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- 摘要
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- 实验方案
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2a??10???μm Mida??Infrared Fibera??Based Supercontinuum Laser Source: Experiment and Simulation
摘要： Mid-infrared supercontinuum (mid-IR SC) sources in the 2–20 μm molecular fingerprint region are in high demand for a wide range of applications including optical coherence tomography, remote sensing, molecular spectroscopy, and hyperspectral imaging. Herein, mid-IR SC generation is investigated in a cascaded silica-ZBLAN-chalcogenide fiber system directly pumped with a commercially available pulsed fiber laser operating in the telecommunications window at 1.55 μm. This fiber-based system is shown to generate a flat broadband mid-IR SC covering the entire range from 2 to 10 μm with several tens of mW of output power. This technique paves the way for low cost, practical, and robust broadband SC sources in the mid-IR without the requirement of mid-infrared pump sources or Thulium-doped fiber amplifiers. A fully realistic numerical model used to simulate the nonlinear pulse propagation through the cascaded fiber system is also described and the numerical results are used to discuss the physical processes underlying the spectral broadening in the cascaded system. Finally, recommendations are provided for optimizing the current cascaded system based on the simulation results.
关键词： soft-glass fibers,nonlinear optics and solitons,supercontinuum generation,chalcogenide fibers,fiber lasers,ZBLAN fibers
更新于2025-09-23 15:21:01
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SBS pulse compression using bulk fused silica by diode-pumped solid-state lasers at 1??kHz repetition rate
摘要： This study is focused on constructing a highly stable diode-pumped solid-state laser system by conducting experiments on high-repetition-rate SBS pulse compression using bulk fused silica. A multi-rod serial-connection structure is adopted for SBS expriments by comparing K8 glass and fused silica medium at a 10 Hz repetition rate. The optimized structure is obtained according to variation of the pump power density. Based on the optimized structure, fused silica-based SBS pulse compression is carried out in the range of 100–1000 Hz and the parameter performance of laser system after compression is also evaluated by comparing a HT270 liquid medium. Experimental results indicate that the energy e?ciency of fused silica-based SBS is improved by approximately 40% compared with that of K8 glass. Further, the energy relative standard deviation of fused silica-based SBS is reduced by approximately 88% compared with HT270 medium, indicating that bulk fused silica is advantageous for high-repetition-rate SBS pulse compression because of its un-?uidity, high thermal conductivity and power-load ability. In addition, a 1 kHz highly-stable sub-nanosecond compressed pulse is achieved using bulk fused silica medium at a pump energy of 50 mJ. Furthermore, the SBS energy e?ciency can be further improved by increasing the input energy.
关键词： Pulse compression,High repetition rate,Solid-state lasers,Sub-nanosecond pulse,Stimulated Brillouin scattering (SBS)
更新于2025-09-23 15:21:01
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Numerical model for small-signal modulation response in vertical-cavity surface-emitting lasers
摘要： We present a numerical model allowing for simulations of small-signal modulation (SSM) response of vertical-cavity surface-emitting lasers (VCSELs). The model of SSM response utilizes only the data provided by a static model of continuous-wave (CW) operation for a given bias voltage. Thus the fitting of dynamic measurement parameters is not needed nor used. The validity of this model has been verified by comparing experimental SSM characteristics of a VCSEL with the results of simulations. A good agreement between experiment and simulations has been observed. Based on the results obtained in the simulations of the existing laser, the impact of the number of quantum wells in the active region on the modulation properties has been calculated and analyzed.
