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Search Results (6)

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Keywords = linewidth enhancement factor (LEF)

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11 pages, 2910 KB  
Communication
Theoretical Study on Low-Chirp Directly Modulated DFB Lasers with (110)-Oriented Quantum Well
by Jianwei Li, Mengzhu Hu, Xinyang Su, Yanting Liu and Ke Zhan
Photonics 2025, 12(7), 647; https://doi.org/10.3390/photonics12070647 - 25 Jun 2025
Viewed by 561
Abstract
The low-chirp operation of distributed feedback lasers is highly desirable in high-speed and high-bit rate optical transmission. In this article, we address this issue by theoretically investigating the possibility of further a reduction in the linewidth enhancement factor (LEF) of a quantum well [...] Read more.
The low-chirp operation of distributed feedback lasers is highly desirable in high-speed and high-bit rate optical transmission. In this article, we address this issue by theoretically investigating the possibility of further a reduction in the linewidth enhancement factor (LEF) of a quantum well (QW). The energy band structure of AlGaInAs quantum-well DFB lasers grown with a (110) crystal orientation in the active region of the L-band has been theoretically analyzed using multi-band k.p perturbation theory, by reducing the asymmetry of conduction bands and valence bands and thus the linewidth enhancement factor parameter, which is related to the frequency chirp. Simulation results show that the LEF of the directly modulated DFB laser is reduced from 2.434 to 1.408 by designing the (110)-oriented compression-strained Al0.06Ga0.24InAs multiple-quantum-well structure, and the eye diagram of the (110)-oriented quantum-well DFB laser with a digital signal transmission of 20 km is significantly better than the (001) crystal-oriented quantum-well DFB laser for the 10Gbps optical fiber communication system, thus achieving a longer distance and higher-quality optical signal transmission. Full article
(This article belongs to the Section Optoelectronics and Optical Materials)
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12 pages, 2799 KB  
Article
Dynamics of Semiconductor Laser Subject to Optical Feedback with Linewidth Enhancement Factor and Spontaneous Emission Factor
by Salah Abdulrhmann and Jabir Hakami
Appl. Sci. 2023, 13(24), 13099; https://doi.org/10.3390/app132413099 - 8 Dec 2023
Viewed by 1654
Abstract
In this article, the dependence of the operation states, dynamics, and noise of laser diodes (LD) with external optical feedback (OFB) on the linewidth enhancement factor (LEF) and spontaneous emission factor (SEF) have been investigated. We systematically studied the classification of the laser [...] Read more.
In this article, the dependence of the operation states, dynamics, and noise of laser diodes (LD) with external optical feedback (OFB) on the linewidth enhancement factor (LEF) and spontaneous emission factor (SEF) have been investigated. We systematically studied the classification of the laser dynamics based on the bifurcation diagrams (BDs) of the photon numbers and the relative intensity noise (RIN) spectra at different levels of OFB, LEF, and SEF. The simulation results show that variations in the LEF and SEF lead to significant changes in the laser operation states and dynamics, which vary from continuous wave (CW), pulsation, and chaos states. The Hopf bifurcation (HB) point moves toward increasing/decreasing OFB intensity by increasing/decreasing the SEF/LEF. The laser state becomes more stable through a wide range of OFB by increasing/decreasing the SEF/LEF. The RIN reduces the solitary laser noise level at higher/lower values of SEF/LEF when the laser is operated under OFB. The relaxation frequency of the laser shifts toward higher values by increasing/decreasing the SEF/LEF through most laser states, and the RIN peak is higher than solitary laser noise by four orders of magnitude, especially in the pulsation regions. In the low-frequency region, the RIN is enhanced from one to two orders by reducing the LEF and SEF through laser states. Full article
(This article belongs to the Section Optics and Lasers)
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6 pages, 2674 KB  
Article
Frequency Pulling and the Linewidth Enhancement Factor in Optically Injected Semiconductor Laser
by Najm M. Al-Hosiny
Photonics 2022, 9(11), 866; https://doi.org/10.3390/photonics9110866 - 17 Nov 2022
Cited by 2 | Viewed by 2350
Abstract
The effect of the linewidth enhancement factor (LEF) on the frequency pulling behavior in optically injected lasers is theoretically investigated. The frequency pulling is found to be exponentially dependent on the LEF. This dependence is systematically revealed and explained. Full article
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12 pages, 4375 KB  
Article
Nonlinear Dynamics of Interband Cascade Laser Subjected to Optical Feedback
by Hong Han, Xumin Cheng, Zhiwei Jia and K. Alan Shore
Photonics 2021, 8(9), 366; https://doi.org/10.3390/photonics8090366 - 31 Aug 2021
Cited by 11 | Viewed by 3367
Abstract
We present a theoretical study of the nonlinear dynamics of a long external cavity delayed optical feedback-induced interband cascade laser (ICL). Using the modified Lang–Kobayashi equations, we numerically investigate the effects of some key parameters on the first Hopf bifurcation point of ICL [...] Read more.
