Abstract: The present invention relates to solid state distributed feedback (DFB) lasers in which a phase shift is introduced to optical radiation circulating in a laser cavity in order to stabilise the laser into single mode operation. A solid state single mode distributed feedback (DFB) laser (1), comprises a laser waveguide (10), a DFB grating structure (6) optically coupled to the waveguide (10) for stabilising the wavelength of optical radiation (7) in the waveguide (10), one or more current conduction regions (4?, 4?) for guiding an applied electrical current to pump the laser waveguide (10) and at least one current constriction region (40) adjacent the one or more current conduction regions (4?, 4?). The DFB structure (6) extends in the current constriction region (40) and at least one of the current conduction regions (4?, 4?).