CN1302329C - Gain flattened equalizer of erbium doped fiber amplifier based on chirped fiber grating - Google Patents
Gain flattened equalizer of erbium doped fiber amplifier based on chirped fiber grating Download PDFInfo
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- CN1302329C CN1302329C CNB2004100109852A CN200410010985A CN1302329C CN 1302329 C CN1302329 C CN 1302329C CN B2004100109852 A CNB2004100109852 A CN B2004100109852A CN 200410010985 A CN200410010985 A CN 200410010985A CN 1302329 C CN1302329 C CN 1302329C
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Abstract
The present invention relates to a gain flattened equalizer of an erbium doped fiber amplifier based on a chirped fiber grating, which belongs to the field of optical communication. The gain flattened equalizer comprises a laser (1) and a chirping phase mask plate (4), wherein fiber (10) and the mask plate (4) are arranged on an electric control translation platform (5). A real-time detecting system of the grating is composed of an ASE light source (7), a coupler (8) and a spectral analyzer (9). The corresponding wavelength range of the linear chirping phase mask plate covers a C wave band, the period of the C wave band is linearly enlarged along a length direction, and the enlarging amplitude of adjacent periods is consistent. A gain spectrum or a spontaneous radiation spectrum of the optical amplifier is analyzed by using software to obtain a control function which is used for fabricating the chirped fiber grating, and the chirped fiber grating is fabricated by using a program control scanning and exposing method according to the function. The gain flattened method of the present invention is simple and practical and has a small flattened error, a fabrication parameter of the fiber grating can be rapidly regulated by aiming at gain spectrums or spontaneous radiation spectrums of different optical amplifiers, and a fabricated device has small size and can be packed in a temperature compensation mode.
Description
Technical field:
The invention belongs to optical communication field, particularly be used to make gain of EDFA flattener and flat gain method based on chirped fiber grating.
Background technology:
Erbium-Doped Fiber Amplifier (EDFA) (EDFA) is being brought into play important effect in the jumbo optical communication system of long distance at a high speed.But the uneven phenomenon of the gain that image intensifer exists, limiting amplifier is in the particularly application in the wdm system of communication system.In order to make whole communication band need the image intensifer of flat gain to make each channel obtain smooth amplification, the technology that adds gain flattening filter (GFF) in image intensifer has obtained paying attention to and development.
At present, several technology can be used to make gain flattening filter, wherein mainly comprise film filter technology, long period fiber grating technology etc.With the close prior art of the present invention is the application for a patent for invention of disclosed CN1309307A on the 22nd in August calendar year 2001, and name is called " long period fiber grating flattener and method for designing thereof ".The structure of flattener comprises ultraviolet laser, catoptron, post lens, optical fiber, white light source, spectrometer, platform.Optical fiber is fixed on the platform and can be installed with the amplitude mask version on optical fiber with the translation of platform by the vertically moving of optical fiber.The method for designing of flattener, adopting the weakly guiding optical fiber method of approximation that vector field is converted into scalar field finds the solution, obtain the characteristic parameter of optical fiber through secular equation, further obtain the propagation constant of cladding mode, utilize phase-matching condition to obtain relation between fiber-optic periodic and optical wavelength and mode order again, thereby design the long period fiber grating device that satisfies different needs.
Loss is less though the long period fiber grating technology is inserted, and it is big also to exist smooth error function, and device size is big, and wavelength is along with temperature and the big shortcoming of bending change drift.
Summary of the invention:
The technical problem to be solved in the present invention is, utilize linear chrip phase mask plate and programme controlled scan exposure fabrication techniques chirped fiber grating in broadband, this fiber grating has and the corresponding to reflectance spectrum of light amplifier gain spectral line, utilize this chirped fiber grating uneven partial reflection in the amplifier gain spectrum can be fallen like this, reach the purpose of planarization; And can overcome disadvantages of background technology, and making the method simple and flexible, device insertion loss is little, and the planarization error function is little, and size is little, and temperature susceplibility is lower.
