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Free Space Optical(FSO) or Laser communications for ultrafast secure communications from Mars, Moon, Satellites , Aircrafts, and Ships

Broadband Internet, i.e., high-speed public connectivity with a data transfer rate of at least 256 Kbit/s or more in one or both directions, is unavailable in many places and is becoming one of the most impactful problems in the modern world. In some conditions like dense urban development, where the installation of optical fiber lines generates significant costs, access to wireless Internet is very popular.


Regarding data transfer technologies, microwaves have a huge advantage, which is the fact that they go directly through space, reaching their destination without bending their signal. They also do not reflect from the ionosphere, instead of passing through it, so they can be sent from
satellites or local transmitters to any point on Earth. However, maintaining such links is becoming more and more difficult due to the saturation of radio frequencies in large cities, their sensitivity to interference, and the high risk of “leakage” of confidential data Moreover, concerns about high license fees for frequency bands and negative health effects started limiting their wide application.


The deep need for faster and more efficient data transfer gave us newer technologies without the above-mentioned disadvantages. Optical Wireless Communications (OWC) , also called Free-Space Optics (FSO), are devoid of many of the limitations possessed by microwave links. FSO is a wireless optical communication technology that uses the emission of optical radiation in an open space to transmit data between two points without obstructing the line of sight between them. Unlike optical communications over fiber, however, data in OWC is sent over an unguided channel (or medium), such as the atmosphere or the vacuum in space, instead of a guided medium like optical fiber.


Free Space Optical or Laser communications is creating a new communications revolution, that by using visible and infrared light instead of radio waves for data transmission is providing large bandwidth, high data rate, license-free spectrum, easy and quick deployability,  low mass and less power requirement.


It also offers low-cost transmission as against radio frequency (RF) communication technology and fiber optics communication. FSO communication is considered to be one of the key technologies for realizing very-high-speed multi-gigabit-per-second large-capacity communications when fibre optic cable is neither practical nor feasible.


The drawback of the FSO link is that its performance is strongly dependent on atmospheric attenuations. Different atmospheric conditions like snow, fog and rain scatter and absorb the transmitted signal, which leads to attenuation of information signal before receiving at receiver end. As a result of attenuation caused by atmospheric conditions, the range and the capacity of the wireless channels are degraded thereby restricting the potential of the FSO link by limiting the regions and times.


However, FSOC technology has matured with many proven demonstrations: SILEX [the Semiconductor laser Intersatellite Link Experiment], GOLD [the Ground/Orbiter Lasercom Demonstration], and LADEE [NASA’s Lunar Atmosphere and Dust Environment Explorer], and the first operational laser communication service [EDRS, the European Data Relay System, dubbed the SpaceData-Highway].


Free space optical communication (FSO)

In an FSO link, an optical signal is transmitted from an optical transmitter to an optical receiver over the atmosphere or the vacuum in space.
FSO operates on the Line-of-Sight phenomenon, an unobstructed line of sight is required between a transmitter and receiver for FSO communications.

FSO involves the transmission of data through a wireless medium using modulated near infrared light beam (with wavelength between 800 nm-1700 nm) as carrier wave. At the transmitter, the input data is converted into a modulated electrical signal that controls the intensity of light coming out of the laser by controlling the laser current in the driver. The telescope at the transmitter focuses this modulated laser beam at the receiver’s telescope. This optical signal travels through the medium and is received at the receiver’s telescope. The photodetector at the receiver converts this optical signal to an electrical signal, which is then demodulated to retrieve the transmitted data. An optical filter at the receiver eliminates the background solar radiation.


Free-Space Optical links have quite a simple construction, typically consisting of two identical heads enabling duplex data transmission. These heads are connected via interfaces directly to computers or with a telecommunications network.


The source of the optical radiation may be a light-emitting diode, a semiconductor laser, or several lasers. LEDs and semiconductor
lasers are used in wireless optical links for short distances (e.g., inside buildings). On the other hand, FSO links for longer distances mainly use vertical-cavity surface-emitting lasers. Lasers provide more power and faster transmission speeds than LEDs. The advantage of
surface radiating lasers, compared to classic edge lasers, is the symmetrical spatial characteristic of the radiation.


The unique characteristics of laser such as its powerful coherent light beam, the possibility of modulating it at high frequency and the low beam divergence has made it the preferred light source for enhanced FSO applications.


