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A new adaptive finite element (FE) technique is proposed to enhance the accuracy of the solution of wave propagation in integrated photonic devices. The suggested recovery technique improves significantly the finite element convergence rate compared to refinement techniques. The method refines the elements based on the field distribution. This recovery technique estimates the error at each element by comparing the linear FE solution and the recovery solution using least-squares method. The numerical aspects and accuracy of the method are investigated using the light propagation in both one-dimensional and two-dimensional photonic devices. [ABSTRACT FROM AUTHOR]

In this paper, a novel design of superlens based on photonic bandgap structure for high resolution point spread function (PSF) is reported at a wavelength of 3 μm. The lens is able to generate a non-diffraction Bessel beam with a number of focusing points with variant resolution limits. The optimized structure provides high resolution in both lateral and axial directions. The maximum achieved lateral resolution of PSF is down to ~ 0.27λ with corresponding axial resolution down to ~ 0.57λ attaining a FOM, the inverse of the product of both resolution limits, of ~ 6.49. Meanwhile, the maximum axial resolution is down to ~ 0.4λ with corresponding lateral resolution down to ~ 0.33λ with a FOM of ~ 7.34. In addition, the proposed design is able to generate a focusing point extended in space up to ~ 0.98 µm with a sub-diffraction lateral resolution down to ~ 0.47λ. Furthermore, the reported superlens demonstrates a sub-diffraction focusing in lateral direction along the range the bandgap wavelengths (from 2.4 to 3.6 µm) showing a significant increase of focal depth when decreasing the operating wavelength. Remarkably, a high focal depth up to ~ 1.77 µm is achieved at the operating wavelength of 2.6 µm. The suggested design has a tremendous potential in 3D biological imaging and biosensing applications. [ABSTRACT FROM AUTHOR]

A highly sensitive 2D Si photonic crystal (PhC) sensor is proposed and analyzed for the detection of gamma-ray doses in the visible light region. The suggested PhC has a cavity infiltrated by poly-vinyl alcohol (PVA) polymer doped with crystal violet and carbol fuchsine dyes. The transmission through the proposed design has a peak at the resonance frequency, which is sensitive to the gamma-ray doses. The geometrical parameters of the suggested PhC are studied to maximize the sensor sensitivity, quality factor, and normalized transmission. The proposed sensor achieves high sensitivity of 150 nm per refractive index unit (nm/RIU) with high linearity and high-quality factor (Q) of 808. The analysis is carried out using full-vectorial finite-element method and the plane wave expansion method. To the best of the author's knowledge, it is the first time to use 2D-PhC technology for gamma-ray detection. [ABSTRACT FROM AUTHOR]

Reconfigurable unidirectional transmission based on the nematic liquid crystal (NLC) layer and 2-D photonic crystal (PhC) platforms is presented and simulated. The suggested one way transmission can be tuned at different wavelengths based on the NLC biasing state. A comprehensive parametric study using plane wave expansion and finite difference time domain (FDTD) methods has been carried out for explaining and optimizing the performance of the proposed structure. The transmission spectra calculations reveal that the reported structure can perform nearly perfect isolation at two different bands (1406–1412 nm and 1416–1421 nm) with an average contrast ratio (Cr) of about 36.9 dB. The investigated unidirectional PhC structure has advantages in terms of compactness and reconfigurability and can be used efficiently in ultrahigh nanoscale integrated circuits. [ABSTRACT FROM PUBLISHER]

In this paper, one-dimensional photonic crystal with periodic multilayers of dielectrics and central nematic liquid crystal (NLC) defect is presented and analyzed. The transmission and field distribution of the transverse magnetic (TM) mode through the suggested design are studied using finite element time domain method. The effect of the structure geometrical parameters on the transmission of the TM mode is investigated and analyzed. Further, the impacts of the rotation angle of the director of NLC and temperature are also studied. The numerical results show that the reported design can be used as an optical filter around a wavelength of 1300 nm which is very important for communication applications. Additionally, the suggested design has high tunability due to the infiltration of the NLC material. [ABSTRACT FROM AUTHOR]

In this study, a novel compact and fully integrated 2D photonic crystal (PhC) biosensor with high sensitivity has been proposed for Glucose monitoring. The simulation results are obtained using 2D finite element time domain method (FETDM). To evaluate the performance of the suggested design, the transmission spectrum through the reported structure has been calculated. The effect of the structure geometrical parameters of the biosensor is studied to maximize the biosensor sensitivity. The suggested biosensor offers high sensitivity of 422 nm/RIU with high linearity. Additionally, the suggested biosensor has a simple design and is easy for fabrication. The enhancement of the sensitivity of the PhC biosensor is very important to amplify the detection of the small variation in analyte's physical properties. Therefore, the achieved sensitivity enhancement can improve the applications of Glucose monitoring. [ABSTRACT FROM AUTHOR]

In this study, a novel design of porous octagonal photonic crystal fibre with a metal‐coated central hole is investigated and analysed in the terahertz (THz) range. The suggested structure is analysed near a frequency of 1.0 THz by using the full vectorial finite difference method. The effects of the structure geometrical parameters and bending radius on the mode effective index, effective mode area and attenuation of the proposed design are investigated. The numerical results reveal that the effective mode area with a metal‐coated central hole is smaller than that of porous core without a metal‐coated central hole by 80%. In addition, very low attenuation can be obtained because of the porosity inside the core region. [ABSTRACT FROM AUTHOR]

A rigorous analysis of polarisation conversion in a novel design of cascaded bent silica photonic crystal fibre is proposed using full vectorial finite difference method as well as full vectorial finite difference beam propagation method. The influence of different structural geometrical parameters on the polarisation rotator performance is investigated. The numerical results reveal that by a careful adjustment of the structural geometrical parameters and bending radius, nearly a 100% polarisation conversion ratio with nine sections only and low bending losses can be achieved. [ABSTRACT FROM AUTHOR]

Ultracompact simultaneous XOR and XNOR logic gates are proposed and analyzed. The suggested design is based on two-dimensional Si photonic crystal (PhC) with a central hole infiltrated by nematic liquid crystal (NLC) of type E7. The plane wave expansion method is used to obtain the photonic bandgap for both transverse electric mode and transverse magnetic mode. Further, the transmission through the proposed logic gates is calculated by the full vectorial finite element method. The numerical results show that the reported XOR and XNOR logic gates can be operated around wavelength of 1500 nm. In addition, the operation of the designed logic gates can be switched on/off by controlling the NLC biasing state. Such PhC logic gates have a compact size of 47 μm2 and can achieve a large contrast ratio of 26 dB. Therefore, the suggested design has advantages in terms of tunability, low power consumption, compact size, simplicity, and compatibility with nowadays fabrication technology, which will be suitable for photonic integrated circuits. [ABSTRACT FROM AUTHOR]

A Hemoglobin (Hb) biosensor based on dual-core photonic crystal fiber is proposed and analyzed. In this paper, the effective refractive index dependency on the Hb concentration within a blood sample is utilized in obtaining the transmission spectrum variation. The results are calculated using full vectorial finite element method. Through this study, the effect of the structure geometrical parameters on the sensor performance is optimized to maximize the sensor sensitivity. The numerical results show a sensitivity of 8.013 nm/g/dL for the X-polarized mode at 3.7 cm fiber length and 7.68 nm/g/dL for the Y-polarized mode at 3.2 cm fiber length of the proposed sensor. [ABSTRACT FROM AUTHOR]