This is an odd thought, that I suspect I already know the answer to, but it lies well outside my expertise.
The solar gravitational focus is often touted as the ultimate natural telescope, waiting to be accessed if we can ever get a probe out that far. However, as powerfull as that gravitational lens is, it would be a passive scanning system.
My question is: is there any way it might be used as part of an active scanning system, in the same way that the Arecibo radio telescope can be used as a radar to probe the poles of mercury or passing aseroids?
After all, if it can be seriously proposed to build a laser that can reach across interstellar distances to propel a lightsail, why not use a similar scale transmitter of some wavelength to scan another star system?