We present a theoretical study of the nonlinear dynamics of a long external cavity delayed optical feedback-induced interband cascade laser (ICL). Using the modified Lang–Kobayashi equations, we numerically investigate the effects of some key parameters on the first Hopf bifurcation point of ICL with optical feedback, such as the delay time (τf), pump current (I), linewidth enhancement factor (LEF), stage number (m) and feedback strength (fext). It is found that compared with τf, I, LEF and m have a significant effect on the stability of the ICL. Additionally, our results show that an ICL with few stage numbers subjected to external cavity optical feedback is more susceptible to exhibiting chaos. The chaos bandwidth dependences on m, I and fext are investigated, and 8 GHz bandwidth mid-infrared chaos is observed. Full article
(This article belongs to the Special Issue Nonlinear Dynamics of Semiconductor Lasers and Their Applications)
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11 pages, 3036 KB  
Article
Nonlinear Dynamics of Two-State Quantum Dot Lasers under Optical Feedback
by Xiang-Hui Wang, Zheng-Mao Wu, Zai-Fu Jiang and Guang-Qiong Xia
Photonics 2021, 8(8), 300; https://doi.org/10.3390/photonics8080300 - 27 Jul 2021
Cited by 4 | Viewed by 2572
Abstract
A modified rate equation model was presented to theoretically investigate the nonlinear dynamics of solitary two-state quantum dot lasers (TSQDLs) under optical feedback. The simulated results showed that, for a TSQDL biased at a relatively high current, the ground-state (GS) and excited-state (ES) [...] Read more.
A modified rate equation model was presented to theoretically investigate the nonlinear dynamics of solitary two-state quantum dot lasers (TSQDLs) under optical feedback. The simulated results showed that, for a TSQDL biased at a relatively high current, the ground-state (GS) and excited-state (ES) lasing of the TSQDL can be stimulated simultaneously. After introducing optical feedback, both GS lasing and ES lasing can exhibit rich nonlinear dynamic states including steady state (S), period one (P1), period two (P2), multi-period (MP), and chaotic (C) state under different feedback strength and phase offset, respectively, and the dynamic states for the two lasing types are always identical. Furthermore, the influences of the linewidth enhancement factor (LEF) on the nonlinear dynamical state distribution of TSQDLs in the parameter space of feedback strength and phase offset were also analyzed. For a TSQDL with a larger LEF, much more dynamical states can be observed, and the parameter regions for two lasing types operating at chaotic state are widened after introducing optical feedback. Full article
(This article belongs to the Special Issue Nonlinear Dynamics of Semiconductor Lasers and Their Applications)
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11 pages, 2625 KB  
Article
Nonlinear Dynamics of Exclusive Excited-State Emission Quantum Dot Lasers Under Optical Injection
by Zai-Fu Jiang, Zheng-Mao Wu, Elumalai Jayaprasath, Wen-Yan Yang, Chun-Xia Hu and Guang-Qiong Xia
Photonics 2019, 6(2), 58; https://doi.org/10.3390/photonics6020058 - 27 May 2019
Cited by 19 | Viewed by 3956
Abstract
We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period [...] Read more.
We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period one (P1), period two (P2), multi-period (MP), and chaotic pulsation (CP). Through mapping these dynamic states in the parameter space of the frequency detuning and the injection coefficient, it can be found that the IL occupies a wide region and the dynamic evolution routes appear in multiple forms. Via permutation entropy (PE) calculation to quantify the complexity of the CP state, the parameter range for acquiring the chaos with high complexity can be determined. Moreover, the influence of the linewidth enhancement factor (LEF) on the dynamical state of the ES-QD laser is analyzed. With the increase of the LEF value, the chaotic area shrinks (expands) in the negative (positive) frequency detuning region, and the IL region gradually shifts towards the negative frequency detuning. Full article
(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)
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