IR LD's from DVD burners usually have 2 things that can help identify
prior to a power up test.. 1- the IR LD may not have a 'window' where the
red will (if closed can). And 2- the IR may also have a number etched
into the side of the can.
Posting pics may also be of great help... Not much to go on in this thread
Also, if you power a bare diode with no collimating lens and face it toward
the floor or wall, it would not be much of an eye hazard, just point it
away from yourself and there is not much to worry about.
You can also feed the LD a low current of 60-70mA, it will be obvious
to which LD you have in hand. IR you wont see anything at a low current,
and the red will very easy to spot..
Also, the GCA-4166B appears to be a 16x burner, so im assuming the LD is
a closed can type and current should not exceed 200-250mA.