Low-noise high-power two-stage amplifier
By adopting a low-noise, high-power dual-stage amplifier structure in optical fiber communication systems, and using the combination of components and isolators, the problem of low integration of traditional EDFA cascade structure is solved, and signal amplification with high gain, low noise and high output power is achieved, which is suitable for the miniaturization design of lasers.
Patent Information
- Application Number
- CN202422226159.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-09-11
AI Technical Summary
Traditional EDFA cascade structures require multiple isolators, resulting in low integration, which is not conducive to product miniaturization, and it is difficult to achieve high gain and low noise signal amplification at the same time.
Using a low-noise, high-power dual-stage amplifier structure, multiple components and isolators are arranged on the optical path, including narrowband filters and pump light reflectors, the effective isolation and combination of signal light and pump light are achieved, and the first-stage high-particle number inversion state is used to ensure high gain and low noise, and the second-stage improves the output power.
It realizes high gain and low noise signal amplification, reduces the impact of reverse ASE, and has high integration, which is suitable for the miniaturized design of lasers.
Smart Images
Figure CN223066618U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optics, in particular to a low-noise high-power two-stage amplifier. Background Technique
[0002] In an optical fiber communication system, an erbium-doped fiber amplifier (EDFA) can directly amplify an optical signal without converting the optical signal into an electrical signal.
[0003] The EDFA mainly consists of an erbium-doped fiber (EDF), a pump light source (980 nm or 1480 nm laser), an optical wavelength division multiplexer, an optical isolator, etc. The principle of signal amplification: when the signal light and the pump light are simultaneously injected into the erbium-doped fiber, erbium ions (Er3+) are excited from the ground state N1 to the high-energy level N2 under the action of the pump light and quickly decay to the metastable energy level N3. Electrons are accumulated at the metastable energy level N3, resulting in more electrons than the ground state, that is, population inversion is formed. Under the action of the incident signal light, the erbium ions in the metastable energy level N3 quickly transition to the ground state N1 and emit photons of the signal light (i.e., stimulated emission), so that the signal light is amplified.
[0004] The main characteristic indexes of the EDFA are gain and noise.
[0005] The purpose of the erbium-doped fiber amplifier is to provide gain. Its gain is defined as the ratio of the output signal to the input signal. The gain can be regarded as the difference between two signal values, and the expression is: G = 10Log10(Pout / Pin).
[0006] The gain of the EDFA is divided into two cases: small-signal gain and saturation gain. When the pump light power is very strong and the signal light power is very weak, the population inversion degree between the upper and lower levels is very high. Along the length direction of the erbium-doped fiber, the pump power is gradually converted into the power of the signal light, and the EDFA gain will reach a very high value. This kind of gain is called small-signal gain. As the incident light power gradually increases, the increase in erbium ions in the upper energy level will decrease due to insufficient compensation for losses, and the gain will not be able to maintain the initial value and gradually decrease. At this time, the EDFA enters the saturation state. Therefore, for a given pump light power, the maximum gain of the EDFA corresponds to an optimal erbium-doped fiber length value. When the erbium-doped fiber length exceeds the optimal value, the gain will rapidly decrease, and the excess erbium-doped fiber part will play a role in absorbing and amplifying the signal.
[0007] Another important parameter of the EDFA is noise. Noise is generated because during the signal amplification process, metastable particles not only transition to the ground state through stimulated emission but also through spontaneous emission. The generated photons are continuously amplified along the way, forming amplified spontaneous emission (ASE). Since ASE is superimposed on the signal light during signal amplification and its interaction with the signal light generates greater noise, the magnitude of the noise is related to the pump light power and the length of the erbium-doped fiber: the longer the erbium-doped fiber, the greater the noise (NF); as the pump light power increases, the population inversion increases and the noise decreases; when the pump light saturates the EDFA and the population inversion reaches its maximum value, the noise tends to a constant value.
