• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.287.1-287.1
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• 2016

Three-dimensional (3-D) semiconductor nanoarchitectures, including nano- and micro- rods, pyramids, and disks, are emerging as one of the most promising elements for future optoelectronic devices. Since these 3-D semiconductor nanoarchitectures have many interesting unconventional properties, including the use of large light-emitting surface area and semipolar/nonpolar nano- or micro-facets, numerous studies reported on novel device applications of these 3-D nanoarchitectures. In particular, 3-D nanoarchitecture devices can have noticeably different current spreading characteristics compared with conventional thin film devices, due to their elaborate 3-D geometry. Utilizing this feature in a highly controlled manner, color-tunable light-emitting diodes (LEDs) were demonstrated by controlling the spatial distribution of current density over the multifaceted GaN LEDs. Meanwhile, for the fabrication of high brightness, single color emitting LEDs or laser diodes, uniform and high density of electrical current must be injected into the entire active layers of the nanoarchitecture devices. Here, we report on a new device structure to inject uniform and high density of electrical current through the 3-D semiconductor nanoarchitecture LEDs using metal core inside microtube LEDs. In this work, we report the fabrications and characteristics of metal-cored coaxial $GaN/In_xGa_{1-x}N$ microtube LEDs. For the fabrication of metal-cored microtube LEDs, $GaN/In_xGa_{1-x}N/ZnO$ coaxial microtube LED arrays grown on an n-GaN/c-Al2O3 substrate were lifted-off from the substrate by wet chemical etching of sacrificial ZnO microtubes and $SiO_2$ layer. The chemically lifted-off layer of LEDs were then stamped upside down on another supporting substrates. Subsequently, Ti/Au and indium tin oxide were deposited on the inner shells of microtubes, forming n-type electrodes of the metal-cored LEDs. The device characteristics were investigated measuring electroluminescence and current-voltage characteristic curves and analyzed by computational modeling of current spreading characteristics.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.26-38
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• 1994

We demonstrate a repeatless transmission of 2.5 Gbps digital signal over 98 km opticla filbers using optical transmitter and optcial receiver which are designed and implemented using commercially available devices. The optical transmitter is realized by using a distributed feedback(DFB) laser. Temperature of the laser is thermoelectrically stabilized and the output optical power is also stabilized by using negative feedback. The output power of the transmitter is 0 dBm. The optical receiver consists of an InGaAs avalanche photodiode, a preamplifier. an automatic gain control amplifier, and a clock/data regenerator. We find an optimum decision threshold that gives the best receiver sensitivity form the measured V curve. The best sensitivity is -35.5dBm( BER-1*10S010T, PRBS=2S023T -1 ) and the overload power is -9 dBm. Finally, we achieve error free optical transmission with 98 km optical fibers. The exinction ration penalty of 2 dB. the chromatic dispersion penalty of 1 dB, and the total power penalty of 3.0 dB are measured. These results satisfy CCITT recommendation.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.313-317
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• 2012

We have evaluated a 1.3 ${\mu}m$ vertical-cavity surface-emitting laser (VCSEL), whose bottom mirror and central active layer were grown by metal organic chemical vapor deposition (MOCVD) and whose top mirror was covered with a dielectric coating, for 10 Gb/s data transmission over single-mode fibers (SMFs). Successful demonstration of error-free transmission of the directly modulated VCSEL signals at data rate of 10 Gb/s over a 10 km-long SMF was achieved for operating temperatures from $20^{\circ}C$ to $60^{\circ}C$ up to bit-error-rate (BER) of $10^{-12}$. The DC bias current and modulation currents are only 7 mA and 6 mA, respectively. The results indicate that the VCSEL is a good low-power consuming optical signal source for 10 GBASE Ethernet applications under controlled environments.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.92-93
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• 2003

초고속 광전송 네트워크에 사용되는 광부품으로 단일 모드 광섬유와의 낮은 광 결합 손실을 가지는 레이저 다이오드 개발이 필수적이다. 이러한 레이저 다이오드의 요구되는 특성으로써 저가의 광부품 제작을 위해 thermoelectric cooler 없이 고온에서 안정된 동작을 하는 uncooled type에, 광 isolator 도움없이 광반사에 의한 광손실을 줄여야 한다. 이러한 요건을 충족시키기 위하여 선택적 영역 MOCVD성장을 이용한 InP／InGaAsP 계열의 SSC-LD(spot-size converter integrated LD)를 연구하여 왔다. (중략)

• The Korean Journal of Pain
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• v.3 no.2
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• pp.139-143
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• 1990

There are several methods for the treatment of herpetic neuralgia, but there is no method that results in complete remission. The laser has lately come into use to reduce several acute or chronic pains. Twenty six patients who suffered from herpetic neuralgia were treated with Ne-Ne and Ga Al AS lasers simultaneously 2 or 3 times per week. In order to determine the degree of pain relief, we used the visual analogue scale. The results were as follows. 1) Low level laser therapy (LLLT) was a non-invasive, simple method. 2) The improvement rate after 15 irrradiations of laser was 63%. 3) The Highest improvement rate (24%) was shown after one irradiation of laser. 4) Only one patient above age 60 (3.8%) developed postherpetic neuralgia. 5) There was no significant difference effects of LLLT between above and below the age of 60. 6) There was no complication during or after irradiation of laser.

