Short light pulses can be generated by interferometer systems commonly used as all optical switches in telecommunication applications. The method of pulse generation does not involve lasing and transforms an optical square-wave input with slow rise times into a short-pulse train. A mathematical model for the system is developed. Conditions for correct operation of the system are derived from the model. Simulations illustrate the system operation. Furthermore, initial experiments are performed using a combination of fiber and free space optics. The experiments demonstrate the controllable pulse width and obtain pulsewidths of down to approximately 1 ps.