Enhancement of the sensitivity of gas sensor based on microstructure optical fiber

Abstract

This paper proposes the design and characterization of microstructure optical fiber for gas sensing applications. The aim is to detect toxic and colorless gases over a wide transmission band covering 0.80 m to 2.00 m wavelength. Numerical investigation is carried out by using the finite element method (FEM). The numerical study shows that sensitivity of the proposed sensor is moderately increased by introducing four non-circular holes around the defected core of photonic crystal fiber and the confinement loss is also reduced. Furthermore, we confirm that increasing the diameter of central air core and size of the non-circular holes can improve the relative sensitivity and the confinement loss is reduced by increasing the diameter of air holes in the cladding. The enhancement of the relative sensitivity is more than 27.58% (0.1323 to 0.1688) at the wavelength =1.33m that is the absorption line of methane (CH 4 ) and hydrogen fluoride (HF) gases. The confinement loss of the fiber is 1.765×10 8 dB/m.

Design and optimization of photonic crystal fiber for liquid sensing applications

“…Perfectly matched layer (PML) is used as a boundary condition. Thickness of the PML is fixed to 10% of the radius of the proposed PCFs for efficient calculation of confinement loss [29]. …”

Design and optimization of photonic crystal fiber based sensor for gas condensate and air pollution monitoring

“…The micro-structured core PCFs help gain higher relative sensitivity and alleviate confinement loss [36]. Besides, it can be analyzed that the relative sensitivity is promoted with the enhancement of air holes diameter in the core region and decrement of pitch Λ c [30]. Figure 5 shows 4 dB/m, respectively.…”

“…It can be seen that 56.65% relative sensitivity as well as 2.31×10 5 dB/m confinement loss can be obtained at the operating wavelength of 1.33 m. From the observation, it can be seen that the proposed H-PCF has a higher relative sensitivity compared with prior PCFs [14,[30][31][32]34]. For the central air holes, when enough light would be confined into the cladding region and interaction happens between light and gases, then sensitivity will be increased [31].…”

“…The variation of pitch () has great effect on relative sensitivity. High sensitivity makes the fiber more practical in the sensing applications like toxic and colorless gas detection [30]. The relative sensitivity versus wavelength curve for variations of pitch () of cladding is depicted in Fig.…”

“…In 2003, Hoo et al [29] reported an all-fiber gas sensor and obtained the relative sensitivity of 10.15% at the 1.4 m wavelength. The improvement of relative sensitivity of 16.88% and the reduced confinement loss of 1.765×10 8 dB/m have been done by Morshed et al [30]. In [31], it suggested an index-guiding PCF and achieved the sensitivity and leakage loss of 29.80% and 4.50×10 1 dB/m, respectively.…”