- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Femtosecond Optical Annealing Induced Polymer Melting and Formation of Solid Droplets
摘要： Interaction between femtosecond laser pulses with polymeric thin films induced transient optical annealing of the polymer molecules. Melting of the polymer films took place during the transient annealing process, so that a solid-liquid-solid phase transition process was observed. Ultrafast cooling of the melting polymer produced solidified droplets. Microscopic and spectroscopic characterization revealed that the polymer molecules were rearranged with preferable H-aggregation to reach the lowest formation energy during the melting process. Intermolecular coupling was enhanced due to the modified molecular arrangement. This observation of melting of polymeric semiconductors due to the interaction with femtosecond light pulses is potentially important for better understanding laser-matter interactions and for exploring organic optoelectronic devices through special material processing.
关键词： transient optical annealing,melting polymer droplets,solid-liquid-solid phase transition,femtosecond laser-matter interaction,molecular rearrangement
更新于2025-09-23 15:22:29
-
A comprehensive approach for characterisation of the deposited energy density during laser-matter interaction in liquids and solids
摘要： We present a novel approach for characterisation of ultrafast laser-matter interaction processes both in solids and liquids under extreme conditions of microplasma generation. By combination of three-dimensional propagation imaging, absorption measurements, shadowgraphy and photoacoustic imaging we can restore plasma electron density distribution, laser pulse fluence profile and the value of deposited energy density inside the bulk of the material and characterise the regime of the laser pulse propagation. The developped concept is important to understand the physics of ultrafast laser-matter interaction with strong implications for precision control of laser micromachining, bioprocessing and biotreatment.
关键词： three-dimensional propagation imaging,photoacoustics,femtosecond filamentation,laser-matter interaction,deposited energy density,shadowgraphy
更新于2025-09-23 15:21:01
-
Direct and High-Throughput Fabrication of Mie-Resonant Metasurfaces <i>via</i> Single-Pulse Laser Interference
摘要： High-index dielectric metasurfaces featuring Mie-type electric and magnetic resonances have been of a great interest in a variety of applications such as imaging, sensing, photovoltaics and others, which led to the necessity of an efficient large-scale fabrication technique. To address this, here we demonstrate the use of single-pulse laser interference for direct patterning of an amorphous silicon film into an array of Mie resonators with few hundred nanometers in diameter. The proposed technique is based on laser-interference-induced dewetting. A precise control of the laser pulse energy enables the fabrication of ordered dielectric metasurfaces in areas spanning tens of micrometers and consisting of thousands of hemispherical nanoparticles with a single laser shot. The fabricated nanoparticles exhibit a wavelength-dependent optical response with a strong electric dipole signature. Variation of the pre-deposited silicon film thickness allows tailoring of the resonances in the targeted visible and infrared spectral ranges. Such direct and high-throughput fabrication is a step towards a simple realization of spatially invariant metasurface-based devices.
关键词： direct laser interference patterning,metasurfaces,laser-matter interaction,dielectric nanostructures,silicon resonators,multi-beam interference
更新于2025-09-23 15:19:57
-
Efficient absorption of laser light by nano-porous materials with well-controlled structure
摘要： The absorption of high-power nanosecond laser pulses in a porous matter is investigated through theoretical and numerical calculations. The effects of structural properties of the porous target such as size of pores and thickness of solid elements on the laser absorption are investigated. The time and space-dependent absorption coefficient of the laser created partially homogenized plasma is used in a plasma hydrodynamic code to reproduce the laser absorption and plasma formation processes in a porous matter. It is observed that the structural characteristics of the porous material can be optimized to significantly increase the laser energy absorption. For porous targets with pore sizes in the range 30–60 nm a value around 1000 nm could be desirable for the wall thickness to increase the laser absorption efficiency to more than 90%. The results can be advantageous in production of efficient laser absorber targets which are desirable in advanced applications such as inertial confinement fusion and laser-plasma x-ray sources.
关键词： laser produced plasma,laser–matter interaction,plasma absorption coefficient,porous targets
更新于2025-09-19 17:13:59
-
Direct observation of ultrafast electrons generated by high-intensity laser-matter interaction
摘要： High intensity ultrashort laser pulses interacting with thin solid targets are able to produce energetic protons and ions by means of extremely large accelerating fields, generated by escaping electrons. The characterization of such electrons is thus a key factor for the understanding of the accelerating potential temporal evolution. Here, we present temporally resolved measurements of the ultrafast escaping electron component. The charge, electric field, and temporal duration of the emitted ultrafast electron beams are determined using temporal diagnostics with a 100 fs temporal resolution. Experimental evidence of scaling laws for the ultrafast electron beam parameters with respect to the incident laser pulse energy is retrieved and compared with theoretical models, showing an excellent agreement.
关键词： ultrafast electrons,high-intensity laser-matter interaction,scaling laws,temporal diagnostics
更新于2025-09-19 17:13:59
-
High-Energy-Density Physics and Laser Technologies
摘要： This paper is devoted to the jubilee of I.M. Khalatnikov, the founder and the first director of the Landau Institute for Theoretical Physics of the Russian Academy of Sciences. I.M. Khalatnikov organized a first-class institute the studies at which cover a broad spectrum of research directions. The plasma and lasers department of the Institute conducts research on plasma physics problems, laser–matter interaction, questions pertaining to laser applications, and hydrodynamics problems. Much attention is given to solid-state physics with an emphasis on the behavior of matter in extreme conditions under intense laser irradiation. A number of new results are presented: the behavior of metals in two-temperature states (when the temperature of the electron subsystem of a metal is much greater than the temperature of the ion subsystem due to ultrafast laser heating); determining the boundaries of existence of a single-wave propagation mode of elastoplastic shock waves in ductile metal crystals; the formation of a laser torch from target materials and liquids under metal laser ablation of a metal into the surrounding liquid; the physical–mechanical consequences (melting, capillarity, recrystallization) of nonuniform (along the irradiated surface) energy dissipation caused by the interference of plasmon–polariton and laser electromagnetic fields.
关键词： laser–matter interaction,plasma physics,laser ablation,hydrodynamics,two-temperature states,plasmon–polariton,solid-state physics,high-energy-density physics,laser technologies,elastoplastic shock waves
更新于2025-09-12 10:27:22