Browsing by Author "Shih, M. H."

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A Full-Color, White Light Emission of Quantum-Dot-Based Display Technology Using Pulsed Spray Method with Distributed Bragg Reflector
(2012)
Chen, K. J.
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Chen, H. C.
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Lin, C. C.
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Tsai, H. H.
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Tsai, K. A.
A colloidal quantum dot light-emitting multi-layer structure with HFO2/SiO2 distributed Bragg reflector is manufactured by pulse spray method. A pure white light with strong enhancement due to better utilization of UV pump was demonstrated. (C)2012 Optical Society of America
Compact microdisk cavity laser with type-II GaSb/GaAs quantum dots
(2011-01-31)
Hsu, K. S.
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Chiu, T. T.
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Lin, Wei-Hsun
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Chen, K. L.
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Shih, M. H.
Microdisk lasers with active region made of type-II GaSb/GaAs quantum dots on the GaAs substrate have been demonstrated. A microdisk cavity with diameter of 3.9 mu m was fabricated from a 225-nm-thick GaAs layer filled with GaSb quantum dots. Lasing at wavelengths near 1000 nm at 150 K was achieved for this microdisk. A high threshold characteristic temperature of 77 K was also observed. It is found that the lasing wavelength matches closely with the first-order whispering-gallery mode of the cavity as obtained from the finite-element method simulation. (c) 2011 American Institute of Physics. [doi: 10.1063/1.3543839]
Compact optical curvature sensor with a flexible microdisk laser on a polymer substrate
(2009-09-15)
Shih, M. H.
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Hsu, K. S.
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Kunag, Wan
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Yang, Y. C.
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Wang, Y. C.
We demonstrate a chip-scale compact optical curvature sensor. It consists of a low threshold InGaAsP microdisk laser on a flexible polydimethylsiloxane polymer substrate. The curvature dependence of lasing wavelength was characterized by bending the cavity at different bending radii. The measurements showed that the lasing wavelength decreases monotonously with an increasing bending curvature. A good agreement between experiment and three-dimensional finite-difference time-domain simulation was also obtained. The sensitivity of the compact device to the bending curvature is -23.7 nm/mm from the experiment. (C) 2009 Optical Society of America
Design and fabrication of a InGaN vertical-cavity surface-emitting laser with a composition-graded electron-blocking layer
(2014-08-01)
Lin, B. C.
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Chang, Y. A.
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Chen, K. J.
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Chiu, C. H.
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Li, Z. Y.
In this study, the design and fabrication of a InGaN vertical-cavity surface-emitting laser (VCSEL) with a composition-graded electron blocking layer (GEBL) are revealed experimentally and theoretically. It has been demonstrated that laser output performance is improved by using a GEBL when compared to the typical VCSEL structure of a rectangular EBL. The output power obtained at 20 kA cm(-2) is enhanced by a factor of 3.8 by the successful reduction of threshold current density from 12.6 to 9.2 kA cm(-2) and the enlarged slope efficiency. Numerical simulation results also suggest that the improved laser output performances are due mainly to the reduction of electron leakage current and the enhanced hole injection efficiency in the multiple-quantum-well (MQW) active region.
Effect of the Thermal Characteristics of Phosphor for the Conformal and Remote Structures in White Light-Emitting Diodes
(2013-10-01)
Chen, K. J.
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Lin, B. C.
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Chen, H. C.
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Shih, M. H.
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Wang, C. H.
The influence of the thermal effect of phosphor for conformal and remote structures in white light-emitting diodes was investigated using the junction and phosphor temperatures. Comparing the measured temperatures with IR thermometer, the remote structure has a higher phosphor temperature than the conformal structure. This result indicates that the phosphor in the conformal structure has demonstrated superior conduction because of the high thermal conductivity in surrounding. Furthermore, thermal distribution in the simulation results has shown to have favorable agreement with the experimental results. Consequently, the lifetime measurement is shown to verify the results of the simulation and experiment for both structural types.
Excellent Color Rendering Index Quantum Dots White Light-Emitting Diode with Distributed Bragg Reflector Structure
(2014)
Chen, K. J.
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Lin, B. C.
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Han, H. V.
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Lin, C. C.
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Lee, C. Y.
This study demonstrated the high CRI and excellent uniformity colloidal quantum dot white-light-emitting diodes with the DBR structure at different correlated color temperature from 2500 K to 4500K.
Flexible compact microdisk lasers on a polydimethylsiloxane (PDMS) substrate
(2009-01-19)
Shih, M. H.
