• Journal of Sensor Science and Technology
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• v.11 no.1
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• pp.60-65
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• 2002

$ZnGa_2O_4$ thin film phosphors have been deposited using a pulsed laser deposition method on Si(100) substrates at a substrate temperature of $550^{\circ}C$ with oxygen pressures of 100mTorr, and subsequently to investigate their photoluminescence characteristics after post-annealed at $600^{\circ}C$ and $700^{\circ}C$. As a result for X-ray diffraction, $Ga_2O_3$ shape appeared with increasing annealing temperature. The luminescent spectra show a broad band extending from 350 to 600nm peaking at 460nm. A post-annealing treatment of $ZnGa_2O_4$ thin films led to the different shape of luminescent intensity and grain size.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.48-49
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• 2006

Highly conductive and transparent films of Ga-doped ZnO have been prepared by pulsed laser deposition using a ZnO target with 3 wt% ${Ga_2}{O_3}$ dopant. Films with the resistivity as low as $3.3{\times}10^{-4}{\Omega}cm$ and the transmittance above 80 % at the wavelength of 400 to 800 nm can be fabricated on glass substrate at room temperature. It is shown that a stable resistivity for the use in oxidation ambient at high temperature can be obtained for the films. Heat treatments were performed to examine the thermal stability of ZnO and GZO films at ptemperature range from $100^{\circ}C$ to $400^{\circ}C$ in $O_2$ ambient for 30 minutes. The resistivity of ZnO film annealed at $400^{\circ}C$ increased by two orders of magnitude, in case of GZO film was relatively stable up to at $400^{\circ}C$. For practical applications at high temperatures the thermal stability of resistivity of GZO thin films might become an advantage for transparent electrodes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.40-46
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• 2006

Latching optical switches and optical logic gates AND and OR are demonstrated, for the first time, by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure, which have not only a low threshold current with 0.65mA, but also a high on/off contrast ratio more than 50dB. By simple operating technique with changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated using the oxidation process achieved a high optical output power efficiency and a high sensitivity to the optical input light.

• Journal of the Korean Ceramic Society
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• v.33 no.3
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• pp.313-320
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• 1996

We have fabricated an in-plane aligned a-axis oriented YBa2Cu3O7-x (a-YBCO) thin film on a LaSrGaO4(100) substrate with a PrBa2Cu3O7-x(PBCO) template layer by two step plused laser deposition using 308 nm XeCl excimer laser. A YBCO layer and PBCO layer grown at low temperatures were used as template layers. We have investigated the effect of the deposition temperature of template layers on the superconducting and struc-tural properties of in-plane aligned a-YBCO thin films. An optimal deposition temperature of the PBCO template layers was 630. In-plane aligned a-YBCO thin films showed an anisotropy ratio in resistivity of 11.5 and a zero resistance temperature of 88 K.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.233-234
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• 2009

In this paper, we report the characteristics of the continuous wave laser output of the $lima{\varsigma}on$-shaped InGaAsP microcavity laser pumped by current injection. In order to find the directions of emission far-field patterns are measureed by rotating an optical fiber around the microcavity. We observe high directionality of the $lima{\varsigma}on$-shaped microcavity laser. For the analysis of lasing properties we also investigate its polarization and spectrum using the Glan-Thompson polarizer and spectrum analyzer.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.286-291
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• 2003

Asymmetric multiple quantum well ridge waveguide laser diodes (AMQW RWG LDs) with a wide and flat gain spectrum were designed and fabricated. The operating parameters and gain spectra were measured and analyzed for uncoated and anti-reflection (AR) coated LDs. For AR coated 500 mm-long RWG LOs, the extremely flat gain spectrum over a spectral range of 90 nm was obtained at the current 75 ㎃.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.99-99
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• 2008

To grow the large diameter GaN with high structure and optical quality has been obtained by hydride vapor phase epitaxy(HVPE) method. In addition to the nitridation of $Al_2O_3$ substrate, we also developed a "step-growth process" to reduce or to eliminate the bowing of the GaN substrate caused by thermal mismatch during cool down after growth. The as-grown 380um thickness and 75mm diameter GaN layer was separated from the sapphire substrate by laser-induced lift-off process at $600^{\circ}C$. A problem with the free-standing wafer is the typically large bowing of such a wafer, due to the built in the defect concentration near GaN-sapphire interface. A polished G-surface of the GaN substrate were characterized by room temperature Double crystal X-ray diffraction (DCXRD), photoluminescence(PL) measurement, giving rise to the full-width at half maximum(FWHM) of the rocking curve of about 107 arcsec and dislocation density of $6.2\times10^6/cm^2$.

