I am doing an experiment in which I would like to block a laser beam, or allow it to be transmitted through on a nanosecond scale, based on the presence or absence of an electrical signal. When electricity is flowing to it, I would like it to block the beam, and when it is not flowing, it would allow the beam to pass through. I would like this to happen within a few nanoseconds of the signal being applied or removed. Can anyone think of a device or a way to construct a device that does this? I was thinking of smart glass, but this apparently works on far too slow a scale.