ASE power spectrum control method and system for optical amplifier

Abstract

The present invention relates to an ASE power spectrum control method and system for an optical amplifier. Specifically, the ASE power spectrum control method includes: obtaining the gain control parameters of the multi-wavelength optical amplifier during normal gain control; based on the obtained gain control parameters, obtaining the typical noise index NF spectrum line and gain curve of the multi-wavelength optical amplifier under the gain control parameters; based on the obtained typical noise index NF spectrum line and gain curve, configuring the target power when the multi-wavelength optical amplifier is subjected to ASE power spectrum control; configuring the working state of the multi-wavelength optical amplifier based on the target power, and making the ASE power output by the multi-wavelength optical amplifier consistent with the target power. The present invention can quickly control the waveform of the ASE power spectrum to be close to the waveform of the gain spectrum, and can control the power slope of the ASE power spectrum.

Description

Technical Field

[0001] The present invention relates to a control method and system, in particular to an ASE power spectrum control method and system of an optical amplifier. Background Art

[0002] In optical communications, wavelength division multiplexing is a common means of increasing the capacity of optical transmission systems. On this basis, by further expanding the wavelength range, the capacity of optical transmission systems can be further effectively increased. With the increase of wavelength bandwidth, communication bandwidth and / or modulation rate, the total output power of each node in the optical transmission system is also increasing.

[0003] When light waves are transmitted in optical fibers, due to the stimulated Raman scattering (SRS) effect, energy is transferred from short-wavelength light waves to long-wavelength light waves, resulting in large differences in the power intensity of each channel during the transmission process, which has a significant impact on the stability of the system. In addition, when the wavelength division multiplexing optical transmission system is working, it is not necessarily in a state of full allocation of service channels, that is, there may be a situation where the wavelength increases or decreases. At this time, the impact of the SRS effect on the optical transmission system will become more serious.

[0004] During the test and debugging phase of the wavelength division multiplexing optical transmission system, it is generally necessary to simulate the scenario of full configuration of service channels. At this time, the amplifier power of each node can be adjusted to achieve the actual full configuration, which can reduce the system instability caused by the increase of services in the later stage. Due to the large number of service channels, if all service channels of all wavelength lists are configured, taking the full configuration of 40 channels in both directions as an example, the cost of light sources, electrical layer service boards, frames and other equipment can be as high as tens of millions of yuan, and the preparation cycle of these equipment is long; at the same time, during the test, the power consumption of the electrical layer service boards is large, the fan speed is high, and huge noise is generated.

[0005] In order to solve the problems existing in the test and debugging stage of the optical transmission system, a few real business wavelengths are generally selected according to the wavelength requirements, and the wavelengths of other services are filled by virtual light sources (or called "fake waves" or "filler waves", whose wavelength, power, wavelength bandwidth, etc. match the system requirements, but there is no business information. Therefore, real light sources and electrical layer business boards are not required) to simulate actual scenarios for system debugging and system testing. Among them, the electrical layer business boards are boards that support actual services, and the light sources are generally inserted into the electrical layer business boards.

[0006] At present, for virtual light sources, ASE light sources (such as ASE light sources based on EDFA principles, ASE light sources based on SOA, etc.) and wavelength selection devices (such as wavelength selection switches WSS, multi-channel wavelength combiner and demultiplexer devices) can generally be used to select appropriate wavelengths for use as filler waves.

[0007] From the above description, it can be seen that when the wavelength division multiplexing optical transmission system is opened, it will gradually expand the capacity according to demand, that is, by increasing the wavelength (channel) to expand the capacity. When there are fewer cascade spans and a smaller wavelength range, increasing or decreasing the wavelength will have less impact on the entire wavelength division multiplexing optical transmission system.

[0008] For ASE light sources, due to their high power, the output power is generally greater than 20dBm within the available wavelength range. If an ASE light source based on EDF amplification is used, its principle is the same as that of EDFA. In multi-span optical transmission systems, amplifiers are required for power amplification to compensate for the losses of passive components, optical fibers, etc. Furthermore, the wavelengths used in current multi-span transmission systems are mainly based on C-band and L-band, because the loss curves of EDFA (Erbium Doped Fiber Amplifier) ​​and transmission optical fibers are very well matched. It should be noted that in current multi-span transmission systems, the maximum wavelength range of C-band is 1524~1572nm, and the maximum wavelength range of L-band corresponds to 1575~1626nm.

