BREAKING NEWS
Cloud Server Hosting For Online Businesses
Inexpensive SEO Services
Benefits of Wanting to play Free Online Slot machines
Laser communication in space

Summary

Laser communication in space is the use of free-space optical communication in outer space. Communication may be fully in space (an inter-satellite laser link) or in a ground-to-satellite or satellite-to-ground application. The main advantage of using laser communications over radio waves is increased bandwidth, enabling the transfer of more data in less time.

A diagram showing two solar-powered satellites communicating optically in space via lasers.

In outer space, the communication range of free-space optical communication[1] is currently of the order of hundreds of thousands of kilometers,[2]. Laser-based optical communication has been demonstrated between the Earth and Moon and it has the potential to bridge interplanetary distances of millions of kilometers, using optical telescopes as beam expanders.[3]

Demonstrations and testsEdit

Before 1990Edit

On 20 January 1968, the television camera of the Surveyor 7 lunar lander successfully detected two argon lasers from Kitt Peak National Observatory in Arizona and Table Mountain Observatory in Wrightwood, California.[4]

1991-2000Edit

In 1992, the Galileo probe proved successful one-way detection of laser light from Earth as two ground-based lasers were seen from 6,000,000 km (3,700,000 mi) by the out-bound probe.[5]

The first successful laser-communication link from space was carried out by Japan in 1995 between the JAXA's ETS-VI GEO satellite and the 1.5 m (4 ft 11 in) National Institute of Information and Communications Technology (NICT)'s optical ground station in Tokyo achieving 1 Mbit/s.[6]

2001-2010Edit

In November 2001, the world's first laser intersatellite link was achieved in space by the European Space Agency (ESA) satellite Artemis, providing an optical data transmission link with the CNES Earth observation satellite SPOT 4.[7] Achieving 50 Mbps across 40,000 km (25,000 mi), the distance of a LEO-GEO link.[8] Since 2005, ARTEMIS has been relaying two-way optical signals from KIRARI, the Japanese Optical Intersatellite Communications Engineering Test Satellite.[9]

In May 2005, a two-way distance record for communication was set by the Mercury laser altimeter instrument aboard the MESSENGER spacecraft. This diode-pumped infrared neodymium laser, designed as a laser altimeter for a Mercury orbit mission, was able to communicate across a distance of 24,000,000 km (15,000,000 mi), as the craft neared Earth on a fly-by.[10]

In 2006, Japan carried out the first LEO-to-ground laser-communication downlink from JAXA's OICETS LEO satellite and NICT's optical ground station.[11]

In 2008, the ESA used laser communication technology designed to transmit 1.8 Gbit/s across 40,000 km (25,000 mi), the distance of a LEO-GEO link. Such a terminal was successfully tested during an in-orbit verification using the German radar satellite TerraSAR-X and the American Near Field Infrared Experiment (NFire) satellite. The two Laser Communication Terminals (LCT)[12] used during these tests were built by the German company Tesat-Spacecom,[13] in cooperation with the German Aerospace Center (DLR).[14]

2011-2020Edit

 
Depiction of the optical module of the LLCD
 
The successful OPALS experiment

In January 2013, NASA used lasers to beam an image of the Mona Lisa to the Lunar Reconnaissance Orbiter (LRO) roughly 390,000 km (240,000 mi) away. To compensate for atmospheric interference, an error correction code algorithm similar to that used in CDs was implemented.[15]

In September 2013, a laser communication system was one of four science instruments launched with the NASA LADEE (Lunar Atmosphere and Dust Environment Explorer) mission. After a month-long transit to the Moon and a 40-day spacecraft checkout, the laser communications experiments were performed over three months during late 2013 and early 2014.[16] Initial data returned from the Lunar Laser Communication Demonstration (LLCD) equipment on LADEE set a space communication bandwidth record in October 2013 when early tests using a pulsed laser beam to transmit data over the 385,000 km (239,000 mi) between the Moon and Earth passed data at a "record-breaking download rate of 622 megabits per second (Mbps)",[17] and also demonstrated an error-free data upload rate of 20 Mbit/s from an Earth ground station to LADEE in lunar orbit. The LLCD is NASA's first attempt at two-way space communication using an optical laser instead of radio waves, and is expected to lead to operational laser systems on NASA satellites in future years.[17]

