Hi,
Darkening of pigmentation after laser on the face can sometimes occur, especially in Asians or darker skin individuals. While this can happen with all types of lasers, certain lasers with a shorter pulse width, such as the nanosecond Q switched lasers as well as picosecond lasers will carry a higher risk.
In Asians, a longer pulse width laser such as that used in the Alextrivantage laser or Cutera Excel V laser will carry a lower risk of post laser pigmentation.
If you do already have darkening, medical grade lightening creams can help fade it faster. Do see your doctor or Dermatologist for further advice.