Browsing by Author "Lin, Gray"

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A simple model for cavity enhanced slow lights in vertical cavity surface emission lasers
(2008-04-01)
Chou, Chia-Sheng
;
Lee, Ray-Kuang
;
Peng, Peng-Chun
;
Kuo, Hao-Chung
;
Lin, Gray
We develop a simple model for the slow lights in vertical cavity surface emission lasers (VCSELs), with the combination of cavity and population pulsation effects. The dependences of probe signal power, injection bias current and wavelength detuning for the group delays are demonstrated numerically and experimentally. Up to 65 ps group delays and up to 10 GHz modulation frequency can be achieved at room temperature at a wavelength of 1.3 mu m. The most significant feature of our VCSEL device is that the thickness of the active region is only several micrometers long. Based on the experimental parameters of quantum dot VCSEL structures, we show that the resonance effect of the laser cavity plays a significant role in enhancing the group delays.
Analysis of Relative Intensity Noise Spectra for Uniformly and Chirpily Stacked InAs-InGaAs-GaAs Quantum Dot Lasers
(2012-02-01)
Lin, Gray
;
Tang, Hao-Ling
;
Cheng, Hsu-Chieh
;
Chen, Hung-Lin
;
電子工程學系及電子研究所
The dynamic properties of uniformly and chirpily stacked InAs-InGaAs-GaAs quantum dot lasers are analyzed in terms of relative intensity noise spectra. For uniformly stacked quantum dot laser with ground-state lasing emissions of 1.3 mu m, the K-factor limited bandwidth is 13 GHz. The extracted differential gain and gain compression factor are 1.7 x 10(-15) cm(2) and 2 x 10(-16) cm(3), respectively. For chirpily stacked quantum dot laser with excited-state lasing emissions of 1.2 mu m, the K-factor limited bandwidth is 14 GHz. Yet the nonproportional dependence between resonance frequency and square root of incremental current yields differential gain of 4.3 x 10(-15) cm(2) and huge gain compression factor of 1.4 x 10(-14) cm(3).
Beam profile characteristics of InGaAs sub-monolayer quantum-dot photonic-crystal VCSELs
(2007-06-01)
Yang, Hung-Pin D.
;
Hsu, I-Chen
;
Lai, Fang-I
;
Lin, Gray
;
Hsiao, Ru-Shang
An InGaAs sub-monolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiberoptic applications is first time demonstrated. The active region of the device contains 3 InGaAs SML QD layers. Each of the InGaAs SML QD layer is formed by alternate deposition of InAs (< 1 ML) and GaAs. Single fundamental mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. Side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over entire current operation range. The beam profile study of the PhC-VCSEL indicates that the laser beam is well confined by the photonic crystal structure of the device. The divergence angle of the devices remains almost unchanged with increasing current. (C) 2007 Elsevier B.V. All rights reserved.
Characteristics of broad-area InGaAs submonolayer quantum-dot vertical-cavity surface-emitting lasers
(2007-10-01)
Yang, Hung-Pin D.
;
Hsu, I-Chen
;
Lai, Fang-I
;
Lin, Gray
;
Hsiao, Ru-Shang
A broad-area InGaAs submonolayer (SML) quantum-dot vertical-cavity surface-emitting laser (QD VCSEL) for fiber-optic applications is demonstrated. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (< 1 ML) and GaAs. A maximum CW output power of 12.2 mW at 30 mA has been achieved in the 990 nm range, with a threshold current of 1 mA.
Characteristics of cross-shaped polarization-switching vertical-cavity surface-emitting lasers for dual-channel communications
(2007-04-01)
Yang, Hung-Pin D.
;
Hsu, I-Chen
;
Lai, Fang-I
;
Lin, Gray
;
Kuo, Hao-Chung
The polarization switching of a cross-shaped vertical-cavity surface-emitting laser (VCSEL) for dual-channel communications is demonstrated. The polarization of the lasing output is controlled by the asymmetry in geometry of the device and direction of current injection. High output power ratio of over 5, between two orthogonal (perpendicular) polarization directions has been achieved. The lasing output of the device can be switched between two nearly orthogonal directions.
Characteristics of InGaAs submonolayer quantum-dot and InAs quantum-dot photonic-crystal vertical-cavity surface-emitting lasers
(2008-05-01)
Yang, Hung-Pin D.
