range of waveguide designs, so we define a parameter K = (∂α_s/∂a)/αs where maximizing |K| and selecting the optimal sensing length as L_opt = 1/(2α_s) maximizes the overall sensitivity of the structure. Experimental results based on observing the physisorption of bovine serum albumin (BSA) on bare Au waveguides agree qualitatively and quantitatively with theory. Detection limits of ΔΓ_min <; 0.1 pg·mm^-2 are predicted for optimal designs, and a detection limit of ΔΓ_min = 4.1pg/mm² (SNR = 1) is demonstrated experimentally for a sub-optimal structure.

Sensitive Fibre-Based Thermoluminescence Detectors for High Resolution In-Vivo Dosimetry.

This study presents the first investigation into the capability of fiber Bragg grating (FBG) sensors to measure interface pressure between the stump and the prosthetic sockets of a trans-tibial amputee. FBG element(s) were recoated with and embedded in a thin layer of epoxy material to form a sensing pad, which was in turn embedded in a silicone polymer material to form a pressure sensor. The sensor was tested in real time by inserting a heavy-duty balloon into the socket and inflating it by using an air compressor. This test was conducted to examine the sensitivity and repeatability of the sensor when subjected to pressure from the stump of the trans-tibial amputee and to mimic the actual environment of the amputees Patellar Tendon (PT) bar. The sensor exhibited a sensitivity of 127 pm/N and a maximum FSO hysteresis of around ∼0.09 in real-time operation. Very good reliability was achieved when the sensor was utilized for in situ measurements. This study may lead to smart FBG-based amputee stump/socket structures for pressure monitoring in amputee socket systems, which will result in better-designed prosthetic sockets that ensure improved patient satisfaction.