Optoelectronics (or optronics) is the study and application of electronic devices and systems that source, detect and control light, usually considered a sub-field of photonics. In this context, light often includes invisible forms of radiation such as gamma rays, X-rays, ultraviolet and infrared, in addition to visible light. Optoelectronic devices are electrical-to-optical or optical-to-electrical transducers, or instruments that use such devices in their operation.
Electro-optics is often erroneously used as a synonym, but is a wider branch of physics that concerns all interactions between light and electric fields, whether or not they form part of an electronic device.
Optoelectronics is based on the quantum mechanical effects of light on electronic materials, especially semiconductors, sometimes in the presence of electric fields.
Photoelectric or photovoltaic effect, used in:
photodiodes (including solar cells)
phototransistors
photomultipliers
optoisolators
integrated optical circuit (IOC) elements
Photoconductivity, used in:
photoresistors
photoconductive camera tubes
charge-coupled imaging devices
Stimulated emission, used in:
injection laser diodes
quantum cascade lasers
Lossev effect, or radiative recombination, used in:
light-emitting diodes or LED
OLEDs
Photoemissivity, used in
photoemissive camera tubeImportant applications of optoelectronics include:

Optocoupler
Optical fiber communications