Is it possible to have a laser treatment after I use self tan lotion?

I suggest that you remove the self tanner as much as possible through exfoliation before you have your laser treatment.  For the best results you should discontinue the self tanner before you have a laser treatment.  For the best results please consult a board certified dermatologist who is a specialist in lasers and cosmetic procedures.

Certain lasers such as Alexandrite and Yag lasers,
typically used for brown spots, tattoos, and hair removal, work by detecting
pigment. When patients are tanned, whether through UV rays or self-tanner, it
can confuse the laser and cause increased heat absorption in the upper layers
of the skin. This can increase the likelihood of unwanted side effects such as
burns, blisters, and hyper/hypopigmentation.

While the Fraxel laser, a fractionated
resurfacing laser, works differently from the aforementioned technologies, I
would personally suggest you postpone treatment. The risk of having any real
effect on your end result is minimal, however waiting for the majority of the
self-tanner to fade can ensure less complication. Letting your skin return to its natural state will also allow you to better gauge your results,
and see the true effect of the Fraxel laser. Be sure to consult with a board
certified Dermatologist for pre and post treatment protocol; best of luck!