Few Percent Efficient Polarization-Sensitive Conversion in Nonlinear Plasmonic Interactions Inside Oligomeric Gold Structures

The backscattering spectra of a 500 nm thick gold film, which was excited near the 525 nm transverse localized plasmon resonance of its constituent, self-organized, vertically-aligned nanorods by normally incident 515 nm, 300 fs laser pulses with linear, radial, azimuthal and circular polarizations, revealed a few-percent conversion into Stokes and anti-Stokes side-band peaks. The investigation of these spectral features based on the nanoscale characterization of the oligomeric structure and numerical simulations of its backscattering response indicated nonlinear Fano-like plasmonic interactions, particularly the partially degenerate four-wave mixing comprised by the visible-range transverse plasmon resonance of the individual nanorods and an IR-range collective mode of the oligomeric structure. Such oligomeric structures in plasmonic films may greatly enhance inner nonlinear electromagnetic interactions and inner near-IR hotspots, paving the way for their engineered IR tunability for broad applications in chemosensing and biosensing.

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Laser-Inscribed Stress-Induced Birefringence of Sapphire

Nanomaterials ◽

10.3390/nano9101414 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1414 ◽

Cited By ~ 3

Author(s):

Hua Fan ◽

Meguya Ryu ◽

Reo Honda ◽

Junko Morikawa ◽

Zhen-Ze Li ◽

...

Keyword(s):

Bessel Beam ◽

Laser Pulses ◽

Visible Spectral Range ◽

Vortex Generation ◽

Cross Sectional ◽

Optical Elements ◽

High Birefringence ◽

Self Organized ◽

Fs Laser ◽

Spatially Varying

Birefringence of 3 × 10 - 3 is demonstrated inside cross-sectional regions of 100 μ m, inscribed by axially stretched Bessel-beam-like fs-laser pulses along the c-axis inside sapphire. A high birefringence and retardance of λ / 4 at mid-visible spectral range (green) can be achieved using stretched beams with axial extension of 30–40 μ m. Chosen conditions of laser-writing ensure that there are no formations of self-organized nano-gratings. This method can be adopted for creation of polarization optical elements and fabrication of spatially varying birefringent patterns for optical vortex generation.

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Nanoscale Heat Transport in Self-Organized Ge Clusters on Si(001)

MRS Proceedings ◽

10.1557/opl.2013.148 ◽

2012 ◽

Vol 1456 ◽

Cited By ~ 1

Author(s):

Tim Frigge ◽

Annika Kalus ◽

Friedrich Klasing ◽

Martin Kammler ◽

Anja Hanisch-Blicharski ◽

...

Keyword(s):

Laser Pulses ◽

Transient Temperature ◽

Equivalent Thickness ◽

Time Resolved ◽

Pump Probe ◽

Nanoscale Heat Transport ◽

Self Organized ◽

Transmission Electron ◽

Fs Laser ◽

Cooling Behavior

ABSTRACTUltrafast time resolved transmission electron diffraction (TED) in a reflection geometry was used to study the cooling behavior of self-organized, well defined nanoscale germanium hut and dome clusters on Si(001). The clusters were heated in a pump-probe scheme by fs-laser pulses. The resulting transient temperature rise was then determined from the drop in diffraction intensity caused by the Debye-Waller effect. From a cooling time of τ =177 ps we estimated a strongly reduced heat transfer compared with homogeneous films of equivalent thickness.

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Laser-induced thermal grating spectroscopy based on femtosecond laser multi-photon absorption

Scientific Reports ◽

10.1038/s41598-021-89269-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Maria Ruchkina ◽

Dina Hot ◽

Pengji Ding ◽

Ali Hosseinnia ◽

Per-Erik Bengtsson ◽

...

