1. Type 1 diabetes (due to b-cell destruction, usually leading to absolute insulin deficiency) 2. Type 2 diabetes (due to a progressive insulin secretory defect on the background of insulin resistance) 3. Gestational diabetes mellitus (GDM) (diabetes diagnosed in the second or third trimester of pregnancy that is not clearly overt diabetes) 4. Specific types of diabetes due to other causes, e.g., monogenic diabetes syndromes (such as neonatal diabetes and maturity-onset diabetes of the young [MODY]), diseases of the exocrine pancreas (such as cystic fibrosis), and drugor chemical-induced diabetes (such as in the treatment of HIV/AIDS or after organ transplantation)

Classification and diagnosis of diabetes

We investigate the design, fabrication, and experimental characterization of high quality factor photonic crystal nanobeam cavities in silicon. Using a five-hole tapered one-dimensional photonic crystal mirror and precise control of the cavity length, we designed cavities with theoretical quality factors as high as 1.4×107. By detecting the cross-polarized resonantly scattered light from a normally incident laser beam, we measure a quality factor of nearly 7.5×105. The effect of cavity size on mode frequency and quality factor was simulated and then verified experimentally.

High quality factor photonic crystal nanobeam cavities

We demonstrate room-temperature pulsed laser emission from optically pumped metallo-dielectric cavities that are smaller than their emission wavelength in all three dimensions. The cavity consists of an aluminium/silica bi-layer shield surrounding an InGaAsP disk in which the thickness of the silica layer is optimized to minimize the gain threshold of the laser. The lasers are pumped using a 1,064-nm pulsed fibre laser with a pulse width of 12 ns and repetition rate of 300 kHz. Lasing emission at 1.43 µm is observed from a laser with slightly elliptical gain core with major and minor diameters of 490 and 420 nm, respectively. Owing to the isolation provided by the aluminium shield, this laser design approach can be used to create arrays of uncoupled lasers with emitter densities that are close to the Rayleigh resolution limit. Room-temperature lasing from metallo-dielectric cavities that are smaller than their emission wavelength in all three dimensions is reported. The cavity consists of an aluminium/silica bi-layer shield that surrounds an InGaAsP disk. The gain threshold of the laser is minimized by optimizing the thickness of the silica layer.

Room-temperature subwavelength metallo-dielectric lasers

Coupled optical resonators are one approach to slowing the propagation of light. An array of more than 100 such resonators has now been demonstrated using a photonic crystal. Such a structure can slow light down to below 1% of its speed in a vacuum.

Large-scale arrays of ultrahigh-Q coupled nanocavities

Photonic crystal nanobeam cavities are versatile platforms of interest for optical communications, optomechanics, optofluidics, cavity QED, etc. In a previous work [Appl. Phys. Lett. 96, 203102 (2010)], we proposed a deterministic method to achieve ultrahigh Q cavities. This follow-up work provides systematic analysis and verifications of the deterministic design recipe and further extends the discussion to air-mode cavities. We demonstrate designs of dielectric-mode and air-mode cavities with Q > 10⁹, as well as dielectric-mode nanobeam cavities with both ultrahigh-Q (> 10⁷) and ultrahigh on-resonance transmissions (T > 95%).

Deterministic design of wavelength scale, ultra-high Q photonic crystal nanobeam cavities

Designing a high sensitivity device has been a research focus and a requirement in biosensor application. We found out that one of the way to increase the sensitivity of an optical biosensor device is to increase the interaction area between the target analyte and the sensing region of the biosensor device where the light propagates. Using a high quality-factor (Q) one dimensional photonic crystal (1D PhC) biosensor structure based on silicon-on-insulator (SOI) material, we showed here the increase in the device's sensitivity as we gradually increase the analyte interaction area with the device's sensing region, side by side until all area around the sensing region are utilized in the sensing. 3D FDTD simulation tool was used. Final sensitivity is increased by up to 500% — as compared to only utilizing the top part of the 1D PhC. Mode profile analysis of the waveguide shows and suggests that the evanescent field of the guided light and the slotted periodic holes can be exploited for sensing in all direction surrounding the PhC. Analysis of this technique is supported by the optical path length (OPL) of the Fermat's principle theory. This research's output is important in designing a high sensitivity PhC biosensor and also other related optical biosensor device.

