• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.4
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• pp.72-75
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• 1985

1.3$\mu$m double-heterostructure GaInAsP/InP wafers have been grown by LPE and broad contact laser diodes have been fabricated. Electrical and optical characteristics of these lasers under pulsed lasing operation at room temperature are described. Typical threshold currents are below 2 Amp. corresponding to threshold current densities of 3 - 6 KAmp./$\textrm{cm}^2$ and peak lasing wavelength is shown to be at 1.315 $\mu$m.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.200-205
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• 1995

The 1st and 2nd-order grating structure for long wavelength DFB(Distributed FeedBack) laser diodes are successfully fabricated on InP substrates by using electron beam lithography and reactive ion etch techniques, and also characterized non-destructively by diffraction analysis without removal of photo-resis layer. A new composite layer made by lifted-off Cr layer on thin SiO2 film is developed and used as an etch mask, because PMMA, the e-beamresist, is unsuitable for reactive ion etch of InP. In addition, it is experimentally confiremed that diffraction analysis makes it possible to predict the grating parameters, and the analysis can be used as a non-destructive on-line test to prevent incomplete gratings from being successively processed.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.121-121
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• 1999

Gallium nitride (GaN) semiconductor is intensively under investigation for commercialization of short wavelength light emitting devices and laser diodes. One of serious obstacles to overcome is to reduce the defect density in GaN film grown by various techniques such as MOCVD, HVPE, etc. Many research groups including SAIT are trying to improve the defect density to 106-107/cm2 from the level of 108-1010/cm2. We have investigated epitaxial growth behaviour of GaN thin and thick films under hidride vapour phase epitaxy (HVPE) condition. In this report, we present the microstructural and crystallographical characteristics of the GaN films grown on sapphire (0001) substrate which were studied by both conventional and high-resolution transmission electron microscopy (TEM). Also we present some microscopic analysis results obtained from GaN films grown by ELO(dpitzsial lateral overgrowth)-HVPE and from GaN quantum well structures grown by MOCVD. Another serious problem in growing GaN thick film by HVPE is internal micro-cracks. We also comment the origin of the micro-crack.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.811-816
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• 2011

We develop a plastic object lens for blu-ray disc playing pick-up module as morethan 0.85 numerical aperture in this research. We design plastic object lens for blu-ray disc playing pick-up module's each factor's in balanced and made our designed lens by injection molding. Furthermore, by correction designing in mold-core, we optimization our lens efficiency as world grade; wave front aberration $0.028{\lambda}$. RMS, light axis differential 0.3967arcmin. We can manufacture localized blu-ray disc's pick-up lens's component and by this fact we obtain international competitiveness. The result of this research will be very helpful to develop a single objective lens for 3 different wavelength of laser diodes in playing and recording pick-up module.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.73-78
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• 2003

The InP thin films grown by metalorganic chemical vapor deposition (MOCVD) are widely used to optoelectronic devices such as laser diodes, wave-guides and optical modulators. Effects of various parameters controlling film growth rate such as gas-phase reaction rate constant, surface reaction rate constant and mass diffusivity are numerically investigated. Results show that at the upstream region where film growth rate increases with the flow direction, diffusion including thermal diffusion plays an important role. At the downstream region where the growth rate decreases with flow direction, film deposition mechanism is revealed as a mass-transport limited. Mass transport characteristics are also studied using systematic analyses.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.93-96
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• 2007

We demonstrate a 240 km reach DWDM-PON at 8-Gb/s capacity based on wavelength-locked Fabry-Perot laser diodes and a bidirectional EDFA. We achieve a packet-error-free transmission in both the 64 upstream and 64 downstream channels, guaranteeing a 125 Mb/s symmetric data rate per user. There is no noticeable dispersion penalty. The power penalty due to the crosstalk induced by the DWDM transmission and detuning between AWGs is less than 1.2 dB, when the detuning is within ${\pm}0.12 nm$.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.166-169
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• 2005

고속 데이터 전송을 함에 있어서 레이저 다이오드(LD)를 이용한 광접속 시스템은 최근 중요한 화두가 되고 있다. LD에 의하여 변조된 광신호는 광자와 캐리어의 동역학적 특성에 영향을 받으며, 이와 같은 LD의 동작 특성을 위해하기 위해서는 율방정식(Rate Equation)을 분석해야만 한다. 본 논문에서는 유한차분법(FDM)을 이용하여 율방정식을 분석하기 위한 모델을 제시하였으며, 이때 주입되는 전류부분에 디지털 혹은 아날로그 신호를 인가함으로써, 광접속 시스템에서 LD의 대역폭, SFDR (Spurious Free Dynamic Rage) 그리고 비선형 특성을 분석하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.94-95
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• 2003

최근 들어 저가용 광통신 소자를 제조하기 위한 방법으로 TEC를 사용하지 않는 비냉각형(uncooled) 레이저에 관한 연구가 활발히 진행되고 있다. 이를 위해 반도체 레이저를 형성하는 화합물 반도체 재료 적인 측면에서는 기존에 널리 사용되는 InGaAsP계 물질에 비해 AlGaInAs계 물질구조는 큰 conduction band offset ($\Delta$Ec=$\Delta$O.72Eg) 등으로 인해 고온에서 전자의 overflow를 억제하고 균일한 hole injection으로 인해 우수한 고온특성과 높은 이득(gain)을 보이는 장점을 지니고 있다. (중략)

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.371-376
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• 2007

We have investigated the lasing characteristics of the InGaAs quantum dot laser diode (QD-LD) and InGaAs quantum well laser diode (QW-LD) operated at the 980 nm wavelength range. The 980-nm lasers are used as a pumping source for a erbium-doped fiber amplifier (EDFA) and it shows high efficiency in long-haul optical fiber network. We have compared the threshold current density, the characteristic temperature, the optical power and the internal efficiency of QD-LD and QW-LD under a pulsed current condition. The QD-LD shows superior performances to the QW-LD. Further optimization of a LD structure is expected to the superior performances of a QD-LD.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.669-673
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• 2003

We fabricated a buried-ridge waveguide laser diode (B-RWG LD) which has more advantages for obtaining lateral single mode operation on the same ridge width and for the planarization of the device surface, compared to the conventional RWG LD. In this LD, the difference of the lateral effective refractive index can be controlled by the thickness of the InGaAsP layer which is grown on the active and the p-InP layers. The InGaAsP multiple quantum well was grown on a n-InP substrate by the CBE. The buried ridge structure was formed by selective wet etchings, followed by liquid phase epitaxy methods. The fabricated LD with the ridge width of 7 ${\mu}{\textrm}{m}$ showed a linear increase of the optical power up to 20 ㎽ without any kinks and a saturated output power of more than 80 ㎽. By measuring the far field pattern, we demonstrate that LDs with the ridge widths of 5 ${\mu}{\textrm}{m}$ and 7 ${\mu}{\textrm}{m}$ were operated in a lateral single mode up to 2.7I$_{th}$ and 2.4I$_{th}$, respectively.ely.