How to have the bold tip using xy package

From this old question Commutative Diagrams and TikZ, I have seen that there is an implies with the bold tip done with TikZ.

Is it possible to replicate with xy package to have the same tip or others bold tips?

I add a MWE:

documentclass[a4paper,12pt]{article}
usepackage[all,cmtip]{xy}

begin{document}
$xymatrix@1{
Aar@{=>}[r] &B
}$
end{document}