CA2093724A1 - Optical communication system with a power limiter for high-energy pulses - Google Patents
Optical communication system with a power limiter for high-energy pulsesInfo
- Publication number
- CA2093724A1 CA2093724A1 CA002093724A CA2093724A CA2093724A1 CA 2093724 A1 CA2093724 A1 CA 2093724A1 CA 002093724 A CA002093724 A CA 002093724A CA 2093724 A CA2093724 A CA 2093724A CA 2093724 A1 CA2093724 A1 CA 2093724A1
- Authority
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- Canada
- Prior art keywords
- optical
- communication system
- power
- power limiter
- fiber
- 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.)
- Abandoned
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 54
- 238000004891 communication Methods 0.000 title claims abstract description 15
- 230000006854 communication Effects 0.000 title claims abstract description 15
- 238000010521 absorption reaction Methods 0.000 claims abstract description 8
- 239000011358 absorbing material Substances 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 4
- 229910004613 CdTe Inorganic materials 0.000 claims description 2
- 229910052779 Neodymium Inorganic materials 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 claims description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 2
- 239000004065 semiconductor Substances 0.000 claims 3
- 229910052775 Thulium Inorganic materials 0.000 claims 1
- 229910052793 cadmium Inorganic materials 0.000 claims 1
- 229940044194 cadmium Drugs 0.000 claims 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims 1
- 239000000835 fiber Substances 0.000 abstract description 2
- 230000001902 propagating effect Effects 0.000 abstract 1
- 150000002500 ions Chemical class 0.000 description 5
- 229910052691 Erbium Inorganic materials 0.000 description 2
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 2
- 230000005281 excited state Effects 0.000 description 2
- 230000002269 spontaneous effect Effects 0.000 description 2
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 description 1
- XUKUURHRXDUEBC-KAYWLYCHSA-N Atorvastatin Chemical compound C=1C=CC=CC=1C1=C(C=2C=CC(F)=CC=2)N(CC[C@@H](O)C[C@@H](O)CC(O)=O)C(C(C)C)=C1C(=O)NC1=CC=CC=C1 XUKUURHRXDUEBC-KAYWLYCHSA-N 0.000 description 1
- VVNCNSJFMMFHPL-VKHMYHEASA-N D-penicillamine Chemical compound CC(C)(S)[C@@H](N)C(O)=O VVNCNSJFMMFHPL-VKHMYHEASA-N 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 229940075911 depen Drugs 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005283 ground state Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/3526—Non-linear optics using two-photon emission or absorption processes
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/3523—Non-linear absorption changing by light, e.g. bleaching
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
- Optical Communication System (AREA)
Abstract
Abstract Optical Communication System with a Power Limiter for High-Energy Pulses In optical communication systems with optical with optical amplifiers, there is the danger of system components being damaged in the event of a break in the fiber-optic link, e.g., due to fiber breakage.
This can be explained by the emission of high-energy pulses.
To prevent such pulses from propagating in the fiber-optic link, a power limiter which, by introducing attenuation, limits the optical power of the pulses to a value not dangerous to the system components is inserted in the fiber-optic link. The attentuation is provided by two-photon absorption.
(Fig.1)
This can be explained by the emission of high-energy pulses.
To prevent such pulses from propagating in the fiber-optic link, a power limiter which, by introducing attenuation, limits the optical power of the pulses to a value not dangerous to the system components is inserted in the fiber-optic link. The attentuation is provided by two-photon absorption.
(Fig.1)
Description
372~
Optical Communicatior~ Syst~m w;th a Power lirr,itcr for High-~nergy Pulses The pres~rt inv~tion re!ates to an opticaL communica-tion system as sc~t forth in the preamble of claim 1.
Such system~ are known, e.g., frc,m a. Wedding et al, "10 Gbit!s to 260000 Sub,cribers Using Optical Amplifier D;str;bu.ion Net,~ork", Contribution for ICC/Supe~comm '9~, Opti~a~ Commurlicatic)ns 300 Level Session, "Impact o~ Opt;cal Am~liFiers or, ~etwork Architectures".
