Excitation of Hermite Gaussian modes in end-pumped solid-state lasers via off-axis pumping

We demonstrate a method for the excitation of Hermite Gaussian modes (one transverse dimension) in end-pumped solid-state lasers. The excitation is performed by pumping off-axis with the help of a fibre-coupled laser diode. With increasing transverse separation of the fibre from the optical axis, the Hermite Gaussian modes can be successively observed. This laser has a variable M2-factor and can therefore be used as an M2-standard in calibration purposes. M2-factors between 1 and 190 are attained with this method.