scholarly journals Passive Q-switch laser operation of circular, buried depressed-cladding waveguides realized by direct fs-laser beam writing in Nd:YAG/Cr^4+:YAG composite media

2017 ◽  
Vol 7 (7) ◽  
pp. 2496 ◽  
Author(s):  
Gabriela Croitoru (Salamu) ◽  
Florin Jipa ◽  
Nicolaie Pavel
Keyword(s):  
Laser Beam ◽  
Laser Operation ◽  
Composite Media ◽  
Fs Laser

Fabrication and Characterization of Si Nano-Columns by Femtosecond Laser

2012 ◽  
Vol 16 ◽  
pp. 15-20 ◽  
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.

Micro and Nanofabrication of GaN by Wet-Chemical-Assisted Femtosecond Laser Ablation

2009 ◽  
Author(s):  
Seisuke Nakashima ◽  
Koji Sugioka ◽  
Katsumi Midorikawa
Keyword(s):  
Laser Ablation ◽  
Laser Beam ◽  
Second Harmonic ◽  
Single Pulse ◽  
Photon Absorption ◽  
Light Extraction Efficiency ◽  
Objective Lens ◽  
Uniform Size ◽  
Fs Laser ◽  
Wet Chemical

For micro/nanofabrication of Gallium nitride (GaN), we developed wet-chemical-assisted fs laser ablation in which the femtosecond (fs) laser beam focused using an objective lens was directed on the surface of a GaN substrate immersed in 35% hydrochloric (HCl) acid solution. Nanocrators with a diameter as small as 320 nm (FWHM) were successfully formed on surface of a single-crystal GaN substrate by a single pulse of the second harmonic fs-laser beam (λ = 387 nm, 150 fs) focused using an objective lens with NA of 0.5. Nano scale ablation is responsible for two-photon absorption of the fs laser. The ablated craters exhibit higher quality and better uniformity with little debris formation compared with those produced by fs-laser ablation in air followed by etching in HCl (two-step processing method). The high quality ablation is presumably due to photochemical or photothermal reaction of HCl solution with ablated materials, resulting in complete removal of debris and in sharp edge and smooth surface of craters. We have demonstrated formation of 140-μm-long straight and hollow channels embedded in GaN by scanning the laser beam inside the substrate. 3D micro and nano fabrication technique of GaN has great potential for manufacture of highly-functional micro devices. We have also tried to fabricate 2D periodic nanostructures on GaN surface by scanning the sample in x-y plane. Nanocrators with uniform size periodically arranged on GaN surface can act as a two-dimensional (2D) photonic crystal which is expected to enhance a light extraction efficiency of blue LED.

scholarly journals Formation and applications of periodic structures in transparent materials induced by single fs laser beam

2013 ◽  
Vol 3 (11) ◽  
pp. 1944 ◽  
Author(s):  
Fangteng Zhang ◽  
Yu Teng ◽  
Yongze Yu ◽  
Kaniyarakkal N. Sharafudeen ◽  
Kazuyuki Hirao ◽  
...  
Keyword(s):  
Laser Beam ◽  
Periodic Structures ◽  
Fs Laser ◽  
Transparent Materials

PHOTONIC PATTERN FABRICATION IN FUSED SILICA, BK7, ANDGe-DOPED BOROPHOSPHOSILICA GLASS BY A FEMTOSECOND LASER

2005 ◽  
Vol 14 (03) ◽  
pp. 305-309
Author(s):  
G. J. LEE ◽  
Y. H. JEONG ◽  
J. J. LEE ◽  
C. H. OH ◽  
E. K. KIM ◽  
...  
Keyword(s):  
Laser Beam ◽  
Defect Formation ◽  
Fused Silica ◽  
Photon Absorption ◽  
Circular Cavity ◽  
Absorption Process ◽  
First Order ◽  
Fs Laser ◽  
Refractive Index Grating ◽  
Made In

Photonic patterns were fabricated in fused silica, BK7, and Ge -doped borophosphosilica glass ( Ge -BPSG) using a focused femtosecond (fs)-laser beam. By focusing tens to hundreds of μJ fs-laser beam with a 10x microscope objective, we inscribed the semi-circular cavity patterns on the fused silica and the BK7. The inscribed hole diameters are 28 μm (fused silica) and 11 μm (BK7) at an input fluence of 71 J/cm2. This circular-cavity patterning is ascribed to the ablation via the multi-photon absorption process. For the application to functional devices, the surface relief gratings (SRGs) were made in fused silica and BK7 by focusing the fs-laser beam on the glass surface with a cylindrical lens and by translating the sample in the direction perpendicular to the focus line. The first-order diffraction efficiencies of the prepared SRGs are 34% (fused silica) and 14% (BK7). A refractive-index grating was also fabricated in the Ge -BPSG by using the two-beam interference method. The maximum index modulation of 2.5 × 10-3was obtained for 20,000 laser shots of 73 mJ/cm2per pulse. It is thought that the index modification occurs through the defect formation by the fs-laser irradiation.