In such ofticdl comrnunication systems, ;n which the trans-mission llnk is ~ fiber-optic link, optical amplifiers serve to a.~plify optical iignals transmitted through the Optical wave~3uides.
The opti~a' amplifier chosen ;n the embodiment described below ;5 a fiber-optic amp'ifier. A fiber-opt;c ampl;-fier -is s~o~n in EP O 457 34~ A2, for examPle.
In such fiber-opi~ic amplifiers, erb;urn ions with which a sect;on .~f optical waveguide is doped are raised from a ground s tate to an exc ited state by pump light em;tted b~ a pumf) sourcc~ and from the excited state, the ions drop back, throlgh e;ther spontaneous or stimu-lated emissiorl, to th~ ground state. The st;m~lated emis-sion is e~ited oy the optical signal to be amplified, ~3~
whirh tra~els thtowgh the section of doped optical wave-gu;rle. Th ~pont~neou~; emiss;on is also amplif;ed ;n the doped ~;ection o~ opt-ical ~aveguide; this amplified spontaneou ~mi~ion (A5~) causes the noise internal to a fiber-opti(: amplifie~
In the ab~e-menlionec' syste~, there is the danger that ;n the ev~,;t of a break -in the fiber-optic l;nk, e.g., du~ tc fit,er br~ak3~e or to separat;on of a f;be~-optic con-,e~t~r, s~stem components, such as pho~od;odes, will be da!naged.
This carl l~? eYplained as foLlo~s:
As a re~u~ of the break ;n the fiber-optic link, the powe~ input to the op~ical amplifier decrea~es to zero. Since the pumping process ;s independent of the power input, er,ergy will be pumped ;nto the dooed oDt;cal-waveouide section even if the power ;nput has dropped, so th~t com-plete populc,t;on ;nversion w;ll occur. When light which re~ul~s from sp-)ntaneous emiss;on and is reflect-ed at thc interf~ce o~ the break in the fiber-opt;c l1n~ i)asse~ ~hro~lgh the section of doped optical wave~uide,whose active l~ser medium, e.g., erb;um ;ons, ;s ;n the -invert~d stat~, the stored enerc~y will be suddenly re~eas~d. High energy pulses w;ll be emitted which are a danyer to s~stem components.
These g;ant pul~es oropagate both in and opposite to the direct;ol, Df signal tlow. In the case of erb;um-doped fiber-optic ampl;fiers, the wavelength of the gi~nt pulses is ~n the range between 15Z0 nm and 1570 nm.
_ 3 _ ;~372~
Such fit)el~-()ptic a~plifi~rs are not only used in optical communica~ion ~stems~ ine~ are also employed in assem-blies ~1 Iro~isional setu~)s which are provided for the start-up ~J~ s~ch s~stems to permit measurements, tests, or step~ st~p installation. Reflecting surfaces may be intention,.lly or u~inten~ionally inse~ted in these set-ups and mil~ tnen cause back reflection of the light amplificd ~, the amplifier. Such reflecting surfaces are formei~ ln particular by a connect;ng element or a cut-off end of t1n optical waveguide.
An optica~ ampli~ier witl, a section of doped optical waveeu;de mây h.lve such a high gain that, if subjected, for exam~.!e, to unintentional back reflection, it will turn into 3 Lase~ GSCi llator due to a phenomenon called "Q-switchlr;y". ~hiC, too~ ~uses hi~h-energy pulses wh;ch nldy ~anlaQe system components. A known solution to the probl-r~ of how to avoid such daraage consists of insertin3 or,e or more op~ical isolators in the optical transmissicn path. These isolators can transmit l;ght ;n only one direction, whereby back reflect;ons are prevent-ed. Thus, t~,e optical amplifier can be prevented from operatin~ as a laser oscil~ator. OPtical isolators are the p~ssi e components with the highest complexity and, thus, the ri~hest price in a system or an optical ampli-fier with GptiCa l waveguide.
