You can find small laser diodes like LC-LMD-650-01-03-A that are 8.5, 6.5 or even less mm in diameter and only drain about 20mW.
In one of my old Sony-Ericsson phones, I replaced the LED with such a diode and I could activate the laser beam instead of the phone LED. I would of wanted to integrate a green one, but they were too large to fit in the phone case.