我需要将图形的轴与圆心对齐，尽管我使用了与水平线宽度相同的值，但它们与半径不匹配。所有这些怎么可能
\documentclass[border=10pt]{standalone}
\usepackage{xcolor}
\definecolor{lava}{rgb}{0.81, 0.06, 0.13}
\definecolor{myblue}{rgb}{0.0, 0.30, 0.60}
\usepackage {ifthen}
\usepackage {tikz}
\usetikzlibrary{calc}
\definecolor{metallicBlue}{RGB}{44,88,128}
\tikzstyle arrowstyle=[scale=1]
\usetikzlibrary{arrows,shapes,positioning}
\tikzstyle directed=[postaction={decorate,decoration={markings,mark=at position .65 with {\arrow[arrowstyle]{stealth}}}}]
\tikzstyle reverse directed=[postaction={decorate,decoration={markings,mark=at position .65 with {\arrowreversed[arrowstyle]{stealth};}}}]
\usetikzlibrary{angles, arrows.meta,quotes}
\usepackage{pgfplots,tikz}
\pgfplotsset{myplot/.style={ samples=50, smooth, no marks,hide axis} }
\usetikzlibrary{angles, arrows.meta,quotes}
\usepackage{pgfplots,tikz}
\usetikzlibrary{decorations.markings}
\usetikzlibrary{decorations.text,calc,arrows.meta}
\begin{document}
\begin{tikzpicture}
\coordinate (O) at (0,0);
\draw (O) circle (2.5);
\draw (O) circle (1.5);
\draw (O) circle (0.5);
\draw[decoration={text along path,reverse path,text align={align=center},text={core}},decorate] (0.6,0) arc (0:180:0.6);
\draw[decoration={text along path,reverse path,text align={align=center},text={Cladding}},decorate] (1.6,0) arc (0:180:1.6);
\draw[decoration={text along path,reverse path,text align={align=center},text={Jacket}},decorate] (2.6,0) arc (0:180:2.6);
\begin{scope}[xshift=0,yshift=-8cm]
\begin{axis}[
x axis line style={-stealth},
y axis line style={-stealth},
ymax = 1.5,xmax=2.5,
axis lines*=center,
ytick={0.3,0.8,1},
yticklabels={$n_0$,$n_2$,$n_1$},
xtick={0.3,1},
xticklabels={a,b},
xlabel={Radial distance},
ylabel={Index},
xlabel near ticks,
ylabel near ticks]
\addplot[thick,mark=none,const plot,myblue]
coordinates
{(0,1) (0.5,0.8) (1.5,0.3)(2.5,0.3)};
\end{axis}
\end{scope}
\end{tikzpicture}
\end{document}