• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.396-399
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• 2002

Using a bi-layer anti-reflection coating of $TiO_2$and $SiO_2,$ we have achieved a minimum facet reflectivity of $~10^{-5}$ and a band width of 27 nm for a reflectivity of $~10^{-4}$ or less for 1.3 $\mu\textrm{m}$ spot size converter integrated semiconductor lasers. This coating is applicable to external-cavity-tuned laser sources and semiconductor optical amplifiers.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.26-35
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• 2007

We characterized the properties of the fabricated filter with the total internal reflection mirror (TIR) in the rectangular ring resonator and very small multimode interference (MMI) couplers on an InP material platform for photonic integrated circuits. Coupling power in and out of a resonator is increased by using an optimum MMI length of 110 ${\mu}m$ and a width of 9 ${\mu}m$, respectively. The semiconductor optical amplifier with the length of 120 ${\mu}m$ is integrated in the resonator to compensate the loss of the internal waveguide and the TIR mirror. A free spectral range of approximately 2 nm (244 GHz) is observed with an on-off ratio of 13 dB. The curve fitting also yields the power coupled per pass as 42%. To reach critical coupling at this coupling level would require a round trip loss of about 2.4 dB.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.146-147
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• 2012

InP 기판위에 자발성장법으로 성장된 InAs 양자점은 $1.55{\mu}m$ 영역에서 발진하는 양자점 반도체 레이저 다이오드 및 광 증폭기를 제작할 수 있기 때문에 많은 관심을 받고 있다. 광통신 대역의 $1.55{\mu}m$ 반도체 레이저 다이오드 및 광 증폭기 분야에서 InAs/InP 양자점이 많은 관심을 받고 있으나, InAs/GaAs 양자점에 비해 제작이 어려운 단점을 가지고 있다. InAs/InP 양자점은 InAs/GaAs 양자점에 비해 격자 불일치가 작아 양자점의 크기가 크고 특히 As 계 박막과 P 계박막의 계면에서 V 족 원소 교환 반응으로 계면 특성 저하가 발생하여 성장이 까다롭다. As 과 P 간의 교환반응은 성장온도와 V/III 에 의해 크게 영향을 받는 것으로 보고되었다. 그러나, P계 InGaAsP 박막 위에 InAs 성장 시 발생하는 As/P 교환반응에 대한 연구는 매우 적다. 본 연구에서는 InGaAsP 박막 위에 InAs 양자점 성장 시 GI (growth interruption)에 의한 As/P 교환반응이 InAs 양자점의 형상 및 광학적 특성에 미치는 영향을 연구하였다. 시료는 수직형 저압 Metal Organic Chemical Vapor Deposition (MOCVD)를 이용하여 $520^{\circ}C$의 온도에서 성장하였다. 그림1(a) 구조의 양자점은 InP (100) 기판위에 InP buffer layer를 성장한 후 InP와 격자상수가 일치하는 $1.1{\mu}m$ 파장의 InGaAsP barrier를 50 nm 성장하였다. 그 후 As 분위기 하에서 다양한 GI 시간을 주었고 그 위에 InAs 양자점을 성장하였다. 양자점 성장 후 InGaAsP barrier를 50 nm, InP capping layer를 50 nm 성장하였다. AFM측정을 위해 InP capping layer 위에 동일한 GI 조건의 InAs/InGaAsP 양자점을 성장하였고 양자점 성장 후 As분위기 하에 온도를 내려주었다. 그림1(b) 구조의 양자점은 그림1(a) 와 모든 조건은 동일하나 InAs 양자점과 InGaAsP barrier 사이에 GaAs 2ML를 삽입한 구조이다. 양자점 형상 특성 평가는 Atomic force microscopy를 이용하였으며, 광특성 분석은 Photoluminescence를 이용하였다.

• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.507-511
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• 1999

A 10 GHz timing extracted signal which is phase-locked to a 10 Gbit/s mode-locked optical fiber laser pulse train is obtained using a tour-wave-mixing signal in semiconductor optical amplifier. The phase-locked loop wm, demonstrated ~Llccessful1y over 8 hours and found to have the lock-in frequency range of 30 KHz. 0 KHz.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.282-283
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• 2000

본 연구에서는 사용한 양자 우물 구조는 그림 1과 같이 각 양자 우물의 두께가 다르게 분포되어 있다. 이러한 불균일 양자 우물 구조는 주로 광대역폭 반도체 광 증폭기를 위한 구조,$^{l).2)}$ 광대역폭 superluminescent diodes에 적용하기 위한 구조,$^{3)}$ 광대역폭 및 온도 비의존성 면발광 레이저를 위한 구조로 이용되고 있다.$^{4)}$ 이들 소자의 실현을 위해 우선 불균일 양자 우물 구조의 특성을 알아볼 필요가 있다. 따라서 본 연구에서는 이 구조를 CBE로 성장하고 릿지형 반도체 레이저를 제작하여 광학적 특성을 조사하였다. (중략)

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.353-354
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• 2008

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.37-42
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• 2000

We have numerically solved rate-equations of semiconductor optical amplifier (SOA) to understand the characteristics of SOA. The rate-equations we have used can describe injection carrier density, amplified spontaneous emission and signal photon density in spatial and time domain by dividing the cavity into multi-section. We have investigated injection carrier density, amplified spontaneous emission and signal photon density as a function of position and time in the case of single channel input in the form of square pulse. Also we have analyzed the non-linear phenomena of SOA in the case of injecting multi-channel wavelengths as in WDM. Intermodulation distortion (IMD) caused by beat among channels has significant effects on the signal distortion as the channel spacing becomes narrower, and channel crosstalk becomes larger as the power of signals increases. In the case of the injection of another CW laser whose wavelength is far enough from the signal wavelengths, the crosstalk and the output signal distortion can be significantly reduced. duced.

• Korean Journal of Optics and Photonics
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• v.34 no.4
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• pp.151-156
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• 2023

We propose to implement cost-effectively a high-speed short-haul interconnect by transmitting a 200-Gb/s/λ two-channel optical time-division-multiplexed signal generated by a carrier-suppressed optical pulse, which improves the robustness of the multiplexed signal to chromatic dispersion. The multiplexed 200-Gb/s signal is generated in the transmitter by combining two 100-Gb/s 4-level pulse-amplitude-modulated signals (generated using the optical pulse and two Mach-Zehnder modulators). After the signal is transmitted over a fiber, it is amplified by a semiconductor optical amplifier and detected by a photodiode. The amplified spontaneous emission noise is eliminated by an optical band-pass filter. The transmitted signal is reconstructed by a 2 × 2 multiple-input multiple-output equalizer, which compensates for crosstalk. Due to the use of the carrier-suppressed optical pulse, the 200-Gb/s signal can be transmitted over fiber with a chromatic dispersion of 40 ps/nm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.2
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• pp.46-54
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• 2007

We have fabricated and characterized MMI (Multimode Interference) coupled ring resonator with the total internal reflection mirrors and the semiconductor optical amplifier for the integration of the WDM (Wavelength Division Multiplexing) system. The TIR (Total Internal Reflection) mirrors were fabricated by self-aligned process and had losses of about 0.71 dB per mirror. Coupling in and out of a resonator was achieved using the extremely small MMI couplers. The MMI length and width used in the experiment were $119{\mu}m$ and $9{\mu}m$, respectively. The resulting FSR (Free Spectral Range) and on-off ratio were approximately 1.333 nm (162 GHz) and 13 dB, respectively.

• Korean Journal of Optics and Photonics
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• v.10 no.1
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• pp.58-63
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• 1999

A 10 GHz harmonically mode-locked semiconductor-fiber ring laser was implemented using a semiconductor optical amplifier at $1.5\mu\textrm{m}$ The laser pulse has 13~18 ps pulse duration, 0.4~0.6 nm spectral width and was positively chirped. The output pulse with an average power of 4 dBm was compressed to 6.8 ps using 2 km long standard single mode optical fiber.