I'm doing a very strange photoacoustic experiment that requires that I block a laser beam (or any light source for that matter) to a target such that the light's fall time (90% to 10% of incident intensity) occurs in 33 picoseconds or less.

What are my options? Is there any way I can do this for less than $1000? The convenient part is that I do not need to necessarily have a pulsed light source/laser source, I only need to turn off the light source/block it within the 33 picosecond window for it to work (I think).

Also, I've considered making an interferometer setup to destructively interfere the light to "turn it off" but it seems to me that it would still not be fast enough to turn it off in 33 picoseconds unless I had a light source that had a rise/fall time of 33 picoseconds as well.