Ghulam Ishaq Khan Institute of Engineering Sciences and Technology

About: Ghulam Ishaq Khan Institute of Engineering Sciences and Technology is a education organization based out in Topi, Pakistan. It is known for research contribution in the topics: Quantum efficiency & Diode. The organization has 618 authors who have published 940 publications receiving 10674 citations.

Highly Efficient All-dielectric Metasurfaces for Airy Beam Generation in Visible Domain

Abstract: Metasurfaces, the planar analog of bulk metamaterials, can be patterned at the interface of two media to control the amplitude, polarization, and phase of the incident light. Metasurfaces have provided a unique platform for the on-chip realization of various interesting phenomena such as light-twisting, structuring, lensing, imaging, beam-splitting, etc. Since the performance of metasurfaces based on metallic scatterers is restricted by ohmic losses and associated optical absorption, lossless dielectric materials (in the spectrum of interest) provide a promising alternative to acquire higher transmission efficiency. In this article, we utilize hydrogenated amorphous silicon (a-Si: H) nano-scatterers (with a subwavelength thickness of 300 nm), which provides a cost-effective (compared to TiO 2 and GaN) and low-loss (compared to metallic counterparts) alternative, to design an efficient metasurface in the visible domain. The proposed metasurface can generate the finite energy Airy beam by simultaneously engineering the cross-polarized transmission amplitude and phase of the transmitted electromagnetic wave at the visible wavelength of 633 nm. The polarization and phase are engineered by varying the orientation of nano-bars while cross-polarized transmission amplitude is optimized by tuning the geometric parameters of nano-bars. Higher cross-polarized transmission amplitude (73%) is achieved compared to previously reported work. The proposed design will help us in developing subwavelength-thick flat devices that have numerous applications in integrated optics such as optical manipulation, bio-sensing, beam shaping, and forming optical bullets.

Enhancement of electrical properties of vanadyl phthalocyanine derivative by PCBM

Abstract: Purpose – The purpose of this paper is to investigate the effect of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) on improvement of physical and electrical properties of vanadyl phthalocyanine derivative. The correlation between the physical characteristics of the active layers, comprising vanadyl 2,9,16, 23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO) and PCBM, and the electrical properties of metal/organic/metal devices have been studied. The use of soluble vanadyl phthalocyanine derivative makes it very attractive for a variety of applications due to its tunable properties and high solubility. Design/methodology/approach – The sandwich type structures Al/VOPcPhO/Al and Al/VOPcPhO:PCBM/Al were fabricated by spin casting the active organic layers between the top and bottom (aluminum) electrodes. The stand-alone (VOPcPhO) and composite (VOPcPhO:PCBM) thin films were characterized by X-ray diffraction, atomic force microscopy, UV/Vis and Raman spectroscopy. The electronic properties of the metal/organ...

Electromagnetic fields in a circular waveguide with D'B'-boundary conditions internally coated with chiral-nihility medium

Abstract: The present study deals with the propagation of electromagnetic fields and power in a circular waveguide, with D'B'- boundary conditions, internally coated with chiral-nihility medium. The electromagnetic fields inside the two layer circular waveguide defined by D'B'-boundary conditions, with one layer containing free space while other layer containing chiral- nihility medium, is investigated. D'B'-boundary conditions require vanishing of derivatives of the normal field components of D and B vectors, hence named as D'B'-boundary conditions. It has been investigated that unlike to the chiral-nihility coated perfect electromagnetic conductor (PEC) waveguide, there is a non-zero power transfer in chiral-nihility region in waveguide with D'B' boundary conditions.