FSO can be further divided into four link sub-types: terrestrial, non-terrestrial (or aerial), space, and deep-space. Examples of terrestrial FSO are building-to-building FSO links. Non-terrestrial FSO links include ground-to-unmanned aerial vehicles (UAVs), ground-to-high altitude platform systems (HAPSs), and HAPS-to-HAPS. Ground-to-satellite, satellite-to-ground, and satellite-to-satellite FSO links are instances of space FSO. Satellite-tosatellite FSO links,  are also referred to as laser inter-satellite links (ISLs). Deep-space FSO can be an FSO link between the Earth and a spacecraft in deep-space like Galileo.


Free Space Optical Communication

Growing employment of laser free space optical communication (FSO)

Both military and civilian users have started planning Laser communication systems from terrestrial short-range systems, to high data rate Aircraft and Satellite communications, unmanned aerial vehicles (UAVs) to high altitude platforms (HAPs), near-space communications for relaying high data rates from moon, and deep space communications from mars.


One major NASA priority is to use lasers to make space communications for both near-Earth and deep-space missions more efficient. Laser wavelengths are 10,000 times shorter than radio waves, allowing data to be transmitted across narrower tighter beams; therefore the energy is not spread out as much as it travels through space.


For example, a typical Ka-Band signal from Mars spreads out so much that the diameter of the energy when it reaches Earth is larger than Earth’s diameter. A typical optical signal, however, will only spread over the equivalent of a small portion of the United States; thus there is less energy wasted. This also leads to reduction in antenna size for both ground and space receivers, which reduces satellite size and mass. “The shorter wavelength also means there is significantly more bandwidth available for an optical signal, while radio systems have to increasingly fight for a very limited bandwidth,” explains NASA.


This technology  is capable of providing promising gigabit Ethernet access for high rise network enterprise or bandwidth intensive applications (e.g., medical imaging, HDTV, hospitals for transferring large digital imaging files or telecommunication) or intra campus connections.


FSO technology provides good solution for cellular carriers using 4G technology to cater their large bandwidth and multimedia requirement by providing a back haul connection between cell towers It can provide a back up protection for fiber based system in case of accidental fiber damage. It is believed that FSO technology is the ultimate solution for providing high capacity last mile connectivity up to residential access.


Commercial telecommunication is a significant driver for LAN-to-LAN, 5G, mobile backhaul, and “last mile” applications. According to Malcolm Watson, a principal research engineer at AVoptics Ltd. (an optical technology SME based in Somerset, England, and Cwmbran, Wales), the major factors driving growth are faster and more secure data transfer, radio frequency (RF) spectrum crunch, and reduced energy consumption.


“Other applications, such as building-to-building high-speed links, commercial aerospace, and within-room communications, are already using or starting to use FSO. FSO can also be used for disaster recovery or temporary building installations, as it can be quick and easy to set up a point-to-point communication link in an environment that is not suitable for laying fiber or using radio [communications],” Watson said.


A growing area for innovation in FSOC is unmanned aircraft systems (UASs) or UAVs operating at very low altitude, typically less than 200 m. Advanced UASs with high-bandwidth data transfer over long ranges are highly desirable. FSO can also be used for disaster recovery or temporary building installations, as it can be quick and easy to set up a point-to-point communication link in an environment that is not suitable for laying fiber or using radio [communications].


The trend toward reductions in the SWaP of optical communications systems has opened up the skies. Laser communications could also benefit a class of missions called CubeSats, which are about the size of a shoebox. These missions are becoming more popular and require miniaturized parts, including communications and power systems.


Compact, lightweight designs can now be fitted into microsatellites, also known as CubeSats, to deliver internet connectivity to remote and rural regions without the need for expensive and difficult-to-lay cabling. Many companies are undertaking networks of satellites in the sky — called constellations — and most look to use laser communications for intersatellite linking to create global canopies of internet coverage that can then be directed down to Earth where needed.


