• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.207-207
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• 2010

Both ZnO and GaN have excellent physical properties in optoelectronic devices such as blue light emitting diode (LED), blue laser diode (LD), and ultra-violet (UV) detector. The ZnO/GaN heterostructure, which has a potential to achieve the cost efficient LED technology, has been fabricated by using radio frequency (RF) sputtering, pyrolysis, metal organic chemical vapor deposition (MOCVD), direct current (DC) arc plasmatron, and pulsed laser deposition (PLD) methods. Among them, the PLD system has a benefit to control the composition ratio of the grown film from the mixture target. A 500-nm-thick ZnO film was grown by PLD technique on c-plane GaN/sapphire substrates. The post annealing process was executed at some varied temperature between from $300^{\circ}C$ to $900^{\circ}C$. The morphology and crystal structural properties obtained by using atomic force microscope (AFM) and x-ray diffraction (XRD) showed that the crystal quality of ZnO thin films can be improved as increasing the annealing temperature. We will discuss the post-treatment effect on film quality (uniformity and reliability) of ZnO/GaN heterostructures.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.139-143
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• 1991

GRIN-SCH quantum well structured Laser Diode were fabricated using MOCVD and operated as CW at room temperature. The threshold current density of the LD with 670${\mu}{\textrm}{m}$ cavity length was 530 A/$\textrm{cm}^2$. For the ridge waveguide type index guiding structured LD with 6${\mu}{\textrm}{m}$ stripe width and 240${\mu}{\textrm}{m}$ cavity length, the threshold current was 50㎃. The maximum differential quantum efficiency was 0.95W/A when the optical output was 60mW. The lasing wavelength of QW LD was 865nm. In the L-I measurement. TE mode was superior to TM mode. From the near field pattern, single lateral mode operation was observed.

• The Korean Journal of Pain
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• v.14 no.1
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• pp.51-55
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• 2001

Background: Oral mucositis is a common complication of anticancer chemotherapy. The sequelae of this consist of an increased risk of infection, moderate to severe pain, compromised oral function, and bleeding. This study was performed to evaluated the effects of the He-Ne laser and the Ga-Al-As laser on oral mucositis caused by anticancer chemotherapy in pediatric patients. Methods: There were 3 cases of osteosarcoma and 6 cases of leukemia. All patients received He-Ne laser (632.8 nm wavelength, power 60 mW) application on 400-600 Hz scanning for 5-20 minutes and Ga-Al-As laser (904 nm wavelength, power 40 mW) application by fiberoptic hand piece placed in immediate proximity to the tissue without direct contact with it for 30 seconds per point for 5 days per week. During the application patients wore wavelength-specific dark glasses and were instructed to keep their eyes closed. Results: The mean number of treatments with oral intake was $4.89{\pm}0.64$. The mean number of total treatments was $9.44{\pm}2.59$. There were no significant side effects during and after the laser treatments. Conclusions: He-Ne laser and Ga-Al-As (IR) laser treatment were well tolerated and reduced the severity and duration of chemotherapy-induced oral mucositis in pediatric oncologic patients.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.2025-2031
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• 1989

In this paper, using optical effect of characteristics of GaAs compound, two potential application of optical controlled GaAs MESFET are demonstrated` detector, microwave amplifier gain control. These lead to the possibility of the interaction with optical devices. The preliminary experiments show the light induced voltage, the increase in the drain currnet and the change in the microwave scattering parameters of GaAs MESFET under optical illumination(He-Ne laser). And imcrowave amplifier gain is round to be varied with changing in intensity of optical illumination.

• Journal of Magnetics
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• v.19 no.2
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• pp.116-120
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• 2014

The spin-lattice relaxation time, $T_1$, for $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei in GaAs:$Mn^{2+}$ single crystals was measured as a function of temperature. The values of $T_1$ for $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei were found to decrease with increasing temperature. The $T_1$ values in GaAs:$Mn^{2+}$ crystal are similar to those in pure GaAs crystal. The calculated activation energies for the $^{69}Ga$, $^{71}Ga$, and $^{75}As$ nuclei are 4.34, 4.07, and 3.99 kJ/mol. It turns out that the paramagnetic impurity effect of $Mn^{2+}$ ion doped in GaAs single crystal was not strong on the spin-lattice relaxation time.

• Korean Journal of Optics and Photonics
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• v.11 no.5
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• pp.360-364
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• 2000

We demonstrate self-starting passIve mode locking of a Cr:LiSAF laser, using a SCIDlconduclor Saturable Absorber Mirror (SESAM), Two high-power red semiconductor lasers (Coherent S-67-500C-100-H) of wavelength 667 nm and maximum power of 500 mW were used as pump lasers, The cavity has 10 cm radius-ai-curvature folding minors, two SF 10 prisms, a 99% reflectivity output coupler and a SESAM at dIe focus of a 10 cm radIus-at-curvature mirror. We used the laser crystal in BrewsterBrewster shape with 1 5% $Cr^{+3}$ ion concentration and the length of 6 mm, An X-shaped resonator was used to compensate the astigmatism induced by tile crystal. The structure of the SESAM cOllSists of 30 pmr of $AlAs/Al_{0.15}Ga_{0.85}As$ layer, wi1l1 a 10 nm GaAs quantum well situated in the topmost layer Output spectra were centeled at 833 nm, with 4 nm spectral bandwidth and pulse width was measured to be 220 fs, Output power of 3 mW is obtained at a pump power of 800 mW. 00 mW.

• Journal of the Korean Vacuum Society
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• v.18 no.4
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• pp.266-271
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• 2009

We have investigated the lasing characteristics of GaAs-based 1300 nm wavelength region InAs Quantum Dot Laser Diode grown by Migration Enhanced Molecular Beam Epitaxy. Under a pulsed and CW operation, we observed the state switching of lasing wavelength from ground state (1302 nm) to excited state (1206 nm) due to the gain saturation of ground state. Under a pulsed operation, $J_{th}=92A/cm^2$, $\lambda_L=1311\;nm$ and under a CW operation, $J_{th}=247A/cm^2$, $\lambda_L=1320\;nm$.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.266-271
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• 1996

In this study the evaluation of RWG MQW-LD fabricated with our vertical LPE system has been carried out with measuring its optical characteristics. This laser diode operated in lateral single mode as designed, and it showed 77% of internal quantum efficiency, 18cm of internal loss and 5.5$\AA$/$^{\circ}C$ of the thermal characterictic of the lasing wavelength. From these results we conclude that the vertical LPE system are fairly good and it might he useful to fabricate MQW wafer for laser diode.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.6
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• pp.286-292
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• 2005

Terahertz wave is a kind of electromagnetic radiation whose frequency lies in 0.1THz $\~$10THz range. In this paper, generation and detection characteristics of terahertz (THz) radiation by photoconductive antenna (PCA) method has been described. Using modern integrated circuit techniques, micron-sized dipole antenna has been fabricated on a low-temperature grown GaAs (LT-GaAs) wafer. A mode-locked Ti:Sapphire femtosecond laser beam is guided and focused onto photoconductive antennas (emitter and detector) to generate and measure THz pulses. Ultra-wide band THz radiation with frequencies between 0.1 THz and 3 THz was observed. Terahertz field amplitude variation with antenna bias voltage, pump laser power, pump laser wavelength and probe laser power was investigated. As a primary application example. a live clover leaf was imaged with the terahertz radiation.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.97-97
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• 1996