Soft surfaces and enhanced nonlinearity enabled via epsilon-near-zero media doped with zero-area perfect electric conductor inclusions

Introducing a dielectric inclusion inside an epsilon-near-zero (ENZ) host has been shown to dramatically affect the effective permeability of the host for a TM-polarized incident wave, a concept coined as photonic doping [Science 355, 1058 (2017)]. Here, we theoretically study the prospect of doping the ENZ host with infinitesimally thin perfect electric conductor (PEC) inclusions, which we call 'zero-area' PEC dopants. First, we theoretically demonstrate that zero-area PEC dopants enable the design of soft surfaces with an arbitrary cross-sectional geometry. Second, we illustrate the possibility of engineering the PEC dopants with the goal of transforming the electric field distribution inside the ENZ while maintaining a spatially invariant magnetic field. We exploit this property to enhance the effective nonlinearity of the ENZ host.Ministerio de Ciencia, Innovación y Universidades (MCIU/AEI/FEDER/UE, RTI2018-093714-JI00); Air Force Office of Scientific Research (FA9550-14-1-0389); Office of Naval Research (N00014-16-1-2029)

Enhanced Nonlinearity Enabled Via Doped Enz Metastructures: Theory & Potential Applications

Synthetic composite structures, known as metamaterials, have been increasingly applied in the past two decades in numerous applications for obtaining electromagnetic characteristics far beyond those available in naturally occurring materials. In particular, epsilon-near-zero (ENZ) media are a special category of metamaterials which have been shown to exhibit exotic wave-matter interaction properties, rendering them suitable for various applications. It has been recently theoretically and experimentally demonstrated that a 2D ENZ body (i.e. infinitely extended along a given direction) doped with a dielectric inclusion is equivalent to a magnetic ENZ medium for an outside observer, a concept coined “photonic doping”. In this dissertation, I theoretically extend this concept for additional classes of inclusions and propose several potential applications harnessing the peculiar electromagnetic characteristics of such structures. First, I theoretically demonstrate that a nonmagnetic linear ENZ host doped with a single Kerr dielectric inclusion is effectively perceived as an ENZ medium with enhanced magnetic nonlinearity. As an application of this concept, an ENZ slab doped with a Kerr dielectric rod is deployed for designing nonlinear absorbers where the absorption bandwidth may be tailored, in addition to dynamically shifting the absorption spectrum. Subsequently, doping ENZ media by infinitesimally thin PEC inclusions is studied. Such “zero-area” PEC inclusions are theoretically shown to be capable of shaping the electric field distribution inside the ENZ medium while maintaining the magnetic field distribution intact, enhancing the nonlinearity of a Kerr nonlinear ENZ host, and designing soft surfaces with arbitrary geometry, which behave as a perfect magnetic conductor and perfect electric conductor for the TM and TE polarizations, respectively. Furthermore, compact and tunable resonators formed by an air gap separating two doped ENZ slabs are shown to provide a mechanism for highly tunable radiation enhancement or suppression. Finally, the transient response of ENZ media doped by dielectrics with time-varying permittivity is numerically studied to understand the time scale required for reaching steady-state field distributions and the various factors which affect the transient response time, such as the loss, size, geometry of the ENZ host, and the dielectric inclusion properties

Enhanced Nonlinearity Enabled via Doped ENZ Metastructures: Theory & Potential Applications

Synthetic composite structures, known as metamaterials, have been increasingly applied in the past two decades in numerous applications for obtaining electromagnetic characteristics far beyond those available in naturally occurring materials. In particular, epsilon-near-zero (ENZ) media are a special category of metamaterials which have been shown to exhibit exotic wave-matter interaction properties, rendering them suitable for various applications. It has been recently theoretically and experimentally demonstrated that a 2D ENZ body (i.e. infinitely extended along a given direction) doped with a dielectric inclusion is equivalent to a magnetic ENZ medium for an outside observer, a concept coined “photonic doping”. In this dissertation, I theoretically extend this concept for additional classes of inclusions and propose several potential applications harnessing the peculiar electromagnetic characteristics of such structures. First, I theoretically demonstrate that a nonmagnetic linear ENZ host doped with a single Kerr dielectric inclusion is effectively perceived as an ENZ medium with enhanced magnetic nonlinearity. As an application of this concept, an ENZ slab doped with a Kerr dielectric rod is deployed for designing nonlinear absorbers where the absorption bandwidth may be tailored, in addition to dynamically shifting the absorption spectrum. Subsequently, doping ENZ media by infinitesimally thin PEC inclusions is studied. Such “zero-area” PEC inclusions are theoretically shown to be capable of shaping the electric field distribution inside the ENZ medium while maintaining the magnetic field distribution intact, enhancing the nonlinearity of a Kerr nonlinear ENZ host, and designing soft surfaces with arbitrary geometry, which behave as a perfect magnetic conductor and perfect electric conductor for the TM and TE polarizations, respectively. Furthermore, compact and tunable resonators formed by an air gap separating two doped ENZ slabs are shown to provide a mechanism for highly tunable radiation enhancement or suppression. Finally, the transient response of ENZ media doped by dielectrics with time-varying permittivity is numerically studied to understand the time scale required for reaching steady-state field distributions and the various factors which affect the transient response time, such as the loss, size, geometry of the ENZ host, and the dielectric inclusion properties

Prevalence of Periodontal Disease in Type 2 Diabetic Patients with and without Vitamin D Deficiency

Introduction: Diabetes mellitus is one of the most common endocrine disorders in the world and is accompanied with many complications such as periodontal disorders as the most common complications of diabetes in the mouth. It is estimated that 1 million people worldwide are suffering from varying degrees of vitamin D deficiency, and some studies have linked it with periodontitis and diabetes. The purpose of this study is to investigate the relationship between periodontal disease in type 2 Diabetic patients and vitamin D deficiency in Iranian population. Materials and Methods: This cross-sectional study conducted on 74 Iranian patients admitted to Baqiyatallah hospital during the years 2017-2019. The type II diabetic patients were selected and non-volunteers patients and those who did not meet the inclusion criteria were excluded. Then, Necessary tests were evaluated in all patients. Patients were divided into two groups of with and without vitamin D deficiency. A questionnaire for periodontal disorders was completed by two different blinded periodontists. The collected data was analyzed using SPSS-21 software using Chi-square and T-test. Results: 44 males and 30 females were studied. 37 patients had vitamin D levels below 30 ng/ml. 83.8% of the patients had periodontal disorders. The frequency of periodontitis was higher in diabetic patients with vitamin D deficiency than in diabetic patients with normal levels of vitamin D. Periodontal disorders were also significantly correlated with duration of diabetes, age of patients and HbA1c. Conclusion: Periodontal disorder is more prevalent in patients with inadequate vitamin D serum levels. Screening for diabetic patients seems to be necessary both in terms of diagnosis of periodontitis and vitamin D deficiency