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Effective Refractive Index for background materials like a Teflon glass, b BK7 glass, c silica glass for the wavelength between 1.4 and 1.65 µm
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A low confinement loss of hollow-core photonic crystal Fiber (HC-PCF) for liquid-/gas-sensing applications has been proposed. Various HC-PCF backgrounds such as silica, BK7 and Teflon glass with different core materials such as glycerol, benzene and toluene have been studied using a finite element method with perfectly matched layer-based COMSOL so...
Citations
... Frequencies in the terahertz range, the range between microwave and infrared waves (0.1THz-10THz) have gained considerable importance because of the potential applications in medical diagnostics, tomography, covert detection, defense, astronomy, imaging of hidden objects, and detection of explosives [12][13][14][15][16]. Although THz waves cause a lot of losses in metal, glass, water, dust, fog, and clouds, they have unique characteristics-the ability to penetrate dry air, plastics, fabrics, ceramics, etc.-that are not found in other electromagnetic band waves [17][18][19][20][21]. THz waves can also have less biological hazard, which make them suitable for applications such as remote sensing, medical imaging, conduction with limited diffraction, remote broadband communication, and so on [22][23][24][25][26][27]. ...
In the present study, a photonic crystal fiber with a simple design and low losses in the range of terahertz broadband pulse was designed. The proposed structure of this study consisted of a large central air core arranged by three rings of air holes in a regular hexagonal pattern in a uniform Teflon matrix. The refractive index of Teflon, which was made of polymer, was 1.44. The conduction in this fiber was achieved using photonic band gap (PBG) only for a certain range of non-zero values. The simulation results showed that at the wavelength of 174 µm with a central hole diameter of 2.9Ʌ (Ʌ = 300 µm), the lowest confinement losses equal to 0.2 dB/m occurred and the dispersion parameter was 1.2 ps/nm km.
... The choice of PQF structural parameters is essential in the result and structural formation. Hence, this work optimized the variations in the material thickness and geometrical parameters (diameter of air holes) for fabrication tolerance [18,19]. Fig. 2 shows that the thin film (20-−50 nm) has a higher loss depth and longer wavelength (1250 nm) for pure petrol. ...
... In applications involving the sensing of liquid, HC-MOFs provide a number of advantages over typical optical fibres, including a reduction in the amount of light that is lost, increased flexibility, and simpler selective liquid filling. Because of these factors, optical fibres may be used in previously unexplored fields of study, such as gas sensing (Senthil et al. 2021) and low-index liquid sensing in the fiber core which can have important applications in the fields like medicine and biology in which liquid sensing is of a great importance (Malinin et al. 2011a, b;Hossain 2019;Podder et al. 2020). ...
Detection of low index liquid analytes in real-time, in-situ, and with high accuracy is of great importance in various scientific fields, particularly in medicine and biology. Accurate detection of plasma concentration in blood samples is one of the most significant usages of biosensors in medicine. In this paper, we report a highly sensitive biosensor using hollow core microstructure optical fibers (HC-MOFs) to detect low index liquid analytes with a particular focus on detection of plasma concentration in blood samples. We demonstrate how variations in plasma concentration in blood can change transmission spectra of the HC-MOF due to the photonic bandgap mechanism. We use the finite element approach to explore how the biosensor's performance depends on the number of capillary rings encircling the hollow core of the fibre. An average spectral and amplitude sensitivity of 8928.57 nm/RIU and 1.21 dB/RIU is reported for the optimized design of HC-MOF for five capillary rings with a refractive index detection range of 1.333 to 1.3385 for different ratios of plasma in blood serum. The proposed biosensor can have potential application in liquid analyte detection in medicine, chemistry, and biology where real-time and accurate data about liquid analytes are necessary for human metabolism.
... Several ways have been reported to overcome this, using surface plasmon resonance (SPR) technology based on photonic crystal fiber (PCF) will be a good technique in detecting analyte samples [1], for various applications such as in the medical world [2], food safety [3], environment and biochemistry [4]. SPR sensors are widely used in glucose sensing [5], virus detection [6], gas sensing [7], blood type detection [8], environmental sensing [9], food quality measurement [10], telemedicine [11], sensing temperature [12]- [15] and antigen-antibody interactions and other biochemical applications [13]. ...
In this paper, we investigate a hexagonal two-layer photonic crystal fiber based on surface plasmon resonance (HT-PCF-SPR) which is easy to fabricate as a sensor for detecting the refractive index of analytes. After performing numerical simulations using COMSOL multiphysics based on the finite element method (FEM), it was found that the HT-PCF-SPR could detect the analyte's refractive index in the range 1.34-1.37 RIU and in the wavelength range from 730 nm to 810 nm. The plasmonic material used in the design is gold with a thickness of 40 nm which is located outside the layer and in two opposite air holes in the core. The HT-PCF-SPR design has good performance in detecting analytes, it is found that the sensitivity in detecting analytes is 2,000 nm/RIU, meaning that every 1 RIU shift of analyte shifts the wavelength by 2000 nm. Meanwhile, the sensor resolution obtained from the design is 6.67×10-5 RIU, and it is found that the larger the air hole, the greater the confinement loss value.
