Pulsed laser deposition of Yb:Y₂O₃ planar waveguide lasers

Parsonage, T.L., Beecher, S.J., Sloyan, K., Mackenzie, J.I. and Eason, R.W. (2014) Pulsed laser deposition of Yb:Y₂O₃ planar waveguide lasers. Materials Research Society Spring Meeting E-MRS '14, , Lille, France. 26 - 30 May 2014.

Abstract

Rare earth-doped sesquioxides, particularly yttria (Y₂O₃), scandia (Sc₂O₃) and lutetia (Lu₂O₃), are very promising materials for high power laser applications due to their excellent combination of thermal, optical and spectroscopic properties. These simple cubic crystals have been successfully doped with rare earth elements such as Yb, Tm and Er, but are challenging to grow as bulk crystals, due to their high melting points (~2400°C).
Using pulsed laser deposition, we have grown both single and multilayer Yb-doped crystalline yttria waveguides on 1 cm² YAG substrates. A multilayer sample with a 3 µm Y₂O₃ layer either side of a 6 µm Yb:Y₂O₃ doped region gave a maximum output power of 1.2 W at 1030 nm, for ~10.5 W of diode pump power. This waveguide design provides significantly higher gain for the fundamental waveguide mode than for higher order modes, enabling efficient multimode pumping whilst favouring diffraction limited output. The maximum observed slope efficiency was 22% (with respect to absorbed power), using a simple quasi-monolithic plane-plane resonator cavity with a 30%R output coupler. With no active cooling, even at these high pump powers, no sign of thermal effects in the waveguide have been observed, confirming the excellent thermal properties of this material.
We will discuss these first results together with further experiments that will be performed with an optimised cavity length to achieve higher output power, lower threshold and greater slope efficiency.

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Contributors

Author: J.I. Mackenzie

Author: R.W. Eason

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