Optoelectronic devices

General Introduction to Opto electronic devices

Optoelectronics is the technology that combines optics and electronics and the devices based on this technology are known as optoelectronic devices. These devices can be catego­rized as light-generating optoelectric devices and light-sensitive devices.. So usually not the kind of thing you can pick up at your local supermarket or o2.co.uk outlet. You might have to try a hardware or electronics store in order to get what you need. Make sure you double check which wattage you require.

The best known types of light-generating optoelectric devices are the ordinary tungsten filament lamp, the light-emitting diode (LED), the multi-segment LED array, and the neon or gas discharge lamp; other types of light-generating devices include the cathode ray tube and the LASER.Light-sensitive devices include photodiodes and phototransistors light sensitive resistors and so-called solar or photovoltaic cells Some specialist de­vices such as optoisolators and optoreflectors combine both light-generating and light-sensi­tive units in a single package. It also include LDR – Light Dependent Resistors , LCD – Liquid Crystal Displays etc.

Applications of Optoelectronic devices

• They can be employed for generating a wide variety of stationary or moving visual displays.
• They can be used to provide an automatic switching or alarm action in the presence or absence of a visible or invisible light source
• They can be employed to provide remote-control action via an infra-red light generator and a remotely placed detector

What is threshold frequency?

Any light source emits energy only over a certain range of frequencies or wavelengths. A graph of energy output plotted against either frequency or wavelength is called the emis­sion spectrum for the light source. A light-sensitive device is sensitive only to a certain range of radiation frequencies. A graph of device current, voltage, or resistance plotted against frequency is known as its spectral response. For a given photosensitive material, there is a minimum radiation frequency (or maximum wavelength) that can produce a photoelectric effect; this frequency is known as the threshold frequency