A system for generating signals for Raman vibrational analysis, particularly for a CARS microscope or spectroscope of an external specimen, the system including a laser source capable of emitting at least one fundamental optical pulse in a first band of fundamental frequencies including at least one first and one second fundamental frequencies; a second-harmonic generating system including at least one nonlinear optical crystal for converting the at least one fundamental optical pulse into a first and a second-harmonic optical pulse; and a Raman vibrational analysis apparatus capable of receiving the first and second second-harmonic pulses and direct them toward the specimen.