Dynamic filtering device, optical amplification system, and dynamic filtering method

Abstract

A dynamic filtering device (1), an optical amplification system, and a dynamic filtering method. The dynamic filtering device (1) can be applied to an optical amplification system. Specifically, in the dynamic filtering device (1), a first light filtering element (20) is used for attenuating incoming target light, and a first control unit (10) controls the first light filtering element (20) to move to adjust the proportion of the target light passing through the first light filtering element (20), so as to flexibly adjust the amount of attenuation of the target light according to actual requirements. It should be understood that the amplitude of attenuation of the target light by the first light filtering element (20) is related to the wavelength of the target light, that is to say, for the target light having a certain wavelength range, the first light filtering element (20) can attenuate the target light at different wavelength positions to different extents in a targeted manner. The first light filtering element (20) is different from a VOA of which attenuation is unrelated to wavelength, the insertion loss introduced by the dynamic filtering device (1) using the first light filtering element (20) is low, and the noise figure is optimized.

Description

A dynamic filtering device, an optical amplification system and a dynamic filtering method

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on August 8, 2023, with application number 202310995550.0 and invention name “A dynamic filtering device, optical amplification system and dynamic filtering method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of optical transmission, and in particular to a dynamic filtering device, an optical amplification system, and a dynamic filtering method. Background Art

[0003] Optical amplifiers, particularly erbium-doped fiber amplifiers (EDFAs), have been widely used in the communications field, primarily to compensate for transmission fiber losses. EDFAs offer low noise and polarization-independence, enabling ultra-long-haul, repeater-free transmission. The intrinsic gain spectrum of the erbium-doped fiber in EDFAs typically fluctuates, with the difference between maximum and minimum gain reaching nearly 20dB.

[0004] Existing commercial gain-adjustable technology is achieved by adding variable optical attenuators (VOAs) between multiple optical amplifiers. Gain adjustment is achieved by adjusting the VOA's attenuation. However, VOAs introduce significant insertion loss and severely degrade the noise figure (NF).

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a dynamic filtering device, an optical amplification system, and a dynamic filtering method. The dynamic filtering device introduces low insertion loss and is conducive to optimizing the noise coefficient.

[0007] In a first aspect, embodiments of the present application provide a dynamic filtering device comprising an input port, an output port, a first control unit, and a first filter element. The first control unit is configured to control the movement of the first filter element to adjust the proportion of target light from the input port that passes through the first filter element. The first filter element is configured to attenuate the target light. The target light, after attenuation by the first filter element, is output from the output port. The target light is multi-wavelength light, i.e., it has a target wavelength range. As an example, in a scenario where the gain spectrum is flattened, the target wavelength range of the target light may be 1520nm-1580nm. As an example, in a scenario where bandpass filtering is implemented, the target light may cover light in the C-band, L-band, and S-band. It should be understood that the attenuation degree of the target light by the first filter element is related to the wavelength of the target light within the target wavelength range. In other words, the first filter element can specifically attenuate the target light to varying degrees at different wavelengths within the target wavelength range. It can be seen that the first filter element provided in the present application is different from the VOA whose attenuation is independent of wavelength. The dynamic filtering device using the first filter element introduces lower insertion loss and is conducive to optimizing the noise figure.

[0008] In some possible embodiments, for any two wavelengths within the target wavelength range, such as the first wavelength and the second wavelength. After the target light is amplified by the optical amplifier, the first gain of the target light of the first wavelength is greater than the second gain of the target light of the second wavelength. Accordingly, the first attenuation amplitude of the first filter element for the target light of the first wavelength is greater than the second attenuation amplitude of the first filter element for the target light of the second wavelength. That is to say, within the target wavelength range, the greater the gain corresponding to the wavelength, the greater the attenuation amplitude corresponding to the wavelength. Moreover, the gain change amplitude corresponding to the two wavelengths is the same or similar to the attenuation change amplitude corresponding to the two wavelengths. For example, the absolute value of the difference between the gain change amplitude between the first gain and the second gain and the attenuation change amplitude between the first attenuation amplitude and the second attenuation amplitude is less than a preset value, which can be 1dB or 2dB, etc., and is not specifically restricted here. In this way, the dynamic filtering device can flatten the originally fluctuating gain spectrum of the target light.

[0009] In some possible embodiments, the first control unit is specifically configured to obtain the average gain of the target light within a target wavelength range and control the displacement of the first filter element based on the average gain of the target light within the target wavelength range. It should be understood that the average gain of the input target light within the target wavelength range is not fixed, and the average gain is related to the amplitude of the gain variation of the target light within the target wavelength range. Therefore, the first control unit flexibly adjusts the proportion of the first filter element in the optical path based on the average gain, so as to flatten the gain spectrum of target light with different average gains, thereby adapting to a variety of different application scenarios.

