Recent Developments in Micro-Structured Fiber Optic Sensors

Abstract:The temperature sensitivity of the free spectral range (FSR) for a polymer-overlaid microfiber Mach-Zehnder interferometer (MZI) is investigated both theoretically and experimentally. The waist diameter of the optical microfiber can be controlled to alter the thermal expansion and optic properties of the polymer-coated MZI. Inserting an optical microfiber with a strong evanescent field into the MZI, a low index polymer with high thermal characteristics is deposited on the surface of the microfibers to realize a polymer-overlaid microfiber MZI. It was found that the thermal expansion factor in the proposed MZI plays an important role in the temperature sensitivity of the FSR. The temperature sensitivity of the polymer-overlaid microfiber MZI is improved, which is measured to be −8.29 nm/ • C at 25 • C. The optical transmission spectrum of the polymer-overlaid microfiber MZI is converted to the spatial frequency spectrum via fast Fourier transform. The temperature sensitivity of the spatial frequency in the proposed polymer-overlaid MZI is estimated to be 18.31 pm −1 • C −1 , which is 17 times higher than that of the microfiber MZI without polymer coating (1.04 pm −1 • C −1 ).

Section: Fabrication Of the Polymer-overlaid Microfiber Mzimentioning

confidence: 99%

Investigation of Temperature Sensitivity of a Polymer-Overlaid Microfiber Mach-Zehnder Interferometer

Han

2017

“…As a basic optical parameter, the refractive index (RI) can be widely used to identify chemical substances in many analytical applications, including food safety [ 1 ], medical examination [ 2 , 3 ], and environmental monitoring [ 4 , 5 ]. In the past few decades, the fiber-based RI sensor has been extensively explored because of its advantages of low cost, multiplexing capability, and fast response.…”

Section: Introductionmentioning

confidence: 99%

Refractive Index Sensor Based on Double Side-Polished U-Shaped Plastic Optical Fiber

Wang

Zhang

et al. 2020

A U-shaped double-side polished plastic optical fiber (POF) is demonstrated as a liquid refractive index (RI) sensor. The refractive index of glycerinum solutions is identified by the intensity detection on the bending and evanescent wave loss change. Heat treatment and mechanical polishing are adopted to form the symmetrical side-polished POF probe. The processing parameters are experimentally optimized on the power transmittance. The sensitivity of 1541%/RIU (Refractive Index Unit) can be obtained with a resolution of 5.35 × 10−4 in the scope of 1.33–1.39. The favorable temperature characteristic is proved to offer stable RI sensing from 20 to 50 °C. This simple POF sensor has potentials in low-cost visible light intensity RI detection.

“…As a combination of fibre optics and nanotechnology, mocro-/nanostructurization of optical fibres has been an important trend for exploring fibre-optic sensing technology on the micro or nanoscale [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. It is obvious that, reducing the size of a sensing structure is usually an essential step to bestow the sensor with higher sensitivity, faster response, lower power consumption and better spatial resolution, and the optical micro/nanofibre (MNF) became one of the best candidates for this purpose.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, rapid progress has been made in the field of MNF-based optical sensors, as have been summarized in a number of books and review articles [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. In this tutorial, besides the basic introduction to MNF optics for optical sensors, we will review the up-to-date progresses in this field, and some of their closely related techniques.…”

Section: Introductionmentioning

confidence: 99%

Micro/Nanofibre Optical Sensors: Challenges and Prospects

Tong

2018

Micro/nanofibres (MNFs) are optical fibres with diameters close to or below the vacuum wavelength of visible or near-infrared light. Due to its wavelength- or sub-wavelength scale diameter and relatively large index contrast between the core and cladding, an MNF can offer engineerable waveguiding properties including optical confinement, fractional evanescent fields and surface intensity, which is very attractive to optical sensing on the micro and nanometer scale. In particular, the waveguided low-loss tightly confined large fractional evanescent fields, enabled by atomic level surface roughness and extraordinary geometric and material uniformity in a glass MNF, is one of its most prominent merits in realizing optical sensing with high sensitivity and great versatility. Meanwhile, the mesoporous matrix and small diameter of a polymer MNF, make it an excellent host fibre for functional materials for fast-response optical sensing. In this tutorial, we first introduce the basics of MNF optics and MNF optical sensors, and review the progress and current status of this field. Then, we discuss challenges and prospects of MNF sensors to some extent, with several clues for future studies. Finally, we conclude with a brief outlook for MNF optical sensors.