• Physical Therapy Korea
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• v.5 no.2
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• pp.15-22
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• 1998

Laser photobiostimulation (LPBS) is one of the recent additions to therapeutic procedures used in chronic pain management. Though widely used, a clear understanding of its mechanism of action was not disclosed. In addition, the energy density that produces maximal benefit has not yet been established. The purposes of this study were to determine the effects of LPBS on pain relief in rat and to determine treatment dosage. Eight, 8-week old female, Sprague-Dawley rats were employed. All subjects were assigned to one of four groups: a sham laser group, a 0.4 $J/cm^2$ laser group, a 2.0 $J/cm^2$ laser group, and a 6.0 $J/cm^2$ laser group. Ga-As laser (904 nm wavelength) of three different energy densities (0.4, 2.0, 6.0 $J/cm^2$) was applied on a tail acupuncture point and tail-flick latencies were measured five times pre-and post-treatment as following schedules: 30 minutes, 1 hour. 24 hours. 48 hours, and 7 days later. An increase in pain threshold was demonstrated following LPBS, employing rat tail-flick test. LPBS of 2.0 $J/cm^2$ produced hypoalgesia of rapid onset and short duration (1 hour, 24 hours) while the response to 6.0 $J/cm^2$ was delayed and lasted longer (48 hours, 7 days). LPBS of 0.4 $J/cm^2$ did not produce any hypoalgesia.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.1-8
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• 2013

In this paper, we report design, fabrication and characterization of the WBRM (Wide Band Receiver Module) for LADAR (LAser Detection And Ranging) application. The WBRM has been designed and fabricated using self-made APD (Avalanche Photodiode) and TIA (Trans-impedance Amplifier). The APD and TIA chips have been integrated on 12-pin TO8 header using self-made ceramic submount and circuit. The WBRM module showed 450 ps of rise time, and corresponding 780 MHz bandwidth. Furthermore, it showed very low output noise less than 0.8 mV, and higher SNR than 15 for 150 nW of MDS(Minimum Detectable Signal). To the author's knowledge, this is the best performance of an optical receiver module for LIDAR fabricated by 200 um InGaAs APD.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.434-436
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• 2013

Ga-doped ZnO (GZO) was substitutes of the SnO2:F films on soda lime glass substrate in the photovoltaic devices such as CIGS, CdTe and DSSC due to good properties and low cost. However, it was reported that the electrical resistivity of GZO is unstable above $300^{\circ}C$ in air atmosphere. To improve thermal stability of GZO thin films at high temperature above $300^{\circ}C$ an $TiO_2$ thin film was deposited on the top of GZO thin films as a barrier layer by Pulsed Laser Deposition (PLD) method. $TiO_2$ thin films were deposited at various thicknesses from 25 nm to 100 nm. Subsequently, these films were annealed at temperature of $300^{\circ}C$, $400^{\circ}C$, $500^{\circ}C$ in air atmosphere for 20 min. The XRD measurement results showed all the films had a preferentially oriented ( 0 0 2 ) peak, and the intensity of ( 0 0 2 ) peak nearly did not change both GZO (300 nm) single layer and $TiO_2$ (50 nm)/GZO (300 nm) double layer. The resistivity of GZO (300 nm) single layer increased from $7.6{\times}10^{-4}{\Omega}m$ (RT) to $7.7{\times}10^{-2}{\Omega}m$ ($500^{\circ}C$). However, in the case of the $TiO_2$ (50 nm)/GZO (300 nm) double layer, resistivity showed small change from $7.9{\times}10^{-4}{\Omega}m$ (RT) to $5.2{\times}10^{-3}{\Omega}m$ ($500^{\circ}C$). Meanwhile, the average transmittance of all the films exceeded 80% in the visible spectrum, which suggests that these films will be suitable for photovoltaic devices.