I just had a quick look at a few scrap lasers which were hanging around
the
workshop, and they have six connections to the laser diode unit. Looking
at a few schematics, these are one each for the anodes and cathodes of the
laser diodes ( one red, and one infra red for DVD and CD respectively )
and one each for the feedback photo diode integrated with each laser
diode. The
snip

Just to be clear, I was referring to just the laser diode itself, not the
entire pickup.

Mark Z,