This invention generally relates to semiconductor devices, for example lasers and more particularly to single frequency lasers and is directed at overcoming problems associated with the manufacture of these devices. In particular, a laser device is provided formed on a substrate having a plurality of layers (1,2,3,4,5), the laser device comprising at least one waveguide (for example a ridge) established by the selective removal of sections of at least one of the layers. Wherein alignment features are provided on the device to facilitate subsequent placement.