Synthesis and Multiscale Evaluation of LiNbO₃‐Containing Silicate Glass‐Ceramics with Efficient Isotropic SHG Response

Abstract

A study of bulk second harmonic generation (SHG) response of lithium niobium silicate glass‐ceramics is presented. The observed macroscopic SHG signals have an isotropic 3D nature. To interpret this particular nonlinear optical response, a multiscale approach is used in which clear correlations between structure and optical response are characterized from the sub‐micrometer to the millimeter scale. In particular, it is inferred that the radial distribution of the LiNbO3 crystallites in spherulite domains is at the origin of the isotropic bulk second order optical property. It is suggested that spherulitic crystallization in glass‐ceramic is a challenging method to elaborate isotropic nonlinear optical properties in inorganic materials.

Second harmonic generation in germanotellurite bulk glass‐ceramics

“…These analyses were performed using a Spectra Physics Nd:YAG laser 1064 nm, 20 Hz, 20 ns pulses with a typical energy of 250 μJ. More details can be found elsewhere …”

“…The set‐up for micro‐SHG measurement is a modified micro‐Raman (HR 800, HORIBA Jobin Yvon SAS) instrument equipped with a picosecond laser at 1064 nm for SHG measurement. The confocal microscope and motorized stages (X, Y, Z) allow SHG measurements in the bulk of the samples …”

“…Optical glass‐ceramics require high transparency and high SON . To ensure the quality of the transmission in glass‐ceramics, two common solutions are envisaged: size restriction of crystals and/or reduction of the refractive index difference between the glass and the crystallized parts .…”

Transparent niobate glass‐ceramics for optical limiting

“…For the glass‐ceramics sample heat‐treated at 620°C, the diffraction patterns in XRD can be well indexed to LiNbO 3 crystalline phase (PDF 01‐074‐2240). The controllable precipitation of LiNbO 3 crystalline phase inside glass has been reported in several references . Further enhancement of heat‐treatment temperature leads to the appearance of another characteristic peak at 25.5° which is originated from β‐SiO 2 (PDF 01‐081‐1665).…”

“…The result indicates that NbO 6 octahedra are randomly distributed in the glass matrix and this disordered state is formed in the process of the high‐temperature melting‐quenching (Figure B). In stark contrast, the glass‐ceramics exhibit several fingerprint Raman scattering peaks, which are associated with the vibrations of NbO 6 octahedra within a three dimensional niobate network in the LiNbO 3 crystalline phase (Figure B) . It was supposed that the observed unique clustering of NbO 6 octahedra induced by in situ phase transition is highly favorable for enhancing the light‐matter interaction, resulting in the notable increase in the TPA coefficient.…”