Interferometric Shaping with a Single Laser

Varying pulse rise time by simply changing the pulse duration is not straightfoward because the laser pulses may differ in other respects. The principle of the interferometric method is to split each laser pulse into two pulses of unequal intensity, delay the main pulse and recombine them such that the low-intensity prepulse can interfere constructively or destructively with the leading edge of the main pulse, producing an increase or decrease in rise time. 

The advantage of the method is that it is external to the laser system and allows rapid and controlled adjustment of the rise time [45], 

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