1. Hybrid Design of Photonic Crystal Fiber Sensor for Lower Indexed Chemicals
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. Higher relative sensitivity %, % and % for water ethanol and benzene. 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 ×10-8 (dB/m), ×10-8 (dB/m) and ×10-9 (dB/m) for water, ethanol and benzene. .
In this paper, hybrid photonic crystal fiber (H-PCF) sensor performance analyzed by adding horizontal elliptical air hole at center. The sensor has maximum sensitivity % and minimum confinement loss ×10-9 (dB/m) for Benzene chemical. .
Overview of PCF based sensing mechanism
Figure 2. FEM Meshed structure
Figure1. Cross sectional view of the proposed hybrid PCF.
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 PCF can be solved in the hybrid mode . During the propagation of light hybrid mode considered for this analysis. Figure 3 represents the calculated poynting flux of hybrid x and y modes.
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.
Figure3(a).X polarized mode HE Figure(3b). Y polarized mode HE11
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.
Conclusion
This proposed sensor has maximum relative sensitivity around %, % and % minimum confinement losses are ×10-8 (dB/m), ×10-8 (dB/m) and ×10-9 (dB/m) for water, ethanol and benzene. 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 Objective
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 PCF used for sensing application. The literature survey indicates microstructure fiber with holy core based sensor has maximum sensitivity and minimum confinement loss. Following are research objective:
. To Introduce hybrid design of PCF .
To analysis the sensing performance for different chemicals
Result and Discussion
The performance analysis of the proposed H-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 three different chemical like water(1.330), ethanol(1.354) and benzene(1.360).
References
Proposed Structure
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).
Our proposed H-PCF contains five layers of air hole with circular arrangement in cladding and horizontal directed elliptical air hole in core region. This proposed structure consist 8, 24, 30, 36 and 30 air hole in respective layer in cladding and 17 horizontal directed elliptical air hole present in core region. The pitch between adjacent first two layer 1.75 µm, other layer has 1.50 µm and ellipticity constant (ratio of major axis to minor axis) of core hole is Core holes filled various low indexed chemicals such as water, ethanol and benzene. Refractive index of various sensing like water, ethanol and benzene is 1.330,1.354 and respectably.
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Figure 4. Effect Refractive index verse wavelength