Etched multimode microfiber knot-type loop interferometer refractive index sensor

Pal, Sudipta Sarkar; Mondal, Samir K.; Tiwari, Umesh; Swamy, P. Venu Gopala; Kumar, Manish; Singh, Nahar; Bajpai, Phun Phun; Kapur, Pawan

doi:10.1063/1.3633955

Cited by 19 publications

(9 citation statements)

References 26 publications

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“…Pal et al first etched multimode optical fibers with hydrofluoric acid to generate knot resonators and excite interferometric spectra for refractive index measurements, observing a maximum sensitivity of 172 nm RIU −1 (refractive index unit). [100] However, the microfibers produced by this method often have poor surface quality, which can cause large optical losses. To protect the ultrafine fibers from mechanical effects and to maintain a large evanescent field, Li et al proposed a dip-coating technique, [101] where MKR is first immersed in Teflon solution, then quickly raised and dried to generate a thin and uniform film on its surface.…”

Section: Refractive Index Sensingmentioning

confidence: 99%

Microfiber Knot Resonators: Structure, Spectral Properties, and Sensing Applications

Zhang,

Gao,

Xia

et al. 2023

Laser & Photonics Reviews

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In recent years, compact micro‐/nanofiber sensors with fast response and high resolution have become a hot field in sensing and nanotechnology. In addition to the unique properties of microfibers such as strong evanescent field, low optical loss, and easy integration, microfiber knot resonators further improve the sensing capability due to their resonance properties. The potential high‐quality factor allows higher sensing sensitivity and resolution, which is very attractive for optical sensing at the micro‐/nano scale. More application potential can be effectively stimulated by improving the structure shape or principle or combining with functional sensitive materials. This paper first introduces the preparation process and spectral characteristics of conventional microfiber knots and then focuses on three new types of devices for enhancing the sensing performance, namely material‐coated, shape‐improved, and principle‐extended, and briefly analyzes their spectral properties. In addition, the research progress and applications of these sensors are summarized. Finally, the existing problems in this field are analyzed, and the directions for further development are discussed and prospected.

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Section: Refractive Index Sensingmentioning

confidence: 99%

Microfiber Knot Resonators: Structure, Spectral Properties, and Sensing Applications

Zhang,

Gao,

Xia

et al. 2023

Laser & Photonics Reviews

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“…To enhance the mechanical stability of free-standing MNF ring resonators without substrates, in 2006, Jiang et al tied a free-standing MNF into a knot [ 114 ], in which the knot structure was maintained by the friction of the microfibre at the joint area under the tension of the elastically bent knot, and was proved highly stable in water with Q factors up to 31,000 and finesse of 13. Based on MNF knot resonators, a variety of sensing structures have been reported [ 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 ]. For example, in 2009, Wu et al demonstrated a micro-electromechanical system (MEMS) based optical accelerometer combined with a 386-μm-diameter knot resonator fabricated by a 1.1-μm-diameter silica MNF [ 115 ].…”

Section: Mnf Optical Sensorsmentioning

confidence: 99%

Micro/Nanofibre Optical Sensors: Challenges and Prospects

Tong

2018

Sensors

116

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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.

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“…The experimental results showed that the microfiber accelerometer had a sensitivity of 654.7 mV/g, with a dynamic range of 20 g. In 2011, using a copper-wire-wrapped microfiber knot resonator (Figure 12), Lim et al demonstrated tuning the resonant wavelength of the microfiber resonator by applying electric current to the copper wire [68], and realized a compact current sensor with the maximum tuning slope of 51.3 pm/A 2 . Besides the above-mentioned examples, microfiber-knot-based optical sensors have also been reported for measurement of refractive index [64,69], humidity [61,70], temperature [57,69,71,72], and magnetic field [73]. Overall, as a free-standing microfiber cavity without the supporting substrate, the microfiber knot resonator offers opportunities for optical sensing with high sensitivity, fast response, high robustness and compact size in liquid and/or vibrating environment.…”

Section: Microfiber Functionalized Structures and Optical Sensorsmentioning

confidence: 99%

Microfiber Optical Sensors: A Review

Lou

Wang

Tong

2014

Sensors

220

101

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With diameter close to or below the wavelength of guided light and high index contrast between the fiber core and the surrounding, an optical microfiber shows a variety of interesting waveguiding properties, including widely tailorable optical confinement, evanescent fields and waveguide dispersion. Among various microfiber applications, optical sensing has been attracting increasing research interest due to its possibilities of realizing miniaturized fiber optic sensors with small footprint, high sensitivity, fast response, high flexibility and low optical power consumption. Here we review recent progress in microfiber optical sensors regarding their fabrication, waveguide properties and sensing applications. Typical microfiber-based sensing structures, including biconical tapers, optical gratings, circular cavities, Mach-Zehnder interferometers and functionally coated/doped microfibers, are summarized. Categorized by sensing structures, microfiber optical sensors for refractive index, concentration, temperature, humidity, strain and current measurement in gas or liquid environments are reviewed. Finally, we conclude with an outlook for challenges and opportunities of microfiber optical sensors.

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Etched multimode microfiber knot-type loop interferometer refractive index sensor

Cited by 19 publications

References 26 publications

Microfiber Knot Resonators: Structure, Spectral Properties, and Sensing Applications

Microfiber Knot Resonators: Structure, Spectral Properties, and Sensing Applications

Micro/Nanofibre Optical Sensors: Challenges and Prospects

Microfiber Optical Sensors: A Review

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