scholarly journals Extremely Low Effective Impedance in Stratified Graphene-Dielectric Metamaterials

2021 ◽  
Author(s):  
Ruey-Bing Hwang
Keyword(s):  
Refractive Index ◽  
Effective Refractive Index ◽  
Propagation Characteristic ◽  
Photonic Bandgaps ◽  
Impedance Mismatch ◽  
Numerical Examples ◽  
Graphene Layers ◽  
Effective Impedance ◽  
Effective Medium Approach ◽  
Multiple Interference

Abstract The periodic reflections in frequency were observed in a stack of graphene layers and reported as a series of mini photonic bandgaps owing to the multiple interference by the graphene layers. In this research, the effective medium approach was employed to obtain the effective refractive index and Bloch impedance for understanding the wave propagation characteristic therein. Specifically, the pure real effective refractive index without attenuation as well as an extremely low Bloch impedance were found at the frequencies exhibiting periodic reflections. Some numerical examples were demonstrated to show that the series bandgap-like reflections in fact are attributed to considerable impedance mismatch caused by this ultra low Bloch impedance.

An Ultra-Sensitive Optical Ring-Based Micro-Resonator Model towards Nanoparticle and Protein Detection

2018 ◽  
Vol 55 ◽  
pp. 57-65
Author(s):  
Faruk Ahmeti ◽  
Kasif Teker
Keyword(s):  
Refractive Index ◽  
Linear Correlation ◽  
Diagnostic Tool ◽  
Effective Refractive Index ◽  
Protein Detection ◽  
Microring Resonator ◽  
Protein Molecules ◽  
Effective Medium Approach ◽  
Resonator Model ◽  
Optical Ring

Optical resonator biosensors have emerged as one of the most sensitive and practical microsystem biodetection technology. Here, we have developed a model for an optical microring resonator to be used as an ultrasensitive biosensor. A linear correlation between increasing the radius of the microring and the red shift in the resonance wavelengths has been observed. In fact, resonance shifts for very small changes in microring radius, as low as 10 nm, have been detected. Furthermore, sensing capability of the resonator has been simulated by introducing TiDO2 nanoparticles and protein molecules to the resonator surface by varying both thickness and effective refractive index of the attached layer such that the layer size has been changed from 10 nm to 100 nm with an increment of 10 nm. We have observed readily detectable unique resonance shifts for both TiDO2 nanoparticles and protein molecules. Moreover, effective medium approach has been implemented in order to account for refractive index fluctuations in sensing medium. As a consequence, combination of optical resonators with microfluidics could produce a simple-to-operate, portable and robust diagnostic tool enabling new insights into biomolecular function and recognition.

scholarly journals NONLINEAR OPTICAL WAVEGUIDE STRUCTURE FOR SENSOR APPLICATION: TM CASE

2007 ◽  
Vol 21 (30) ◽  
pp. 5075-5089 ◽  
Author(s):  
HALA M. KHALIL ◽  
MOHAMMED M. SHABAT ◽  
SOFYAN A. TAYA ◽  
MAZEN M. ABADLA
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Closed Form ◽  
Optical Waveguide ◽  
Effective Refractive Index ◽  
Nonlinear Optical ◽  
Waveguide Structure ◽  
Analytical Expressions ◽  
Evanescent Waveguide ◽  
Waveguide Sensor

In this work, we present an extensive theoretical analysis of nonlinear optical waveguide sensor. The waveguide under consideration consists of a thin dielectrica film surrounded by a self-focused nonlinear cladding and a linear substrate. The nonlinearity of the cladding is considered to be of Kerr-type. Both cases, when the effective refractive index is greater and when it is smaller than the index of the guiding layer, are discussed. The sensitivity of the effective refractive index to any change in the cladding index in evanescent optical waveguide sensor is derived for TM modes. Closed form analytical expressions and normalized charts are given to provide the conditions required for the sensor to exhibit its maximum sensitivity. The results are compared with those of the well-known linear evanescent waveguide sensors.

scholarly journals Titania Photonic Crystals with Precise Photonic Band Gap Position via Anodizing with Voltage versus Optical Path Length Modulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 651 ◽  
Author(s):  
Ermolaev ◽  
Kushnir ◽  
Sapoletova ◽  
Napolskii
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Band Gap ◽  
Titanium Oxide ◽  
Effective Refractive Index ◽  
Photonic Band Gap ◽  
Voltage Versus ◽  
Research Attention ◽  
Anodic Titanium Oxide ◽  
Photonic Band

Photonic crystals based on titanium oxide are promising for optoelectronic applications, for example as components of solar cells and photodetectors. These materials attract great research attention because of the high refractive index of TiO2. One of the promising routes to prepare photonic crystals based on titanium oxide is titanium anodizing at periodically changing voltage or current. However, precise control of the photonic band gap position in anodic titania films is a challenge. To solve this problem, systematic data on the effective refractive index of the porous anodic titanium oxide are required. In this research, we determine quantitatively the dependence of the effective refractive index of porous anodic titanium oxide on the anodizing regime and develop a model which allows one to predict and, therefore, control photonic band gap position in the visible spectrum range with an accuracy better than 98.5%. The prospects of anodic titania photonic crystals implementation as refractive index sensors are demonstrated.

scholarly journals Refractive index evaluation of porous silicon using Bragg reflectors

2018 ◽  
Vol 64 (1) ◽  
pp. 72 ◽  
Author(s):  
D. Estrada-Wiese ◽  
J.A. Del Río
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Simple Procedure ◽  
Merit Function ◽  
Refractive Indices ◽  
Bragg Reflectors ◽  
Photonic Bandgaps ◽  
Photonic Structures ◽  
Index Evaluation

There are two main physical properties needed to fabricate 1D photonic structures and form perfect photonic bandgaps: the quality of thethickness periodicity and the refractive index of their components. Porous silicon (PS) is a nano-structured material widely used to prepare 1Dphotonic crystals due to the ease of tuning its porosity and its refractive index by changing the fabrication conditions. Since the morphologyof PS changes with porosity, the determination of PS’s refractive index is no easy task. To find the optical properties of PS we can usedifferent effective medium approximations (EMA). In this work we propose a method to evaluate the performance of the refractive index ofPS layers to build photonic Bragg reflectors. Through a quality factor we measure the agreement between theory and experiment and thereinpropose a simple procedure to determine the usability of the refractive indices. We test the obtained refractive indices in more complicatedstructures, such as a broadband Vis-NIR mirror, and by means of a Merit function we find a good agreement between theory and experiment.With this study we have proposed quantitative parameters to evaluate the refractive index for PS Bragg reflectors. This procedure could havean impact on the design and fabrication of 1D photonic structures for different applications.

scholarly journals Modes Effective Refractive Index Difference Measurement in Few-mode Optical Fiber

2016 ◽  
Vol 140 ◽  
pp. 77-84 ◽  
Author(s):  
Jing Zhang ◽  
Zhifang Wu ◽  
Tianye Huang ◽  
Xuguang Shao ◽  
Ping Shum
Keyword(s):  
Refractive Index ◽  
Optical Fiber ◽  
Effective Refractive Index ◽  
Difference Measurement ◽  
Refractive Index Difference
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