[0009] For EDFA in multi-span multi-wavelength optical transmission systems, automatic gain control is generally used. Even if there is a drop or add wave, the power of each wavelength can be kept unchanged without considering the impact of transient effects. When the EDFA input is disconnected or there is no input power, the following two processing methods are generally used, in which the EDFA with a disconnected input or no input power is regarded as the current EDFA; specifically:

[0010] Method 1: Turn off the pump laser in the current EDFA. At this time, the current EDFA has no output power; that is, the current EDFA is turned off, and the EDFA after the current EDFA will also be turned off.

[0011] Once the line of the optical transmission system is restored (for example, the input end of the current EDFA has input power), all EDFAs will be gradually reopened and gradually controlled. At the same time, due to the opening of EDFA, the WSS in the optical transmission system will be gradually and slowly adjusted according to the signal wavelength and power, resulting in a long recovery time for the entire optical transmission system, and obvious transient effects after cascading, making it difficult to re-debug the optical transmission system.

[0012] Method 2: The current EDFA is not turned off. At this time, the current EDFA will output a relatively small power. Since there is no input signal, the power output by the current EDFA is the spontaneous emission power (ASE power). The EDFA after the current EDFA can work normally (the ASE power output by the current EDFA is regarded as the signal power of the subsequent EDFA).

[0013] When the line is restored, all EDFAs will be controlled according to the input power. At this time, compared with method 1, the control time is fast, and all EDFA control states will not change due to restarting. The difficulty of re-debugging the system is small, and the transient effect is not obvious. At the same time, other devices, such as WSS, do not need to re-debug and set parameters.

[0014] The shape of the ASE power spectrum of the ASE power, the ASE power and the parameters set when the EDFA is actually working (such as the gain setting value Gain (set), the noise figure NF, the attenuation of the internal VOA and other parameters) are closely related. If the ASE power spectrum of the EDFA (current EDFA) at the breakpoint is not controlled, the ASE power spectrum will not meet the use of the optical transmission system. After the subsequent EDFA cascade amplification, the unevenness (power slope) of the ASE power spectrum of each stage will increase sharply. Once the line is restored, it will produce a more serious transient effect and even damage the receiver. In addition, the WSS will also undergo a large adjustment due to the mismatch of the power spectrum, and the debugging time and difficulty of the optical transmission system will increase significantly. Summary of the invention

[0015] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide an ASE power spectrum control method suitable for an optical amplifier, which can quickly control the waveform of the ASE power spectrum to be close to the waveform of the gain spectrum and can control the power slope of the ASE power spectrum.

[0016] According to the technical solution provided by the present invention, a method for controlling the ASE power spectrum of an optical amplifier is used to control the ASE power spectrum output by a multi-wavelength optical amplifier with input light disconnected, and make the waveform of the ASE power spectrum close to the waveform of the gain curve of the multi-wavelength optical amplifier, wherein the ASE power spectrum control method includes:

[0017] Obtaining a gain control parameter of the multi-wavelength optical amplifier during normal gain control;

[0018] Based on the acquired gain control parameters, a typical noise figure NF spectrum line and a gain curve of the multi-wavelength optical amplifier under the gain control parameters are acquired;

[0019] Based on the typical noise figure NF spectrum and gain curve obtained, the target power for ASE power spectrum control of the multi-wavelength optical amplifier is configured;

[0020] The working state of the multi-wavelength optical amplifier is configured based on the target power, and the ASE power output by the multi-wavelength optical amplifier is made consistent with the target power.

[0021] The target power when performing ASE power spectrum control on the multi-wavelength optical amplifier is generated based on the target reference power, where:

[0022] The target reference power is calculated based on a typical noise figure NF spectrum line and a gain curve.

[0023] For the target reference power, we have:

[0024]

[0025] Wherein, Pase(Total) is the target reference power, ν is the frequency of the input light when the multi-wavelength optical amplifier is working, and the unit is Hz, h is the Planck constant, v1 is the starting frequency at which the multi-wavelength optical amplifier can amplify the optical signal, v2 is the ending frequency at which the multi-wavelength optical amplifier can amplify the optical signal, and the ending frequency v2 is greater than the starting frequency v1, NF(ν) is the typical noise index value determined based on the typical noise index NF spectrum line at the frequency ν, and G(ν) is the gain value determined based on the gain curve at the frequency ν.

