A laser module (1) comprises a Fabry-Perot cavity active element (2) with a facet (3) bearing an anti-reflection coating and an external cavity made by an optical fibre Bragg grating (5) with low reflectivity. This grating (5) presents a non-uniform profile of modulation of the refractive index, asymmetrical in the direction of the grating length, such as to give rise to a position of the equivalent mirror plane that is offset towards the end of the grating (5) that is closer to the active element (2).