FSO communication link is currently in use for many services at many places.
(a) Outdoor wireless access: it can be used by wireless service providers for communication and it requires no license to use the FSO as it is required in case of microwave bands.
(b) Storage Area Network (SAN): FSO links can be used to form a SAN. It is a network which is known to provide access to consolidated, block level data storage.
(c) Last-mile access: to lay cables of users in the last mile is very costly for service providers as the cost of digging to lay fiber is so high and it would make sense to lay as much fiber as possible. FSO can be used to solve such problem by implementing it in the last mile along with other networks. It is a high speed link. It is also used to bypass local-loop systems of other kinds of networks .
(d) Enterprise connectivity: FSO systems are easily installable. This feature makes it applicable for interconnecting LAN segments to connect two buildings or other property.
(e) Fiber backup: FSO can also be applicable in providing a backup link in case of failure of transmission through fiber link .
(f) Metro-network extensions: it can be used in extending the fiber rings of an existing metropolitan area. FSO system can be deployed in lesser time and connection of the new networks and core infrastructure is easily done. It can also be used to complete SONET rings.
(g) Backhaul: it can be helpful in carrying the traffic of cellular telephone from antenna towers back to the PSTN with high speed and high data rate. The speed of transmission would increase.
(h) Service acceleration: it can also be used to provide instant service to customers when their fiber infrastructure is being deployed in the mean time.
(i) Bridging WAN Access: FSO is beneficial in WAN where it supports high speed data services for mobile users and small satellite terminals and acts as a backbone for high speed trunking network.
(j) It can be used to communicate between point-to-point links, for example, two buildings, two ships, and point-to-multipoint links, for example, from aircraft to ground or satellite to ground, for short and long reach communication .
(k) Military access: as it is a secure and undetectable system it can connect large areas safely with minimal planning and deployment time and is hence suitable for military applications


NASA’s Lunar Laser Communication Demonstration (LLCD) and Laser Communications Relay Demonstration (LCRD)

We communicate with robotic missions through radio signals. It requires a network of large radio antennas to do this. Spacecraft have relatively weak receivers, so you need to beam a strong radio signal to them. They also transmit relatively weak signals back. You need a large sensitive radio dish to capture the reply. For spacecraft beyond the orbit of Earth, this is done through the Deep Space Network (DSN), which is a collection of radio telescopes custom designed for the job.


The only major crewed mission we currently have is the International Space Station (ISS). Since the ISS orbits only about 400 kilometers above the Earth, it’s relatively easy to send radio signals back and forth. But as humans travel deeper into space, we’ll require a Deep Space Network far more powerful than the current one. The DSN is already being pushed to its data limits, given the large number of active missions. Human missions would require orders of magnitude more bandwidth.


In 2013, NASA’s Lunar Laser Communications Demonstration (LLCD) had demonstrated error-free communication from the Moon to the Earth under all conditions, including during broad daylight and even when the Moon was within 3° of the Sun as seen from Earth. It also proved that a space-based laser communications system was viable and that the system could survive both launch and the space environment.


NASA’s Lunar Laser Communication Demonstration (LLCD) used a pulsed laser beam to transmit data from the Moon to Earth at a record-breaking download rate of 622Mb/s. The space laser terminal employed a 0.5W IR laser at 1.55 microns (which is eye-safe as well as invisible to the eye) and 4in (10.7cm) telescope to transmit toward the selected ground terminal. The downlink beam is received by an array of telescopes that are coupled to novel and highly sensitive superconducting nanowire detector arrays that convert the photons in the beam to bits of data.


US-based LGS Innovations, has won a contract from NASA to provide a laser transmitter for a first-of-a-kind space mission. The Herndon, Virginia, company’s photonics technology will be one of the key elements in a high-bandwidth optical communications link that will beam data and high-resolution imagery back to Earth from a craft orbiting around an unusual metal asteroid. A part of what is known is full as NASA’s Deep Space Optical Communications (DSOC) project, the laser transmitter will fly on the mission to the asteroid “Psyche” as a technology demonstration.


The Goddard team is now planning a follow-on mission called the Laser Communications Relay Demonstration (LCRD) that proposes to revolutionize the way we send and receive data, video and other information, using lasers to encode and transmit data at rates 10 to 100 times faster than today’s fastest radio-frequency systems, using significantly less mass and power.  It will fly as a commercial satellite payload in 2019. It consists of two optical communications terminals in space and will enable real-time forwarding and storage of data up to 1.25 Gbps (coded) / 2.880 Gbps (uncoded).


Mission operators at ground stations in California and Hawaii will test its invisible, near-infrared lasers, beaming data to and from the satellite as they refine the transmission process, study different encoding techniques and perfect tracking systems.While in operation, LCRD will also enable the gathering of information about the longevity and durability of space-based optical systems and their hardware, as well as ensuring the accuracy of the lasers that carry messages to the ground. They also will study the effects of clouds and other disruptions on communications, studying mitigating solutions including relay operations in orbit or backup receiving stations on the ground.


