An optical amplifier and related apparatus

Abstract

Embodiments of the present application provide an optical amplifier and related equipment for reducing the NF of the optical amplifier and improving the signal transmission quality. The optical amplifier provided by the embodiments of the present application comprises n-stage gain media arranged in sequence, and the n-stage gain media are used to amplify the input optical signal of an optical module in sequence. n≥2. The optical signal is input from the first-stage gain medium in the n-stage gain media and output from the n-stage gain medium in the n-stage gain media. The n-stage gain media comprise a first gain medium and a second gain medium, the first gain medium is an m-stage gain medium in the n-stage gain media, the second gain medium is at least one gain medium behind the first gain medium, the first gain medium and the second gain medium are different types of gain media, and the output end of the first gain medium is connected with the input end of the second gain medium. The average gain of the type of gain medium to which the first gain medium belongs is greater than the average gain of the type of gain medium to which the second gain medium belongs.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of optical communication, and in particular to an optical amplifier and related equipment. BACKGROUND

[0002] An optical amplifier (OA) is a commonly used device in an optical communication network, used to amplify the power of an optical signal. With the development of optical communication networks, the power requirements for optical signals are becoming higher and higher, and the gain requirements for optical amplifiers are also becoming higher and higher.

[0003] A commonly used method to improve the gain of an optical amplifier is to cascade multiple gain media, and to amplify the optical signal step by step through multiple stages of gain media, thereby achieving high gain for the optical signal.

[0004] Gain media have inherent noise factors (NFs). In a cascaded optical amplifier structure, the NFs of the gain media at each stage contribute to the overall NF of the optical amplifier, resulting in a large overall NF of the optical amplifier, which leads to a low signal-to-noise ratio of the optical amplifier and affects the quality of signal transmission. SUMMARY

[0005] Embodiments of the present application provide an optical amplifier and related equipment for reducing the NF of the optical amplifier and improving the quality of signal transmission.

[0006] In a first aspect, embodiments of the present application provide an optical amplifier. The optical amplifier includes n stages of gain media arranged in sequence, and the n stages of gain media are configured to sequentially amplify an input optical signal of the optical amplifier. Wherein n≥2. The optical signal is input from a first stage of gain media in the n stages of gain media and output from an nth stage of gain media in the n stages of gain media. The n stages of gain media include a first gain medium and a second gain medium, the first gain medium is an mth stage of gain medium in the n stages of gain media, and the second gain medium is at least one gain medium after the first gain medium. Wherein, That is, m is less than or equal to the result of rounding up (n / 2). The first gain medium and the second gain medium are different types of gain media. An output end of the first gain medium is connected to an input end of the second gain medium. The average gain of the type of gain medium to which the first gain medium belongs is greater than the average gain of the type of gain medium to which the second gain medium belongs. In embodiments of the present application, the average gain is the average gain of the gain medium for signals in the operating wavelength band.

[0007] In embodiments of the present application, in the optical amplifier structure of multiple stages of gain media, the NFs of the first half of the gain media have a greater contribution to the overall NF of the optical amplifier, and the NF of a gain medium is negatively correlated with the average gain of the type of gain medium to which the gain medium belongs. Therefore, the first half of the gain media are made to be of a type with a smaller average gain, and the second half of the gain media are made to be of a type with a larger average gain, so that the overall NF of the optical amplifier is reduced. The average gain of the first gain medium (of the gain medium type, hereinafter referred to as the type) in the stage is greater than the average gain of the second gain medium (of the type) in the subsequent stage, which can minimize the NF of the optical amplifier, improve the signal-to-noise ratio of the optical amplifier, and improve the signal transmission quality.

[0008] In an optional implementation, the maximum average gain of the gain medium type of the first gain medium is greater than the maximum average gain of the gain medium type of the second gain medium.

[0009] In the embodiments of the present application, the maximum average gain is the average gain of the gain medium for each wavelength signal in the working wavelength band (of the optical amplifier) at the optimal medium length, and the optimal medium length is the medium length corresponding to the maximum gain at different medium lengths.

[0010] In the embodiments of the present application, the maximum average gain of the gain medium type is a representation of the average gain of the gain medium type. Compared with the average gain, the maximum average gain can more accurately reflect the type of the gain medium, thereby more accurately distinguishing the first gain medium and the second gain medium.

[0011] It is worth noting that in other implementations below, the maximum average gain can also be used to better distinguish the gain media of different types, which will not be described below.

[0012] In an optional implementation, m≥2, and the n-stage gain media arranged in sequence include the first-stage gain medium to the m-stage gain medium connected in sequence. In the first-stage gain medium to the m-stage gain medium connected in sequence, the average gain of the gain medium type of each stage is greater than the average gain of the gain medium type of the second gain medium.

[0013] In the embodiments of the present application, the average gain of the first m-stage gain medium (of the type) is greater than the average gain of the second gain medium (of the type) in the subsequent stage, which can ensure that the NF of the gain medium in the front stage is small. Since the weight of the first m-stage gain medium is greater than the weight of the second gain medium in the subsequent stage, the structure can make the NF of the gain medium with a large weight relatively small, thereby reducing the noise factor NF of the optical amplifier oa , and improving the signal transmission quality.

