Ultrashort laser processing has great potential for precise microfabrication of transparent materials. For optimizing laser parameters, the quick survey of laser parameters is vital. We have developed Yb-doped fiber chirped-pulse amplification system that can control various laser parameters in a wide range (pulse duration: 0.4 to 400 ps, etc.). The laser micro-drilling and imaging under 450 conditions were performed for about 0.5 hour, the 2D mapping of ablation volume with pulse duration and fluence was also accomplished by automatic confocal laser scanning microscopic measurements for several hours. The fast and comprehensive survey of ultrafast laser processing of glasses was demonstrated.

Recently, GHz burst-mode fs laser pulses, which consists of pulse trains with extremely short intervals of several hundred ps, show superior processing characteristics in laser ablation to the conventional femtosecond laser processing (single mode) at the same average power. The GHz bursts of fs laser enables to induce ablation before the residual thermal energy deposited by preceding pulses diffuses away from the processed area, resulting in the reduction of the ablation threshold and enhancement of ablation efficiency. In this study, we apply the GHz burst mode fs laser pulses for MPP of photo-sensitive polymers to explore the effect of the burst on photochemical reaction.

Filamentation induced by femtosecond laser pulses in transparent dielectrics has received much attention due to its potential application prospects in micro processing fields. The processing mechanism is essentially determined by the interaction between femtosecond laser pulses and matters, and subsequent filament properties. However, the evolution characteristics of filaments have not been systematically investigated. Herein, we observed the spatiotemporal evolution of filaments induced by a femtosecond laser pulse in silica glass and sapphire by using time-resolved pump-probe shadowgraphy. The dependence of filament evolution on material properties was analyzed, considering the excitation and decay of electronic plasma. In addition, we conducted experiments under different pump powers and focal depths, to clarify the dependence of filament on laser parameters. This study contributes to the understanding of filamentation mechanism and precise control of micro processing applications.

Here, we demonstrate the first controlled nano-fabrication capability deep inside silicon wafers. We exploit a spatially-structured laser beam and novel fabrication approaches, in order to achieve multi-dimensional nano-confinement inside the bulk. We demonstrate the formation of 100-nm-sized buried structures. We further showcase this new capability with the first fully buried nano-photonic element inside silicon, a Bragg grating. To the best of our knowledge this constitutes the first controlled nano-fabrication capability, as well as the first functional nano-photonic device, created deep inside silicon without any surface alteration.

Our laboratory has reported that periodic micro swelling structures on silicone rubber surfaces are photochemically formed, and the surface has superhydrophobicity. At the conference, the formation of cup-shaped structures on the top of periodic micro swelling structures on silicone rubber surface by 193 nm ArF excimer laser irradiation will be reported. The micro-cup structure is formed by irradiating the silicone rubber with silica microspheres aligned in a single layer with the 193 nm ArF excimer laser. The formation method and the nature of the micro-cup structure will be discussed.

We compare the double-track waveguide lasers inscribed inside Nd:YAG crystals using femtosecond laser pulses at 515 nm and 1030 nm. For both source wavelengths, the highly efficient, continuous wave, single mode and stable lasing at 1064 nm has been achieved in a monolithic cavity formed by the crystal with dielectric coatings at the input and output end facets. In addition to source wavelength, the lasing performance and guiding properties for track separations of 15 µm and 30 µm are compared.

Laser welding can make ceramics integral components in devices for harsh environments as well as in optoelectronic and/or electronic packages needing visible-radio frequency transparency. We will discuss an ultrafast pulsed laser welding approach that relies on focusing light on interfaces to ensure an optical interaction volume in ceramics to stimulate nonlinear absorption processes, causing localized melting rather than ablation. We will begin by comparing laser joining of glasses and ceramics. We will then introduce various methods for controlling the absorption and scattering properties for ceramics because the key to the technique is the interplay between linear and nonlinear optical properties and laser energy–material coupling. Finally, we will discuss results of laser material interaction on various oxide ceramics.