NASA is now planning laser communications from Mars, it is developing new optical communications system, that will reduce the time required to transmit high resolution images from Mars from 90 minutes to few minutes. The new optical communications system that NASA plans to demonstrate in 2016 will even allow the streaming of high-definition video from distances beyond the Moon.


The Deep Space Optical Communications project is developing three key technologies essential for operational deep space optical communications, Spacecraft disturbance isolation platform, Photon counting receiver for spacecraft optical transceiver consisting of radiation-tolerant indium gallium arsenide phosphide (InGaAsP) detector and superconducting photon counting detectors for the Earth-based optical receivers.


The team at Glenn is developing an idea called Integrated Radio and Optical Communications (iROC) to put a laser communications relay satellite in orbit around Mars that could receive data from distant spacecraft and relay their signal back to Earth. The system would use both RF and laser communications, promoting interoperability amongst all of NASA’s assets in space. By integrating both communications systems, iROC could provide services both for new spacecraft using laser communications systems and older spacecraft like Voyager 1 that use RF.


NASA’s up and coming Psyche mission to explore a unique metal asteroid orbiting the Sun between Mars and Jupiter, will also test new communication hardware that uses lasers instead of radio waves.  In parallel with a more conventional X-band microwave link, it will send engineering and science data from the Psyche Spacecraft and is said to be the first such laser transmitter to support deep-space, high-bandwidth optical communication.


“Future deep space exploration missions, both manned and unmanned, will require high-bandwidth communications links to ground stations on Earth to support advanced scientific instruments, high-definition video, and high-resolution imagery,” states LGS, adding that its transmitter will enable much faster communication and help improve the efficiency of future solar system exploration missions


Laser communications  from Satellites for global internet connectivity

Due to their smaller size, weight, volume, and power requirement, FSO terminals require less onboard satellite resources and can be
easily integrated into satellite platforms. The smaller form factor of FSO terminals also helps in reducing satellite launching and deployment costs. According to one analysis, compared to  RF links operate in Ka and mm-wave bands, at a data rate of 2.5 Gbps over an inter-satellite distance of 5,000 km, the RF ISL in either Ka or mm-wave bands requires at least 19 times the antenna diameter, and more than twice the onboard power and mass compared to an FSO ISL.



US-based Aerospace has demonstrated a new laser communication system using two low-Earth-orbiting optical communications and sensor demonstration (OCSD) CubeSats named AeroCube-7B and Aerocube-7C. During the demonstration, the CubeSats transmitted data at a rate of 100mbps, which is 50 times higher than the typical communication systems carried out by satellites of this size.


The OCSD mission is funded and managed by Nasa’s Space Technology Mission Directorate Small Spacecraft Technology programme, while Aerospace designed and built the OCSD spacecraft. Representing the first of its kind mission performed by small satellites, including CubeSats, the demonstration involved the use of free-space laser communication systems that are smaller, lighter and offer higher data rates and more security compared to the current radio frequency systems.


According to Aerospace, each of the OCSD satellite’s laser is hard-mounted to allow the entire spacecraft to rotate while pointing the laser. This attitude control system eliminated the use of beam steering mirrors and harnessed a highly accurate control system to point the satellite while downloading data. The system includes tiny star trackers and is designed to allow the spacecraft to point to an accuracy of 0.025°. Aerospace also conducted a proximity manoeuvre to bring the OCSD satellites within 20ft of distance before the demonstration. The 1.5 unit OCSD pair used onboard GPS receivers determined the gap between them, as well as a new water-based propulsion system designed by Aerospace to control their movement.


Facebook aims to use a mix of solar-powered aircraft and low-orbit satellites to beam signals carrying the internet to hard-to-reach locations. ‘As part of our efforts, we’re working on ways to use drones and satellites to connect the billion people who don’t live in range of existing wireless networks,’ said Mark Zuckerberg. The drones, flying at 65,000ft (19,800 metres), will be capable of staying in the air for months. ‘Our Connectivity Lab is developing a laser communications system that can beam data from the sky into communities. ‘This will dramatically increase the speed of sending data over long distances.


It is proposed that for sub-urban areas in limited geographical regions, solar-powered high altitude drones will be used to deliver reliable internet connections via FSO links. For places where deployment of drones is uneconomical or impractical (like in low population density areas), LEO and GEO satellites can be used to provide internet access to the ground using FSO.


