Electrostatic Interpretation of Phase Separation Induced by Femtosecond Laser Light in Glass (original) (raw)
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On the Formation of Nanogratings in Commercial Oxide Glasses by Femtosecond Laser Direct Writing
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Nanogratings (NGs) are self-assembled subwavelength and birefringent nanostructures created by femtosecond laser direct writing (FLDW) in glass, which are of high interest for photonics, sensing, five-dimensional (5D) optical data storage, or microfluidics applications. In this work, NG formation windows were investigated in nine commercial glasses and as a function of glass viscosity and chemical composition. The NG windows were studied in an energy—frequency laser parameter landscape and characterized by polarizing optical microscopy and scanning electron microscopy (SEM). Pure silica glass (Suprasil) exhibits the largest NG window, whereas alkali borosilicate glasses (7059 and BK7) present the smallest one. Moreover, the NG formation windows progressively reduced in the following order: ULE, GeO2, B33, AF32, and Eagle XG. The NG formation window in glasses was found to decrease with the increase of alkali and alkaline earth content and was correlated to the temperature dependence...
Modifications in Glass Induced by Femtosecond Laser Radiation
2014
The interaction of laser radiation with glass becomes nonlinear, when the electric eld strength of a femtosecond laser exceeds the dielectric eld strength of the glass. This eect can lead to a possible void formation along which the material can be precisely shaped. The parameter range of the laser-matter interaction was studied in order to nd the optimal parameters for creating 3D void structures.
Asymmetric Orientational Writing in glass with femtosecond laser irradiation
We review the question on the origin of the differences observed on various properties when we scan the femtosecond laser beam in an isotropic media (i.e. a glass) in two orientations of a given direction. Publications on refractive index changes, birefringence, nanogratings, stress, bubbles formation and on quill writing effects are analyzed. A new interpretation based on space-charge built from ponderomotive force and stored in the dielectric inducing an asymmetric stress field is proposed. "Fabrication of microchannels in glass using focused femtosecond laser radiation and selective chemical etching," Appl. Phys., Optical second-harmonic generation in atomic vapors with focused beams," Phys. Rev. A 23(6), 3139-3151 (1981). 31. M. Lancry, E. Régnier, and B. Poumellec, "Fictive temperature in silica-based glasses and its application to optical fiber manufacturing," Prog.
Space-selective phase separation was induced inside Na 2 O-SiO 2 glasses by changing the glass composition locally from a miscible composition to an immiscible one via femtosecond-laser irradiation at a high repetition rate. The formation of a nanoscale co-continuous structure due to phase separation was confirmed by scanning electron microscopy after heat treatment, polishing until the lasermodified area was exposed, and subsequent etching. The configuration of the structure could be controlled by changing the heat-treatment time.
physica status solidi (a), 2021
The Type II modifications induced by IR femtosecond (fs) laser are used in many optical devices due to their excellent thermal stability at high temperatures (typically> 800 °C). The characteristic feature of Type II modifications is the formation of nanogratings, which can easily be detected through birefringence measurements. However, the measured birefringence is an aggregate value of multiple contributions that include form birefringence, stress-induced birefringence due to permanent volume changes, and point defects. In this work, we investigate the thermal erasure kinetics for each one of these contributions in silica glass. Firstly, we irradiate silica glass samples with a fs-laser using different conditions (polarization, energy). Secondly, we perform accelerated aging experiments to evaluate the stability of the laser-induced modifications, including defects, densification, stress field and porous nanogratings. Finally, the aforementioned contributions to the thermal stability of the nanogratings are identified and discussed using spectroscopic techniques (Raman and Rayleigh scattering, UV-Vis absorption) and electron microscopy. Moreover, porous nanogratings erasure kinetic is simulated using the Rayleigh-Plesset (R-P) equation. This work provides a valuable framework in the realization of silica glass-based optical devices operating at high temperatures (>>800 °C) by 1) evidencing the effect of annealing on each erasure mechanism and 2) providing information on the optical response (mainly the birefringence) upon annealing.