Will Hair Grow Back Shorter After Laser Hair Removal?

Laser hair removal permanently effects the hair follicles treated. The laser heats the pigment in the follicle and destroys it, it will never grow hair again. Thicker darker hairs are more sensitive to the laser and will be more easily treated.
Lighter colored, more downy hairs are more difficult to treat. Hair length should not be effected, just the density of the hair. Each treatment session will remove more hair, and you can stop when you have reached the amount of hair with which you are comfortable.

You should expect 75%-90% decrease in the growth of your treated hair, if you're a good candidate for Permanent Hair Removal. Although the remaining hairs will be lighter, thinner, and slower growing, these will grow to full length.
I hope this is helpful for you.

Hair follicles destroyed by the laser will not regrow.. Hair follicles injured by the laser will be finer, lighter and will take longer to grow.

Typically, laser hair removal works by targeting the hair follicle and destroying it so hair no longer grows. This is achieved by multiple treatments over many months (6-8 on average depending on the density and thickness of the hair). With each treatment, less hair should grow back and whatever that does may be thinner and finer, but the length usually doesn't change. The thicker, coarser hairs respond better to laser hair removal while the finer hairs may be more resistant. So if you don't want the hair to be completely removed you can stop treatments at the point at which the density of hair in the area is less because less hair is growing back.
Hope this helps!