A device and a method for aligning a laser unit to a waveguide unit. The method may include (a) placing the laser unit in a tested position in which the laser unit faces the waveguide unit;(b) supplying light, via a coupler of the waveguide unit, to an alignment waveguide of the waveguide unit; (c) receiving light emitted from the alignment waveguide; wherein the light was emitted as result of the supplying of the light; (d) determining whether the light emitted from the alignment comprises a spectral signature associated with an alignment unit of the laser unit; and (e) estimating whether the laser unit is aligned to the waveguide unit based on the determining of step (d).