[0014] It is worth noting that the first-stage gain medium to the m-stage gain medium connected in sequence can be gain media of the same type or gain media of different types, which is not limited in the present application.

[0015] In an optional implementation, m≤n / 3.

[0016] In the embodiments of the present application, since the first third gain medium is the earlier gain medium in the n-stage gain medium, the first third gain medium has a larger weight in the noise figure NF oa . By limiting the first gain medium to the first third gain medium, the noise figure NF oa can be more significantly reduced, and the signal transmission quality is improved.

[0017] In an optional implementation, m=1. If the number of the second gain media is 1, the output end of the first gain medium is connected to the input end of the second gain medium; if the number of the second gain media is greater than 1, the output end of the first gain medium is connected to the input end of the first-stage gain medium in the plurality of second gain media.

[0018] In the embodiments of the present application, since the first-stage gain medium has the largest weight in the noise figure NF oa in the n-stage gain medium, the first gain medium is limited to the first-stage gain medium, and compared with being arranged at other positions, the best optimization effect of the noise figure NF oa can be achieved, thereby improving the signal transmission quality.

[0019] In an optional implementation, in the n-stage gain media arranged in sequence, the average gain of the category to which any gain medium belongs is greater than the average gain of the category to which the next-stage gain medium belongs. That is, in the n-stage gain medium 2000, the average gain of the category to which the gain medium belongs gradually decreases from the first-stage gain medium to the n-stage gain medium.

[0020] In the embodiments of the present application, since the average gain of the gain medium is negatively correlated with the NF, the average gain of the n-stage gain medium gradually decreases, and the NF of the n-stage gain medium gradually increases. Since the weight of each stage in the n-stage gain medium gradually decreases (the earlier the gain medium, the greater the weight of the noise figure NF oa ), the weight of the gain medium with a greater weight is smaller, the noise figure NF oa can be more significantly reduced, and the signal transmission quality is improved.

[0021] In an optional implementation, m>2, and the n-stage gain medium further includes a third gain medium, the third gain medium is a k-stage gain medium in the n-stage gain medium, and k

[0022] In an optional implementation, m=2, and k=1.

[0023] In an optional implementation, the n-stage gain medium further comprises a fourth gain medium, an input end of the fourth gain medium is connected with an output end of the second gain medium, and the fourth gain medium is a different kind of gain medium from the second gain medium. The average gain of the kind of gain medium to which the fourth gain medium belongs is greater than the average gain of the kind of gain medium to which the second gain medium belongs.

[0024] In an optional implementation, at least one target gain medium exists in the second gain medium, and the gain flatness of the target gain medium is better than the gain flatness of the first gain medium. The target gain medium is at least one gain medium behind the m-stage gain medium.

[0025] In the same stage of gain medium, the average gain and the gain flatness cannot be optimized at the same time, and a trade-off needs to be made between the two in application. Since the target gain medium is relatively later in the n-stage gain medium, the weight of the target gain medium is smaller. If the average gain of the target gain medium is increased to reduce the noise figure NF of the optical amplifier oa oa , the benefit is small and insignificant. Therefore, the gain flatness of the target gain medium is made better (better than the gain flatness of the first gain medium 2100), which can improve the spectral flatness of the optical amplifier oa, thereby reducing the GFF depth, reducing the loss of the optical amplifier oa, and further reducing the pump power of the pump module corresponding to each stage of gain medium.

[0026] In an optional implementation, the gain flatness of at least one gain medium in the second gain medium is better than the gain flatness of the first gain medium.

[0027] In the embodiments of the present application, the first gain medium is mainly used to reduce the noise figure NF of the optical amplifier oa oa . The second gain medium behind the first gain medium has a smaller impact on the noise figure NF of the optical amplifier oa oa . Therefore, the gain flatness of all the second gain medium behind the first gain medium is better than the gain flatness of the first gain medium. The gain flatness of the optical amplifier oa is improved by all the second gain medium, thereby more significantly reducing the GFF depth, reducing the loss of the optical amplifier oa, and reducing the pump power.

[0028] In an optional implementation, in the n-stage gain medium arranged in sequence, the gain flatness of any gain medium is better than the gain flatness of the gain medium in the previous stage.

[0029] In the embodiments of the present application, since the average gain and the gain flatness of the gain medium cannot be optimal at the same time, the gain flatness of the n-stage gain medium is gradually improved, that is, in the trade-off between the average gain and the gain flatness, the gain medium at the front is more inclined to the average gain, and the gain medium at the back is more inclined to the gain flatness. From the foregoing description of the weight of the noise figure NF oa of each stage of the gain medium, it can be known that the weight of each stage of the n-stage gain medium gradually decreases (the gain medium at the front has a greater weight of the noise figure NF oa ). The gain medium at the front is more inclined to the average gain, and the noise figure NF oa of the optical amplifier oa can be better reduced; the gain medium at the back is more inclined to the gain flatness, and the loss of the optical amplifier oa can be better reduced, so that the optical amplifier oa has a lower noise figure NF oa and a smaller loss.

[0030] In an optional implementation, the n-stage gain medium arranged in sequence includes multiple gain media of different types.

[0031] In an optional implementation, the number of the second gain media is multiple, and the multiple second gain media include multiple gain media of different types.