In order to achieve the above object, the present invention has adopted the light amplifier gain flat device of following apparatus and method making based on chirped fiber grating:
A kind of gain of EDFA flattener based on chirped fiber grating, by the ultraviolet light process mirror reflects of excimer laser emission, vertical irradiation is on mask plate after the post lens focus, and mask plate is placed on the optical fiber; Optical fiber and mask plate are placed on the electronic control translation stage; The motion of laser energy and transmission frequency and electronic control translation stage is by computer control.With background technology different be that the real-time detecting system of grating is made up of amplified spont-aneous emission (ASE) light source, coupling mechanism and spectroanalysis instrument; Said mask plate is the phase mask plate of warbling, and the wavelength coverage of linear chrip phase mask plate correspondence covers C-band; The cycle of mask plate increases along its length direction is linear, and the increase amplitude between the adjacent periods is consistent.
Making based on the method for the light amplifier gain flat device of chirped fiber grating is:
1, resolves the spontaneous emission spectrum (ASE) or the gain spectral of image intensifer, obtain the pairing gain size of each wavelength (unit is dB) in the gain bandwidth (GB) scope, utilize Origin then, softwares such as AutoCAD fit it, thereby obtain in the gain spectral bandwidth with wavelength X
GThe gain function f (λ) that changes.
2, with wavelength X
GWith the warble wavelength X at phase mask plate different cycles place of wide-band linearity
MBe mapped.The wavelength coverage of linear chrip phase mask plate correspondence is about 40nm, can cover C-band.The cycle of mask plate increases along its length direction is linear, and the increase amplitude between the adjacent periods is consistent.Like this can be with wavelength X
GBe mapped with the period position on the mask plate.
3, obtain the reflective function R (λ) of the chirped fiber grating that will make according to gain function f (λ).The principle of following is to be reference point with gain point minimum in the gain function curve, and the gain size (unit is dB) that each wavelength place exceeds reference point is the reflection size of this wavelength place chirped fiber grating.
4, because before the fiber grating amount of selling off did not reach capacity, the grating reflection rate was write fashionable exposure with grating and is become linear approximate relationship, so the grating reflection function can be changed into exposure function E (λ).
5, exposure function E (λ) is converted to the control function of fiber grating ablation process.In pulsed frequency one timing of laser energy and emission, the movement velocity of exposure and the electronic control translation stage relation of being inversely proportional to, so E (λ) can convert the motion control function of electronic control translation stage to; In electronic control translation stage movement velocity one regularly, exposure and laser energy and transmission frequency are proportional, so E (λ) can convert the control function of laser energy and transmission frequency to.
6, according to the control function of making chirped fiber grating, utilize aforesaid device on enhanced sensitivity optical fiber, to utilize the scan exposure method to write chirped fiber grating, so just can produce the chirped fiber grating gain flattener.
Making of the present invention is simple and direct flexibly based on the method for the light amplifier gain flat device of chirped fiber grating, can be according to the spectral shape of the different gain spectral design chirped fiber grating of EDFA, adjust the making parameter of fiber grating rapidly, produce satisfactory gain flattener.Little with the device insertion loss that this method is made, the planarization error function is little, size little (chirp value of mask plate is big owing to warble, size is little), and temperature susceplibility is lower, carries out the temperature compensation encapsulation easily.
The present invention is applicable to the design and the making of image intensifer spontaneous emission spectrum and gain spectrum flattening device in the optical communication field.Utilize method of the present invention design and make light amplifier gain flat device based on chirped fiber grating and all belong to the present invention and protect category.
Description of drawings
Fig. 1 is the apparatus structure synoptic diagram of the light amplifier gain flat device based on chirped fiber grating of the present invention.
Fig. 2 is a kind of spontaneous emission spectrum of the Erbium-Doped Fiber Amplifier (EDFA) without planarization.
Fig. 3 is the spectrogram at the chirped fiber grating gain flattener of the making of the spectral line among Fig. 2.
Fig. 4 is that Fig. 2 is through the smooth spontaneous emission spectrum of chirped fiber grating.
Fig. 5 is the spontaneous emission spectrum of another kind of Erbium-Doped Fiber Amplifier (EDFA).
Fig. 6 is the spectrogram at the chirped fiber grating gain flattener of the making of the spectral line among Fig. 5.
The spontaneous emission spectrum of the Erbium-Doped Fiber Amplifier (EDFA) that Fig. 7 is Fig. 5 after smooth.
