PIE from previous acne can be treated by a wide range of lasers. This very recent review paper (Light-based devices in the treatment of cutaneous vascularlesions: An updated review) shows a compilation of more than 50 clinical papers of the options to treat vascular skin lesions. I shall summarize their findings below.
Long pulse visible light options like KTP (green) or CB/PDL (yellow) are extremely useful, with the yellow light options having most affinity to "redness" and more suitable for darker Asian skin types - still the GOLD STANDARD for treatment. Additionally, certain infrared wavelengths and even fractional technology can help with undulating scars together with the PIE.
IPL can be useful too, but is less suitable for darker Asian skin types because of range of wavelengths used in each filter encompasses wavelengths that are very readily absorbed by melanin. BBLs are an upgraded version of IPL, but are still less efficacious than the gold standard of vascular lasers. IPLs/BBL have a fair amount of literature supporting their use (5 clinical papers in the above mentioned article) and should be considered in the more budget conscious and fairer skin type patient.
Picosecond lasers are useless for this (nano and sub-nanosecond pulse durations have very minimal absorption in blood and redness). In the above systematic review which looks carefully at all the evidence available, there is zero mention of any pico or nano second lasers that can help with post inflammatory erythema. The lasers and light (IPL) options stated in the paper all have pulse durations in the millisecond duration for a good reason.
The Fotona Starwalker is an exception because it has a true Long-pulse and true Picosecond function within its platform.
Make sure you use sunblock well over the PIE spots. That can lessen the subsequent UV damage and PIH to those areas. Sunblock is also very important while doing your laser treatments!
