Ultrafast laser direct-write inscription of monolithic fibre and waveguide lasers

The use of a scanned femtosecond laser focus to create optical waveguide devices is an established and powerful technique with applications in sensing and quantum information. Using a sub-surface focussed femtosecond laser, a dielectric material can be modified at a highly localised point without surrounding material modification. By controlling the laser-photonic material interactions and fabrication parameters, a permanent change in the refractive index of the material can be achieved. Not only can this direct-write technique be carried out rapidly, it is readily compatible with existing fibre systems, it does not require a lithographic mask and it can be conducted in a regular laboratory environment with the minimum of sample preparation.