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High Speed Directly Modulated Fabry-Perot Lasers With an Ultra-Short Cavity Length
(2020-05-01)
Tsai, Yi-Lin
;
Wang, Shou-Wei
;
Huang, Huang-Hsiung
;
Shih, Hsiang-Yun
;
Lu, Po-Yen
In this study, Fabry-Perot quantum well lasers with shortened cavity designs (25 and 50 mu m) were fabricated. The devices had dry-etched and cleaved facets and exhibited an output power of up to 2.36 mW for a cavity length of 25 mu m; good spectral performance was achieved. Single-optical-mode operation with better than 25dB of side mode suppression ratio can be achieved for the fabricated devices with 25- and 50-mu m cavities. The short-cavity devices also exhibited highspeed modulation at elevated temperatures. Moreover, 25 Gb/s eye diagrams could be obtained at 65oC for the 25 mu m device and 55oC for the 50 mu m device. Due to their small area, ultra-shortcavity Fabry-Perot laser can be suitably used in next-generation light sources for optical communication.
Generating High-Order Transverse Patterns in Optically Pumped Semiconductor Lasers
(2019-11-01)
Tuan, Pi-Hui
;
Hsieh, Yen-Hui
;
Tu, Chin-Wei
;
Lee, Chi-Chun
;
Tsou, Chia-Han
High-order pattern formation in an optically pumped semiconductor laser (OPSL) under a selective pumping with varying spatial overlap between the pump beam and transverse modes is explored. In contrast to transverse pattern generation by off-axis pumped solid-state lasers where the mode order can be flexibly increased, experimental results reveal that the selective pumping fails to realize high-order mode operation in OPSLs when the pump-to-mode size ratio and pump power are insufficiently large. On the other hand, several high-order patterns belonging to the Hermite-Laguerre-Gaussian (HLG) modes are observed when scanning a large-ratio pump beam to specific positions on the gain chip. These HLG modes are experimentally confirmed to mainly originate from the transverse non-uniformity of present OPSL chip, while their structural features cannot be simply correlated with the pump scanning positions. Nevertheless, it is believed that the first-time observation of pure HLG modes under the large-ratio pumping can offer useful insights into the high-order pattern manipulation in OPSLs.
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.
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.
Theoretical analysis of 630-nm band GaInP-AlGaInP strained quantum-well lasers considering continuum states
(1997-03-01)
Yen, ST
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
GaInP-AlGaInP strained quantum-well lasers with emission wavelength at 630-nm band are theoretically analyzed in detail and then optimized, The valence band structure of quantum wells is obtained by evaluating the 6x6 Luttinger-Kohn Hamiltonian including the coupling among the heavy hole, the light hole, and the spin-orbital split-off hole bands, The effect of optical transition from/to continuum states not confined to the quantum well is studied, It is found that the optical transition from/to the continuum states is serious as the band gap of the confining layers is close to the quasi-Fermi level separation, leading to considerable radiative current, This radiative current is undesirable since the corresponding optical transition does not contribute significantly to the threshold gain, The gain-radiative current characteristic is therefore poor for confining layers containing a low Al content. To avoid unreasonable gain/absorption, the non-Markovian convolution lineshape is used instead of the conventional Lorentzian lineshape. The leakage current is high for single quantum-well lasers with wide bandgap confining layers, It can be reduced by increasing the quantum-well number, the dopant concentration, and the band gap of cladding layers, The calculated threshold current agrees wed with the observation, The band gap shrinkage due to the carrier-carrier interaction is considered to obtain an emission wavelength consistent with the experimental result.