Embodiment:
The apparatus structure of the embodiment 1 accompanying drawings light amplifier gain flat device based on chirped fiber grating of the present invention.
As Fig. 1, the ultraviolet light of excimer laser 1 emission focuses on the back vertical irradiation on the phase mask plate 4 of warbling through catoptron 2 reflections and post lens 3, laser beam forms interference fringe by mask plate 4 backs on optical fiber 10, and make the fiber core refractive index generating period variation of optical fiber 10, thereby form grating.Optical fiber 10 and mask plate 4 are placed on the electronic control translation stage 5.The motions of laser energy and transmission frequency and electronic control translation stage 5 etc. are by computing machine 6 controls.The real-time detecting system of grating is by ASE light source 7, and coupling mechanism 8 and spectroanalysis instrument 9 are formed.
Said mask plate 4 is the phase mask plates of warbling, and the wavelength coverage of linear chrip phase mask plate correspondence is 40nm, can whole covering C-band; The cycle of mask plate 4 increases along its length direction is linear, and the increase amplitude between the adjacent periods is consistent.
Embodiment 2
Fig. 2 represents is a kind of spontaneous emission spectrum of the Erbium-Doped Fiber Amplifier (EDFA) without planarization, at first this spectrum is resolved and is fitted, and has obtained the gain function curve f (λ) in 1525nm-1560nm gain bandwidth (GB) scope; Then each wavelength in the gain bandwidth (GB) scope and wide-band linearity being warbled, different positions is mapped on the phase mask plate; With near the lowest gain point the 1538nm in the gain function curve as reference point, the reflective function R (λ) that is higher than the chirped fiber grating that the gain size of reference point will make exactly in the gain bandwidth (GB) is converted into reflective function the exposure function E (λ) of grating again; Then, the motion control function with exposure function E (λ) changes electronic control translation stage into utilizes this control function and scan exposure fabrication techniques chirped fiber grating, as shown in Figure 3; At last fiber grating is carried out the spontaneous emission spectrum of image intensifer as flattener smooth, as shown in Figure 4.
As can see from Figure 4, EDFA gain spectral unevenness degree reaches the practicability requirement less than ± 0.5dB on the bandwidth of 30nm.
Fig. 5 is the spontaneous emission spectrum of another kind of Erbium-Doped Fiber Amplifier (EDFA), adopts the method for making of the present invention based on the light amplifier gain flat device of chirped fiber grating, produces satisfactory gain flattener.Fig. 6 represents is the spectrogram of the chirped fiber grating gain flattener made at the spectral line among Fig. 5; Fig. 7 represents is the spontaneous emission spectrum of the Erbium-Doped Fiber Amplifier (EDFA) after smooth.
As can see from Figure 7, being about on the gain bandwidth (GB) of 30nm EDFA gain spectral unevenness degree, reach the practicability requirement less than ± 0.5dB.
Claims (1)
1, a kind ofly it is characterized in that based on the smooth method of the gain of EDFA of chirped fiber grating,
---resolve the spontaneous emission spectrum or the gain spectral of image intensifer, obtain the pairing gain size of each wavelength in the gain bandwidth (GB) scope, utilize Origin then, AutoCAD software fits it, obtains in the gain spectral bandwidth with wavelength X
GThe gain function f (λ) that changes;
---with wavelength X
GWavelength X with the phase mask plate different cycles position of warbling
MBe mapped;
---obtain the reflective function R (λ) of the chirped fiber grating that will make according to gain function f (λ), be reference point promptly with gain point minimum in the gain function curve, each wavelength place exceeds the gain size of reference point, is the reflection size of this wavelength place chirped fiber grating;
---according to before the fiber grating amount of selling off does not reach capacity, the grating reflection rate is write fashionable exposure with grating and is become linear approximate relationship, changes the grating reflection function into exposure function E (λ);
---exposure function E (λ) is converted to the control function of fiber grating ablation process, promptly regularly in the pulsed frequency one of laser energy and emission, the movement velocity of exposure and the electronic control translation stage relation of being inversely proportional to, therefore E (λ) converts the motion control function of electronic control translation stage to, in electronic control translation stage movement velocity one regularly, exposure and laser energy and transmission frequency are proportional, so E (λ) converts the control function of laser energy and transmission frequency to;
---according to the control function of making chirped fiber grating, utilize gain of EDFA flattener, on enhanced sensitivity optical fiber, write chirped fiber grating with the scan exposure method based on chirped fiber grating.