[0008] The gain and noise of the amplifier are the most fundamental factors for system applications. To obtain a signal light with both high gain and low noise, using the correspondence between the noise figure and the gain, a cascaded amplifier form is usually adopted in actual amplifier production, and two-stage cascading is the most common.
[0009] Traditional EDFA cascading usually adopts a two-stage direct connection structure. Each stage consists of a pump laser, a wavelength multiplexer, and a gain medium erbium fiber. An isolator is used between the two stages to reduce the impact of reverse ASE, and isolators are set at both ends of each stage for isolation. Therefore, at least three isolators are required. At the same time, the integration of the traditional EDFA structure is low, which is not conducive to the requirements of product miniaturization. Utility Model Content
[0010] To solve the above problems of the prior art, the present utility model provides a low-noise high-power two-stage amplifier.
[0011] To achieve the above object, the main technical solutions adopted by the present utility model include:
[0012] A low-noise high-power two-stage amplifier includes a first component, a first active fiber, a second component, a second active fiber, and a third component arranged in sequence along the optical path direction; the first component is used to access the signal light and couple the signal light into the first active fiber; a first pump light source is provided between the first component and the second component; the pump light generated by the first pump light source is isolated in the first active fiber by the first component and the second component; the second component includes a narrowband filter for filtering; the output end of the second component is connected to the second active fiber; a second pump light source is provided between the second component and the third component; the pump light generated by the second pump light source is isolated in the second active fiber by the second component and the third component; the signal light is amplified in the first active fiber and the second active fiber and then output from the third component.
[0013] Further, the first component includes a first dual fiber optic head, a first birefringent crystal, a first wave plate, a first lens, a first pump light reflector, a first optical rotation crystal, a first partial reflection film, and a first photodiode arranged along the optical path direction; the first photodiode is used to detect and monitor the signal light partially transmitted through the first partial reflection film.
[0014] Further, the first dual fiber optic head includes a first optical fiber and a second optical fiber; the signal light is coupled into the first optical fiber; the wavelength of the signal light is 1550 nm; the second optical fiber is the output end and is connected to the first active optical fiber; the first partial reflection film reflects the signal light and couples it into the second optical fiber; the first pump light source is connected to the second component, and the first pump light reflector reflects the pump light reversely pumped by the first pump light source back into the second optical fiber to improve the utilization rate of the pump light.
[0015] Further, the second component includes a second dual fiber optic head, a second lens, a second pump light reflector, a narrowband filter, an isolator, a third pump light reflector, a third lens, and a single fiber optic head arranged along the optical path direction; the first pump light source is connected to the second component, and the second pump light reflector is used to reflect and couple the pump light generated by the first pump light source into the first active optical fiber; the second pump light source is connected to the third component, and the third pump light reflector is used to reflect and couple the pump light generated by the second pump light source into the second active optical fiber to improve the utilization rate of the pump light.
[0016] Further, the second dual fiber optic head includes a third optical fiber and a fourth optical fiber; the third optical fiber is connected to the first active optical fiber and is used to input the signal light after being amplified at the first stage; the fourth optical fiber is connected to the first pump light source and is used to input the pump light; the single fiber optic head includes a fifth optical fiber; the fifth optical fiber is the output end and is connected to the second active optical fiber.
[0017] Further, the third component includes a three-fiber optic head, a second birefringent crystal, a second wave plate, a fourth lens, a fourth pump light reflector, a second optical rotation crystal, a second partial reflection film, and a second photodiode arranged along the optical path direction; the second photodiode is used to detect and monitor the signal light after being amplified at the second stage and partially transmitted through the second partial reflection film.
[0018] Further, the three-fiber optic head includes a sixth optical fiber, a seventh optical fiber, and an eighth optical fiber; the sixth optical fiber is connected to the second pump light source and is used to input the pump light; the seventh optical fiber is connected to the second active optical fiber; the eighth optical fiber is the output end and is used to output the signal light after being amplified at the second stage.