[0032] In an optional implementation, the multiple gain media of different types include at least one of the following: doped optical fibers with different doping elements, doped optical fibers with different doping concentrations, and gain media with different structures.

[0033] In an optional implementation, between the output end of the first gain medium and the input end of the second gain medium, a gain flatness filter GFF and / or a variable optical attenuator VOA are further included, the GFF is used to balance the gain of the optical signal at each wavelength, and the VOA is used to adjust the gain point and the inclination of the optical amplifier.

[0034] In an optional implementation, the optical amplifier further includes a control circuit. The control circuit is used to control at least one of the following of the output optical signal of the optical amplifier: output optical power, gain, and inclination.

[0035] In a second aspect, the embodiments of the present application provide an optical communication device. The optical communication device includes the optical amplifier of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A structural schematic diagram of an optical communication system provided by the present application is shown;

[0037] Figure 2 A structural schematic diagram of an optical amplifier oa provided by the embodiments of the present application is shown;

[0038] Figure 3 A gain medium provided by the embodiment of the present application provides a gain diagram of different medium lengths;

[0039] Figure 4 A structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which the maximum average gain decreases step by step;

[0040] Figure 5a A structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which the first gain medium front stage includes a low gain medium;

[0041] Figure 5b Another structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which the first gain medium front stage includes a low gain medium;

[0042] Figure 6 A structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which the third gain medium is included;

[0043] Figure 7 A structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which the fourth gain medium is included;

[0044] Figure 8 A gain flatness arrangement diagram of an optical amplifier oa provided by the embodiment of the present application;

[0045] Figure 9 A wavelength-gain curve diagram provided by the embodiment of the present application;

[0046] Figure 10 A structure diagram of an optical amplifier oa provided by the embodiment of the present application, in which different kinds of second gain media are included. DETAILED DESCRIPTION

[0047] The embodiments of the present application are described below with reference to the accompanying drawings. It is known to those skilled in the art that the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems as the technology develops and new scenarios appear.

[0048] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to those processes, methods, products, or apparatuses. Additionally, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can be expressed as: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0049] Figure 1 This is a schematic diagram of an optical communication system. An optical communication system includes a transmitting device, a receiving device, and optical fibers. The transmitting device performs electro-optical modulation to carry the signal in the optical fiber and transmits the optical signal through the optical fiber. The optical fiber is used to transmit the optical signal. The receiving device receives and interprets the optical signal.

[0050] like Figure 1 As shown, an optical communication system may also include an optical amplifier. The optical amplifier is located between the transmitting and receiving devices. The optical amplifier is used to amplify the optical signal, thereby increasing the power of the optical signal at the receiving device. This compensates for signal loss and improves the reliability and quality of signal transmission.

[0051] Optionally, optical amplifiers can also exist in any optical communication device (such as transmitting device, receiving device, relay node, etc.) in the optical communication system to amplify optical signals.

[0052] With the development of optical communication technology, the requirements for transmission power in optical communication systems are becoming increasingly higher, as are the requirements for the output power of optical amplifiers. To increase the output power of optical amplifiers, it is necessary to increase their gain. A common method is to cascade multiple gain media within the optical amplifier. By amplifying the optical signal stage by stage through multiple gain media, high gain of the optical signal is achieved, thereby increasing the output power of the optical amplifier.

[0053] However, the gain medium itself has an inherent noise figure (NF). In a multi-stage gain medium optical amplifier structure, the NF of each stage of the gain medium contributes to the NF of the optical amplifier, resulting in a large NF. A large NF leads to a low optical signal-to-noise ratio (OSNR) of the optical amplifier, affecting the signal transmission quality.

[0054] To address the aforementioned problems, embodiments of this application provide an optical amplifier and related devices. The optical amplifier provided in this application improves signal transmission quality by placing the gain medium with the higher average gain in a more prominent position within a multi-stage gain medium, thereby reducing the NF (noise refractory frequency) of the optical amplifier.

[0055] The optical amplifier OA provided in this embodiment includes n stages of gain media 2000 arranged sequentially, and the noise figure NF of the optical amplifier OA is... oa The theoretical calculation formula is shown in Formula 1 below:

[0056]

[0057] Among them, NF x G represents the noise figure of the x-th gain medium. x Let L be the gain of the x-th level gain medium, which is the actual gain of the gain medium; x This represents the loss value between the (x-1)th level gain medium and the xth level gain medium.

[0058] In Formula 1, the n terms represent the noise figures generated by each gain medium in the n-stage gain medium. The sum of the n noise figures is the noise figure NF of the optical amplifier oa. oa If we compare the noise figure generated by each gain medium in the optical amplifier OA in Formula 1 with the noise figure NF of that gain medium itself... x Dividing by this gives the weight of that gain medium in the optical amplifier OA. A larger weight indicates a higher noise figure (NF) of that gain medium in the optical amplifier OA. x The greater the contribution, the better. Because compared to L... x G x It is usually quite large, so G is the main consideration. x The impact on the weight size.

[0059] In Formula 1, the noise figure generated by the first-stage gain medium is the first term NF1, and the ratio of NF1 to the noise figure NF1 of the first-stage gain medium is 1, that is, the weight of the first-stage gain medium is 1.

