A laser apparatus has a gain medium which has opposite ends, wherein the laser apparatus includes at least two independently controllable excitation sources, each one of the excitation sources being operable to produce an input beam to excite or pump the gain medium. Beam splitting arrangements are associated with the excitation sources are configured to split the input beam of its associated excitation source into at least two sub-beams. Beam guiding arrangements are associated with the excitation sources and are configured to direct a path of at least one of the split sub-beams from its associated excitation source, whereby each excitation source, its associated beam splitting arrangement, and beam guiding arrangement are arranged such that the sub-beams are respectively directed inwardly towards the gain medium at opposite ends.