It is the o~ject of the in~ention to prov;de an optical communic~;ior~ ~yst~m co~r;sing optical amplifiers where-in th~ da~;~er of s,stem comPonents being damaged by high-energ~ ~u~ies i~ a~oided.
~37~l~
Th;s Oi~ je~:L i.~ a~.tainr:(i as set forth i.n claim 1 Further advantar~r~ous as~ct-s of ~he invention are defined in the subclainl~.
The in~rltion will no~. be explaineci in rnore detail with reference tc the accompar\ying d~w;ngs, in which:
fig 1 sr;J~S on~ r-mbodin~ent ~f an optical cr~mmuni-ca~;on system wi~h power ~imiters in accor-d;,~ce wi~:h the invent;on, Fig~ ~ lr:Oh'S th.~ attenuation of a power limiter as a f~n~;tion of the optical power input to the l,m;ter, c~nc-i Fig. 3 slow~ a riber-optic amplifier ~ith a oower lim;ter for ar, optical communication sys-t e m .
Fig. 1 sho~s an optical colnmunication system with an elec-trical-to-optical. ~ransduGer ~ at the transmitting end and one ol:.t.ical-!:o-ei~eç.trical transducer 3 at the re-ceiving er,l, which ar~ interconnected by an optical ~iaveguide 5. A colnmunicaiic)n system ~iith an electrical-tO-OptiCd trans~iucer at the transmitt;ng end and two or more ci~tribuied optir:al-to-electr;cal transducers at the receivir-g end ;s also ~ossible. This is of no con-sequence t or' tile invention The commuricatioa ~ystem of Fig 1 f~rther includes a fiber-opt c amPlifier 1 and two power l;miters 4.
- s- 2~372~
In this e~bodimeilt, as scer~ in the direction of propa-gat;on uf the oprical sigl13l, one power limiter 4 is ~ ted 1~ead ol the ~ibel-o~tic amplifier an~ one be-hind the .~mplifiar~ and they ~re implemented as sec-tions of (1 ped optic~l wa~egu;de. The two power (imiters are joine(~ to the fiber-~p~;c ampl;fier 1 and the optical wav~guide i ~-sin~ conventional splicin~ tethn;ques.
The power limitels ma~ also be imple~ented differentLy, e.g., as ~idtPle.s of abcjc,rb;ng mater;al which are in-serted i" the signal path at breaks in the Opticdl h'3Ve~Uide, e.g., in front of and behind the opt;c-" amplif;er, respectivelyA
Th;s abs"rbing matericll has p~operties wl1ich are de-srribed bll~w It is a~s~ po~3ible to place one power limiter behind the electricaL-t~-opt-ical transducer ~ and one in front of the op;ical-to-electr;cal transducer 3. This pro-tects thes~ system components from the effects of giant pul~es.
In pr3cti(al use, ~ibPr-,~pt;c amplifiers are also arransed n cascide. ]n that case, each of the links between the ;ndi~inual ~iber-optic amplifiers may con-tain one ~!ower limiter.
The power limiter has the following properties.
The po~er ~imit~r passes the optica~ signal with a normal ' : .' ~ 6 ~ 372~
optical ~ wl~r (a few !O nw~ and a wavelength of, e.g., ~ 15SO rm nearly unattenlJated. ~y contrast, it stron~ly atter\ucl'-e~; opti~al powers which correspond to that cf ti ~? gi3nt pulse ~watt ranye).
This is illustrated in ~i~. 2. The power ratio T = PtL~
Po is plo~te(, dS d fur;ction of the optical power input P~
to the ~ow~ iter. P(~) is the optical power output of a powe~ limiter of length L.
The depen{ierlce of the attenuation in the power li~iter is prefcrally nolline3r~ as shown in F;g. 2, so that high-power opt;cal ra~-Jiation w;ll be attenuated d;s-proportionately.
