It's a logo for an LED diode. It is made up of a rectangle with two lines going down vertically to form a base with a half circle on top of the rectangle where the light would be.
This page shows the different variations of the LED Diode from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free.
Idea of LED Diode Icon by Viktor
We've received the idea on June 18, 2013 and created the icons on June 30, 2013
I will be great if you add these icons to you icon set: Integrated Circuit (IC - Analog and Digital, TTL and CMOS), LED diodes, Transistor (PNP, NPN, FET), Transistor packaging (DIL, DIP, TO), Resistor, Capacitor, Display etc...