CN1238934C - Low noise index gain blocked erbium-doped amplifier - Google Patents
Low noise index gain blocked erbium-doped amplifier Download PDFInfo
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- CN1238934C CN1238934C CNB031166040A CN03116604A CN1238934C CN 1238934 C CN1238934 C CN 1238934C CN B031166040 A CNB031166040 A CN B031166040A CN 03116604 A CN03116604 A CN 03116604A CN 1238934 C CN1238934 C CN 1238934C
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Abstract
The present invention relates to a low noise index gain blocked erbium-doped amplifier which belongs to the technical field of optical communication. Signal light provided by a tunable laser is input into an input port 1 of a 90/10 optical coupler, 90% of output ports of the 90/10 optical coupler are connected to an isolator, the other end of the isolator is connected with a port 1550 of a wavelength (1550/980 nm) selection coupler, a port 980 of the wavelength (1550/980 nm) selection coupler is connected with a pumping laser (980 nm), the other end of a wavelength interleaving multiplexer is connected with an erbium-doped optical fiber, the other end of the erbium-doped optical fiber is connected with an isolator and then is connected to an input end of the wavelength interleaving multiplexer, even number output ports of the wavelength interleaving multiplexer are connect to a spectrum analyzer, and odd number output ends of the wavelength interleaving multiplexer are connected to an input port 2 of the 90/10 optical coupler to form a sealed annular cavity. Amplified signal light of the present invention can singly output without laser, and the noise index is low. The present invention can be used for different WDM systems matched with the present invention through changing the types of the wavelength interleaving multiplexer.
Description
Technical field
What the present invention relates to is a kind of erbium-doped fiber amplifier, and the gain blocked erbium-doped fiber amplifier of particularly a kind of low noise figure belongs to the optical communication field.
Background technology
Along with the fast development of optical communication, the application of fiber amplifier in trunk optical-fiber network and metropolitan area network system all more and more paid attention to by people.Especially erbium-doped fiber amplifier (EDFA) has played landmark effect to the development of dense wave division multipurpose (DWDM) system.For be applied to dwdm system to erbium-doped fiber amplifier, gain blocked, perhaps be called gain balance, be an important characteristic, what of the size of input signal power in the system and channel the amplification performance that it guarantees erbium-doped fiber amplifier do not rely on.There are many schemes can solve gain blocked problem in the common erbium-doped fiber amplifier, the gain blocked structure that two kinds of band optic fiber ring-shaped cavities are arranged at present: a kind of is the co-propagate structure, in this structure, signal and laser are propagated along same direction, thereby the amplifier noise index is lower, but shortcoming is can not separation signal light and laser; Another kind is the backpropagation structure, and signal and laser backpropagation can easily signal and laser be made a distinction, but the amplifier noise index are higher.Therefore, in traditional gain blocked Er-doped fiber loop laser amplifier, low noise figure and signal separate output with laser and are difficult to satisfy simultaneously.
Find by literature search, people such as the Cai Ming of Tsing-Hua University, Liu Xiaoming publish thesis " Study on NoiseCharacteristics of Gain-Clamped Erbium-Doped Fiber-Ring LasingAmplifier (research of gain controlling Er-doped fiber loop laser amplifier noise index) ", IEEE Photon.Technol.Lett., vol.9, NO.8, AUGUST 1997 (being published in the electric Engineering society of U.S. photoelectron technology wall bulletin in August, 1997).Gain of EDFA control is to realize by the loop laser chamber in the document, by changing the direction of isolator in the annular chamber, can obtain the gain controlling EDFA of different performance.Compared the noise figure performance difference of EDFA under three kinds of situations in the literary composition emphatically, promptly the isolator direction is consistent with isolator direction outside the chamber in the laser cavity, no isolator in the opposite and chamber.These three kinds of propagation conditions respectively have its pluses and minuses.When the inside and outside isolator direction in chamber is opposite, flashlight is identical with the laser propagation direction, be called the co-propagate situation, export existing amplifying signal light in the light this moment, the laser of exporting in the annular chamber is also arranged, therefore amplifying signal light and laser separately can't be exported, but its advantage is that noise figure is less that the document obtains the noise figure of 5.1dB.When the isolator direction was identical inside and outside the chamber, flashlight and laser were propagated in opposite direction, at this moment, the impact of amplifying signal light Stimulated Light, noise figure increases (6.1dB), can not export together with amplifying signal light but its advantage is laser.As there not being isolator in the fruit caving, then the laser in the chamber is propagated along both direction, and this is a kind of situation of compromise, it also is the worst situation, its noise figure does not reach good effect between top two kinds of situations (5.5dB), can not obtain independent amplifying signal light output simultaneously again.The present invention designs with regard to the starting point that is based on the above-mentioned situation of solution.
Summary of the invention
The objective of the invention is to overcome deficiency of the prior art, provide a kind of low noise figure gain blocked erbium-doped fiber amplifier, by in light path, using the wavelength interleaver (Interleaver) of a 100G/200G, gain is clamped down on, solve above-mentioned two problems that are present in traditional gain blocked Er-doped fiber annular amplifier, the flashlight that promptly is exaggerated can not contain the independent output of laser, and because flashlight and the co-propagate of laser and the filter action of wavelength interleaver obtain lower noise figure.
The present invention is achieved by the following technical solutions, the present invention mainly comprises: 90: 10 optical coupler, first isolator, second isolator, wavelength selective coupler, semiconductor laser diode, the wavelength interleaver, variable optical attenuator, tunable laser, spectroanalysis instrument (OSA), Er-doped fiber, the 980nm pump laser, its connected mode is: the flashlight that is provided by tunable laser is input to 1 input port of 90: 10 optical couplers of 2 * 2, optical coupler 90% output port was connected to first isolator in 90: 10, the other end of first isolator connects 1550 ports of 1550/980nm wavelength selective coupler, and its 980 port connects the 980nm pump laser; The other end of wavelength interleaver connects Er-doped fiber (EDF), and the other end of Er-doped fiber connects one second isolator again, receives the input of wavelength interleaver then; The even number output port of wavelength interleaver is connected to spectroanalysis instrument (OSA), detects amplifying signal light, and its odd number output is connected to 2 input ports of 90: 10 optical couplers of 2 * 2 by a variable attenuator, form a closed annular chamber.
The used flashlight of the present invention can be provided by tunable laser and/or multiple-wavelength laser; 90: 10 optical coupler (OC) is with in 90% the flashlight coupled into optical fibres annular chamber; Two isolators (OI1 and OI2) make flashlight and laser one way propagation; 1550/980 wavelength selective coupler (WSC) is imported Er-doped fiber (EDF) with flashlight and laser coupled together; Semiconductor laser diode (LD), the 980nm pump light of output 90mw; The odd number termination of wavelength interleaver is gone into light path, directly is fed back into annular chamber from the spontaneous amplification radiation of wavelength interleaver odd number end output and produces laser, and its even number end then is used to export amplifying signal; Variable optical attenuator (voa) also can be formed by the coupler cascade of a plurality of different splitting ratios, is used to the locking gain that changes the loss of annular chamber and then change flashlight; Tunable laser or multi-wavelength high stable laser are respectively applied for input single channel and multi-channel signal light; Spectroanalysis instrument (OSA) is used to test input/output signal luminous power, gain and noise figure.
The present invention adopts 100Ghz/200Ghz wavelength interleaver to be applicable to 200Ghz dense wavelength division multiplexing system at interval; Adopt the wavelength interleaver of 50Ghz/100Ghz, then 100Ghz dense wavelength division multiplexing system at interval; Perhaps adopt the wavelength interleaver of 25Ghz/50Ghz, then be applicable to 50Ghz dense wavelength division multiplexing system.The present invention can substitute wavelength-division multiplex system as the multichannel input signal source with the multiple-wavelength laser that a wavelength interleaver with 100Ghz/200Ghz is complementary.
At first measure the output spectral line of wavelength interleaver even number end because the wavelength interleaver is a comb filter, thereby only with it the flashlight that matches of the output spectral line of even number output just can obtain amplifying.Regulate tunable laser, make its output wavelength can pass through the even number end of wavelength interleaver just, and each output wavelength of multi-wavelength high stable laser all can be by the even number end of wavelength interleaver.Be fed into annular chamber from the spontaneous emission spectrum of wavelength interleaver odd number end output, enter Er-doped fiber then again and obtain amplifying, the wavelength interleaver of this moment is equivalent to a path to this part light.So move in circles, the light of certain wavelength is constantly amplified and is suppressed the amplification of its commplementary wave length because power is relatively strong, and finally the light of this wavelength forms laser in annular chamber.In this device, the flashlight that is exaggerated and laser coexistence and co-propagate, thereby the present invention can regard the community of laser and amplifier as.The existence of oscillating laser makes that the gain of flashlight is clamped down in the chamber.On the one hand, the existence of stabilized lasers makes that the number average particle counter-rotating of Er-doped fiber is fixing, thereby makes the gain constant of flashlight.From another point of view, when oscillating laser was stablized, laser energy was constant in the chamber, and in order to keep the conservation of energy, it is constant that the gain of flashlight also must keep.Gain constant means that what of the watt level of input signal light and input channel the gain of flashlight do not rely on.
Flashlight and laser co-propagate, make the noise figure of amplifier be lower than under the same terms oppositely and the two-way propagation situation.The wavelength interleaver has also played individual filter, it has filtered the spontaneous amplification radiant power of half in the output signal, spontaneous radiation power then is the main source of noise power, so the use of wavelength interleaver has reduced the noise figure of amplifier.Based on above-mentioned two reasons, the noise figure of amplifier of the present invention can reach very low standard.
The loss that changes annular chamber can change gain and noise figure.Cavity loss is low more, and the laser power of formation is strong more, can effectively suppress spontaneous amplification radiation more.Therefore low noise figure is also just low more more for cavity loss.But low noise figure is to be cost with the gain that reduces flashlight, because the enhancing of laser power has caused the decay of flashlight gain.
The present invention has substantive distinguishing features and marked improvement, compare with common gain blocked Er-doped fiber annular amplifier, the flashlight that the present invention is exaggerated can not contain the independent output of laser, and noise figure is lower, by changing the type of wavelength interleaver, the different wavelength-division multiplex systems that can make this amplifier be used for being complementary with it.
Description of drawings
Fig. 1 structural representation of the present invention
Embodiment
As shown in Figure 1, the present invention includes: 90: 10 optical coupler 1, first isolator 2 and second isolator 3, wavelength selective coupler 4,980nm pump laser 5, wavelength interleaver 6, variable optical attenuator 7, tunable laser 8, spectroanalysis instrument 9, Er-doped fiber 10, its connected mode is: the flashlight that is provided by tunable laser 8 is input to 1 input port of 90: 10 optical couplers of 2 * 2, optical coupler 90% output port was connected to first isolator 2 in 90: 10, the other end of first isolator 2 connects 1550 ports of 1550/980nm wavelength selective coupler 4, and its 980 port connects 980nm pump laser 5; The other end of wavelength selective coupler 4 connects Er-doped fiber 10, and the other end of Er-doped fiber 10 connects second isolator 3 again, receives the input of wavelength interleaver 6 then; The even number output port of wavelength interleaver 6 is connected to spectroanalysis instrument 9, and its odd number output is connected to 2 input ports of 90: 10 optical couplers 1 of 2 * 2 by variable optical attenuator 7, form a closed annular chamber.
Used flashlight is provided by tunable laser and/or multiple-wavelength laser in the work of the present invention.The odd number termination of wavelength interleaver 6 is gone into light path, directly is fed back into annular chamber from the spontaneous amplification radiation of wavelength interleaver 6 odd number ends output and produces laser, and its even number end is then exported amplifying signal.Variable optical attenuator 7 also can be formed by the coupler cascade of a plurality of splitting ratios.
The present invention adopts 100Ghz/200Ghz wavelength interleaver 6 to be applicable to 200Ghz wavelength-division multiplex system at interval; Adopt the wavelength interleaver 6 of 50Ghz/100Ghz, then 100Ghz wavelength-division multiplex system at interval; Perhaps adopt the wavelength interleaver of 25Ghz/50Ghz, then be applicable to the 50Ghz wavelength-division multiplex system.The present invention can substitute wavelength-division multiplex system as the multichannel input signal source with the multiple-wavelength laser that a wavelength interleaver 6 with 100Ghz/200Ghz is complementary.
The present invention is further illustrated below in conjunction with embodiment:
At first, by jockey shown in Figure 1, use a tunable laser source that has variable optical attenuator as the single channel input signal source.For the gain locking characteristic under competitive list channel and the multichannel input condition, import light source with the multiwavelength laser source of a high stable as multichannel, the even port output spectral line of its output spectral line and wavelength interleaver is identical substantially.At last, with an optical coupler of 50: 50 above-mentioned two light sources are coupled into this gain blocked amplifier input terminal mouth.The EXFO spectroanalysis instrument is all used in the measurement of input/output signal luminous power, gain and noise figure.Analyze explanation of the present invention characteristic with different luminous power inputs as embodiment below in conjunction with different wavelength numbers.
Embodiment one
With an optical coupler of 50: 50 single Wavelength tunable light source and multi-wavelength high stable lasing light emitter are coupled as the input signal source of amplifier.At first, select the 1554.97nm flashlight as the reference flashlight.In the measuring process, regulate two-laser, guarantee the output port at 50: 50 optical couplers, the input power of 1554.97nm flashlight keeps 20dBm.The measurement of single wavelength amplifying signal is to carry out under the condition that multiple-wavelength laser is closed.When cavity loss is 16dB, obtain the power output of 1554.97nm flashlight under multichannel and single channel initial conditions to be respectively-7.60dBm and-7.30dBm.By this experiment, can draw under two kinds of different initial conditions, the gain difference of same signal light can be ignored, also shown in amplifier of the present invention simultaneously, when cavity loss was 16dB, no matter how many channels were imported, and the flashlight of 1554.97nm all keeps the gain of about 12.6dB.
Embodiment two
In order to show the gain locking characteristic of amplifier of the present invention under different input power, need to measure the gain-input signal power variation relation under single channel and the multichannel initial conditions.Wherein, common amplifier does not promptly have the amplifier of annular chamber.Only consider the 1546.92nm flashlight in the experiment, because its power is the strongest in the output spectral line in high stable multiwavelength laser source, and it can be from the even number end output of wavelength interleaver.In traditional amplifier, single wavelength and multi-wavelength initial conditions gain down are basic identical with the input signal power variation relation, promptly gain and decay along with the increase of input signal power, and the gain of 1546.920nm wavelength reduced about 3dB when input channel increased simultaneously.Therefore, traditional EDFA obviously can not satisfy the increase and decrease of wdm system channel to the fixed requirement of gain steady.In gain blocked EDFA, single wavelength and multi-wavelength initial conditions gain with input signal power variation relation also basically identical down.Under two kinds of initial conditions, all the holding chamber loss is 18dB.In this gain blocked EDFA, gain is locked as 13.8dB and 13.4dB respectively under single wavelength and the multi-wavelength initial conditions.At the region of variation of input signal power from-30dBm to-5dBm, change in gain is less than 0.2dB.Under two kinds of initial conditions, the change in gain part of about 0.4dB is the junction loss that comes from measure error and spectroanalysis instrument.
Embodiment three
Experiment also draws the 1546.92nm flashlight under the different cavity loss, and its gain and noise figure are with the variation relation of input signal power.Common EDFA (can regard cavity loss as is infinitely-great gain blocked EDFA) under the small-signal initial conditions its gain and noise figure be respectively 28dB and 6.4dB.They are all decayed along with the increase of input signal power.And in gain blocked EDFA, when cavity loss was 24dB and 18dB, in the region of variation of-10dBm, gain was locked into 17.8dB and 14dB respectively to input signal power at-32dBm.The size that gain and dynamic gain are clamped down on zone (gain keeps stable input power region of variation) all changes along with the variation of cavity loss.Along with the minimizing of cavity loss, gain becomes more and more littler, and that dynamic gain is clamped down on the district is elongated.When cavity loss was respectively infinity, 24dB and 18dB, noise figure should be 6.4dB, 5.8dB and 4.2dB mutually.The reason that the noise figure of gain blocked EDFA is lower than common EDFA is, the inhibition that the laser power that annular chamber produces is strong the power of spontaneous amplification radiation, and spontaneous amplification radiation is the main source of noise.Cavity loss is low more, and the laser power of formation is strong more, can effectively suppress spontaneous amplification radiation more.Therefore low noise figure is also just low more more for cavity loss.But low noise figure is to be cost with the gain that reduces flashlight, because the enhancing of laser power has caused the decay of flashlight gain.
Claims (5)
1, the gain blocked erbium-doped fiber amplifier of a kind of low noise figure, comprise: the optical coupler of 90:10 (1), first isolator (2), second isolator (3), wavelength selective coupler (4), 980nm pump laser (5), variable optical attenuator (7), tunable laser (8), spectroanalysis instrument (9), Er-doped fiber (10), it is characterized in that also comprising: wavelength interleaver (6), its connected mode is: the flashlight that is provided by tunable laser (8) is input to 1 input port of 2 * 2 90:10 optical coupler (1), 90:10 optical coupler (1) 90% output port is connected to first isolator (2), the other end of first isolator (2) connects the 1550nm port of 1550/980nm wavelength selective coupler (4), and its 980nm port connects 980nm pump laser (5); The other end of wavelength selective coupler (4) connects Er-doped fiber (10), and the other end of Er-doped fiber (10) connects second isolator (3) again, receives the input of wavelength interleaver (6) then; The even number output port of wavelength interleaver (6) is connected to spectroanalysis instrument (9), and its odd number output is connected to 2 input ports of 2 * 2 90:10 optical coupler (1) by variable optical attenuator (7), form a closed annular chamber.
2, the gain blocked erbium-doped fiber amplifier of low noise figure according to claim 1 is characterized in that adopting 100Ghz/200Ghz wavelength interleaver (6) to be applicable to 200Ghz dense wavelength division multiplexing system at interval; Adopt the wavelength interleaver (6) of 50Ghz/100Ghz, then be applicable to 100Ghz dense wavelength division multiplexing system at interval, adopt the wavelength interleaver (6) of 25Ghz/50Ghz, then be applicable to 50Ghz dense wavelength division multiplexing system.
3, the gain blocked erbium-doped fiber amplifier of low noise figure according to claim 1 is characterized in that, perhaps uses multiple-wavelength laser that a wavelength interleaver (6) with 100Ghz/200Ghz is complementary as the multichannel input signal source.
4, the gain blocked erbium-doped fiber amplifier of low noise figure according to claim 1 is characterized in that, flashlight used in the work is provided by tunable laser and/or multiple-wavelength laser.
5, the gain blocked erbium-doped fiber amplifier of low noise figure according to claim 1 is characterized in that, variable optical attenuator (7) also can be formed by the coupler cascade of a plurality of splitting ratios.
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| CNB031166040A CN1238934C (en) | 2003-04-24 | 2003-04-24 | Low noise index gain blocked erbium-doped amplifier |
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| CNB031166040A CN1238934C (en) | 2003-04-24 | 2003-04-24 | Low noise index gain blocked erbium-doped amplifier |
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| CN1238934C true CN1238934C (en) | 2006-01-25 |
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Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1295560C (en) * | 2004-11-26 | 2007-01-17 | 中国科学院上海光学精密机械研究所 | Tunable narrow line optical fiber amplifier |
| CN101191972B (en) * | 2006-12-01 | 2010-09-08 | 中国科学院半导体研究所 | Tunable single-frequency erbium-doped optical fibre ring form cavity laser with stable output wavelength and power |
| CN102306894A (en) * | 2011-08-18 | 2012-01-04 | 厦门大学 | Graphene-based multi-wavelength Q-modulation rare-earth-doped fiber laser |
| CN102570257B (en) * | 2012-03-09 | 2014-04-09 | 中国科学院上海光学精密机械研究所 | Full optical fiber annular amplifier |
| CN107302175B (en) * | 2017-06-21 | 2019-10-22 | 安徽大学 | A kind of all-optical switch based on outfield auxiliary control |
| CN108539571B (en) * | 2018-04-08 | 2020-05-26 | 上海交通大学 | Rapid automatic mode locking method covering multi-state pulse recognition |
| CN108899749B (en) * | 2018-06-28 | 2019-10-11 | 无锡市德科立光电子技术有限公司 | Low noise figure erbium-doped fiber amplifier design optimization method |
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