1. Performance Comparison of High Index Ring Defected Core PCF Air Sensor
Veerpal Kaur, Surinder Singh
Department of Electronics and Communication, Sant Longowal Institution of Engineering and Technology, Longowal (Punjab),India
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Abstract
Figure 5 shows the relative sensitivity curve as a function of wavelength. Relative sensitivity increases sharply till the wavelength is 1µm; then we find a gradual increase for rest of the wavelengths, the sensitivity becomes higher for longer wavelength input. Similarly, Figure 6 shows confinement loss which increases with increase in wavelength. This is due leaky mode present into cladding region and show narrow dip at specific wavelength with minimum loss 1.825×10-9, ×10-7 for GeO2 and P2O5 doped silica ring.
In this paper, PCF sensor performance evaluated by adding high index material likes GeO2 and P2O5 around a hollow core. Results show that GeO2 doped silica has better performance as compared to P2O5. .
Overview of PCF based sensing mechanism
Figure 1. Cross sectional view of the proposed PCF.
Figure 2. FEM Meshed structure
Sensing Mechanism
Photonic Sensing
Simulation and Numerical Analysis
Absorbance
Reflectance
Luminescence
Fluorescence
Refractive Index
Light Scattering
Figure5.Relative Sensitivity verses wavelength
The propagation characteristics were measured using Finite Element Method (FEM). The Perfectly Matched Layer (PML) was used as the boundary condition of the PCF. Figure 2 shows the Mesh formation of the computational region of the proposed PCF which is divided into homogeneous triangular subspaces. The eigenvalue equation of the proposed C-PCF can be solved in the fundamental mode. During the propagation of light fundamental mode of light was considered for this analysis. Figure 3 represents the calculated poynting flux of fundamental mode and cladding mode of the proposed structure.
Figure6.Confinment loss verse wavelength
Fabrication
Introduction
Stack and Draw Technique
Selective filling Technique
Sol-gel Technique
Chemical Vapor Deposition Technique
During the last decade, photonic crystal fiber becomes a potential nominee in the sensor field due to its most intriguing structure for sensing application. Advance technology support unique sensing properties by modifying its size, structure and arrangement of air hole in core cladding region [1]. Photonic sensor has tremendous interest for detecting various species like toxic gases, liquid, bacteria and disease tissues [2, 3]. Hollow core PCF has high sensitivity, narrow transmission spectra and needed precise arrangement of air holes [4]. Further, solid core PCF becomes premium candidate to overcome the above limitation with low sensitivity [5]. Many researchers have reported to enhance the sensitivity of index guided PCF by different designs. In this respect, we use circular photonic crystal fiber with high index P2O5 and GeO2 doped silica ring around the core and analyzed sensor performance.
A FEM based simulation tool COMSOL Multiphysics 4.3a has been used to simulate the proposed structure. The detection technique of any chemical analyte by the proposed PCF is the absorption method. The absorption of the sample to be detected is defined as;
The relative sensitivity coefficient r is defined by the following equation;
Where, the power distribution function f is called the percentage of energy in the hole. Silica considered as background material by using the sellmeier equation.
Figure 3.(a)Fundamental mode Figure 3.(b).Cladding mode
Conclusion
This proposed sensor has maximum relative sensitivity around 55% and lowest confinement loss 1.825×10-9, ×10-7 for GeO2 and P2O5 doped silica ring at 0.9µm and 0.8 µm wavelength. This proposed sensor used for various liquid and gas sensing application with wide range of operating wavelength from 0.5 to 2.0 µm.
Future Work A B
Research Methodology
It is done theoretically only. The proposed PCF based gas and chemical sensor will be fabricated practically.
In future, We will try to employ PCF sensor for industrial safety purposes by sensing toxic and flammable gases and liquids.
Much more work should be done for achieving higher sensitivity and lower confinement losses.
An acute literature has been surveyed on different design of hollow core PCF used for sensing application. The literature survey indicates hollow core with high index ring based sensor has maximum sensitivity and minimum confinement loss. For smart sensor design, following research methodology designed
Design the microstructure fiber and core filled with sensing liquid (water, ethanol, benzene)
Analysed the performance with respect to operating wavelength.
Result and Discussion
The performance analysis of the proposed C-PCF has been done at a wide range of wavelength from 0.5 µm to 2.0 µm. The index profile of the proposed sensor has been shown in the Figure4.It shows that real part of effective refractive index decreases with increase in wavelength for both GeO2 and P2O5 doped silica as follow the sellimeier formula.
References
S. Yin, “Fiber Optic Sensors”, Taylor & Francis Group, CRC Press, 2nd Ed. (2008).
J.B.Jensen, A.Bjarklev, P.E.Hoiby, G.Emiliyano, O.Bang, L.H.Pedersen, “Selective detection of antibodies in micro structured polymer optical fiber,” Opt.Expres 13, (2005).
Kawsar Ahmed,M.Morshed, “Design and numerical analysis of microstructured-core octagonal photonic crystal fiber for sensing application,” Sensor &Biosensor Research 7, 1-6 (2016).
J. M. Fini, “Microstructure fibers for optical sensing in gases and liquids,” Measurement Science and Technology 15, 1120–1128 (2004).
S. Olyaee and A. Naraghi, “Design and optimization of index-guiding photonic crystal fiber gas sensor,” Photonic Sensor 3, 131–136 (2013).
Proposed Structure
The proposed C-PCF has been designed with circular arrangement of air holes around the high index ring. The micro channel at centre have been filled with the air and surrounded with high index material like P2O5 and GeO2. .Figure 1 represents the cross sectional view of the proposed C-PCF structure. The diameter of the air holes at core and cladding d=1.70 µm and width of high index ring is µm. The pitch distance and it has been assumed as Ʌ= 3.50µm for the cladding air holes.
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Figure 4. Effect Refractive index verse wavelength