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Hsu, S.
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Wang, Y. C.
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Yang, Y. C.
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Tsai, S. K.
Compact microdisk cavities were fabricated on a polydimethylsiloxane substrate. The lasing of the flexible compact cavity was achieved with a low threshold power. The whispering-gallery mode of the microdisk was also characterized with three-dimensional finite-difference time-domain simulation. The curvature dependence in output power and threshold was also demonstrated by bending the microdisk cavity. (C) 2008 Optical Society of America
Flexible compact microdisk lasers on a polydimethylsiloxane (PDMS) substrate
(2009-01-19)
Shih, M. H.
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Hsu, S.
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Wang, Y. C.
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Yang, Y. C.
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Tsai, S. K.
Compact microdisk cavities were fabricated on a polydimethylsiloxane substrate. The lasing of the flexible compact cavity was achieved with a low threshold power. The whispering-gallery mode of the microdisk was also characterized with three-dimensional finite-difference time-domain simulation. The curvature dependence in output power and threshold was also demonstrated by bending the microdisk cavity. (C) 2008 Optical Society of America
Flexible Photonic Crystal Defect Lasers on a Polydimethylsiloxane Polymer Substrate
(2010)
Hsu, K. S.
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Yang, Y. C.
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Tsai, Y. Y.
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Shih, M. H.
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Wu, M. C.
We demonstrated a flexible photonic crystal defect laser on a polydimethylsiloxane (PDMS) polymer substrate. The curvature dependences of lasing power and threshold were also characterized by bending the photonic crystal cavity at different bending curvatures. (C) 2010 Optical Society of America
Highly Efficient GaAs Solar Cells with Dual Layer of Quantum Dots And A Flexible PDMS Film
(2012)
Lin, Chien-chung
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Chen, H. C.
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Chen, K. J.
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Han, H. V.
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Kuo, H. C.
High performance of GaAs solar cell with dual layer quantum dots separated by flexible polydimethylsiloxane film was demonstrated. By this scheme, the efficiency increased by 22 %, compared to the cell without QDs. (C) 2012 Optical Society of America
Hybrid White Light-emitting Diodes by Organic-Inorganic materials
(2015)
Chen, K. J.
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Lai, Y. C.
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Lin, B. C.
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Lin, C. C.
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Chiu, S. H.
This study demonstrated the high uniformity hybrid white light-emitting didoes with polyfluoren (PFO) polymer and quantum dot (QD) with different CCT range from 3000K to 9000K.
Improvement of Angular-dependent CCT Uniformity by ZrO2 Nano-particles in Remote Phosphor White LEDs
(2012)
Chen, H. C.
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Chen, K. J.
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Wang, C. H.
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Tsai, H. H.
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Lin, C. C.
The superior uniformity of angular-dependent CCT white LEDs have been investigated by ZrO2-type remote phosphor structure. This novel structure reduces angular-dependent CCT deviations from 1000K to 420K in range of -70 to 70 degrees. (C)2012 Optical Society of America
Improvement of lumen efficiency in white light-emitting diodes with air-gap embedded package
(2012-05-01)
Chen, H. C.
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Chen, K. J.
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Lin, C. C.
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Wang, C. H.
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Yeh, C. C.
In this paper, white light-emitting diodes (LEDs) with air-gap embedded package were proposed and fabricated by a simple method including pulsed spray coating. The lumen efficiency of air-gap embedded LED was enhanced by 8.8% at driving current of 350 mA, compared to conventional remote phosphor white LED. This improvement was due to the enhanced utilization of blue and yellow rays, which were confirmed by pulse current-dependent correlated color temperature (CCT). The utilization efficiency of blue rays was enhanced by 12.4% due to the embedded air-gap layer. The simulation results performed by Monte-Carlo ray tracing method agreed with our experiments, which showed enhancement in lumen efficiency and similar CCT. Finally, the electric field intensity versus different thickness for air-gap and no air-gap embedded white LED was calculated to check the incident blue rays trapped in phosphor layer. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
Large Area of Ultraviolet GaN-Based Photonic Quasicrystal Laser
(2012-04-01)
Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Tu, Po-Min
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Kuo, Ming-Yen
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Shih, M. H.
