scholarly journals Multiscale Hierarchical Micro/Nanostructures Created by Femtosecond Laser Ablation in Liquids for Polarization-Dependent Broadband Antireflection

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1573
Author(s):  
Dongshi Zhang ◽  
Bikas Ranjan ◽  
Takuo Tanaka ◽  
Koji Sugioka
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Light Trapping ◽  
Femtosecond Laser Ablation ◽  
Surface Structures ◽  
Mid Infrared ◽  
Periodic Surface ◽  
Broadband Antireflection ◽  
20 Nm ◽  
Light Absorbance

In this work, we present the possibility of producing multiscale hierarchical micro/nanostructures by the femtosecond laser ablation of transition metals (i.e., Ta and W) in water and investigate their polarization-dependent reflectance. The hierarchical micro/nanostructures are composed of microscale-grooved, mountain-like and pit-rich structures decorated with hybrid laser-induced periodic surface structures (LIPSSs). The hybrid LIPSSs consist of low/high and ultrahigh spatial frequency LIPSSs (LSFLs/HSFLs and UHSFLs). LSFLs/HSFLs of 400–600 nm in a period are typically oriented perpendicular to the direction of the laser polarization, while UHSFLs (widths: 10–20 nm and periods: 30–50 nm) are oriented perpendicular to the curvatures of LSFLs/HSFLs. On the microstructures with height gradients, the orientations of LSFLs/HSFLs are misaligned by 18°. On the ablated W metasurface, two kinds of UHSFLs are observed. UHSFLs become parallel nanowires in the deep troughs of LSFLs/HSFLs but result in being very chaotic in shallow LSFLs, turning into polygonal nanonetworks. In contrast, chaotic USFLs are not found on the ablated Ta metasurfaces. With the help of Fourier transform infrared spectroscopy, it is found that microgrooves show an obvious polarization-dependent reflectance at wavelengths of 15 and 17.5 μm associated with the direction of the groove, and the integration of microstructures with LSFs/HSFLs/UHSFLs is thus beneficial for enhancing the light absorbance and light trapping in the near-to-mid-infrared (NIR-MIR) range.

scholarly journals Fabrication of Diamond Membranes by Femtosecond Laser Ablation for MEMS Sensor Applications

Proceedings ◽  
2020 ◽  
Vol 56 (1) ◽  
pp. 13
Author(s):  
Johann Zehetner ◽  
Alexander Kromka ◽  
Tibor Izsák ◽  
Gabriel Vanko ◽  
Lenka Gajdošová ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Surface Chemistry ◽  
Membrane Surface ◽  
Femtosecond Laser Ablation ◽  
Surface Structures ◽  
Ablation Process ◽  
Periodic Surface ◽  
Sensor Applications ◽  
Mems Sensor

We present the feasibility in fabricating membranes and cantilevers made of diamond grown on Si/SiO2 substrates by femtosecond laser ablation. In the ablation process, we generated nano- and microstructures on the membrane surface. Such laser-induced periodic surface structures (LIPSS) are useful in tailoring the surface chemistry. In combination with wet or reactive ion etching, smooth membranes were generated.

Flower-like Na2O nanotip synthesis via femtosecond laser ablation of glass

2021 ◽  
Author(s):  
Champika Samarasekera ◽  
Bo Tan ◽  
Krishnan Venkatakrishnan
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Materials Science ◽  
Femtosecond Laser Ablation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Soda Lime Glass Substrate ◽  
Current State ◽  
Condition Method ◽  
20 Nm

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

scholarly journals Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 429 ◽  
Author(s):  
Leonardo Piccolo ◽  
Marco Sorgato ◽  
Afif Batal ◽  
Stefan Dimov ◽  
Giovanni Lucchetta ◽  
...  
Keyword(s):  
Contact Angle ◽  
Laser Ablation ◽  
Injection Molding ◽  
Femtosecond Laser Ablation ◽  
Cost Effective ◽  
Surface Structures ◽  
Periodic Surface ◽  
Wetting Behavior ◽  
Static Contact ◽  
Plastic Parts

Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of sub-micron textured plastic parts using laser ablation. The study includes the generation of different sub-micron structures on the surface of a mold using femtosecond laser ablation and vario-thermal micro-injection molding. The manufactured parts and their surfaces are characterized in consideration of polymer replication and wetting behavior. The results of the static contact angle measurements show that replicated Laser-Induced Periodic Surface Structures (LIPSSs) always increase the hydrophobicity of plastic parts. A maximum contact angle increase of 20% was found by optimizing the manufacturing thermal boundary conditions. The wetting behavior is linked to the transition from a Wenzel to Cassie–Baxter state, and is crucial in optimizing the injection molding cycle time.

scholarly journals Flower-like Na2O nanotip synthesis via femtosecond laser ablation of glass

2021 ◽  
Author(s):  
Champika Samarasekera ◽  
Bo Tan ◽  
Krishnan Venkatakrishnan
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Materials Science ◽  
Femtosecond Laser Ablation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Soda Lime Glass Substrate ◽  
Current State ◽  
Condition Method ◽  
20 Nm

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

scholarly journals Flower-like Na2O nanotip synthesis via femtosecond laser ablation of glass

2021 ◽  
Author(s):  
Champika Samarasekera ◽  
Bo Tan ◽  
Krishnan Venkatakrishnan
Keyword(s):  
Laser Ablation ◽  
Femtosecond Laser ◽  
Materials Science ◽  
Femtosecond Laser Ablation ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Soda Lime Glass Substrate ◽  
Current State ◽  
Condition Method ◽  
20 Nm

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

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