This invention relates to the field of lasers and in particular to the pump sources used in lasers. Many existing lasers use linear flashlamps in order to create population inversion in the gain medium of the laser. Such pump sources suffer from a number of drawbacks particularly when pumping dye lasers including explosive damage, long optical pulse length and inappropriate spectral emission. This invention provides a pump source for a laser which exploits the surface discharge phenomenon. A dielectric material (1) which is in contract with a gas (9) has electrical energy discharged across its surface in order to provide an electromagnetic emission which is then used to pump the gain medium. By varying the dielectric material or the cover gas used (amongst other variables) the surface emission can be used to pump the laser gain medium.