Sensors|3 Article(s)
Fiber loop ring-down cavity integrated U-bent single-mode-fiber for magnetic field sensing
Yaofei Chen, Tiegen Liu, Qun Han, Wenchuan Yan, and Lin Yu
A novel magnetic field sensing system based on the fiber loop ring-down technique is proposed in this paper. In the fiber loop, a U-bent single-mode-fiber structure coated with magnetic fluid (MF) serves as the sensing head, and an erbium-doped fiber amplifier (EDFA) is introduced to compensate for the intrinsic loss of the cavity. The ring-down time of the system varies with the change of applied magnetic field due to the tunable absorption coefficient and refractive index of the MF. Therefore, measurement of the magnetic field can be realized by monitoring the ringdown time. The experimental results show that the performance of the system is extremely dependent on the interrogation wavelength, because both the gain of the EDFA and the loss of the sensing head are wavelength dependent. We found that at the optimal wavelength, the ratio of the gain to loss attained its maximum. The sensing system was experimentally demonstrated and a sensitivity of ?0.5951 μs∕Oe was achieved.61107035).
Photonics Research
  • Publication Date: Nov. 15, 2016
  • Vol. 4, Issue 6, 06000322 (2016)
Sensitivity-enhanced surface plasmon resonance sensor utilizing a tungsten disulfide (WS2) nanosheets overlayer
Hao Wang, Hui Zhang, Jiangli Dong, Shiqi Hu, Wenguo Zhu, Wentao Qiu, Huihui Lu, Jianhui Yu, Heyuan Guan, Shecheng Gao, Zhaohui Li, Weiping Liu, Miao He, Jun Zhang, Zhe Chen, and Yunhan Luo
Tungsten disulfide (WS2), as a representative layered transition metal dichalcogenide (TMDC) material, possesses important potential for applications in highly sensitive sensors. Here, a sensitivity-enhanced surface plasmon resonance (SPR) sensor with a metal film modified by an overlayer of WS2 nanosheets is proposed and demonstrated. The SPR sensitivity is related to the thickness of the WS2 overlayer, which can be tailored by coating a WS2 ethanol suspension with different concentrations or by the number of times of repeated post-coating. Benefitting from its large surface area, high refractive index, and unique optoelectronic properties, the WS2 nanosheet overlayer coated on the gold film significantly improves the sensing sensitivity. The highest sensitivity (up to 2459.3 nm/RIU) in the experiment is achieved by coating the WS2 suspension once. Compared to the case without a WS2 overlayer, this result shows a sensitivity enhancement of 26.6%. The influence of the WS2 nanosheet overlayer on the sensing performance improvement is analyzed and discussed. Moreover, the proposed WS2 SPR sensor has a linear correlation coefficient of 99.76% in refractive index range of 1.333 to 1.360. Besides sensitivity enhancement, the WS2 nanosheet overlayer is able to show additional advantages, such as protection of metal film from oxidation, tunability of the resonance wavelength region, biocompatibility, capability of vapor, and gas sensing.
Photonics Research
  • Publication Date: Apr. 26, 2018
  • Vol. 6, Issue 6, 06000485 (2018)
Chip-scale broadband spectroscopic chemical sensing using an integrated supercontinuum source in a chalcogenide glass waveguide
Qingyang Du, Zhengqian Luo, Huikai Zhong, Yifei Zhang, Yizhong Huang, Tuanjie Du, Wei Zhang, Tian Gu, and Juejun Hu
On-chip spectroscopic sensors have attracted increasing attention for portable and field-deployable chemical detection applications. So far, these sensors largely rely on benchtop tunable lasers for spectroscopic interrogation. Large footprint and mechanical fragility of the sources, however, preclude compact sensing system integration. In this paper, we address the challenge through demonstrating, for the first time to our knowledge, a supercontinuum source integrated on-chip spectroscopic sensor, where we leverage nonlinear Ge22Sb18Se60 chalcogenide glass waveguides as a unified platform for both broadband supercontinuum generation and chemical detection. A home-built, palm-sized femtosecond laser centering at 1560 nm wavelength was used as the pumping source. Sensing capability of the system was validated through quantifying the optical absorption of chloroform solutions at 1695 nm. This work represents an important step towards realizing a miniaturized spectroscopic sensing system based on photonic chips.
Photonics Research
  • Publication Date: Apr. 26, 2018
  • Vol. 6, Issue 6, 06000506 (2018)