[0060] In Formula 1, the noise figure generated by the second-stage gain medium is the second term. The ratio of the noise figure NF2 of the second-stage gain medium is approximately That is, the weight of the second-stage gain medium is Weight of the second-stage gain medium The weight is less than 1 for the first-stage gain medium.

[0061] In Formula 1, the noise figure generated by the third-stage gain medium is the third term. The ratio of the noise figure NF3 of the third-stage gain medium is approximately That is, the weight of the third-stage gain medium is Weight of the third-stage gain medium Weight less than the second-stage gain medium

[0062] Following this logic, it can be seen that the weight of the gain medium decreases as the stage progresses. In other words, the noise figure NF of the gain medium in the first few stages of the optical amplifier OA has a significant impact on the OA. Furthermore, the noise figure NF of the gain medium in the earlier stages has a greater impact on the OA. Therefore, reducing the noise figure NF of the gain medium in the earlier stages will reduce the noise figure NF of the optical amplifier OA. oa .

[0063] Therefore, in this embodiment, the noise figure NF of the optical amplifier oa is reduced. oa The approach is to ensure that the noise figure of the first few gain media stages in the n-stage gain amplifier is less than the noise figure NF of the later stages. Since the noise figure NF of the gain media is negatively correlated with the average gain of the type of gain media (hereinafter referred to as the average gain of the gain media for convenience), making the average gain of the first few gain media stages in the optical amplifier OA greater than the average gain of the later stages reduces the NF of the first few stages, thereby reducing the noise figure NF of the optical amplifier OA. oa .

[0064] Therefore, the embodiments of this application provide Figure 2 The optical amplifier structure shown is such that the average gain of the m-th stage gain medium (first gain medium 2100) in the optical amplifier OA is greater than the average gain of the second gain medium 2200 in the stage following the first gain medium 2100. This reduces the noise factor (NF) of the m-th stage gain medium, thereby reducing the noise figure (NF) of the optical amplifier OA.oa .

[0065] As shown in Figure 2 , the optical amplifier (oa) provided by the embodiment of the present application comprises n-stage gain media 2000 arranged in sequence. Wherein, n≥2. The optical signal is input from the first-stage gain medium in the n-stage gain media 2000, and is output from the nth-stage gain medium in the n-stage gain media 2000. The n-stage gain media 2000 is used to amplify the input optical signal of the optical amplifier oa in sequence.

[0066] The n-stage gain media 2000 comprises a first gain medium 2100 and a second gain medium 2200. The first gain medium 2100 and the second gain medium 2200 are different kinds of gain media. The average gain of the kind of gain medium to which the first gain medium 2100 belongs is greater than the average gain of the kind of gain medium to which the second gain medium 2200 belongs. For example, the first gain medium 2100 is a semiconductor optical amplifier (SOA), and the second gain medium 2200 is an erbium-doped fiber (EDF).

[0067] The first gain medium 2100 is the mth-stage gain medium in the n-stage gain media 2000, and the second gain medium 2200 is at least one gain medium behind the first gain medium 2100. The output end of the first gain medium 2100 is connected with the input end of the second gain medium 2200.

[0068] In the embodiment of the present application, the first gain medium 2100 is the mth-stage gain medium in the n-stage gain media 2000. In the n-stage gain media 2000, the earlier the first gain medium 2100 is (i.e. the smaller m is), the smaller the noise figure NF oa of the optical amplifier oa is, and the better the transmission quality of the signal is.

[0069] In order to realize a smaller noise figure NF oa , the value range of m can be limited to , that is, m is less than or equal to the result of rounding up (n / 2), so as to limit the first gain medium 2100 in the first half of the n-stage gain media 2000.

[0070] That is, in the n-stage gain media 2000, the first gain medium 2100 exists in the first 1 / 2-stage gain media. There is at least one second gain medium 2200 behind the first gain medium 2100, and the average gain of the kind of gain medium to which the second gain medium 2200 belongs is smaller than the average gain of the kind of gain medium to which the first gain medium 2100 belongs.

[0071] For exampleFigure 2 n = 3, then m can be 1 or 2. The first gain medium 2100 is the first or second gain medium in the three-stage gain medium 2000. Figure 2 Taking the first-stage gain medium as an example of the first gain medium 2100, the second and third gain media are the second gain medium 2200.

[0072] In the embodiments of the present application, the average gain is an inherent property of the gain medium and is related to the type of the gain medium. The average gain of the gain medium is the average gain of the gain medium to each wavelength signal in the working wavelength band of the optical amplifier oa.

[0073] It is worth noting that the average gain of the type of the gain medium is an inherent property of the type of the gain medium. However, in the optical amplifier oa, the actual gain of the first gain medium 2100 can be greater or smaller than the actual gain of the second gain medium 2200, which is not limited in the present application. In one example, the gain of the first gain medium 2100 is 3 dB, and the gain of the second gain medium 2200 is 4 dB.

