• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.8
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• pp.513-517
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• 2015

We proposed and demonstrated a simultaneous measurement method to detect the refractive index and temperature of a medium using a side-polished fiber involving FBG (fiber Bragg grating). The temperature of a medium was obtained by using the Bragg wavelength shift of FBG, while the refractive index of medium were calculated by using the transmission loss. The Bragg wavelength is independent on the refractive index of the covering medium placed on surface of side-polished fiber, while the transmission loss at off-Bragg wavelength highly depends on the environmental temperature because of thermo-optic effect of the medium.

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.166-169
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• 2008

The submersion monitoring system based on a reflective side-polished optical fiber submersion sensor with an optical fiber mirror was shown to be an effective alarm system with remote monitoringwhen the drainage capacity of a common utility duct is exceeded due to heavy rainfall. The proposed sensor was connected to an existing installed optical fiber network at a height of 250mm in a common utility duct, and then tested under sample materials(distilled water, river water, sea water, foul water, muddy water, petroleum, edible oil) at a distance of 1km from the sensor for remote sensing. In experiments, the proposed real-time sensor system reduced maintenance cost and improved monitoring efficiency by using a reflection-type side-polished optical fiber submersion sensor efficient for remote monitoring of a common utility duct.

• Journal of Sensor Science and Technology
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• v.19 no.6
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• pp.428-434
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• 2010

In this study, a novel gas sensor based on evanescent field coupling between single mode side polished fiber and solvatochromic dye dispersed polymer waveguide was demonstrated. We fabricated a side polished optical fiber device as a volatile organic compounds gas detector. Solvatochromic dye was coated on the top of the side polished optical fiber to take advantage of evanescent field coupling. The solvatochromism can be defined as the phenomenon whereby a compound changes color, either by a change in the absorption or emission spectra of molecule, when reacted in different VOCs. The device reacted to polarity gases like a hexane, butane, xylene etc. The resonance wavelength was shifted by the xylene concentration which range was 0.1 ppm ~ 100 ppm. Also, the response with the concentration was lineer and the detection limit was 0.1 ppb.

• Journal of Sensor Science and Technology
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• v.32 no.1
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• pp.51-54
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• 2023

We investigated a humidity sensor based on a polyimide-coated side-polished optical fiber. The polyimide film absorbed moisture, causing the resonant wavelength of the sensor to shift to a longer wavelength owing to the changes in the optical properties of the film. The experimental results showed that the resonant wavelength of the device shifted by 17-18 nm when relative humidity changed from 30% to 90%.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.254-258
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• 2007

A novel cure sensor based on the side-polished single mode fiber has been proposed and demonstrated. Two different UV curable epoxies were used to verify the feasibility of the side-polished single mode fiber as a high sensitivity cure sensor. The volume change of the epoxy by UV curing results in a corresponding change of the refractive index. The sensor can be used to monitor the curing process, the refractive index variation and the volume change of epoxy in real time during the UV curing process. In addition, small birefringence of the epoxy film can be detected using the sensor.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.286-290
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• 2005

We have demonstrated a refractometer for liquid based on a side-polished fiber. The device consists of a side-polished single mode fiber and a rectangular space which plays a role of the multimode planar waveguide when it is infused with a liquid. We presented a simple method to acquire the refractive index of a liquid by use of the spacings of periodic resonance wavelengths of the device. The resolution of the fabricated refractometer was order of $10^{-5}$

• Journal of the Optical Society of Korea
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• v.7 no.3
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• pp.180-187
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• 2003

A theoretical presentation by using a three-dimensional finite difference beam propagating method (3-D FD-BPM) for the evanescent coupling is offered with respect to the refractive indexes between a side-polished optical fiber and an infinitely planar waveguide with a conductor cladding (PWGCC). The PWG is suspended at a constant distance from an unclad fiber core and attached with a perfect conductor (PEC) on one side. The coupling and propagation of light are found to depend on both the relationship between the refractive index values of two structures and the configuration of the side-polished fiber used in the PWGCC. The spreading of light in the unconfined direction of a PWGCC is presented with the distribution of electric fields in xy - plane and the absolute amplitude of electric fields along the x and y axis. The power of the light propagation in a fiber decreases exponentially along the fiber axis as it is transferred to the PWGCC, where it is carried away.

• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.337-341
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• 2010

A high sensitivity fiber optic temperature sensor based on a side-polished fiber (SPF) coupled to a tapered multimode overlay waveguide (MMOW) is proposed and studied. Both tapered and non-tapered MMOW were considered to study the effect of tapering of MMOW on the characteristics of the device and to investigate the criticality of the uniformity of the multimode overlay waveguide over the SPF. Present study shows that tapering of the MMOW can be used to tune the desired wavelength range without any loss in the sensitivity. Sensitivity up to 9 nm/$^{\circ}C$ within the temperature range of 25 to $100^{\circ}C$ can be achieved with the proposed sensor, almost 6 times higher compared even to state-of-the-art high-sensitivity grating-based fiber optic temperature sensors.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.651-657
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• 2003

We have demonstrated an in-line polarization splitter based on a side-polished fiber coupler including a thin metal intermediate layer. The experimental results revealed that the metal layer with proper thickness prevents TE polarization component from optical coupling between two contacted side-polished fibers, whereas it allows TM polarization component to the coupling. The design and fabrication techniques about the polarization splitter exploiting the side-polished fibers have been presented. The fabricated polarization splitter exhibited 18dB and 23dB of isolation ratio for TE polarization and TM polarization, respectively. The measured insertion loss for TE and TM polarization was 0.7dB and 1.3dB, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.57-62
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• 2004

We report the fiber-optic current sensors composed of a side-polished single-mode fiber with the thermo-optic Polymer layer and the metal wire as a heater. The index change of polymer layers caused by the resistant heat of the metal wires induces the optical attenuation through the evanescent field of the side-polished single-mode fiber. Two types of the sensors are proposed and their characteristics as a current sensor are investigated.