This ~tt~n~atior\ in the power lim;ter can be providedby ~;ght (attering. and/or absorption. The power li~;ter is preferai~ly ma~e of an absorbing material in which the absor~;tion i~ a two-~hoton process. The latter exhibits ;he part;cularly suitable nonlinear dependence of the op'ical input power. Th;s absorption is de-scribed, 10r exa~ple, in a book by r~R. Shen, "The Principle: ~f Nonlinear optics", John Wiley ~ Sons, pp. 202-2 ~), but nct in connection with a particular matarial r(ld not in connection ~;th optical waveguides.
The aforelknt;o~ rec~uiremc?ntS are fulfiLled, for examp~e, '~ a s~ction of doped optical waveguide made ~3~2~
of an abio!~,irlg n~aterial with two-photon absorpti~n.
Such an diJsort~ g mat~rial is neodymium~ Nd, or thu~i~;m, ''m, fo~ e~ample.
i~y an app!ot~riate cholce of the dop~nt and the doping concentra!;on in an optical waveguide, two-photon ab-sorl~tion is caused. The attenuation of the power limi~er i~, determ;ned by the length of the section of doped optical wavregui~.
~he fiber-o~tic amplifier ~iven as an example in ~i~. 3 tomprise. Lae fo'lo~ g elements, whose operation is ~nown from the alove-cited literature:
-- A st?ct i~ n of daped optical waveguide 33, wh;ch i5 doped wit~, e g , erbium i~ns and is capable of ~ccumulating CXCitatiQn energy suppl;ed by a pump source. 'le settion nf optical waveguide has two ends 35, 36.
- A pump ource 50~ which emits pump light.
- P~mp~lignt-couplilg means~ These means consist of a pump~ ht-:,oupling fiber 31 and a coupler 32.
Their fun(tion i~ to teed the putnp light into the section of t~opeti optical waveguide 33~
- A power limiter 4, shown here in the form of a section of ~ptiral wa~ey:Jide, contains a core with a semicorl-'uctiny absorbing material which is distri-buted ;n the core in the torm of microcrYstal-lites. Thij material is chosen to ha~e an absorption coefficien~ wh;ch increa!ieci ~ith increasing optical input pow~r, The absorption is a two-photon ~rocess.
-~- 20~372~
Preferabt~, the ab~or~irl~ material is a semiconduotor of the t~e ~ I, parttcularly cadmium telluride, CdTe.
The power li~iter is preferably connected in series with the ~ection of doped optical waveguide 33 by a splice ~4.
If the doping a~en~ is ionized erbium, Er , the ab-sorbing semieon~luc~or material will have a band glp correspundin~ to a wavelength between 750 nm and 1550 nm.
Gl~sses d(,ped with se~i~onductor m;crocrystallites were examined wi~h regard to ehe;r twû photon absorpt;on:
coefricients ~f 0.2 cm/GW were measured by F. Canto, E. M;esah et a~ (CLEO'88, Poster WM41) for the case where thY absor~t;on in the longitudinal direction is negl;gible (the energy of the photon is less than th~
band ga~). These results can be applied to optical wave-guides.
If, with such a coeff;c-ient (0.2 cm/GW), ;t ;s to be ensured that a ~,ower of 5W (10 MW/c~ ) is not exceeded in an opt ical communication system, and the loss to be ;nduced is 30 dtl, a power lim;ter implemented as an op-tical h~a~eguide ~Ust have a length of 30 m. The corres-ponding loss dt a power of 50 mW ;s then 0.3 dB.
Optical Communicatior~ Syst~m w;th a Power lirr,itcr for High-~nergy Pulses The pres~rt inv~tion re!ates to an opticaL communica-tion system as sc~t forth in the preamble of claim 1.
Such system~ are known, e.g., frc,m a. Wedding et al, "10 Gbit!s to 260000 Sub,cribers Using Optical Amplifier D;str;bu.ion Net,~ork", Contribution for ICC/Supe~comm '9~, Opti~a~ Commurlicatic)ns 300 Level Session, "Impact o~ Opt;cal Am~liFiers or, ~etwork Architectures".
In such ofticdl comrnunication systems, ;n which the trans-mission llnk is ~ fiber-optic link, optical amplifiers serve to a.~plify optical iignals transmitted through the Optical wave~3uides.
