What is a waveguide photodiode?

Photodiode is a semiconductor device that converts optical signals into electrical signals. Its core part is also the PN junction. Compared with ordinary diodes, the structural difference is that in order to receive incident light, the PN junction area should be as large as possible and the electrode area should be as small as possible, and the junction depth of PN junction is very shallow, generally less than 1 micron.

Photodiode works under the action of reverse voltage. When there is no light, the reverse current is very small (generally less than 0. 1 microampere), which is called dark current. When there is light, photons carrying energy enter the PN junction, transferring energy to bound electrons on the valence bond of * * *, so that some electrons are separated from the valence bond of * * *, resulting in electron-hole pairs, which are called photogenerated carriers.

They participate in the drift motion under the action of reverse voltage, which makes the reverse current obviously larger, and the greater the light intensity, the greater the reverse current. This property is called photoconductivity. The current generated by photodiode under the illumination of light with general illumination is called photocurrent. If a load is connected to an external circuit, an electrical signal is obtained on the load, which changes with the change of light.