Well, recently I have been attracted to laser diodes. I am trying to make them work. Here is what I learnt-
1. LASER diodes are pretty current hungry,it will eat as much as it gets,since it's internal resistance is pretty low.
2. To make LASER diodes work properly, you need a CONSTANT current source.
3.Red Laser diodes need 3 - 4 volt to run.
4.You can make a Laser driver using LM-317 (it's called DDL)