Abstract Femtosecond laser direct writing is a powerful technique for fabricating micro‐nano devices as it can modify the interior of transparent optical materials in spatially selective manner through nonlinear multi‐photon absorption. In this context, laser‐induced nanogratings, i.e., sub‐wavelength assembly nanolayers (≈20 nm width, ≈200 period), are ultrashort self‐organized structures created by light bulk materials. These have been intensively explored over last two decades opening...

Abstract A type of glass modifications occurring after femto‐second laser irradiation gives rise to strong (10 −2 ) from birefringence. This form birefringence is thought be related index nanostructure (called nanogratings). Analyzing induced tracks in fused silica using scanning electron microscopy (SEM) with nm resolution shows that nanostructures are porous nanoplanes an average lower than typical (Δ n ∼ –0.20). Their origin explained as arising fast decomposition the under localized,...

This review allows better defining the domains of macroscopic effects produced by femtosecond laser irradiation in pure silica according to parameters.

An object that possesses chirality, is, having its mirror image not overlayed on itself by rotation and translation, can provide a different optical response to left- or right-handed circular polarized light. Chiral nanostructures may exhibit polarization-selective properties be controlled for micro-to-nano element engineering. attractive way induce such complex in three-dimension glass is femtosecond laser direct writing. However, the mechanism of induced chirality remains unveiled due...

Waveguides are inscribed through densification of the surrounding region a damage induced channel created by femtosecond irradiation within silica. Single mode propagation at 1.5 μm is obtained below whilst shorter wavelengths guidance only observed away on either side region. The quasi-periodic nanostructure that can explain profile elongation with polarised light 45°. origin this area explored using SEM analysis, which reveals nanoporous regions laser track structure above and densified...

The refractive index changes in doped silica are investigated. We observed that the permanent isotropic change threshold (T1) is not significantly dependent on doping. show strong birefringence (permanent linear birefringence) exists but its (T2) exhibits significant dependence used dopants. In our conditions, comparing with (0.31 μJ/pulse here), for 1.5 at% Ge-doped T2 smaller (0.14 ± 0.05 μJ/pulse). For a 0.3 of fluorine, close to 1.20 μJ/pulse. An interpretation given only about variation...

This paper focuses on the critical role of temperature in ultrafast direct laser writing processes, where changes can trigger or exclusively drive certain transformations, such as phase transitions. It is important to consider both temporal dynamics and spatial distribution for effective control material modifications. We present analytical expressions variations induced by multi-pulse absorption, applicable pulse durations significantly shorter than nanoseconds within a spherical energy...

Laser-induced crystallization in glasses is of great interest because its significant applications optics. However, the mechanisms involved are not yet concluded, and this paper aimed at making progress on problem. Major aspects laser-induced nanostructure formation, textured crystallization, growth dynamics. Lithium niobium silicate were used as a "glass model" to investigate formation by femtosecond (fs) laser irradiation high repetition rate (100–500 kHz). Three regimes can be classified...

Abstract Aluminosilicate glasses offer wide‐ranging potential as enabling materials for a new generation of optical devices operating in harsh environments. In this work, nonconventional manufacturing process, the molten core method, is employed to fabricate and study sapphire (Al 2 O 3 ) YAG (yttrium aluminum garnet) derived all‐glass silicate fibers which femtosecond (fs) laser used imprint oriented nanostructures inside fiber cores. Both writing kinetics thermal stability laser‐modified...

Polarization plays a crucial role in light–matter interactions; hence its overall manipulation is an essential key to unlock the versatility of light manufacturing, especially femtosecond laser direct writing. Existing polarization-shaping techniques, however, only focus on their transverse plane beams, i.e., two-dimensional control. In this paper, we propose novel passive strategy that exploits class written space varying birefringent elements shape polarization state along optical path. As...

Femtosecond (fs) laser irradiation inside transparent materials has drawn considerable interest over the past two decades. More specifically, self-assembled nanogratings, induced by fs direct writing (FLDW) glass, enable a broad range of potential applications in optics, photonics, or microfluidics. In this work, comprehensive study nanogratings formed fused silica FLDW is presented based on high-resolution electron microscopy imaging techniques. These nanoscale investigations reveal that...

We report the structural changes inside germania glass induced by femtosecond laser pulses. Inspection polarization microscopy and secondary electron indicate that periodic nanostructures consist of oxygen defects such as ODC s (oxygen deficient centers) NBOHC (nonbridging hole for pulse energy less than 0.2 μJ. However, network was dissociated O 2 molecules were generated greater 0.4 Two different changes, form‐birefringence dissociation, in GeO glass, depending on energy. The exhibited...

We demonstrate crystals (LiNbO(3)-like) that were space-selectively nucleated and grown in the bulk of silica-based glass by femtosecond laser irradiation at a high repetition rate (typ. 300 kHz). Oriented with their polar axis mostly aligned or perpendicular to scanning direction have been fabricated manipulation temperature gradient adjusting parameters. The mechanism for orientation laser-induced crystallization is briefly discussed.

We explore femtosecond laser-induced modifications (i.e., morphology, crystallization, and nanostructure) in lithium niobium silicate glass at high repetition rates (1030 nm, 300 fs, kHz) to get insight on the ultrafast laser–matter interaction according pulse energy writing configuration (the laser polarization direction versus scanning one). The can be classified into three regimes energy: (1) 0.3–0.4 μJ/pulse, one amorphous zone with a larger sensitivity chemical etching; (2) 0.5–0.9...

It is demonstrated that the form birefringence related to so-called nanogratings quantitatively correlated porosity-filling factor of these nanostructures. We reveal matters surrounding nanopores exhibit significant refractive index decrease which likely due fictive temperature increase and/or presence a amount interstitial O2. The control porosity was achieved by adjusting laser pulse energy and number pulses/micron i.e. overlapping rate. Applications can be numerous in fast material...

Understanding the phase transformation in glass and morphology of related nanostructure after femtosecond laser irradiation is great importance for fabricating functional optics, which crystallization involved to obtain nonlinear optical properties. We report on inside lithium niobium silicate induced by fs irradiation. Energy‐dispersive X‐ray spectroscopy coupled scanning transmission electron microscopy ( STEM / EDS ) confirm a nanoscale separation whereby LiNbO 3 crystals are embedded...

Type II modifications induced by infrared (IR) femtosecond (fs) lasers are used in many optical devices due to their excellent thermal stability at high temperatures (typically >800 °C). The characteristic feature of type is the formation nanogratings, which easily detected through birefringence measurements. However, measured an aggregate value multiple contributions including form birefringence, stress‐induced permanent volume changes, and point defects. This work investigates erasure...

The thermal stability of self-assembled porous nanogratings inscribed by an infrared femtosecond (fs) laser in five commercial glasses (BK7, soda lime, 7059, AF32, and Eagle XG) is monitored using step isochronal annealing experiments. Their erasure, ascertained retardance measurements attributed to the collapse nanopores, well predicted from Rayleigh-Plesset (R-P) equation. This finding thus employed theoretically predict erasure context any time-temperature process (e.g., annealing,...

This study explores the structural transformations induced by femtosecond (fs) laser inscriptions in glass, with a focus on type II modifications (so-called nanogratings), crucial for advanced optical and photonic technologies. Our novel approach employs scattering-type scanning near-field microscopy (s-SNOM) synchrotron radiation nanoscale Fourier-transform infrared spectroscopy (nano-FTIR) to directly assess changes tracks, potentially offering comprehensive understanding of underlying...