[0074] In the embodiments of the present application, in the multi-stage gain medium optical amplifier structure, the NF of the first half of the gain media has a greater contribution to the overall NF of the optical amplifier, and the NF of the gain medium is negatively related to the average gain of the type of the gain medium. Therefore, the average gain of the first gain medium 2100 of the mth stage in the n-stage gain medium 2000 (the type of the gain medium, hereinafter referred to as the type) is greater than the average gain of the second gain medium (the type) of the later stage, which can maximize the NF of the optical amplifier, improve the signal-to-noise ratio of the optical amplifier, and improve the signal transmission quality.

[0075] The maximum average gain of the type of the gain medium is a representation of the average gain of the type of the gain medium. The maximum average gain is also an inherent property of the gain medium and is related to the type of the gain medium. For each type of gain medium, the gain of the gain medium is related to the length of the medium, and an example of the corresponding medium length-gain curve is shown in FIG. 3. Figure 3 In the medium length-gain curve, the medium length corresponding to the maximum gain is the optimal medium length of the type of the gain medium. The average gain of the type of the gain medium to each wavelength signal in the working wavelength band of the optical amplifier oa is the maximum average gain of the type of the gain medium.

[0076] In an alternative implementation, the maximum average gain of the type of the gain medium to which the first gain medium 2100 belongs can be greater than the maximum average gain of the type of the gain medium to which the second gain medium 2200 belongs.

[0077] In the embodiments of the present application, the maximum average gain of the gain medium belongs to the category of the average gain of the gain medium. Compared with the average gain, the maximum average gain can more accurately reflect the category of the gain medium, thereby more accurately distinguishing the first gain medium and the second gain medium.

[0078] It is worth noting that in other embodiments below, the maximum average gain can also be used to better distinguish different categories of gain media, which will not be described below.

[0079] In the embodiments of the present application, the optical amplifier oa can also include a pumping module of each stage of gain medium 2000, and the pumping module is used to output pumping to the corresponding gain medium. For example Figure 2 In the embodiments of the present application, the first stage gain medium is an erbium-doped optical fiber, and the pumping module of the gain medium is used to emit pumping light, which is output to the first stage gain medium to amplify the optical signal. Optionally, the pumping can be pumping light, pumping current or pumping voltage, etc., which is not limited by the present application.

[0080] Optionally, the value range of m can be further narrowed, so that the first gain medium 2100 is more forward, thereby further reducing the noise figure NF oa of the optical amplifier oa, and improving the signal transmission quality. For example, the value range of m can be limited to m≤n / 3, thereby limiting the first gain medium 2100 to the first third of the n-stage gain medium 2000.

[0081] In the embodiments of the present application, since the first third of the gain medium is the gain medium in the n-stage gain medium 2000, the weight of the noise figure NF oa occupied by the first third of the gain medium is larger, and the first gain medium 2100 is limited to the first third of the gain medium, which can more significantly reduce the noise figure NF oa and improve the signal transmission quality.

[0082] In an optional implementation, m=1, that is, the first gain medium 2100 is the first stage gain medium in the n-stage gain medium 2000. In the embodiments of the present application, since in the n-stage gain medium 2000, the first stage gain medium occupies the largest weight of the noise figure NF oa , therefore, the first gain medium 2100 is limited to the first stage gain medium, which can achieve the best optimization effect on the noise figure NF oa compared to setting the first gain medium 2100 at other positions, thereby improving the signal transmission quality.

[0083] In one optional implementation, among the n sequentially arranged gain media 2000, the average gain of any gain media of a certain type is greater than the average gain of the next-next-level gain media of that type. That is, as... Figure 4 As shown, in the n-stage gain medium 2000, the maximum average gain of the gain medium decreases progressively from the first-stage gain medium to the nth-stage gain medium. Among them, the first-stage gain medium with the largest maximum average gain is the first gain medium 2100, and the other gain media besides the first-stage gain medium are the second gain medium 2200.

[0084] In this embodiment, since the average gain of the gain medium type is negatively correlated with NF, the average gain of the n-level gain medium 2000 decreases step by step, thus achieving a step-by-step increase in NF for the n-level gain medium 2000. This is based on the aforementioned relationship between the noise figure NF of each level of gain medium. oa The weighting explanation shows that the weight of each level in the n-level gain medium 2000 decreases progressively (the earlier the gain medium, the higher its noise figure NF). oa The greater the weight, the smaller the NF of the gain medium. In the n-stage gain medium 2000, the weight of each stage decreases and the NF increases. Therefore, the larger the weight, the smaller the NF of the gain medium, which can better reduce the noise figure NF. oa This improves signal transmission quality.

[0085] Similarly, it is also possible to ensure that the maximum average gain of any one of the multiple second gain media 2200 arranged sequentially is greater than the maximum average gain of the next-stage gain media. That is, the maximum average gain of the multiple second gain media 2200 after the first gain media 2100 decreases progressively.

[0086] Similarly, it is also possible to make the maximum average gain of any type of gain medium in the n-level gain mediums 2000 arranged sequentially greater than the maximum average gain of the type of the next level gain medium.

[0087] In one alternative implementation, m ≥ 2. To minimize the noise figure NF... oa This allows for a larger maximum average gain value in the first few gain media stages. Specifically, in the n-stage gain media 2000, the average gain of the first to m-stage gain media types is greater than the average gain of the second-stage gain media type.

[0088] For example Figure 5a As shown, n=4, m=2, the first gain medium 2100 is the second gain medium, then the third to fourth gain media are all the second gain medium 2200.