;
Hsu, I. -Chen
;
Chang, Ya-Hsien
;
Lai, Fang-I
;
Yu, Hsin-Chieh
We have made InGaAs submonolayer (SML) quantum-dot (QD) and InAs QD photonic-crystal vertical-cavity surface-emitting lasers (PhC-VCSELs) for fiber-optic communications in the 990 and 1300 nm ranges, respectively. The active region of the InGaAs SML QD PhC-VCSEL contains three InGaAs SML QD layers, with each of the SML QD layer formed by alternating depositions of InAs (< 1 ML) and GaAs. The active region of the InAs QD PhC-VCSEL contains 17 undoped InAs-InGaAs QD layers. Both types of QD PhC-VCSELs exhibit single-mode characteristics throughout the current range, with side-mode suppression ratio (SMSR) larger than 35 dB. A maximum output power of 5.7 mW has been achieved for the InGaAs SML QD PhC-VCSEL. The near-field image study of the QD PhC-VCSELs indicates that the laser beam is well confined by the photonic-crystal structure of the device.
Characteristics of single-mode InGaAs sub-monolayer quantum-dot photonic-crystal VCSELs emitting in the 990 nm range
(2008)
Yang, Hung-Pin D.
;
Hsu, I. -Chen
;
Lai, Fang-I.
;
Lin, Gray
;
Hsiao, Ru-Shang
We have made InGaAs sub-monolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting lasers (QD PhC-VCSELs) for fiber-optic applications. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layer is formed by alternate deposition of InAs (< 1 ML) and GaAs. Single fundamental mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. Side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over the entire current operation range. Near-field images of the PhC-VCSELs were also measured and studied.
Characteristics of single-mode InGaAs submonolayer quantum-dot photonic-crystal vertical-cavity surface-emitting lasers
(2006-12-01)
Yang, Hung-Pin D.
;
Hsu, I-Chen
;
Lai, Fang-I
;
Lin, Gray
;
Hsiao, Ru-Shang
An InGaAs submonolayer (SML) quantum-dot photonic-crystal vertical-cavity surface-emitting laser (QD PhC-VCSEL) for fiber-optic applications is demonstrated for the first time. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layers is formed by alternate depositions of InAs (< 1 ML) and GaAs. A single-fundamental-mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. A side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over the entire current operation range. The beam profile and near-field image study of the PhC-VCSEL indicates that the laser beam,is well confined by the photonic crystal structure of the device.
Characteristics of the Fluorinated High-k Inter-Poly Dielectrics
(2010-12-01)
Hsieh, Chih-Ren
;
Chen, Yung-Yu
;
Lu, Kwung-Wen
;
Lin, Gray
;
Lou, Jen-Chung
In this letter, the reliabilities and insulating characteristics of the fluorinated aluminum oxide (Al(2)O(3)) and hafnium oxide (HfO(2)) inter-poly dielectric (IPD) are studied for the first time. Compared with the IPDs without fluorine incorporation, the results clearly indicate that fluorine incorporation process is effective to improve the insulating characteristics of both the Al(2)O(3) and HfO(2) IPDs, mainly ascribed to the trap density reduction and the smooth interface. Although HfO(2) possesses higher dielectric constant to increase the gate coupling ratio, the results apparently indicate that the fluorine incorporation process is more effective to improve the dielectric characteristics of the Al(2)O(3) IPD than the HfO(2) IPD.