• Journal of Life Science
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• v.16 no.1
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• pp.114-119
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• 2006

The purpose of this study was to determine effects of the Ga-As (Gallium-Arsenide) Dens-Bio laser on mechanically injured sciatic nerves of rats. The improvement of the injured rat sciatic nerve was evaluated by measuring of nerve conduction velocity and amplitude of compound muscle action potential. The sciatic nerves of forty male Sprague-Dawley rats were compressed with hemostatic forceps for 30 seconds. The experimental group was divided into 4 subgroups according to the duration of treatment. Lower power infrared laser irradiation was done transcutaneously to the injured sciatic nerve area, 3 minutes daily to each of four treatment groups for 1, 3, 5, and 7 weeks, respectively. Compound muscle action potential and nerve conduction velocity of sciatic nerve were obtained before nerve injury and at 1, 3, 5, and 7 weeks after injury. There were significant difference of the nerve conduction velocity and amplitudes of compound muscle action potential between the treatment group and non-treatment group at 1, 3, and 5 weeks after laser treatment. However, there were no differences found between the electrophysiologic parameters that were measured after 7 weeks in two groups. There was significant correlation between the increment of compound muscle action potential and nerve conduction velocity after time course according to laser treatment. In conclusion, the low power laser treatment had improved the sciatic nerve function, and therefore these results may provide the basic data to clarify the neurological recovery and treatment after incomplete peripheral nerve injury.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.185-188
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• 2003

본 논문에서는 공진기 길이 변화에 따른 V-자형 알루미늄갈륨비소-갈륨비소(AIGaAs-GaAs) 양자선 레이저의 서브밴드 에너지 천이에 대한 스펙트럼과 시간적 스위칭 특성을 조사하였다. $300{\mu}m$ 이하의 짧은 공진기 길이를 갖는 V-자형 양자선 레이저는 공진기 손실의 증가로 인하여 n=1에서 n=2 서브밴드(subband)로의 양자화 천이(불연속적인 파장 스위칭)가 발생하였고, 초단 광펄스를 생성하는 이득 스위칭방식을 이용하여 초고속 레이징 특성을 관찰하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.38-39
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• 2003

The GaAs semiconductor whispering gallery modes, produced in the peripheral Rayleigh band region of W／sub Rayleigh／ ＝ (${\Phi}$／2)( 1-n／sub eff／n), exhibit novel properties of ultralow thresholds open to nano-ampere regime associated with photonic quantum ring (PQR) production (Fig 1 (a)). The PQR phenomena are associated with a photonic field-driven phase transition of quantum well(QW)-to-quantum wire (QWR) and hence the photonic (non-de Broglie) quantum corral effects, on the Rayleigh cavity confined carriers in dynamic steady state, occur as schematically shown in Fig 1. (omitted)

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.2-3
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• 2001

Characteristics of two-dimensional slab photonic crystal lasers will be summarized. Room temperature c.w operation is demonstrated at 1.6 $\mu\textrm{m}$ by using InGaAsP slab-waveguide triangular photonic crystal on top of wet-oxidized aluminum oxide. Recently, 2-D PBG structures have attracted a great deal of attention due to their simplicity in fabrication and theoretical study as compared to the three-dimensional counterparts [1]. Air-guided 2-D slab PBG lasers were reported by Caltech group (2). However, this air-slab structure is mechanically fragile and thermally unforgiving. Therefore, a new structure that can remove this thermal limitation is dearly sought after for 2-D PBG laser to have practical meaning. In this talk, we report room-temperature continuous operation of 2-D photonic bandgap lasers that are thermally and mechanically stable.(omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.69-70
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• 2008

Micro resonators have been actively investigated for bio/chemical sensors and RF M/NEMS devices. Among various materials, SiC is a very promising material for micro/nano resonators since the ratio of its Young's modulus, E, to mass density, $\rho$, is significantly higher than other semiconductor materials, such as, Si and GaAs. Polycrystalline 3C-SiC cantilever with different lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and its fundamental resonance was measured by a laser vibrometer in air and vacuum at room temperature, respectively. For the cantilever with $100{\mu}m$ length, $10{\mu}m$width and $1.3{\mu}m$ thickness, the fundamental frequency appeared at 147.2 kHz.