In November 2013, laser communication from a jet platform Tornado was successfully demonstrated for the first time. A laser terminal of the German company Mynaric (formerly ViaLight Communications) was used to transmit data at a rate of 1 Gbit/s over a distance of 60 km and at a flight speed of 800 km/h. Additional challenges in this scenario were the fast flight maneuvers, strong vibrations, and the effects of atmospheric turbulence. The demonstration was financed by EADS Cassidian Germany and performed in cooperation with the German Aerospace Center DLR.[18][19][20]

In November 2014, the first ever use of gigabit laser-based communication as part of the European Data Relay System (EDRS) was carried out.[21] Further system and operational service demonstrations were carried out in 2014. Data from the EU Sentinel-1A satellite in LEO was transmitted via an optical link to the ESA-Inmarsat Alphasat in GEO and then relayed to a ground station using a conventional Ka-band downlink. The new system can offer speeds up to 7.2 Gbit/s.[22] The Laser terminal on Alphasat is called TDP-1 and is still regularly used for tests. The first EDRS terminal (EDRS-A) for productive use has been launched as a payload on the Eutelsat EB9B spacecraft and became active in December 2016.[23] It routinely downloads high-volume data from the Sentinel 1A/B and Sentinel 2A/B spacecraft to ground. So far (April 2019) more than 20000 links (11 PBit) have been performed.[24]

In December 2014, NASA's Optical Payload for Lasercomm Science (OPALS) announced a breakthrough in space-to-ground laser communication, downloading at a speed of 400 megabits per second. The system is also able to re-acquire tracking after the signal is lost due to cloud cover.[25] The OPALS experiment was launched on 18 April 2014 to the International Space Station (ISS) to further test the potential for using a laser to transmit data to Earth from space.[26]

The first LEO-to-ground lasercom demonstration using a japanese microsatellite (SOCRATES) was carried out by NICT in 2014,[27] and the first quantum-limited experiments from space were done by using the same satellite in 2016.[28]

In February 2016, Google X announced to have achieved a stable laser communication connection between two stratospheric balloons over a distance of 100 km (62 mi) as part of Project Loon. The connection was stable over many hours and during day and nighttime and reached a data rate of 155 Mbit/s.[29]

In June 2018, Facebook's Connectivity Lab (related to Facebook Aquila) was reported to have achieved a bidirectional 10 Gbit/s air-to-ground connection in collaboration with Mynaric. The tests were carried out from a conventional Cessna aircraft in 9 km (5.6 mi) distance to the optical ground station. While the test scenario had worse platform vibrations, atmospheric turbulence and angular velocity profiles than a stratospheric target platform the uplink worked flawlessly and achieved 100% throughput at all times. The downlink throughput occasionally dropped to about 96% due to a non-ideal software parameter which was said to be easily fixed.[30]

In April 2020, the Small Optical Link for International Space Station (SOLISS) created by JAXA and Sony Computer Science Laboratories, established bidirectional communication between the ISS and a telescope of the National Institute of Information and Communications Technology of Japan.[31]

In 29 November 2020, Japan launched the inter-satellite optical data relay geostationary orbit satellite with high speed laser communication technology, named LUCAS (Laser Utilizing Communication System).[32][33]

2021-presentEdit

In June 2021, the U.S. Space Development Agency launched a two 12U CubeSats aboard a SpaceX Falcon 9 Transporter-2 rideshare mission to Sun-synchronous orbit. The mission is expected to demonstrate laser communication links between the satellites and a remotely controlled MQ-9 Reaper.[34]

Future missionsEdit

On December 7, 2021 NASA's Laser Communications Relay Demonstration (LCRD) launched as part of USAF STP-3, to communicate between geosynchronous orbit and the Earth's surface.