[0026] For the target reference power, we have:

[0027] Pase(Total)=NF ave *G ave *hv ave (ν2-ν1)

[0028] Among them, Pase(Total) is the target reference power, NF ave is the average value of the typical noise index NF spectrum, G ave is the average gain of the gain curve, v1 is the starting frequency of the optical signal that the multi-wavelength optical amplifier can amplify, v2 is the ending frequency of the optical signal that the multi-wavelength optical amplifier can amplify, ν ave is the center frequency, center frequency ν ave It is the average value of the starting frequency ν1 and the ending frequency ν2. The ending frequency v2 is greater than the starting frequency v1. h is Planck's constant.

[0029] When the multi-wavelength optical amplifier has a GFF, the target power of the multi-wavelength optical amplifier is the sum of the target reference power and the control compensation value, wherein:

[0030] The control compensation value is 10*log (GFF bandwidth / amplifier bandwidth), wherein the GFF bandwidth is the working bandwidth of the GFF, and the amplifier bandwidth is the effective bandwidth of the multi-wavelength optical amplifier.

[0031] Obtaining gain control parameters of the multi-wavelength optical amplifier, including at least a gain setting value Gain(set);

[0032] Configuring the working state of the multi-wavelength optical amplifier and making the ASE power of the multi-wavelength optical amplifier consistent with the target power includes:

[0033] For multiple pump sources in the multi-wavelength optical amplifier, the pump powers of the pump sources are adjusted, and the ratio of the pump powers of the multiple pump sources after adjustment is adjusted so that the pump power ratio of the multiple pump sources remains consistent with the pump power ratio of the pump sources during normal gain control under typical minimum input conditions.

[0034] When the multi-wavelength optical amplifier includes a VOA, the acquired gain control parameter of the multi-wavelength optical amplifier also includes an attenuation value ATT(set) of the VOA, where:

[0035] When configuring the working state of the multi-wavelength optical amplifier, keep the attenuation value ATT(set) of the VOA unchanged.

[0036] When obtaining a typical noise index NF spectrum line under the gain control parameter, the noise index NF spectrum line of the multi-wavelength optical amplifier under typical input light and typical output light power is configured as the typical noise index NF spectrum line.

[0037] When configuring the power slope of the multi-wavelength optical amplifier, there are:

[0038] PowerTilt=PowerTiltc+k1*[Pase(total)2-Pase(total)c]+k2*[ATT(set)-ATT(set)c]

[0039] Wherein, PowerTilt is the target power slope of the multi-wavelength optical amplifier, PowerTiltc is the initial value of the power slope of the multi-wavelength optical amplifier, Pase(Total)c is the initial value of the control power when the power slope of the multi-wavelength optical amplifier is controlled, ATT(set)c is the initial value of the attenuation setting of the multi-wavelength optical amplifier with VOA, Pase(total)2 is the target slope control power after the power slope of the multi-wavelength optical amplifier is controlled, the unit of the slope control power Pase(total)2 is dBm, ATT(set) is the attenuation setting value of the multi-wavelength optical amplifier with VOA,

[0040] k1 and k2 are both calibration coefficients. For FGA type multi-wavelength optical amplifiers, ATT(set)-ATT(set)c is 0.

[0041] An ASE power spectrum control system for an optical amplifier includes a power spectrum control device, wherein, for any multi-wavelength optical amplifier, when the multi-wavelength optical amplifier is in an input light disconnected state, the power spectrum control device uses the ASE power spectrum control method described above to perform ASE power spectrum control on the multi-wavelength optical amplifier so that the shape of the ASE power spectrum is close to the shape of the gain curve of the multi-wavelength optical amplifier.

[0042] The advantages of the present invention are as follows: for any multi-wavelength optical amplifier, the ASE power spectrum of the multi-wavelength optical amplifier can be quickly controlled, and the shape of the ASE power spectrum can be made close to the shape of the gain curve under normal gain control. The multi-wavelength optical amplifier can also be quickly configured to perform power slope control, so that the ASE power output by the multi-wavelength optical amplifier is the target slope control power Pase (total) 2, and no additional ASE light source is required. Based on the control of the multi-wavelength optical amplifier, the ASE output and fill wave of the target slope control power Pase (total) 2 can also be quickly achieved, without the need for special board preparation, which greatly saves preparation time and preparation cost.

