Drawing a "photodiode" symbol with TiKz

Question

A photodiode is typically depicted in the literature as a circle partially "hidden" by a rectangular bar. How does one go about drawing it with TiKz?

So far, I am using clip to "hide" part of a circle. Then, I superimpose a rectangle. The problem with this approach is that it simply masks the output (i.e., the resulting PDF still describes a full circle).

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\clip (0,0) rectangle (10mm,10mm);
\draw[inner color=orange!20, outer color=orange, draw, very thick]  (2.5mm,5mm) circle (4mm);
\draw[fill] (0,0) rectangle (1.2mm,10mm);
\end{tikzpicture}
\end{document}

Please show what you tried yourself. Can you for example draw a normal circle in TikZ? — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 11:46
This is not photodiode symbol For it see circuitikz, manual ,pp 239:-) — Zarko, Nov 22 '23 at 11:59
@Zarko Thanks! I am aware of how a photodiode is represented in an electrical circuit diagram. In laser optics, however, photodiodes are typically represented with the symbol I shared. — Mike D., Nov 22 '23 at 12:33
@samcarter_is_at_topanswers.xyz I will do as soon as I get close... so far I am trying to use circle and rectangle, but I am not able to "cut" the circle such that part of it is hidden (i.e., to avoid relying on just placing the rectangle on top of the circle). — Mike D., Nov 22 '23 at 12:35
@Zarko I have added another image to illustrate further what I mean :-) — Mike D., Nov 22 '23 at 12:37
@MikeD. Clipping away the top part is easy. Please show your circle and rectangle code — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 12:40
@samcarter_is_at_topanswers.xyz please take a look at the edited question. — Mike D., Nov 22 '23 at 13:05
@MikeD. Thanks for updating your question! What's the problem with "... it simply masks the output"? — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 13:07
If you don't want this, you could use an arc instead of a circle, but clipping is much easier. — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 13:08
@samcarter_is_at_topanswers.xyz I guess it's my OCD... Thanks for the tip on using arc! By the way, is it possible to shift the position of the center of the radial gradient inside the circle? — Mike D., Nov 22 '23 at 13:12
\draw[ball color=orange, shading angle=-45, draw, very thick] (2.5mm,5mm) circle (4mm); — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 13:19
... and see https://tex.stackexchange.com/a/268411/36296 and https://tex.stackexchange.com/a/58635/36296 on how to create your own shadings — samcarter_is_at_topanswers.xyz, Nov 22 '23 at 13:30
If you are going to worry about the structure underlying the visual appearance in the PDF, you have a lot of worrying to do and clipped circles will be the least of your worries. TikZ does this all over the place. Every time you use an arrow tip or double, for example. — cfr, Nov 22 '23 at 16:28

Jasper Habicht · Accepted Answer · 2023-11-22T18:22:53.703

Make use of a \pic:

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\tikzset{
    pics/photo diode/.style={
        code={
            \tikzset{photo diode/.cd, #1}
            \path[photo diode/bulb]
                ({-sqrt(3)*0.225},0) 
                arc[start angle=210, end angle=-30, radius=0.45]
                -- cycle;
            \path[photo diode/base] (-0.5,0) -- (0.5,0);
            \coordinate (-north) at (0,0.675);
            \coordinate (-south) at (0,0);
        }
    },
    photo diode/base/.style={
        draw,
        line width=4pt
    },
    photo diode/bulb/.style={
        draw,
        ball color=orange
    }
}
\begin{document}
\begin{tikzpicture}
\pic (P) at (0,0) {photo diode};
\pic[red] (Q) at (2,0) {photo diode={
    bulb/.append style={ball color=green}
}};
\draw (P-south) -- ++(0,-0.5) -| (Q-south);
\end{tikzpicture}
\end{document}

Edit to exactly position the anchor coordinates (thanks to Sebastiano):

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\tikzset{
    pics/photo diode/.style={
        code={
            \tikzset{photo diode/.cd, #1}
            \path[photo diode/bulb]
                ({-sqrt(3)0.225},0) 
                arc[start angle=210, end angle=-30, radius=0.45]
                coordinate[midway, yshift={0.5\pgflinewidth}] (-north);
            \path[photo diode/base] (-0.5,0) -- (0.5,0)
                coordinate[midway, yshift={-0.5*\pgflinewidth}] (-south);
        }
    },
    photo diode/base/.style={
        draw,
        line width=4pt
    },
    photo diode/bulb/.style={
        draw,
        ball color=orange
    }
}
\begin{document}
\begin{tikzpicture}
\pic (P) at (0,0) {photo diode};
\pic[red] (Q) at (2,0) {photo diode={
    bulb/.append style={ball color=green}
}};
\draw (P-south) -- ++(0,-0.5) -| (Q-south);
\end{tikzpicture}
\end{document}

@Sebastiano I also saw this the very moment I posted it =D . You are totally right, it looks strange. — Jasper Habicht, Nov 22 '23 at 18:18

Drawing a "photodiode" symbol with TiKz

1 Answers1