Plastic Optical Fiber Refractive Index Sensor Employing an In-Line Submillimeter Hole

Shin, Jong‐Dug; Park, Jaehee

doi:10.1109/lpt.2013.2278973

Cited by 39 publications

(30 citation statements)

References 10 publications

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“…Refractive index (RI) sensors are very important for monitoring water quality in either industrial applications or environmental control [1,2]. Many RI sensor configurations using optical fibers technology have been studied in the last years such as multimode tapered fibers [3], fiber-taper seeded long period grating (LPG) pair [4], multimode interference (MMI) devices [5], structures based in core diameter mismatches [6], Michelson interferometer using abrupt taper [7], core offset attenuators [8], in-line Mach-Zehnder interferometer setup by concatenating two singlemode fiber (SMF) tapers [9], and MMI based tapered fiber [10]. Most of those sensor configurations offer high sensitivity for RI close to 1.45 (RI of the fiber cladding), but present a relatively low sensitivity for RI close to distilled water ($1.333), a range of interest for many chemical and biosensing applications.…”

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High‐sensitivity refractive index sensors based on in‐line holes in plastic optical fiber

Shin

Park

2015

Micro & Optical Tech Letters

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In this letter, we propose a compact and simple high‐sensitivity refractive index sensor based on cascaded in‐line holes in multimode plastic optical fiber (POF). Due to multimode nature of the structure, transmittance of a sensor with N in‐line holes becomes the N‐th power of that for a single hole sensor to achieve high sensitivity easily. Experimental results show that a sensor with three 0.7‐mm holes spaced 5‐mm in 1.5‐mm POF exhibited a sensitivity of 43.8 dB/RIU, which is about three times in logarithmic scale that of a 0.7‐mm single‐hole sensor, 14.8 dB/RIU. Similarly, a sensor with three 0.9‐mm holes showed a sensitivity of 62.9 dB/RIU compared to 22.0 dB/RIU for a 0.9‐mm single‐hole sensor. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:918–921, 2015

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High‐sensitivity refractive index sensors based on in‐line holes in plastic optical fiber

Shin

Park

2015

Micro & Optical Tech Letters

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“…When fabricating the POF respiration sensor, multiple in-fiber microholes were first created in the central part of the POF using an inexpensive drilling machine. [15][16][17] Next, the waist-band was created by stitching elastic fabric to each side of an inelastic fabric centerpiece. The central part of the POF was then embedded in the inelastic fabric, while the remaining parts were merged into the elastic fabric on each side.…”

Section: Sensor Fabrication and Experimental Resultsmentioning

confidence: 99%

“…Figure shows a schematic diagram of a POF with a single in‐fiber microhole. When the POF is unbent (Figure A), the transmittance of the POF with a single hole is given as

normalT = \frac{false[{cos}^{- 1} ((), \frac{n_{2}}{n_{1}}) - {sin}^{- 1} ((), \frac{r_{h}}{L}) + {tan}^{- 1} ((), \frac{r_{h} sin θ_{h, max}}{L - r_{h} cos θ_{h, max}})}{{cos}^{- 1} ((), \frac{n_{2}}{n_{1}})},

where n 1 and n 2 are the core and cladding refractive indices, respectively, r h is the hole radius,

θ_{c} false(= {sin}^{- 1} \frac{n_{2}}{n_{1}}

) is the critical angle, L = atan θ c , and θ h , max is the maximum angle between the fiber axis and the point where the traversing ray reaches the microhole. Thus, if the POF has N in‐fiber microholes along its axis, the transmittance becomes T N = T N .…”

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Plastic optical fiber respiration sensor based on in‐fiber microholes

Ahn

Park

Shin

et al. 2018

Micro & Optical Tech Letters

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This paper presents a novel respiration sensor based on multiple in‐fiber microholes drilled along a plastic optical fiber (POF) that is stitched to a waist‐band wrapped around the patient's abdomen. The bending loss of a POF with a single microhole is analyzed in order to enhance the sensor sensitivity. Several sensors were fabricated using a 1.5 mm‐diameter POF with different numbers and spacing of 0.7 mm‐diameter microholes. The sensitivity of the respiration sensor increased when increasing the number and spacing of the microholes, where the POF respiration sensor with seven 0.7 mm‐diameter in‐fiber microholes spaced at 15 mm showed the highest sensitivity and sufficient strength for respiratory monitoring. Thus, the experimental results confirmed that a POF sensor based on in‐fiber microholes can be effectively used to monitor the respiration of patients.

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“…[16], [17]. Shin J, et al [18] and Xin G, et al [19] both reported a micro-hole based POF sensor, experimentally showing its feasibility for RI testing.…”

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Side-Hole Plastic Optical Fiber for Testing Liquid’s Refractive Index

et al. 2014

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A multimode plastic optical fiber with a sidehole fabricated by precision mechanical drilling technology is presented for refractive index (RI) sensing. A higher sensitivity of 1862.1 µW/RIU, when center wavelength of optical source is 652 nm and launched power is 1 mW, is obtained in a larger hole diameter of 350 µm, indicating that the larger hole diameter can increase the sensitivity of the sensor. Ray-optics method and finite-difference time-domain method are both utilized to theoretically evaluate the characteristics of the structure for RI testing, which is well in agreement with the experimental results. Energy field distribution is analyzed to explain the sensing mechanism of the structure, which demonstrates that the divergent effect of the side-hole like a negative lens is the key to sensing. Due to the advantages of relatively easy fabrication, low cost, and capable of continuous measurement, this side-holebased fiber sensing structure is attractive for RI monitoring in chemical, biological, and biochemical sensing region.Index Terms-Plastic optical fiber, refractive index sensing, side-hole structure.

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Plastic Optical Fiber Refractive Index Sensor Employing an In-Line Submillimeter Hole

Cited by 39 publications

References 10 publications

High‐sensitivity refractive index sensors based on in‐line holes in plastic optical fiber

High‐sensitivity refractive index sensors based on in‐line holes in plastic optical fiber

Plastic optical fiber respiration sensor based on in‐fiber microholes

Side-Hole Plastic Optical Fiber for Testing Liquid’s Refractive Index

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