  We report systematic first-principles investigation of light-induced
mechanical deformations in monodomain (PbTiO$_{3}$)$_{n}$/(SrTiO$_{3}$)$_{n}$
superlattices ($n=1-5$). We reveal that photostriction in these
heterostructures quantitatively and qualitatively depends on the chemical
period $n$. Specifically, we show that by changing the chemical period, we can
induce $\textit {positive}$ or $\textit {negative}$ photostriction. We also
present a simple analytical model to account for the calculated deformations.
Our findings indicate that superlattices architectures may be key to design
novel optomechanical applications.
