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Optical Networking
Optical networking is a means of communication that uses signals encoded in light to transmit information in various types of telecommunications networks. These include limited range Local area network, local-area networks (LAN) or wide area networks (WANs), which cross metropolitan and regional areas as well as long-distance national, international and transoceanic networks. It is a form of optical communication that relies on Optical amplifier, optical amplifiers, lasers or Light-emitting diode, LEDs and wavelength-division multiplexing (WDM) to transmit large quantities of data, generally across fiber-optic cables. Because it is capable of achieving extremely high Bandwidth (computing), bandwidth, it is an enabling technology for the Internet and communication networks, telecommunication networks that transmit the vast majority of all human and machine-to-machine information. Types Fiber-optic networks The most common Fiber-optic network, fiber-optic networks are communication n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications Network
A telecommunications network is a group of Node (networking), nodes interconnected by telecommunications links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, message switching, or packet switching, to pass messages and signals. Multiple nodes may cooperate to pass the message from an originating node to the destination node, via multiple network hops. For this routing function, each node in the network is assigned a network address for identification and locating it on the network. The collection of addresses in the network is called the address space of the network. Examples of telecommunications networks include computer networks, the Internet, the public switched telephone network (PSTN), the global Telex network, the aeronautical ACARS network, and the wireless radio networks of cell phone telecommunication providers. Network structure this is the structure of network genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free-space Optical Communication
Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking over long distances. "Free space" means air, outer space, vacuum, or something similar. This contrasts with using solids such as optical fiber cable. The technology is useful where the physical connections are impractical due to high costs or other considerations. History Optical communications, in various forms, have been used for thousands of years. The ancient Greeks used a coded alphabetic system of signalling with torches developed by Cleoxenus, Democleitus and Polybius. In the modern era, semaphores and wireless solar telegraphs called heliographs were developed, using coded signals to communicate with their recipients. In 1880, Alexander Graham Bell and his assistant Charles Sumner Tainter created the photophone, at Bell's newly established Volta Laboratory in Washington, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wavelength-division Multiplexing
In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This technique enables bidirectional communications over a single strand of fiber (also called wavelength-division duplexing) as well as multiplication of capacity. The term WDM is commonly applied to an optical carrier, which is typically described by its wavelength, whereas frequency-division multiplexing typically applies to a radio carrier, more often described by frequency. This is purely conventional because wavelength and frequency communicate the same information. Specifically, frequency (in Hertz, which is cycles per second) multiplied by wavelength (the physical length of one cycle) equals velocity of the carrier wave. In a vacuum, this is the speed of light (usually denoted by the lowercase letter, c). In glass fiber, velocity is substan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Circulator
An optical circulator is a three- or four-port optical device designed such that light entering any port exits from the next. This means that if light enters port 1 it is emitted from port 2, but if some of the emitted light is reflected back to the circulator, it does not come out of port 1 but instead exits from port 3. This is analogous to the operation of an electronic circulator. Fiber-optic circulators are used to separate optical signals that travel in opposite directions in an optical fiber, for example to achieve bi-directional transmission over a single fiber. Because of their high isolation of the input and reflected optical powers and their low insertion loss, optical circulators are widely used in advanced fiber-optic communications and fiber-optic sensor applications. Optical circulators are ''non-reciprocal'' optics, which means that changes in the properties of light passing through the device are not reversed when the light passes through in the opposite dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Splitter
A beam splitter or beamsplitter is an optical device that splits a beam of light into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespread application in fibre optic telecommunications. Designs In its most common form, a cube, a beam splitter is made from two triangular glass prisms which are glued together at their base using polyester, epoxy, or urethane-based adhesives. (Before these synthetic resins, natural ones were used, e.g. Canada balsam.) The thickness of the resin layer is adjusted such that (for a certain wavelength) half of the light incident through one "port" (i.e., face of the cube) is reflected and the other half is transmitted due to FTIR (frustrated total internal reflection). Polarizing beam splitters, such as the Wollaston prism, use birefringent materials to split light into two beams of orthogonal polarization states. Another design is the use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Switch
An optical transistor, also known as an optical switch or a light valve, is a device that switches or amplifies optical signals. Light occurring on an optical transistor's input changes the intensity of light emitted from the transistor's output while output power is supplied by an additional optical source. Since the input signal intensity may be weaker than that of the source, an optical transistor amplifies the optical signal. The device is the optical analog of the electronic transistor that forms the basis of modern electronic devices. Optical transistors provide a means to control light using only light and has applications in optical computing and fiber-optic communication networks. Such technology has the potential to exceed the speed of electronics, while conserving more power. The fastest demonstrated all-optical switching signal is 900 attoseconds (attosecond =10^-18 second), which paves the way to develop ultrafast optical transistors. Since photons inherently do n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reconfigurable Optical Add-drop Multiplexer