Laser communications in deep space will be tested on the Psyche mission to the main-belt asteroid 16 Psyche, planned to launch in 2022.[35] The system is called Deep Space Optical Communications (DSOC),[36] and is expected to increase spacecraft communications performance and efficiency by 10 to 100 times over conventional means.[36][35]

Japan's National Institute of Information and Communications Technology (NICT) will demonstrate in 2022 the fastest bidirectional lasercom link between the geosynchronous orbit and the ground at 10 Gbit/s by using the HICALI (High-speed Communication with Advanced Laser Instrument) lasercom terminal on board the ETS-9 (Engineering Test Satellite IX) satellite,[37] as well as the first intersatellite link at the same high speed between a CubeSat in LEO and HICALI in GEO one year later.[38]

Commercial useEdit

Corporations like SpaceX, Facebook and Google and a series of startups are currently pursuing various concepts based on laser communication technology. The most promising commercial applications can be found in the interconnection of satellites or high-altitude platforms to build up high-performance optical backbone networks. Other applications include transmitting large amounts of data directly from a satellite, aircraft or unmanned aerial vehicle (UAV) to the ground.[39]

OperatorsEdit

Multiple companies want to use laser communication in space for satellite constellations in low Earth orbit to provide global high-speed Internet access. Similar concepts are pursued for networks of aircraft and stratospheric platforms.

Project Project Concept Environment Scenario Data rate Supplier Status
European Data Relay System (EDRS)[a] Data relay to GEO satellites from LEO Earth observation satellites and for intelligence, surveillance and reconnaissance missions GEO, LEO Space-to-space 1.8 Gbit/s Tesat-Spacecom[40] Active
Laser Light Communications Satellite constellation for global telecommunications building an optical backbone network in space MEO Space-to-space, Space-to-ground 100 Gbit/s[41] Ball Aerospace & Technologies[42] Development
SpaceLink Data relay services from MEO for LEO satellites MEO, LEO Space-to-space Mynaric[43] Development
WarpHub InterSat Inter satellite data relay for LEO Earth observation satellites, space-to-ground communication uses RF. MEO Space-to-space 1 Gbit/s[44] Development
Analytical Space[45] In-space hybrid RF/optical data relay network for Earth observation satellites LEO Space-to-ground Development
BridgeComm[46] Direct data downstream from LEO Earth observation satellites to the ground LEO Space-to-ground 1 Gbit/s Surrey Satellite Technology[47] Development
Cloud Constellation Secure data storage on satellites and secure intercontinental connections LEO Space-to-space Mynaric[48] Development
SDA National Defense Space Architecture Proliferated LEO constellation consisting of multiple layers serving needs of the U.S. Department of Defense (DoD).[49] LEO Space-to-space Development
DARPA Blackjack Risk reduction efforts to test the viability of new military space capabilities provided by emerging commercial LEO constellations[49] LEO Space-to-space Mynaric,[50] SA Photonics[51] Development
LeoSat Satellite mega-constellation for global telecommunications LEO Space-to-space Thales Alenia Space[52] Terminated[53]
OneWeb Gen Two[54] Satellite mega-constellation for global telecommunications LEO Space-to-space Development
Starlink Satellite mega-constellation for global telecommunications LEO Space-to-space 100 Gbit/s[55] SpaceX / Starlink Active[56][57]
Telesat LEO constellation Satellite mega-constellation for global telecommunications LEO Space-to-space Development
Google Loon[29] Telecommunications for rural and remote areas provided by a network of stratospheric balloons Stratosphere Air-to-air 0.155 Gbit/s Terminated
Facebook Aquila[58] Telecommunications for rural and remote areas provided by a network of high-altitude platforms Stratosphere Air-to-air, Air-to-ground 10 Gbit/s Mynaric[30] Terminated
  1. ^ EDRS is a Public–private partnership between Airbus and the European Space Agency.

