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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Functional Mapping for Passively Mode-Locked Semiconductor Lasers
摘要： Passive Mode-locking (PML) of semiconductor lasers is a most promising method for the generation of low repetition rate picosecond pulses, which is of paramount importance for a number of applications. Because of the long round-trip times and fast time scales of the ?eld evolution this regime is computationally very intensive. Studying the pulse train dynamics and temporal jitter can require simulations over hundreds of thousands of round-trips. If, in addition to the longitudinal dynamics, transverse diffraction of the beam or thermal processes are considered, the problem becomes intractable. The Haus master equation [1] is a widely used approach to study PML. By considering a partial differential equation (PDE) model one can restrict the analysis of the ?eld to a small temporal interval around the pulse, making the approach computationally ef?cient. Yet this method, when applied to a particular design, provides only qualitative predictions due to the many simplifying hypothesis involved. We present a method that combines the accuracy of ?rst principle time-delayed models with the computational ef?ciency of the Haus master equation. Our method is based upon computing only the so-called fast stage in the vicinity of the pulse where stimulated emission is dominant, while using an approximate analytical solution of the dynamics during the slow stages in-between pulses. We illustrate the idea of the functional mapping (FM) using the DDE model of [2] that considers unidirectional propagation in a ring laser, however it can be used in other models as well, including approaches using delay algebraic equations (DAEs) like [3]. The equations for the ?eld amplitude A, the gain G and the absorption Q read ˙A γ = ?A +Y (t ? τ) , ˙Q = Q0 ? Q ? s (cid:2) 1 ? e (cid:3) ?Q |A|2 , (1) (3) ˙G = Γ (G0 ? G) ? e ?Q (cid:2) eG ? 1 (cid:3) |A|2 , (2) (cid:4) Y (t) = √ κ exp 1 ? iα 2 G (t) ? 1 ? iβ 2 (cid:5) Q (t) A (t) . (4) We wrote Eq. (1) in a form that makes apparent that the forcing ?eld Y (t ? τ) de?ned in Eq. (4) is a nonlinear function that is known over a whole interval of duration τ. Since gain G and losses Q are functions of A, Y involves only the past values of the ?eld, i.e., Y (t ? τ) = g [A (t ? τ)]. Knowing the forcing term Y, Eq. (1) can be solved for A over an interval of duration τ. Integrating Eqs. (1-4), not over the whole round-trips, but only in a selected time interval in the pulse vicinity, is at the core of the functional mapping (FM) method. The speedup of the FM is equal to the ratio of the actual integration domain 2δ and of the full round-trip τ, i.e., m = τ/ (2δ ). Taking a domain of duration 2δ = 5τp, a pulse with of τp = 1 ps at a repetition rate of τ ?1 = 1 GHz, yields a speedup m = 200, i.e., a 24 hours simulation with, e.g., slow thermal effects or transverse diffraction could potentially be achieved in a few (～ 7) minutes.
关键词： picosecond pulses,semiconductor lasers,Passive Mode-locking,computational efficiency,functional mapping
更新于2025-09-11 14:15:04
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Modulation Performance Comparison of Quantum-Dot and Quantum-Well Lasers Under External Feedback
摘要： Modulation performance of a quantum-dot and a quantum-well laser under external optical feedback were experimentally compared at a modulation speed of 10 Gbps. The quantum-dot laser showed much better performance under optical feedback.
关键词： Semiconductor lasers,Quantum well,Quantum dot
更新于2025-09-11 14:15:04
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Numerical and Experimental Analysis of Optical Frequency Comb Generation in Gain-Switched Semiconductor Lasers
摘要： We have performed a systematic experimental and simulation analysis of the optical frequency combs generated by gain-switching single mode laser diodes, either free-running or subjected to optical injection. The simulations have been produced with a dynamical model consisting of three rate equations that include stochastic noise terms. The model parameters have been extracted from experiments. An exhaustive comparison between the simulated and the experimental temporal profiles and optical spectra generated under a wide range of switching and optical injection conditions has been performed. The excellent quantitative agreement found in the entire range of the explored operating conditions supports the validity of the model for the analysis of the comb generation mechanisms. The detailed maps generated provide guidelines for selecting suitable operating conditions for specific comb characteristics.
