Extending the width of caption for subfigure

Question

The caption of the subfigure follows the size of the figure/table. Is it possible to stretch the width so that it does not follow the size.

\documentclass[11pt,a4paper]{report}
\usepackage{
subfigure,
}

\begin{document}
\begin{figure}[htb]
\small
\centering
\subfigure[\label{fig:sub1}This is the first subfigure.]
{
\centering
\small
\begin{tabular}{l}
First sub figure
\end{tabular}
}
\\
\centering
\small
\subfigure[\label{fig:sub2} Second subfigure.]
{
\centering
\small
\begin{tabular}{l c*{2}{p{0.2cm}}}
$a$& 1 & 1  \\
$b$  & 2& 2 \\
\end{tabular} 
}
\\
\centering
\small
\subfigure[\label{fig:sub3} Third subfigure.]
{
\centering
\small
\begin{tabular}{l c*{2}{p{0.2cm}}}
$a$& 1 & 1  \\
$b$  & 2& 2 \\
\end{tabular}
}
\caption{\label{figure} This figure has 3 subfigures.} 
\end{figure}
\end{document}

This figure has 3 subfigures.

Answer 1

You can place the objects in a box having a prescribed width. In the code below, I've changed subfigure (which is an obsolete package) with subfig and \subfigure with \subfloat.

Watch also for spurious spaces that can sneak in the output, caused by unprotected end-of-lines. There's also no need to add \small\centering inside the \subfloat arguments.

\documentclass[11pt,a4paper]{report}
\usepackage{subfig}

\begin{document}
\begin{figure}[htb]
\small
\centering
\subfloat[\label{fig:sub1}This is the first subfigure.]
{%
\makebox[.4\textwidth]{\begin{tabular}{l}
First sub figure
\end{tabular}}%
}
\\
\subfloat[\label{fig:sub2}Second subfigure.]
{%
\makebox[.4\textwidth]{\begin{tabular}{l c*{2}{p{0.2cm}}}
$a$& 1 & 1  \\
$b$  & 2& 2 \\
\end{tabular}}%
}
\\
\subfloat[\label{fig:sub3}Third subfigure.]
{%
\makebox[.4\textwidth]{\begin{tabular}{l c*{2}{p{0.2cm}}}
$a$& 1 & 1  \\
$b$  & 2& 2 \\
\end{tabular}}%
}
\caption{\label{figure} This figure has 3 subfigures.} 
\end{figure}
\end{document}