[0089] The average gain of the first-stage gain medium is 8dB, the average gain of the second-stage gain medium (the first gain medium 2100) is 10dB, both of which are greater than the average gain of the second gain medium 2200 (the third-stage and fourth-stage gain medium), which is 5dB.

[0090] In the embodiments of the present application, the average gain of the first m-stage gain medium is greater than the average gain of the second gain medium 2200 of the subsequent stage, which can ensure that the NF of the first-stage gain medium is small. Since the weight of the first m-stage gain medium is greater than the weight of the second gain medium 2200 of the subsequent stage, the structure can make the NF of the gain medium with greater weight relatively small, thereby reducing the noise figure NF oa , and improving the signal transmission quality.

[0091] It is worth noting that the first m-stage gain medium can be different types of gain medium, as shown in Figure 5a , so that the average gain of the type to which the first m-stage gain medium belongs is different. Or it can also be as shown in Figure 5b , the first m-stage gain medium is the same type of gain medium (for example, all erbium-doped optical fibers), and the average gain of the type to which the first m-stage gain medium belongs is the same, which is not limited by the present application.

[0092] Similarly, the maximum average gain of the first m-stage gain medium can also be greater than the maximum average gain of the second gain medium 2200 of the subsequent stage.

[0093] In an optional implementation, the first gain medium 2100 further includes a third gain medium 2300 with lower gain in the front stage.

[0094] The third gain medium 2300 is the k-stage gain medium in the n-stage gain medium, and k

[0095] For example, as shown in Figure 6 , n=4, m=2, the first gain medium 2100 is the second-stage gain medium with an average gain of 12dB. The third-stage and fourth-stage gain medium are both the second gain medium 2200 with an average gain of 6dB. The first-stage gain medium is the third gain medium 2300 with an average gain of 6dB, which is less than the average gain of the first gain medium 2100.

[0096] In an optional implementation, the second gain medium 2200 is further followed by a fourth gain medium 2400 with higher gain. The input of the fourth gain medium 2400 is connected to the output of the second gain medium 2200, and the fourth gain medium 2400 is of a different type from the second gain medium 2200. The average gain of the type of the fourth gain medium is greater than the average gain of the type of the second gain medium.

[0097] For example Figure 7 As shown in the figure, n = 4, m = 1, the second and third gain media are the second gain medium 2200, and the maximum average gain is 6 dB. The fourth gain medium is the fourth gain medium 2400, and the average gain is 10 dB, which is greater than the average gain of the second gain medium 2200.

[0098] In the embodiments of the present application, in addition to reducing the noise figure NF of the optical amplifier oa om , the gain flattening filter (GFF) depth of the optical amplifier oa can also be reduced by sorting the gain flatness of each gain medium in the n-stage gain medium 2000, thereby reducing the power consumption of the optical amplifier oa.

[0099] In an optional implementation, at least one second gain medium 2200 following the first gain medium 2100 has a target gain medium, and the gain flatness of the target gain medium is better than the gain flatness of the first gain medium 2100.

[0100] In the embodiments of the present application, the optical amplifier oa can further include a gain flattening filter GFF, a variable optical attenuator (VOA), and the like. The GFF can be located between any two gain media in the n-stage gain medium 2000, and is used to balance the gain of the optical signal at each wavelength. The VOA can be located between any two gain media in the n-stage gain medium 2000, and is used to adjust the gain point and the slope of the optical amplifier oa.

[0101] For example Figure 8 As shown in the figure, n = 3, a GFF is included between the first gain medium (the first gain medium 2100) and the second gain medium, and a GFF and a VOA are included between the second gain medium and the third gain medium.

[0102] After the first-stage gain medium amplifies the input optical signal, it outputs the amplified signal to the GFF. The GFF performs a flattening filter on the signal, making the gain spectrum of the signal flatter. Then, the optical signal is sequentially input into the second-stage gain medium for amplification, input into the GFF for flattening filtering, input into the VOA to adjust the attenuation to match the power adjustment of the pump module (to achieve different gain point locking and tilt adjustment of the optical amplifier), and input into the third-stage gain medium for amplification.

[0103] like Figure 9 As shown, after the optical signal is amplified by the gain medium, the gain varies across different wavelengths due to the gain flatness of the medium. Some wavelength bands have higher gains, while others have lower gains. According to... Figure 9 The wavelength-gain curve shown provides the average gain for each wavelength within the operating band of the optical amplifier OA. The gain flatness is obtained by calculating the envelope area between the minimum gain in the operating band and the wavelength-gain curve.

[0104] GFF (Gas Flattening Filter) achieves signal flattening by attenuating peaks in the gain curve. GFF is a filter spectrum that attenuates the optical signal; the greater the GFF depth, the greater the power attenuation. The worse the gain flatness of the gain medium, the greater the corresponding GFF depth, the greater the power attenuation, and the greater the loss to the optical amplifier (OA), thus requiring a higher power pump from the pump module.

