Reference a picture

Question

I am writing a PhD thesis. Sometimes when I reference to a figure the following problem occurs. In PDF the word Fig.[number of figure] are written in two lines (Fig. and [] are separated). How to write the code that it will not be separated.

my code for figure:

\begin{figure}[h!]
\centering
\includegraphics[width=1.0\textwidth]{(4)13.png}
\caption{The dielectric permittivity bla bla bla.}
\label{(4)13}
\end {figure}

in text it is like

At the end of this chapter let us compare the numerical results for the phase mode frequency and dielectric response with experimental results. Fig. \ref{(4)13} shows the relaxation frequency ($\omega$) bla bla bla...

And in the PDF looks like:

Thank you very much for your help.

Best regards, Kristina