GB2267006A - Optical link for a satellite - Google Patents

Optical link for a satellite Download PDF

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Publication number
GB2267006A
GB2267006A GB9309812A GB9309812A GB2267006A GB 2267006 A GB2267006 A GB 2267006A GB 9309812 A GB9309812 A GB 9309812A GB 9309812 A GB9309812 A GB 9309812A GB 2267006 A GB2267006 A GB 2267006A
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GB
United Kingdom
Prior art keywords
amplifying
wave
mobile
reception
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9309812A
Other versions
GB2267006B (en
GB9309812D0 (en
Inventor
Jose Chesnoy
Jean-Pierre Blondel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Espace Industries SA
Original Assignee
Alcatel Espace Industries SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcatel Espace Industries SA filed Critical Alcatel Espace Industries SA
Publication of GB9309812D0 publication Critical patent/GB9309812D0/en
Publication of GB2267006A publication Critical patent/GB2267006A/en
Application granted granted Critical
Publication of GB2267006B publication Critical patent/GB2267006B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/118—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum specially adapted for satellite communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/29—Repeaters
    • H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
    • H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Communication System (AREA)

Abstract

The apparatus includes an amplifying fiber (10) for guiding and amplifying a light wave (W1) which carries data to be transmitted, and which is then directed at a party (54) involved in a call by means of a steerable antenna (6). The invention applies, in particular, to data transmission between two satellites, and enables a longer-wavelength broader (and hence more easily steered) beam of higher power to be transmitted. The amplifying fiber may be in the transmitter, the receiver or both. <IMAGE>

