Browsing by Author "Chen, Cheng-Yuan"

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Design and Fabrication of the Reliable GaN Based Vertical-Cavity Surface-Emitting Laser via Tunnel Junction
(2019-04-01)
Shen, Chih-Chiang
;
Lu, Yun-Ting
;
Yeh, Yen-Wei
;
Chen, Cheng-Yuan
;
Chen, Yu-Tzu
In this study, we theoretically designed and experimentally fabricated an InGaN vertical-cavity surface-emitting laser (VCSEL) with a tunnel junction (TJ) structure. From numerical simulation results, the optical loss of the device can be reduced by a TJ structure. Additionally, the leakage current of the VCSEL with TJ structure was much smaller than that of the VCSEL with an Indium-Tin-Oxide (ITO) layer. We have been demonstrated that laser output performance is improved by using the TJ structure when compared to the typical VCSEL structure of the ITO layer. The output power obtained at 2.1 mW was enhanced by a factor of 3.5 by the successful reduction of threshold current density (J(th)) from 12 to 8.5 kA/cm(2), and the enlarged slope efficiency was due to less absorption in VCSEL with a TJ structure. Finally, the samples passed the high temperature (70 degrees C) and high operation current (1.5 x J(th)) test for over 500 h.
Design, Modeling, and Fabrication of High-Speed VCSEL with Data Rate up to 50 Gb/s
(2019-08-14)
Shen, Chih-Chiang
;
Hsu, Tsung-Chi
;
Yeh, Yen-Wei
;
Kang, Chieh-Yu
;
Lu, Yun-Ting
We have studied the characteristics of frequency response at 850-nm GaAs high-speed vertical-cavity surface-emitting lasers (VCSELs) with different kinds of oxide aperture sizes and cavity length using the PICS3D simulation program. Using 5-mu m oxide aperture sizes, the frequency response behavior can be improved from 18.4 GHz and 15.5 GHz to 21.2 GHz and 19 GHz in a maximum of 3 dB at 25 degrees C and 85 degrees C, respectively. Numerical simulation results also suggest that the frequency response performances improved from 21.2 GHz and 19 GHz to 30.5 GHz and 24.5 GHz in a maximum of 3 dB at 25 degrees C and 85 degrees C due to the reduction of cavity length from 3 lambda/2 to lambda/2. Consequently, the high-speed VCSEL devices were fabricated on a modified structure and exhibited 50-Gb/s data rate at 85 degrees C.
High Color Conversion Efficiency on Monolayer WSe2 Using Plasmonic Metasurface
(2019-01-01)
Chen, Cheng-Yuan
;
Lin, Chen-An
;
Lin, Hsiang-Ting
;
Chang, Chiao-Yun
;
Kuo, Hao-Chung
The atomic scale thickness transition metal dichalcogenides (TMDCs) material could be a potential role of miniature light emitting devices (LED). The high color conversion efficiency between CdSe quantum dot (QD) and monolayer tungsten diselenide (WSe2) with Ag NDs metasurface could enhance the light emission of WSe2. The emission enhancement presented the color conversion due to its absorption spectrum of Ag ND. It had the most ideal overlap with QDs and WSe2 simultaneously, which boosted all the effects that would happen in color conversion. In the future, utilizing plasmonic metasurface and combing the TMDCs emitting visible red light with the GaN-based LED and green QDs to helpfully achieve white light emitting device. (C) 2019 The Author(s)