A post-assembly wavelength-tuning method for an optical filter provided along an optical fiber mounted under tension in a packaging assembly is provided. The packaging assembly includes at least one packaging component mechanically coupled to the optical fiber and optically accessible from outside of the packaging assembly. The method includes a step of measuring a post-assembly spectral response of the optical filter and determining therefrom a spectral deviation with respect to a target spectral response. The method also includes a step of forming one or more laser-welded zones on the packaging component so as to cause a permanent deformation thereof. The permanent deformation induces a modification in length of the optical fiber, thereby changing the post-assembly spectral response of the optical filter to compensate for the measured spectral deviation.