In this MWE, how could you add a circumflex inside pdfstring argument of the \texorpdfstring command so it can be displayed in the pdf bookmarks?
MWE:
\documentclass{article}
\usepackage{amsfonts}
\usepackage{hyperref}
\begin{document}
\section{\texorpdfstring{Section $\mathbb{R}^k$}{Section R^k}}
Blah blah
\section{\texorpdfstring{Section $\mathbb{R}^k$ bis}{Section R\^k}}
Blah blah
\section{\texorpdfstring{Section $\mathbb{R}^k$ bis bis}{Section R\^ k}}
Blah blah
\end{document}
And this is what I am currently obtaining in the bookmarks:

What I would like to display in the bookmark is "Section R^k", with the circumflex (if this is possible...).
textcompis a useful package anyway (I just load it by default the same way I enable the T1 encoding and UTF8 input - it isn't worth thinking about whether I need it or not). – cfr Oct 11 '14 at 02:21