关键词： optical frequency combs,Semiconductor lasers,rate equations,optical injection,gain switching
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Karbala City, Iraq (27–28 March 2019)] THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Crisis roots of quantum dot semiconductor lasers with positive and negative optoelectronics feedback
摘要： The chaos feedback technique in semiconductor lasers is important for many applications in various fields such as communication and medicine. In this study, positive and negative optoelectronic feedback techniques (OPF) were utilized to study the behavior of quantum dot semiconductor lasers (QDSL), at a single value of the optoelectronics feedback strength (0.2) and (-0.2). The adopted delay times ranged from 100 to 240 ps, with steps of 10 ps. The results showed high-stability periods at certain times and chaotic periods or high disturbance at others. Besides that, crisis roots were found in all values of the delay times for positive and negative feedback. Further, the results showed no similarities except for delay time of 110 ps for positive and negative optoelectronic feedback.
关键词： optoelectronic feedback,crisis roots,chaos feedback technique,quantum dot semiconductor lasers,stability periods
更新于2025-09-11 14:15:04
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - 55 Gbps error free data transmission with 980 nm VCSELs across 100 m of multiple-mode optical fiber
摘要： Data transmission at 55 Gbps is achieved across 100 meters of optical fiber with a bit error ratio below 1E-12 with 980 nm single cavity oxide aperture diameter vertical cavity surface emitting lasers.
关键词： Semiconductor lasers,Advanced Active Devices,Quantum well,quantum dot and nano-structured photonic devices
更新于2025-09-11 14:15:04
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Applied Nanophotonics || Stimulated emission and lasing
摘要： Stimulated transitions in quantum systems represent the principal background for laser operation. Lasers play important roles in daily life and form a valuable part of photonics. Though the first lasers were supposed to have an impact on material processing owing to extreme energy concentration, currently the main applications of lasers are not based on high-energy abilities, but essentially on their compactness, cheapness, and efficiency. Optical communication, laser printers, and DVD players are the most common laser applications, and here semiconductor lasers are definitely unsurpassed. In this chapter we provide a brief introduction to the principles of laser operation and laser device engineering to emphasize where nanostructures can be useful and which components of lasers can be improved by means of nanophotonic solutions. Because of the scope of this book, a brief explanatory style is used which may confuse laser experts but at the same time may still appear complicated for newcomers. This chapter may appear complicated for readers not at all familiar with lasers, and in this case appropriate textbooks are suggested for further reading.
关键词： quantum systems,lasing,stimulated emission,optical gain,semiconductor lasers
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Time-modulated Periodic Systems with PT Symmetry
摘要： This work explores the effects of parity-time (PT) symmetry in time-modulated periodic systems. Mechanisms for dynamic tunability of exceptional points are presented. We show that synthetic linear momentum imparted by time-modulation leads to uni-directional exceptional points. Such structures could see application in uni-directional lasers with tunable directionality.
关键词： semiconductor lasers,photonic crystals,distributed feedback lasers,time-varying circuits,parity-time symmetry,time-varying systems,optical modulation
更新于2025-09-04 15:30:14
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Comparison of Optical Single Sideband Techniques for THz-over-fiber Systems
摘要： The use of single sideband (SSB) signals and envelope detection is a promising approach to enable the use of economic free-running lasers in photonic THz communications. To combat the signal-signal beat interference (SSBI) associated with envelope detection, broad guard bands (GBs) may be used given the large unregulated spectrum available at THz frequencies (100 GHz – 10 THz). In this scenario, the conventional way of generating SSB signals through a digital SSB filter (here referred to as the CSSB scheme) would require quite high analog digital-to-analog converter (DAC) bandwidths. Digital virtual SSB (DVSSB) and analog virtual SSB (AVSSB) have been proposed in direct-detection optical systems for relaxing the DAC bandwidth requirements. In this paper, we compare the three techniques through simulations and implement them, for the first time, in a THz-over-fiber (ToF) system operating at 250 GHz. For the transmission experiments we employ 5 GBd 16-QAM signals with three different GBs (5.5 GHz, 4.75 GHz and 3.5 GHz). The simulations show that the best performance is obtained with the AVSSB technique, while the worst is obtained with the DVSSB scheme, where the quality of the generated sideband degrades with carrier-to-sideband power ratio. In the experimental transmissions, where receiver noise was the main source of noise, similar behavior was found between the three techniques. At the 3.5 GHz GB, however, the DVSSB exhibited a penalty of 1 dB with respect to the other two. This is likely to be due to nonlinear distortions caused by the increase in the virtual tone power.
关键词： microwave photonics,Broadband communication,semiconductor lasers,photonic integrated circuits,digital signal processing,envelope detectors,optical mixing,millimeter wave communication
更新于2025-09-04 15:30:14