CN210897967U - Second-order Raman amplifier of equidirectional pumping - Google Patents
Second-order Raman amplifier of equidirectional pumping Download PDFInfo
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- CN210897967U CN210897967U CN201922341671.5U CN201922341671U CN210897967U CN 210897967 U CN210897967 U CN 210897967U CN 201922341671 U CN201922341671 U CN 201922341671U CN 210897967 U CN210897967 U CN 210897967U
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Abstract
The utility model provides a second order raman amplifier of syntropy pumping, include: the signal input end is connected with the signal end of a first signal pump wave combiner, the reflection end of the first signal pump wave combiner is connected with the forward combined Raman pump light source, the common end of the first signal pump wave combiner is connected with one end of a transmission optical fiber, the other end of the transmission optical fiber is connected with one end of a fiber grating, and the other end of the fiber grating is connected with the signal output end; the forward combined Raman pump light source comprises a coherent light source and a polarization-independent incoherent light source, and specifically comprises a pump combiner, a pump beam splitter, a high-order pump source, an optical fiber circulator and a section of single-mode optical fiber. The second-order Raman amplifier of the same-direction pump can restrain RIN noise from the forward Raman amplifier, reduce ASE noise and improve system performance.
Description
Technical Field
The utility model relates to an optical amplifier, especially be arranged in the second order raman amplifier of a syntropy pumping of optical communication and optical transmission system.
Background
In the early 90 s, erbium-doped fiber amplifiers (EDFAs) were successfully developed; the low noise amplifier has low noise, large bandwidth of the amplifier, compatibility with a wavelength division multiplexing WDM system, high pumping efficiency, stable working performance and mature technology, and is favored in the modern long-distance wavelength division multiplexing optical fiber communication system; however, the gain spectrum of the EDFA can only cover the C-band 1529-1561nm and the L-band 1570-1610 nm. And the quartz single-mode fiber has a bandwidth of dozens of THz (40nm) in a low-loss window of a 1.55 mu m wave band, and is far from being fully utilized. The presence of a Raman Fiber Amplifier (RFA) compensates for this drawback, which theoretically can amplify signals of any wavelength, provided that there is a suitable pump light source. In practice, the most common is an inverted raman amplifier. The homodyne raman amplifier brings about severe crosstalk between pump and signal and severe Relative Intensity Noise (RIN) and ASE noise due to the high pump light and signal light power simultaneously entering the transmission fiber. Generally, to ensure that Q degradation does not exceed 1dB, relative intensity noise below-120 dB/Hz is required for co-pumping and below-90 dB/Hz for counter pumping. Low RIN pumps tend to produce SBS which increases the pump RIN and is transferred to the signal by the fast raman response, causing signal damage.
Disclosure of Invention
To the deficiencies that exist in the prior art, the utility model provides a second order raman amplifier of syntropy pumping. The forward pump light of the amplifier consists of a coherent second-order pump laser and an incoherent first-order broadband light source, and a coherent and incoherent pump light source is simultaneously and dynamically provided by one second-order pump laser by adopting a smart optical structure. The forward pumping Raman amplifier effectively avoids the disadvantages of large intrinsic RIN noise and high ASE noise of a forward pumping mode, can improve the performance of an optical transmission system and reduce the cost of the amplifier and the system. The utility model adopts the technical proposal that:
the method comprises the following steps: the signal input end is connected with the signal end of a first signal pump wave combiner, the reflection end of the first signal pump wave combiner is connected with the forward combined Raman pump light source, the common end of the first signal pump wave combiner is connected with one end of a transmission optical fiber, the other end of the transmission optical fiber is connected with one end of a fiber grating, and the other end of the fiber grating is connected with the signal output end; the forward combined Raman pump light source consists of a coherent light source and an incoherent light source, and comprises: the reflection end of the first signal pump wave combiner is connected with the common end of the pump wavelength wave combiner, one input end of the pump wavelength wave combiner is connected with one output end of the pump beam splitter, the other input end of the pump wave combiner is connected with an optical fiber circulator port 3, and an optical fiber circulator port 2 is connected with a section of single-mode optical fiber and an APC joint jumper; the other output end of the pumping beam splitter is connected with the port 1 of the optical fiber circulator, and the input end of the pumping beam splitter is connected with a high-order pumping source.
Further, the transmission direction of the fiber optic circulator (304) is along port 1- > port 2- > port 3 thereof.
Further, the pump wavelength of the high-order pump source (303) is 1365 nm.
Further, the pump beam splitter (302) is an adjustable beam splitter, and the beam splitting ratio of the two output ends is adjustable from 10% to 90%.
Furthermore, the reflection wavelength of the fiber grating (5) is between 1430 nm and 1480nm, and the reflection bandwidth is 0.5 nm.
