Functional crystal films fabricated by pulsed laser deposition

Crystalline films grown by epitaxial deposition techniques are typically limited by growth rates to being relatively thin (~ 10 micron thick layers. With these films we have demonstrated the first PLD-grown waveguide lasers with slope efficiencies to 70% and over 20W of output power. The same Yb:Y 3 Al 5 O 12 waveguide has also been used as a double-pass amplifier with 16dB of gain with equivalent output power.Due to the non-thermal-equilibrium conditions exploited in PLD, growth of refractory oxides such as sesquioxides (Lu 2 O 3 , Al 2 O 3 and mixes Lu x Sc y O 3 ) are readily realised, which can also be doped with optically active ions to make active films, suitable for waveguide amplifiers and lasers. Furthermore, controlling the deposition parameters we have precise control of the film’s optical properties, such as refractive index and crystal composition, enabling the production of complex functionalised structures including a dual-core planar waveguide or crystalline Bragg mirrors. Damage thresholds of >30Jcm -2 were obtained from first experiments with a Bragg stack containing 45 garnet layers, which was also operated at temperatures over 700°C.