关键词： optical data transfer,numerical modeling,semiconductor lasers,small-signal modulation response
更新于2025-09-23 15:21:01
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Ultrafast response of harmonic modelocked THz lasers
摘要： The use of fundamental modelocking to generate short terahertz (THz) pulses and THz frequency combs from semiconductor lasers has become a routine affair, using quantum cascade lasers (QCLs) as a gain medium. However, unlike classic laser diodes, no demonstrations of harmonic modelocking, active or passive, have been shown in THz QCLs, where multiple pulses per round trip are generated when the laser is modulated at the harmonics of the cavity’s fundamental round-trip frequency. Here, using time-resolved THz techniques, we show for the ?rst time harmonic injection and mode-locking in which THz QCLs are modulated at the harmonics of the round-trip frequency. We demonstrate the generation of the harmonic electrical beatnote within a QCL, its injection locking to an active modulation and its direct translation to harmonic pulse generation using the unique ultrafast nature of our approach. Finally, we show indications of self-starting harmonic emission, i.e., without external modulation, where the QCL operates exclusively on a harmonic (up to its 15th harmonic) of the round-trip frequency. This behaviour is supported by time-resolved simulations of induced gain and loss in the system and shows the importance of the electronic, as well as photonic, nature of QCLs. These results open up the prospect of passive harmonic modelocking and THz pulse generation, as well as the generation of low-noise microwave generation in the hundreds of GHz region.
关键词： harmonic modelocking,ultrafast response,THz QCLs,terahertz pulses,quantum cascade lasers
更新于2025-09-23 15:21:01
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Saturable plasmonic metasurfaces for laser mode locking
摘要： Metamaterials are artificial materials made of subwavelength elementary cells that give rise to unexpected wave properties that do not exist naturally. However, these properties are generally achieved due to 3D patterning, which is hardly feasible at short wavelengths in the visible and near-infrared regions targeted by most photonic applications. To overcome this limitation, metasurfaces, which are the 2D counterparts of metamaterials, have emerged as promising platforms that are compatible with planar nanotechnologies and thus mass production, which platforms the properties of a metamaterial into a 2D sheet. In the linear regime, wavefront manipulation for lensing, holography, and polarization control has been achieved recently. Interest in metasurfaces operating in the nonlinear regime has also increased due to the ability of metasurfaces to efficiently convert incident light into harmonic frequencies with unusual polarization properties. However, to date, the nonlinear absorption of metasurfaces has been mostly ignored. Here, we demonstrate that plasmonic metasurfaces behave as saturable absorbers with modulation performances superior to the modulation performance of other 2D materials and exhibit unusual polarimetric nonlinear transfer functions. We quantify the link between saturable absorption, the plasmonic resonances of the unit cell and their distribution in a 2D metasurface, and finally provide a practical implementation by integrating the metasurfaces into a fiber laser cavity operating in pulsed regimes driven by the metasurface properties. As such, this work provides new perspectives on ultrathin nonlinear saturable absorbers for applications where tunable nonlinear transfer functions are needed, such as in ultrafast lasers or neuromorphic circuits.
关键词： fiber lasers,metamaterials,plasmonic,saturable absorbers,metasurfaces,nonlinear optics
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO?? 2017: 36th International Congress on Applications of Lasers & Electro-Optics - Atlanta, Georgia, USA (October 22a??26, 2017)] International Congress on Applications of Lasers & Electro-Optics - Transformation of Gaussian beams into M-beams for advanced microvia drilling
摘要： Typical laser systems produce Gaussian laser beams that may not be suitable for high precision materials processing. This study considers laser microvia drilling of multilayer polymeric substrates for high density interconnects of microelectronics devices. Closely spaced microvias reduce the interconnect distance between the processors to meet the ever increasing demand for transferring large volumes of data at high rates. CO2 lasers of 9.3 μm wavelength is commonly used for drilling microvias in current polymeric substrates because of their higher absorption coefficient at this wavelength than at 10.6 μm wavelength of conventional CO2 lasers. High absorption coefficient provides a volumetric heating mechanism of shallow depth to enable surface-controlled vaporization of the polymeric materials. Gaussian or top-hat laser beams generally leave carbonized polymeric residue at the bottom corner and on the side wall of the microvias, and this residue hinders the subsequent microsoldering of electronic devices to the interconnects. The formation of the residue can be reduced using M-beams for microvia drilling. A thermal model is developed to determine the intensity distribution of the M-beam. To achieve this M-beam from a Gaussian beam, a lens system is designed using the Fresnel diffraction model. Drilling experiments have been conducted using an M-beam and the shape and size of the microvia are found to match the theoretical predictions very well.