In this study, large-area GaN-based photonic quasicrystal (PQC) nanopillars were fabricated on an n-GaN substrate using the nanoimprint lithography (NIL) technique. Under optical pumping condition, a high lasing action from the GaN photonic quasicrystals was observed. The lasing wavelength is at 366nm with a low threshold power density of 0.009 kW/cm(2). To confirm the band-edge lasing mode, the finite-element method (FEM) was used to perform the simulation for the 12-fold symmetry photonic quasicrystal lattices. (C) 2012 The Japan Society of Applied Physics
Large-area ultraviolet GaN-based photonic quasicrystal laser with high-efficiency green color emission of semipolar {10-11} In0.3Ga0.7N/GaN multiple quantum wells
(2013-01-07)
Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Chang, Shih-Pang
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Shih, M. H.
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Kuo, Ming-Yen
In this study, a multi-color emission was observed from the large-area GaN-based photonic quasicrystal (PQC) nanopillar laser. The GaN PQC nanostructure was fabricated on an n-GaN layer by using nanoimprint lithographic technology. The regrown InGaN/GaN multiple quantum wells (MQWs) formed a nanopyramid structure on top of the PQC nanopillars. A lasing action was observed at ultraviolet wavelengths with a low threshold power density of 24 mJ/cm(2), and a green color emission from InGaN/GaN MQWs was also achieved simultaneously. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4775373]
Lasing in metal-coated GaN nano-stripe at room temperature
(2011-01-01)
Wang, Y. G.
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Chen, C. C.
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Chiu, C. H.
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Kuo, M. Y.
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Shih, M. H.
We demonstrated lasing in a metal-coated GaN nano-stripe under room temperature pulsed operation, and the lasing mode at 370nm were observed. Aluminum and SiO2 layers were coated on the undoped GaN nano-stripe. (C) 2010 Optical Society of America
Lasing in metal-coated GaN nanostripe at room temperature
(2011-03-28)
Wang, Yow-Gwo
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Chen, Cheng-Chang
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Chiu, Ching-Hsueh
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Kuo, Ming-Yen
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Shih, M. H.
This study demonstrated a metal-coated GaN nanostripe laser operable at room temperature. The ultraviolet lasing mode was observed at a wavelength of approximately 370 nm with a low threshold power density of 0.042 kW/cm(2). The lasing mode of the metal-coated nanostripe was characterized using finite-element method simulation. The results showed the significance of metal coatings in this nanocavity structure for lasing at room temperature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3572023]
Light Enhancement of Silicon-Nanocrystal-Embedded SiO(x) Film on Silicon-on-Insulator Substrate
(2011-04-01)
Chen, Cheng-Chang
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Lin, Yung-Hsaing
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Shih, M. H.
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Lin, Gong-Ru
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Kuo, Hao-Chung
We reported the light enhancement from a silicon-nanocrystal-embedded SiO(x) film on a silicon-on-insulator (SOI) substrate in the visible light range. The light emission from the annealed SiO(x) film is one order stronger than the emission from a nonannealed SiO(x) film. Compared with the SiO(x) film on a Si substrate, two-fold enhancement in light emission from the SiO(x) film on a SOI substrate was also observed. The enhancement was attributed to better vertical confinement of optical field in the SiO(x) film on a SOI substrate. (C) 2011 The Japan Society of Applied Physics
Light Enhancement of Silicon-Nanocrystal-Embedded SiOx Film on Silicon-on-Insulator Substrate
(2011-04-01)
Chen, Cheng-Chang
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Lin, Yung-Hsaing
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Shih, M. H.
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Lin, Gong-Ru
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Kuo, Hao-Chung
We reported the light enhancement from a silicon-nanocrystal-embedded SiOx film on a silicon-on-insulator (SOI) substrate in the visible light range. The light emission from the annealed SiOx film is one order stronger than the emission from a nonannealed SiOx film. Compared with the SiOx film on a Si substrate, two-fold enhancement in light emission from the SiOx film on a SOI substrate was also observed. The enhancement was attributed to better vertical confinement of optical field in the SiOx film on a SOI substrate. (C) 2011 The Japan Society of Applied Physics
Long Photon Lifetime from Microdisk Cavity Laser with Type II GaSb/GaAs Quantum Dots
(2013-01-01)
Hsu, K. S.
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Chang, C. C.
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Lin, W. H.
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Shih, M. H.
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Lin, S. Y.
Microdisk lasers with active region made of type II GaSb/GaAs quantum dots on the GaAs substrate have been demonstrated. Lasing wavelengths near 1 mu m was achieved and longer photon lifetime from type II structure also observed. (C) 2013 Optical Society of America