Ultrafast-Laser-Induced Tailoring of Crystal-in-Glass Waveguides by Precision Partial Remelting.

Space-selective laser-induced crystallization of glass enables direct femtosecond laser writing of crystal-in-glass channel waveguides having nearly single-crystal structure and consisting of functional phases with favorable nonlinear optical or electrooptical properties. They are regarded as promising components for novel integrated optical circuits. However, femtosecond-laser-written continuous crystalline tracks typically have an asymmetric and strongly elongated cross-section, which causes a multimode character of light guiding and substantial coupling losses.

Effect of Pulse Repetition Rate on Ultrafast Laser-Induced Modification of Sodium Germanate Glass.

We report an unexpected pulse repetition rate effect on ultrafast-laser modification of sodium germanate glass with the composition 22NaO 78GeO. While at a lower pulse repetition rate (~≤250 kHz), the inscription of nanogratings possessing form birefringence is observed under series of 10-10 pulses, a higher pulse repetition rate launches peripheral microcrystallization with precipitation of the NaGeO phase around the laser-exposed area due to the thermal effect of femtosecond pulses via cumulative heating. Depending on the pulse energy, the repetition rate ranges corresponding to nanograting formation and microcrystallization can overlap or be separated from each other.

Multilevel data writing in nanoporous glass by a few femtosecond laser pulses.

Multidimensional data recording inside nanoporous high-silica glass by a femtosecond laser beam has been investigated. It is shown that three femtosecond laser pulses at pulse repetition rates up to 1 MHz are sufficient for recording 3 bits of information inside nanoporous glass, which is an order of magnitude lower than the number of pulses required for data writing in silica glass and provides a corresponding gain in the data writing speed. Multilayer data recording and reading were demonstrated providing the storage density corresponding to the capacity of 25 GB in the optical compact disc form factor.

Spatially selective Au nanoparticle growth in laser-quality glass controlled by UV-induced phosphate-chain cross-linkage.

Herein we describe how UV excitation of localized electronic states in phosphate glasses can activate structural rearrangements that influence the kinetics of Au nanoparticle (NP) thermal growth in Au-doped glass. The results suggest a novel strategy to address the problem of controlling nano-assembly processes of metal NP patterns in fully inorganic and chemically stable hard materials, such as laser-quality glasses. We show that the mechanism is promoted by opening and subsequent cross-linkage of phosphate chains under UV excitation of non-bridging groups in the amorphous network of the glass, with a consequent modification of Au diffusion and metal NP growth.