A laser (2) includes a gain medium (10), a switch element (12) and a pulse controller (14). In one embodiment laser light of differing polarisations pass along respective paths and a pulsed laser output is generated via an electro-optical element. In another embodiment light of differing polarisations passes in differing directions through a cylical path. The invention can make use of a prism-shaped polariser having a polarisation selection face and two further faces. Yet further initial pulses can be controlled to reduce energy for example by progressively increasing the period or amplitude of successive pulses. As a result an efficient and high power laser apparatus is realised.