If all you want to do is 'paint' the target with the laser designator, and know whether or not the laser is on target, the solar cell will work. I can't recall exactly what voltage I got out of it when we hit it with a laser pointer, but I'm certain that it would be enough to either a) bring a PIC digital input high, or b) supply enough to the base of a 2n2222 or similar transistor to make the input high. The size of the cell is around a half to three quarters of an inch by about an inch or inch and a quarter. If you placed it so that it was shaded by a short piece of tubing or something that would also give the person operating the laser something to aim at.
In this case, the only data would be on target, or not on target, so you wouldn't need to chop or modulate the laser beam, just turn it on to paint the target, and off when your done.

Jerry