in an internal combustion engine with externally supplied ignition , the compressed air - fuel mixture is ignited , at least partially , with the use of at least one laser beam , which is introduced into a combustion chamber via at least one optical waveguide and is focused onto an ignition location . in order to achieve a simple and compact design , the optical waveguide is positioned in a sealing element bounding the combustion chamber , wherein the sealing element is located in a cutting plane through the combustion chamber and preferably is constituted by a cylinder head gasket .