  We introduce an atomic gravimetric sequence using Raman-type composite light
pulses that excites a superposition of two momentum states with the same
internal level. The scheme allows the suppression of common noise, making it
less sensitive to external fluctuations of electromagnetic fields. The Raman
beams are generated with a fiber modulator and are capable of momentum transfer
in opposite directions. We obtain analytical expressions for the interference
fringes in terms of three perturbative parameters that characterize the
imperfections due to undesired frequencies introduced by the modulation
process. We find special values of the Rabi frequency that improve the fringes
visibility.
