scholarly journals Reflection Enhancement and Giant Lateral Shift in Defective Photonic Crystals with Graphene

2019 ◽  
Vol 9 (10) ◽  
pp. 2141 ◽  
Author(s):  
Dong Zhao ◽  
Fangmei Liu ◽  
Peng Meng ◽  
Jie Wen ◽  
Siliu Xu ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Interband Transition ◽  
Single Layer ◽  
Defect Layer ◽  
Lateral Shift ◽  
Single Layer Graphene ◽  
Intraband Transition ◽  
Highly Sensitive ◽  
Highly Sensitive Sensors ◽  
Periodic Number

This study investigates the reflectance of the defective mode (DM) and the lateral shift of reflected beam in defective photonic crystals incorporated with single-layer graphene by the transfer matrix method (TMM). Graphene, treated as an equivalent dielectric with a thickness of 0.34 nm, was embedded in the center of a defect layer. The reflectance of the DM was greatly enhanced as the intraband transition of electrons was converted to an interband transition in graphene. The reflectance of the DM could be further enhanced by increasing the Bragg periodic number. Furthermore, a large lateral shift of the reflected beam could also be induced around the DM. This study may find great applications in highly sensitive sensors.

scholarly journals Unidirectional Invisibility Induced by Complex Anti-Parity–Time Symmetric Periodic Lattices

2019 ◽  
Vol 9 (18) ◽  
pp. 3808 ◽  
Author(s):  
Hui Cao ◽  
Dong Zhao ◽  
Ming Fang ◽  
Huang Guo ◽  
Yonghong Hu ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Parameter Space ◽  
Frequency Band ◽  
Angular Frequency ◽  
Lateral Shift ◽  
The Other ◽  
Wide Frequency Band ◽  
Highly Sensitive ◽  
Highly Sensitive Sensors

Complex anti-parity-time symmetric periodic lattices, in a wide frequency band, can act as unidirectional invisible media. The reflection from one end is suppressed while it is enhanced from the other. Furthermore, unidirectional laser points (ULPs) which correspond to the poles of reflection from one end, arise in the parameter space composed of the permittivity and angular frequency. The phase of the reflection coefficient changes sharply near the ULPs. Subsequently, large lateral shift which is proportional to the slope of phase could be induced for the reflected beam. The study may find great applications in unidirectional invisibility, unidirectional lasers and highly sensitive sensors.

Development of FETs and Resistive Devices Based on Epitaxially Grown Single Layer Graphene on SiC for Highly Sensitive Gas Detection

2012 ◽  
Vol 717-720 ◽  
pp. 687-690
Author(s):  
Ruth Pearce ◽  
R. Yakimova ◽  
L. Hultman ◽  
Jens Eriksson ◽  
Mike Andersson ◽  
...  
Keyword(s):  
Work Function ◽  
Elevated Temperatures ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Steady Increase ◽  
Fermi Level Pinning ◽  
Layer Graphene ◽  
Highly Sensitive ◽  
Grown Graphene ◽  
P Type

Epitaxially grown single layer graphene on silicon carbide (SiC) resistive sensors were characterised for NO2 response at room and elevated temperatures, with an n-p type transition observed with increasing NO2 concentrations for all sensors. The concentration of NO2 required to cause this transition varied with different graphene samples and is attributed to varying degrees of substrate induced Fermi-level pinning above the Dirac point. The work function of a single layer device demonstrated a steady increase in work function with increasing NO2 concentration indicating no change in reaction mechanism in the concentration range measured despite a change in sensor response direction. Epitaxially grown graphene device preparation is challenging due to poor adhesion of the graphene layer to the substrate. A field effect transistor (FET) device is presented which does not require wire bonding to contacts on graphene.

scholarly journals Highly sensitive UVA and violet photodetector based on single-layer graphene-TiO_2 heterojunction

2016 ◽  
Vol 24 (23) ◽  
pp. 25922 ◽  
Author(s):  
Feng-Xia Liang ◽  
Deng-Yue Zhang ◽  
Jiu-Zhen Wang ◽  
Wei-Yu Kong ◽  
Zhi-Xiang Zhang ◽  
...  
Keyword(s):  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene ◽  
Highly Sensitive

scholarly journals Highly Sensitive Uric Acid Detection Based on a Graphene Chemoresistor and Magnetic Beads

Biosensors ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 304
Author(s):  
Wangyang Zhang ◽  
Xiaoqiang Zhao ◽  
Lina Diao ◽  
Hao Li ◽  
Zhonghao Tong ◽  
...  
Keyword(s):  
Uric Acid ◽  
High Performance ◽  
Magnetic Beads ◽  
Point Of Care ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Test Time ◽  
Film Material ◽  
Ph Change ◽  
Highly Sensitive