Freespace laser communications  was used to send data reliably between balloons flying on the stratospheric winds in Project Loon. Now loon team is  working with AP State FiberNet, a telecom company in Andhra Pradesh, a state in India which is home to more than 53 million people. Less than 20% of residents currently have access to broadband connectivity, so the state government has committed to connecting 12 million households and thousands of government organizations and businesses by 2019 — an initiative called AP Fiber Grid.


AP State FiberNet announced that they’ll be rolling out two thousand FSOC links created by  team at X. These FSOC links will form part of the high-bandwidth backbone of their network, giving them a cost effective way to connect rural and remote areas across the state. The links will plug critical gaps to major access points, like cell-towers and WiFi hotspots, that support thousands of people.


Intersatellite links

Many companies are undertaking networks of satellites in the sky — called constellations — and most look to use laser communications for intersatellite linking to create global canopies of internet coverage that can then be directed down to Earth where needed. One such example is Mynaric, a German company specializing in laser communications for satellite networks, airborne platforms, and their respective ground terminals. Mynaric, which has its U.S. headquarters in Los Angeles, was founded by former employees of the German Aerospace Center (DLR).


“From a strictly commercial point of view, the main drivers are the several companies who recognize the importance of laser communications in establishing effective backbone connectivity in space,” said Markus Knapek, founder of Mynaric. “SpaceX is probably the highest profile of these and has already trialed lasercom [laser-based communications] between two prototype satellites launched early in 2018. The eventual constellation — planned to consist of just under 12,000 satellites — will employ laser intersatellite links.”


For low-Earth-orbit networks, each satellite will host four laser communications terminals: one facing the front, one facing the back, and one on each side. These will connect the satellite to both an intra- and an intersatellite plane. In the upper atmosphere, localized meshed networks of drones or high-altitude platforms (pseudo satellites) form miniconstellations.


Maneuvering these miniconstellations above areas affected by natural disasters, for example, can help to reestablish emergency links. An example of this occurred in June 2019 when a magnitude 8 earthquake struck Peru and nearby Ecuador. Within 48 hours, cellphone connection was returned to the stricken area thanks to a network of air balloons powered by solar panels and armed with antennae that could connect to ground stations.


With demonstrations of the technology heralded a success, market research experts SpaceWorks Enterprises Inc. estimates that about 700 communications nano/microsatellites will be launched over the next five years. These will be used to serve and support the rapidly growing Internet of Things as well as the machine-to-machine market. Practical implementations of current optical communications systems for small satellite applications may reach data rates of about 10 Gb/s, with a terminal weight on the order of 5 kg and a power consumption of about 50 W


World record in free-space optical communications

ADVA (FSE: ADV) announced in May 2018,  that they together with the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt – DLR),  have set a new data transmission record for free-space laser communications. The trial, which emulated a ground to a geostationary satellite link, succeeded in transmitting 13.16Tbit/s of data over a distance of 10.45km – a vital step towards delivering high-speed broadband to rural and underdeveloped areas.


The demonstration involved a laser connection between a ground station in Weilheim, Germany, and a mock satellite more than 10km away on the mountain Hohenpeißenberg. The distance and speed both break new ground with the figure of 13.16Tbit/s nearly eight times the DLR’s previous record. At this data rate, all printed books in the world could be transmitted in about half a minute. The feat was made possible by ADVA’s technology including its QuadFlex™ line cards. These support high-order coherent modulation schemes and enabled each wavelength to carry 200Gbit/s payload data using dual-polarization 16QAM (quadrature amplitude modulation) and strong soft-decision forward error correction. Atmospheric turbulence in the terrestrial link was equivalent to that experienced in a worst-case scenario between ground and geostationary satellites.


The ADVA FSP 3000 CloudConnect™ platform was crucial to the trial, transporting huge amounts of data and managing extreme levels of atmospheric turbulence. DLR developed the free-space terminal technology that coupled a fast varying, distorted wavefront into a fiber with a cross-section smaller than a human hair. The record-breaking trial is key to DLR’s aim of enabling broadband coverage based on affordable satellite links.


We have set ourselves the goal of enabling Internet access at high data rates outside major cities, and want to demonstrate how this is possible using satellites,” explains Christoph Günther, Director of the DLR Institute of Communications and Navigation. Fibre-optic links and other terrestrial systems offer high transmission rates, but are available predominantly in densely populated regions.


