• E2M - 전기 전자와 첨단 소재
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• 제9권3호
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• pp.240-245
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• 1996

Non-ozone layer destructive Chlorofluorocarbon(CFC) altematives(CHCIF$_{2}$ and $C_{2}$H$_{2}$F$_{4}$) have been initially used for laser-induced thenrmochemical etching of GaAs. High etching rate up to 188.mu.m/sec and an aspect ratio of 2.7 have been achieved by a single scan of laser beam, respectively. The etching rate at constant ambient gas pressure was found to saturate for beam power. The chemical compositions of the reaction products deposited on the etched groove were measured by Auger electron microscopy(AES). Etched profile, depth and width were observed by scanning electron microscope(SEM).

• 전자공학회논문지A
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• 제32A권1호
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• pp.119-128
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• 1995

We report hybrid and passive mode-locking results of tilted-stripe AlGaAs semiconductor laser traveling wave amplifiers with saturable absorbers. Dependence ofthe pulse width on the mode locking frequency, the bandwidth of spectral filters, and the bias current of the laser amplifier are investigated. We generate 4 ps optical pulses by using the hybrid mode locking technique. The repetition rate and the peak power of generated pulses are 516 MHz and 170 mW, respectively. The tuning range of uor mode locked laser is 10 nm with the center wavelength of 780 nm. We also generate 2.6 ps optical pulses with peak power of 830 mW by using the passive mode locking technique.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.169-171
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• 1989

The curved active layer inner stripe(CALIS) laser diode has been developed. The tight confinements of current and carrier result in low thershold current(20-30mA) with stable fundamental transverse mode operation up to the output power of 30mW CW.

• 한국진공학회지
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• 제15권3호
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• pp.280-286
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• 2006

디지털 합금 (digital-alloy) 성장방법을 사용한 AIGaAs층을 이용하여 $1.3{\mu}m$ vertical cavity surface emitting laser (VCSEL)에 사용될 수 있는 AlGaAs/GaAs distributed Bragg reflector (DBR)를 분자선 에피탁시 (molecular beam epitaxy) 방법을 통해 제작하였다. 3인치 1/4 크기의 기판에 디지털 합금 AlGaAs층을 사용한 DBR을 성장하고 기판 여러 부분에서의 반사율을 측정하여 각 부분 간의 반사율 편차가 0.35%이내임을 확인하였다. TEM 사진을 통한 계면분석을 통해 디지털 합금 AlGaAs층의 조성과 두께가 균일함을 확인하였는데, 이는 디지털 합금 AlGaAs층의 성장시 기판 표면의 온도가 불균일하더라도 크게 영향을 받지 않음을 보여준다. 이를 통해 DBR의 균일성에 따라 소자의 특성에 큰 영향을 받는 InAs 양자점을 활성층으로 사용하는 VCSEL의 수율을 향상시키는데 디지털 합금 AlGaAs층을 이용한 DBR이 응용될 수 있음을 보였다.

• 대한물리치료과학회지
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• 제9권2호
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• pp.99-109
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• 2002

We designed the experiments to elucidate the anti-inflammatory effect of low power laser stimulation on acupoint or non-acupoint using arthrogenic solution induced poly arthritis animal model. In order to achieve the experimental purpose, change in body weight paw edema, pathological changes in inflammed pint and the serum interlukin-6 level were measured after arthritis induction in acupoint later stimulated group, non acupoint laser stimulated group and non treated control animal. The results were summerized as follows: 1. The consistent increase in body weight was observed in the normal animal during whole experimental period, while the induction of arthritis significantly suppressed increase in body weight from the 15 day after arthritis induction. Especially, non treated animal group showed more suppressive effect on increase in body weight as compared to that of low power laser stimulated groups (P<0.05). 2. Low power laser stimulation on acupoint (Zusanli) significantly inhibited edema in the left side paw from the 12th day after arthritis induction as compared to that of non treated animals. This suppressive effect on paw edema was maintained until the end of experiment. 3. Laser treatment on acupoint dramatically suppressed the radiological change (i.e. new bone proliferation and soft tissue swelling) caused by arthritis as compared to that of non treated group animals. 4. Low power laser treatment reduced the increase in serum interlukin-6 caused by arthritis induction to levels observed in the normal animals. In conclusion, the results of the present study demonstrated that low power laser stimulation on acupoint has potent anti-inflammatory effect on arthritis. Thus it is recommended that low power laser be used for long term treatment of arthritis induced inflammation. However, further study is necessary to clarify the possible side effect of laser treatment depending upon intensity and duration of stimulation.