[0010] In some possible embodiments, when the target light has a first average gain within the target wavelength range, the proportion of the target light passing through the first filter element is a first proportion. When the target light has a second average gain within the target wavelength range, the proportion of the target light passing through the first filter element is a second proportion. The first average gain is less than the second average gain, and the first proportion is greater than the second proportion. In other words, the smaller the average gain of the target light within the target wavelength range, the higher the proportion of the first filter element in the optical path should be, which helps to ensure a flat gain spectrum for the target light.

[0011] In some possible embodiments, the first control unit is specifically configured to obtain a gain variation amplitude of the target light within a target wavelength range, and control the displacement of the first filter element based on the gain variation amplitude of the target light within the target wavelength range. It should be understood that the first control unit can also flexibly adjust the proportion of the first filter element involved in the optical path by directly obtaining the gain variation amplitude of the target light, so as to flatten the gain spectrum of target light with different gain variation amplitudes, thereby improving the scalability of this solution.

[0012] In some possible embodiments, when the target light has a first gain variation within the target wavelength range, the proportion of the target light passing through the first filter element is a first proportion. When the target light has a second gain variation within the target wavelength range, the proportion of the target light passing through the first filter element is a second proportion. The first gain variation is greater than the second gain variation, and the first proportion is greater than the second proportion. In other words, the greater the gain variation of the target light, the greater the proportion of the first filter element involved in the optical path should be, which helps to ensure a flat gain spectrum for the target light.

[0013] In some possible embodiments, the target light includes light in a first wavelength band and light in a second wavelength band, and the dynamic filtering device further includes a second filter element and a second control unit. The first filter element is used to filter out the light in the first wavelength band, and the second filter element is used to filter out the light in the second wavelength band. The second control unit is used to control the movement of the second filter element to adjust the proportion of the target light passing through the second filter element. In other words, the dynamic filtering device can also use multiple filter elements to achieve a function similar to a bandpass filter. Furthermore, each control unit independently adjusts the displacement size of the corresponding filter element according to actual needs to adjust the proportion of the target light passing through the filter element, thereby flexibly adjusting the attenuation amplitude of the target light in this wavelength band.

[0014] In some possible embodiments, the dynamic filtering device further includes a light collimator. The light collimator is used to collimate the target light, and the first filter element is used to attenuate the collimated target light. It should be understood that the target light spot is larger after the light beam is collimated. This eliminates the need to place high demands on the control accuracy of the first control unit. Even a first control unit with poor control accuracy can flexibly adjust the proportion of target light passing through the first filter element by controlling the movement of the first filter element. Of course, for a first control unit with higher control accuracy, a light collimator may not be used.

[0015] In some possible implementations, the first control unit controls the movement of the first filter element using electrostatic, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor, or electrically controlled screw threading, thereby increasing the flexibility of this solution. For example, electrostatic, electrothermal, or piezoelectric microelectromechanical systems (MEMS) can be used to control the first filter element.

[0016] In some possible implementations, the input port is used to connect to an input optical fiber, and the output port is used to connect to an output optical fiber.

[0017] In a second aspect, embodiments of the present application provide an optical amplification system, comprising a first optical amplifier, a second optical amplifier, and a dynamic filtering device as described in any embodiment of the first aspect. The first optical amplifier is configured to amplify input light and transmit the amplified light to the dynamic filtering device. The second optical amplifier is configured to amplify light that has passed through the dynamic filtering device.

[0018] In some possible embodiments, the optical amplification system further includes a gain flattening filter (GFF). The GFF is used to filter light passing through the first optical amplifier. It should be understood that the GFF can also flatten the gain spectrum, but the GFF is primarily effective for light with a high average gain, while the dynamic filtering device provided herein is more effective for light with a low average gain. Therefore, the combination of the GFF and the dynamic filtering device can flatten gain spectra of varying specifications.

[0019] In a third aspect, embodiments of the present application provide a dynamic filtering method, which is applied to a dynamic filtering device. The dynamic filtering device includes an input port, an output port, a first control unit, and a first filter element. The dynamic filtering method includes the following steps: controlling the movement of the first filter element via the first control unit to adjust the proportion of target light from the input port that passes through the first filter element. The target light is attenuated by the first filter element. The target light, after attenuation by the first filter element, is output from the output port. The target light is multi-wavelength light, i.e., the target light has a target wavelength range. As an example, in a scenario where the gain spectrum is flattened, the target wavelength range of the target light may be 1520nm-1580nm. As an example, in a scenario where bandpass filtering is implemented, the target light may cover light in the C-band, L-band, and S-band. It should be understood that the attenuation degree of the target light by the first filter element is related to the wavelength of the target light within the target wavelength range. In other words, the first filter element can specifically attenuate the target light to varying degrees at different wavelengths within the target wavelength range. It can be seen that the first filter element provided in the present application is different from the VOA whose attenuation is independent of wavelength. The dynamic filtering device using the first filter element introduces lower insertion loss and is conducive to optimizing the noise figure.

