Wavelength tunable filtering in optical telecommunications can be done by taking advantages of the acousto-optic interaction in anisotropic medium and especially with a quasi-collinear interaction in paratellurite crystal. The objective of the paper is to point out the limit of the functioning of such a component, in the case of a multi-wavelength filter application. The dynamic behavior (i.e. the temporal evolution) of the optical diffraction efficiency according to the operating conditions is presented and discussed. Experimental and simulation results, in telecommunication wavelength range, are shown.