A laser source for emitting a group of pulses, includes a primary laser source suitable for emitting at least one primary laser pulse; at least one interferometer suitable for forming, from the primary laser pulse, a plurality of secondary laser pulses, each interferometer comprising at least one delay line allowing two secondary laser pulses to be temporally separated, by a delay comprised between 50 ps and 10 ns; and a single-mode amplifying optical fiber intended to receive the secondary laser pulses, in order to form as output a group of spatially superposed pulses.