[0020] In some possible embodiments, for any two wavelengths within the target wavelength range, such as the first wavelength and the second wavelength. After the target light is amplified by the optical amplifier, the first gain of the target light of the first wavelength is greater than the second gain of the target light of the second wavelength. Accordingly, the first attenuation amplitude of the first filter element for the target light of the first wavelength is greater than the second attenuation amplitude of the first filter element for the target light of the second wavelength. That is to say, within the target wavelength range, the greater the gain corresponding to the wavelength, the greater the attenuation amplitude corresponding to the wavelength. Moreover, the gain change amplitude corresponding to the two wavelengths is the same or similar to the attenuation change amplitude corresponding to the two wavelengths. For example, the difference between the gain change amplitude corresponding to the two wavelengths and the attenuation change amplitude corresponding to the two wavelengths is less than 2dB or 1dB, and the specific restrictions are not imposed here. In this way, the dynamic filtering device can flatten the originally fluctuating gain spectrum of the target light.

[0021] In some possible embodiments, controlling the movement of the first filter element by the first control unit includes: obtaining the average gain of the target light within the target wavelength range by the first control unit, and controlling the displacement of the first filter element according to the average gain of the target light within the target wavelength range.

[0022] In some possible implementations, the smaller the average gain of the target light within the target wavelength range, the higher the proportion of the first filter element inserted into the optical path should be, which is conducive to ensuring that the gain spectrum of the target light becomes flat.

[0023] In some possible embodiments, controlling the movement of the first filter element by the first control unit includes: obtaining the gain change amplitude of the target light within the target wavelength range by the first control unit, and controlling the displacement size of the first filter element according to the gain change amplitude of the target light within the target wavelength range.

[0024] In some possible implementations, the greater the gain variation of the target light, the higher the proportion of the first filter element inserted into the optical path should be, which is conducive to ensuring that the gain spectrum of the target light becomes flat.

[0025] In some possible embodiments, the target light includes light in a first wavelength band and light in a second wavelength band, and attenuating the target light through the first filter element includes: filtering out the light in the first wavelength band through the first filter element. The dynamic filtering device also includes a second filter element and a second control unit, and the method further includes: controlling the movement of the second filter element through the second control unit to adjust the proportion of the target light passing through the second filter element. Filtering out the light in the second wavelength band through the second filter element. Furthermore, each control unit independently adjusts the displacement size of the corresponding filter element according to actual needs to adjust the proportion of the target light passing through the filter element, thereby flexibly adjusting the attenuation amplitude of the target light in this wavelength band.

[0026] In some possible implementations, the dynamic filtering device further includes a light collimator. The method further includes: collimating the target light using the light collimator. Attenuating the target light using the first filter element includes: attenuating the collimated target light using the first filter element.

[0027] In some possible implementations, the first control unit controls the movement of the first filter element using electrostatic, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor, or electrically controlled screw threading. As an example, electrostatic, electrothermal, or piezoelectric MEMS can be used to control the first filter element.

[0028] In some possible implementations, the input port is used to connect to an input optical fiber, and the output port is used to connect to an output optical fiber.

[0029] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0030] The first filter element in the dynamic filtering device provided by the present application is used to attenuate the input target light. In addition, the first control unit adjusts the proportion of the target light passing through the first filter element by controlling the movement of the first filter element, so that the attenuation of the target light can be flexibly adjusted according to actual needs. It should be understood that the amplitude of the attenuation of the target light by the first filter element is related to the wavelength of the target light, that is, for target light with a certain wavelength range, the first filter element can be targeted to attenuate the target light at different wavelength positions to different degrees. It can be seen that the first filter element provided by the present application is different from the VOA whose attenuation is independent of the wavelength. The dynamic filtering device using the first filter element introduces a lower insertion loss and is conducive to optimizing the noise coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a schematic diagram of a first structure of a dynamic filtering device according to an embodiment of the present application;

[0032] FIG2 is a schematic diagram of several gain spectra before the target light is input into the dynamic filtering device;

[0033] FIG3 is a schematic diagram of several gain spectra of target light after it is output from the dynamic filtering device;

[0034] FIG4 is a schematic diagram of an attenuation spectrum of the first filter element;

[0035] FIG5 is a schematic diagram of a first embodiment of controlling the movement of the first filter element in the embodiment of the present application;

[0036] FIG6 is a schematic diagram of a second embodiment of controlling the movement of the first filter element in the embodiment of the present application;

[0037] FIG7 is a schematic diagram of a second structure of a dynamic filtering device according to an embodiment of the present application;

[0038] FIG8 is a schematic diagram of a first embodiment of controlling the movement of multiple filter elements in an embodiment of the present application;

[0039] FIG9 is a schematic diagram of a second embodiment of controlling the movement of multiple filter elements in an embodiment of the present application;

[0040] Figure 10 is a comparison of the noise figures of this solution and the traditional VOA solution;

[0041] FIG11 is a schematic structural diagram of an optical amplification system according to an embodiment of the present application;

[0042] FIG12 is a schematic diagram of an embodiment of a dynamic filtering method in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The embodiments of the present application provide a dynamic filtering device, an optical amplification system, and a dynamic filtering method. The dynamic filtering device introduces low insertion loss and is conducive to optimizing the noise figure. It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, rather than to limit a specific order or sequence. It should be understood that the above terms can be interchangeable where appropriate so that the embodiments described in this application can be implemented in an order other than that described in this application. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or devices.

