\begin{tikzpicture}[>=stealth', auto, node distance=0.9cm, scale=2,
    dot/.style={fill, circle, inner sep=0, minimum size=0.1cm}]

    \draw[->] (-2,0) -- (-1,0) node[dot]{} node[anchor=north]{$-1$} -- (0,0) node[anchor=north west]{$0$} -- (0.5,0) node[anchor=north west]{$0.5$}-- (1,0) node[anchor=north west]{$1$} -- (2,0) node[anchor=west]{$\Re(s)$};

    \draw[->] (0,-1.2) -- (0,1.2) node[anchor=south]{$\Im(s)$};
    \begin{scope}[yscale=0.1]
        \draw[] (1,-1) -- (1,1);
    \end{scope}
    \draw[dotted] (0.5,-1) -- (0.5,1);

    \begin{scope}[]
        \fill[opacity=0.2, red] (-1.8,1) rectangle (0, -1);
        \fill[opacity=0.2, blue] (0,1) rectangle (1, -1);
        \fill[opacity=0.2, green] (1,1) rectangle (1.8, -1);
    \end{scope}

\end{tikzpicture}