Description

OPTICAL LINK APPARATUS FOR A MOBILE, IN PARTICULAR FOR AN EARTH SATELLITE The present invention relates to setting up links enabling data to be transmitted between two parties involved in a call, at least one of the parties being mobile. More precisely, the invention relates to the case in which such links are optical, and it advantageously applies when a mobile to be connected is orbiting outside the Earth's atmosphere. Such is the case, in particular, for artificial satellites orbiting the Earth.
It is known that, in telecommunications systems, optical links between such satellites offer several advantages: confidentiality, safety, possibility of high data rates.
A particularly difficult problem to solve in such links, is that of aiming the antenna of each satellite towards the other satellite, i.e. steering it with the required accuracy. This difficulty means that the apparatus has to be very complex, thereby making it heavier and less reliable.
It is known that in order to reduce the complexity of the apparatus, a link wavelength in the vicinity of 850 nm can be chosen, thereby enabling semiconductor diodes made of GaAs (particularly powerful) to be used for transmission purposes, and silicon detector diodes (enabling particularly sensitive heterodyne or direct detection) to be used for reception purposes.
The present invention has the following objects, in particular: facilitating aiming of the antennas on two satellites between which an optical link is to be set up; improving, in simple manner, the quality of such a link with respect to the data-rate and the error-rate thereof; lightening the apparatus taken on board satellites to set up the link; increasing the range of such a link; and/or increasing the reliability of such apparatus.
To achieve these objects, the invention provides, in particular, optical link apparatus including an amplifying fiber for guiding and amplifying a light wave carrying data to be transmitted.
It can be noted that, prior to the present invention, the use of an amplifying fiber in such an application did not seem desirable, because it requires using a much longer link wavelength, which, in order to retain the gain of an antenna constituted by a substantially parabolic reflector, means that the diameter of the reflector must be increased.
However, with the present invention, it is apparent that a moderate decrease in the antenna gain was both acceptable because of the gain contributed by the amplifying fiber, and also advantageous because the angular accuracy required for aiming is decreased.
In addition, an increase in the link wavelength appeared to be a drawback because it meant that particularly powerful transmitter diodes could not be used for transmission, and that particularly sensitive detector diodes could not be used for detection, since such diodes can only work usefully at the link wavelengths used by known apparatus. But, with the present invention, it is also apparent that the gain contributed by an amplifying fiber makes it possible to compensate fully for the losses in power and in sensitivity resulting from the need to use different transmitter diodes and different detector diodes.
An embodiment of the present invention is described below with reference to the accompanying diagrammatic figure, it being understood that the components and dispositions are mentioned and shown only by way of nonlimiting example.
The figure is a view of two artificial satellites orbiting the Earth with a link set up between them by means of apparatus of the invention. The two satellites constitute a transmitter mobile and a receiver mobile, each of the mobiles constituting a party involved in a call with the other.
Transmission apparatus of the invention includes the following components whose functions mentioned are known: a transmitter system 2, 10, 12, 14, 16 carried by the transmitter mobile 4 for producing a primary transmission wave W2 carrying data to be transmitted from the mobile to a party 54 involved in a call with the mobile; a steerable transmission antenna 6 carried by the mobile for transforming the primary transmission wave into a steerable parallel secondary transmission beam W3; and aiming means 8 for steering the antenna so as to direct the secondary transmission beam W3 at said party.
A control circuit 18 receives the data to be transmitted which is supplied to it by a data-processing system 20.
The control circuit controls the laser transmitter system accordingly, to make the primary transmission wave W2 carry the data.
The control circuit also controls the aiming means 8.
In accordance with the present invention, the laser transmitter system includes: a semiconductor transmitter diode 2 constituting a laser oscillator and emitting a light wave constituting an initial wave W1 and having a link wavelength that is greater than 1,000 nm; an amplifying fiber 10 constituted by an optical fiber doped with an amplifying material suitable for amplifying light having said link wavelength when the material is excited by pump light 11 having a pumping wavelength that is shorter than the link wavelength and that is specific to the doping material; a pump source 12 for producing the pump light; and an optical coupler 14 for making the initial wave and the pump light propagate together inside the amplifying fiber, such that amplifying the initial wave W1 produces said primary transmission wave W2.
The amplifying fiber 10 receives the initial wave directly. It receives the pump light via a coupling fiber 16 and via the coupler 14.
Reception apparatus of the invention, involved in a call with the transmitter mobile 4, includes the following components whose functions mentioned are known: a steerable reception antenna 56 carried by a receiver mobile 54 for selectively receiving a light-type primary reception beam W3 arriving at the mobile along a steerable reception axis, and for transforming the primary reception beam into a light wave constituting a secondary reception wave W4; aiming means 58 for steering the antenna so as to direct the reception axis at a party 4 involved in a call with the mobile; and a semiconductor detector system 60, 61, 62, 64, 52 for receiving the secondary reception wave W4 and responding by supplying the data to be transmitted as conveyed to the receiver mobile by the primary reception beam W3.
A control circuit 68 receives the data to be transmitted, and supplies it to a data-processing system 70.
The control circuit also controls the aiming means 58.
In accordance with the present invention, the detector system includes: an amplifying fiber 60 constituted by an optical fiber doped with an amplifying material suitable for amplifying light having a link wavelength that is greater than 1,000 nm when the material is excited by pump light 61 having a pumping wavelength that is shorter than the link wavelength and that is specific to the doping material; a pump source 62 for producing the pump light; an optical coupler 64 for making the secondary reception wave and the pump light propagate together inside the amplifying fiber, such that amplifying the secondary reception wave produces an amplified reception wave; and a semiconductor detector diode 52 receiving the amplified reception wave and responding by supplying said data.
The amplifying fiber 60 receives the secondary reception wave W4 directly.
It receives the pump light via a coupling fiber 66 and via the coupler 64.
Preferably, and as known per se for making amplifying fibers, said amplifying material is erbium or praseodymium, said link wavelength being approximately 1,550 nm or approximately 1,310 nm, respectively. The transmitter diode 2 and the detector diode 52 are made of indium phosphide InP, for example.
The couplers are multiplexers of the melt-drawn type or of the interference-filter type. The pump sources are laser diodes and transmit at about 1,480 nm, 980 nm (erbium), or 1,020 nm (praseodymium) depending on the rare earth used to constitute the amplifying material.
By way of example, amplifying on transmission and on reception makes it possible to achieve loss corresponding to the geometrical limit of links between two geostationary satellites for a data rate of 150 Mbits. Assuming an aiming error of 3 dB, reception antenna efficiency of 3 dB and transmission antenna efficiency of 1 dB, a range of 60,000 km is reached with 0.1 nm optical filtering on reception, and a detector diode constituted by an avalanche photodiode (APD). This case corresponds to relatively average performance levels, in particular for the gain of the reception amplifier (about 27 dB) and the output power of the transmission amplifier (13 dBm). Under the same conditions, more severe optical filtering (0.01 nm) enables a range of 80,000 km to be reached. By way of comparison, removing the amplification, under the same conditions, reduces the range to a value of 5,000 km.

