Photonics

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Photonics is the physical science of light (photon) generation, detection, and manipulation through emission, transmission, modulation, signal processing, switching, amplification, and detection/sensing. Although it covers all the technical applications of light across the spectrum, most photonic applications are within visible and near-infrared light range. The term photonic was developed as a result of the first practical semiconductor light generator found in the early 1960s and the optical fiber developed in the 1970s.

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Histori

The word 'photonics' comes from the Greek word "phos" which means light (which has a genitive case of "photograph" and in compound word "photo-" used); appeared in the late 1960s to describe a field of research whose purpose was to use light to perform functions that traditionally fall in the typical domain of electronics, such as telecommunications, information processing, etc.

Photonics as a field began with the invention of lasers in 1960. Other developments followed: laser diodes in the 1970s, optical fibers for information transmission, and erbium-doped fiber amplifier. This discovery formed the basis for the telecommunications revolution at the end of the 20th century and provided the infrastructure for the Internet.

Although it was created earlier, photonic term came into common use in the 1980s as fiber optic data transmission was adopted by telecom network operators. At that time, the term was used extensively at Bell Laboratories. Its use was confirmed when the IEEE Laser and Electro-Optics Society established an archive journal called Photonics Technology Letters in the late 1980s.

During the period leading up to the dot-com crash around 2001, photonics as a field focused heavily on optical telecommunications. However, photonics cover a wide range of science and technology applications, including laser making, biological and chemical sensing, diagnostics and medical therapy, display technology, and optical computing. Further photonic growth is likely if the development of silicon photonics is currently successful.

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Relationships to other fields

Classic optics

Photonics is closely related to optics. Classical optics preceded the discovery that quantized light, when Albert Einstein famously explained the photoelectric effect in 1905. Optical devices include refractory lenses, reflective mirrors, and various optical components and instruments developed throughout the 15th to 19th centuries. The main teaching of classical optics, such as Principles Huygens, developed in the 17th century, Maxwell's equations and wave equations, developed in the 19th century, do not depend on the quantum nature of light.

Modern optics

Photonics is associated with quantum optics, optomechanics, electro-optics, optoelectronics and quantum electronics. However, each region has slightly different connotations by the scientific community and the government and in the market. Quantum optics often links fundamental research, whereas photonics are used to connote applied research and development.

The term photonic is more specifically connoted:

The nature of the light particles,
The potential to create signal processing device technology using photons,
Practical optical applications, and
Analogy for electronics.

The term optoelectronics connotes a device or circuit consisting of electrical and optical functions, that is, a thin-film semiconductor device. The term electro-optics goes into prior use and specifically includes nonlinear electrical-optical interactions that are applied, for example, as bulk crystal modulators such as Pockels cells, but also include advanced imaging sensors normally used for oversight by civil or government organizations.

Emerging fields

Photonics is also associated with the emerging science of quantum information and quantum optics, in cases where it uses photonic methods. Other emerging fields include optoacoustics or photoacoustic imaging in which laser energy delivered to biological tissues will be absorbed and converted into heat, leading to ultrasonic, optomechanics, which involves the study of the interaction between light and mechanical vibration of mesoscopic or macroscopic objects; opto-atomics, where devices integrate both photonic and atomic devices for applications such as precision precision, navigation, and metrology; polaritonics, which differs from photonics in which the fundamental information carrier is a polariton, which is a mixture of photons and phonons, and operates in the frequency range from 300 gigahertz to about 10 terahertz.

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Apps

Photonic applications are everywhere. Includes all areas of everyday life to the most advanced science, e.g. detection of light, telecommunication, information processing, photonic computing, lighting, metrology, spectroscopy, holography, medicine (surgery, vision correction, endoscopy, health monitoring), biophotonics, military technology, laser material processing, diagnostic art (involving InfraRed Reflectography, Xray, UltraViolet fluorescence, XRF), agriculture, and robotics.

Just as electronic applications have evolved dramatically since the first transistor was invented in 1948, a unique photonic application continues to emerge. Economically important applications for semiconductor photonic devices include optical data recording, fiber optic telecommunications, laser printing (based on xerography), displays, and laser pumping of high-power optics. Photonic potential applications are virtually unlimited and include chemical synthesis, medical diagnostics, on-chip data communications, laser defenses, and fusion energy, to name a few interesting examples.

Consumer equipment: barcode scanner, printer, CD/DVD/Blu-ray device, remote control device
Telecommunication: optical fiber communication, optical down converter to microwave
Drugs: poor vision correction, laser surgery, surgical endoscopy, tattoo removal
Manufacturing industry: laser usage for welding, drilling, cutting, and various surface modification methods
Construction: laser leveling, laser rangefinding, smart structure
Flights: Photonic gyroscopes have no mobile components
Military: IR sensor, command and control, navigation, search and rescue, laying and mine detection
Entertainment: laser show, light effects, holographic art
Information processing
Metrology: time and frequency measurement, range range
Photonic computing: the distribution of clocks and communication between computers, printed circuit boards, or in optoelectronic integrated circuits; in the future: quantum computing

Microphotonics and nanophotonics typically include photonic crystals and solid state devices.

Photonics for Professionals | von Gegerfelt Photonics

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Overview of photonic research

Photonic science includes the investigation of emissions, transmission, amplification, detection, and light modulation.