[0019] Further, the fourth pump light reflector is used to reflect and couple the pump light generated by the second pump light source into the seventh optical fiber; the second partial reflection film reflects the signal light after double-stage amplification and couples it into the eighth optical fiber.
[0020] Further, the pump light wavelength of the first pump light source is 980 nm.
[0021] Further, the pump light wavelength of the second pump light source is 940 nm.
[0022] The beneficial effects of the present utility model are as follows: In the double-stage amplifier, the first-stage pump ensures high gain and low noise under the high population inversion state, and the second-stage pump is mainly used to increase the output power; the isolator reduces the influence of the backward ASE in the second-stage amplification part on the signal light; the transfer of the pump light and signal light energy is realized in the first active optical fiber; the isolator can prevent the backward light from affecting the EDF and the signal light, and the integrated structure can miniaturize the laser. Description of the Drawings
[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present utility model, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0024] Figure 1 It is a schematic structural diagram of the present utility model;
[0025] Figure 2 It is a schematic diagram of another embodiment of the structure of the present utility model;
[0026] Description of reference numerals in the drawings: 10, first component; 110, first double fiber optic head; 111, first optical fiber; 112, second optical fiber; 120, first birefringent crystal; 130, first wave plate; 140, first lens; 150, first pump light reflecting sheet; 160, first optical rotation crystal; 170, first partial reflection film; 180, first photodiode; 20, first active optical fiber; 30, second component; 310, second double fiber optic head; 311, third optical fiber; 312, fourth optical fiber; 320, second lens; 330, second pump light reflecting sheet; 340, narrowband filter; 350, isolator; 360, third pump light reflecting sheet; 370, third lens; 380, single fiber optic head; 381, fifth optical fiber; 382, third double fiber optic head; 390, first pump light source; 40, second active optical fiber; 50, third component; 510, triple fiber optic head; 511, sixth optical fiber; 512, seventh optical fiber; 513, eighth optical fiber; 520, second birefringent crystal; 530, second wave plate; 540, fourth lens; 550, fourth pump light reflecting sheet; 560, second optical rotation crystal; 570, second partial reflection film; 580, second photodiode; 590, second pump light source. Detailed implementation manners
[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts fall within the protection scope of the present utility model. Therefore, the following detailed description of the embodiments of the present utility model provided in the drawings is not intended to limit the scope of the present utility model to be protected, but merely represents the selected embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without making creative efforts fall within the protection scope of the present utility model.
[0028] In the description of the present utility model, it should be noted that the orientation or positional relationships indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.
[0029] In the description of the present utility model, it should be noted that unless otherwise clearly defined and limited, terms such as "installation", "provided with", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.
[0030] As Figure 1 shown, a low-noise high-power two-stage amplifier includes a first component 10, a first active optical fiber 20, a second component 30, a second active optical fiber 40, and a third component 50 arranged in sequence along the optical path direction; the first component 10 is used to access the signal light and couple the signal light into the first active optical fiber 20; a first pump light source 390 is provided between the first component 10 and the second component 30; the pump light generated by the first pump light source 390 is isolated in the first active optical fiber 20 by the first component 10 and the second component 30; the second component 30 includes a narrowband filter 340 for filtering; the narrowband filter 340 can be used to eliminate the reverse ASE stray light and the local oscillator stray light of the active optical fiber; therefore, isolator 350 components are integrated in the first component 10 and the second component 30 to realize the isolation of the pump light; the output end of the second component 30 is connected to the second active optical fiber 40; a second pump light source 590 is provided between the second component 30 and the third component 50; the pump light generated by the second pump light source 590 is isolated in the second active optical fiber 40 by the second component 30 and the third component 50; isolator 350 components are integrated in the second component 30 and the third component 50 to realize the isolation of the pump light; the signal light is amplified in the first active optical fiber 20 and the second active optical fiber 40 and then output from the third component 50; the first-stage pump ensures high gain and low noise in the high population inversion state, and the second-stage pump is mainly used to improve the output power; the influence of the reverse ASE of the second-stage amplification part is reduced by the action of the isolator 350 in the second component 30.
