Laser micromachining of phononic crystals and waveguides in borosilicate glass

Fabrication of phononic crystals (PnCs) in borosilicate glass is demonstrated through laser microfabrication with a nanosecond pulsed laser at a wavelength of 515 nm. PnC and waveguide structures are produced in 6.35 mm thick (1/4 in.) plates of Duran® glass. The phononic bandgap of the fabricated crystal, centered near 200 kHz, is measured in both in-plane and out-of-plane modes and shown to closely agree with finite element analysis (FEA) performed using COMSOL Multiphysics®. A phononic waveguide is similarly produced and characterized by imaging the velocity field along the waveguide channel using a scanning laser Doppler vibrometer, and its guiding properties are found to be in good agreement with the corresponding FEA prediction. This study provides a proof of concept for one-step laser microfabrication of PnCs in dielectric glass substrates using a commercial industrial laser machining platform. The presented concept opens a direct route toward integrated acoustic functions on glass, a substrate class increasingly adopted in the semiconductor industry.