Outside of the metropolitan centres a broadband supply via geostationary satellites is possible. Scientists  as part of the DLR THRUST (Terabit-throughput optical satellite system technology) project, satellites should be connected to the terrestrial Internet via a laser link. The envisaged data throughput is more than one terabit per second. Communication with the users is then carried out in the Ka-band, a standard radio frequency for satellite communications.


Europe’s Global Laser Communications System

The first high capacity space-to-ground laser communication system is to be installed on the Bartolomeo platform of the International Space Station (ISS) as part of a collaboration between Airbus Defence and Space, the Institute of Communications and Navigation of DLR (German Aerospace Center) and Tesat-Spacecom GmbH & Co. KG. The system called OSIRIS will provide direct to earth (DTE) technology with a data rate of 10 Gbps over range of about 1.500 km.


The European Space Agency (ESA) and partner Airbus Defence and Space are aiming to build out the European Data Relay System (EDRS) into a global laser communications network by 2020 and hope that the system will become an international standard. Sentinel satellites 1A, 1B, 2A and 2B all have Laser Communication Terminals (LCT) payloads.


ESA and Airbus completed a major test of the EDRS system in late 2014, linking the Sentinel 1A satellite built by Thales Alenia Space with the Airbus-built Alphasat satellite via Laser Communication Terminals (LCTs). The test beamed images from Sentinel 1A, which circles the planet at 700 kilometers in Low Earth Orbit (LEO) to Alphasat 36,000 kilometers up in Geostationary Earth Orbit (GEO) and back to the ground. Tesat boasts it’s point-to-point data transfer covers about 28000 miles with transfer rate of 5 Gigabits per sec.


“[Sentinel 1A] produces around 1.8 terabytes of raw data every single day, and when we process this data it is even three terabytes, more or less, on average we produce everyday. In 2017 we will have seven Sentinels working and roughly seven times the amount of data to download. Four of these Sentinels will have a laser communication terminal and can use EDRS,” he said.


Stefan Klein, head of aviation division General Atomics, Spezialtechnik, said his company is eager to use EDRS laser communications for its Unmanned Aerial Vehicles (UAVs). Today the company’s drones get up to 40 hours of flight without refueling, and require real-time data through secure communications. The company plans to build LCT payloads to leverage EDRS by the end of the decade.

Laser Light Communications’s Optical Satellite Systems

Xenesis, ATLAS Space Operations, and Laser Light Communications announced today they have joined forces in a Service-Level Solution – Empower Space Alliance™. Empower Space™ will provide a turnkey direct optical data distribution service from spacecraft to customer locations, worldwide. Empower Space™ intends to serve LEO, MEO, GEO, Cislunar, and Deep Space capability with standardized interoperability, robust data capacity and unprecedented access to customer locations worldwide. Space data platforms will now have a choice between relying on legacy radio frequency transmission and distribution, or high capacity & low cost all optical “direct delivery” of their data to its ultimate distribution…on a single network.


The world’s first optical wave satellite communications has been planned by Laser Light Communications, intending to deploy it in the first quarter of 2017.The company plans on creating a 12-satellite constellation in MEO with an operating system capacity of 4.8 terabytes/sec and satellite-to-satellite optical crosslinks and satellite-to-ground optical up/down links of 200 gigabytes/sec. The company envisions integrating the Optical Satellite System with existing terrestrial and undersea fiber optic levels.


DISA has signed a Cooperative Research and Development Agreement with Laser Light Communications to evaluate the feasibility of the underlying technology and the future potential of the all-optical system for DOD missions. The laser communications is attractive for defence of its high bandwidth and freedom from issues like spectrum allocation or mutual interference due to satellite spacing. The system is also more secure because enhanced resistance of optical communication systems from interception and jamming.


Aircraft to Ground Communications

Free-space optical (FSO) communication links of 1Gbps between aircraft and ground stations have been demonstrated by Christopher Schmidt and others from Institute of Communication and Navigation, German Aerospace Center. This ultrafast movement of information, of high data volumes which uses high-resolution sensor systems, has particular applications for disaster management, monitoring natural events, and traffic observation.


Their system consists of Optical transmitter, called Free-space Experimental Laser Terminal II (FELT II), installed in Do228 aircraft consisting of two-stage tracking system, an inertial measurement unit (for velocity and orientation), the optical bench inside the cabin of the aircraft, and a dome-shaped assembly below the cabin.


For data reception they have designed transportable optical ground station (TOGS), that consist of a pneumatically deployable Ritchey-Chrétien-Cassegrain telescope with a main mirror diameter of 60cm. TOGS is equipped with an optical tracking system, dual-antenna global positioning system and an inclination sensor to determine its own location, heading, and calibration, and it has supports to enable leveling of the station.