[0044] Figure 1 is a schematic diagram of the first structural embodiment of a dynamic filtering device according to an embodiment of the present application. As shown in Figure 1 , the dynamic filtering device includes a first control unit 10, a first filter element 20, an input port 30, and an output port 40. Target light input from the input port 30 is transmitted to the output port 40 in the form of spatial light. This means that the input port 30 and the output port 40 do not need to be connected via a transmission medium such as an optical fiber or waveguide. Of course, in some possible scenarios, the dynamic filtering device can be connected to other devices via optical fibers connected to the input port 30 and the output port 40, respectively. Specifically, the first control unit 10 is used to control the movement of the first filter element 20 to adjust the proportion of target light from the input port that passes through the first filter element 20. In other words, the proportion of the first filter element 20 in the optical path of the target light can be flexibly adjusted according to actual needs. For example, the target light can all pass through the first filter element 20, or only a portion of the target light can pass through the first filter element 20, or none of the target light can pass through the first filter element 20.

[0045] The first optical filter element 20 is used to attenuate the target light from the input port 30. The target light, after being attenuated by the first optical filter element 20, is output from the output port 40. It should be understood that in some possible scenarios, the input port 30 is connected to a pre-amplifier and the output port 40 is connected to a post-amplifier. Assuming the target light does not pass through a dynamic filtering device, the gain of the target light within the target wavelength range may fluctuate. The dynamic filtering device designed in this application can flatten the gain of the target light within the target wavelength range. The attenuation degree of the target light by the first optical filter element 20 is related to the wavelength of the target light within the target wavelength range. It should be understood that the target light is amplified by an optical amplifier and has different gains at different wavelengths within the target wavelength range. Therefore, the first optical filter element 20 designed in this application can specifically attenuate the target light at different wavelengths within the target wavelength range to varying degrees, thereby flattening the gain spectrum of the target light after passing through the first optical filter element 20.

[0046] As an example, for any two wavelengths within the target wavelength range, such as a first wavelength and a second wavelength, the first gain of the target light of the first wavelength is greater than the second gain of the target light of the second wavelength. Accordingly, the first attenuation amplitude of the first filter element for the target light of the first wavelength is greater than the second attenuation amplitude of the first filter element for the target light of the second wavelength. That is, within the target wavelength range, the greater the gain corresponding to a wavelength, the greater the attenuation amplitude corresponding to that wavelength. Furthermore, the gain variation amplitude corresponding to the two wavelengths is the same as or similar to the attenuation variation amplitude corresponding to the two wavelengths. For example, the gain variation amplitude corresponding to the two wavelengths differs from the attenuation variation amplitude corresponding to the two wavelengths by less than 2dB or 1dB, although this is not a specific restriction. In this way, the dynamic filtering device can flatten the originally fluctuating gain spectrum of the target light. It should be understood that the flattening of the gain spectrum mentioned in this application does not necessarily mean that the gain spectrum has no fluctuations at all. For example, a gain spectrum with a gain fluctuation amplitude of less than 2dB can be considered a flat gain spectrum.

[0047] It should be noted that the original fluctuating gain spectrum of the target light can be detected in advance. Furthermore, combined with the desired flat gain spectrum after the target light passes through the dynamic filtering device, the attenuation spectrum of the first filter element 20 can be designed, that is, the attenuation amplitude of the first filter element 20 for the target light at each wavelength position within the target wavelength range can be determined.

[0048] It should be understood that the gain spectrum of the target light passing only through the optical amplifier without the dynamic filtering device is referred to as the original gain spectrum, while the gain spectrum of the target light passing through the optical amplifier and the dynamic filtering device is referred to as the target gain spectrum. In one possible scenario, the dynamic filtering device is provided with a pre-stage optical amplifier and a post-stage optical amplifier, respectively. Figure 2 below shows the original gain spectrum of the target light after passing through the post-stage optical amplifier, and Figure 3 below shows the target gain spectrum of the target light after passing through the post-stage optical amplifier.