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| CNB2004100109852A CN1302329C (en) | 2004-07-09 | 2004-07-09 | Gain flattened equalizer of erbium doped fiber amplifier based on chirped fiber grating |
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| CN1302329C true CN1302329C (en) | 2007-02-28 |
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Families Citing this family (11)
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| CN100422838C (en) * | 2005-09-08 | 2008-10-01 | 中国计量学院 | Flat gain Chirp Bragg optical fibre grating wave filter used for optical amplifier |
| CN101374025B (en) * | 2007-08-22 | 2012-08-29 | 昂纳信息技术（深圳）有限公司 | Method for determining spectrum shape of light amplifier gain flat filter |
| CN102193150A (en) * | 2011-04-27 | 2011-09-21 | 暨南大学 | Method and device for preparing adjustable edge filter based on all-fiber technology |
| CN103308977B (en) * | 2013-06-08 | 2016-08-10 | 北京品傲光电科技有限公司 | Fiber grating carving and writing method that a kind of bandwidth is controlled and device |
| CN104020522A (en) * | 2014-05-30 | 2014-09-03 | 暨南大学 | Broadband tuning chirp inclined optical fiber bragg grating band-stop filter and manufacturing device and method thereof |
| CN105610513B (en) * | 2015-12-21 | 2017-10-10 | 太原理工大学 | A kind of chaotic laser light emitter detected for communication cabinet fault |
| CN106533552B (en) * | 2016-10-27 | 2019-03-19 | 武汉光迅科技股份有限公司 | Optical power and gain detection device and method under a kind of image intensifer burst mode |
| CN112946812B (en) * | 2021-01-12 | 2022-10-11 | 河南渡盈光电科技有限公司 | Preparation method of dispersion-controllable large-bandwidth chirped fiber grating |
| CN114153018A (en) * | 2021-10-21 | 2022-03-08 | 之江实验室 | Reflectivity control method and manufacturing device of weak reflection grating based on movable lens system |
| CN114156721A (en) * | 2021-12-02 | 2022-03-08 | 长飞光纤光缆股份有限公司 | Gain flat optical fiber amplifier based on temperature-locking optical fiber grating and control method thereof |
| CN116413852B (en) * | 2023-06-05 | 2023-09-19 | 湖北工业大学 | Method and system for realizing dense wide reflection spectrum channels |
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| US20030059161A1 (en) * | 2001-09-26 | 2003-03-27 | Jeong-Hwan Song | Gain flattening device for an optical fiber amplifier |
| US20030179997A1 (en) * | 2002-03-21 | 2003-09-25 | Hwang Seong-Taek | Gain flattening filter and gain flattened optical fiber amplifier employing the same |
| US20030185509A1 (en) * | 1998-12-04 | 2003-10-02 | Bailey Timothy J. | Optical grating-based filter |
| US20030202745A1 (en) * | 2002-04-29 | 2003-10-30 | Alcatel. | Apodised complex filter |
| CN1151395C (en) * | 2001-01-23 | 2004-05-26 | 吉林大学 | Long-period optical fibre raster gain flattener and its design method |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030185509A1 (en) * | 1998-12-04 | 2003-10-02 | Bailey Timothy J. | Optical grating-based filter |
| CN1151395C (en) * | 2001-01-23 | 2004-05-26 | 吉林大学 | Long-period optical fibre raster gain flattener and its design method |
| US20030059161A1 (en) * | 2001-09-26 | 2003-03-27 | Jeong-Hwan Song | Gain flattening device for an optical fiber amplifier |
| US20030179997A1 (en) * | 2002-03-21 | 2003-09-25 | Hwang Seong-Taek | Gain flattening filter and gain flattened optical fiber amplifier employing the same |
| US20030202745A1 (en) * | 2002-04-29 | 2003-10-30 | Alcatel. | Apodised complex filter |
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