[0105] Within the same gain level medium, maximum average gain and gain flatness are usually not simultaneously optimal; a trade-off must be made between them in applications. Since the target gain medium is located relatively late in the n-level gain medium hierarchy, its weight is relatively small. Therefore, increasing the maximum average gain of the target gain medium can reduce the noise figure NF of the optical amplifier oa. oa The benefit is small and not very meaningful. Therefore, making the gain flatness of the target gain medium better (better than the gain flatness of the first gain medium 2100) can improve the spectral flatness of the optical amplifier oa, thereby reducing the GFF depth, reducing the loss of the optical amplifier oa, and further reducing the pump power of the pump module corresponding to each gain medium.

[0106] In one alternative implementation, the gain flatness of at least one of the second gain media 2200 is better than the gain flatness of the first gain media 2100. For example... Figure 8 As shown, the first-stage gain medium is the first gain medium 2100, and the second and third-stage gain media are the second gain medium 2200, which are also the target gain media. The gain flatness of the second and third-stage gain media is better than that of the first-stage gain medium.

[0107] In this embodiment, the first gain medium 2100 is mainly used to reduce the noise figure NF of the optical amplifier oa.oa The second gain medium behind the first gain medium 2100 has less influence on the noise figure NF of the optical amplifier oa. Therefore, the gain flatness of all the second gain media 2200 behind the first gain medium 2100 is better than the gain flatness of the first gain medium 2100. The gain flatness of the optical amplifier oa is improved by all the second gain media 2200, so that the GFF depth is more significantly reduced, the loss of the optical amplifier oa is reduced, and the pump power is reduced. oa oa oa

[0108] In an optional implementation, in the n-stage gain media 2000 arranged in sequence, the gain flatness of any gain medium is better than the gain flatness of the gain medium in the previous stage. That is, the gain flatness of the n-stage gain media 2000 is better and better, for example, as shown in FIG. 2B. Figure 8

[0109] In the embodiments of the present application, because the maximum average gain and the gain flatness of the gain medium cannot be optimal at the same time, the gain flatness of the n-stage gain media 2000 is better and better, that is, in the trade-off between the maximum average gain and the gain flatness, the gain medium in the earlier stage is more inclined to the maximum average gain, and the gain medium in the later stage is more inclined to the gain flatness. From the foregoing description of the weight of the noise figure NF occupied by each stage of gain medium, it can be known that the weight of each stage of the n-stage gain media 2000 is gradually reduced (the weight of the noise figure NF occupied by the gain medium in the earlier stage is greater). The gain medium in the earlier stage is more inclined to the maximum average gain, which can better reduce the noise figure NF of the optical amplifier oa; the gain medium in the later stage is more inclined to the gain flatness, which can better reduce the loss of the optical amplifier oa, so that the optical amplifier oa has both a lower noise figure NF and a smaller loss. oa oa

[0110] It is worth noting that Figure 8 the foregoing is only an example of the positions of the GFF and the VOA, and does not limit the number and positions of the GFF and the VOA. The optical amplifier oa can include more or fewer GFFs and more or fewer VOA, which are not limited in the present application.

[0111] In any of the foregoing embodiments, the GFF and / or the VOA can be included, which are not limited in the present application. Figures 2 to 7 In the embodiments of the present application, the types of the gain media in the n-stage gain media 2000 arranged in sequence are not limited. The n-stage gain media 2000 can be different types of gain media, which are not limited in the present application.

[0112] In the embodiments of the present application, the types of the gain media in the n-stage gain media 2000 arranged in sequence are not limited. The n-stage gain media 2000 can be different types of gain media, which are not limited in the present application.​​​​​​

[0113] In the embodiments of the present application, the different kinds of gain media can include doped optical fibers with different doping elements, doped optical fibers with different doping concentrations, or gain media with different structures, which are not limited in the present application.

[0114] For example, if the first-stage gain medium is an erbium-doped optical fiber and the second-stage gain medium is a bismuth-doped optical fiber, the first-stage gain medium and the second-stage gain medium are doped optical fibers with different doping elements. If the first-stage gain medium is a semiconductor optical amplifier (SOA) and the n-stage gain medium is an erbium-doped optical fiber, the first-stage gain medium and the n-stage gain medium are gain media with different structures. Optionally, optical fibers with different core diameters or different refractive indexes are also gain media with different structures, which are not limited in the present application. Figure 2 In an optional implementation, the number of the second gain media 2200 is multiple, and the multiple second gain media 2200 can also include multiple gain media of different kinds.

[0115] For example

[0116] As shown in FIG. 5, n = 5, m = 2, and k = 3. In the five-stage gain medium 2000, the first-stage and the second-stage gain media are the first gain medium 2100, and the third-stage to the fifth-stage gain media are the second gain medium 2200. The third-stage gain medium is an SOA, and the fourth-stage and the fifth-stage gain media are doped optical fibers. Therefore, the second gain medium 2200 includes multiple gain media of different kinds. Figure 10 In the optical amplifier described in the embodiments shown in FIG. 5, the optical amplifier can also include a control circuit. The control circuit is configured to control the output optical signal of the optical amplifier. Specifically, the control circuit can control at least one of the following of the output optical signal: output optical power, gain, tilt, etc., which are not limited in the present application.

[0117] Figures 2 to 10 Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the system, the device, and the unit described above can refer to the corresponding processes in the foregoing method embodiments, which will not be described herein.

