Ultrafast Laser Induced Structural Modification of Fused Silica—Part II: Spatially Resolved and Decomposed Raman Spectral Analysis

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Siniša Vukelić ◽  
Panjawat Kongsuwan ◽  
Sunmin Ryu ◽  
Y. Lawrence Yao
Keyword(s):  
Femtosecond Laser ◽  
Structural Changes ◽  
Volume Fraction ◽  
Random Network ◽  
Target Material ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Process Conditions ◽  
Spatially Resolved

Nonlinear absorption of femtosecond laser pulses enables the induction of structural changes in the interior of bulk transparent materials without affecting their surface. In the present study, femtosecond laser pulses were tightly focused within the interior of bulk fused silica specimen. Localized plasma was formed, initiating rearrangement of the random network structure. Cross sections of the induced features were examined via decomposition of spatially resolved Raman spectra and a new method for the quantitative characterization of the structure of amorphous fused silica was developed. The proposed method identifies the volume fraction distribution of ring structures within the continuous random network of the probed volume of the target material and changes of the distribution with laser process conditions. Effects of the different process conditions and the material response to different mechanisms of feature generation were discussed as well.

Ultrafast Laser Induced Structural Modification of Fused Silica—Part I: Feature Formation Mechanisms

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Siniša Vukelić ◽  
Panjawat Kongsuwan ◽  
Y. Lawrence Yao
Keyword(s):  
Femtosecond Laser ◽  
Material Properties ◽  
Structural Changes ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Optical Data ◽  
Formation Mechanisms ◽  
Force Microscopy

Nonlinear absorption of femtosecond-laser pulses enables the induction of structural changes in the interior of bulk transparent materials without affecting their surface. This property can be exploited for transmission welding of transparent dielectrics, three dimensional optical data storages, and waveguides. In the present study, femtosecond-laser pulses were tightly focused within the interior of bulk fused silica specimen. Localized plasma was formed, initiating rearrangement of the network structure. Features were generated through employment of single pulses as well as pulse trains using various processing conditions. The change in material properties were studied through employment of differential interference contrast optical microscopy and atomic force microscopy. The morphology of the altered material as well as the nature of the physical mechanisms (thermal, explosive plasma expansion, or in-between) responsible for the alteration of material properties as a function of process parameters is discussed.

Characterization of Morphology and Mechanical Properties of Glass Interior Irradiated by Femtosecond Laser

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Panjawat Kongsuwan ◽  
Hongliang Wang ◽  
Sinisa Vukelic ◽  
Y. Lawrence Yao
Keyword(s):  
Mechanical Properties ◽  
Femtosecond Laser ◽  
Welding Process ◽  
Laser Pulses ◽  
Structural Rearrangement ◽  
Processing Parameters ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Element Analysis ◽  
Spatially Resolved

Femtosecond laser pulses were focused in the interior of a single fused silica piece. Proper use of optical and laser processing parameters generated structural rearrangement of the material through a thermal accumulation mechanism, which could be potentially used for the transmission welding process. The morphology of generated features was studied using differential interference contrast optical microscopy. In addition, the predictive capability of the morphology is developed via a finite element analysis. The change in mechanical properties was studied through employment of spatially resolved nanoindentation. The specimen was sectioned and nanoindents were applied at the cross section to examine mechanical responses of the laser-modified region. Fracture toughness measurements are carried out to investigate the effects of the laser treatment on strength of the glass.

Structural Modification of Amorphous Fused Silica Under Femtosecond Laser Irradiation

2008 ◽  
Author(s):  
S. Vukelic ◽  
B. Gao ◽  
S. Ryu ◽  
Y. L. Yao
Keyword(s):  
Femtosecond Laser ◽  
Material Properties ◽  
Structural Changes ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Femtosecond Laser Irradiation ◽  
Optical Data ◽  
Linear Absorption

Non-linear absorption of femtosecond laser pulses enables the induction of structural changes in the interior of bulk transparent materials without affecting their surface. This property can be exploited for the transmission welding of transparent dielectrics, three dimensional optical data storages and waveguides. In the present study, femtosecond laser pulses were tightly focused within the interior of bulk fused silica specimen. Localized plasma was formed, initiating rearrangement of the network structure. The change in material properties were studied through employment of spatially resolved Raman spectroscopy, atomic force microscopy and optical microscopy. The nature of the physical mechanisms responsible for the alteration of material properties as a function of process parameters is discussed.