Three-dimensional structuring inside transparent materials by a phase modulated fs laser beam with a LCOS-SLM

2011 ◽  
Author(s):  
Masaaki Sakakura ◽  
Kiyotaka Miura ◽  
Tsutomu Sawano ◽  
Yasuhiko Shimotsuma ◽  
Kazuyuki Hirao
Keyword(s):  
Laser Beam ◽  
Three Dimensional ◽  
Fs Laser ◽  
Transparent Materials

scholarly journals Luminescence of Femtosecond Laser-Processed ZnSe Crystal

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Igor Dmitruk ◽  
Nataliya Berezovska ◽  
Volodymyr Degoda ◽  
Yevhen Hrabovskyi ◽  
Roman Kolodka ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Beam ◽  
Single Crystal ◽  
Visible Region ◽  
High Spatial Frequency ◽  
Structural Defects ◽  
Beam Polarization ◽  
Central Wavelength ◽  
Fs Laser ◽  
Znse Single Crystal

The ZnSe single crystal treatment in air environment with linearly polarized Ti/sapphire femtosecond (fs)laser pulses of the energy density of around 0.04-0.05 J/cm2 with central wavelength of 800 nm and the pulse duration of 140 fs at a repetition rate of 1 kHz generates the laser-induced periodic surface structures (LIPSSs). The setup with a cylindrical quartz lens at normal incidence allowed processing a relatively large area of the ZnSe sample in one pass of the laser beam. Morphology analysis of LIPSS by scanning electron microscopy (SEM) and image processing reveals the existence of two periods of around 200.0 nm and 630.0 nm simultaneously. All LIPSSs demonstrate the orientation perpendicular to the laser beam polarization. The possible nature of LIPSS formation on ZnSe single crystal is caused by the synergetic influence of the interference mechanism involving surface plasmon polaritons and hydrodynamic effects of surface morphology modification. The fs-laser-induced changes of carrier concentrations in ZnSe specify obtained periods of high spatial frequency LIPSS. The influence of femtosecond laser processing on luminescent properties of ZnSe single crystal has been studied by an analysis of the photoluminescence (PL) and X-ray luminescence (XRL) spectra of laser-treated and untreated areas in the visible region of spectrum at room and low temperatures. The PL spectra and XRL spectra, as well as temperature dependencies of XRL spectra or thermally stimulated luminescence curves, demonstrate a good correlation for untreated and fs-laser-treated ZnSe surfaces. Specific PL bands related to the extended structural defects do not appear for LIPSS at the ZnSe sample under an excitation of 337 nm (3.68 eV). The Relative intensities and position of separate components of observed luminescence bands after ultrashort laser treatment do not change significantly. Thus, the structural perfection of the ZnSe single crystal surface is preserved.

scholarly journals Influence of scanning speed on TLIPSS formation with axially symmetric and elliptical Gaussian fs laser beam

2018 ◽  
Vol 3 ◽  
pp. 157-172 ◽  
Author(s):  
A Dostovalov ◽  
V Terentyev ◽  
K Bronnikov ◽  
D Belousov ◽  
V Korolkov
Keyword(s):  
Laser Beam ◽  
Scanning Speed ◽  
Axially Symmetric ◽  
Fs Laser

Fabrication of Optical Microlenses in Glass Using a Femtosecond Laser for LBA-on-a-Chip Applications

2006 ◽  
Author(s):  
Y. Cheng ◽  
H. L. Tsai
Keyword(s):  
Femtosecond Laser ◽  
Laser Beam ◽  
Chemical Etching ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Lab On A Chip ◽  
Selective Removal ◽  
Curved Surfaces ◽  
Photosensitive Glass ◽  
Fs Laser

We describe the fabrication of microoptical cylindrical and hemispherical lenses vertically embedded in a photosensitive Foturan glass by femtosecond (fs) laser three-dimensional (3D) micromachining. The process is mainly composed of four steps: (1) fs laser scanning in the photosensitive glass to form curved surfaces (spherical and/or cylindrical); (2) postannealing of the sample for modification of the exposed areas; (3) chemical etching of the sample for selective removal of the modified areas; and (4) second postannealing for smoothening the surfaces of the tiny lenses. We examine the focusing ability of the microoptical lenses using a He-Ne laser beam, showing great potential of using these microoptical lenses in lab-on-a-chip applications.

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