[0043] For multi-stage transmission systems with multi-wavelength optical amplifier equipment, when there is no input at a certain site, an ASE output spectrum with a specific power slope can be quickly realized to ensure the stability of the system when there is no signal light input. When the system recovers, it can quickly achieve normal working status and reduce transient and unstable effects caused by mode switching, system parameter readjustment, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention is a flow chart of an embodiment of the method for controlling the ASE power spectrum of a multi-wavelength optical amplifier.

[0045] Figure 2 The figure is a schematic diagram of an embodiment of a typical noise figure NF spectrum and a gain curve under a typical maximum output.

[0046] Figure 3 The figure is a schematic diagram of an embodiment of a typical noise figure NF spectrum and a gain curve under a typical minimum output.

[0047] Figure 4 A schematic diagram of an embodiment of the comparison between the ASE power spectrum and the multi-wavelength optical amplifier gain curve of the present invention.

[0048] Figure 5 The figure is a schematic diagram of an embodiment of the present invention for obtaining a power slope fitting function by fitting.

[0049] Figure 6 It is a schematic diagram of an embodiment of the multi-wavelength and multi-span optical transmission system of the present invention.

[0050] Figure 7 It is a schematic diagram of an embodiment of the present invention using an ASE light source to generate a fill wave.

[0051] Figure 8 It is a schematic diagram of another embodiment of the present invention for generating fill waves using an ASE light source. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with specific drawings and embodiments.

[0053] In order to quickly adjust the waveform of the ASE power spectrum to be close to the waveform of the gain spectrum, an ASE power spectrum adjustment method suitable for an optical amplifier is provided in one embodiment of the present invention, which is used to adjust the ASE power spectrum output by a multi-wavelength optical amplifier with input light disconnected, and make the waveform of the ASE power spectrum close to the waveform of the gain curve of the multi-wavelength optical amplifier, so as to obtain a flatter ASE power spectrum or an ASE power spectrum with a specific power slope, wherein the ASE power spectrum adjustment method comprises:

[0054] Obtaining a gain control parameter of the multi-wavelength optical amplifier during normal gain control;

[0055] Based on the acquired gain control parameters, a typical noise figure NF spectrum line and a gain curve of the multi-wavelength optical amplifier under the gain control parameters are acquired;

[0056] Based on the typical noise figure NF spectrum and gain curve obtained, the target power for ASE power spectrum control of the multi-wavelength optical amplifier is configured;

[0057] The working state of the multi-wavelength optical amplifier is configured based on the target power, and the ASE power output by the multi-wavelength optical amplifier is made consistent with the target power.

[0058] Personnel in the art know that narrowband filters are generally used in single-wavelength optical amplifiers, and wide-spectrum ASE power spectrum cannot be obtained; and for single-wavelength optical amplifiers that do not use narrowband filters, GFF (gain flattening filter) is generally not used in the single-wavelength optical amplifier, that is, the single-wavelength optical amplifier is generally only used for a single-wavelength environment, and the gain of a single wave itself is not flat. The non-flatness of the single-wavelength gain specifically means that the single-wavelength gain generally has no flatness index. In addition, when the single-wavelength amplifier is used for multi-wavelength amplification, the gain spectrum line is not flat or is not controlled itself. Therefore, for the single-wavelength optical amplifier, as mentioned above, a flat and better wide-spectrum ASE cannot be obtained. Therefore, in one embodiment of the present invention, the optical amplifier for ASE power spectrum regulation is a multi-wavelength optical amplifier, and the multi-wavelength optical amplifier is in an input light disconnection state, wherein the input light disconnection state means that the current multi-wavelength optical amplifier has no input light, such as due to factors such as splicing, fiber breaking, and human non-access to the input light, the current multi-wavelength optical amplifier has no input light signal, and the specific way of causing the input light disconnection is not limited.

