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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
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A 142 W Ho:YAG laser single-end-pumped by a Tm-doped fiber laser at 1931 nm
摘要： In this paper, a high-power Ho:YAG laser in-band pumped by a Tm-doped fiber laser at 1931 nm is reported. A maximum output power of 142.2 W is achieved at 2091 nm using a single-end-pumped configuration, corresponding to a slope efficiency of 56.7%. This is, to the best of our knowledge, the highest output power directly generated by bulk Ho-oscillators in the 2.1 μm spectral region.
关键词： fiber laser,Ho:YAG,solid state laser
更新于2025-09-12 10:27:22
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Widely Tunable, 25-mW Power, Ti:sapphire Crystal-Fiber Laser
摘要： Using a glass-clad Ti:sapphire crystal fiber (CF) as the gain medium, we demonstrate for the first time a diode-pumped, 25-mW tunable laser with a 180-nm tuning range. Active medium is a 2.4-cm long, a-cut Ti:sapphire CF we have drawn with an elliptical core of 13-μm diameter in the [0001] axis and 15.5-μm diameter in the [1ˉ100] axis. The CF is cladded with silica and has high efficiency (88%) of coupling to the pump, a diode laser emitting 1-W at 520-nm. A blazed grating provides a continuous smooth tuning on the wavelength range from 700 to 880 nm.
关键词： fiber lasers,Tunable solid-state lasers,crystalline materials,optical coherence tomography
更新于2025-09-12 10:27:22
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Feasibility study of a proton fluence monitor for LEO-Nanosatellite missions based on displacement damage induced in GaAs-LED
摘要： High-energy protons trigger irreparable displacement damage (DD) in unbiased Gallium Arsenide (GaAs) Light-Emitting Diode GaAs-LED (GAL). The DD is caused by non-ionizing-energy-loss (NIEL) process and results in reduction of light emission of the GAL when connected to a power source. Based on this finding a lightweight, low current consuming proton detector for space applications was developed. A commercial off the shelf (COTS) yellow GAL optically coupled to a Light-to-Frequency converter chip (LFC) made the basic assembly of the proposed proton detector. The device was calibrated using selected GAL samples irradiated with a 180 MeV proton beam from a proton-therapy medical cyclotron to 2, 10, 50, 100, 200 and 300 Gy dose levels. The light output of the GAL was measured with the detector assembly and presented as frequency (kHz). Protons of energy distribution between 100 keV to ～500 MeV are trapped in the inner-shell of the Van Allen belt (VAB) surrounding the earth, whereas the intensity of trapped electrons (Emax ～10 MeV) remains insignificant. The GAL light output data (frequency) was fitted with a second-degree polynomial function of imparted proton dose (～ number of protons). The results were parameterized for widely used NASA radiation belt models AP8-Max and AP8-Min using the proton NIEL distribution in Gallium Arsenide (GaAs). Spacecrafts, in particular Nanosatellites operating in low earth orbit (LEO) environment are primarily exposed to those trapped protons in the VAB. Nanosatellites endure severe radiation exposure while passing through the South Atlantic Anomaly (SAA) region. The footprint, mass and average current consumption of the proton detector was 0.027 cm2, 0.28 g and 2.5 mA respectively. The highest detectable level proton fluence (protons·cm?2) was evaluated to be 1.17 × 109 and 1.01 × 109 for AP8-Max and AP8-Min models respectively. Hence the proposed GAL based radiation detector is only suited for proton fluence monitoring on board LEO-Nanosatellites (NanoSat) of short lifetime, usually 6–18 months.
关键词： Particle detectors,Solid state detectors,Dosimetry concepts and apparatus
更新于2025-09-12 10:27:22
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2?kHz single-frequency, injection-seeded Q-switched laser with a ‘double-reflection’ architecture
摘要： A high-repetition-rate single-frequency injection-seeded Q-switched Er:YAG laser with a ‘double reflection’ architecture is reported. Single-frequency laser pulses at a pulse repetition frequency (PRF) of 2 kHz are obtained by using ‘ramp-fire’ injection-seeding technique. The half-width of the pulse spectrum is measured to be 2.05 MHz by using the heterodyne beating technique. The novel ‘double-reflection’ architecture is employed in order to achieve a stable high-repetition-rate single-frequency operation. As far as we know, 2 kHz is the highest PRF achieved from a single-frequency, injection-seeded Q-switched Er:YAG laser that can be used in a wind Lidar system.
