Abstract

Femtosecond lasers are widely used nowadays for three-dimensional volume micro-structuring of dielectric materials since the technique was first demonstrated in 1996 [1]. The femtosecond laser direct-write technique has already been successfully utilised to create waveguides written in active glasses that incorporate Bragg gratings to form the basis of a stable, monolithic waveguide laser platform [2]. Dielectric crystalline offers many advantages over a glass host such as high optical gain, high damage threshold and high thermal conductivity. In particular, channel waveguides (based on a stress induced refractive index change) fabricated in Yb:YAG are suitable for efficient waveguide lasers. In this crystalline system, laser gain is extremely high, allowing laser operation to be achieved by Fresnel reflections at sample end faces rather than using external mirrors. To date, slope efficiencies >75% and output powers >1 W (measured by summing the output exiting from both ends of the chip) have been demonstrated [3].

© 2015 IEEE