Components of Optoelectronics
The term optoelectronics is a specific discipline of electronics that focuses on light-emitting or light-detecting devices. These are the communication mediums between optics and electronics which includes the study, design and manufacture of a hardware device that converts electrical energy into light or light into energy through semiconductors. Light emitting devices use voltage and current to produce electromagnetic radiation i.e. light. The device is made from solid crystalline materials which are lighter than metals and heavier than insulators. Such light emitting devices are commonly used for purposes of illumination or as indicator lights.
In contrast, light detecting devices such as phototransistors, are designed to convert received electromagnetic energy into electric current or voltage. Light detecting devices can be used for light sensing and communications. Examples are darkness activated switches, remote controls etc. This device can be found in many opto-electronics applications like military services, telecommunications, automatic access control systems and medical equipments.
Types of Optoelectronics Devices
Opto-electronics are classified into different types such as:
- Photodiode – A photodiode is a semiconductor light sensor that generates a voltage or current when light falls on the junction.
- Solar cells – A solar cell or photo voltaic cell is an electronic device that directly converts sun’s energy into electricity. When sunlight falls on a solar cell, it produces both current and voltage to produce electrical power.
- Light Emitting Diodes – Light Emitting Diode is a P-N Semiconductor diode in which the recombination of electrons and holes yields a photon. When a voltage is applied to the leads of the LED, the electrons recombine with the holes within the device and release energy in the form of photons.
- Optical fiber – An optical fiber is a plastic and transparent fiber either made of plastic or glass. It is somewhat thicker than a human hair. It can function as a light pipe or wave guide to transmit light between the two ends of the fiber.
- Laser Diodes – LASER (Light Amplification by Stimulated Emission of Radiation) is a source of highly monochromatic, coherent and directional light. It operates under stimulated emission condition. The function of a laser diode is to convert electrical energy into light energy like infrared diodes or LEDs.
Opto-electronics Semiconductor materials:
Elemental semiconductors-Silicon, Germanium
Binary semiconductors-Aluminium, gallium, indium, phosphorus, arsenic, antimony
Ternary semiconductors-Aluminum, Gallium, Arsenic
Quaternary Semiconductors-Indium, Gallium, Phosphorous, Arsenic
Why semiconductor devices requiring emission or absorption of light?
Most LED chips are categorized as absorbing substrate devices, where the substrate material has a narrow band gap and absorbs all emission having energy greater than the band gap. Therefore, light traveling toward the sides or downward is absorbed, and such chips can only emit light through their top surfaces.
Why Opto-electronics sensor system used:
- The sensors used in an automotive environment must be reliable
- Produce exactingly accurate results
- Require little maintenance
- Help reduce overall system cost and extend the life of the system or sub system unit
- Integrated opto-electronics sensors are non-contact sensors, that is, they are able to perform their sensing or measurement functions without the need for physical contact with other parts of the system or sub-system
Advantages of Optoelectronics:
- Reducing the number of required components
- Improving the reliability of the system or sub-system
- Improving the styling, aesthetics and ergonomics of the overall vehicle through better utilization of the available space
- Improving the manufacturability of the vehicle by reducing the number of sensors that need to be positioned during production
- It is similar to human eye
- Output current easily obtainable
Disadvantages of Optoelectronics:
- They are not giving any direct feedback
- Contains Cadmium, a prohibited RoHS substance
- Small output current, so an amplifier required
- Poor temperature characteristics