Resonant Raman scattering by two LO phonons in InSb at the E1 transition

Abstract We have observed resonant Raman scattering of the 2LO phonon mode in InSb in the region of the E 1 transition. The resonant enhancement peak was found to be up-shifted by 19±4 meV from that of the one-phonon mode or by ∼ 60 meV from the E 1 peak in the optical spectrum of InSb. Our experimental results are explained qualitatively by the double resonance theory.