[0031] In an embodiment of the present utility model, the first component 10 includes a first double fiber optic head 110, a first birefringent crystal 120, a first wave plate 130, a first lens 140, a first pump light reflection sheet 150, a first optical rotation crystal 160, a first partial reflection film 170, and a first photodiode 180 arranged along the optical path direction; the first photodiode 180 is used to detect and monitor the signal light partially transmitted through the first partial reflection film 170; the first pump light reflection sheet 150 acts as an isolator 350 to isolate the pump light in the first active fiber 20; the first component 10 as a whole constitutes another isolator 350, which can block the reflected signal light and ASE light transmitted backward in the laser. Since the input signal light is usually emitted by a seed source, this structure can also prevent the seed light source from being broken down by the backward light;
[0032] The first double fiber optic head 110 includes a first optical fiber 111 and a second optical fiber 112; the signal light is coupled into the first optical fiber 111; the signal light is coupled into the first optical fiber 111; the wavelength of the signal light is usually 1550 nm, and the second optical fiber 112 is the output end and is connected to the first active fiber 20; the first partial reflection film 170 reflects the signal light and couples it into the second optical fiber 112; the first pump light source 390 is connected to the second component 30, so as to realize backward pumping; the first pump light reflection sheet 150 reflects the pump light backward pumped by the first pump light source 390 back into the second optical fiber 112 to improve the utilization rate of the pump light; the first optical fiber 111, the second optical fiber 112, the first lens 140, and the first partial reflector constitute a beam splitter, and part of the signal light is detected by the first photodiode 180. The first component 10 realizes the combination of multiple functions, has a high integration degree, and is beneficial to the miniaturization requirements of the product;
[0033] In an embodiment of the present utility model, the second component 30 includes a second double fiber optic head 310, a second lens 320, a second pump light reflecting sheet 330, a narrowband filter 340, an isolator 350, a third pump light reflecting sheet 360, a third lens 370, and a single fiber optic head 380 arranged along the optical path direction; the second double fiber optic head 310 includes a third optical fiber 311 and a fourth optical fiber 312; the third optical fiber 311 is connected to the first active optical fiber 20 and is used for inputting the signal light after primary amplification and the backward-transmitted pump light; the fourth optical fiber 312 is connected to the first pump light source 390 and is used for inputting the pump light; the second pump light reflecting sheet 330 is used for reflecting and coupling the pump light generated by the first pump light source 390 into the first active optical fiber 20; the third optical fiber 311, the fourth optical fiber 312, the second lens 320, and the second pump light reflecting sheet 330 constitute a beam combiner, realizing the beam combination of the pump source and the signal light, and realizing the energy transfer of the pump light and the signal light in the first active optical fiber 20. At the same time, due to the action of the second pump light reflecting sheet 330, the signal light after primary amplification continues to propagate forward at the second pump light reflecting sheet 330, and further passes through the narrowband filter 340 and the isolator 350. The isolator 350 can prevent the backward light from affecting the EDF and the signal light;
[0034] The second pump light source 590 is connected to the third component 50. The third pump light reflecting sheet 360 is used for reflecting and coupling the pump light generated by the second pump light source 590 into the second active optical fiber 40 to improve the utilization rate of the pump light; the single fiber optic head 380 includes a fifth optical fiber 381. The fifth optical fiber 381 has no output end and is connected to the second active optical fiber 40;
[0035] In an embodiment, as Figure 2 shown, the second pump light source 590 can be connected to the second component 30. By using forward pumping, the amplification of the signal light can be realized. It is only necessary to replace the single fiber optic head 380 in the previous embodiment with a third double fiber optic head 382. After connecting the second pump light source 590, the third pump light reflecting sheet 360 can also isolate the pump light generated by the second pump light source 590 in the second active optical fiber 40; correspondingly, the three-fiber optic head 510 can be replaced with a double fiber optic head including a seventh optical fiber 512 and an eighth optical fiber 513. The 940 nm pump light of forward pumping will also be reflected by the fourth pump light reflecting sheet 550 back into the second active optical fiber 40;