Structural changes in fused silica after exposure to focused femtosecond laser pulses

2001 ◽  
Vol 26 (21) ◽  
pp. 1726 ◽  
Author(s):  
J. W. Chan ◽  
T. Huser ◽  
S. Risbud ◽  
D. M. Krol
Keyword(s):  
Femtosecond Laser ◽  
Structural Changes ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica

High power supercontinuum generation by dual-color femtosecond laser pulses in fused silica

2021 ◽  
Author(s):  
Saba Zafar ◽  
Dong-Wei Li ◽  
Acner Camino ◽  
Jun-Wei Chang ◽  
Zuo-Qiang Hao
Keyword(s):  
Femtosecond Laser ◽  
High Power ◽  
Microlens Array ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Spectral Energy ◽  
Phase Matching ◽  
Fundamental Wavelength ◽  
Fundamental Laser

Abstract High power supercontinuum (SC) is generated by focusing 800 nm and 400 nm femtosecond laser pulses in fused silica with a microlens array. It is found that the spectrum of the SC is getting broader compared with the case of single laser pulse, and the spectral energy density between the two fundamental laser wavelengths is getting significantly higher by optimizing the phase matching angle of the BBO. It exceeds μJ/nm over 490 nm range which is from 380 nm to 870 nm, overcoming the disadvantage of relative lower power in the ranges far from fundamental wavelength.

Transient reflectivity and transmission changes during plasma formation and ablation in fused silica induced by femtosecond laser pulses

2008 ◽  
Vol 92 (4) ◽  
pp. 803-808 ◽  
Author(s):  
D. Puerto ◽  
W. Gawelda ◽  
J. Siegel ◽  
J. Bonse ◽  
G. Bachelier ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica ◽  
Plasma Formation

Enhanced formation of nanogratings inside fused silica due to the generation of self-trapped excitons induced by femtosecond laser pulses

2012 ◽  
Author(s):  
Sören Richter ◽  
Fei Jia ◽  
Matthias Heinrich ◽  
Sven Döring ◽  
Stefan Nolte ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Fused Silica

Fabrication of Anisotropic Structures on the Surface of Amorphous Silicon by Femtosecond Laser Pulses

2020 ◽  
Vol 312 ◽  
pp. 192-199
Author(s):  
Dmitrii V. Shuleiko ◽  
Mikhail N. Martyshov ◽  
Danila V. Orlov ◽  
Denis E. Presnov ◽  
Stanislav V. Zabotnov ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Femtosecond Laser ◽  
Volume Fraction ◽  
Film Surface ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Surface Structures ◽  
Radiation Polarization ◽  
Direction Parallel ◽  
Nanocrystalline Si

Anisotropic periodic relief in form of ripples was formed on surface of amorphous hydrogenated silicon (a-Si:H) films by femtosecond laser pulses with the wavelength of 1.25 μm. The orientation of the surface structures relative to laser radiation polarization vector depended on the number of laser pulses N acting on the film surface. When N = 30, the structures with 0.88 μm period were formed orthogonal to the laser radiation polarization; at N = 750 the surface structures had period of 1.12 μm and direction parallel to the polarization. The conductivity of the laser-modified a-Si:H films increased by 3 to 4 orders of magnitude, up to 3.8·10–5 (Ω∙cm)–1, due to formation of nanocrystalline Si phase with a volume fraction from 17 to 30%. Anisotropy of the dark conductivity, as well as anisotropy of the photoconductivity spectral dependences was observed in the modified films due to depolarizing influence of periodic microscale relief and uneven distribution of nanocrystalline Si phase within such laser-induced structure.

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