APL Demonstrates High-Bandwidth Communications Capability at Sea

Navy ships typically use RF systems to communicate — but the Navy also looks for alternative means of communication in case, for technical, operational or environmental reasons, radio transmission isn’t available. “Naval platforms increasingly need to operate effectively in reduced-RF or emission control conditions while maintaining their tactical advantage and situational awareness,” noted Juarez.


Free-space optical communication systems — which make use of wireless transmission to deliver optical data signals at high bit rates — offer a compelling adjunct communications capability to conventional RF and microwave communications by providing secure high data rates outside the conventional RF spectrum.


Commercial FSO systems exist but typically don’t address defense needs, Juarez said, “specifically in terms of system mobility, link range, and data rate while operating in the highly scintillated terrestrial environment, especially close to the water.” FSO demonstration systems previously built for terrestrial defense applications have been too large, or lacked the mobility, data rates, or ranges to be practical on naval platforms.


In 2017, A team of engineers from the Johns Hopkins University Applied Physics Laboratory (APL), in Laurel, Maryland, has successfully demonstrated a high-bandwidth, free-space optical (FSO) communications system between two moving ships, proving operational utility of FSO technology in the maritime environment. Juan Juarez, the technical lead for the team developing the technology, said APL is the first organization to successfully operate such a high-capacity optical communications capability — up to 10 gigabits per second — on the move, on board ships at sea, and in challenging near-shore environments.


“We demonstrated bandwidths that were several orders of magnitude higher than all current radio frequency [RF] communications capability on Navy vessels, and at longer ranges than previously demonstrated FSO technology for maritime applications,” Juarez said. “This is the equivalent to having up to 2,000 users simultaneously watching high-definition video streams across the optical link.”

APL’s system overcomes many of these challenges. The first week of testing was ship-to-shore, from the motor vessel (M/V) Merlin off the coast of Naval Base Point Loma, San Diego, to the 3rd Fleet Headquarters parking lot. The team achieved more than 14 hours of link-up time, including during 4- to 6-foot high seas; 1–2 gigabits of error-free data transport at ranges greater than 25 kilometers; voice communications at greater than 35 kilometers; chat messaging out to 45 kilometers, the maximum available line of sight; and repeatable, semiautomatic reacquisitions over the entire line-of-sight range.


Also during that first week, Vice Adm. Nora Tyson, commander of U.S. 3rd Fleet, visited the land-based testing site and was briefed by the ship-based team over the optical link — the first time a three-star admiral held a video teleconference over an optical link. “Weather conditions during the two weeks of testing were typical of San Diego’s ‘June Gloom’ and gave the APL team plenty of opportunities to show that our FSO technology can operate even through some levels of fog and haze,” Juarez said. “While the fog layer was present, links of over 10 kilometers were achieved, even though visibility at times was reduced to 2–3 kilometers.”


During the second week of testing, the second set of hardware was installed onboard the Sea Hunter, an autonomous continuous trail unmanned vessel (ACTUV) developed by the Defense Advanced Research Projects Agency (DARPA) and the Office of Naval Research. The Sea Hunter was temporarily manned by a six-person Space and Naval Warfare Command crew in addition to the APL test team for this demonstration.


Multiple links between the two ships were achieved in 3- to 5-foot swells, over 10 kilometers in range, with ACTUV Sea Hunter going 24 knots and M/V Merlin going 12 knots in a “V” formation that allowed the ships to quickly separate from one another, while maintaining the links at varying speeds and motions. “Despite seas that had both ships rolling with the swells, the link stayed solid,” Juarez said. The FSO equipment experienced significant sea spray, and the omnipresent San Diego marine layer fog added an additional challenge to the ship-to-ship linkages. Nonetheless, first-time data rates as high as 7.5 gigabits were achieved over a link between two vessels.



 Optical LAN

Short range Laser communications has also started being utilized for tasks such as connecting campus or office buildings when an obstruction such as a river or road makes laying fiber infeasible. Northern Storm, a US based enterprise has partnered with Mostcom in Eastern Europe have developed NS10G system, that can provide 10 gig throughput upto 1 Km at the price is 1/4th the installed cost of a 10 Gig fiber line.


