A circuit assembly controlling an optical system to generate optical pulses is provided. The optical system includes a seed light source optically coupled to an amplitude modulator. The circuit assembly includes a control circuit which generates a pulsed seed drive signal for driving the seed laser source, as well as logic signals defining successions of ON and OFF states and having a predetermined relative timing relationship. One or more of the logic signals is delayed by a corresponding programmable delay line to adjust the relative timing relationship between the logic signals. A logic gating module combines the logic signals according to one or more logical rule, thereby providing a modulator drive signal. Using this circuit assembly, the optical system outputs an optical pulse at each ON state of the modulator drive signal synchronized with the passage of one of the seed optical pulses through the amplitude modulator.