During the fabrication process variations of

During the fabrication process, 1% variations of global diameters in the fiber may occur where 2% is tolerable [37]. It is clearly reported in Table 1 that there are no much changes of investigated guiding properties value for ±1% variations of global parameters. So after fabrication process, there will be little bit performance variations of proposed PCF. In a particular wavelength, each gas has its own bosentan line. To detect gasses in remote places low loss optical fibers in the near infrared region (NIR) can be used which have minimum transmission loss (<1dB/km) [23]. The absorption line of methane (CH4) and hydrogen fluoride (HF) is the wavelength of 1.33μm. In this paper, we mainly focused on these to gasses methane (CH4) and hydrogen fluoride (HF). Besides, the proposed PCF can detect the gasses of a different absorption line of a wide range of wavelength from 1.33μm to 2.2μm. For sensing application and fiber loop mirror high birefringent PCFs (HB-PCFs) are suitable. Elliptical holes provide high birefringence of PCF which has better polarization maintenance properties. Few applications like stabilizing the operation of optical devices and extinguishing the consequences of polarization mode dispersion PCFs with PM properties is needed [40]. The proposed E-PCF shows higher birefringence than the conventional PM fibers. Besides, the proposed PCF shows lower confinement loss or leakage loss. In order to decrease confinement loss, the number of rings of air holes in cladding must be increased. Additionally, confinement loss may be zero if there are infinite numbers of holes in the cladding but this scheme is not practically adjustable. Fabrication is an important and challenging issue of any photonic crystal fiber. Our proposed PCF is a dual shape mixing PCF (core holes are elliptical and cladding holes are circular). Authors believe that due to the advancement of the fabrication process of nanotechnology the proposed E-PCF can be fabricated in recent years. To gain ultrahigh birefringence such types of dual shape mixing PCF was proposed [41] in the past. To fabricate our proposed E-PCF different types of fabrication process can be used (one to fabricate core region and another to fabricate cladding region). Elliptical holes can be successfully fabricated in recent years [42]. Besides, a capillary stacking method [43] can be used to fabricate the proposed E-PCF. The sol-gel method can be used especially for fabrication of the cladding because this method allows PCF to fabricate with different holes shapes and size [44].
Conclusion We have proposed a micro-cored based photonic crystal fiber gas sensor with high sensitivity, birefringence low confinement loss consequently between the wider wavelength ranges from 1.3μm to 2.2μm. In proposed E-PCF, the core is formulated with elliptical holes. The variation of index guiding properties on the proposed fiber parameters is numerically investigated applying FEM and perfectly matched layer (PML) circular boundary condition. The proposed fiber exhibits sensitivity, birefringence, nonlinear coefficient, effective area as high as 53.07%, 6.9×10, 15.67Wkm, 3.88μm2 respectively. The higher sensitivity makes this fiber a potential candidate to detect colorless and toxic gasses as well as environment pollution monitoring. In addition, the proposed E-PCF will be helpful in other sensing applications and overcome the critical trade-off among investigated index-guiding properties. Moreover, fiber loop mirror, polarization control, four wave mixing, telecommunication application and fiber optic sensor can be the efficient uses of the accounted results.
Acknowledgment
Introduction Mercury is a highly toxic metal in all its oxidation states (0, +1 and +2). It is emitted from natural sources (e.g. volcanic eruptions) and from anthropogenic sources like coal combustion and gold mining [1,2]. Mercury is very toxic to human where it causes abnormal functions of the brain, kidney, liver, eyes and bones upon accumulation in a body [3,4]. The toxicity of mercury at low level warrants its analysis in water and other samples [5] and also its removal from the environment [6].