By using an optical transmitter and receiver to process the data through the air, the need for cables is eliminated. The advantage of FSO is that it supports equipment from a variety of vendors and requires no security software upgrades. British startup Cablefree offers a wide range of free space communication solutions for high-performance wireless connectivity with a maximum network transmission capacity of 10Gbps. Their FSO technology is actively used in a wide range of outdoor applications.


Using FSO to connect networks within enterprises offers advantages such as not paying fees for leased-lines and fiber cables, resulting in greater savings, especially for larger enterprises. It is more secure than transmitting data over public networks and allows for multiple gigabyte transmissions simultaneously. The US-based startup Lightpointe specializes in point-to-point radio-based FSO technology. Their wireless bridge is designed to connect buildings and organizations at high speeds without having to rely on any fiber lines or public network infrastructure, which results in low monthly costs and high network security.


Collinear – Backhaul

As the communication infrastructure grows and expands towards 5G, each stage brings with it an exponential growth in the data that is transmitted over the network. The communication from the cell tower to the rest of the world, or the core network, is an important link in determining the speed of data transmission. By increasing the speed at which data is transferred within the network allows devices to communicate with each other in real-time, which can further enhance smart city applications. The US-based startup Collinear develops a unique backhaul architecture which is robust and highly scalable. Their Hybrid Free Space Optic (HFSO) and wireless radio frequencies can drastically optimize the transmission of data for better real-time communication and have a more efficient cost-per-bit of transmission.


Market growth

Free Space Optics (FSO) Communication Market size is set to grow substantially from 2019 to 2025 led by its wide range of usability in several networking scenarios such as Outdoor Wireless Access, Storage Area Network, enterprise connectivity, Metro-Network Extensions, and military access.  The requirement of low initial investment, easy installation features, and no use of fibers provide advantages over traditional optical system, supporting the free space optics communication market demand. Rapid increase in the need for digital connectivity in the commercial & residential sector is fueling the market. In wireless optical communication technology, transmission of information from point-to-point is done using a highly narrow beam, which ensures the security of information being transferred.


The free space optics communication market is witnessing significant growth owing to the increasing innovation in the technology and communication sector. The recent development in the FSO communication market includes the introduction of optical angular momentum, which uses twisted photons for transmission. Twisted photons can carry additional information resulting in much higher-bandwidth communications technology. This technology is immune to radio frequency interference and uses less power for transmission. In comparison to other remote transmission innovations or RF, information transmitted through free space optics is considered to be more secure.


Factors driving the growth of the FSO market include last-mile connectivity, no licensing, and alternative solution to overburdened RF technology for outdoor networking. The visible light communication (VLC) market is expected to grow from USD 2.56 billion in 2018 to USD 75.00 billion by 2023, at a CAGR of 96.57% between 2018 and 2023. Major factors driving this growth are faster and safer data transfer, RF spectrum bandwidth crunch, and less energy consumption.


A surge in demand for high bandwidth and increasing application of free space optical technology in military environments is strongly driving the growth of the free space optics market. Bandwidth usage is experiencing unprecedented growth and the demand for bandwidth is not likely to slow down in the coming years. Free space optical communication is a viable solution for various military applications and the most promising military environments where FSO technology can be used include military bases, in between bases where bases are co-located within 2-4 km of one another, ship to shore communications, and ship to ship communications. In addition to these factors, the incorporation of free space optics in 3G and 4G networks is triggering the market growth. Furthermore, quicker time to market and reduced costs associated with free space optics technology is boosting the market growth. The conjoint effect of all these drivers is thus set to bolster the growth of the global free space optics (FSO) communication market during the forecast period.


The Asia Pacific region is expected to dominate the free space optics communication market over the forecast timeline owing to the rapid expansion of the IT & telecom industry. Rapid technological advancements in this region and increasing innovation in the communication & technology sector in India and China are supporting the market growth. Moreover, the collaboration of federal space entities, such as National Aeronautics & Space Administration (NASA) and European Space Agency (ESA), as an expansion of the space communication network is likely to propel the growth of the FSO communication market.


Players operating in the free space optics communication market include Anova Technologies, General Electronics, Fujitsu Ltd., Harris Corporation, Wireless Excellence Ltd., Lightbee Corp., Trimble Hungary, and Outstanding Technology. Several players in the market adopted growth and development strategies, such as new product launches & innovations, mergers, acquisitions, partnerships, and collaborations, to strengthen the product portfolio and gain high revenues. For instance, in March 2019, Trimble Hungary introduced new TMT service connect module to enhance the efficiency of transportation facilities.


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