Ultrafast Filamentary Excitation Process in Glass During Bessel Beam Irradiation

Glass substrates have gained significant attention as key materials in next-generation semiconductor packages due to their excellent mechanical properties and low thermal expansion. Among advanced fabrication techniques, the use of Bessel beam shaped ultrashort pulsed lasers has shown remarkable advantages, including non-diffractive propagation and deep processing capabilities [1]. This method is also employed in the Laser Induced Deep Etching (LIDE) process [2], [3], where forming uniform electron excitation regions within the material is critical. However, the mechanisms governing the formation of such regions remain inadequately understood, necessitating further investigation.