[0049] Figure 2 is a schematic diagram of several original gain spectra of the target light. Figure 2 shows the original gain spectra of four target lights with different average gains within the target wavelength range. The horizontal axis in Figure 2 represents the wavelength (in nm) and the vertical axis represents the gain (in dB). As an example, as shown in Figure 2, the target wavelength range of the target light is 1520nm-1580nm. The four gain spectra shown in Figure 2 are a gain spectrum with an average gain of 23dB, a gain spectrum with an average gain of 26dB, a gain spectrum with an average gain of 29dB, and a gain spectrum with an average gain of 32dB. It can be seen from Figure 2 that the original gain spectrum of the target light fluctuates.

[0050] Figure 3 illustrates several target gain spectra for target light. The abscissa in Figure 3 represents wavelength (in nm), and the ordinate represents gain (in dB). Figure 3 illustrates the target gain spectra for four target lights with different average gains within the target wavelength range. Comparing Figure 3 with Figure 2 shows that the average gain of the target light remains stable, but the target gain spectrum becomes flatter relative to the original gain spectrum. For example, as shown in Figure 3, the gain difference between the maximum and minimum gain values ​​of the target light within the target wavelength range is less than or equal to 2 dB.

[0051] Figure 4 is a schematic diagram of an attenuation spectrum for a first optical filter element. The abscissa in Figure 4 represents wavelength (in nm), and the ordinate represents attenuation (in dB). It should be understood that in order to transform the fluctuating gain spectrum shown in Figure 2 into a flat gain spectrum as shown in Figure 3, the attenuation spectrum of the first optical filter element can be specifically designed as shown in Figure 4. It can be seen that the attenuation spectrum of the first optical filter element is wavelength-dependent, meaning that the attenuation amplitude of the first optical filter element may vary at different wavelengths. Taking the gain spectrum shown in Figure 2 as an example, the gain of target light near a wavelength of 1530 nm is lowest, while the gain of target light near a wavelength of 1570 nm is highest. Accordingly, as shown in Figure 4, the first optical filter element exhibits the lowest attenuation amplitude for target light near a wavelength of 1530 nm and the highest attenuation amplitude for target light near a wavelength of 1570 nm. In other words, the first optical filter element attenuates target light at wavelengths where the gain is typically higher, and attenuates target light at wavelengths where the gain is typically lower, thereby flattening the originally fluctuating gain spectrum. By comparing FIG. 4 with FIG. 2 , it can be seen that the change trend of the gain of the target light is the same as the change trend of the attenuation of the target light by the first filter element.

[0052] It should be noted that if the gain variation of the target light within the target wavelength range is greater, indicating greater fluctuations in the gain spectrum of the target light, the proportion of the first filter element 20 inserted into the target light's optical path should also be increased, so that the first filter element 20 can exert a greater attenuation effect on the target light, thereby ensuring that the gain spectrum with greater fluctuations is flattened. Conversely, if the gain variation of the target light within the target wavelength range is smaller, indicating less fluctuations in the gain spectrum of the target light, the proportion of the first filter element 20 inserted into the target light's optical path can be correspondingly reduced to weaken the attenuation effect of the first filter element 20 on the target light, thereby flattening the gain spectrum with less fluctuations. In other words, in one possible embodiment, the first control unit 10 adjusts the displacement of the first filter element 20 based on the gain variation of the target light within the target wavelength range.

[0053] It should be noted that the gain variation of the target light within the target wavelength range is related to the average gain of the target light within the target wavelength range. As shown in Figure 2, the gain variation of the target light is greatest when the average gain of the target light is 23 dB. As the average gain of the target light increases, the gain variation of the target light decreases. In another possible embodiment, the first control unit 10 controls the displacement of the first filter element 20 based on the average gain of the target light within the target wavelength range. It should be understood that the smaller the average gain of the target light within the target wavelength range, the greater the proportion of the first filter element 20 that intervenes in the optical path of the target light.

[0054] It should be understood that the average gain of the target light is not fixed, and this application does not limit its specific average gain range. For example, as shown in Figure 2, the average gain of the target light is between 23dB and 32dB. Given a defined average gain range for the target light, the first control unit 10 controls the displacement of the first filter element 20 for each average gain within this range to adjust the proportion of the first filter element 20 intervening in the target light's optical path. The specific relationship between the average gain of the target light and the proportion of the first filter element 20 intervening in the target light's optical path will depend on the actual application and is not limited here. As an example, if the average gain of the target light is 23dB, all the target light passes through the first filter element 20; if the average gain of the target light is 24dB, 90% of the target light passes through the first filter element 20; if the average gain of the target light is 25dB, 80% of the target light passes through the first filter element 20; and if the average gain of the target light is 32dB, none of the target light passes through the first filter element 20.

[0055] Optionally, as shown in FIG1 , the dynamic filtering device further includes a light collimator 50 . The target light input from the input port 30 is first collimated by the light collimator 50 . It should be understood that the target light spot is larger after beam collimation. This reduces the need for high control accuracy requirements for the first control unit 10 . Even a first control unit 10 with poor control accuracy can flexibly adjust the proportion of target light passing through the first filter element 20 by controlling the movement of the first filter element 20 . Of course, a first control unit 10 with higher control accuracy can also omit the light collimator 50 .