关键词： single-frequency lasers,eye-safe lasers,solid-state lasers,Q-switching,diode-pumped lasers,injection-seeding,Er:YAG lasers
更新于2025-09-12 10:27:22
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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) - Comparison of Nd:YVO <sub/>4</sub> -Based Monolithic Microchip Laser Resonators for Single-Frequency Stable, CW Diode-Pumped Laser Sources
摘要： Single-frequency stable, narrow linewidth diode-pumped solid state (DPSS) lasers are commonly used in many applications and science areas, like high-resolution spectroscopy, optical metrology, gravity-wave detection, fundamental physics and others. Many of them require optical amplification of the DPSS seed laser to obtain higher output power while maintaining the excellent optical properties of the laser beam (e.g. Coherent Power Summation for military applications). In Ref.[2] the miniature, single-frequency stable DPSS laser operating at 1064 nm and patented structure of the monolithic microchip resonator Nd:YVO4/YVO4/YVO4 were described (Fig.1a). However, from commercial point of view the DPSS seed laser needs to be inexpensive, mechanically and optically stable for wide temperature range, easy to assemble and service. Here, the comparison of the 0.3 mm long a-cut Nd:YVO4 crystal resonator (Fig. 1b) with dielectric mirrors directly deposited onto the outer crystal surfaces (short resonator-SR) and described in Ref.[3] the 8.5mm long microchip resonator Nd:YVO4/YVO4/YVO4 (long resonator-LR) is presented for the first time. Both resonators were examined in the same DPSS laser module, providing the same conditions for their operation and they were pumped through a 3.5 mm long GRIN-lens collimator (Casix) by a linearly polarized 1W multimode 808 nm laser diode (QA-808-1000-030, Axcel Photonics). In comparison to the LR, the SR configuration provides only 27% less power conversion efficiency (at only 0.3mm resonator/gain crystal thickness) due to back reflection from HR@808nm coating of the pump beam. However, for the 808 nm pump power lower than 250 mW, the SR ensures slightly more output power than LR configuration due to 10-times lower power threshold (Fig. 1c). The pure single longitudinal mode operation was obtained for both configurations (Fig. 1e), nonetheless the SR provides almost 9-times wider temperature range (14-32°C @ 550mW of pump power) where laser resonator works in single mode (SM) regime (Fig. 1d), than the LR chip (21.2-23.2 °C @ 550mW of pump power). Additionally, the SR configuration does not need a crystals bonding process and it is around 25% cheaper (excluding bonding costs) compared to the LR. Whereas, the output beam divergence becomes around 4-times higher for the SR and it is more sensitive to angular aligning of the pump beam causing that transverse mode distribution can occur. Presented results and comparison were carried out within a commercial TANGO project “Development, optimization and integration of the single frequency seed laser operating at 1064 nm with medium power fiber amplifier”, (TANGO1/266345/NCBR/2015) financed by National Centre for Research and Development (NCBiR), Poland and statutory funds of the Faculty of Electronics (0401/0030/18).
关键词： single-frequency,optical amplification,diode-pumped solid state lasers,monolithic microchip laser,Nd:YVO4
更新于2025-09-12 10:27:22
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Effect of mono- and di-anchoring dyes based on o,m-difluoro substituted phenylene spacer in liquid and solid state dye sensitized solar cells
摘要： Novel mono- and di-anchoring organic dyes have been designed and synthesized with o,m-difluoro substituted phenylene spacer and were tested for DSSCs in presence of solid-state (SJE-4) as well as liquid (BMII) electrolytes. The new and simple structures of Cz-D1 and Cz-D2 dyes have same carbazole donor unit with either one or two side substitution of o,m-difluoro substituted phenylene π-spacer and cyanoacrylic acid acceptor. The photophysical and electrochemical properties of photosensitizes are investigated in detail and correlated with the solar cell performance. The Cz-D2 dye have ~20% higher device efficiency than Cz-D1 due to its lower LUMO level, and presence of two acceptor groups which provide efficient electron extraction from carbazole donor, lesser aggregation, high molar extinction coefficient and better charge transfer. Without using any additive, Cz-D2 exhibited an attractive power conversion efficiency (PCE) of 5.35% (Jsc ? 10.38 mA/cm2, Voc ? 0.75 V and FF ? 0.60) in presence of iodide redox electrolyte. These dyes exhibit comparatively less efficiency when used to fabricate a solid state dye sensitized solar cell in presence of SJE-4 electrolyte due to aggregation between fluorine substituted phenylene spacer and electrolyte through strong H-bonding that might cause more electron recombination/back electron transfer. Good stability was also observed for both the dyes.