关键词： microvia drilling,high density interconnects,Gaussian beams,CO2 lasers,M-beams,polymeric substrates
更新于2025-09-23 15:21:01
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Optical Waveform Tailoring in Passive and Laser Cavity Fibre Systems
摘要： The interplay among the effects of dispersion, nonlinearity and gain/loss in optical fibres is a powerful tool to generate a broad range of pulse shapes with tuneable properties. Here we propose a method to optimise the systems parameters for a given pulse target. By reducing the system complexity and applying machine-learning strategies, we show that it is possible to efficiently identify the sets of parameters of interest. Two configurations are numerically investigated: pulse shaping in a passive normally dispersive fibre and pulse generation in a dual-pump nonlinear-amplifying-loop-mirror mode-locked fibre laser.
关键词： pulse shaping,optical processing,nonlinear fibre optics,fibre lasers
更新于2025-09-23 15:21:01
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Excitation of Breather Solitons in a Mode-Locked Fibre Laser
摘要： We report on the generation and study of breathing dissipative solitons in a mode-locked fibre laser. Breathers exist in the laser cavity under the pump threshold of stationary mode locking. For the first time to our knowledge, breathing soliton molecules are also observed. Numerical simulations of the laser model support our experimental findings.
关键词： breather solitons,dissipative nonlinear systems,mode-locked fibre lasers
更新于2025-09-23 15:21:01
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Structural dynamics in proteins induced by and probed with X-ray free-electron laser pulses
摘要： X-ray free-electron lasers (XFELs) enable crystallographic structure determination beyond the limitations imposed upon synchrotron measurements by radiation damage. The need for very short XFEL pulses is relieved through gating of Bragg diffraction by loss of crystalline order as damage progresses, but not if ionization events are spatially non-uniform due to underlying elemental distributions, as in biological samples. Indeed, correlated movements of iron and sulfur ions were observed in XFEL-irradiated ferredoxin microcrystals using unusually long pulses of 80 fs. Here, we report a femtosecond time-resolved X-ray pump/X-ray probe experiment on protein nanocrystals. We observe changes in the protein backbone and aromatic residues as well as disulfide bridges. Simulations show that the latter’s correlated structural dynamics are much slower than expected for the predicted high atomic charge states due to significant impact of ion caging and plasma electron screening. This indicates that dense-environment effects can strongly affect local radiation damage-induced structural dynamics.
关键词： plasma electron screening,radiation damage,ion caging,structural dynamics,protein nanocrystals,X-ray free-electron lasers
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 14th Nanotechnology Materials and Devices Conference (NMDC) - Stockholm, Sweden (2019.10.27-2019.10.30)] 2019 IEEE 14th Nanotechnology Materials and Devices Conference (NMDC) - MOCVD synthesis of 2D saturable absorbers for pulsed fiber lasers
摘要： Nanolayers of MoSe2, NiO, VO2, Bi2Se3, Bi2Te3, Sb2Te3 compounds were fabricated using MOCVD technology. They were grown directly or mechanically deposited as a mixture with the polymer on the surface of tapered section of fibers. Tapers were fabricated by chemical etching. The deposition process was carried out in a special tubular quartz reactor with in-situ monitoring of optical transmission in the range of wavelength 1–1.65 μm. According to AFM, the deposited films consist of islands and occupy an insignificant part of the fiber surface. Tapers coated by 2D nanoislands were embedded in the ring circuit of an erbium fiber laser and tested as passive Q-switch. A transition from the continuous CW mode to the Q-switch mode was achieved for several samples with a taper diameter of less than 11 μm. For tapers of larger diameter the transition to the Q-switch mode was observed only when nanoislands of 2D compound were coated by polymer.
关键词： tapered fiber,2D materials,Q-swich,MOCVD method,erbium fiber ring lasers
更新于2025-09-23 15:21:01