In this study, we developed a low-cost, reusable, and highly sensitive analytical platform for the detection of the human metabolite uric acid (UA). This novel analysis platform combines the graphene chemoresistor detection technique with a magnetic bead (MB) system. The heterojunction (single-layer graphene and HfO2 thin-film material) of our graphene-based biosensor worked as a transducer to detect the pH change caused by the specific catalytic reaction between UA and uricase, and hence acquires a UA concentration. Immobilization of uricase on MBs can decouple the functionalization steps from the sensor surface, which allows the sensor to be reusable. Our microsensor platform exhibits a relatively lower detection limit (1 μM), high sensitivity (5.6 mV/decade), a linear range (from 1 μM to 1000 μM), and excellent linearity (R2 = 0.9945). In addition, interference assay and repeatability tests were conducted, and the result suggests that our method is highly stable and not affected by common interfering substances (glucose and urea). The integration of this high-performance and compact biosensor device can create a point-of-care diagnosis system with reduced cost, test time, and reagent volume.

scholarly journals Exceptional Points in Non-Hermitian Photonic Crystals Incorporated With a Defect

2020 ◽  
Vol 10 (3) ◽  
pp. 823 ◽  
Author(s):  
Fangmei Liu ◽  
Dong Zhao ◽  
Hui Cao ◽  
Bin Xu ◽  
Wuxiong Xu ◽  
...  
Keyword(s):  
Reflection Coefficient ◽  
Photonic Crystals ◽  
Perfect Absorption ◽  
Complex Phase ◽  
One Dimensional ◽  
Exceptional Points ◽  
Coherent Perfect Absorption ◽  
Highly Sensitive ◽  
Gain Loss ◽  
Highly Sensitive Sensors

We explored exceptional points (EPs) in one dimensional non-Hermitian photonic crystals incorporated with a defect. The defect was asymmetric with respect to the center. Two EPs could be derived by modulating the normalized frequency and the gain-loss coefficient of defect. The reflection coefficient complex phase changed dramatically around EPs, and the change in complex phase was π at EPs. The electric field of EPs was mainly restricted to the defect, which can induce a giant Goos–Hänchen (GH) shift. Moreover, we found a coherent perfect absorption-laser point (CPA-LP) in the structure. A giant GH shift also existed around the CPA-LP. The study may have found applications in highly sensitive sensors.

Coherent Perfect Absorption Laser Points in One-Dimensional Anti-Parity–Time-Symmetric Photonic Crystals

2019 ◽  
Vol 9 (13) ◽  
pp. 2738 ◽  
Author(s):  
Huiling Wang ◽  
Weihao Kong ◽  
Pu Zhang ◽  
Zhongming Li ◽  
Dong Zhong
Keyword(s):  
Photonic Crystals ◽  
Loss Factor ◽  
Angular Frequency ◽  
Sharp Change ◽  
Perfect Absorption ◽  
Reflection And Transmission ◽  
Coherent Perfect Absorption ◽  
Highly Sensitive ◽  
Gain Loss ◽  
Highly Sensitive Sensors

We investigate the coherent perfect absorption laser points (CPA-LPs) in anti-parity–time-symmetric photonic crystals. CPA-LPs, which correspond to the poles of reflection and transmission, can be found in the parameter space composed of gain–loss factor and angular frequency. Discrete exceptional points (EPs) split as the gain–loss factor increases. The CPA-LPs sandwiched between the EPs are proved to be defective modes. The localization of light field and the bulk effect of gain/loss in materials induce a sharp change in phase of the reflection coefficient near the CPA-LPs. Consequently, a large spatial Goos–Hänchen shift, which is proportional to the slope of phase, can be achieved around the CPA-LPs. The study may find great applications in highly sensitive sensors.

A Highly Sensitive Hydrogen Sensor with Gas Selectivity Using a PMMA Membrane-Coated Pd Nanoparticle/Single-Layer Graphene Hybrid

2015 ◽  
Vol 7 (6) ◽  
pp. 3554-3561 ◽  
Author(s):  
Juree Hong ◽  
Sanggeun Lee ◽  
Jungmok Seo ◽  
Soonjae Pyo ◽  
Jongbaeg Kim ◽  
...  
Keyword(s):  
Single Layer ◽  
Hydrogen Sensor ◽  
Single Layer Graphene ◽  
Pd Nanoparticle ◽  
Layer Graphene ◽  
Highly Sensitive ◽  
Gas Selectivity
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