The invention relates to an injected laser (200) comprising an optical gain medium (2) placed inside a triggered laser cavity (3), the optical gain medium (2) having a spectral gain bandwidth. According to the invention, the injected laser (200) includes an optical device (20) for modulating phase, which device is placed between the injection source (11) and the laser cavity (3), the optical device (20) for modulating phase being configured to periodically modulate as a function of time a phase of the monochromatic continuous-wave laser radiation (10) at a modulating frequency (fm) equal to a natural integer multiple of the free spectral range (FSR) of the laser cavity (3), so that the phase-modulated injection source generates polychromatic injection radiation (120).