Karen L. van der Molen, Allard P. Mosk, Ad Lagendijk
We have measured the evolution of the light intensity of a random laser during a nanosecond pump pulse. Relaxation oscillations in a titania random laser were observed in the time trace of the total emitted intensity. We compare our experimental results with a simple model, based on the four-level rate equations for a single mode laser.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
The bias-pumped gain-switched fiber laser proposed by us is considered a novel pulsed fiber laser based on a new pulsing mechanism. With a certain signal power seeding, synchronization of temporal evolution can be kept between the output signal laser and the pump. The seed laser can be supplied conveniently by a CW pump power which is named bias pump power. A pulsed pump is responsible for shaping the output pulse. Stable pulsed lasers with tunable durations can be achieved under bias pump combined with pulsed pump. In addition, the temporal shape of output pulses can be controllable based on …
Rapid Photo-Bleaching of Gamma-Irradiated Yb-doped Optical Fibers by High-Energy Nanosecond Pulsed Laser
研究提出利用高能纳秒脉冲激光对10 kGy伽马辐照掺Yb光纤进行快速光漂白，发现增加照射时间和光子能量可提升漂白效果，色心恢复率在更短时间内达96%。
A novel approach is used to enhance by nearly two orders of magnitude the conversion efficiency of a 125 nm-coherent source, based on four-wave mixing in room-temperature mercury vapor. Saturation issues are observed and discussed.
Active frequency-chirp compensation for a narrowband pulsed Titanium-Sapphire laser system is demonstrated using an intra-cavity electro-optic modulator resulting in improved spectral resolution and stability. With referencing to an optical frequency comb and further residual frequency chirp detection from shot-to-shot measurements, the resulting laser pulses are frequency up-converted for high-precision spectroscopy measurements in the VUV regime, where the relative uncertainty contribution due to frequency chirp is pushed to the $5 \times 10^{-11}$ level.
Photoelectric effect in a Ge-on-Si single-photon avalanche detector (SPAD) at a sub-photon energy in incident pulsed laser radiation is considered in frames of classical electrodynamics of continuous media. It is shown that the energy of incident laser radiation, which is shared among a huge number of electrons in Ge matrix, can concentrate on only one of these through the effect of the constructive interference of the fields re-emitted by surrounding electrons. Conservation of energy in this case is upheld because of a substantial narrowing of the effective bandgap in heavily doped p-Ge, whic…
Sub-kHz single-frequency pulsed semiconductor laser based on NPRO injection locking
本文提出一种基于NPRO种子注入锁定和泵浦电流直接调制的单频脉冲半导体激光器，实现了亚千赫兹线宽、可调重复频率与脉冲宽度，适用于相干激光雷达、计量与遥感等领域。
New approach for the incoherent and coherent combination of pulsed lasers
本文提出脉冲激光相干与非相干合成新构型，通过仿真分析脉冲时域强度演化，揭示超短脉冲空间变细和旁瓣特征，并突破近轴光学对激光器数量与位置的限制。
Long-distance measurements (10 m - 1000 m) with an accuracy of 10-7 is a challenge for many applications. We show that it is achievable with Frequency Shifted Feedback (FSF) laser interferometry technique, provided that the determination of the radio frequency beat order be made without ambiguity and on a time scale compatible with atmospheric applications. Using the pulsed-FSF laser that we developed for laser guide star application, we propose and test, up to 240 m, a simple method for measuring the beat order in real time. The moving-comb and Yatsenko models are also discussed. The first of…
We report on the dependence of the frequency-to-intensity noise conversion in the locking of an ultrafast laser against a high-finesse optical resonator from the Carrier Envelope Offset (CEO) frequency. By a proper combination of the cavity finesse and laser CEO frequency it is possible to optimize the signal-to-noise ratio of the laser intensity trapped into the optical resonator. The theoretical description of the problem together with the numerical simulations and experimental results are presented with the aim of a strong suppression of the intensity fluctuations of the trapped laser field…
Metallic gratings were fabricated using high energy laser interference lithography with a frequency tripled Nd:YAG nanosecond laser. The grating structures were first recorded in a photosensitive layer and afterwards transferred to an Au film. High quality Au gratings with a period of 770 nm and peak-to-valley heights of 20-60 nm exhibiting plasmonic resonance response were successfully designed, fabricated and characterized.
