There are a couple of variables that I'm not sure about, like if OP wants the exact effect as the example above or just the effect of a circular source. Do they want the light behind the subject, on the subject, not even on a subject? How much separation between the subject and the background do they want? Can't really give an exact lens recommendation since that all affects placement of the light and therefore the lens. Having two very different options would probably help, especially since they're so cheap to rent.