Effect of atomic recoil on the absorption spectrum of driven V-type atoms

A numerical method is developed for a V system driven by two counterpropagating laser fields in a momentum regime where a full quantum-mechanical treatment of the atomic variables is necessary. This method is based on a transformation by which integral equations, reduced from steady-state optical-Bloch-type equations involving the atomic center-of-mass momentum, can be transformed into inhomogeneous tridiagonal vector recurrence equations. The effect of the atomic recoil on the momentum distribution in the absence of the probe field, and, in particular, the absorption spectrum in a copropagating spectrum configuration is analyzed and discussed. Special attention is given to the Rayleigh resonance of subnatural linewidth.