Final
\documentclass[pstricks,border=12pt,12pt]{standalone}
\usepackage{amsmath}
\usepackage{pst-plot,pst-node}
\psset{algebraic,plotpoints=100,labelsep=3pt}
\def\f[#1,#2]{2*2^(-2.5*(#1-#2)^2)}
\begin{document}
\begin{pspicture}[showgrid=false](-3,0)(3.5,3)
\psaxes[axesstyle=frame,tickstyle=bottom,ticks=x,ticksize=0 4pt,xsubticks=5,xsubticksize=.5,labels=none](0,0)(-3,0)(3,3)
\uput[d](-1,0){$\omega_{\text{nl}}$}
\uput[d](1.5,0){$\omega_{\text{lin}}$}
\uput[d](0,0){\tiny Frequency}
\psline{<-}(0,2)(1,2)
\psset{linecolor=gray}
\psline[linestyle=dashed](0,0)(0,3)
\psplot[linecolor=red,linestyle=dashed]{-3}{1}{\f[x,-1]}
\psplot[linecolor=red]{-.5}{3}{\f[x,1.5]}
\pcline{<->}(*-1.5 {\f[x,-1]})(*-.5 {\f[x,-1]})\nbput{$r_{\text{nl}}$}
\pcline{<->}(*1 {\f[x,1.5]})(*2 {\f[x,1.5]})\nbput{$r_{\text{lin}}$}
\end{pspicture}
\end{document}

dia
picture: see e.g. drawing-on-an-image