Efficient linear IC regulator for diodes?

So I was thinking that it would be nice to have a regulator like the LM317 and AMS1117 that are simple to use but that has a lower reference voltage and an equal or better voltage dropout.

After looking around the closest regulator I could find was the MCP1826T-ADJ.

It does come in a SOT-223 package that I use a lot for my builds.
However, it has one main differences. It has two more pins than the LM317, one is the shutdown pin and the other is a ground pin. The shutdown pin just needs to be connected to the input, but I'm not sure what needs to be done with the ground pin for it to work for a CC driver? If it even can work as a CC laser driver.

So my question for you electronics experts is, can this regulator be used as a laser driver and if so what needs to be done with the ground pin?

Possibly. It seems this ic wants to keep 0.41 volts on the adjust pin, so you could use it for a constant current application. The big difference between this and an lm317 is that you would want to put the sense resistor between laser diode and ground.

If you used 2 ohms for that it'd output a constant current of 200 mA or so, 400 mA for 1 ohm etc.

I am not sure it would operate stably like that though. The datasheet doesn't suggest this application, but that doesn't mean it is not possible. It does require an output cap to work though, so not suitable for conditions where the connection between driver and diode isn't solidly soldered in place.

`Efficient' and `linear regulator' don't usually go together. That part, in an SOT-223 package, has the potential to get quite hot. Heat sink it well.

It only works out well when supply voltage is above load voltage, but not by too much.

If you have, for example, a 7.4 volt nominal battery powering a 5.5 volt laser diode this works out pretty good (75% theoretical). This typially is also the range that gives switchmode supplies a hard time, i doubt many affordable buck converters can do this job more efficiently.