Claims (1)

1/ Optical link apparatus for a mobile, in particular for an Earth satellite, said apparatus being characterized by the fact that it includes an amplifying fiber (10) for guiding and amplifying a light wave (W1) carrying data to be transmitted.
2/ Apparatus according to claim 1, including a steerable transmission antenna (6), said light wave (W1) passing through said antenna.
3/ Optical link apparatus according to claim 2 for a mobile, in particular for an Earth satellite, the apparatus including: a transmitter system (2, 10, 12, 14, 16) carried by a transmitter mobile (4) for producing a primary transmission wave (W2) carrying data to be transmitted from the mobile to a party (54) involved in a call with the mobile; a steerable transmission antenna (6) carried by the mobile for transforming the primary transmission wave into a steerable parallel secondary transmission beam (W3); and aiming means (8) for steering the antenna so as to direct the secondary transmission beam (W3) at said party; the apparatus being characterized by the fact that said transmitter system includes: a semiconductor transmitter (2) emitting a light wave constituting an initial wave (W1) and having a link wavelength that is greater than 1,000 nm; an amplifying fiber (10) constituted by an optical fiber doped with an amplifying material suitable for amplifying light having said link wavelength when the material is excited by pump light (11) having a pumping wavelength that is shorter than the link wavelength; a pump source (12) for producing the pump light; and an optical coupler (14) for making the initial wave and the pump light propagate together inside the amplifying fiber, such that amplifying the initial wave (W1) produces said primary transmission wave (W2).
4/ Optical link apparatus according to claim 2 for a mobile, in particular for an Earth satellite, the apparatus including: a steerable reception antenna (56) carried by a receiver mobile (54) for selectively receiving a light-type primary reception beam (W3) arriving at the mobile along a steerable reception axis, and for transforming the primary reception beam into a light wave constituting a secondary reception wave (W4); aiming means (58) for steering the antenna so as to direct the reception axis at a party (4) involved in a call with the mobile; and a semiconductor detector system (60, 61, 62, 64, 52) for receiving the secondary reception wave (W4) and responding by supplying data as conveyed to the receiver mobile by the primary reception beam (W3); the apparatus being characterized by the fact that said detector system includes: an amplifying fiber (60) constituted by an optical fiber doped with an amplifying material suitable for amplifying light having a link wavelength that is greater than 1,000 nm when the material is excited by pump light (61) having a pumping wavelength that is shorter than the link wavelength; a pump source (62) for producing the pump light; an optical coupler (64) for making the secondary reception wave and the pump light propagate together inside the amplifying fiber, such that amplifying the secondary reception wave produces an amplified reception wave; and a semiconductor detector diode (52) receiving the amplified reception wave and responding by supplying said data.
5/ Apparatus according to any preceding claim, characterized by the fact that said amplifying material is erbium or praseodymium, said link wavelength being approximately 1,550 nm or approximately 1,310 nm, respectively.
6/ Apparatus according to claim 3, characterized by the fact that said semiconductor transmitter is a transmitter diode (2) is made of indium phosphide InP.
7/ Apparatus according to claim 4, characterized by the fact that said semiconductor detector is a detector diode (52) is made of indium phosphide InP.
8/ Optical link apparatus for a mobile substantially as hereinbefore described with reference to the accompaying figure.
Amendments to the claims have been filed as follows 1. A free space optical link apparatus for a mobile, in particular for an earth satellite, said apparatus being characterised by the fact that it includes an amplifying fiber for guiding and amplifying a light wave carrying data to be transmitted.
GB9309812A 1992-05-12 1993-05-12 Optical link apparatus for a mobile, in a particular for an earth satellite Expired - Fee Related GB2267006B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR9205751A FR2691310B1 (en) 1992-05-12 1992-05-12 Optical link device for mobile, in particular for earth satellite.

