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Optoelectronics is the communication of optics and electronics which involves the study, design and manufacturing of hardware device which converts electrical energy into light and light into energy through semiconductors.
Made up of semiconductor materials.
Used in Military services, telecommunications,automatic access control systems and medical equipments.
Types of Optoelectronic devices
Light Emitting Diode(LED)
PN- Junction opto-semiconductor
Emits monochromatic light when operated in forward bais condition
Converts electrical energy to light energy
When sufficient voltage is applied to the leads of the LED, electrons move in one direction across the junction between the p and n regions.
The electrons recombine with the holes within the device.
Release energy in the form of photons.
This effect is called electroluminescence.
Advantages of LED
Consumes less power
Produces less heat
Last longer than incandescent lamps
Disadvantages of LED
Application of LED
Light sensor made up of semiconductor materials
When light falls on the junction, voltage or current is generated
PN- Junction diode, operated in reverse bais
When a photon(light) strikes a semiconductor, electron- hole pairs are generated through band-band optical absorption
Electric field is produced when the electron diffuse into the junction
This electric field across the depletion region is equal to the negative voltage across the unbaised diode. This is known as inner photoelectric effect
Optical energy(light) is converted to electrical energy(current/voltage) through optical receivers.
Refered to as O/E Converter.
Photodector is the fundamental element of optical receivers.
Advantages of Photo diode
Light weight and compact in size
Wide spectral response
Quick responce when exposed to light
Disadvantages of Photo diode
Low illumination levels due to reverse current
Applications of photodiode
Fire and smoke detectors
Photo sensors in camera
Dectectors for computed tomography
Blood gas monitors
Similar to bipolar junction transistor(BJT)
Only difference is that base current is produced and controlled by light except voltage source
Converts light energy to electrical signal
Have collector, base and emitter
Light sensitive collector base pn junction controls current flow between emitter and collector
Resistance decreases as intensity increases, creating more emitter-base current
The small base current controls the larger emitter-collector current
Advantages of Photo transistor
More sensitive than photodiodes of comparable size
Produce higher current than photodiodes
Fast response, compact enough to fit onto single integrated computer chip