Last night I tried pulsing the laser diode in a cheap 5 mW green laser pointer. I was able to get gain switching behavior from 10s of KHz up to maybe a few hundred KHz with 100KHz giving about the best gain switching behavior. I had 0 bias current and a nominal 50/50 duty with a max current of maybe 200mA. I was able to get 100nS pulses that occurred around the end of the diode pulse with a fair amount of jitter. I would guesstimate that the peak power was in the neighborhood of 500mW. I do have the equipment to do better measurements but I was mainly just curious to try it.
Now with the cavity so short in these things I would guess if it were nailed with a higher power shorter pulse, a pulse maybe on the order of a nS could be had.

Anyone have experience with gain switching?