A Large Detection-Range Plasmonic Sensor Based on An H-Shaped Photonic Crystal Fiber

Abstract

An H-shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed for detecting large refractive index (RI) range which can either be higher or lower than the RI of the fiber material used. The grooves of the H-shaped PCF as the sensing channels are coated with gold film and then brought into direct contact with the analyte, which not only reduces the complexity of the fabrication but also provides reusable capacity compared with other designs. The sensing performance of the proposed sensor is investigated by using the finite element method. Numerical results show that the sensor can work normally in the large analyte RI (n a ) range from 1.33 to 1.49, and reach the maximum sensitivity of 25,900 nm/RIU (RI units) at the n a range 1.47-1.48. Moreover, the sensor shows good stability in the tolerances of ±10% of the gold-film thickness.

Overview of Recent Advances in the Design of Plasmonic Fiber-Optic Biosensors

“…While the detection range of this biosensor was more limited comparing to [37], the main advantages of this biosensor were utilizing a cost-effective material (titanium nitride) instead of gold, and also showing a higher sensitivity and figure of merit comparing to gold-based D-shaped PCF biosensors. As PCF is an extremely flexible platform for realizing different design concepts, a major diversity in terms of the possible designs for plasmonic biosensors based on PCFs can be seen in the literature [42][43][44]. In contrast to the common D-shaped and H-Shaped PCFs, in 2019, Chu et al [42] proposed…”

“…As PCF is an extremely flexible platform for realizing different design concepts, a major diversity in terms of the possible designs for plasmonic biosensors based on PCFs can be seen in the literature [42][43][44]. In contrast to the common D-shaped and H-Shaped PCFs, in 2019, Chu et al [42] proposed a six-fold PCF-based plasmonic biosensor with a trapezoidal analyte channel and gold layer for the detection of high RI liquid analytes.…”

“…A generalized cross-sectional view of the trapezoidal-channel PCF-based biosensors is illustrated in Figure 17a. H-shaped PCFs is another fiber geometry that demonstrated potential for designing highly accurate and ultra-sensitive plasmonic biosensors [44]. The cross-sectional view of plasmonic Hshaped PCF biosensors are demonstrated in Figure 17c.…”

“…The possible experimental setup, three-dimensional diagram of the sensor and the cross-sectional view of the fiber probe is illustrated in Figure 18. According to Figure 18, the grooves of their proposed H-shaped PCF as the sensing channels are coated with gold nanofilms and then brought into direct contact with the analyte [44]. Interestingly, the analyte RI in this design can be either higher or lower than that of the fiber materials, which is a definite advantage of this design over the similar plasmonic fiber-optic probes.…”

A Highly Magnetic Field Sensitive Photonic Crystal Fiber Based on Surface Plasmon Resonance

“…The main reason is that with the continuous increase of n a , the difference between the overall refractive index of the photonic crystal fiber and the refractive index of the central air hole increases, and the excited SPP mode is enhanced. Sensitivity is an important parameter of the sensor, which describes the change of the resonant wavelength of the sensor to the unit refractive index, which can be defined, as [ 35 ]: where Δ λ peak is the distance of the loss peak drift and Δn a is the change value of the refractive index of the central air hole. The inset in Figure 7 shows the change in the resonant wavelength of the refractive index of n a between 1.43 and 1.45.…”