There are optical drive emulators available for various consoles that emulate at the hardware layer, but none that I know of for generic SATA/ATAPI/IDE interfaces.
There *ARE* optical drive emulators that present as USB CD/DVD drives though. Here is an example from Startech, there's also a Zalman-branded one.
https://www.startech.com/support/S2510BU3ISO
Obviously this does no good if you're trying to stick it in your CD32 or whatever.