A continuously tunable titanium:sapphire (Ti:Sa) laser self-seeded by an extended grating cavity was demonstrated and characterized. By inserting a partially reflecting mirror inside the cavity of a classic single-cavity grating laser, two oscillators are created: a broadband power oscillator, and a narrowband oscillator with a prism beam expander and a diffraction grating in Littrow configuration. By coupling the grating cavity oscillation into the power oscillator, a power-enhanced narrow-linewidth laser oscillation is achieved. Compared to the classic grating laser, this simple modification…
The efficiency of a coherent VUV source at 125 nm, based on 2-photon resonant four-wave mixing in mercury vapor, has been enhanced by up to 2 orders of magnitude. This enhancement was obtained by locally heating a liquid Hg surface with a pulsed excimer laser, resulting in a high density vapor plume in which the nonlinear interaction occurred. Energies up to 5 μJ (1 kW peak power) have been achieved while keeping the overall Hg cell at room temperature, avoiding the use of a complex heat pipe. We have observed a strong saturation of the VUV yield when peak power densities of the fundament…
The optical conductance of monolayer graphene is defined solely by the fine structure constant. The absorbance has been predicted to be independent of frequency. In principle, the interband optical absorption in zero-gap graphene could be saturated readily under strong excitation due to Pauli blocking. Here, we demonstrate the use of atomic layer graphene as saturable absorber in a mode-locked fiber laser for the generation of ultrashort soliton pulses (756 fs) at the telecommunication band. The modulation depth can be tuned in a wide range from 66.5% to 6.2% by varying the thickness of graphe…
Pulsed Optical Injection Steering in Multistable Semiconductor Laser Arrays under Correlated Noise
研究通过脉冲光学注入在小规模VCSEL阵列中实现鲁棒可编程状态准备，展示在无噪声条件下通过选择脉冲偏移和振幅可引导系统至任一稳定平衡分支，并在有相关噪声时验证了脉冲注入作为多稳态VCSEL阵列吸引子选择的实用机制。
It attracts wide interest to seek universe saturable absorber covering wavelengths from near infrared to mid-infrared band. Multilayer black phosphorus, with variable direct bandgap (0.3-2 eV) depending on the layer number, becomes a good alternative as a universe saturable absorber for pulsed lasers. In this contribution, we first experimentally demonstrated broadband saturable absorption of multilayer black phosphorus from 1 μm to 2.7 μm wavelength. With the as-fabricated black phosphorus nanoflakes as saturable absorber, stable Q-switching operation of bulk lasers at 1.03 μm, 1.93 μm, 2.72 …
The specific optical nonlinearities inherent in aggregates of metal nanoparticles under pico- and nanosecond pulsed laser irradiation are studied in nanoparticle aggregates formed in silver hydrosols. The results of experimental studies of the correlation between the degree of aggregation of silver hydrosols and their nonlinear refraction index at the wavelengths 0.532 and 1.064 microns are discussed. The experiments revealed that nonlinear refraction index changes its sign at 1.064 microns as the degree of the hydrosol aggregation grows. The role of various processes occurring in resonant dom…
Simulating real-time scenarios to predict optical trapping behavior for continuous wave (CW) as well as femtosecond pulsed lasers is a challenging problem. This is especially so, because, for a tightly focused laser, one must also include optical Kerr effect as well as thermal nonlinearity. We show here the distinct differences between CW and femtosecond pulsed laser mediated optical trapping via their effect in scattering and gradient forces in the Rayleigh regime. In our newly developed model, it will also be easier to predict the stability of the trap in real optical trapping scenario as we…