Chirped multilayer quantum-dot mode-locked lasers with dual-wavelength and ground-state lasing emissions
(2019-01-01)
Chen, Yu-Chen
;
Hsieh, Pin-Hsien
;
Lin, Gray
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Monolithic passively mode-locked lasers are investigated based on chirped multi-layer InAs/InGaAs quantum-dot (QD) structure. The forward and backward tracings of light-current characteristics show two kinks and two hysteresis loops. The optical spectra reveal two lasing wavelengths around 1273 and 1230 nm, which are identified as two ground-state emissions of two differently chirped QD layers. The corresponding radio-frequency (RF) spectra of high-speed detector reveal two RF peaks at 16.21 and 16.03 GHz, which are attributed to fundamental mode-locking of two respective wavelengths. The laser pulses are confirmed by optical autocorrelator to exhibit dual-wavelength mode-locking. The pulsed characteristics of two lasing wavelengths are also discussed in terms of operating conditions. (C) 2019 Society of Photo-Optical Instrumentation Engineers (SPIE)
Continuous-Wave Lasing of 1.3-mu m Quantum-Dot Photonic-Crystal Surface-Emitting Lasers
(2018-01-01)
Hsu, Ming-Yang
;
Lin, Gray
;
Pan, Po-Chou
;
Chen, Yu-Chen
;
電子工程學系及電子研究所
Fabrication of electrically injected quantum-dot photonic-crystal (PC) surface-emitting lasers (SELs) is simplified by deposition of indium-tin-oxide over "PC slab-on-substrate" structure. Temperature-insensitive threshold current behavior is exhibited for negatively detuned PCSEL where continuous-wave lasing emission at 1308.4 nm is demonstrated for the first time.
Digitally Chirped Multilayer Quantum Dot Lasers with Dual-Wavelength Lasing Emissions
(2019-06-01)
Sun, Yi-Jan Leo
;
Hsieh, Pin-Hsien
;
Lin, Gray
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The dual-wavelength lasing emissions of digitally chirped multilayer quantum dot (QD) lasers are investigated both experimentally and theoretically. The two lasing wavelengths are both identified as ground-state (GS) emissions but originated from different stacks of QD multilayers. The lasing spectra exhibited broadening and splitting properties by injecting more current. Moreover, the wavelength-resolved light-current characteristics reveal that first GS lasing intensity upon the threshold of second GS transitions neither saturates nor droops with increasing injection current, but increases with slightly reduced slope efficiency. A theoretical model is developed for digitally chirped multilayer QD lasers. The simulation results qualitatively reproduce the experimental observations.
Dual-wavelength mode-locking of novel chirped multilayer quantum-dot lasers
(2016)
Chiang, Chun-Ping
;
Lin, Gray
;
Chen, Yu-Chen
;
Cheng, Hsu-Chieh
;
電子工程學系及電子研究所
Monolithic passively mode-locked lasers are investigated based on chirped multilayer InAs/InGaAs QDs. Three chirped wavelengths, with stacking numbers of 2, 3 and 5 layers, are designed with capped InGaAs thickness of 4, 3 and 1 nm, respectively. The ridge-waveguide devices of 5-mu m width and 3-mm length are fabricated to have absorber-to-gain length ratio of 1:9. A curve tracer is used to analyze the hysteresis on the light-current curve. Two kinks in the L-I curve are observed at threshold current near 50 mA and at higher current of about 150 mA. The lasing wavelength just above threshold is centered at 1268 nm and the RF spectrum of mode-locking is peaked at 13.32 GHz. At well above threshold of 200 mA, another RF peak at 13.21 GHz occurs that corresponds to shorter lasing wavelength around 1233 nm. The two lasing wavelengths are originated from ground-state transitions of two groups of InAs/InGaAs QDs. Simultaneous dual-wavelength mode-locking is therefore achieved at rather low forward current and low reverse bias by incorporating this novel design of QD structure.
Dynamic Characteristics and Linewidth Enhancement Factor of Quantum-Dot Vertical-Cavity Surface-Emitting Lasers
(2009-05-01)
Peng, Peng-Chun
;
Lin, Gray
;
Kuo, Hao-Chung
;
Yeh, Chao-En
;
Liu, Jui-Nung
This study explores the relative intensity noise characteristics of quantum-dot vertical-cavity surface-emitting lasers (QD VCSELs). The resonance frequency and eye diagram are presented. The linewidth enhancement factor (alpha factor) of QD VCSEL is also investigated experimentally. The values of alpha factor were measured to be between 0.48 and 0.60. Moreover, a photonic RF phase shifter is examined using the QD VCSEL. A phase shifter with a total phase shift of 2 pi was demonstrated. These investigations and demonstrations will be useful in the field of QD VCSEL.
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.
