High-sensitivity broadband micro-Michelson-interferometer based on an end-sphered hollow-core fiber

Author(s):  
Nan-Kuang Chen ◽  
Kuan-Yi Lu ◽  
Chinlon Lin
Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 318
Author(s):  
Chi Li ◽  
Meng Zhu ◽  
Peng Ji ◽  
Cong Xiong ◽  
Changrui Liao

A fiber optic whispering gallery mode (WGM) resonator was proposed and realized by integrating an inline polymer waveguide with a microsphere mounted on it. The polymer waveguide with a diameter of 1 μm was printed with femtosecond laser-assisted multiphoton polymerization in a section of a grooved hollow-core fiber, which was sandwiched between two single-mode fibers. Two WGW resonators assembled with microspheres of different sizes were prepared. The transmission spectra of those stimulated WGMs were investigated both in simulation and experimentally. The temperature response of the resonators was particularly studied, and a linear sensitivity of −593 pm/°C was achieved from 20 °C to 100 °C.


2021 ◽  
Vol 11 (15) ◽  
pp. 7103
Author(s):  
Weihao Lin ◽  
Shengjie Zhou ◽  
Yibin Liu ◽  
Mang I. Vai ◽  
Liyang Shao

An optical fiber temperature sensor based on Mach–Zehnder interferometer and thermo-optic effect of the liquid crystal (LC) in fiber ring laser (FRL) system is proposed and experimentally demonstrated. The LC is infiltrated into the core of hollow core fiber, and the resonant wavelength is more sensitive to temperature variation due to the interaction between the incident light and the cavity infiltrating liquid crystal with high thermal light coefficient. Meanwhile, the FRL system was further used to make the sensor have good performance in the case of high signal-to-noise ratio (∼35 dB), narrow half-height width (FWHM = 0.15 nm), and high sensitivity in the temperature range from 20 °C to 50 °C, with the maximum sensitivity of 1.318 nm/°C. As far as we know, in the FRL system, the liquid crystal material has a better temperature sensing performance than the previous fiber. Nevertheless, the system has the advantages of good repeatability, low cost, simple production, small volume, high sensitivity. In marine microbial culture and detection, it is necessary to carry out high sensitivity measurement within a small temperature variation range. This reliable and excellent temperature performance has a potential application prospect.


Author(s):  
Sijie He ◽  
Yushan Liu ◽  
Wenlin Feng ◽  
Bangxin Li ◽  
Xiao-Zhan Yang ◽  
...  

Abstract A carbon monoxide sensor based on Michelson interferometer combined with α-Fe2O3/rGOQDs composite film is proposed and fabricated. First, a waist-enlarged taper is formed between the single-mode fiber (SMF) and the no-core fiber (NCF), then the other end of the NCF is spliced with a section of thin-core fiber (TCF). Besides, the end of the TCF is coated with a layer of silver film to enhance the reflection. Thus, the Michelson interferometer of SMF-NCF-TCF is formed. The α-Fe2O3/rGOQDs composite film is deposited on the outside surface of TCF. The specific adsorption of carbon monoxide by the composite film leads to the change of the sensor’s effective refractive index (RI), realizing the detection of carbon monoxide. The results show that the interference intensity of the monitoring valley decreases with the increase of the concentration of carbon monoxide. The sensitivity of the sensor is 0.057 dBm/ppm, the detection limit of the sensor is 105 ppb, and the response time and recovery time are 70 s and 100 s, respectively. The sensor has the advantages of high sensitivity, high selectivity and simple structure, and it is expected to be applied for the detection of carbon monoxide gas with low concentration.


Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 111
Author(s):  
Haijin Chen ◽  
Xuehao Hu ◽  
Meifan He ◽  
Qianqing Yu ◽  
Zhenggang Lian ◽  
...  

We demonstrate a dual-core fiber-based Mach–Zehnder interferometer that could be used for precise detection of variations in refractive indices of gaseous samples. The fiber used here have a solid germanium-doped silica core and an air core that allows gases to flow through. Coherent laser beams are coupled to the two cores, respectively, and thus excite guiding modes thereby. Interferogram would be produced as the light transmitted from the dual cores interferes. Variations in refractive index of the hollow core lead to variations in phase difference between the modes in the two cores, thus shifting the interference fringes. The fringe shifts can be then interrogated by a photodiode together with a narrow slit in front. The resolution of the sensor was found to be ~1 × 10−8 RIU, that is comparable to the highest resolution obtained by other fiber sensors reported in previous literatures. Other advantages of our sensor include very low cost, high sensitivity, straightforward sensing mechanism, and ease of fabrication.


2021 ◽  
pp. 127279
Author(s):  
Lifeng Bao ◽  
Xinyong Dong ◽  
Perry Ping Shum ◽  
Changyu Shen

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3763 ◽  
Author(s):  
Luis A. Herrera-Piad ◽  
Iván Hernández-Romano ◽  
Daniel A. May-Arrioja ◽  
Vladimir P. Minkovich ◽  
Miguel Torres-Cisneros

In this paper, we propose and experimentally demonstrate a simple technique to enhance the curvature sensitivity of a bending fiber optic sensor based on anti-resonant reflecting optical waveguide (ARROW) guidance. The sensing structure is assembled by splicing a segment of capillary hollow-core fiber (CHCF) between two single-mode fibers (SMF), and the device is set on a steel sheet for measuring different curvatures. Without any surface treatment, the ARROW sensor exhibits a curvature sensitivity of 1.6 dB/m−1 in a curvature range from 0 to 2.14 m−1. By carefully coating half of the CHCF length with polydimethylsiloxane (PDMS), the curvature sensitivity of the ARROW sensor is enhanced to −5.62 dB/m−1, as well as an increment in the curvature range (from 0 to 2.68 m−1). Moreover, the covered device exhibits a low-temperature sensitivity (0.038 dB/°C), meaning that temperature fluctuations do not compromise the bending fiber optic sensor operation. The ARROW sensor fabricated with this technique has high sensitivity and a wide range for curvature measurements, with the advantage that the technique is cost-effective and easy to implement. All these features make this technique appealing for real sensing applications, such as structural health monitoring.


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