Design and Analysis of Pseudospin-Polarized Ultra-Wideband Waveguide Supporting Hybrid Spoof Surface Plasmon Polaritons

In this study, novel low-loss waveguides and power dividers for ultra-broadband surface plasmon polaritons (SPPs) are introduced. This article uses complementary metasurfaces in place of traditional SPP, which are typically produced as metasurface unit cells on the dielectric sublayer. It has been demonstrated that the use of complementary metasurfaces considerably improves wave confinement and inhibits wave propagation. Because of this, it is anticipated that waveguides and power dividers made from these complimentary unit cells will have significantly lower losses and greater bandwidth than SPP used in traditional devices. In the frequency range of 0 GHz to 100 GHz, waveguides and bent waveguides with complementary metasurface unit cells exhibit insertion loss greater than 0.5 dB. Utilizing complementary metasurfaces, symmetric and asymmetric power dividers have been created and researched. The results of the simulation have shown that using this type of unit cell in the construction of microwave devices is advantageous.Comment: 13 pages 12 figure

Ultra-fast all-optical 8-to-3 encoder utilizing photonic crystal fiber

This work proposes a novel design of an 8-to-3 encoder in a photonic crystal fiber (PCF). It is composed of a buffer and three OR logic gates using circular air holes in a silicon dioxide substrate. We have employed the plane-wave expansion technique to analyze the band structure of the proposed PCF and the beam propagation method to study the transmission efficiency and electromagnetic field distributions. Our findings reveal that the encoder operates well within the main third telecommunication window, which corresponds to 1530–1565 nm. The numerical calculations show that transmissions greater than 70% and less than 0.05% are logics 1 and 0, respectively. The proposed encoder has a maximum delay of 7.5 ps, and its total footprint is about 140 µm × 14 µm × 3 mm. This makes the proposed PCF-based encoder suitable for simple and low-cost fabrication, which may find applications in optical communication devices and integrated circuits

Gender Stereotypes at Work

Originally published in Applied Optics on 10 March 2015 (ao-54-8-2072

Effect of Emission Penalty and Annual Interest Rate on Cogeneration of Electricity, Heat, and Hydrogen in Karachi: 3E Assessment and Sensitivity Analysis

Pakistan is the world’s sixth-most populous country with a semi-industrialized economy. It has been always an energy importer and dependent on fossil fuels. Great pressure is imposed on Pakistan’s national grid from the rise in fossil fuel costs, variations in the annual interest rate, and increased costs of greenhouse emissions. To meet the ever-increasing energy demand, the Government of Pakistan has decided to further harness wind and solar energies currently having a negligible share in Pakistan’s energy portfolio. Despite the importance of this issue, no study has been conducted so far on the cogeneration of power, heat, and hydrogen in Pakistan. Accordingly, this study is aimed at technical–economic–environmental sensitivity analysis of supplying electric and thermal loads of a residential building in Karachi by an off-grid wind-solar-fuel cell system. To this end, 4500000 possible cases were analyzed, simulated, and optimized with the HOMER software using 20-year average meteorological data from the NASA website. A sensitivity analysis was performed on this system for the first time in Pakistan. The other novelties are the use of dump loads for converting the surplus electricity into heat and also heat recovering in the fuel cells. The results showed the great potential of the station understudy for supplying the required power and heat by renewable energies. Hydrogen production was also affordable at every emission penalty price with an interest rate of less than 9%. Moreover, dump loads play a key role in supplying the thermal demand. Comparison of the wind turbine–solar cell–fuel cell–battery system with the wind turbine–solar cell–battery and solar cell–battery systems indicated that the internal rate of return and the payback period were, respectively, 9.39% and 11.4 years and 11.7% and 11 years. According to these results, it is recommend that Pakistani authorities promote the use of renewable energies through incentives and investment subsidies

Line-wave waveguide engineering using Hermitian and non-Hermitian metasurfaces

Abstract Line waves (LWs) refer to confined edge modes that propagate along the interface of dual electromagnetic metasurfaces while maintaining mirror reflection symmetries. Previous research has both theoretically and experimentally investigated these waves, revealing their presence in the microwave and terahertz frequency ranges. In addition, a comprehensive exploration has been conducted on the implementation of non-Hermitian LWs by establishing the parity-time symmetry. This study introduces a cutting-edge dual-band line-wave waveguide, enabling the realization of LWs within the terahertz and infrared spectrums. Our work is centered around analyzing the functionalities of existing applications of LWs within a specific field. In addition, a novel non-Hermitian platform is proposed. We address feasible practical implementations of non-Hermitian LWs by placing a graphene-based metasurface on an epsilon-near-zero material. This study delves into the advantages of the proposed framework compared to previously examined structures, involving both analytical and numerical examinations of how these waves propagate and the underlying physical mechanisms