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We have studied the wavevector dispersion of the L+ coupled mode in n-type In 0.53 Ga 0.47 As by means of Raman scattering using several excitation wavelengths in the range between 457.9 and 720 nm. The optical properties of In 0.53 Ga 0.47 As in the range of excitation energies used are strongly affected by the presence of the E 1 and E 1+ Δ 1 critical points, and set an upper limit to the wavevector that can be probed by decreasing the excitation wavelength in Raman scattering experiments. The Raman scattering results are analysed using a Lindhard–Mermin model, and it is found that optical absorption strongly affects the coupled-mode Raman peaks excited with the more energetic lines.