Types of Optoelectronics Devices with Applications

Optoelectronics is the communication between optics and electronics which includes the study, design and manufacture of a hardware device that converts electrical energy into light and light into energy through semiconductors. This device is made from solid crystalline materials which are lighter than metals and heavier than insulators. Optoelectronics device is basically an electronic device involving light. This device can be found in many optoelectronics applications like military services, telecommunications, automatic access control systems and medical equipments.

This academic field covers a wide range of devices including LEDs and elements, image pick up devices, information displays, optical communication systems, optical storages and remote sensing systems, etc. Examples of optoelectronic devices include telecommunication laser, blue laser, optical fiber, LED traffic lights, photo diodes and solar cells. Majority of the optoelectronic devices (direct conversion between electrons and photons) are LEDs, laser diodes, photo diodes and solar cells.

Types of Optoelectronics Devices

Optoelectronics are classified into different types such as

• Photodiode
• Solar Cells
• Light Emitting Diodes
• Optical Fiber
• Laser Diodes

Photo Diode

A photo diode is a semiconductor light sensor that generates a voltage or current when light falls on the junction. It consists of an active P-N junction, which is operated in reverse bias. When a photon with plenty of energy strikes the semiconductor, an electron or hole pair is created. The electrons diffuse to the junction to form an electric field.

This electric field across the depletion zone is equal to a negative voltage across the unbiased diode. This method is also known as the inner photoelectric effect. This device can be used in three modes: photovoltaic as a solar cell, forward biased as an LED and reverse biased as a photo detector. Photodiodes are used in many types of circuits and different applications such as cameras, medical instruments, safety equipments, industries, communication devices and industrial equipments.

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 a current and a voltage to produce electric power. Sunlight, which is composed of photons, radiates from the sun. When photons hit the silicon atoms of the solar cell, they transfer their energy to lose electrons; and then, these high-energy electron flow to an external circuit.

The solar cell is composed of two layers which are struck together. The first layer is loaded with electrons, so these electrons are ready to jump from the first layer to the second layer. The second layer has some electrons taken away, and therefore, it is ready to take more electrons. The advantages of solar cells are that, there is no fuel supply and cost problem. These are very dependable and require little maintenance.

The solar cells are applicable in rural electrification, telecommunication systems, ocean navigation aids, electric power generation system in space and remote monitoring and control systems.

Light-Emitting Diodes

Light-emitting diode is a P-N semiconductor diode in which the recombination of electrons and holes yields a photon. When the diode is electrically biased in the forward direction, it emits incoherent narrow spectrum light. 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. This effect is called as electroluminescence. It is the conversion of electrical energy into light. The color of the light is decided by the energy band gap of the material.

The usage of LED is advantageous as it consumes less power and produces less heat. LEDs last longer than incandescent lamps. LEDs could become the next generation of lighting and used anywhere like in indication lights, computer components, medical devices, watches, instrument panels, switches, fiber-optic communication, consumer electronics, household appliances, etc.

Optical Fiber

An optical fiber or optic fibre is a plastic and transparent fiber made of plastic or glass. It is somewhat thicker than a human hair. It can function as a light pipe or waveguide to transmit light between the two ends of the fiber. Optical fibers usually include three concentric layers: a core, a cladding and a jacket. The core, a light transmitting region of the fiber, is the central section of the fiber, which is made of silica. Cladding, the protective layer around the core, is made of silica.This creates an optical waveguide that limits the light in the core by total reflection at the interface of the core-cladding. Jacket, the non-optical layer around the cladding, typically consists of one or more layers of a polymer that protect the silica from the physical or environmental damage.

Along with the fiber-optic cable, jackets are available in different colors. These colors allow the recognition of the fiber-optic cable and the type of cable one is dealing with. For example, an orange-color cable clearly indicates a single-mode fiber, while a yellow one indicates a multimode fiber. In the single-mode fiber, one mode propagates and the light rays travel straight through the cable. In a multimode cable, the light rays travel through the cable following different modes.

These cables are used in telecommunications, sensors, fiber lasers, bio-medicals and in many other industries. The advantages of using optical-fiber cable include their higher bandwidth, less signal degradation, weightlessness and thinness than a copper wire, cost-effectiveness, flexibility, and hence they are used in medical and mechanical imaging systems.

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. The beam of a typical laser has 4×0.6mm extending at a distance of 15 meters. The most common lasers used are injection lasers or semiconductor lasers. The semiconductor laser changes from other lasers like solid, liquid and gas lasers

When a voltage is applied across the P-N junction, the population inversion of the electrons is produced, and then the laser beam is available from the semiconductor region. The ends of the P-N junction of the laser diode have polished surface, and hence, the emitted photons reflect back to create more electron pairs. Thus, the photons generated will be in phase with the previous photons.

Applications of Optoelectronics Devices

1. LEDs could become the next generation of lighting and used anywhere like in indication lights, computer components, medical devices, watches, instrument panels, switches, fiber-optic communication, consumer electronics, household appliances, traffic signals, automobile brake lights, 7 segment displays and inactive displays, and also used in different electronic and electrical engineering projects such as

• Propeller Display of Message by Virtual LEDs
• LED Based Automatic Emergency Light
• Mains Operated LED Light
• Display of Dialed Telephone Numbers on Seven Segment Display
• Solar Powered Led Street Light with Auto Intensity Control

2. The solar cells are applicable in rural electrification, telecommunication systems, ocean navigation aids, and electric power generation in space and remote monitoring and control systems and also used in different solar energy based projects such as

• Solar Energy Measurement System
• Arduino based Solar Street Light
• Solar Powered Auto Irrigation System
• Solar Power Charge Controller
• Sun Tracking Solar Panel

3. Photodiodes are used in many types of circuits and different applications such as cameras, medical instruments, safety equipments, industries, communication devices and industrial equipments.

4. Optical fibers are used in telecommunications, sensors, fiber lasers, bio-medicals and in many other industries.

5. The laser diodes are used in fiber optic communication, optical memories, military applications, CD players, surgical procedures, Local Area Networks, long distance communications, optical memories, fiber optic communications and in electrical projects such as RF Controlled Robotic Vehicle with Laser Beam Arrangement and so on.

Thus, this is all about the optoelectronic devices which include laser diodes, photo diodes, solar cells, LEDs, optical fibers.These optoelectronic devices are used in different electronic project kits as well as in telecommunications, military services and in medical applications. For more information regarding the same, please post your queries by commenting below.

Photo Credits:

• Laser Diodes by tutorvista
• Optoelectronic devices by channel4learning
• Photo Diode by depletedcranium
• Solar Cells by pveducation
• Light Emitting Diodes by photobiology
• Optical Fiber by electronicsweekly