Browsing by Author "Li, Zong-Lin"

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Dual-wavelength GaSb-based mid infrared photonic crystal surface emitting lasers
(2018-03-07)
Li, Zong-Lin
;
Chang, Bing-Hui
;
Lin, Chien-Hung
;
Lee, Chien-Ping
;
電機學院
We demonstrate dual-wavelength GaSb-based mid-infrared photonic crystal surface emitting lasers at room temperature. The two lasing peaks emitted simultaneously at 2.3 mu m and 2.22 mu m under optical pumping. Type-I InGaAsSb quantum wells were used for the active region. The photonic crystal with a rectangular lattice was fabricated on the surface to provide light coupling for laser operation. The two-wavelength operation was a result of the resonances from the two different grating periods along the two perpendicular directions of the rectangular lattice. The laser emissions from these two wavelengths were highly linearly polarized in two perpendicular directions as a result of the grating design. Published by AIP Publishing.
Effect of Etching Depth on Threshold Characteristics of GaSb-Based Middle Infrared Photonic-Crystal Surface-Emitting Lasers
(2019-03-14)
Li, Zong-Lin
;
Lin, Shen-Chieh
;
Lin, Gray
;
Cheng, Hui-Wen
;
Sun, Kien-Wen
We study the effect of etching depth on the threshold characteristics of GaSb-based middle infrared (Mid-IR) photonic-crystal surface-emitting lasers (PCSELs) with different lattice periods. The below-threshold emission spectra are measured to identify the bandgap as well as band-edge modes. Moreover, the bandgap separation widens with increasing etching depth as a result of enhanced diffraction feedback coupling. However, the coupling is nearly independent of lattice period. The relationship between threshold gain and Bragg detuning is also experimentally determined for PCSELs and is similar to that calculated theoretically for one-dimensional distributed feedback lasers.
Long-wavelength mid-infrared reflectors using guided-mode resonance
(2013-10-01)
Lai, Kou-Wei
;
Lin, Sheng-Di
;
Li, Zong-Lin
;
Wang, Chi-Cheng
;
電子工程學系及電子研究所
We have proposed and fabricated a new mid-infrared reflector using the guided-mode resonance (GMR). The GMR reflector consists of subwavelength Ge grating on GaAs substrate with a low-refractive-index SiOx layer in between. With a total thickness of about 2 mu m, a near-100% reflectivity at 8 mu m has been obtained both theoretically and experimentally. (C) 2013 Optical Society of America
Low-threshold InGaAs/GaAsSb \'W\'-type quantum well laser on InP substrate
(2014)
Chang, Chia-Hao
;
Li, Zong-Lin
;
Lu, Hong-Ting
;
Lee, Chien-Ping
;
Lin, Sheng-Di
The mid-infrared electrically-driven laser using InGaAs/GaAsSb \'W\'-type QWs is demonstrated at room temperature. The InP-based laser lasing at 2.35 mu m with the lowest threshold current density of 1.42 kA/cm(2) is presented.
Low-Threshold Short-Wavelength Infrared InGaAs/GaAsSb \'W\'-Type QW Laser on InP Substrate
(2015-02-01)
Chang, Chia-Hao
;
Li, Zong-Lin
;
Lu, Hong-Ting
;
Pan, Chien-Hung
;
Lee, Chien-Ping
The electrically driven short-wavelength infrared semiconductor laser using InP-based InGaAs/GaAsSb W-type quantum wells (QWs) is investigated. Using Sb-free separate confined layer and engineered QWs, the laser lasing at 2.35 mu m exhibits a low-threshold current density at infinite cavity length of 83 A/cm(2) per QW under pulsed operation at room temperature. The internal loss alpha(i) and internal quantum efficiency eta(i) of the laser are 17.5 cm(-1) and 15%, respectively.
Mid-Infrared Photonic-Crystal Surface-Emitting Lasers with InGaAs/GaAsSb 'W'-Type Quantum Wells Grown on InP Substrate
(2018-12-01)
Li, Zong-Lin
;
Kang, Yuan-Chi
;
Lin, Gray
;
Lee, Chien-Ping
;
電子工程學系及電子研究所
InP-based InGaAs/GaAsSb 'W'-type quantum well (QW) photonic-crystal (PC) surface-emitting lasers (SELs) of 2.2 mu m wavelength range are fabricated and room-temperature lasing emissions by optical pumping are demonstrated for the first time. Photonic-crystal surface-emitting laser (PCSEL) devices are investigated in terms of PC parameters of etch depth, lattice period, and filling factor. The lasing emissions cover wavelengths from 2182 nm to 2253 nm. The temperature-dependent lasing characteristics are also studied in terms of lattice period. All PCSELs show consistent lasing wavelength shift against temperature at a rate of 0.17 nm/K. The characteristic temperatures of PCSELs are extracted and discussed with respect to wavelength detuning between QW gain peak and PC cavity resonance.