Light source

Light sources used in photonics are usually much more sophisticated than light bulbs. Photonics generally use semiconductor light sources such as light-emitting diodes (LEDs), superluminescent diodes, and lasers. Other light sources include single photon sources, fluorescent lamps, cathode ray tubes (CRTs), and plasma screens. Note that while CRTs, plasma screens, and organic light-emitting diode screens produce their own light, liquid crystal display (LCD) such as TFT screens require backlights from cold fluorescent neon lights or, more often today, LEDs.

Characteristics for research on semiconductor light sources are the frequent use of III-V semiconductors rather than classical semiconductors such as silicon and germanium. This is due to the special nature of the III-V semiconductor that enables the application of light-emitting devices. Examples for the material systems used are gallium arsenide (GaAs) and gallium aluminum arsenide (AlGaAs) or other compound semiconductors. They are also used in conjunction with silicon to produce hybrid silicon lasers.

Transmission media

Light can be transmitted through a transparent medium. Glass fibers or plastic optical fibers can be used to guide light along the desired path. In optical fiber optic communications it allows for a transmission distance of over 100 km without amplification depending on the bit rate and the modulation format used for transmission. The highly advanced research topic in photonics is the investigation and manufacture of special structures and "materials" with engineered optical properties. These include photonic crystals, photonic crystal fibers and metamaterials.

Amplifiers

Optical amplifiers are used to amplify optical signals. The optical amplifiers used in optical communications are erbium-doped fiber amplifiers, semiconductor optical amplifiers, Raman amplifiers and optical parametric amplifiers. A very advanced research topic on optical amplifiers is research on quantum dot semiconductor optical amplifiers.

Detect

Photodetectors detect light. Photodetectors range from very fast photodiodes to communication applications through high-speed medium coupled devices (CCDs) for digital cameras to very slow solar cells used to harvest energy from sunlight. There are also many other photodetectors based on thermal, chemical, quantum, photoelectric and other effects.

Modulation

The light source modulation is used to encode information on the light source. Modulation can be achieved by the light source directly. One of the simplest examples is to use a flashlight to send Morse code. Another method is to take light from a light source and modulate it in an external optical modulator.

The additional topic discussed by modulation research is the modulation format. On-off locking has become a commonly used modulation format in optical communications. In recent years, more advanced modulation formats such as phase-shift locking or even orthogonal frequency division multiplexing have been investigated to negate effects such as dispersions that degrade the quality of transmitted signals.

Photonic System

Photonics also includes research on photonic systems. This term is often used for optical communication systems. This research area focuses on the implementation of photonic systems such as high-speed photonic networks. It also includes research on optical regenerators, which improve the quality of optical signals.

Photonic integrated circuit

Photonic integrated circuits (PICs) are integrated semiconductor optical photon devices that are composed of at least two different functional blocks, (gain areas and lattice based mirrors in lasers...). This device is responsible for the success of commercial optical communications and the ability to increase available bandwidth without significant cost increases to end users, through improved performance and cost reductions they provide. The most widely used PICs are based on Indium phosphide material systems. Silicon photonics is an active research area.

Major applications for Integrated Photonics include -

Data Center: Today, Facebook, Amazon, Apple and Google themselves run a huge cloud computing data center. As companies and institutions store and process more information in the cloud, the demands on wired and wireless networks multiply. In 2013, the US National Resource Defense Council calculated that the data center consumed the equivalent of 34 large-scale coal-fired power plants (500-Megawatts), or enough energy to power New York City for two years. In the next seven years, the amount of data traffic is expected to double. Using integrated photonic technology, these centers will be able to handle large-scale terabit data speeds of traffic with nanosecond switching speed, while consuming only half the power, resulting in dramatic cost savings.

Analogue RF Signal Applications: Using GHz precision signal processing from photonic integrated circuits, radio frequency (RF) signals can be manipulated with high fidelity to add or drop multiple radio channels, spread over an ultra-broadband frequency range. Additionally, photonic integrated circuits can eliminate background noise from RF signals with unprecedented precision, which will increase the signal for noise performance and enable new benchmarks in low power performance. Taken together, this high-precision processing allows us to pack large amounts of information into remote radio communications.

Sensors: Photons can also be used to detect and distinguish optical properties of materials. They can identify chemical or biochemical gases from air pollution, organic products, and contaminants in the water. They can also be used to detect abnormalities in the blood, such as low glucose levels, and biometric measures such as pulse rate. Photonic integrated circuits are being designed as comprehensive and widespread sensors with glass/silicon, and embedded through high-volume production across various mobile devices.

The mobile platform sensor enables us to be more directly involved with practices that better protect the environment, monitor food supplies and keep us healthy.

LIDAR and other Streaked Array Imagery: Array PICs can take advantage of phase delays in reflected light from objects with three-dimensional shapes to reconstruct 3D images, and Light laser, Detection and Ranging (LIDAR) with laser light can offer a radar complement by providing precision imaging ( with 3D information) at close range. This new machine vision form has a direct application in the car without the driver to reduce collisions, and in biomedical imaging. Gradual arrays can also be used for free space communications and new display technologies. The current LIDAR version relies primarily on moving parts, making it large, slow, low-resolution, expensive, and prone to mechanical vibrations and premature failure. Integrated photonics can realize LIDAR in a footprint size the size of a postage stamp, scan without moving parts, and be produced in high volume at low cost.

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References

Source of the article : Wikipedia

Photonics

Selasa, 03 Juli 2018

Photonics

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Histori

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