  We demonstrated fabrication of waveguide and directional coupler in bulk
glass-ceramics Zerodur, through femtosecond laser direct-writing. Waveguide
propagation loss of no more than 1.5 dB/cm was achieved. We expect this will
lead to the deployment of Zerodur integrated photonics in fields like
space-borne astronomy, quantum technology and fundamental physics, for both
economic and technical benefits.