The opti~a' amplifier chosen ;n the embodiment described below ;5 a fiber-optic amp'ifier. A fiber-opt;c ampl;-fier -is s~o~n in EP O 457 34~ A2, for examPle.
In such fiber-opi~ic amplifiers, erb;urn ions with which a sect;on .~f optical waveguide is doped are raised from a ground s tate to an exc ited state by pump light em;tted b~ a pumf) sourcc~ and from the excited state, the ions drop back, throlgh e;ther spontaneous or stimu-lated emissiorl, to th~ ground state. The st;m~lated emis-sion is e~ited oy the optical signal to be amplified, ~3~
whirh tra~els thtowgh the section of doped optical wave-gu;rle. Th ~pont~neou~; emiss;on is also amplif;ed ;n the doped ~;ection o~ opt-ical ~aveguide; this amplified spontaneou ~mi~ion (A5~) causes the noise internal to a fiber-opti(: amplifie~
In the ab~e-menlionec' syste~, there is the danger that ;n the ev~,;t of a break -in the fiber-optic l;nk, e.g., du~ tc fit,er br~ak3~e or to separat;on of a f;be~-optic con-,e~t~r, s~stem components, such as pho~od;odes, will be da!naged.
This carl l~? eYplained as foLlo~s:
As a re~u~ of the break ;n the fiber-optic link, the powe~ input to the op~ical amplifier decrea~es to zero. Since the pumping process ;s independent of the power input, er,ergy will be pumped ;nto the dooed oDt;cal-waveouide section even if the power ;nput has dropped, so th~t com-plete populc,t;on ;nversion w;ll occur. When light which re~ul~s from sp-)ntaneous emiss;on and is reflect-ed at thc interf~ce o~ the break in the fiber-opt;c l1n~ i)asse~ ~hro~lgh the section of doped optical wave~uide,whose active l~ser medium, e.g., erb;um ;ons, ;s ;n the -invert~d stat~, the stored enerc~y will be suddenly re~eas~d. High energy pulses w;ll be emitted which are a danyer to s~stem components.
These g;ant pul~es oropagate both in and opposite to the direct;ol, Df signal tlow. In the case of erb;um-doped fiber-optic ampl;fiers, the wavelength of the gi~nt pulses is ~n the range between 15Z0 nm and 1570 nm.
_ 3 _ ;~372~
Such fit)el~-()ptic a~plifi~rs are not only used in optical communica~ion ~stems~ ine~ are also employed in assem-blies ~1 Iro~isional setu~)s which are provided for the start-up ~J~ s~ch s~stems to permit measurements, tests, or step~ st~p installation. Reflecting surfaces may be intention,.lly or u~inten~ionally inse~ted in these set-ups and mil~ tnen cause back reflection of the light amplificd ~, the amplifier. Such reflecting surfaces are formei~ ln particular by a connect;ng element or a cut-off end of t1n optical waveguide.
An optica~ ampli~ier witl, a section of doped optical waveeu;de mây h.lve such a high gain that, if subjected, for exam~.!e, to unintentional back reflection, it will turn into 3 Lase~ GSCi llator due to a phenomenon called "Q-switchlr;y". ~hiC, too~ ~uses hi~h-energy pulses wh;ch nldy ~anlaQe system components. A known solution to the probl-r~ of how to avoid such daraage consists of insertin3 or,e or more op~ical isolators in the optical transmissicn path. These isolators can transmit l;ght ;n only one direction, whereby back reflect;ons are prevent-ed. Thus, t~,e optical amplifier can be prevented from operatin~ as a laser oscil~ator. OPtical isolators are the p~ssi e components with the highest complexity and, thus, the ri~hest price in a system or an optical ampli-fier with GptiCa l waveguide.
It is the o~ject of the in~ention to prov;de an optical communic~;ior~ ~yst~m co~r;sing optical amplifiers where-in th~ da~;~er of s,stem comPonents being damaged by high-energ~ ~u~ies i~ a~oided.
~37~l~
Th;s Oi~ je~:L i.~ a~.tainr:(i as set forth i.n claim 1 Further advantar~r~ous as~ct-s of ~he invention are defined in the subclainl~.
The in~rltion will no~. be explaineci in rnore detail with reference tc the accompar\ying d~w;ngs, in which:
fig 1 sr;J~S on~ r-mbodin~ent ~f an optical cr~mmuni-ca~;on system wi~h power ~imiters in accor-d;,~ce wi~:h the invent;on, Fig~ ~ lr:Oh'S th.~ attenuation of a power limiter as a f~n~;tion of the optical power input to the l,m;ter, c~nc-i Fig. 3 slow~ a riber-optic amplifier ~ith a oower lim;ter for ar, optical communication sys-t e m .
Fig. 1 sho~s an optical colnmunication system with an elec-trical-to-optical. ~ransduGer ~ at the transmitting end and one ol:.t.ical-!:o-ei~eç.trical transducer 3 at the re-ceiving er,l, which ar~ interconnected by an optical ~iaveguide 5. A colnmunicaiic)n system ~iith an electrical-tO-OptiCd trans~iucer at the transmitt;ng end and two or more ci~tribuied optir:al-to-electr;cal transducers at the receivir-g end ;s also ~ossible. This is of no con-sequence t or' tile invention The commuricatioa ~ystem of Fig 1 f~rther includes a fiber-opt c amPlifier 1 and two power l;miters 4.
- s- 2~372~
In this e~bodimeilt, as scer~ in the direction of propa-gat;on uf the oprical sigl13l, one power limiter 4 is ~ ted 1~ead ol the ~ibel-o~tic amplifier an~ one be-hind the .~mplifiar~ and they ~re implemented as sec-tions of (1 ped optic~l wa~egu;de. The two power (imiters are joine(~ to the fiber-~p~;c ampl;fier 1 and the optical wav~guide i ~-sin~ conventional splicin~ tethn;ques.
The power limitels ma~ also be imple~ented differentLy, e.g., as ~idtPle.s of abcjc,rb;ng mater;al which are in-serted i" the signal path at breaks in the Opticdl h'3Ve~Uide, e.g., in front of and behind the opt;c-" amplif;er, respectivelyA
Th;s abs"rbing matericll has p~operties wl1ich are de-srribed bll~w It is a~s~ po~3ible to place one power limiter behind the electricaL-t~-opt-ical transducer ~ and one in front of the op;ical-to-electr;cal transducer 3. This pro-tects thes~ system components from the effects of giant pul~es.
In pr3cti(al use, ~ibPr-,~pt;c amplifiers are also arransed n cascide. ]n that case, each of the links between the ;ndi~inual ~iber-optic amplifiers may con-tain one ~!ower limiter.
The power limiter has the following properties.
The po~er ~imit~r passes the optica~ signal with a normal ' : .' ~ 6 ~ 372~
optical ~ wl~r (a few !O nw~ and a wavelength of, e.g., ~ 15SO rm nearly unattenlJated. ~y contrast, it stron~ly atter\ucl'-e~; opti~al powers which correspond to that cf ti ~? gi3nt pulse ~watt ranye).
This is illustrated in ~i~. 2. The power ratio T = PtL~
Po is plo~te(, dS d fur;ction of the optical power input P~
to the ~ow~ iter. P(~) is the optical power output of a powe~ limiter of length L.
The depen{ierlce of the attenuation in the power li~iter is prefcrally nolline3r~ as shown in F;g. 2, so that high-power opt;cal ra~-Jiation w;ll be attenuated d;s-proportionately.
This ~tt~n~atior\ in the power lim;ter can be providedby ~;ght (attering. and/or absorption. The power li~;ter is preferai~ly ma~e of an absorbing material in which the absor~;tion i~ a two-~hoton process. The latter exhibits ;he part;cularly suitable nonlinear dependence of the op'ical input power. Th;s absorption is de-scribed, 10r exa~ple, in a book by r~R. Shen, "The Principle: ~f Nonlinear optics", John Wiley ~ Sons, pp. 202-2 ~), but nct in connection with a particular matarial r(ld not in connection ~;th optical waveguides.