Further, the reverse Raman pump light source (7) is a second-order Raman pump laser with the wavelength of 1365 nm.
Further, the transmission fiber is a single mode fiber, and the length of the transmission fiber is more than 75 km.
Further, a single mode fiber (305) is 10km long and is used for generating incoherent first order pump light, and the output end of the single mode fiber is connected with an APC joint jumper.
Furthermore, two input ends of the pumping wavelength combiner (301) have wavelength selectivity, and the wavelength passed by one end connected with the pumping beam splitter (302) is 1300-1400 nm; the wavelength of one end connected with the optical fiber circulator (304) is 1410-1490 nm; the common end of the pumping wavelength (301) passes through the wavelength of 1300-1500 nm.
The utility model has the advantages that:
the coherent light source and the incoherent light source are combined to reduce RIN noise and ASE noise brought by the forward Raman pump structure. In addition, the cost of the amplifier and the transmission system can be reduced.
Drawings
Fig. 1 is a schematic view of the structure of the present invention.
Detailed Description
The invention is further described with reference to the following specific drawings and examples.
As shown in fig. 1, a second order raman amplifier pumped in the same direction comprises: the Raman signal source comprises a signal input end, a first signal pumping wave combiner, a forward combined Raman pumping light source, a transmission optical fiber, an optical fiber grating, a second signal pumping wave combiner, a reverse Raman pumping light source and a signal output end;
the signal input end is connected with the signal end of a first signal pump wave combiner, the reflection end of the first signal pump wave combiner is connected with the forward combined Raman pump light source, the common end of the first signal pump wave combiner is connected with one end of a transmission optical fiber, and the other end of the transmission optical fiber is connected with one end of a fiber grating and is connected with the signal output end;
the forward combined Raman pump light source comprises a reflecting end of a first signal pump wave combiner (2) and a common end of a pump wavelength wave combiner (301), wherein an input end of the pump wavelength wave combiner (301) is connected with an output end of a pump beam splitter (302), the other input end of the pump wave combiner (301) is connected with a port 3 of an optical fiber circulator (304), and the port 2 of the optical fiber circulator (304) is connected with a section of single-mode optical fiber (305) and an APC joint jumper (306); the other output end of the pump beam splitter (302) is connected with the port 1 of the optical fiber circulator (304), and the input end of the pump beam splitter (302) is connected with a high-order pump source (303).
The transmission direction of the optical fiber circulator (304) is along port 1- > port 2- > port 3;
the pumping wavelength of the high-order pumping source (303) is 1365 nm;
the pump beam splitter (302) is an adjustable beam splitter, and the beam splitting proportion of the two output ends is adjustable from 10% to 90%.
Raman amplification works by the third-order nonlinear effect-stimulated raman scattering-of intense laser light as it propagates through an optical fiber. After the pump light with proper wavelength and power is transmitted to the optical fiber for transmitting optical signals, the signal light can be amplified in the optical fiber by utilizing the stimulated Raman scattering effect. The very broad peak gain position of the gain spectrum of raman scattering is at frequency shift 13 THz. If strong light with frequency about 13THz higher than that of the signal light is used for pumping, the power of the pumping light is transferred to the signal light due to the Stokes process of stimulated Raman scattering, so that the signal light is amplified.
The wavelength of the high-order Raman pump source is 1365nm, after passing through the pump beam splitter 302, a part of the high-order Raman pump source enters a 10km single-mode fiber 305, a Stokes spectrum is formed in the single-mode fiber due to the Raman scattering effect, the center wavelength of the spectrum is near 1455nm, and the 3dB bandwidth of the spectrum is greater than 30 nm.
For example, the splitting ratio of the pump beam splitter 302 is adjusted to 50: and 50, when the output power of the high-order pump source is 6W, the power distributed to the port 1 of the optical fiber circulator by the pump beam splitter is 3W, second-order pump light output from the port 2 of the optical fiber circulator enters 10km single-mode optical fiber, a broadband Stokes spectrum is formed in the single-mode optical fiber due to the Raman scattering effect, the power is about 30mW, and the central wavelength of the Stokes spectrum is 1455 nm. The part of broadband light source power enters the optical fiber circulator from a port 2 of the optical fiber circulator, is output from a port 3, and then enters the pump combiner 301 through one end (the transmission wavelength 1 is 1410-1490 nm). The 2 nd order raman pump light split at the other end of the pump beam splitter 302 with a power of 3W enters the pump combiner 301 through the other end of the pump combiner (with a transmission wavelength of 1300-1400 nm). Thus, the pump light from the two input ends of the pump combiner 301 are coherent second-order pump light with a wavelength of 1365nm and incoherent first-order broadband pump light, which enter the reflection end of the signal pump combiner 2 after being output from the pump combiner 301, and then enter the transmission fiber 4 after being output from the common end of the signal pump combiner 2. The transmission fiber is a raman gain fiber. In the gain fiber, the second-order pump light firstly amplifies broadband first-order pump light through the stimulated Raman scattering effect, and the amplified first-order pump light further amplifies input signal light. The forward combined Raman pump light source formed by the method inhibits strong RIN noise and ASE noise brought by the traditional forward pump structure.