Simulation of 1300-nm In0.4Ga0.6As0.986N0.014/GaAs1-xNx quantum-well lasers with various GaAs1-xNx strain compensated barriers
(2004-11-01)
Chang, YA
;
Kuo, HC
;
Chang, YH
;
Wang, SC
;
光電工程學系
In this article, the laser performance of the 1300-nm In0.4Ga0.6As0.986N0.014/GaAs1 - xNx quantum-well (QW) lasers with various GaAs1 - xNx strain compensated barriers (x = 0%, 0.5%, 1%, and 2%) has been numerically investigated with a laser technology integrated simulation program. The simulation results suggest that with x = 0% and 0.5% can have better optical gain properties and high characteristic temperature coefficient To values of 110 and 94 K at the temperature range of 300-370 K. As the nitrogen composition in GaAs1 - xNx barrier increases more than 1% the laser performance degrades rapidly and the To value decreases to 87 K at temperature range of 300-340 K. This can be attributed to the decrease of conduction band carrier confinement potential between In0.4Ga0.6As0.986N0.014 QW and GaAs1 - xNx barrier and the increase of electronic leakage current. Finally, the temperature dependent electronic leakage current in the InGaAsN/GaAs1 - xNx quantum-well lasers are also investigated. (C) 2004 Elsevier B.V. All rights reserved.
Novel chirped multilayer quantum-dot lasers
(2008-01-01)
Lin, G.
;
Chang, C. Y.
;
Tseng, W. C.
;
Lee, C. P.
;
Lin, K. F.
Chirped multilayer (N=10) QD lasers with 2-, 3- and 5-layer of longer-, medium-, and shorter-wavelength QD stacks, respectively, were grown in this work. Low threshold current density and high saturated modal gain were achieved in this specially designed QD structure. Empirical gain-current analysis was performed on this chirped multilayer QD structure for the first time. It was consistent with our spectral observations and provided valuable information on carrier recombination in chirped multilayer QD structure. Two novel spectral characteristics were discovered also for the first time. First, simultaneous two-wavelength lasing around threshold was observed under particular gain-loss condition at this specific multilayer structure of QD stacking numbers. Second, at cryogenic temperature, simultaneous two-wavelength lasing emissions switched from longer-wavelength lasing first to shorter-wavelength lasing first with increasing current injection. Non-uniform carrier distribution among chirped multilayer QD structure is evident at low temperature below 200 K from our analysis.
Photonic Crystal Surface Emitting Lasers with InAs/InGaAs/GaAs Quantum Dots
(2017-01-01)
Chen, Tzu-Shan
;
Lee, Zong-Lin
;
Hsu, Ming-Yang
;
Lin, Gray
;
Lin, Sheng-Di
InAs/InGaAs/GaAs quantum-dot (QD) photonic crystal (PC) surface emitting lasers were fabricated and room-temperature lasing emissions were demonstrated by optical pumping for the first time. The etch depth of PC holes is the critical parameter for adjacent diffraction coupling between PC structure and QD gain media.
850 nm Vertical-Cavity Surface-Emitting Laser Arrays With Enhanced High-Speed Transmission Performance Over a Standard Multimode Fiber
(2017-08-01)
Yen, Jia-Liang
;
Chen, Xin-Nan
;
Chi, Kai-Lun
;
Chen, Jason
;
Shi, Jin-Wei
The functionality of novel parallel and series highspeed vertical-cavity surface-emitting laser (VCSEL) arrays, which can greatly relax the tradeoff between output power and modulation speed, is demonstrated. Both types of array structure allow improvement in the output power with no degradation in their maximum modulation speed as compared to a single reference unit. The observed invariant electrical-optical bandwidth shown for these array structures is mainly due to the effective reduction of the differential resistance and parasitic capacitance, arising from the Zn-diffusion and oxide-relief apertures fabricated in the VCSEL unit. This in turn minimizes the degradation in the RC-limited bandwidth with the VCSEL arrays. Furthermore, the dense packing of single VCSELs, with Zn-diffusion apertures for optical mode control, minimizes the coupling loss between the output from the array into a standard multimode fiber (MMF). Compared with the single VCSEL unit, the parallel VCSEL array shows a significant enhancement in transmission performance over a standard OM4 MMF, which includes a larger eye margin, a higher signal-to-noise ratio, as well as a higher error-free data rate (48 versus 44 Gbit/sec). The device modeling technique is used to perform device analysis. From the results we can conclude that the improvement with the parallel array is because the value of the internal impedance is closer to the 50-Omega signal source, which minimizes the microwave reflection induced timing jitter in the eye-patterns.

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