[0118] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the system, the device, and the unit described above can refer to the corresponding processes in the foregoing method embodiments, which will not be described herein.

[0119] ​In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the described device embodiments are merely schematic. The division of the units is merely a logical function division. There can be another division manner for the actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0120] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments.

[0121] In addition, each functional unit in the embodiments of the present application can be integrated in a processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware, or in the form of a software functional unit.

[0122] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on such an understanding, the technical solutions of the present application essentially, or the part that contributes to the prior art, or all or a part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of the present application. The foregoing storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, and various other media that can store program codes. The computer software product can be distributed to a computer device, a server or a network device, etc., through a suitable medium, so that the computer device, the server or the network device, etc. can execute the methods in the embodiments of the present application by using the computer software product stored in the medium.

Claims

1. An optical amplifier characterized by, The n-stage gain medium comprises n-stage gain media arranged in sequence, an optical signal is input from a first-stage gain medium in the n-stage gain medium and output from an n-stage gain medium in the n-stage gain medium, the n-stage gain medium is used to amplify the input optical signal of the optical amplifier in sequence, and n≥2; The n-stage gain medium comprises a first gain medium and a second gain medium, the first gain medium is an mth gain medium in the n-stage gain medium, the second gain medium is at least one gain medium behind the first gain medium, The first gain medium and the second gain medium are different kinds of gain medium. The output end of the first gain medium is connected with the input end of the second gain medium; The average gain corresponding to the gain medium category to which the first gain medium belongs is greater than the average gain corresponding to the gain medium category to which the second gain medium belongs, and the average gain is the average gain of the gain medium to the signal in the working waveband.

2. The optical amplifier of claim 1, wherein, The maximum average gain of the gain medium category to which the first gain medium belongs is greater than the maximum average gain of the gain medium category to which the second gain medium belongs. The maximum average gain is the average gain of the gain medium to the signal in the working waveband at the optimal medium length, and the optimal medium length is the medium length corresponding to the maximum gain at different medium lengths.

3. The optical amplifier according to claim 1 or 2, characterized in that, m≥2, the n-stage gain medium arranged in sequence comprises a first-stage gain medium to an m-stage gain medium connected in sequence. The average gain of the gain medium category to which each-stage gain medium belongs in the first-stage gain medium to the m-stage gain medium connected in sequence is greater than the average gain of the gain medium category to which the second gain medium belongs.

4. The optical amplifier of claim 3, wherein, The first-stage gain medium to the m-stage gain medium connected in sequence are gain media of the same category.

5. The optical amplifier of any of claims 1, 2, or 4, wherein, m≤n / 3.

6. The optical amplifier of claim 1 or 2, wherein, m=1； If the number of the second gain media is 1, the output end of the first gain medium is connected with the input end of the second gain medium. If the number of the second gain media is greater than 1, the output end of the first gain medium is connected with the input end of the first-stage gain medium in the plurality of second gain media.

7. The optical amplifier of claim 6, wherein, In the n-stage gain medium arranged in sequence, the average gain of the gain medium category to which any gain medium belongs is greater than the average gain of the gain medium category to which the next-stage gain medium belongs.

8. The optical amplifier of any of claims 1, 2, or 4, wherein, m≥2, the n-stage gain medium further comprises a third gain medium, the third gain medium is a k-stage gain medium in the n-stage gain medium, k The average gain of the gain medium category to which the third gain medium belongs is less than the average gain of the gain medium category to which the first gain medium belongs.

9. The optical amplifier of any one of claims 1, 2, 4, or 7, wherein, The n-stage gain medium further comprises a fourth gain medium, the input end of the fourth gain medium is connected with the output end of the second gain medium, and the fourth gain medium and the second gain medium are gain media of different categories. The average gain of the gain medium category to which the fourth gain medium belongs is greater than the average gain of the gain medium category to which the second gain medium belongs.

10. The optical amplifier of any one of claims 1, 2, 4, or 7, wherein, There is a target gain medium in the at least one second gain medium, and the gain flatness of the target gain medium is better than the gain flatness of the first gain medium.

11. The optical amplifier of claim 10, wherein, The gain flatness of the gain medium in the at least one second gain medium is better than the gain flatness of the first gain medium.

12. The optical amplifier of claim 11, wherein, In the n-stage gain medium arranged in sequence, the gain flatness of any gain medium is better than the gain flatness of the previous-stage gain medium.

13. The optical amplifier of any one of claims 1, 2, 4, 7, 11, or 12, wherein, The second gain medium is multiple, and the multiple second gain mediums include multiple gain mediums of different types.

14. The optical amplifier of claim 13, wherein, The multiple gain mediums of different types include at least one of the following: Doped optical fibers with different doping elements, doped optical fibers with different doping concentrations, and gain mediums with different structures.

15. The optical amplifier of any one of claims 1, 2, 4, 7, 11, 12, or 13, wherein, Between the output end of the first gain medium and the input end of the second gain medium, a variable optical attenuator (VOA) and / or a gain-flattened filter (GFF) are further included. The GFF is used to balance the gain of the optical signal at each wavelength, and the VOA is used to adjust the gain point and the slope of the optical amplifier.

16. An optical communication device, comprising: The optical amplifier of any one of claims 1-15 is included.

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