Machining of stainless steel with ultrashort laser pulses is often a challenging task due to heat accumulation problems leading to bumpy surfaces or due to the formation of cavities or cone-like protrusions (CLP) at high pulse energies. With a specific diffractive optical element (DOE) leading to a special beam shape and synchronized scanning a removal rate of 16 mm3/min was achieved on steel AISI 304 with an average power of 180 W and a repetition rate of 1 MHz. Flat and shiny surfaces without CLP's and bumps having a surface roughness of sa < 500 nm were achieved. In case of copper the maximum removal rate amounted 17 mm3/min with a surface roughness of sa < 400 nm at a repetition rate of 400 kHz and an average power of about 150 W. The experiments clearly show, that with beam forming high average powers can be used for high quality laser micromachining with ultrashort laser pulses and single beams at average powers exceeding 100 W.

Ultrafast-laser irradiated surface is a typical paragon of a self-organizing system, which emerge and organize complex micropatterns and even nanopatterns. An astounding exhibition of dissipative structures consists of various types of randomly and periodically generated nanostructures that originate from a homogeneous metal surface. The formation of nanopeaks, nanobumps, nanohumps and nanocavities patterns with 20–80 nm transverse size unit and up to 100 nm height are reported under femtosecond laser irradiation with a regulated energy dose. We shed the light on the originality of the nanopeaks, having an exceptional aspect ratio on the nanoscale. They are primarily generated on the crests grown between the convective cells formed on the very first pulses. The production of these distinct nanostructures can enable unique surface functionalizations toward the control of mechanical, biomedical, optical, or chemical surface properties on a nanometric scale.

Laser microprocessing using Ultra-Short Pulse lasers has developed thanks to the achieved process quality. The main challenge of those processes is the yield improvement. This study will focus on yield improvement of applications such as such as probe card manufacturing for electronic applications with a green USP laser using beam splitting. We present here a fully reflective beam splitter compatible with 500fs green lasers. The compatibility with an industrial machine is demonstrated through a F-theta lens, as well as through a precession head. We show here the process results including the repeatability of the pattern, and the achievable ablation rate.

A method to directly fabricate silver topographies with high fabrication throughput on arbitrary substrates is presented. The method is based on a laser induced photoreduction of a silver precursor and assisted by nucleation seeds, substrate functionalization and a multi-exposure fabrication scheme. In total, the novel photo-sensitive material and the novel fabrication scheme enable effective fabrication speeds of up to a centimeter per second. With this fabrication speed, the fabrication of silver topographies extending over several millimeters – e.g., components working in the THz frequency range - is now feasible and sample applications presented.

A novel method capable of the rapid fabrication of cellulose nanofiber (CNF)-based supercapacitors using a femtosecond laser is demonstrated. When high-repetition femtosecond laser pulses were scanned onto the surface of a CNF film, a black-colored double-tracked structure was fabricated in the vicinity of the laser ablated groove. The black structure exhibited electrical conductivity, and was composed of graphitic carbon. By utilizing the electrically conductive graphitic carbon as electrodes with an electrolyte solution between the groove, the fabricated double-tracked structure exhibited capacitive properties.

Electrically-conductive-porous carbon was fabricated by the laser carbonization of bamboo and applied as the electrodes of a supercapacitor. Scanning electron microscopy revealed that the porosity of the formed structures was higher when slower scanning speeds were used. We fabricated an all-biomass-derived supercapacitor by covering the patterned porous carbon with agarose gel, which functioned as an electrolyte. Supercapacitors that show relatively higher capacitance were fabricated using slower scanning speeds, which could be attributable to a higher porosity of the electrodes. The proposed method is promising for the realization of sustainable energy-storage devices.

In this study, we demonstrated the light-driven control of the flow-rate inside a microchannel within a temperature-responsive hydrogel by fabricating metal microstructures by multiphoton photoreduction. When CW light was illuminated onto the microstructures, significant alteration in the flow-rate was confirmed. The change in flow-rate is attributable to the light-stimulated deformation of the microchannel associated with the shrinkage of the PNIPAm hydrogel. This method allows for the spatially-selective control of the flow-rate simply via light illumination since the light absorbers can be fabricated at a targeted position by multiphoton photoreduction.

Ultrashort pulse laser processing has been proved as an efficient method of microfabricating dielectric materials such as silicon carbide, sapphire, and glass, yet damages are formed around the processed area. In this study, we combine a pump-probe imaging system with a high-speed camera to visualize the ultrafast phenomena of each pulse irradiation and identify the mechanism of damage generation of dielectric materials. In addition, the observations are conducted with various pulse widths to clarify the dependence on the processing conditions. The results demonstrate that the damage is mainly caused by the electron excitation and stress wave propagation.