Sensitivity increment of one dimensional photonic crystal biosensor

In this work, we report a graphene-alkaline lignin-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate composite as a transparent conductive electrode for indium tin oxide-free optoelectronic de...

https://journals.sagepub.com/doi/pdf/10.1177/18479804211015009

Exfoliated graphene-alkaline lignin-PEDOT: PSS composite as a transparent conductive electrode:

We have theoretically demonstrated the variation of geometrical parameters for the cavities design of one dimensional (1D) photonic crystal nanocavity based on silicon on insulator (SOI) waveguides. To evaluate the cavity numerically, we have successfully computed it using the 2D finite difference time domain (FDTD) approach. We have varied the geometrical hole size, lattice and number of cavity. We have also varied the length of the cavity parameter, from 530 to 675 nm and for lattice constant from 345 to 410 nm. The optimized quality factors of approximately 4300 at 1617.9 nm resonance wavelengths were obtained and the free spectral range (FSR) was calculated to be in the range of 10 to 60 nm.

Numerical simulation of one dimensional (1D) photonic crystal multiple cavities based on silicon on insulator (SOI)

In recent years, many researchers have shown their interest in producing a compact high-performance optical chip that is useful for most telecommunication applications. One of the solutions is by realising photonic crystal (PhC) structures that exhibit high-quality factors in a small mode volume, V. Silicon on insulator (SOI) is one of the main contenders due to its high-index contrast between the silicon (Si) core waveguide with silica (SiO2) cladding surrounding it. The maturity of silicon photonic can also be incorporated with CMOS chips making it a desired material. A strong optical confinement provided by PhC structures makes it possible to realise the compact device on a single chip. In this chapter, we will discuss a fundamental background of photonic crystal cavities mainly on one-dimensional (1D) structures, which are the simplest as compared to their counterparts, 2D and 3D PhC device structures. We have modelled a photonic crystal cavity using finitedifference time-domain (FDTD) approach. This approach uses time-dependent Maxwell equation to cover wide frequency range in a single simulation. The results are then compared with the actual measured results showing a significant agreement between them. The design will be used as basic building block for designing a more complex PhC structures that exhibit high-quality factors for applications such as filtering, DWDM and sensors.

/pdf/modelling-of-photonic-crystal-phc-cavities-theory-and-4zacbqxge0.pdf

Modelling of Photonic Crystal (PhC) Cavities: Theory and Applications

Metamaterials have been of great interest owing to multifarious technological applications. Among various applications of scientific need, the perfect absorber kind of property of metamaterials remains prudent. Within the context, this investigation describes the filtering/absorber applications of metasurfaces comprised of columnar nanorods of gold having circular and elliptical cross-sections. The spectral features of such absorbers are investigated in terms of absorptivity in the visible to infrared (IR) regimes. The results indicate of almost perfect absorption corresponding to certain wavelengths in the IR span. Also, multiple absorption peaks would determine the filtering characteristics of the structures under consideration. It has been found that the absorber having circular nanorods exhibits better performance than the one with elliptical nanorods in terms of the magnitude/smoothness of absorption peaks in the entire electromagnetic spectral region of interest; the case of elliptical nanorods makes the absorption spectra to yield too much of flickers in the IR range of wavelength.

Ahmad Rifqi Md Zain

Papers

Sensitivity increment of one dimensional photonic crystal biosensor

Exfoliated graphene-alkaline lignin-PEDOT: PSS composite as a transparent conductive electrode:

Numerical simulation of one dimensional (1D) photonic crystal multiple cavities based on silicon on insulator (SOI)

Modelling of Photonic Crystal (PhC) Cavities: Theory and Applications

On the frequency-selective features of gold nanorods-based columnar thin film metamaterial absorber