Browsing by Author "Cheng, Hsu-Chieh"

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Analysis of Relative Intensity Noise Spectra for Uniformly and Chirpily Stacked InAs-InGaAs-GaAs Quantum Dot Lasers
(2012-02-01)
Lin, Gray
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Tang, Hao-Ling
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Cheng, Hsu-Chieh
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Chen, Hung-Lin
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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).
Dual-wavelength mode-locking of novel chirped multilayer quantum-dot lasers
(2016)
Chiang, Chun-Ping
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Lin, Gray
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Chen, Yu-Chen
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Cheng, Hsu-Chieh
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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.
Investigation of quantum dot passively mode-locked lasers with excited-state transition
(2013-11-04)
Cheng, Hsu-Chieh
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Lee, Chien-Ping
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Monolithic passively mode-locked quantum dot lasers with excited-state transition were investigated in a broad operating range without ground-state lasing. Optical and electrical characteristics of these mode locked lasers were studied in detail at different levels of injection current and absorber bias. Very different behaviors in the evolution of the hysteresis, the optical spectra and the evolution of repetition frequency were observed between our lasers and conventional quantum dot lasers with ground-state transition. Possible mechanisms behind these observed phenomena were proposed and discussed. A minimum pulse width of 3.3 ps and an externally compressed pulse width of 0.78 ps were obtained. (C) 2013 Optical Society of America
Low threshold current and widely tunable external cavity lasers with chirped multilayer InAs/InGaAs/GaAs quantum-dot structure
(2012-02-13)
Lin, Gray
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Su, Pei-Yin
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Cheng, Hsu-Chieh
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Low threshold and widely tunable InAs/GaAs quantum-dot lasers are implemented with grating-coupled external-cavity arrangement. Throughout the tuning range of 130 nm, from 1160 to 1290 nm, the threshold current density is not more than 0.9 kA/cm(2) and no noticeable threshold jump is observed. For a shorter-cavity device, the injection current is kept at a record low value of 90 mA but the tuning range is further extended to 150 nm, from 1143 to 1293 nm. The effect of cavity length on the tuning characteristics is discussed and the strategy for design and optimization of multilayer quantum-dot structure is also proposed. (C) 2012 Optical Society of America
Wavelength switching transition in quantum dot lasers
(2007-02-19)
Wang, Hsing-Yeh
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Cheng, Hsu-Chieh
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Lin, Sheng-Di
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Lee, Chien-Ping
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電子工程學系及電子研究所
Control and the selection of the ground state emission and/or the excited state emission of an InAs quantum dot laser have been demonstrated. By controlling the currents injected into each section of a two-section cavity, switching between the ground state emission and the excited state emission with a separation of 100 nm was achieved. With a constant total current, either ground state lasing (similar to 1.3 mu m), excited state lasing (similar to 1.2 mu m), or dual state lasing can be obtained simply by adjusting the current ratio between the two sections. (c) 2007 American Institute of Physics.