[0036] In one embodiment, the third component 50 includes a triple fiber head 510, a second birefringent crystal 520, a second wave plate 530, a fourth lens 540, a fourth pump light reflector 550, a second optical rotation crystal 560, a second partial reflection film 570, and a second photodiode 580, which are arranged along the optical path direction; the triple fiber head 510 includes a sixth optical fiber 511, a seventh optical fiber 512, and an eighth optical fiber 513; the sixth optical fiber 511 is connected to the second pump light source 590 for inputting pump light; the seventh optical fiber 512 is connected to the second active optical fiber 40; the eighth optical fiber 513 is an output end for outputting the signal light after double-stage amplification; the fourth pump light reflector 550 is used to reflect and couple the pump light generated by the second pump light source 590 into the seventh optical fiber 512; the second partial reflection film 570 reflects the signal light after double-stage amplification and couples it into the eighth optical fiber 513; a part of the signal light after double-stage amplification is transmitted through the second partial reflection film 570 to be detected and monitored by the second photodiode 580; similar to the first component 10, the third component 50 also integrally realizes the beam combination and splitting of the pump light and the signal light, while taking into account the monitoring of the signal, and cooperates with the second component 30 to achieve the effect of isolating the pump light in the second active optical fiber 40;
[0037] In one embodiment, the pump light wavelength of the first pump light source 390 is 980 nm, and the pump light wavelength of the second pump light source 590 is 940 nm. For the first-stage amplification of the signal light, 980-nm single-mode pump is used in cooperation with the first active optical fiber 20 to ensure low noise; for the second-stage amplification, 940-nm multimode pump is used in cooperation with the second active optical fiber 40 to achieve high-power output; the first component 10 can achieve the isolation and power monitoring of the 1550-nm signal light, and realize the return of the 980-nm pump light along the original path; the second component 30 realizes the reverse pumping of the 980-nm pump light, the signal light passes through in the forward direction, narrowband filtering and noise reduction are performed, and the return of the 940-nm pump light along the original path is realized; the third component 50 realizes the reverse pumping of the 940-nm pump light, and realizes the isolation and power monitoring of the 1550-nm signal light; the assembly structures of the first component 10, the second component 30, and the third component 50 are simple, and each component realizes the integration of multiple functions, which is beneficial to the miniaturization of the double-stage amplifier, and the noise can be effectively filtered in the optical path structure, and the output power can be improved.
[0038] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent transformation made by using the specification and drawings of the present invention, or directly or indirectly applied in the related technical fields, shall be included in the patent protection scope of the present invention by the same token.
Claims
1. A low-noise high-power two-stage amplifier, characterized in that: It includes a first component (10), a first active optical fiber (20), a second component (30), a second active optical fiber (40), and a third component (50) arranged in sequence along the optical path direction; the first component (10) is used to access the signal light and couple the signal light into the first active optical fiber (20); a first pump light source (390) is provided between the first component (10) and the second component (30); the pump light generated by the first pump light source (390) is isolated in the first active optical fiber (20) by the first component (10) and the second component (30); the second component (30) includes a narrowband filter (340) for filtering; the output end of the second component (30) is connected to the second active optical fiber (40); a second pump light source (590) is provided between the second component (30) and the third component (50); the pump light generated by the second pump light source (590) is isolated in the second active optical fiber (40) by the second component (30) and the third component (50); the signal light is amplified in the first active optical fiber (20) and the second active optical fiber (40) and then output from the third component (50).