On the other hand, the second-order pump light entering the gain fiber, the fiber grating and the gain fiber form a random Raman laser resonant cavity. The method includes the steps that firstly, Raman lasing is achieved for 1365nm laser in a gain optical fiber, a fiber grating serves as a frequency selection device, a frequency spectrum of a wavelength corresponding to the fiber grating is selected and amplified, the reflection wavelength of the grating is located between 1430 nm and 1480nm, and light in the wavelength range corresponds to the wavelength of a first-order Raman pump source of an input signal. Furthermore, the first-order Raman pump source which is selected and amplified transfers power to signals in the gain fiber, and further amplifies the input signals.
The syntropy Raman pump light formed by the structure comprises first-order pump light and second-order pump light, and the second-order pump light, the fiber bragg grating and the gain fiber form a random Raman resonant cavity. The resultant force of the two components realizes the structure of the bidirectional pump. Moreover, due to the matching of the coherent light source and the incoherent light source, the signal degradation effect possibly brought by the co-directional pumping is overcome; further, the performance of the transmission system is obviously improved.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the scope of the claims of the present invention.
Claims (6)
1. A co-pumped second order raman amplifier, comprising: the Raman pump comprises a signal input end (1), a first signal pump wave combiner (2), a forward combined Raman pump light source (3), a transmission optical fiber (4), an optical fiber grating (5) and a signal output end (6);
the signal input end (1) is connected with the signal end of the first signal pumping wave combiner (2), the reflection end of the first signal pumping wave combiner (2) is connected with the forward combined Raman pump light source (3), the common end of the first signal pumping wave combiner (2) is connected with one end of the transmission optical fiber (4), the other end of the transmission optical fiber (4) is connected with one end of the optical fiber grating (5), and the other end of the optical fiber grating (5) is connected with the signal output end (6).
2. A co-pumped second order Raman amplifier according to claim 1, wherein the forward combined Raman pump light source (3) further comprises,
the reflection end of the first signal pump combiner (2) is connected with the common end of the pump combiner (301), one input end of the pump combiner (301) is connected with one output end of the pump beam splitter (302), the other input end of the pump combiner (301) is connected with the port 3 of the optical fiber circulator (304), the port 2 of the optical fiber circulator (304) is connected with a section of single-mode optical fiber (305), and the output end of the single-mode optical fiber is connected with an APC joint jumper (306); the other output end of the pump beam splitter (302) is connected with a port 1 of a fiber circulator (304), and the input end of the pump beam splitter (302) is connected with a high-order pump source (303);
the transmission direction of the optical fiber circulator (304) is along port 1- > port 2- > port 3;
the pumping wavelength of the high-order pumping source (303) is 1365 nm;
the pump beam splitter (302) is an adjustable beam splitter, and the beam splitting proportion of the two output ends is adjustable from 10% to 90%.
3. A co-pumped second order Raman amplifier according to claim 1,
the reflection wavelength of the fiber grating (5) is between 1430 nm and 1480nm, and the reflection bandwidth is 0.5 nm.
4. A co-pumped second order Raman amplifier according to claim 1,
the transmission fiber is a single-mode fiber, and the length of the transmission fiber is more than 75 km.
5. A co-pumped second order Raman amplifier according to claim 1 or 2,
the forward combined Raman pump light source (3) comprises a single-mode optical fiber (305) with the length of 10km, the function of the single-mode optical fiber is to generate incoherent first-order pump light, and the output end of the single-mode optical fiber is connected with an APC joint jumper.
6. A co-pumped second order Raman amplifier according to claim 1 or 2,
the two input ends of a pumping wave combiner (301) included in the forward combined Raman pumping light source (3) have wavelength selectivity, and the passing wavelength of one end connected with a pumping beam splitter (302) is 1300-1400 nm; the wavelength of one end connected with the optical fiber circulator (304) is 1410-1490 nm; the common end of the pump combiner (301) passes through the wavelength of 1300-1500 nm.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114243437A (en) * | 2021-12-08 | 2022-03-25 | 武汉邮电科学研究院有限公司 | PON system based on centralized Raman fiber amplifier and optical amplification method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114243437A (en) * | 2021-12-08 | 2022-03-25 | 武汉邮电科学研究院有限公司 | PON system based on centralized Raman fiber amplifier and optical amplification method |
| CN114243437B (en) * | 2021-12-08 | 2023-12-22 | 武汉邮电科学研究院有限公司 | PON system based on centralized Raman fiber amplifier and optical amplification method |
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