\documentclass[crop,tikz,convert=pdf2svg]{standalone}
\usetikzlibrary{backgrounds}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\makeatletter
\begin{document}
\begin{tikzpicture}[scale=3,background rectangle/.style={fill=white}, show background rectangle]
	\begin{axis}[
		no markers,
		width=300,
		height=190,
		xmin = -4.1,	xmax = 4.1,
		ymin = -0.025,	ymax = 1.025,
		ytick = {0,0.25,0.5,0.75,1},
		yticklabels = {\(0\),\(\frac{1}{4}\),\(\frac{1}{2}\),\(\frac{3}{4}\),\(1\)},
		domain=-4.5:4.5,
		samples=512,
		xlabel=\(\frac{p - p_0}{w/2}\),
		ylabel={Intensity}
	]
	\addplot[color=red] {exp(-0.6931472*x^2)};
	\addplot[color=blue] {1/(1+x^2)};
	\addplot [color=black,dotted] coordinates {(0,-0.1) (0,1.1)};
	\addplot [color=black,dotted] coordinates {(1,-0.1) (1,1.1)};
	\addplot [color=black,dotted] coordinates {(-1,-0.1) (-1,1.1)};
	\addplot [color=black,dotted] coordinates {(-4.2,0.5) (4.2,0.5)};
	\legend{Gaussian, Lorentzian}
	\end{axis}
\end{tikzpicture}
\end{document}