We have investigated the lattice vibrational properties of a two-component strained layer semiconductor superlattice (GaAs)_n1 (GaSb)_n2 using a one-dimensional linear chain model and transfer matrix method [1]. Effect of strain, arising due to the lattice mismatch (∼ 7%) has been considered explicitly in the equation of motion. We show for the first time that the optical vibrational frequency increases (in the case of (GaAs)₄ (GaSb)_n) or decreases (in the case of (GaAs)_n(GaSb)₄) with increase of layer thicknessn, in either type of superlattices. Raman scattering measurements on some other similar systems support our findings.