[0056] It should be noted that this application does not limit the direction in which the first control unit 10 controls the movement of the first filter element 20. Two possible implementations are provided below. Figure 5 is a schematic diagram of a first embodiment of controlling the movement of the first filter element in an embodiment of this application. Figure 6 is a schematic diagram of a second embodiment of controlling the movement of the first filter element in an embodiment of this application. As shown in Figure 5, the first control unit 10 controls the movement of the first filter element 20 in a first direction. As shown in Figure 6, the first control unit 10 controls the movement of the first filter element 20 in a second direction. As can be seen, the first direction is perpendicular to the second direction, expanding the application scenarios adapted by this solution.

[0057] It should be noted that the present application does not limit the specific type of the first control unit 10. For example, the first control unit 10 may control the movement of the first filter element 20 using electrostatic, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor, or electrically controlled screw threading. As an example, electrostatic, electrothermal, or piezoelectric microelectromechanical systems (MEMS) may be used to control the first filter element.

[0058] In some other possible scenarios, the dynamic filtering device may also use multiple filter elements to achieve a function similar to a bandpass filter. This implementation is introduced below.

[0059] FIG7 is a schematic diagram of a second structural embodiment of a dynamic filtering device in an embodiment of the present application. Unlike the structure shown in FIG1 , FIG7 shows a dynamic filtering device comprising multiple filter elements and multiple control units corresponding to the multiple filter elements. This application does not limit the specific number of filter elements and control units. For example, FIG7 includes: control unit 101, control unit 102, ..., control unit 10n, and filter elements 201, filter element 202, ..., filter element 20n. Each control unit is used to control the movement of a corresponding filter element to adjust the proportion of filtered target light passing through the filter element. In some possible embodiments, the control units may not correspond one-to-one with the filter elements, that is, the number of control units may be less than the number of filter elements. For example, a single control unit may control all filter elements. In another example, different control units may control some of the filter elements.

[0060] It should be understood that in this scenario, the attenuation amplitude of the target light by each filter element is also related to the wavelength of the target light within the target wavelength range. For example, filter element 201 is used to filter out target light in the first band within the target wavelength range and pass target light in other bands. In other words, filter element 201 has a larger attenuation amplitude for target light in the first band and a smaller attenuation amplitude for target light in other bands. For another example, filter element 202 is used to filter out target light in the second band within the target wavelength range and pass target light in other bands. In other words, filter element 202 has a larger attenuation amplitude for target light in the second band and a smaller attenuation amplitude for target light in other bands. Furthermore, each control unit independently adjusts the displacement of the corresponding filter element according to actual needs to adjust the proportion of target light passing through the filter element, thereby flexibly adjusting the attenuation amplitude of the target light in that band.

[0061] It should be noted that, for the embodiment shown in FIG7 , the present application also does not limit the direction in which each control unit controls the movement of the corresponding first filter element. Two possible implementations are provided below. FIG8 is a schematic diagram of a first implementation method for controlling the movement of multiple filter elements in an embodiment of the present application. FIG9 is a schematic diagram of a second implementation method for controlling the movement of multiple filter elements in an embodiment of the present application. As shown in FIG8 , each control unit controls the movement of the corresponding first filter element in a first direction. As shown in FIG9 , each control unit controls the movement of the corresponding filter element in a second direction. In other possible implementations, it is also possible that some control units control the movement of the corresponding filter elements in the first direction, while another control unit controls the movement of the corresponding filter elements in the second direction.

[0062] From the above introduction, it can be seen that the first filter element in the dynamic filtering device provided by the present application is used to attenuate the input target light. In addition, the first control unit adjusts the proportion of the target light passing through the first filter element by controlling the movement of the first filter element, so that the attenuation of the target light can be flexibly adjusted according to actual needs. It should be understood that the amplitude of the attenuation of the target light by the first filter element is related to the wavelength of the target light, that is, for target light with a certain wavelength range, the first filter element can be targeted to attenuate the target light at different wavelength positions to different degrees. It can be seen that the first filter element provided by the present application is different from the VOA whose attenuation is independent of the wavelength. The dynamic filtering device using the first filter element introduces a lower insertion loss and is conducive to optimizing the noise coefficient.

[0063] Figure 10 compares the noise figure of this solution with that of a traditional VOA solution. The abscissa in Figure 10 represents wavelength (in nm), and the ordinate represents the noise figure (in dB). As can be seen from Figure 10, this solution significantly improves the noise figure compared to the traditional VOA solution.

[0064] The following describes the application scenario of the dynamic filtering device in an optical amplification system.