Effect of interfacial fluorination on the electrical properties of the inter-poly high-k dielectrics
(2011-06-01)
Hsieh, Chih-Ren
;
Chen, Yung-Yu
;
Lu, Kwung-Wen
;
Lin, Gray
;
Lou, Jen-Chung
In this paper, the reliabilities and insulating characteristics of the fluorinated aluminum oxide (Al(2)O(3)) and hafnium oxide (HfO(2)) inter-poly dielectric (IPD) are studied. Interface fluorine passivation has been demonstrated in terminating dangling bonds and oxygen vacancies, reducing interfacial re-oxidation and smoothing interface roughness, and diminishing trap densities. Compared with the IPDs without fluorine incorporation, the results clearly indicate that fluorine incorporation process is effective to improve the insulating characteristics of both the Al(2)O(3) and HfO(2) IPDs. Moreover, fluorine incorporation will also improve the dielectric quality of the interfacial layer. Although HfO(2) possesses higher dielectric constant to increase the gate coupling ratio, the results also demonstrate that fluorination of the Al(2)O(3) dielectric is more effective to promote the IPD characteristics than fluorination of the HfO(2) dielectric. For future stack-gate flash memory application, the fluorinated Al(2)O(3) IPD undoubtedly possesses higher potential to replace current ONO IPD than the fluorinated HfO(2) IPD due to superior insulating properties. (c) 2010 Elsevier B.V. All rights reserved.
Electrically injected 1.3-mu m quantum-dot photonic-crystal surface-emitting lasers
(2017-12-25)
Hsu, Ming-Yang
;
Lin, Gray
;
Pan, Chien-Hung
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We have fabricated electrically injected InAs/InGaAs/GaAs quantum-dot (QD) photonic-crystal (PC) surface-emitting lasers (SELs) and successfully demonstrated roomtemperature lasing emissions at 1.3-mu m wavelength for the first time. The PCSEL device fabrication was greatly simplified by deposition of transparent conducting layer of indiumtin- oxide over "PC slab-on-substrate" structure. The threshold current density per QD layer was as low as 50 A/cm(2)/layer; however, the optical output was limited to 2 mW. The bandedge lasing mode was identified and near-circular beam with narrow divergence angle less than 2 degrees was achieved. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Electrically pumped quantum dot surface emitting lasers with Bragg grating capped by ITO cladding layers
(2016)
Hong, Kuo-Bin
;
Chang, Ting-Yuan
;
Pan, Chien-Hung
;
Lin, Chien-Hung
;
Lin, Gray
QD based Bragg gratings surface emitting lasers using ITO as transparent cladding layers were demonstrated. Measured lasing peak locates at 1298nm and threshold current density of 210 A/cm(2). The laser shows extremely small divergence surface-emitted beam and thermal redshift of 0.08 nm/K in peak wavelength.
Enhanced data retention characteristic on SOHOS-type nonvolatile flash memory with CF4-plasma-induced deep electron trap level
(2011)
Hsieh, Chih-Ren
;
Chen, Yung-Yu
;
Lin, Wen-Shin
;
Lin, Gray
;
Lou, Jen-Chung
The improved data retention characteristics of Polysilicon-oxide-hafnium oxide-oxide-silicon (SOHOS) type nonvolatile memory were obtained by post-HfO2 trapping layer deposition tetrafluoromethane (CF4) plasma treatment. The memory characteristics such as program/erase speed, retention and endurance were studied comprehensively. That fluorine atoms incorporated into Hf-based high-k material eliminate shallow trap defect level effectively and remain deeper trap level. Although the shallow traps of the HfOF trapping layer SOHOS memory have passivated, it doesn't deteriorate the program/erase speed obviously and retention characteristic was then improved because of deeper electron storage level. The results clearly indicate CF4 plasma treatment-induced deep electron storage level is a feasible technology for future SOHOS-type nonvolatile flash memory application.
Highly strained InGaAs/GaAs quantum well vertical-cavity surface-emitting lasers
(2007-06-01)
Yang, Hung-Pin D.
;
Chen, I-Liang
;
Lee, Chen-Hong
;
Chiou, Chih-Hong
;
Lee, Tsin-Dong
We report our results on the highly strained InGaAs/GaAs quantum well (QW) vertical-cavity surface-emitting lasers (VCSELs) in the 1140 to 1250 nm range. The epitaxial structures were grown on (100)GaAs substrates by metal-organic chemical vapor deposition (MOCVD). A maximum output power of more than 6.3 mW has been demonstrated. The spectral characteristics were also measured and analyzed.