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.
Group Refractive Index Measurement of Liquids Using Common-Path Swept Source Optical Coherence TomographyPublished: 01 August 2015 by American Scientific Publishers in Sensor Letters
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
Plastic optical fiber level measurement sensor based on in-line side holes is investigated theoretically and experimentally. The sensor consists of a plastic optical fiber with in-line side holes spaced about 5 cm apart. The 0.9 diameter in-line side holes were fabricated by micro-drilling. An analytical expression of the sensor transmittance was obtained using a simple ray optics approach. The measurements of the sensor transmittance were performed with a 55 cm height Mass cylinder. Both results show that the sensor transmittance increases as the number of side holes filled with water increases. The research results indicate that the plastic optical fiber based on in-line side holes can be used for water level measurement.
An in-line submillimeter hole fabricated by micro-drilling plastic optical fiber (POF) directly has been proposed as a compact refractive index sensor. Since the hole behaves as a concave lens if it is filled with a liquid having lower refractive index than that of the fiber core, transmittance increases in proportion to the refractive index. Analysis of the sensor transmittance has been performed using a simple ray optics model. Through immersing a 1.5-mm POF with a 0.35-mm-radius hole into various liquids, transmittance of the sensor has been measured at 670 nm. It has been shown that the experimental and analytical results are in excellent agreement.
Fabrication and Mode Coupling of Long-Period Fiber Grating by Winding a Wire Around an Optical Fiber Fixed to a Cylindri...Published: 15 May 2013 by IntechOpen in Current Trends in Short- and Long-period Fiber Gratings
Characteristics of jitter have been investigated in a 10‐GHz analog optical link using a quadrature‐biased Mach–Zehnder modulator followed by an erbium‐doped fiber amplifier (EDFA) and a PIN photodiode. For the case of low optical input power, jitter varies inversely with input power, indicating the thermal noise limited characteristic. For high input optical power, jitter saturates at a minimum for different RF power levels for the configuration without EDFA. For the configuration using EDFA, jitter is also inversely proportional to EDFA gain but shows different minima for different input optical power with output power fixed by adjusting EDFA gain because of amplified spontaneous noise noise. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2725–2727, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27196
Easy fabrication of long-period fiber grating by winding a wire around an optical fiber fixed to cylindrical RODPublished: 16 May 2012 by Wiley in Microwave and Optical Technology Letters
A new approach is presented for the easy fabrication of wire‐winding long‐period fiber grating based on the periodic winding of a wire around an optical fiber attached to a cylindrical rod. The periodic pressure of the wire induces change of the refractive index of the optical fiber core, and so the resonance wavelengths of the grating can be easily controlled according to the winding‐wire pitch controlled by a microprocessor. At the winding‐wire pitch of 500 μm, the spectra show resonance–wavelength dips corresponding to the LP02, LP03, LP04, and LP05 cladding modes; the resonance wavelengths go to longer wavelengths at the increased winding pitch of 510 μm; these are in good agreement with theoretical values. The polarization dependence of a resonance wavelength shift of 9 nm and transmission power difference of 2.5 dB was shown at the 520 μm grating pitch. When the diameter of the cylindrical metal rod was smaller, or higher tension by the winding pressure was applied, stronger mode coupling resulted in deeper dips in the transmission spectra according to induced higher index variation. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1937–1941, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26951
This article presents the experimental characterization of a mechanically induced long‐period fiber grating (MLPFG) array sensor for measuring the amplitude and width of an applied weight as well as detecting its position. The MLPFG array sensor consists of an optical fiber placed between a rubber cover and a 45‐cm‐long metal bar with round grooves on its upper surface divided into 10 different grating periods. The grating periods are sequentially increased by 10 μm from 690 to 780 μm, and the number of grooves per grating period is 60. Experimental results show that the MLPFG array sensor can be used for measuring the amplitude of an applied weight from the optical attenuation at the resonance wavelength, measuring the loading width from the full width at half maximum of the dip, and detecting the position of the applied weight from the resonance wavelength. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2295–2298, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26289
An optical fiber arterial pulse wave sensor is proposed using an in‐line Michelson interferometer that is a hollow optical fiber spliced to a single‐mode fiber at one end and cleaved at the other end. The proposed optical fiber arterial pulse wave sensor consists of an in‐line Michelson interferometer and steel reinforcement enclosed in a heat‐shrinkable tube. The sensor was directly attached onto a wrist and signals corresponding to arterial pulse waves successfully obtained. The signal‐to‐noise ratio of the sensor signals was better than 20 dB. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1318–1321, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25200
A fiber‐optic interferometric voltage sensor with a high‐sensitivity is investigated. The fiber‐optic voltage sensor is composed of an in‐line Michelson interferometer bonded to a piezoelectric transducer (PZT). The in‐line Michelson interferometer is a hollow optical fiber spliced to a single‐mode fiber at one end and cleaved at the other end. A phase shift in the sensor output signal is induced when applying an AC voltage to the PZT; and a higher‐amplitude voltage produces an output interference signal with a higher frequency. The relation between the amplitude of the applied voltage and the phase shift of the sensor output signal is found to be approximately linear and the slope of the relation graph is about 0.116 πradian/V. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1689–1691, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24434
Mode Analysis of a Tunable Side-Polished Optical Fiber Filter by a Polymer-Dispersed Liquid Crystal Based on Coupled-Mod...Published: 14 July 2007 by Korean Physical Society in Journal of the Korean Physical Society
A reflection-type side-polished optical fiber submersion sensor with an optical fiber mirror in a manhole is proposed. When this sensor is submerged into distilled water in a manhole and the measurement is made at about 1km from the sensor, the throughput power gain is changed by about 2.04dB at 1540nm and the resonance wavelength shifts from 1540nm to 1541.6nm.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Reflective Side-Polished Optical Fiber Submersion Sensor Using an Optical Fiber Mirror for Remote SensingPublished: 01 January 2007 by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Photonics Technology Letters
A reflection-type side-polished optical fiber submersion sensor (RSS) with an optical fiber mirror for remote sensing is proposed. When compared with a conventional transmission-type side-polished optical fiber submersion sensor (TSS), the RSS with an optical fiber mirror provides an improved response, and allows efficient remote submersion sensing. In experiments, the RSS with an optical fiber mirror detected submersion with 1 dB increased throughput power gain when compared with a conventional TSS, and provided efficient remote sensing at a distance of 1 km based on the resonance wavelength shift and transmission power gain
Fabrication of Fiber Device with Long-Period Fiber Gratings at Locations under Applied Pressure and Its Application as L...Published: 08 March 2006 by Japan Society of Applied Physics in Japanese Journal of Applied Physics
A bending-sensitive fiber (BSF) is fabricated and analyzed to create a microbend fiber sensor (MFS) with a simple structure. The BSF exhibits a gradual rather than sudden change in the microbend loss, according to a variation in the microbend applied to the BSF. According to the measured refractive index profile of the fabricated BSF, the proposed BSF consists of three different regions: the first core equal to the core of a SMF; the second core that is located around the first core, and whose refractive index is lower than the first core and higher than the cladding; and the cladding. The 3-D finite difference beam propagation method (3-D FD-BPM) is utilized to analyze the characteristics of the BSF. Based on the numerical results using 3-D FD-BPM and the fabricated BSF, a simple MFS with a BSF is created and compared to the MFS with a SMF. In particular, the MFS with the BSF showed a microbend loss from −1 to −20dB at 1550nm when the pressure given to the optical fiber is varied from 0 to 0.05MPa; meanwhile, the MFS with the SMF showed no optical power attenuation.
Jaehee Park participated at conference 4th International Symposium on Sensor Science.