SuppliersEdit

A substantial market for laser communication equipment may establish when these projects will be fully realized.[59] New advancements by equipment suppliers is enabling laser communications while reducing the cost. Beam modulation is being refined, as its software, and gimbals. Cooling problems have been addressed and photon detection technology is improving.[citation needed] Currently active notable companies in the market include:

Company Product status
Ball Aerospace and Honeywell[60] [1] in development
Ecuadorian Space Agency[61][62][2] TRL9 - in production
Hensoldt [3]
LGS Innovations[63]
Mostcom JSC [4] in development
Mynaric [5]
Sony[64] in development
Surrey Satellite Technology in development
Tesat-Spacecom %5B6%5D in production
Thales Alenia Space
Transcelestial[65] [7] in development

Secure communicationsEdit

Secure communications have been proposed using a laser N-slit interferometer where the laser signal takes the form of an interferometric pattern, and any attempt to intercept the signal causes the collapse of the interferometric pattern.[66][67] This technique uses populations of indistinguishable photons[66] and has been demonstrated to work over propagation distances of practical interest[68] and, in principle, it could be applied over large distances in space.[66]

Assuming available laser technology, and considering the divergence of the interferometric signals, the range for satellite-to-satellite communications has been estimated to be approximately 2,000 km (1,200 mi).[69] These estimates are applicable to an array of satellites orbiting the Earth. For space vehicles or space stations, the range of communications is estimated to increase up to 10,000 km (6,200 mi).[69] This approach to secure space-to-space communications was selected by Laser Focus World as one of the top photonics developments of 2015.[70]

