A photonic crystal fiber (PCF) for sensing of sulfuric acid is designed and analyzed using Comsol Multiphysics. To analyze the sensor performance, 0%, 10%, 20%, 30%, 40% H₂SO₄ solution is placed into the fiber separately and then relative sensitivity, confinement loss, birefringence, effective area etc. are investigated for each solution over wavelength ranging from 0.8 to 1.8 µm. The sensor structure affords moderately high relative sensitivity and around 63.4% sensitivity is achieved for the highest concentration of H₂SO₄ at the wavelength 1.5 µm in x polarization direction. This PCF model also shows zero confinement loss for all solutions of H₂SO₄ over wavelength ranging from 1 to 1.35 µm and later on approximately 1.422 × 10⁻¹⁷ dB/km confinement loss is found for the highest concentration of H₂SO₄ at 1.5 µm wavelength. Besides, higher birefringence is attained when the concentration of sulfuric acid is lower and it is achieved 7.5 × 10⁻⁴ at 1.5 µm wavelength. Moreover, higher sensing area is achieved at high concentration of sulfuric acid.

High birefringence with low confinement loss photonic crystal fiber (PCF) has significant advantages in the field of sensing, dispersion compensation devices, nonlinear applications, and polarization filter. In this report, two different models of PCFs are presented and compared. Both the models contain five air holes rings with combination of circular and elliptical air holes arrangement. Moreover, the elliptical shaped air holes polarization and the third ring air holes rotational angle are varied. To examine different guiding characteristics, finite element method (FEM) with perfectly matched layer (PML) absorbing boundary condition is applied from 1.2 to 1.8 μm wavelength range. High birefringence, low confinement loss, high nonlinearity, and moderate dispersion values are successfully achieved in both the PCFs models. Numeric analysis shows that model-1 gives higher birefringence (2.75 × 10^–2) and negative dispersion (–540.67 ps/(nm$km)) at 1.55 μm wavelength. However, model-2 gives more small confinement loss than model-1 at the same wavelength. In addition, the proposed design demonstrates the variation of rotation angle has great impact to enhance guiding properties especially the birefringence.

Solid core circular and octagonal photonic crystal fibers (CPCF and OPCF) are proposed for analyzing different guiding properties such as dispersion, effective mode area, nonlinearity, and confinement loss from 0.8 to 2.6 µm wavelength. The proposed structures use three different types of background materials: SF10, BK7, and silica. Moreover, the fill fraction is varied by changing the diameter of the air hole where the lattice pitch is unchanged. The proposed PCFs show a high negative dispersion with low confinement loss and small effective mode area. In the proposed design, the finite element method with a perfectly matched layer absorbing boundary condition is used. At 1.8 µm wavelength with 0.6 fill fraction, the maximum negative dispersion of − 922.5 p s / ( n m . k m ) is observed for CPCF when the background material is SF10. In addition, at this particular wavelength, the confinement loss is observed to be very small. Moreover, − 560.12 p s / ( n m . k m ) dispersion is found for the similar condition at 1.55 µm wavelength. On the other hand, using BK7 as the background material, − 706.77 p s / ( n m . k m ) dispersion is found at 1.55 µm wavelength for CPCF. Results also imply that CPCF shows better performance than OPCF for a wide wavelength range. Furthermore, at 1.55 µm wavelength, silica-based glass exhibits maximum dispersion, whereas increasing wavelength flint type glass shows the similar result. Analyzing different guiding properties of PCFs has significant impact on broadband dispersion compensation applications, especially using SF10.

Cloud computing has become a part and parcel of our daily life. It just made our life easier with its amazing features. To support increasing number of users as well as smart devices, it is needed to keep the cloud environment more and more secure and reliable. Cloud computing security has become a major challenging field now a days. In this paper we presented a Fuzzy based mechanism, which may be helpful for the detection of Distributed Denial of Service (DDoS) attack in cloud computing environment. As DDoS attack becomes powerful with the passing of time, if it is detected at first, then the attack may be minimized. So we focused on attack detection mechanism to secure the cloud environment using Fuzzy logic.

Graphene has impressive features that make it an exceptional material for sophisticated applications in next generation electronics and opto-electronics devices. This peremptory material has attracted researchers’ attention in various fields of recent advancement since its discovery in 2004. Its applied fields are increasing day by day. This two-dimensional material (2D) is using mellifluously for the development in different types of devices in the field of optics, photonics, light emitting diode (LED), medical diagnosis, sensing, and so on. In this review, the relevant optical properties and the applications areas with available results in various fields are discussed. Again, the optical conductivity of strained graphene is reviewed in a wavelength related regime that depends on strain modulus and position with field arrangements. Graphene shows a saturation and reverse saturation process due to the increase of light intensity. In addition, strong absorption is observed from the visible to mid-infrared (MIR) wavelength range. Moreover, the application areas of graphene including optics, photonics, plasmonics, mode-locked laser, optical modulator, etc., and the comparison of various results obtained from different sources are presented.