• International Journal of Contents
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• 제7권2호
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• pp.59-63
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• 2011

The aim of our study was to evaluate the immediate effects of an 830-nm Aluminium gallium arsenide (GaAlAs) laser, by examining the changes, in pressure-pain threshold (PPT) and tenderness at 3 kg of the myofascial trigger point (MTrP) of the upper trapezius muscle in visual display terminal (VDT) workers in comparison with placebo treatment. Thirty VDT workers (13 males, 17 females) with complaints of upper trapezius muscle were recruited. All participants were given either active GaAlAs laser (830 nm wavelength, 450 mW, 9 J at point) or placebo GaAlAs laser, according to the double-blinded and placebo-controlled trial. Both active and placebo low-level laser therapy (LLLT) treatments showed no significant effect on PPT and tenderness at 3 kg. These results suggest that a higher dosage may be necessary to produce immediate effects when applying LLLT to the MTrP of relatively large muscles such as the upper trapezius muscle.

• Journal of Oral Medicine and Pain
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• 제36권4호
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• pp.215-224
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• 2011

본 연구의 목적은 과민치아에 904 nm GaAs 다이오드 레이저를 조사하여 치료효과를 연구하여 과민 치아의 치료에 이러한 저수준 레이저 요법을 임상적으로 사용할 수 있는지 가능성을 파악하는 데 있다. 단국대학교 치과대학 부속치과병원 안면 동통 구강내과에 내원한 환자를 대상으로 하였으며, 각 환자는 치경부에 사아질이 노출된 치아가 적어도 좌우로 2개 이상의 짝이 되는 치아를 소유하였다. 본 연구에 사용된 치아는 모두 50 개로써 실험군 25개, 대조군 25 이었다. Tactile test, cold(ice stick) test, electrical pulp test 를 실험전, 실험 1주후, 2주후, 3주후, 4주후 모두 5회 시행하였다. 레이저조사는 첫방문시, 1주후, 2주후, 3주후 등 4회하되 모두 세가지 검사를 마친 후 시행하였다. 전기치수 검사 외 Tactile test와 cold test는 주관적 평가인 visual analogue scale을 사용하였다. 실험 결과, Tactile test에서 VAS 수치는 시간 경과에 따라 유의하게 감소하였으나 실험군과 대조군간에는 유의한 차이가 없었다. 전기치수 검사에서는 실험군의 과민도가 대조군에 비해 유의하게 높았으나 (높은 역치를 의미) 시간 경과시 유의한 변화는 볼 수 없었다. 온도 (cold) 검사에서는 레이저 조사후 실험군과 대조군 간의 차이뿐 만 아니라 시간 경과 시에도 유의하게 감소하였다. 이러한 결과를 보아 904 nm GaAs 레이저는 과민치아의 치료에 비가역적인 방법으로서 효과적으로 사용할 수 있으리라 사료된다.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1242-1247
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• 2003

In order to passivate the GaAs surface, silicon-nitride films were fabricated by using laser CVD method. SiH$_4$ and NH$_3$ were used to obtain SiN films in the range of 100∼300$^{\circ}C$ on p-type (100) GaAs substrate. To determine interface characteristics of the metal-insulator-GaAs structure, electrical measurements were performed such as C-V curves and deep level transient spectroscopy (DLTS). The results show that the hysteresis was reduced and interface trap density was lowered to 1,012 ∼ 1,013 at 100 ∼ 200$^{\circ}C$. According to the study of surface leakage current, the passivated CaAs has less leakage current compared to non-passivated substrate.

• 한국광학회:학술대회논문집
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• 한국광학회 1997년도 Advance Program of 14th optics andquantum Electronics conference, 1997제14 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.67-67
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• 1997

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1292-1301
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• 2006

This article investigates numerically the carrier-phonon interactions in thin gallium arsenide (GaAs) film structures irradiated by subpicosecond laser pulses to figure out the role of several recombination processes on the energy transport during laser pulses and to examine the effects of laser fluences and pulses on non-equilibrium energy transfer characteristics in thin film structures. The self-consistent hydrodynamic equations derived from the Boltzmann transport equations are established for carriers and two different types of phonons, i.e., acoustic phonons and longitudinal optical (LO) phonons. From the results, it is found that the two-peak structure of carrier temperatures depends mainly on the pulse durations, laser fluences, and nonradiative recombination processes, two different phonons are in nonequilibrium state within such lagging times, and this lagging effect can be neglected for longer pulses. Finally, at the initial stage of laser irradiation, SRH recombination rates increases sufficiently because the abrupt increase in carrier number density no longer permits Auger recombination to be activated. For thin GaAs film structures, it is thus seen that Auger recombination is negligible even at high temperature during laser irradiation.