The function of optoisolators is to allow the forward transmission of light through and isolate the backward transmission of light, so as to prevent the reflected light from affecting the stability of the system, similar to the function of diodes in electronic devices. Optoisolators are divided into two types in terms of polarization correlation: polarization correlation and polarization independent. The former is also known as free space type, because there is no fiber input and output at both ends; The latter is also called in-line, because there are fiber inputs and outputs at both ends.