[0065] FIG11 is a schematic diagram of the structure of an optical amplification system in an embodiment of the present application. As shown in FIG11 , the optical amplification system includes: a dynamic filtering device 1, a pre-stage optical amplifier 2, and a post-stage optical amplifier 3. The dynamic filtering device 1 can be any of the dynamic filtering devices described in the above embodiments and will not be described in detail here. The pre-stage optical amplifier 2 is used to amplify the input light and transmit the amplified light to the dynamic filtering device 1. The post-stage optical amplifier 3 is used to amplify the light that has passed through the dynamic filtering device 1. In some possible scenarios, the optical amplification system may retain only one of the pre-stage optical amplifier 2 and the post-stage optical amplifier 3.

[0066] Optionally, the optical amplification system further includes a gain flattening filter (GFF) 4. GFF 4 is used to filter light passing through the pre-stage optical amplifier 2. It should be understood that the GFF can also flatten the gain spectrum, but its effect is primarily significant for light with a higher average gain, while the dynamic filtering device provided herein is more effective for light with a lower average gain. Therefore, the combination of GFF 4 and dynamic filtering device 1 can flatten gain spectra of varying specifications.

[0067] In some possible scenarios, the GFF can also be integrated into a dynamic filtering device. For example, the position of the GFF is fixed, meaning that all light input to the dynamic filtering device passes through the GFF. If the input light has a high average gain, the GFF can flatten the gain spectrum of the light, and the first filter element does not need to be inserted into the optical path. In other words, the input light does not need to pass through the first filter element. If the input light has a low average gain, the GFF cannot flatten the gain spectrum of the light, and the first filter element needs to be inserted into the optical path to flatten the gain spectrum. In other words, the input light needs to pass through the first filter element, and the proportion of light passing through the first filter element is flexibly adjustable.

[0068] The following is an introduction to the dynamic filtering method provided in the embodiments of the present application.

[0069] FIG12 is a schematic diagram of an embodiment of a dynamic filtering method in an embodiment of the present application. It should be noted that the dynamic filtering method is implemented based on the dynamic filtering device described above. For an introduction to the dynamic filtering device, reference can be made to the relevant descriptions of the above embodiments, and no further details will be given here. In this example, the dynamic filtering method includes the following steps.

[0070] 1201. Control the movement of a first filter element through a first control unit.

[0071] In this embodiment, controlling the movement of the first filter element can adjust the proportion of the light path accessed by the first filter element, which is equivalent to adjusting the proportion of target light from the input port passing through the first filter element. It should be understood that the first control unit can drive the first filter element using, but is not limited to, MEMS, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor, or electrically controlled threaded advancement.

[0072] In one possible implementation, the first control unit adjusts the displacement of the first filter element based on a gain variation of the target light within the target wavelength range. In another possible implementation, the first control unit controls the displacement of the first filter element based on an average gain of the target light within the target wavelength range.

[0073] 1202. Attenuate the target light through a first filter element.

[0074] It should be understood that the target light has a target wavelength range, and the gain of the target light within the target wavelength range may fluctuate. The extent to which the first filter element attenuates the target light is related to the wavelength of the target light within the target wavelength range. In other words, the first filter element designed in this application can specifically attenuate the target light at different wavelengths within the target wavelength range to varying degrees, thereby flattening the gain spectrum of the target light after passing through the first filter element.

[0075] It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A dynamic filtering device, characterized in that: include: An input port, an output port, a first control unit and a first filter element; The first control unit is used to control the movement of the first filter element to adjust the proportion of the target light from the input port passing through the first filter element; The first filter element is used to attenuate the target light, wherein the target light attenuated by the first filter element is output from the output port, the target light has a target wavelength range, and the attenuation amplitude of the target light by the first filter element is related to the wavelength of the target light within the target wavelength range.

2. The dynamic filtering device according to claim 1, characterized in that: The target wavelength range includes a first wavelength and a second wavelength, the target light of the first wavelength has a first gain after amplification, the target light of the second wavelength has a second gain after amplification, the first gain is greater than the second gain, the first attenuation amplitude of the first filter element for the target light of the first wavelength is greater than the second attenuation amplitude of the first filter element for the target light of the second wavelength, and the absolute value of the difference between the gain change amplitude between the first gain and the second gain and the attenuation change amplitude between the first attenuation amplitude and the second attenuation amplitude is less than a preset value.

3. The dynamic filtering device according to claim 1 or 2, characterized in that: The target light is amplified by an optical amplifier, and the first control unit is specifically used for: Obtaining an average gain of the target light within the target wavelength range; The displacement size of the first filter element is controlled according to the average gain of the target light within the target wavelength range.

4. The dynamic filtering device according to claim 3, characterized in that: The average gain of the target light within the target wavelength range is inversely proportional to the ratio of the target light passing through the first filter element.

