As the article points out, this is not a new technique. Increasing your resolving power by immersion of the target object in a liquid medium is actually used in ICs manufacturing.

This is because resolving power is directly proportional to numerical aperture, which is in turn proportional to the refractive index of the medium between the imaging device and the target object.

As a result, it works both ways: you can use it to increase resolution while either sending or receiving beams of light. For instance, the same technique is also used in light microscopy.

In the end, this is a clever and straightforward hack.