In optical communication, a reconfigurable optical add-drop multiplexer (ROADM) is a form of optical add-drop multiplexer that adds the ability to remotely switch traffic from a wavelength-division multiplexing (WDM) system at the wavelength layer. This is achieved through the use of a wavelength selective switching module. This allows individual or multiple wavelengths carrying data channels to be added and/or dropped from a transport fiber without the need to convert the signals on all of the WDM channels to electronic signals and back again to optical signals. The main advantages of the ROADM are: * The planning of entire bandwidth assignment need not be carried out during initial deployment of a system. The configuration can be done as and when required without affecting traffic already passing the ROADM. * ROADM allows for remote configuration and reconfiguration. * In ROADM, as it is not clear beforehand where a signal can be potentially routed, there is a necessity of power ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Add-drop Multiplexer
An optical add-drop multiplexer (OADM) is a device used in wavelength-division multiplexing (WDM) systems for multiplexing and routing different channels of light into or out of a single-mode fiber (SMF). This is a type of optical node, which is generally used for the formation and the construction of Optical networking, optical telecommunications networks. "Add" and "drop" here refer to the capability of the device to add one or more new wavelength channels to an existing multi-wavelength WDM signal, and/or to drop (remove) one or more channels, passing those signals to another network path. An OADM may be considered to be a specific type of optical cross-connect. A traditional OADM consists of three stages: an optical demultiplexer, an optical multiplexer, and between them a method of reconfiguring the paths between the demultiplexer, the multiplexer and a set of ports for adding and dropping signals. The demultiplexer separates wavelengths in an input fiber onto ports. The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexer
In electronics, a multiplexer (or mux; spelled sometimes as multiplexor), also known as a data selector, is a device that selects between several Analog signal, analog or Digital signal (electronics), digital input signals and forwards the selected input to a single output line. The selection is directed by a separate set of digital inputs known as select lines. A multiplexer of 2^n inputs has n select lines, which are used to select which input line to send to the output. A multiplexer makes it possible for several input signals to share one device or resource, for example, one analog-to-digital converter or one communications transmission medium, instead of having one device per input signal. Multiplexers can also be used to implement Boolean algebra, Boolean functions of multiple variables. Conversely, a demultiplexer (or demux) is a device that takes a single input signal and selectively forwards it to one of several output lines. A multiplexer is often used with a complem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facebook Aquila
The Facebook Aquila was an experimental solar-powered drone developed by Facebook for use as an atmospheric satellite, intended to act as relay stations for providing internet access to remote areas. The Aquila first flew on 28 June 2016 with a second aircraft successfully flying in 2017. Internal development of the Aquila aircraft was stopped in June 2018. Development Aquila was developed by Facebook's Connectivity Lab. The prototype airframe design and construction was led by Ascenta, a Somerset, England-based company acquired by Facebook in 2014. Several scale models of the Aquila were built and flown to prove the concept prior to the full-scale prototype being built. Following construction at Ascenta's factory in Bridgwater, England, the Aquila prototype was disassembled and shipped to Arizona, where it was first flown on 28 June 2016. The 96-minute flight was considered successful. However, during landing, the aircraft touched down short of the intended landing zone and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Project Loon
Loon LLC was an Alphabet Inc. subsidiary working on providing Internet access to rural and remote areas. The company used high-altitude balloons in the stratosphere at an altitude of to to create an aerial wireless network with up to 1 Mbit/s speeds. Named in reference to the balloons used, Project Loon began as a research and development project by X (formerly Google X) in 2011, but later spun out into a separate company in July 2018. In January 2021, it was announced that the company would be shut down due to lack of profitability. The balloons were maneuvered by adjusting their altitude in the stratosphere to float to a wind layer with the desired speed and direction, using wind data from the National Oceanic and Atmospheric Administration (NOAA). Users of the service connected to the balloon network using a special Internet antenna attached to their building. The signal traveled through the balloon network from balloon to balloon, then to a ground-based station conne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High-altitude Platform Station
A high-altitude platform station (HAPS, which can also mean high-altitude pseudo-satellite or high-altitude platform systems), also known as atmospheric satellite, is a long endurance (aeronautics), endurance, high altitude aircraft able to offer observation or communication services similarly to artificial satellites. Mostly unmanned aerial vehicles (UAVs), they remain aloft through atmospheric lift, either aerodynamic lift, aerodynamic like airplanes, or aerostatic like airships or balloon (aeronautics), balloons. High-altitude long endurance (HALE) military drones can fly above 60,000 ft (18,000 m) over 32 hours, while civil HAPS are radio stations at an altitude of 20 to 50 km above waypoints, for weeks. High-altitude, long endurance flight has been studied since at least 1983, and demonstrator programs since 1994. hydrogen aircraft, Hydrogen and solar power have been proposed as alternatives to conventional engines. Above commercial air transport and wind tur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
