• Korean Journal of Optics and Photonics
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• v.30 no.6
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• pp.249-254
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• 2019

An optical current sensor device that measures electric current by the principle of the Faraday effect was designed and fabricated. The polarization-rotated reflection interferometer and the quadrature phase interferometer were introduced so as to improve the operational stability. Complex structures containing diverse optical components were integrated in a polymeric optical integrated circuit and manufactured in a small size. This structure allows sensing operation without extra bias feedback control, and reduces the phase change due to environmental temperature changes and vibration. However, the Verdet constant, which determines the Faraday effect, still exhibits an inherent temperature dependence. In this work, we tried to eliminate the residual temperature dependence of the optical current sensor based on polarization-rotated reflection interferometry. By varying the length of the fiber-optic wave plate, which is one of the optical components of the interferometer, we could compensate for the temperature dependence of the Verdet constant. The proposed optical current sensor exhibited measurement errors maintained within 0.2% over a temperature range, from 25℃ to 85℃.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.547-554
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• 2004

We investigated a LiNbO$_3$ based integrated-optic polarization controller with the Ti-indiffused waveguide along the z-axis utilizing the electro-optic effect. The device consists of a first quarter-wave (λ / 4) followed by a half-wave (λ / 2) and a second quarter-wave (λ / 4) wave-plate. We analyzed the amount of phase change and the transformation of the polarized mode as a function of the combination of wave-plates and of their applied voltages. The operation has been systematically measured utilizing a polarimeter and Poincare sphere. We confirmed that the fabricated device controls the transformations from any arbitrary input state of polarization (SOP) into any general output SOP.

• Korean Journal of Optics and Photonics
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• v.11 no.6
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• pp.411-417
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• 2000

The waveguide structure effects of a spot-size converter (SSe) of a $1.3\mu{m}$ FP(Fabry-Perot)-LD(Laser Diode) were investigated. Its coupling efficiency and alignment tolerance with a single-mode fiber (SMF) were carefully examined by using a 3dimensional BPM (Beam Propagation Method). It was shown that the fOlmation of enough length of straightened waveguide around the end of the sse region can substantially improve the optical coupling efficiency for a vertically tapered sse. In contrast, a down-taper structure for a laterally tapered sse has superior characteristics to an up-tapered one. We suggested good sse structures which can provide a high coupling efficiency as well as a large alignment tolerance with an .SMF. .SMF.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.10-11
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• 2000

광통신을 이용한 근거리 전송과 장거리 전송에서 1.3 및 1.55 $mu extrm{m}$ 파장 영역의 빛이 사용되고 있다. 향후, 각 가정마다 광선로를 연결하는 Fiber-to-the-home (FTTH)의 개념과 광CATV가 발전함에 따라 1.3 및 1.55 $\mu\textrm{m}$ 빛을 검출하는 소자와 송신하는 소자가 필요하게 된다. 본 논문에서는 이러한 다중파장을 검출할 수 있는 집적소자를 제작 및 측정하였다. 본 논문에서 사용된 epitaxial layer의 구조는 N-InP 기판 위에 1 $\mu\textrm{m}$의 n-InP buffer층, 5층의InGaAs/InGaAsP 다중양자우물과 0.2 $\mu\textrm{m}$ InGaAsP separate confinement heterostructure (SCH) 층, 0.5$\mu\textrm{m}$ InP clad층과 0.1 $\mu\textrm{m}$ InGaAs cap 층으로 구성되어있다. 모든 epi 층은 InP 기판에 격자 정합이 되어있다. 다중양자우물구조는 84 $\AA$의 InGaAs 우물층과 100 $\AA$의 InGaAsP 장벽층으로 구성되며, 상온에서 0.787 eV (1.575 $\mu\textrm{m}$)의 bandgap energy를 갖도록 설계하였다. (중략)

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.333-339
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• 1994

We fabricated a single mode fiber pigtailed PIN-preamplifier front-end receiver module for the high speed optical receiver. Hybrid method was used to integrate GaInAs PIN photodiode and transimpedance type GaAs preamplifier. The capacitance and the diameter of light receiving area of PIN photodiode were 0.35 pF and $20{\mu}m$ respectively. The -3 dB cut-off frequency of PIN-preamplifier module was above 2 GHz, and the sensitivity of the module at 2.5 Gbps NRZ $(PRBS=2^{23}-1)$ signal was -25.2 dBm at $10^{-9}$ BER. > BER.

• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.294-300
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• 1993

Monolithic NOR and INVERTER active optical logic devices inte- grated with surface-emitting microlasers, heterojunction photo- transistors(HPT) in parallel and resistors in series are characterized. The differential quantum efficiency of the typical AlGaAs superlattice microlaser integrated in the active optical logic devices is 15%. Current gain of the HPT is 57, when emitter-collector voltage and input optical power are 4 V and $50{\mu}W$, respectively. $57{\mu}W$ of output power from the active optical logic device decreases to zero when $47{\mu}W$ of input optical power is incident on the HPT part of the active logic device.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.106-106
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• 2012

인체 내 소량의 생체성분을 감지하는 바이오센서 기술은 질병 진단뿐만 아니라 예방 및 관리로 의료서비스 확대 및 의료비 감소 효과를 가져올 수 있는 기술이다. 광 바이오센서는 광학적인 측정방법을 이용하여 다양한 생화학물질들의 상호 반응을 검출해 낼 수 있는 바이오센서로 현재 활발하게 연구가 진행되고 있다. 일반적으로 형광물질, 발색물질 등의 발광물질을 인식물질에 표지하여 인식물질과 분석물질과의 반응 유무를 표지된 발광물질의 광 신호를 감지하여 분석물질을 검출해내는 표지식 광 바이오센서 기술이 상용화되고 있다. 그러나 이러한 분석 방법은 민감도는 우수하지만 분석 시간이 매우 느리고, 고가의 분석 장비를 필요로 하는 단점들을 가지고 있다. 이러한 단점들을 극복하기 위하여 생화학 반응 유무를 표지물질 없이 광학적 방식으로 직접 측정해내는 비 표지식 광 바이오센서 기술이 최근 들어 많이 연구되고 있다. 본 논문에서는 비표지식이면서 분광기 없이 분석 가능한 공진 반사광 바이오센서 기술에 관한 내용을 소개하고자 한다. 공진 반사광 바이오센서는 광파장 이하의 주기를 가진 주기적 공진 격자 표면에서 일어나는 항원-항체 반응에 대한 공진 반사 파장을 측정하여 원하는 바이오물질을 고감도로 검출할 수 있는 바이오센서이다. 또한, 인체 내장을 위하여 플렉시블 기판 상에 GaN LED를 집적하여 전립선암 바이오 마커 검출에 대한 결과를 소개하고자 한다.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.489-492
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• 2006

We demonstrate a beat frequency-Switchable dual-mode external cavity laser hybrid integrated on planar lightwave circuit with an FP-LD and a sampled grating as external reflector. The dual-mode external avity laser was able to switch its beat frequency from 132GHz to 406GHz by changing LD current from 50mA to 55mA.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.198-202
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• 1992

Silver ion-exchanged glass waveguide with its large surface index difference and shallow depth is suitable to be used for the hybrid integration of semiconductor device and glass waveguide using the semiconductor film grafting technique. We report characteristics of the planar and channel glass waveguides exchanged in the diluted silver nitrate melt in the visible and infrared spectral region. Especially, we determined the fabrication parameters for single-mode channel waveguide at 1.5.$\mu$m, an important wavelength in the optical communication. Directional couplers with several different configurations were fabricated, and their 3 dB coupling length was determined as a function of wavelenGh and polarization.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.6
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• pp.17-32
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• 1982

Wave propagation in gyrotropic or anisotropic medium is analyzed in terms of the eigenmodes of the medium, which are admixture of TE and TM waves. The field composition and the phase velocity of the modes are also determined. The results of the analysis are applied to thin film optical waveguide using such medium as substrate and/or film. Based on the characteristic equations for phase constants of the waveguide, the condition for TE-TM mode convection is derived, and wave propagation in the guide is represented in the form of Jones matrix, which allows a new interpretation in the conversion efficiency of the thin-film optical waveguides.