See alsoEdit

ReferencesEdit

  1. ^ Boroson, Don M. (2005), Optical Communications: A Compendium of Signal Formats, Receiver Architectures, Analysis Mathematics, and Performance Characteristics, archived from the original on 3 March 2016, retrieved 8 January 2013
  2. ^ "LLCD: 2013-2014". National Aeronautics and Space Agency. 15 June 2018. Retrieved 27 August 2022.
  3. ^ Steen Eiler Jørgensen (27 October 2003). "Optisk kommunikation i deep space – Et feasibilitystudie i forbindelse med Bering-missionen" (PDF). Dansk Rumforskningsinstitut. Retrieved 28 June 2011. (Danish) Optical Communications in Deep Space, University of Copenhagen
  4. ^ "Argon Laser as Seen from the Moon".
  5. ^ Berger, Brian (15 November 2004). "NASA To Test Laser Communications With Mars Spacecraft". Space.com. Retrieved 24 February 2018.
  6. ^ Araki, Kenichi; Arimoto, Yoshinori; Shikatani, Motokazu; Toyoda, Masahiro; Toyoshima, Morio; Takahashi, Tetsuo; Kanda, Seiji; Shiratama, Koichi (1996). "Performance evaluation of laser communication equipment onboard the ETS-VI satellite". In Mecherle, G. Stephen (ed.). Free-Space Laser Communication Technologies VIII. Vol. 2699. SPIE. p. 52. doi:10.1117/12.238434.
  7. ^ "A world first: Data transmission between European satellites using laser light". 22 November 2001. Retrieved 5 September 2015.
  8. ^ "Optical Communications in Space". ESA. August 1997.
  9. ^ "Another world first for ARTEMIS: a laser link with an aircraft". ESA. 19 December 2006. Archived from the original on 3 September 2009.
  10. ^ "Space probe breaks laser record: A spacecraft has sent a laser signal to Earth from 24 million km away in interplanetary space". BBC News. 6 January 2006. Retrieved 28 June 2011.
  11. ^ Toyoshima, Morio; Takenaka, Hideki; Shoji, Yozo; Takayama, Yoshihisa; Koyama, Yoshisada; Kunimori, Hiroo (May 2012). "Acta Astronautica "Results of Kirari optical communication demonstration experiments with NICT optical ground station (KODEN) aiming for future classical and quantum communications in space"". Acta Astronautica. 74: 40–49. doi:10.1016/j.actaastro.2011.12.020. Retrieved 18 February 2020.
  12. ^ Laser Communication Terminals: An Overview Archived 2016-09-11 at the Wayback Machine
  13. ^ Tesat-Spacecom Website
  14. ^ TerraSAR-X NFIRE test
  15. ^ Peckham, Matt (21 January 2013). "NASA Beams Mona Lisa Image Into Space". Time. Retrieved 22 January 2013.
  16. ^ "NASA launches robotic explorer to moon from Va.; trouble develops early in much-viewed flight". Toledo Blade. Associated Press. 7 September 2013. Archived from the original on 15 May 2016. Retrieved 15 May 2016.
  17. ^ a b Messier, Doug (23 October 2013). "NASA Laser System Sets Record with Data Transmissions From Moon". Parabolic Arc. Retrieved 23 October 2013.
  18. ^ Belz, Lothar (19 December 2013). "Optical data link successfully demonstrated between fighter plane and ground station". Archived from the original on 30 December 2013.
  19. ^ Extreme Test for the ViaLight Laser Communication Terminal MLT-20 – Optical Downlink from a Jet Aircraft at 800 km/h, December 2013
  20. ^ "Laserkommunikation zwischen Jet und Bodenstation".
  21. ^ "First image download over new gigabit laser connection in space". Archived from the original on 15 April 2015. Retrieved 3 December 2014.
  22. ^ "Laser link offers high-speed delivery". ESA. 28 November 2014. Retrieved 5 December 2014.
  23. ^ "Start of service for_Europe's Space Data Highway". ESA. 23 November 2016. Retrieved 11 April 2019.
  24. ^ "European Space Data Highway forges 20000 successful laser links". ESA. 2 April 2019. Retrieved 5 April 2019.
  25. ^ Landau, Elizabeth (9 December 2014). "OPALS: Light Beams Let Data Rates Soar". Jet Propulsion Laboratory. NASA. Retrieved 18 December 2014.   This article incorporates text from this source, which is in the public domain.