2. The low-noise high-power two-stage amplifier according to claim 1, wherein: The first component (10) includes a first double fiber head (110), a first birefringent crystal (120), a first wave plate (130), a first lens (140), a first pump light reflecting sheet (150), a first optical rotation crystal (160), a first partial reflection film (170), and a first photodiode (180) arranged along the optical path direction; the first photodiode (180) is used to detect and monitor the signal light that partially transmits through the first partial reflection film (170).
3. The low-noise high-power two-stage amplifier according to claim 2, characterized in that: The first double fiber head (110) includes a first optical fiber (111) and a second optical fiber (112); the signal light is coupled into the first optical fiber (111); the wavelength of the signal light is 1550 nm; the second optical fiber (112) is the output end and is connected to the first active optical fiber (20); the first partial reflection film (170) reflects the signal light and couples it into the second optical fiber (112); the first pump light source (390) is connected to the second component (30), and the first pump light reflecting sheet (150) reflects the pump light backward pumped by the first pump light source (390) back into the second optical fiber (112) to improve the utilization rate of the pump light.
4. A low-noise high-power two-stage amplifier according to claim 1, characterized in that: The second component (30) includes a second dual fiber optic head (310), a second lens (320), a second pump light reflecting sheet (330), a narrowband filter (340), an isolator (350), a third pump light reflecting sheet (360), a third lens (370), and a single fiber optic head (380) arranged along the optical path direction; the first pump light source (390) is connected to the second component (30), and the second pump light reflecting sheet (330) is used to reflect and couple the pump light generated by the first pump light source (390) into the first active optical fiber (20); the second pump light source (590) is connected to the third component (50), and the third pump light reflecting sheet (360) is used to reflect and couple the pump light generated by the second pump light source (590) into the second active optical fiber (40) to improve the utilization rate of the pump light.
5. A low-noise high-power two-stage amplifier according to claim 4, characterized in that: The second dual fiber optic head (310) includes a third optical fiber (311) and a fourth optical fiber (312); the third optical fiber (311) is connected to the first active optical fiber (20) and is used to input the signal light after primary amplification. The fourth optical fiber (312) is connected to the first pump light source (390) and is used to input the pump light; the single fiber optic head (380) includes a fifth optical fiber (381); the fifth optical fiber (381) is the output end and is connected to the second active optical fiber (40).
6. A low-noise high-power two-stage amplifier according to claim 1, characterized in that: The third component (50) includes a triple fiber optic head (510), a second birefringent crystal (520), a second wave plate (530), a fourth lens (540), a fourth pump light reflecting sheet (550), a second optically active crystal (560), a second partial reflection film (570), and a second photodiode (580) arranged along the optical path direction; the second photodiode (580) is used to detect and monitor the signal light after double-stage amplification that partially transmits through the second partial reflection film (570).
7. A low-noise high-power two-stage amplifier according to claim 6, characterized in that: The triple fiber optic head (510) includes a sixth optical fiber (511), a seventh optical fiber (512), and an eighth optical fiber (513); the sixth optical fiber (511) is connected to the second pump light source (590) and is used to input the pump light; the seventh optical fiber (512) is connected to the second active optical fiber (40); the eighth optical fiber (513) is the output end and is used to output the signal light after double-stage amplification.
8. A low-noise high-power two-stage amplifier according to claim 7, characterized in that: The fourth pump light reflecting sheet (550) is used to reflect and couple the pump light generated by the second pump light source (590) into the seventh optical fiber (512); the second partial reflection film (570) reflects the signal light after double-stage amplification and couples it into the eighth optical fiber (513).
9. A low-noise high-power two-stage amplifier according to claim 1, characterized in that: The pump light wavelength of the first pump light source (390) is 980 nm.
10. A low-noise high-power two-stage amplifier according to claim 1, characterized in that: The pump light wavelength of the second pump light source (590) is 940 nm.