Self‐Organized Periodic Crystallization in Unconventional Glass Created by an Ultrafast Laser for Optical Attenuation in the Broadband Near‐Infrared Region

Abstract The construction of functional photonic structures in transparent solids for various applications, such as 3D displays, optical information processing, and tunable lasers, is of great scientific and technological importance. Here, self‐assembled crystallite‐based grating nanostructures are created in an unconventional multicomponent glass with an ultrafast laser. The novel nanogratings are organized as periodically assembled crystalline and amorphous phases, exhibiting strong polarization‐dependent birefringence. The Ta₂O₅ component in the glass strongly contributes to the creation of nanogratings. Furthermore, a picosecond laser rather than a femtosecond laser is established to more suitably create nanogratings in the target glass, proving the critical role of thermal accumulation during nanoscale crystallization. Finally, nanogratings are demonstrated to be broadband variable near‐infrared optical attenuators with a high attenuation ratio, indicating the potential application of nanogratings in optical information processing at communication wavelengths. These findings provide new directions for fabricating nanogratings in functional glasses for advanced integrated photonics and offer information for revealing the mechanism of nanograting formation.