Efficient temporal shaping of ultrashort pulses with birefringent crystals.

We report on a simple and robust technique to temporally shape ultrashort pulses. A number of birefringent crystals with appropriate crystal length and orientation form a crystal set. When a short pulse propagates through the crystal set, the pulse is divided into numerous pulses, producing a desired temporal shape. Flexibility in the final pulse shape is achieved through varying initial pulse duration, divided-pulse number, the polarization-mode delay, and energy distribution of the divided pulses. The energy efficiency of the technique is near 100% for a pulse train of alternating polarizations, and 50% for a linearly polarized pulse train.