Could I use this as a simple infrared sensor then? Say if I covered up the emitter then looked for any source of infrared (I know that this would no longer work as a distance sensor), but would it recognize that there is infrared light? I guess what I'm asking is if it is possible to use a sharp distance sensor as a infrared light receiver, and if so,
You could, but that's not saying that it's sensible, as it is very expensive compared to a regular photo transistor and it's extremely slow compared.
Why would you wanna do that at all?
is there any distances that would make it work/not work?
Yes... Experiment to find it
Also, what range of wavelengths do the Sharp sensors detect?
I've never seen that info in any datasheet and I probably never will, as it's extremely unrelated to conventional use. The emitter and the receiver array are matched of course.
If you really wanna know, get access to an IR spectrometer and test it with a range of IR LEDs from say 750nm to ~1000nm and then interpolate for the wavelengths you don't have LEDs for.