Keyword(s):

Continuous Wave ◽

Laser Pulses ◽

Photon Absorption ◽

Gas Flows ◽

Single Shot ◽

Photon Excitation ◽

Fs Laser ◽

Thermal Grating ◽

Grating Spectroscopy ◽

First Time

AbstractLaser-induced grating spectroscopy (LIGS) is for the first time explored in a configuration based on the crossing of two focused femtosecond (fs) laser pulses (800-nm wavelength) and a focused continuous-wave (cw) laser beam (532-nm wavelength). A thermal grating was formed by multi-photon absorption of the fs-laser pulses by $$\hbox {N}_{{2}}$$ N 2 with a pulse energy around 700 $$\upmu $$ μ J ($$\sim $$ ∼ 45 TW/$$\hbox {cm}^{2}$$ cm 2 ). The feasibility of this LIGS configuration was investigated for thermometry in heated nitrogen gas flows. The temperature was varied from room temperature up to 750 K, producing strong single-shot LIGS signals. A model based on the solution of the linearized hydrodynamic equations was used to extract temperature information from single-shot experimental data, and the results show excellent agreement with the thermocouple measurements. Furthermore, the fluorescence produced by the fs-laser pulses was investigated. This study indicates an 8-photon absorption pathway for $$\hbox {N}_{{2}}$$ N 2 in order to reach the $$\hbox {B}^{3}\Pi _{g}$$ B 3 Π g state from the ground state, and 8 + 5 photon excitation to reach the $$\hbox {B}^{2}\Sigma _{u}^{+}$$ B 2 Σ u + state of the $$\hbox {N}_{2}^{+}$$ N 2 + ion. At pulse energies higher than 1 mJ, the LIGS signal was disturbed due to the generation of plasma. Additionally, measurements in argon gas and air were performed, where the LIGS signal for argon shows lower intensity compared to air and $$\hbox {N}_{{2}}$$ N 2 .

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Dual-shot dynamics and ultimate frequency of all-optical magnetic recording on GdFeCo

Light Science & Applications ◽

10.1038/s41377-020-00451-z ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Sicong Wang ◽

Chen Wei ◽

Yuanhua Feng ◽

Hongkun Cao ◽

Wenzhe Li ◽

...

Keyword(s):

Magnetization Reversal ◽

Energy Efficient ◽

High Speed ◽

Data Transfer ◽

Laser Pulses ◽

Time Resolved ◽

All Optical ◽

Fs Laser ◽

High Speed Data ◽

Natural Way

AbstractAlthough photonics presents the fastest and most energy-efficient method of data transfer, magnetism still offers the cheapest and most natural way to store data. The ultrafast and energy-efficient optical control of magnetism is presently a missing technological link that prevents us from reaching the next evolution in information processing. The discovery of all-optical magnetization reversal in GdFeCo with the help of 100 fs laser pulses has further aroused intense interest in this compelling problem. Although the applicability of this approach to high-speed data processing depends vitally on the maximum repetition rate of the switching, the latter remains virtually unknown. Here we experimentally unveil the ultimate frequency of repetitive all-optical magnetization reversal through time-resolved studies of the dual-shot magnetization dynamics in Gd27Fe63.87Co9.13. Varying the intensities of the shots and the shot-to-shot separation, we reveal the conditions for ultrafast writing and the fastest possible restoration of magnetic bits. It is shown that although magnetic writing launched by the first shot is completed after 100 ps, a reliable rewriting of the bit by the second shot requires separating the shots by at least 300 ps. Using two shots partially overlapping in space and minimally separated by 300 ps, we demonstrate an approach for GHz magnetic writing that can be scaled down to sizes below the diffraction limit.

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High-quality net shape geometries from additively manufactured parts using closed-loop controlled ablation with ultrashort laser pulses

Advanced Optical Technologies ◽

10.1515/aot-2019-0065 ◽

2020 ◽

Vol 9 (1-2) ◽

pp. 101-110 ◽

Cited By ~ 1

Author(s):

Daniel Holder ◽

Artur Leis ◽

Matthias Buser ◽

Rudolf Weber ◽

Thomas Graf

Keyword(s):

Surface Roughness ◽

Closed Loop ◽

High Surface ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Minimum Thickness ◽

High Quality ◽

Surface Optical ◽

The Individual ◽

Ultrashort Laser

AbstractAdditively manufactured parts typically deviate to some extent from the targeted net shape and exhibit high surface roughness due to the size of the powder grains that determines the minimum thickness of the individual slices and due to partially molten powder grains adhering on the surface. Optical coherence tomography (OCT)-based measurements and closed-loop controlled ablation with ultrashort laser pulses were utilized for the precise positioning of the LPBF-generated aluminum parts and for post-processing by selective laser ablation of the excessive material. As a result, high-quality net shape geometries were achieved with surface roughness, and deviation from the targeted net shape geometry reduced by 67% and 63%, respectively.