  26. ^ L. Smith, Stephanie; Buck, Joshua; Anderson, Susan (21 April 2014). "JPL Cargo Launched to Space Station". Jet Propulsion Laboratory. NASA. Retrieved 22 April 2014.   This article incorporates text from this source, which is in the public domain.
  27. ^ "Acta Astronautica "LEO-to-ground optical communications using SOTA (Small Optical TrAnsponder) – Payload verification results and experiments on space quantum communications"". Acta Astronautica. Retrieved 18 February 2020.
  28. ^ Takenaka, Hideki; Carrasco-Casado, Alberto; Fujiwara, Mikio; et al. (2017). "Satellite-to-ground quantum-limited communication using a 50-kg-class microsatellite". Nature Photonics. 11 (8): 502–508. arXiv:1707.08154. doi:10.1038/nphoton.2017.107. ISSN 1749-4885. S2CID 118935026.
  29. ^ a b Metz, Cade (24 February 2016). "Google Laser-Beams the Film Real Genius 60 Miles Between Balloons". Wired. Retrieved 24 February 2018.
  30. ^ a b Price, Rob (29 June 2018). "Facebook tested plane-mounted lasers that fire super high-speed internet over California — here are the photos". Business Insider. Archived from the original on 29 June 2018. Retrieved 21 July 2018.
  31. ^ "Small Optical Link for International Space Station (SOLISS) Succeeds in Bidirectional Laser Communication Between Space and Ground Station". JAXA. 23 April 2020. Retrieved 7 August 2020.
  32. ^ "「データ中継衛星」搭載のH2Aロケット43号機打ち上げ成功". NHK. 29 November 2020. Retrieved 29 November 2020.
  33. ^ "光衛星間通信システム（LUCAS". JAXA. 30 October 2020. Retrieved 29 November 2020.
  34. ^ "DoD space agency to launch laser communications experiments on SpaceX rideshare". SpaceNews. 2 June 2021.
  35. ^ a b Greicius, Tony (14 September 2017). "Psyche Overview". Nasa. Retrieved 18 September 2017.   This article incorporates text from this source, which is in the public domain.
  36. ^ a b Deep Space Communications via Faraway Photons NASA, 18 October 2017   This article incorporates text from this source, which is in the public domain.
  37. ^ Toyoshima, Morio; Fuse, Tetsuharu; Carrasco-Casado, Alberto; Kolev, Dimitar R.; Takenaka, Hideki; Munemasa, Yasushi; Suzuki, Kenji; Koyama, Yoshisada; Kubo-Oka, Toshihiro; Kunimori, Hiroo (2017). "Research and development on a hybrid high throughput satellite with an optical feeder link — Study of a link budget analysis". 2017 IEEE International Conference on Space Optical Systems and Applications (ICSOS). pp. 267–271. doi:10.1109/ICSOS.2017.8357424. ISBN 978-1-5090-6511-0. S2CID 13714770.
  38. ^ Carrasco-Casado, Alberto; Do, Phong Xuan; Kolev, Dimitar; Hosonuma, Takayuki; Shiratama, Koichi; Kunimori, Hiroo; Trinh, Phuc V.; Abe, Yuma; Nakasuka, Shinichi; Toyoshima, Morio (2020). "Intersatellite-Link Demonstration Mission between CubeSOTA (LEO CubeSat) and ETS9-HICALI (GEO Satellite)". 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS). pp. 1–5. arXiv:2002.02791. Bibcode:2020arXiv200202791C. doi:10.1109/ICSOS45490.2019.8978975. ISBN 978-1-7281-0500-0. S2CID 211059224.
  39. ^ J. Horwath; M. Knapek; B. Epple; M. Brechtelsbauer (21 July 2006). "Broadband Backhaul Communication for Stratospheric Platforms: The Stratospheric Optical Payload Experiment (STROPEX)" (PDF). SPIE.
  40. ^ "Inside The World's First Space-Based Commercial Laser-Relay Service". Aviation Week. Archived from the original on 15 March 2015. Retrieved 24 February 2018.
  41. ^ "HALO Global Network by Laser Light Communications". Retrieved 13 November 2018.
  42. ^ "Ball Corp Prime Contractor for Laser Light's Satellite Fleet - Analyst Blog". nasdaq.com. 11 September 2014. Retrieved 24 February 2018.
  43. ^ "Mynaric, SpaceLink Partner to Accelerate Satellite Laser Terminal Technology - Via Satellite -". Via Satellite. 12 May 2021. Retrieved 2 June 2021.
  44. ^ "WarpHub InterSat" (PDF). Retrieved 3 March 2021.
  45. ^ Khalid, Asma (19 September 2017). "With US$200 Million, MIT's The Engine Makes Its First Investments In 'Tough Tech'". wbur.org. Retrieved 24 February 2018.