Beam shaping techniques for pulsed laser ablation in liquids: Unlocking tunable control of nanoparticle synthesis in liquids
本文探讨了通过引入束形技术改进脉冲激光在液体中烧蚀，以实现对液体中纳米粒子合成的可调控制。
Negative refraction with little loss manipulated by the voltage and pulsed laser in double quantum dots
本文提出通过电压和脉冲激光调控双量子点隧穿速率实现低损耗负折射，为固态系统负折射实验提供新途径。
The preparation in thin film form of the known icosahedral phase in Ti-Ni-Zr bulk alloys has been investigated as a function of substrate temperature. Films were deposited by Pulsed Laser Deposition on sapphire substrates at temperatures ranging from room temperature to 350$^\circ$C. Morphological and structural modifications have been followed by grazing incidence and $θ$-2$θ$ X-ray diffraction, transmission electron diffraction and imaging. Chemical composition has been analysed by Electron Probe Micro-Analysis. The in-depth variation of composition has been studied by Secondary Neutral Mass…
We report on the morphological effects induced by the inhomogeneous absorption of cylindrically polarized femtosecond laser irradiation of silver (Ag) in sub-ablation conditions. A theoretical prediction of the role of surface plasmon excitation in the production of self-formed periodic ripples structures is evaluated. Furthermore, a combined hydrodynamical and thermoelastic model is presented to account for the influence of temperature-related lattice movements in laser beam conditions that are sufficient to produce material melting. The ability to control the size of the morphological change…
We theoretically present a design of self-starting operation of microcombs based on laser-cavity solitons in a system composed of a micro-resonator nested in and coupled to an amplifying laser cavity. We demonstrate that it is possible to engineer the modulational-instability gain of the system's zero state to allow the start-up with a well-defined number of robust solitons. The approach can be implemented by using the system parameters, such as the cavity length mismatch and the gain shape, to control the number and repetition rate of the generated solitons. Because the setting does not requi…
QCL active region overheat in pulsed mode: effects of non-equilibrium heat dissipation on laser performance
本文利用热传导方程研究QCL有源区在脉冲模式下的非平衡过热，揭示合金低热导率对脉冲及CW散热的根本限制，并指出后生长结构仅影响近CW模式。
Phosphorescent emissions at room temperature from solid-state self sustained film fabricated using phenazine derivative molecules blended in a solution of poly(methyl methacrylate) were investigated at steady-state experimental conditions. Stripe excitation by a pulsed laser at different levels of intensities and different lengths of stripes, originates a guided emission up to the edge of the film, enabling us to assume higher gain characteristics for triplet states of the medium, due to the relatively higher contribution of the total integrated area for the phosphorescent part of the emission…
We present an experimental study of the turn-on delay in pulsed mid-infrared quantum cascade lasers. We report the unexpectedly long delay time depending on the pumping current, which does not agree with conventional theoretical predictions for step-like excitation. Similar behavior has been observed in InP- and InAs-based QCLs emitting near 8$μ$m. Numerical simulations performed using a model based on rate equations for excitation by current pulses with non-zero rise time provide fair agreement with our observations.
The controlled modulation of an optical wavefront is required for aberration correction, digital phase conjugation or patterned photostimulation. For most of these applications it is desirable to control the wavefront modulation at the highest rates possible. The digital micromirror device (DMD) presents a cost-effective solution to achieve high-speed modulation and often exceeds the speed of the more conventional liquid crystal spatial light modulator, but is inherently an amplitude modulator. Furthermore, spatial dispersion caused by DMD diffraction complicates its use with pulsed laser sour…
Temperature and mean axial momentum vs. laser intensity of electrons released from O$_2$ by an 800 nm ultrashort pulsed laser
研究800nm超短脉冲激光作用下O₂释放电子的温度和平均轴向动量与激光强度关系，提出半经验模型，通过修改理论动能谱及结合经典运动学与光谱拟合来估计平均动量，为电动流体模拟提供初始条件。
Non-volatile phase-change materials with large optical contrast are essential for future tunable nanophotonics. Antimony trisulfide (Sb2S3) has recently gained popularity in this field due to its low absorption in the visible spectral region. Although several Sb2S3 deposition techniques have been reported in the literature, none of them was optimized with respect to the lowest possible absorption and largest optical contrast upon the phase change. Here, we present a comprehensive multi-parameter optimization of pulsed laser deposition of Sb2S3 towards this end. We correlate the specific deposi…
High-energy chirped nanosecond pulsed laser system for particle diagnostics and manipulation
本研究升级了专为光学粒子诊断与操控定制的高能纳秒脉冲激光系统，使其脉冲能量达焦耳级以上，同时保留可调时间轮廓、脉宽及数GHz啁啾的能力，可降低粒子密度探测阈值并提升粒子操控效率，拓展了应用场景。
We propose a feedback-assisted direct laser writing method to perform laser ablation of fiber optics devices in which their light-collection signal is used to optimize their properties. A femtosecond-pulsed laser beam is used to ablate a metal coating deposited around a tapered optical fiber, employed to show the suitability of the approach to pattern devices with small radius of curvature. During processing, the same pulses generate two-photon fluorescence in the surrounding environment and the signal is monitored to identify different patterning regimes over time through spectral analysis. T…
We report a study on light force on a beam of neutral two-level atoms superimposed upon a few-cycle pulsed Gaussian laser field under both resonant and off-resonant condition. The phenomena of focusing, defocusing and steering of the neutral atoms in the laser field is analysed by solving the optical Bloch equation beyond the rotating wave approximation and the force equation self-consistently .We find that two-level atoms in an atomic beam could be focused and defocused for large, positively and negatively detuned interaction even in the regime of extreme nonlinear optics. The so-called optic…
Ultrafast pulsed laser evaluation of Single Event Transients in opto-couplers
本研究搭建了基于1064 nm光纤激光的测试系统以模拟电子元件的单粒子瞬态（SET），并首次利用该装置在4N35光电耦合器中观测到SET，为相关器件的辐射效应评估提供了测试手段。
The thermal response of a Cu-Ti double-layered film is investigated after laser irradiation with ultrashort pulses (pulse duration τp=50fs, 800nm laser wavelength) in submelting conditions by including the influence of nonthermal electrons. A revised two-temperature model is employed to account for the contribution of nonthermal electron distribution while the variation of the optical properties of the material during the laser beam irradiation is also incorporated into the model. Theoretical results can provide significant insight into the physical mechanism that characterize electron dynamic…
Ionization rate vs. laser intensity determined from ion count vs. peak intensity due to neutral gas exposure to an 800 nm ultrashort pulsed laser
该研究通过数值反演飞行时间离子光谱仪数据，确定Ar、O₂和N₂的光学周期平均电离率与激光强度关系，重新校准相关参数，得出O₂结果与已发表数据重新评估一致的结论。
We present a novel approach for tailoring the laser induced surface topography upon femtosecond-fs pulsed laser irradiation. The method employs spatially controlled double fs laser pulses to actively regulate the hydrodynamic microfluidic motion of the melted layer that gives rise to the structures formation. The pulse train used, in particular, consists of a previously unexplored spatiotemporal intensity combination including one pulse with Gaussian and another with periodically modulated intensity distribution created by Direct Laser Interference Patterning (DLIP). The interpulse delay is ap…
Emulation of the Six-State Quantum Key Distribution Protocol with Pulsed Lasers
针对量子密码教研需求，本文提出结合光学实验与计算分析的仿真框架，可低成本测试六态量子密钥分发协议，验证多基矢编码原理及实验测量与理论的关联。
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。