Publications (3)

Publication Number Publication Date
GB9309812D0 GB9309812D0 (en) 1993-06-23
GB2267006A true GB2267006A (en) 1993-11-17
GB2267006B GB2267006B (en) 1995-08-30

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9309812A Expired - Fee Related GB2267006B (en) 1992-05-12 1993-05-12 Optical link apparatus for a mobile, in a particular for an earth satellite

Country Status (2)

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FR (1) FR2691310B1 (en)
GB (1) GB2267006B (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0771087A2 (en) * 1995-10-26 1997-05-02 Trw Inc. Photonic interconnect and photonic processing for communication and data handling satellites
GB2320151A (en) * 1996-11-12 1998-06-10 L F D Limited Covert infra-red communications system
EP0863628A1 (en) * 1997-03-07 1998-09-09 Oerlikon Contraves Ag Method and means to operate a laser emitter system for optical free space communication
EP0878880A1 (en) * 1997-06-25 1998-11-18 Oerlikon Contraves Ag Method and apparatusfor space based operation of optical waveguide amplifiers
US5870216A (en) * 1995-10-26 1999-02-09 Trw Inc. Splitterless optical broadcast switch
EP0952690A2 (en) * 1998-05-06 1999-10-27 Oerlikon Contraves Ag System for determining of alignement data in optical communication links

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2950763B1 (en) * 2009-09-30 2012-05-11 Astrium Sas SYSTEM AND METHOD FOR OPTICAL LINK COMMUNICATION AND ASSOCIATED RELAY TERMINAL

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2151869A (en) * 1983-12-16 1985-07-24 Standard Telephones Cables Ltd Optical amplifiers
EP0231016A2 (en) * 1986-01-28 1987-08-05 AT&T Corp. Fiber soliton optical telecommunication system
WO1987004881A1 (en) * 1986-01-31 1987-08-13 Advanced Lasers Ltd. Fibre communication laser system
EP0499388A2 (en) * 1991-02-15 1992-08-19 Hughes Aircraft Company Bidirectional optical fibre communication link incorporating an amplifier

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3674362D1 (en) * 1985-06-19 1990-10-25 British Telecomm OPTICAL TRANSMISSION SYSTEM.
GB8801008D0 (en) * 1988-01-18 1988-02-17 British Aerospace Acquisition system for multiple access optical communication system
US5062150A (en) * 1989-01-23 1991-10-29 Massachusetts Institute Of Technology Fiber-based free-space optical system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2151869A (en) * 1983-12-16 1985-07-24 Standard Telephones Cables Ltd Optical amplifiers
EP0231016A2 (en) * 1986-01-28 1987-08-05 AT&T Corp. Fiber soliton optical telecommunication system
WO1987004881A1 (en) * 1986-01-31 1987-08-13 Advanced Lasers Ltd. Fibre communication laser system
EP0499388A2 (en) * 1991-02-15 1992-08-19 Hughes Aircraft Company Bidirectional optical fibre communication link incorporating an amplifier

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WPI Accession No.88-155631 & DE 3638455 A *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0771087A2 (en) * 1995-10-26 1997-05-02 Trw Inc. Photonic interconnect and photonic processing for communication and data handling satellites
US5661582A (en) * 1995-10-26 1997-08-26 Trw Inc. Photonic interconnect and photonic processing for communications and data handling satellites
US5870216A (en) * 1995-10-26 1999-02-09 Trw Inc. Splitterless optical broadcast switch
EP0771087A3 (en) * 1995-10-26 2000-10-18 Trw Inc. Photonic interconnect and photonic processing for communication and data handling satellites
GB2320151A (en) * 1996-11-12 1998-06-10 L F D Limited Covert infra-red communications system
EP0863628A1 (en) * 1997-03-07 1998-09-09 Oerlikon Contraves Ag Method and means to operate a laser emitter system for optical free space communication
US6301037B1 (en) 1997-03-07 2001-10-09 Contraves Space Ag Laser transmitting system for use in optical space communication systems
EP0878880A1 (en) * 1997-06-25 1998-11-18 Oerlikon Contraves Ag Method and apparatusfor space based operation of optical waveguide amplifiers
US6018602A (en) * 1997-06-25 2000-01-25 Oerlikon Contraves Ag Method and arrangement for the space-based operation of quantum-optical amplifiers embodied as optical waveguides
EP0952690A2 (en) * 1998-05-06 1999-10-27 Oerlikon Contraves Ag System for determining of alignement data in optical communication links
EP0952690A3 (en) * 1998-05-06 2000-03-01 Oerlikon Contraves Ag System for determining of alignement data in optical communication links

Also Published As

Publication number Publication date
FR2691310A1 (en) 1993-11-19
GB2267006B (en) 1995-08-30
GB9309812D0 (en) 1993-06-23
FR2691310B1 (en) 1995-05-12

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20010512