  46. ^ Harris, David L. (12 March 2015). "This Boston startup is building a faster way to send data from satellites — using lasers". Boston Business Journal. Retrieved 24 February 2018.
  47. ^ SPIE Europe. "Miniature satellites to transmit optical data from space". optics.org. Retrieved 24 February 2018.
  48. ^ "Cloud Constellation Selects Mynaric Laser OISL Terminals for its SpaceBelt Satellites - Via Satellite -". Via Satellite. 20 May 2021.
  49. ^ a b "US Military Places a Bet on LEO for Space Security". interactive.satellitetoday.com.
  50. ^ "To boost its military space business, Lockheed Martin turns to commercial players". SpaceNews. 23 November 2020.
  51. ^ "DoD to test laser communications terminals in low Earth orbit". SpaceNews. 8 June 2020.
  52. ^ SPIE Europe. "Thales signs deal on optically connected satellites". optics.org. Retrieved 24 February 2018.
  53. ^ "LeoSat, absent investors, shuts down". SpaceNews. 13 November 2019.
  54. ^ "OneWeb 'plans optical links' for next generation of satellit". www.capacitymedia.com. March 2021.
  55. ^ https://www.arcep.fr/uploads/tx_gspublication/contributions-consult-starlink_juin2022.zip[bare URL]
  56. ^ "Latest Starlink Satellites Equipped with Laser Communications, Musk Confirms - Via Satellite -". Via Satellite. 25 January 2021.
  57. ^ Grush, Loren (3 September 2020). "With latest Starlink launch, SpaceX touts 100 Mbps download speeds and 'space lasers'". The Verge. Retrieved 3 September 2020.
  58. ^ Newton, Casey (21 July 2016). "Inside the test flight of Facebook's first internet drone". The Verge. Retrieved 24 February 2018.
  59. ^ "Big Gains On Horizon For Laser Communications Suppliers". Aviation Week. 11 March 2015. Retrieved 24 February 2018.(subscription required)
  60. ^ Russell, Kendall (17 April 2018). "Honeywell, Ball to Develop Optical Communication Links - Via Satellite -". Satellite Today. Retrieved 21 April 2018.
  61. ^ "RBC Signals and Ecuadorian Civilian Space Agency (EXA) Announce Collaboration For Optical Communication System -". RBC Signals. 4 October 2018. Retrieved 28 February 2021.
  62. ^ "LASER COMMUNICATIONS FOR CUBESATS: A 50 MBPS LASER/RADIO HYBRID TRANSCEIVER IN A PC-104 FORM FACTOR CARD -". Research Gate. 14 October 2019. Retrieved 28 February 2021.
  63. ^ Henry, Caleb (18 May 2016). "DARPA Awards Optical Satellite Terminal Contract to LGS Innovations". Satellite Today. Retrieved 24 February 2018.
  64. ^ "Sony to launch space business". Nikkei Asian Review. 15 April 2018. Retrieved 21 April 2018.
  65. ^ Karekar, Rupali (22 March 2017). "Space buffs make light work of data transfer". The Straits Times. Retrieved 24 February 2018.
  66. ^ a b c F. J. Duarte (May 2002). "Secure interferometric communications in free space". Optics Communications. 205 (4): 313–319. Bibcode:2002OptCo.205..313D. doi:10.1016/S0030-4018(02)01384-6.
  67. ^ Duarte, F. J. (January 2005). "Secure interferometric communications in free space: enhanced sensitivity for propagation in the metre range". Journal of Optics A: Pure and Applied Optics. 7 (1): 73–75. Bibcode:2005JOptA...7...73D. doi:10.1088/1464-4258/7/1/011.
  68. ^ F. J. Duarte, T. S. Taylor, A. M. Black, W. E. Davenport, and P. G. Varmette, N-slit interferometer for secure free-space optical communications: 527 m intra interferometric path length, J. Opt 13, 035710 (2011)
  69. ^ a b F. J. Duarte and T. S. Taylor, Quantum entanglement physics secures space-to-space interferometric communications, Laser Focus World 51(4), 54-58 (2015)
  70. ^ J. Wallace, Technology Review: Top 20 technology picks for 2015 showcase wide scope of photonics advances, Laser Focus World 51(12), 20-30 (2015)

Further readingEdit

  • David G. Aviv (2006): Laser Space Communications, ARTECH HOUSE ISBN 1-59693-028-4

By using this platform, you agree to the Terms of Use ©2020 Knowpia