PCSEL Performance of Type-I InGaAsSb Double-QWs Laser Structure Prepared by MBE
(2019-01-02)
Cheng, Hui-Wen
;
Lin, Shen-Chieh
;
Li, Zong-Lin
;
Sun, Kien-Wen
;
Lee, Chien-Ping
This paper discusses the issue of controlling the epitaxial growth of mixed group V alloys to form a type-I InGaAsSb/AlGaAsSb double quantum wells (QWs) structure. We also discuss the run-to-run reproducibility of lattice-matched AlGaAsSb alloys and strained In0.35Ga0.65As0.095Sb0.905 in terms of growth parameters (V/III ratio, Sb-2/As-2 ratio). Molecular beam epitaxy (MBE) was used to grow two type-I InGaAsSb double-QWs laser structures differing only in the composition of the bottom cladding layer: Al0.85Ga0.15As0.072Sb0.928 (sample A) and Al0.5Ga0.5As0.043Sb0.957 (sample B). Both samples were respectively used in the fabrication of photonic crystal surface-emitting lasers (PCSELs). Sample A presented surface lasing action from circular as well as triangular photonic crystals. Sample B did not present surface lasing due to the deterioration of the active region during the growth of the upper cladding. Our findings underline the importance of temperature in the epitaxial formation of AlxGa1-xAsySb1-y in terms of lasing performance.
Photonic Crystal Surface Emitting Lasers With Quantum Dot Active Region
(2017-10-15)
Chen, Tzu-Shan
;
Li, Zong-Lin
;
Hsu, Ming-Yang
;
Lin, Gray
;
Lin, Sheng-Di
GaAs-based InAs/InGaAs/GaAs quantum dot (QD) photonic crystal (PC) surface emitting lasers of 1.3 mu m wavelength range are fabricated and room-temperature lasing emissions by optical pumping are demonstrated for the first time. Laser devices are characterized in terms of PC parameters and temperature-dependent measurements are also carried out. The impact of wavelength detuning between PC resonant wavelength and QD gain peak is manifested in the experiments. Moreover, simplified simulation reveals that etched PC depth plays an even more critical role in active region of QD compared to that of quantum well.
Relationship between Threshold Gain and Bragg Detuning in Photonic-Crystal Surface-Emitting Lasers
(2019-01-01)
Li, Zong-Lin
;
Lin, Shen-Chieh
;
Chen, Yu-Chen
;
Lin, Gray
;
電子工程學系及電子研究所
The device characteristics of GaSb-based mid-infrared (MIR) photonic-crystal (PC) surface-emitting lasers (SELs) were investigated with respect to depths of etched PC holes. Measurement of below-threshold emission spectra identifies the bandgap as well as band-edge modes. The bandgap separation, which is a function of feedback coupling, increases with increasing depth. From within, the Bragg frequencies and their detuning from lasing frequencies can be determined. Moreover, with increasing depth, the threshold pumping density decreases exponentially to a saturation level, which is assigned to minimum device modal gain of certain value. The relative threshold gain is then plotted as a function of normalized frequency detuning. The gain-detuning relationship of PCSELs is similar to that of one-dimensional (1D) distributed feedback (DFB) lasers.
Room-temperature mid-infrared "M"-type GaAsSb/InGaAs quantum well lasers on InP substrate
(2014-02-14)
Chang, Chia-Hao
;
Li, Zong-Lin
;
Pan, Chien-Hung
;
Lu, Hong-Ting
;
Lee, Chien-Ping
We have demonstrated experimentally the InP-based "M"-type GaAsSb/InGaAs quantum-well (QW) laser lasing at 2.41 mu m at room temperature by optical pumping. The threshold power density per QW and extracted internal loss were about 234 W/cm(2) and 20.5 cm(-1), respectively. The temperature-dependent photoluminescence (PL) and lasing spectra revealed interesting characteristics for this type of lasers. Two distinct regions in the temperature dependent threshold behavior were observed and the transition temperature was found to coincide with the cross over point of the PL and lasing emission peaks. The current-voltage characteristic of "M"-type QW laser was superior to the inverse "W"-type one due to its thinner barrier for holes. Further improvement of the "M"-type QW structure could lead to a cost-effective mid-infrared light source. (C) 2014 AIP Publishing LLC.
Threshold current temperature dependence of quantum-dot photonic crystal surface-emitting lasers with respect to gain-cavity detuning
(2018-05-14)
Hsu, Ming-Yang
;
Lin, Gray
;
Li, Zong-Lin
;
Pan, Po-Chou
;
電機學院
We investigate threshold current temperature dependence of electrically injected quantum-dot (QD) photonic crystal (PC) surface-emitting lasers (SELs) with respect to wavelength detuning between QD gain peak and PC cavity resonance. The lasing emissions cover wavelengths from 1283 nm to 1318 nm. Almost infinite characteristic temperature is realized at certain temperature range for PCSEL with large negative gain-cavity detuning. Moreover, band-edge lasing mode is identified in our "PC slab-on-substrate" structure, and its far-field distribution is characterized as doughnut-shaped beam with azimuthal polarization. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement