CN1265240C - Low-noise variable-gain optical amplifier - Google Patents
Low-noise variable-gain optical amplifier Download PDFInfo
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- CN1265240C CN1265240C CN 02126616 CN02126616A CN1265240C CN 1265240 C CN1265240 C CN 1265240C CN 02126616 CN02126616 CN 02126616 CN 02126616 A CN02126616 A CN 02126616A CN 1265240 C CN1265240 C CN 1265240C
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- doped fiber
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- erbium
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Abstract
The present invention provides a low-noise adjustable-gain optical amplifier. By dividing an Erbium-doped fiber into two sections, an adjustable optical attenuator is connected in the middle of the front section of Erbium-doped fiber and the rear section of Erbium-doped fiber. The power gain of the front section of Erbium-doped fiber is larger than the insertion loss of the middle adjustable optical attenuator. The gain adjustment of the optical amplifier is realized by regulating the optical attenuator. The front section of Erbium-doped fiber and the rear section of Erbium-doped fiber work under the gain locked condition. The front section of Erbium-doped fiber keeps lower noise, and the coefficient of absorption takes 2-4 dB/m, and thereby, the integral noiseproof feature of the amplifier is improved. The front section of amplifier can also use a one-way pumping source with 980 nm wavelength (forward direction or backward direction) and can also uses a bi-directional pumping source with 980 nm wavelength to improve the noiseproof feature. An isolator and a gain flattening filter are also added between the two sections of Erbium-doped fibers. The optical attenuator can be an adjustable optical attenuator, a mechanical adjustable optical attenuator, etc.
Description
Technical field
The present invention relates to a kind of low-noise variable-gain optical amplifier, the low-noise variable-gain optical amplifier that particularly utilizes two sections Er-doped fibers to realize is used for the WDM optical transmission system.
Background technology
Several stages has been experienced in the development of optical transmission system, and a wherein very important stage is exactly the appearance and the application of Erbium-Doped Fiber Amplifier (EDFA) (EDFA).Before EDFA occurs, but optical transmission system is influenced by fibre loss, laser output power and receiver received power directly, and the without electronic relay transmission range generally is no more than the 40-80 kilometer.After EDFA occurred, maximum constraints factor---the restriction of fibre loss of having broken the optical transmission system transmission range made that light signal need not just can transmit farther distance after photoelectricity light conversion (OEO) regeneration.The image intensifer model basically identical in this period, light signal just need amplify again through an image intensifer website behind transmission one segment distance and enters optical fiber transmission once more, this moment, the main limited resource of optical transmission system was the noise accumulation that the image intensifer cascade brings, noise accumulation degree and image intensifer power input, noise of optical amplifier correlation of indices.
Present image intensifer has three kinds of mode of operations substantially: gain locking, power blockage and electric current locking.Gain locking type amplifier is commonplace, and power input is within the specific limits the time, and amplifier output power and power input are directly proportional, and the gain-type amplifier can be regarded a kind of shallow degree saturation type amplifier basically as.Power blockage type amplifier is used and will be lacked relatively, and when it is characterized in that power input changes within the specific limits, its output power is constant substantially, and power blockage type amplifier is generally operational in the degree of depth state of saturation.The locking-typed amplifier of electric current is the pumping current of control pumping source, and control pumping light intensity size and power blockage type amplifier are similar a bit, actually rare at present.
In dwdm system, the common mode of operation of amplifier all is a gain locking.In dwdm system, often have about the channel, cause the amplifier power input that change is arranged, guarantee that the best way that each channel power does not change allows amplifier be operated in the gain locking state exactly.But the shortcoming that this amplifier exists is to make the amplifier of different size to the different size dwdm system, can't use identical amplifier as 80 kilometers sections of striding with 100 kilometers sections of striding.Though can add before and after amplifier that optical attenuator reaches the difference section of striding and uses identical amplifier, add that in front optical attenuator makes the power input of amplifier to reduce, influential to system's Optical Signal To Noise Ratio; Add optical attenuator in the amplifier back and make that then system's peak power output is limited, the reason of this two aspect has all limited the application of complete gain locking type amplifier in long distance, ultra long haul system.
In addition, the front had been put forward amplifier noise crucial the rising of the influence of system's Optical Signal To Noise Ratio had been determined in the power input of amplifier and the noise figure of amplifier.Increasing and require the longer distance of no electrical transmission, dwdm system pair amplifier to propose the requirement of low noise and big output power along with the number of channel in the dwdm system.But well-known, the amplifier that the single hop Er-doped fiber is made into is in its output power during near its saturation output power, the serious deterioration of noise figure, and this dwdm system that wave number is increased is a stern challenge.
Summary of the invention
The objective of the invention is to utilize two sections Er-doped fibers to realize the low noise and the Gain Adjustable of image intensifer in the WDM optical transmission system, make it to reach: 1, Gain Adjustable does not produce the existing Optical Signal To Noise Ratio of system and has a strong impact on; 2, noiseproof feature deterioration can not occur under the big output power condition.
Technical scheme of the present invention is: Er-doped fiber is divided into two sections, realize the Gain Adjustable of image intensifer by two sections Er-doped fibers in front and back and the middle adjustable optical attenuator that inserts, wherein the power gain that provides of leading portion Er-doped fiber is greater than the Insertion Loss of the adjustable optical attenuator of centre, described image intensifer is regulated its gain by the damping capacity that changes described adjustable optical attenuator, thereby realizes the different requirements to gaining under the multiple span loss.
Described low-noise variable-gain optical amplifier, two sections Er-doped fibers all are to be operated under the gain locking state before and after it.
Described low-noise variable-gain optical amplifier also adds optoisolator between two sections Er-doped fibers.
In order to guarantee low-noise performance, leading portion Er-doped fiber absorption coefficient gets 2-4d B/m and the leading portion Erbium-Doped Fiber Amplifier (EDFA) adopts 980hm wavelength pumping source can choose one or use simultaneously wantonly.
Between described adjustable optical attenuator and back segment Er-doped fiber, add gain flattening filter, can improve overall optical Amplifier Gain flatness.
Before the leading portion Er-doped fiber He after the back segment Er-doped fiber, optoisolator is set, prevents of the influence of this amplifier, also avoided the next stage amplifier that amplifier at the corresponding levels is impacted the upper level amplifier.
Advantage of the present invention is: at first be no longer to need adjustable optical attenuator to adjust amplifier before and after the amplifier; Next is to have avoided using before and after the amplifier the additional light signal to noise ratio (S/N ratio) deterioration that optical attenuator brings and the power budget of increase; Moreover be that a kind of specification of amplifier of the present invention just can adapt to the multiple section of striding loss, the too much problem of amplifier specification of effectively having avoided the different sections of striding to use different amplifier specifications to be brought.
Description of drawings
Fig. 1 is original gain locking type amplifier principle schematic.
Fig. 2 is that two sections Er-doped fibers are realized low noise gain adjustable type method of light amplification principle schematic.
Fig. 3 is a kind of specific embodiment structural representation of two sections Er-doped fiber optical amplification devices.
Embodiment
Gain-type amplifier originally is one section Erbium-Doped Fiber Amplifier (EDFA), sees Fig. 1.The pumping source that uses has 980 and the pumping source of two kinds of wavelength of 1480nm, and the amplifier under this structure just the problems referred to above can occur.
Low-noise variable-gain optical amplifier principle such as Fig. 2 that two sections Er-doped fibers that the present invention proposes are realized: it mainly is made up of three parts: leading portion Er-doped fiber, VOA (adjustable optical attenuator), back segment Er-doped fiber.The front and rear sections Er-doped fiber can be regarded a gain-type amplifier separately as, and both directly link together by VOA.
Er-doped fiber is divided into two sections, adds adjustable optical attenuator in the centre, the power gain that the leading portion Er-doped fiber provides is greater than the Insertion Loss of the adjustable optical attenuator of centre.By regulating optical attenuator, realized gain adjustable amplifier.
The concrete structure of implementing is seen Fig. 3: Er-doped fiber is divided into two section 1 and 2, between the amplifier 1 and 2 of front and back section EDF formation, crosstalk in the actual design, and obtain better gain flatness, the centre has also added isolator 7,8 and gain flattening filter 6, and isolator can only be established one.Can also isolator all be set in the front and back of two sections EDF amplifiers, as 9 among the figure, 10.Like this, be to prevent that this amplifier to the influential while of upper level amplifier, also having avoided the next stage amplifier that amplifier at the corresponding levels is impacted.A wave multiplexer 4,5 is all arranged before and after the EDF optical fiber, be used for 1480 pump lights and 1550 flashlights are combined and enter EDF (Er-doped fiber) and amplify.Between the amplifier that two sections Er-doped fibers constitute, an optical attenuator 3 and a gain flattening filter 6 are arranged, optical attenuator is used for controlling the external gain of whole amplifier, and gain flattening filter then is to be used for improving overall optical Amplifier Gain flatness.Because optical attenuator is used in the middle part of amplifier, neither can reduce the power input (when being placed on the amplifier front) of image intensifer because of the intrinsic Insertion Loss of optical attenuator, cause equivalence to reduce to the noise of optical amplifier index, can (when being placed on the amplifier back) not cause restriction to the image intensifer peak power output yet, this is for DWDM (dense wave division multipurpose demultiplexing) system, and is especially significant.Optical attenuator can be electric-controlled adjustable optical attenuator, mechanical adjustable optical attenuator.As long as it is adjustable.
What is more important: amplifier of the present invention does not have the devices such as pumping source of pair amplifier to propose too high requirement, the Gain Adjustable that it is realized is to be undertaken by the mode of stage casing loss fully, therefore the influence of the pump power of pair amplifier is also not obvious, has effectively promoted the utilization ratio of pump power.
In addition, though because two sections EDF are the settings of gain locking type amplifier, both also have some differences.Leading portion EDF uses 980nm wavelength pumping source, promptly among the figure 11, can be unidirectional 980nm wavelength pumping source (forward direction or back to), also can be two to 980nm wavelength pumping source, in order to prevent that pumping from crosstalking, need between pump laser and wave multiplexer, add isolator sometimes.In order to obtain reasonable noiseproof feature, the leading portion Er-doped fiber is kept than low noise.Method is that leading portion Er-doped fiber absorption coefficient is got 2-4d B/m and adopted 980nm wavelength pumping source can choose one wantonly, just can reach effect preferably, not high to its demanded power output, the power gain of leading portion Er-doped fiber gets final product greater than the Insertion Loss of the adjustable optical attenuator of centre.Back segment EDF then is in order to obtain than higher output power, to satisfy the dwdm system needs, as among the figure 12, can adopt 1480 pumpings, also can use 980nm wavelength pumping source.
The noise figure of present segment EDF is NF1, gain for G, optical attenuator maximal value be that (when the noise figure of L＜G), back segment EDF was NF2, then the equivalent noise index of this amplifier was L: NF1+10lg (1+10
(NF2-NF1+L-G)/10).Because compare the relation of NF2 and NF1, G is much larger than L, can use the NF1 equivalence so NF2-NF1+L-G＜0, the noise figure that promptly means amplifier are in fact approximate, noiseproof feature that also can pair amplifier when L adjusts within the specific limits makes a big impact.Therefore, two sections Er-doped fiber amplifying stage the earth of the present invention have improved the performance of the fine amplifier of making of single hop erbium, and have only just realized the amplifier of low noise figure with smaller cost.
Core of the present invention is the Gain Adjustable enlarging function of realizing by two sections Er-doped fibers in front and back and the middle adjustable optical attenuator that inserts.Therefore, two sections Er-doped fibers are realized Gain Adjustable and are obtained reasonable noiseproof feature before and after every utilization, all belong to protection domain of the present invention.
Claims (8)
1, a kind of low-noise variable-gain optical amplifier that is applied in the wdm system, described image intensifer adopts Erbium-Doped Fiber Amplifier (EDFA), it is characterized in that described image intensifer is made up of two sections Er-doped fibers in front and back and the middle adjustable optical attenuator that inserts, wherein the power gain that provides of leading portion Er-doped fiber is greater than the Insertion Loss of the adjustable optical attenuator of centre, described image intensifer is regulated its gain by the damping capacity that changes described adjustable optical attenuator, thereby realizes the different requirements to gaining under the multiple span loss.
2, low-noise variable-gain optical amplifier according to claim 1, two sections Er-doped fibers all are to be operated under the gain locking state before and after it is characterized in that.
3, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that also adding optoisolator between two sections Er-doped fibers.
4, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that leading portion Er-doped fiber absorption coefficient gets 2-4dB/m.
5, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that the leading portion Erbium-Doped Fiber Amplifier (EDFA) adopts 980nm wavelength pumping source.
6, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that adding gain flattening filter between described adjustable optical attenuator and back segment Er-doped fiber.
7, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that before the leading portion Er-doped fiber optoisolator being set.
8, low-noise variable-gain optical amplifier according to claim 1 and 2 is characterized in that after the back segment Er-doped fiber optoisolator being set.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02126616 CN1265240C (en) | 2002-07-18 | 2002-07-18 | Low-noise variable-gain optical amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02126616 CN1265240C (en) | 2002-07-18 | 2002-07-18 | Low-noise variable-gain optical amplifier |
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| Publication Number | Publication Date |
|---|---|
| CN1469180A CN1469180A (en) | 2004-01-21 |
| CN1265240C true CN1265240C (en) | 2006-07-19 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 02126616 Expired - Lifetime CN1265240C (en) | 2002-07-18 | 2002-07-18 | Low-noise variable-gain optical amplifier |
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Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7317570B2 (en) * | 2006-05-12 | 2008-01-08 | Bookham Technology Plc | Variable gain optical amplifiers |
| WO2014177224A1 (en) * | 2013-05-03 | 2014-11-06 | Huawei Technologies Co.,Ltd. | Method for assigning launch powers to an arrangement of physically coupled fiber spans |
| CN104410444B (en) * | 2014-12-25 | 2018-03-02 | 武汉光迅科技股份有限公司 | A kind of not damaged synchronous handover protector for dynamic optical line |
| CN107342822A (en) * | 2016-04-29 | 2017-11-10 | 中兴通讯股份有限公司 | Power regulating method and device, optical communication system for optical network unit |
| CN106785833B (en) * | 2016-12-06 | 2019-04-23 | 江苏黑马高科股份有限公司 | A kind of erbium-doped fiber amplifier of power limiting gain controllable |
| CN110061407B (en) * | 2018-01-18 | 2020-08-07 | 武汉奥新科技有限公司 | Gain range adjustable erbium-doped optical fiber amplifier optical path |
| 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 |
| CN109120370B (en) * | 2018-07-27 | 2020-05-12 | 武汉光迅科技股份有限公司 | DWDM remote pumping system capable of improving OSNR |
| CN112310791B (en) * | 2020-10-23 | 2021-10-12 | 武汉光迅电子技术有限公司 | Gain adjusting method and optical fiber amplifier |
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- 2002-07-18 CN CN 02126616 patent/CN1265240C/en not_active Expired - Lifetime
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