5. The dynamic filtering device according to claim 1 or 2, characterized in that: The target light is amplified by an optical amplifier, and the first control unit is specifically used for: Acquire a gain variation amplitude of the target light within the target wavelength range; The displacement of the first filter element is controlled according to the gain variation amplitude of the target light within the target wavelength range.

6. The dynamic filtering device according to claim 5, characterized in that: The gain variation amplitude of the target light within the target wavelength range is proportional to the ratio of the target light passing through the first filter element.

7. The dynamic filtering device according to claim 1, characterized in that: The target light includes light in a first wavelength band and light in a second wavelength band, and the first filter element is used to filter out the light in the first wavelength band; The dynamic filtering device further comprises a second filter element and a second control unit, wherein the second filter element is used to filter out light of a second wavelength band; The second control unit is used to control the movement of the second filter element to adjust the proportion of the target light passing through the second filter element.

8. The dynamic filtering device according to any one of claims 1 to 7, characterized in that: The dynamic filtering device also includes a light collimator; The light collimator is used to collimate the target light; The first filter element is used to attenuate the collimated target light.

9. The dynamic filtering device according to any one of claims 1 to 8, characterized in that: The first control unit controls the movement of the first filter element by electrostatic, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor or electrically controlled threaded advancement.

10. The dynamic filtering device according to any one of claims 1 to 9, characterized in that: The input port is used to connect to an input optical fiber, and the output port is used to connect to an output optical fiber.

11. An optical amplification system, characterized in that: include: A first optical amplifier, a second optical amplifier and a dynamic filtering device as claimed in any one of claims 1 to 10; The first optical amplifier is used to amplify the input light and transmit the amplified light to the dynamic filtering device; The second optical amplifier is used to amplify the light passing through the dynamic filtering device.

12. The optical amplification system according to claim 11, characterized in that: The optical amplification system also includes a gain flattening filter GFF; The GFF is used to filter the light passing through the first optical amplifier.

13. A dynamic filtering method, characterized in that: The method is applied to a dynamic filtering device, the dynamic filtering device comprising: an input port, an output port, a first control unit and a first filter element, and the method comprises: Controlling the movement of the first filter element by the first control unit to adjust the proportion of the target light from the input port passing through the first filter element; The target light is attenuated by the first filter element, wherein the target light attenuated by the first filter element is emitted from the The output port outputs that the attenuation amplitude of the target light by the first filter element is related to the wavelength of the target light.

14. The method according to claim 13, characterized in that The target wavelength range includes a first wavelength and a second wavelength, the target light of the first wavelength has a first gain after amplification, the target light of the second wavelength has a second gain after amplification, the first gain is greater than the second gain, the first attenuation amplitude of the first filter element for the target light of the first wavelength is greater than the second attenuation amplitude of the first filter element for the target light of the second wavelength, and the absolute value of the difference between the gain change amplitude between the first gain and the second gain and the attenuation change amplitude between the first attenuation amplitude and the second attenuation amplitude is less than a preset value.

15. The method according to claim 13 or 14, characterized in that The target light is amplified by the optical amplifier, and the first control unit controls the movement of the first filter element, which includes: The average gain of the target light within the target wavelength range is acquired by the first control unit, and the displacement of the first filter element is controlled according to the average gain of the target light within the target wavelength range.

16. The method according to claim 15, characterized in that The average gain of the target light within the target wavelength range is inversely proportional to the ratio of the target light passing through the first filter element.

17. The method according to claim 13 or 14, characterized in that The target light is amplified by the optical amplifier, and the first control unit controls the movement of the first filter element, which includes: The gain variation amplitude of the target light within the target wavelength range is acquired by the first control unit, and the displacement size of the first filter element is controlled according to the gain variation amplitude of the target light within the target wavelength range.

18. The method according to claim 17, characterized in that The gain variation amplitude of the target light within the target wavelength range is proportional to the ratio of the target light passing through the first filter element.

19. The method according to claim 13, characterized in that The target light includes light in a first wavelength band and light in a second wavelength band, and attenuating the target light by using the first filter element includes: Filter out light of a first wavelength band by using the first filter element; The dynamic filtering device further includes a second filter element and a second control unit, and the method further includes: Controlling the movement of the second filter element by the second control unit to adjust the proportion of the target light passing through the second filter element; The light of the second wavelength band is filtered out by the second filter element.

20. The method according to any one of claims 13 to 19, characterized in that The dynamic filtering device further includes a light collimator, and the method further includes: collimating the target light by the light collimator; Attenuating the target light by the first filter element includes: The collimated target light is attenuated by the first filter element.

21. The method according to any one of claims 13 to 20, characterized in that The first control unit controls the movement of the first filter element by electrostatic, electrothermal, piezoelectric, magnetostrictive, electrostrictive, linear motor or electrically controlled threaded advancement.

22. The method according to any one of claims 13 to 21, characterized in that The input port is used to connect to an input optical fiber, and the output port is used to connect to an output optical fiber.

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