The uniqueness of Poincar\'e type extremal K\"ahler metric

Let $D$ be a smooth divisor on a closed K\"ahler manifold $X$. Suppose that $Aut_0(D)=\{Id\}$. We prove that the Poincar\'e type extremal K\"ahler metric with a cusp singularity at $D$ is unique up to a holomorphic transformation on $X$ that preserves $D$. This generalizes Berman-Berndtson's work on the uniqueness of extremal K\"ahler metrics from closed manifolds to some complete and noncompact manifolds.