High-power fibre-laser-pumped Er:YAG laser with ‘top-hat’ output beam

Here, we report simple technique for efficiently generating a top-hat output beam with excellent beam quality in an end-pumped solid-state laser. Our approach is based on using a pump beam with a specially tailored beam profile to selectively excite both the first-order Laguerre-Gaussian mode (LG₀₁) and fundamental Hermite Gaussian mode (TEM₀₀) with the appropriate relative powers, so that the resultant beam has a near top-hat beam profile. We have applied this technique to a hybrid (fibre-laser-pumped) E:YAG laser operating at 1645 nm.