The aforelknt;o~ rec~uiremc?ntS are fulfiLled, for examp~e, '~ a s~ction of doped optical waveguide made ~3~2~
of an abio!~,irlg n~aterial with two-photon absorpti~n.
Such an diJsort~ g mat~rial is neodymium~ Nd, or thu~i~;m, ''m, fo~ e~ample.
i~y an app!ot~riate cholce of the dop~nt and the doping concentra!;on in an optical waveguide, two-photon ab-sorl~tion is caused. The attenuation of the power limi~er i~, determ;ned by the length of the section of doped optical wavregui~.
~he fiber-o~tic amplifier ~iven as an example in ~i~. 3 tomprise. Lae fo'lo~ g elements, whose operation is ~nown from the alove-cited literature:
-- A st?ct i~ n of daped optical waveguide 33, wh;ch i5 doped wit~, e g , erbium i~ns and is capable of ~ccumulating CXCitatiQn energy suppl;ed by a pump source. 'le settion nf optical waveguide has two ends 35, 36.
- A pump ource 50~ which emits pump light.
- P~mp~lignt-couplilg means~ These means consist of a pump~ ht-:,oupling fiber 31 and a coupler 32.
Their fun(tion i~ to teed the putnp light into the section of t~opeti optical waveguide 33~
- A power limiter 4, shown here in the form of a section of ~ptiral wa~ey:Jide, contains a core with a semicorl-'uctiny absorbing material which is distri-buted ;n the core in the torm of microcrYstal-lites. Thij material is chosen to ha~e an absorption coefficien~ wh;ch increa!ieci ~ith increasing optical input pow~r, The absorption is a two-photon ~rocess.
-~- 20~372~
Preferabt~, the ab~or~irl~ material is a semiconduotor of the t~e ~ I, parttcularly cadmium telluride, CdTe.
The power li~iter is preferably connected in series with the ~ection of doped optical waveguide 33 by a splice ~4.
If the doping a~en~ is ionized erbium, Er , the ab-sorbing semieon~luc~or material will have a band glp correspundin~ to a wavelength between 750 nm and 1550 nm.
Gl~sses d(,ped with se~i~onductor m;crocrystallites were examined wi~h regard to ehe;r twû photon absorpt;on:
coefricients ~f 0.2 cm/GW were measured by F. Canto, E. M;esah et a~ (CLEO'88, Poster WM41) for the case where thY absor~t;on in the longitudinal direction is negl;gible (the energy of the photon is less than th~
band ga~). These results can be applied to optical wave-guides.
If, with such a coeff;c-ient (0.2 cm/GW), ;t ;s to be ensured that a ~,ower of 5W (10 MW/c~ ) is not exceeded in an opt ical communication system, and the loss to be ;nduced is 30 dtl, a power lim;ter implemented as an op-tical h~a~eguide ~Ust have a length of 30 m. The corres-ponding loss dt a power of 50 mW ;s then 0.3 dB.
Claims (9)
1. A communication system for transmitting an optical signal over an optical waveguide (5), comprising at least one optical amplifier (1), an electrical-to-op-tical transducer (2) at the transmitting end, and at least one optical-to-electrical transducer (3) at the receiving end, c h a r a c t e r i z e d i n that the opticak transmission path includes a power limiter (4) whose absorption coefficient increases with increasing optical input power.
2. A communication system as claimed in claim 1, characterized in that the power limiter (4) is a sec-tion of doped optical waveguide made of an absorbing material wherein the absorption is a two-photon process.
3. A communication system as claimed in claim 2, characterized in that the absorbing material is neodymium, Nd.
4. a communication system as claimed in claim 2, characterized in that the absorbing material is thulium, Tm.
ZPL/S-He/Ke/Lo T. Pfeiffer 6 05.04.93
ZPL/S-He/Ke/Lo T. Pfeiffer 6 05.04.93
5. A communication system as claimed in claim ?, characterized in that the power limiter (4) is a sec-tion of optical waveguide wherein a light-absorbing and semiconducting material is distributed in the form of microcrystallites, and wherein the absorption is a two-photon process.