关键词： o,m-difluoro,Dye sensitized solar cell,Stability,Mono- and di-anchor,Solid state electrolyte
更新于2025-09-12 10:27:22
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Insights into the formation of N doped 3D-Graphene Quantum Dots. Spectroscopic and Computational Approach
摘要： In this work, we utilize a top-down approach to synthesize nitrogen doped graphene quantum dots from a 3D-graphene precursor via an eco-friendly hydrothermal method. The nanoparticles obtained showed a 2-3 nm diameter and well dispersion behavior in aqueous media. The reaction mechanism of insertion of nitrogen from polyvinylpolypyrrolidone onto the 3D-graphene structure, via an esterification reaction, was studied by the density functional theory, in addition, the kinetic and thermodynamic magnitudes of the reaction was analyzed with the help of Eyring's transition state theory and statistical thermodynamics. After analysis by ss-NMR and XPS spectroscopies, the functional groups involved in this process were characterized, and N was found mainly as amide / amine groups. Fluorescence emission, which exhibited a red shift (552 nm) and an emission maximum at 512 nm when excited at 480 nm, demonstrated a low stoke shift (Δλ =32 nm), explained by the proposed structural model.
关键词： XPS,solid-state NMR,Nitrogen doped graphene quantum dots,DFT calculations
更新于2025-09-12 10:27:22
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High Efficiency Perovskite Solar Cells: Materials and Devices Engineering
摘要： Since the first report on 9.7% efficient solid-state perovskite solar cell (PSC) in 2012, perovskite photovoltaics received tremendous attentions. Efforts to increase power conversion efficiency (PCE) have been continuously made. As a result, a record PCE of 25.2% was certified in 2019, which surpassed those achieved from the conventional solar cells based on CIGS and CdTe. The superb photovoltaic performance of PSC is related to the defect-tolerant property, the long carrier lifetime, the long diffusion length of photo-generated carriers, and the high absorption coefficient. In this review, materials and devices engineering are described for achieving stability and higher PCE in PSCs. From the practical point of view, key technologies for materials, coating, and device fabrication are described, which is expected to be helpful to achieve high efficiency PSCs. Moreover, interfacial engineering methodologies toward hysteresis-less and stable PSCs are also presented to give insight into better understanding ion migration and recombination in PSCs.
关键词： Solid-state,Perovskite solar cell,High efficiency,Hysteresis-less,Interfacial engineering,Stability,Coating
更新于2025-09-12 10:27:22
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Maskless Patterning of Metal Outflow in Alternating Metal/Ceramic Multiple Nanolayers by Femtosecond Laser Irradiation
摘要： In this work, solid-state metal transport from internal metal nanolayers onto the surface of metal/ceramic nano-multi-layers (NMLs) has been directed in a controlled way by femtosecond (fs) laser irradiation and subsequent low temperature thermal annealing. Laser irradiation induced modifications of the NML microstructures and stress states can be limited within the first few top nanolayers due to the focused laser energy input at the metal/ceramic interface by exploiting the local plasmonic effect. Accompanied laser peening can further refine the crystallites and introduce compressive stress at the laser-irradiated region, which reduces the activation energies for vacancy formation and migration of metal atoms in the nano-confinement. Patterned Cu surface nanostructures (outflow) appear selectively along the laser path after air annealing at temperatures down to 360 ℃. For the solid-state diffusion of Cu in confinement, in-plane metal transport along the Cu-AlN interfaces is much faster than the outward short-circuit diffusion of Cu across the AlN barrier layers. Localized metal outflow is accompanied by the collapse and sintering of the remaining AlN barrier layers, under influence of the acting capillary forces, which may further accelerate the metal transport. This laser induced maskless patterning of metal outflow is not only applicable in Cu/AlN NMLs, but also in Ag/AlN NMLs, assisted by subsequent low temperature annealing.
关键词： solid-state metal transport,laser peening,metal/ceramic nanolayers,femtosecond laser,plasmonic effect
更新于2025-09-12 10:27:22