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Ultrafast Laser Cleaning of Daguerreotypes

MRS Proceedings ◽

10.1557/opl.2011.734 ◽

2011 ◽

Vol 1319 ◽

Cited By ~ 1

Author(s):

Michael J. Abere ◽

Ryan D. Murphy ◽

Bianca Jackson ◽

Gerard Mourou ◽

Michel Menu ◽

...

Keyword(s):

Material Removal ◽

Silver Oxide ◽

Laser Pulses ◽

Silver Sulfide ◽

Ultrafast Laser ◽

Beam Diameter ◽

Chemical Cleaning ◽

Silver Substrate ◽

Fs Laser ◽

Lower Material

ABSTRACTAn ultrafast laser irradiation method for the removal of corrosion from Daguerreotypes without detrimentally affecting image quality has been developed. Corrosion products such as silver oxide and silver sulfide may be removed by chemical cleaning but these reactions are hard to control and are often damaging to the underlying silver, ruining the image. The Ti:Sapphire 150 fs laser pulses used in this study are focused to a beam diameter of 60 μm and are normally incident to the Daguerreotype. It was found that the corrosion layer has a lower material removal threshold than silver allowing for removal of corrosion with minimal removal of vital information contained in the silver substrate.

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Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.16.15 ◽

2012 ◽

Vol 16 ◽

pp. 15-20 ◽

Cited By ~ 4

Author(s):

Omid Tayefeh Ghalehbeygi ◽

Vural Kara ◽

Levent Trabzon ◽

Selcuk Akturk ◽

Huseyin Kizil

Keyword(s):

Laser Ablation ◽

Femtosecond Laser ◽

Laser Beam ◽

Chemical Etching ◽

Silicon Surface ◽

Laser Pulses ◽

Laser Beam Profile ◽

Fs Laser ◽

Fabrication And Characterization

We fabricated Si Nano-columns by a femtosecond laser with various wavelengths and process parameters, whilst the specimen was submerged in water. The experiments were carried out by three types of wavelengths i.e. 1030 nm, 515nm, 343nm, with 500 fs laser pulses. The scales of these spikes are much smaller than micro spikes that are constructed by laser irradiation of silicon surface in vacuum or gases like SF6, Cl2. The Si nano-columns of 300 nm or less in width were characterized by SEM measurements. The formation of these Si Nano-columns that were revealed by SEM observation, indicates chemical etching with laser ablation occurred when surface exposed by laser beam. We observed 200 nm spikes height at the center of laser beam profile and the ones uniform in height at lateral incident area.

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Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

Applied Physics A ◽

10.1007/s00339-020-04179-w ◽

2020 ◽

Vol 127 (1) ◽

Author(s):

Daniel Metzner ◽

Peter Lickschat ◽

Steffen Weißmantel

Keyword(s):

Surface Treatment ◽

Picosecond Laser ◽

Laser Pulses ◽

Laser Source ◽

Time Interval ◽

Cobalt Chromium ◽

Burst Mode ◽

Self Organized ◽

Implant Alloys ◽

Cobalt Chromium Molybdenum

AbstractThe authors report on the results of surface treatment experiments using a solid-state amplified laser source emitting laser pulses with a pulse duration of 10 ps. The laser source allows the generation of pulse trains (bursts) with an intra-burst pulse repetition rate of 80 MHz (pulse-to-pulse time interval about 12.5 ns) with up to eight pulses per burst. In this study a wavelength of 1064 nm was used to investigate both ablation of material and laser-induced surface modifications occuring in metallic implant alloys CoCrMo (cobalt-chromium-molybdenum) and TiAlV (titanium-aluminum-vanadium) in dependence of the number of pulses and fluences per pulse in the burst. By using the burst mode, a smoothing effect occurs in a certain parameter range, resulting in very low surface roughness of the generated microstructures. It is demonstrated that at fluences per pulse which are smaller than the material-specific ablation threshold, a self-organized pore formation takes place if a defined number of pulses per burst is used. Thus, the advantage of the MHz burst mode in terms of a possible surface modification is established.

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