Optoelectronic Devices

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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

1-They can be employed for generating a
wide variety of stationary or moving
visual displays.

2-They can be used to provide an
automatic switching or alarm action in
the presence or absence of a visible or
invisible light source

3-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

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