This paper proposes a new circular hydrostatic pressure sensor based on a dual-core photonic crystal fiber (DC-PCF) with a graphene layer that can be used in industrial and medical applications. Numerical simulations are performed using COMSOL Multiphysics software, which solves problems using the finite element method (FEM). The coupling length and confinement loss of the proposed DC-PCF are calculated at a wavelength of 1.55 μm, which are 1.291 mm and 2.3362 × 10–3 dB/m, respectively. A linear relationship is observed between the applied pressure and the peak wavelength of the transmission spectrum. When pressure is applied to the proposed DC-PCF from 0 to 1000 MPa, the spectrum transmission shifts to blue wavelengths. The results show that the proposed DC-PCF with a length of 6 cm has the highest sensitivity of − 30 pm/MPa. A very low value of the limit of detection (LOD) parameter of 0.785 pPa is calculated. High sensitivity and low LOD make the sensor able to measure pressure changes with high accuracy. It is also shown that adding a graphene layer to the center of the DC-PCF sensor increases the birefringence, confinement loss, and stress component values.
In this paper, a hollow-core photonic crystal fiber (PCF) composed of magnesium fluoride is designed to identify toxic and hazardous gases. Its band structure is calculated using the well-known plane wave expansion method. The numerical results show that the proposed structure has a relatively wide photonic bandgap (PBG) in the wavelength range of 1 to 3.3 μm covering the near- and mid-infrared wavelength ranges. Then, by applying optical pulses with a wavelength in the range of the PBG to the proposed PCF, its propagation behavior is calculated by solving the nonlinear Schrödinger equation using the split-step Fourier method. The type of gas can be identified by observing and comparing the frequency responses of the gas-filled PCF with the absence of gas injection. Simulation results show that the fiber proposed in this study has a sensitivity coefficient of more than 50%. The low loss, low dispersion, and high accuracy of the proposed fiber make it a suitable tool for identifying toxic and dangerous gases such as methane and hydrogen sulfide in the drilling and oil exploration industry. Identifying them using this tool prevents combustion and explosion in the drilling process.
At the present time, there are major concerns regarding global warming and the possible catastrophic influence of greenhouse gases on climate change has spurred the research community to investigate and develop new gas-sensing methods and devices for remote and continuous sensing. Furthermore, there are a myriad of workplaces, such as petrochemical and pharmacological industries, where reliable remote gas tests are needed so that operatives have a safe working environment. The authors have concentrated their efforts on optical fibre sensing of gases, as we became aware of their increasing range of applications. Optical fibre gas sensors are capable of remote sensing, working in various environments, and have the potential to outperform conventional metal oxide semiconductor (MOS) gas sensors. Researchers are studying a number of configurations and mechanisms to detect specific gases and ways to enhance their performances. Evidence is growing that optical fibre gas sensors are superior in a number of ways, and are likely to replace MOS gas sensors in some application areas. All sensors use a transducer to produce chemical selectivity by means of an overlay coating material that yields a binding reaction. A number of different structural designs have been, and are, under investigation. Examples include tilted Bragg gratings and long period gratings embedded in optical fibres, as well as surface plasmon resonance and intra-cavity absorption. The authors believe that a review of optical fibre gas sensing is now timely and appropriate, as it will assist current researchers and encourage research into new photonic methods and techniques.
A highly sensitive trapezium-shaped groove photonic crystal fiber (TSG-PCF) sensor based on surface plasmon resonance (SPR) is proposed and investigated numerically in low refractive index (RI) detection range of 1.18–1.30 by the finite element method (FEM). The trapezoidal groove is introduced, this sensor is simple in structure and manufactured easily. Indium tin oxide (ITO) is set as the sensing layer for the reaction between the core and the plasma. The influences of the structural parameters such as the holes parameters, the geometric parameters of trapezium-shaped groove, ITO layer thickness and other performance parameters on the design and sensing features of the proposed sensor are discussed comprehensively. The results show that for the proposed TSG-PCF, the maximum wavelength and amplitude sensitivity can arrive at 9100 nm/RIU and 99 RIU⁻¹, the corresponding resolutions are 1.10 × 10⁻⁵ RIU and 1.01 × 10⁻⁴ RIU respectively in the analyte RI from 1.18 to 1.30. Moreover, the average sensitivity of 3429 nm/RIU can be realized for the appropriate parameters. The highly sensitive sensor makes the wide potential development for low RI detection in biological and chemical sensing.
