I have harvested several laser diodes out of old 16X to 22X DVD writers. I used a driver circuit based on LM 317 but I was not able to reach the lasing current of the diode. I do not have the specs sheet for any diode. I did experiment with various resistors to control the laser current but with no luck.
How can I experimentally determine threshold current of laser diode and the operating voltage of a unknown laser diode?
This driver is the one that I used.