6. A communication system as claimed in claim5, characterized in that the absorbing material is a semi-conductor material of the type II-VI.
7. A communication system as claimed in claim 6, characterized in that the absorbing material is cad-mium telloride, CdTe.
8. A communication system as claimed in claim 7, characterized in that the light-absorbing and semicon-ducting material has a band gap corresponding to a wave-length between 750nm and 1550 nm.
9. An optical amplifier for a communication system as claimed in any one of the preceding claims, c h a r a c t e r i z e d i n that the power limiter and the optical amplifier form a unit.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9204505 | 1992-04-13 | ||
| FR9204505A FR2689982B1 (en) | 1992-04-13 | 1992-04-13 | FIBER OPTICAL AMPLIFIER AND OPTICAL SYSTEM COMPRISING SUCH AN AMPLIFIER. |
| DEP4229292.1 | 1992-09-02 | ||
| DE19924229292 DE4229292C2 (en) | 1992-09-02 | 1992-09-02 | Optical communication system with a power limiter for giant impulses |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2093724A1 true CA2093724A1 (en) | 1993-10-14 |
Family
ID=25918155
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002093724A Abandoned CA2093724A1 (en) | 1992-04-13 | 1993-04-08 | Optical communication system with a power limiter for high-energy pulses |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0565993B1 (en) |
| JP (1) | JPH06102546A (en) |
| CA (1) | CA2093724A1 (en) |
| DE (1) | DE59301374D1 (en) |
| DK (1) | DK0565993T3 (en) |
| ES (1) | ES2085067T3 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074963A (en) * | 1990-07-27 | 1991-12-24 | The Goodyear Tire & Rubber Company | Furnish composition |
| DE19647488A1 (en) * | 1996-11-16 | 1998-05-20 | Alsthom Cge Alcatel | Optical amplifier for optical transmission system |
| US6134372A (en) * | 1997-10-01 | 2000-10-17 | Sumitomo Osaka Cement Co., Ltd. | Light intensity attenuator and attenuating method |
| GB9814252D0 (en) | 1998-07-02 | 1998-09-02 | Marconi Gec Ltd | Optical power detection |
| US7840098B2 (en) * | 2005-01-20 | 2010-11-23 | Intel Corporation | Variable optical power limiter |
| JP2011002543A (en) * | 2009-06-17 | 2011-01-06 | Nippon Telegr & Teleph Corp <Ntt> | Optical fuse |
| JP5059221B2 (en) * | 2011-09-13 | 2012-10-24 | 日本電信電話株式会社 | Optical limiter circuit and optical receiver circuit |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2219126A (en) * | 1988-05-27 | 1989-11-29 | Stc Plc | Laser and optical amplifiers |
| US4846561A (en) * | 1988-06-21 | 1989-07-11 | The United States Of America As Represented By The Secretary Of The Army | Monolithic optical power limiter based on two-photon absorption |
| US4973125A (en) * | 1989-08-25 | 1990-11-27 | National Research Council Of Canada | All optical self limiter for fiber optics |
-
1993
- 1993-04-06 DE DE59301374T patent/DE59301374D1/en not_active Expired - Fee Related
- 1993-04-06 ES ES93105651T patent/ES2085067T3/en not_active Expired - Lifetime
- 1993-04-06 EP EP93105651A patent/EP0565993B1/en not_active Expired - Lifetime
- 1993-04-06 DK DK93105651.9T patent/DK0565993T3/en active
- 1993-04-08 CA CA002093724A patent/CA2093724A1/en not_active Abandoned
- 1993-04-13 JP JP5086488A patent/JPH06102546A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE59301374D1 (en) | 1996-02-22 |
| DK0565993T3 (en) | 1996-02-12 |
| EP0565993B1 (en) | 1996-01-10 |
| ES2085067T3 (en) | 1996-05-16 |
| EP0565993A1 (en) | 1993-10-20 |
| JPH06102546A (en) | 1994-04-15 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |