Short Laser Research Articles

Generation of subcycle isolated attosecond pulses by pumping ionizing gating

We present an interesting approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a preexisting gas grating, creating a fast-extending plasma grating (FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a subcycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs from long picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6 ps, 1 µm pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%. These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity. Published by the American Physical Society 2024

Comparative analysis of short-term outcomes after surgical treatment of varicose disease with endovasal laser obliteration and short stripping

The purpose of this study was to compare outcomes (within six months) after short stripping (SS) and endovenous laser obliteration (EVLO) in patients with varicose veins when analyzing ultrasound findings, postoperative complications, level of postoperative pain, clinical manifestations, and duration of rehabilitation after the intervention. Patients with varicose veins of lower extremities and insufficiency of large saphenous vein valves had either EVLO or SS with miniflebectomy. All patients were examined before surgery and then in 5 days, 10 days and in 1, 3 and 6 months after it. The patients also had clinical examination, ultrasound duplex scanning of their lower extremity veins; Venous Clinical Severity Score (VCSS) was also used for the trial. Pain was assessed during the first 10 days after the surgery using a 10-point pain assessment scale. 156 patients (177 lower extremities) were followed-up for 6 months. As the results of our study showed, endovenous laser obliteration and short stripping were equally effective in eliminating the reflux of the great saphenous vein (GSV). After 6 months of follow-up, the reflux along the medial inflow was noted in one case in SS group; partial GSV recanalization was noted in one case in EVLO group in 3 months, in 3 cases – in 6 months. Besides, despite LMH preventive doses one patient from EVLO group had EHIT II deep vein thrombosis. The obtained outcomes have demonstrated that EVLO and SS have similar effectiveness and safety. No difference has been found between these two types of treatment, except more pronounced postoperative pain and bruising in SS group. Performed care was equally safe and effective in eliminating GSV reflux, in relieving symptoms and eliminating varicose veins as well as in improving the quality of life. Long-term outcomes, especially the rate of relapses depending on the type of intervention, are to be investigated in future trials.

Safety of high-power short pulse single spot diode laser stapedotomy: an experimental animal study

Background We present a new method of diode laser stapedoplasty – high-power short-pulse mode with preliminary carbonization of the waveguide and a single spot of laser ablation. Aims/objective The aim of our research is the safety evaluation of presented mode 0.98 µm diode laser cochleostomy in guinea pigs. Material and methods Guinea pigs (n = 10) received 0.98 µm diode laser cochleostomy on one ear under general anesthesia. The control group was based on untreated ears (n = 10). The assessment of auditory function was performed using the distortion product otoacoustic emission (DPOAE) before and 7 d after surgery. To assess the degree of damage from the laser cochleas were extracted for histological examination. Results To evaluate the negative impact of laser energy on OHCs and auditory function, we analyzed DPOAE amplitudes for 6400 and 8000 Hz since high frequency. The paired Student’s t-test showed no statistically significant difference between the two groups. The histological examination yielded no statistically significant difference in the number of intact OHCs in the two groups. Conclusion and significance Our study confirms that the proposed method of high-power short pulse diode laser stapedotomy is safe for the inner ear. Further prospective and randomized clinical trials are required to evaluate the possible benefits of this method.

Physical and Luminescence Studies of Er3+-Doped into Borate Glass for IR Lighting Application

The gadolinium tungsten borate glasses doped with Er3+ were prepared by melt quenching technique for study in physical, absorption and luminescence properties. The glass composition (30-x) B2O3 − 27.5 Gd2O3 − 42.5 WO3 – x Er2O3, where x = 0.1, 0.5, 1.0 and 2.0 mol%. The results show that doping Er2O3 in higher concentration make the glass density and molar volume increases. The absorption spectra indicate the photon absorbing of Er3+ in visible light and near-infrared region. The emission spectra of these glasses have been recorded under 275 nm (Gd3+) and 380 nm (Er3+) excitation wavelength and it is observed that these glasses show green 550 nm and red 577 nm. NIR photoluminescence under 311 nm (Gd3+), 524 nm (Er3+) and 978 nm (Er3+), excitation was measured of glass in the region 1400–1700 nm. NIR emissions show a peak centered at 1543 nm. The luminescence of an erbium-doped glass was investigated at room temperature. In addition, mechanisms of the luminescence by multiphoton absorption and energy transfer processes are discussed based on the energy-level diagram of Er3+ and luminescence spectra. These results benefit for efficient short and conventional-length optical amplifiers and tunable lasers.

Microdrilled tapers to enhance optical fiber lasers for sensing

In this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector.

Preface to the special topic: Ultra short ultra intense laser plasma physics

Preface to the special topic: Ultra short ultra intense laser plasma physics

Stabilized, short cavity Brillouin ring laser source design for fiber sensing applications

A new pump-seeded, short-cavity Brillouin ring laser source layout intended for Brillouin sensing applications is showcased, showing increased high maximum output (1.5 mW), a strong linewidth narrowing effect (producing light with a linewidth of 10 kHz) and limited RIN (~-145 dB/Hz), providing an ultranarrow, highly stable BRL source that can also be employed as a pump-probe source for BOTDA applications.

Proposal for experimentally observing expectant ball lightning

Ball lightning is widely concerning because it is hard to detect, predict, and reproduce. The dependences of electromagnetic (EM) solitons, which are considered expectant ball lightning, forming at the wavelength of the incident light are investigated with two-dimensional particle-in-cell simulations. It shows that both the long wavelength microwave and the short wavelength laser are not suitable for producing the observed ball-lightning-like EM solitons. A strong field terahertz wave is proposed to inject and generate EM solitons. This paper can provide some references for researchers studying ball lightning.

Comparative Study of Er3+ Ions Doped Phosphate Based Oxide and Oxy-fluoride Glasses for Lasers Applications

Abstract Er3+ ions doped sodium strontium gadolinium oxide and oxy-fluoride phosphate glass samples prepared by conventional melt quenching technique. The samples were melted at 1200 °C in electric furnace with alumina crucibles. The densities of the samples were measure with the help of Archimedes principle using water as immersion liquid. The refractive index (n) was measured by Abbe refractometer with a sodium-vapour lamp as a light source and using mono-bromonaphthalene (C10H7Br) as a contact liquid. The prepared glass samples were characterized with UV-Vis-NIR absorptions and NIR photoluminescence. The UV-Vis-NIR spectra show peaks at 379, 406, 488, 521, 548, 652, 803, 977, and 1536 nm which are due to the transitions from 4 I15/2 ground state to 2H9/2, 4F3/2, 4F7/2, 4H11/2, 4S3/2, 4F9/2, 4I11/2 and 4I13/2 exited states of Er3+ ions, respectively. In NIR emission one broad peak at 1543 nm is observed in present glass samples with 379 nm excitation. From NIR emission it is observed that the FFEr glass give better emission intensity than the GEr and FEr. McCumber theory was used to evaluate stimulated emission cross-section of 4I13/2→4I15/2 transition of Er3+ ion using the absorption spectral measurements. Thus, these results show that present glasses have the potential for use in efficient short and conventional-length optical amplifiers and tuneable lasers

Preparation of a visible light-responsive gold nanoparticle-containing collagen gel microarray for in situ cell separation

Gold nanoparticle (AuNP)-embedded collagen gels have been prepared as a visible light-responsive cell scaffold that is applied to a visible light-induced in situ single cell detachment system. In this study, the visible light-responsive cell scaffold is combined with microarray technology for high-throughput cell separation. The AuNP-embedded collagen gel microarrays were prepared by pressing microarrays with 200 μm pores into the AuNP-embedded collagen gel. The microsized AuNP-embedded collagen gel was downsized to one thousandth of the conventional gel produced in a 96-well plate. Efficient thermal deformation of the microsized collagen gel was exhibited after laser irradiation for several seconds, which suggested that the microsized collagen gels had high sensitivity to the photothermogenic property. A collagen gel microarray with an AuNP coating at the bottom was also prepared; this exhibited morphological change after a shorter laser irradiation period than the AuNP-embedded collagen gel microarray. The cells cultured on the AuNP-embedded collagen gels were dead after laser irradiation but still alive on the collagen gel with the AuNP coating at the bottom. Thus, the AuNP-coated collagen gel microarray might work as a cell-friendly visible light-induced in situ single cell detachment system.

Initial Experiences Using Super Pulse Thulium Fiber Laser: Multipurpose Applications and the Assessment of Urologists' First Impression

Abstract Introduction: The super pulse thulium fiber (SPTF) laser has recently been acclaimed by more efficient lithotripsy activities, shorter laser, and treatment times demonstrated in preclinica...

Q-Switched and Mode-Locked Nd/Cr:YAG Ceramic Pulse Laser

A mode-locked and Q-switched short pulse laser using the Nd3+/Cr3+:YAG ceramic has been constructed with a SESAM and Cr4+:YAG crystal optical switch based on excite state absorption (ESA). Laser oscillations of the pulse laser were observed experimentally. The Nd/Cr:YAG ceramic laser has a high conversion efficiency from white light (such as lamp light or solar light) to the laser. The Nd/Cr:YAG ceramic has a higher laser gain than the Nd:YAG laser for the same pumping power. The laser oscillation can be obtained very easily. A single-mode-locked laser pulse with fast modulation on the order of 100 ps was obtained in some pump power regimes when using the Cr4+:YAG crystal. The obtained pulse duration of the short pulse was a few hundred ps. A maximum peak power of 60 kW was obtained when using a SESAM. The same level of peak power (60 kW) was also obtained when using the Cr4+:YAG crystal.

Generation and modulation of terahertz gradient force in the interactions of two-color laser pulses with magnetized plasmas

Terahertz (THz) waves, as far-infrared light, offer new opportunities for the optical trapping and manipulation of single cells, in contrast to the other light sources. We present an efficient scheme to flexibly control multiple THz field distribution patterns generated by the laser–plasma interaction in a magnetized plasma. An analytical THz radiation field and two-dimensional particle-in-cell simulation are constructed to verify the feasibility of the scheme. Modulation of the THz gradient force and the energy flux by an asymmetrical THz field is investigated for the purpose of trapping and manipulating particles and cells. In particular, the stabilities of flexibly controlled THz radiation are investigated carefully in the form of the strong and short laser and super-strong magnetic field induced significant spatial structure instabilities and frequency instabilities of terahertz radiation.

Peculiarities of phase formation in the mechanosynthesized titanium carbohydride powders under short pulse selective laser alloying

The authors analyze peculiarities of the phase formation and morphology of the titanium carbohydride coatings deposited on the steel substrates by means of short pulse selective laser alloying. Ti(C,H) powders with a particle size of 0.5–5 μm have been preliminarily produced by mechanical activation of titanium in petroleum ether. Heating up to 900°C results in the decomposition of the titanium carbohydride with the formation of TiC and Ti. The coatings deposited under laser alloying of carbohydride and steel substrate contain 50 vol.% of the “core–shell” inclusions with TiC as a core and TiFe2 and TiFe intermetallic compounds as a shell. Inclusions are of rounded shape both with a size of 50 to 200 nm, and the dendritic one is of up to 5 μm. Coatings up to 10 microns thick have a gradient pore-free structure and do not wear out under dry friction on hardened steel. Their microhardness is of 1016 HV, with a friction coefficient being 0.2. The proposed new in-situ technique for producing titanium-carbide-based coatings may be used for developing other metal carbide coatings with high performance characteristics.

短/超短脉冲激光诱导等离子体微加工研究进展

短/超短脉冲激光诱导等离子体微加工研究进展

The effect of short pulse laser irradiation on metals wetted by small amount of liquid

The effect of short pulse laser irradiation on metals wetted by small amount of liquid

Development of a Short Pulse Broadband and Narrow Linewidth Ultraviolet Laser Using Ce:LiCAF Crystal

We report the successful development of an all-solid state laser based on a Czochralski method-grown cerium-doped lithium calcium aluminum fluoride (Ce3+:LiCaAlF6 or Ce:LiCAF) crystal as the gain medium. Results for the broadband, narrow linewidth and short pulse laser emission are obtained by pumping the crystal with 7 ns pulses from the fourth harmonics (266 nm) of a Nd:YAG laser operating at 10 Hz. The effects of output coupler reflectivity, resonator length and pump energy on the laser pulse duration were explored. With broadband configuration, a maximum output pulse energy of 3.4 mJ and a slope efficiency of about 33% were achieved. By optimizing the parameters of the resonator and pump laser energy, 450 ps UV laser pulses were generated from resonator transient conditions of low-Q and short resonator under a near threshold pump energy. With narrow linewidth configuration, where the end mirror is replaced by a grating, tunability from 281 nm to 299 nm is also achieved with a linewidth of about 0.2 nm.

Simulation of Self-focusing of Femtosecond Laser Pulses with Normal Dispersion in Air Using the Diffraction-Beam Tube Approach

Based on numerical simulation and qualitative analysis, the effect of the group velocity dispersion on the formation of light structures during self-focusing and filamentation of femtosecond Ti:sapphire laser pulses in air is studied. The main features of the filamentation have been determined at various pulse duration, initial beam radii, and peak radiation powers based on the results of numerical solutions of the nonlinear Schrodinger equation in a Kerr-plasma dissipative dispersion medium and using the diffraction-beam tube approach. Dispersion is detected in the cases where the dispersion length is not a minimum at the scale of the process. It is shown that the relative (normalized to Rayleigh length) coordinate of the beginning of filamentation increases as the dispersion distortions of the pulse increase, and the filamentation channel length is reduced. For shorter laser pulses (tens of femtoseconds), the filamentation ceases as the laser beam radius increases. The size of the energy-replenishing diffraction-beam tube and the angular divergence of postfilamentation light channels increase for this class of pulses.

Plasma-based accelerators: then and now

An overview of the evolution of the experimental field of plasma accelerators driven by short laser or charge particle bunches and where it is headed is given.

Laser-irradiated gold nanoparticles for breast cancer therapy

Current study involves laser-induced gold nanoparticles (GNPs) for breast cancer therapy. GNPs as a therapeutic agent using nanophotolysis approach are discussed. Coulomb explosion of GNPs is studied numerically using MATLAB. Our findings show that [Formula: see text] ions are generated for short pulse laser interaction of 8 ns and laser irradiation of 2 J/cm2 penetrates in the tumor depth of 3.30 cm. Cluster size of 98 nm produced [Formula: see text] nanobullets that target the breast tumor. Short pulse laser of 2.27 ns generates maximum shock front velocity of [Formula: see text] cm/s. Shock front of 20–146 [Formula: see text]m is produced for effectively damaging the breast cancer tissues. A total of 825 cells are damaged by [Formula: see text] ions. Current results are matched with the literature and are in good correlation. Hence, we conclude that laser-irradiated GNPs using nanophotolysis approach are useful for targeted therapy of breast tumor.