• 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.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.28-33
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• 2004

An in-line fiber coupler, based on side-polished single-mode fibers covered with an intermediate coupling layer and a planar waveguide, is analyzed by modeling the interaction region as an equivalent multi-layered planar waveguide. The reflectance for the multi-layered structure with and without buffer layer is illustrated as a function of the refractive index and thickness of the overlay waveguides. When the refractive index of the overlay waveguides is greater than that of the fiber core, the conditions for the intermediate coupling layer to increase the power coupling from the fiber to the overlays is also explained. Through the experimental results using a LiNbO$_3$planar waveguide, we show that the theoretical analysis is reasonable and in good agreement with the measured values.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.2
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• pp.33-38
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• 2004

We have demonstrated a tunable Inter based on an asymmetric directional coupler made of a side-polished polarization maintaining fiber coupled with a polymer planar waveguide. The thermo-optic effects of the polymer planar waveguide induced by a micro-strip heater placed on the top layer of the device leads to shift of resonance wavelength of the coupler. The fabricated device exhibited wide tunable range exceeding 230 nm with 720 ㎽ of applied electrical power.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.134-139
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• 2002

We report an experimental investigation of the wavelength and polarization selectivity of a side-polished fiber in contact with a metal-clad planar waveguide. The influences of the structural parameters of the planar waveguide, including refractive index of the superstrate and metal thickness, on the optical transmission characteristics of the device were measured and explained. The conditions for high wavelength and polarization selectivity wore predicted and demonstrated experimentally.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.228-234
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• 2002

We report theoretical investigation on the polarization selective coupling characteristics of a side-polished fiber directional coupler with a thin metal interlayer. Based on normal mode theory the coupling properties of the device under various structural conditions are analyzed. It is shown that the coupling strength between TE modes weakens rapidly with increase or metal interlayer thickness, whereas that between TM modes becomes stronger. The design conditions of the polarization splitter using the coupler to achieve high extinction ratio and low insertion loss are presented.

• Proceedings of the Optical Society of Korea Conference
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• 2001.08a
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• pp.288-289
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• 2001

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.138-139
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• 2000

광섬유-평면도파로 결합기는 측면 연마된 광섬유와 그 위에 올려진 평면도파로 사이의 소산장 결합(evanescent field coupling)를 이용하는 소자이다. 이 결합기는 기본적으로 파장선택성과 편광선택성을 있고, 삽입손실이 매우 작고 기계적 신뢰성이 우수하여 많은 주목을 받아 왔다. 평면도파로의 재료로 반도체, 크리스탈, 액정크리스탈, 폴리머등 다양한 물질이 이용될 수 있어 광통신뿐만 아니라 광 센서 분야에서 활발하게 연구되어 왔다. (중략)

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.419-423
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• 1999

Optical filters utilizing the evanescent filed coupling between the side polished fiber and polymer planar waveguide were fabricated and optical properties of the devices were measured. A scheme for reducing polarization dependent properties of the device was proposed and demonstrated experimentally. Our measurement results showed that resonance wavelengths and filtering depth of the optical filters can be determined by adjusting thickness of planar waveguide and polishing depth of the fiber. The device fabrication procedure including fiber polishing steps and formation of polymer planar waveguide were described. The optical characteristics of fabricated optical filers were that 3 dB bandwidth was 15 nm, the resonance wavelength difference between the TE and TM polarized response was less then 2 nm, and insertion loss was less then 0.2 dB. The measured resonance wavelength drift dut to the variation of ambient temperature was -0.35 nm/$^{\circ}C$.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.100-101
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• 2000

편광기는 광변조기나 스위치 등과 같이 구동을 위해 하나의 편광성분을 요구하는 소자를 동작시킬 때 필수적으로 요구되는 소자이다. 편광기를 구현하는 기법에 따라 벌크형, 집적광학형 그리고 광섬유형으로 구분할 수 있다. 광섬유형은 광섬유를 절단하지 않고 제작이 가능하여 삽입손실이 작고 높은 기계적 신뢰성을 가진다. 측면 연마된 광섬유(side-polished fiber)위에 복굴절 크리스탈$^{(1)}$ , 액정크리스탈$^{(2)}$ , 금속막$^{(3)}$ , 그리고 복굴절을 가지는 평면도파로$^{(4)}$ 를 결합한 구조가 잘 알려져 있다. 특히 광섬유-평면도파로 결합 구조는 원하는 파장에서 TE혹은 TM 편광성분을 선택적으로 제거할 수 있고 평면도파로 물질선택이 용이한 구조이기 때문에 많은 주목을 받아 왔다. 하지만 지금 까지 알려진 광섬유-평면도파로 결합기를 이용한 편광기는 편광선택 작용이 발생하는 파장범위가 좁아 범용적으로 사용하는데 적합하지 않는 점이 있다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.190-191
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• 2005