The Measurement of Ultrashort Laser Pulses

Indeed, to see the action in any fast event, whether it’s a computer chip switching states, dynamite exploding, or a simple soap bubble popping, requires a strobe light with a shorter duration in order to freeze the action. But then to measure the strobe-light pulse requires a light sensor whose response time is even faster. And then to measure the light-sensor response time requires an even shorter pulse of light. Clearly, this process continues until we arrive at the shortest event ever created. And this event is the ultrashort light pulse. Ultrashort light pulses as short as a few femtoseconds have been generated, and it’s now routine to generate pulses less than 100 fs long. And we’d like to be able to measure their electric field vs. time or frequency.