Control laser diode from digital pin
Your solution does not work, mainly because GPIOs are not intended to source current higher than a few mA. If you want the laser diode to emit a reasonable amount of power, you need to drive it with a transistor. A MOSFET-based low-side-switch would probably be the easiest solution. But note that you still need to limit the current, e.g. by using a series resistor.
Even better would be to use a constant current driver (you can use any led driver with appropriate rating).
If the power supply that came with the laser diode is a constant current source, it might be possible to switch its output directly (without resistor), but that depends on how it behaves when it is open-circuited.