[0059] In the case where the input light is disconnected, the ASE power spectrum output by the multi-wavelength optical amplifier is related to the gain curve and the typical noise figure NF (noise figure) spectrum of the multi-wavelength optical amplifier. Generally, for input light of the same frequency, the typical noise figure NF value of the multi-wavelength optical amplifier is less than the gain value of the multi-wavelength optical amplifier. Therefore, when adjusting the ASE power spectrum output by the multi-wavelength optical amplifier, the waveform of the ASE power spectrum output by the multi-wavelength optical amplifier is generally adjusted to be close to the waveform of the gain curve of the multi-wavelength optical amplifier. It can be seen from the above description that in the case where the input light is disconnected, when the waveform of the ASE power spectrum output by the multi-wavelength optical amplifier is close to the waveform of the gain curve of the multi-wavelength optical amplifier, the ASE power spectrum at this time is relatively flat, which can meet the needs of scenarios such as cascade debugging of multi-span multi-wavelength optical transmission systems.

[0060] Specifically, the typical noise index NF value refers to the noise index value corresponding to an input optical frequency selected on the typical noise index NF curve; similarly, the gain value of the multi-wavelength optical amplifier refers to the gain value corresponding to an input optical frequency selected on the gain curve.

[0061] In addition, for an optical transmission system in which multi-wavelength optical amplifiers are cascaded, for a multi-wavelength optical amplifier with input light disconnected, the waveform of the ASE power spectrum output by the multi-wavelength optical amplifier at the current node position should be close to the waveform of the corresponding gain curve of the multi-wavelength optical amplifier; at this time, it can be basically ensured that the ASE power spectrum and gain spectrum of the multi-wavelength optical amplifier without input light nodes in the multi-wavelength optical transmission system are close (relatively flat, or with a specific slope), where the gain spectrum is the gain curve of the multi-wavelength optical amplifier.

[0062] In an optical transmission system, a multi-wavelength optical amplifier is generally in a normal working state before the input light is disconnected. Therefore, after determining that the multi-wavelength optical amplifier is in the input light disconnected state, the gain control parameters of the multi-wavelength optical amplifier during normal gain control before the input light is disconnected can be obtained, wherein the gain control parameters can be obtained by existing commonly used technical means, and whether the multi-wavelength optical amplifier is in the input light disconnected state can be determined by monitoring the input light power of the multi-wavelength optical amplifier. The specific method and process for determining whether the multi-wavelength optical amplifier is in the input light disconnected state can be selected according to actual needs, and no examples are given here. The obtained gain control parameters are generally related to the type of the multi-wavelength optical amplifier, and are specifically explained below in combination with the type of the multi-wavelength optical amplifier.

[0063] After obtaining the gain control parameters, it is also necessary to obtain the typical noise index NF spectrum line and gain curve of the multi-wavelength optical amplifier under the gain control parameters, wherein the typical noise index NF spectrum line specifically refers to the curve of the corresponding noise index under the obtained gain control parameters and at different input light frequencies / wavelengths; the gain curve specifically refers to the curve of the corresponding gain value under the obtained gain control parameters and at different input light frequencies / wavelengths; the meanings of the typical noise index NF spectrum line and the gain curve are consistent with the existing ones. After obtaining the gain control parameters, the commonly used technical means in the technical field can be used to obtain the corresponding typical noise index NF spectrum line and gain curve of the multi-wavelength optical amplifier. The specific method and process of obtaining the typical noise index NF spectrum line and the gain curve can be consistent with the existing ones, and will not be repeated here.

[0064] After obtaining the gain control parameters, the typical noise figure NF spectrum under the gain control parameters, and the gain curve, the target power of the multi-wavelength optical amplifier for ASE power spectrum control can be configured. Thereafter, the ASE power output by the multi-wavelength optical amplifier is regulated with the target power as the target until the ASE power output by the multi-wavelength optical amplifier is consistent with the configured target power. At this point, it can be considered that the multi-wavelength optical amplifier is regulated. The specific regulation method is as follows: Figure 1 shown.

[0065] In specific implementation, the ASE power output by the multi-wavelength optical amplifier can be detected by a PD detector. When the output ASE power is detected to be consistent with the target power, it can be considered that the ASE power spectrum regulation of the multi-wavelength optical amplifier is completed. The method of using the PD detector to detect the ASE power output by the multi-wavelength optical amplifier is consistent with the existing method. The ASE power is consistent with the target power, which specifically means that the values ​​of the two are the same, or the difference between the values ​​of the two is within an allowable range. The allowable range is related to the working scenario of the multi-wavelength optical amplifier, etc., and can meet the actual application needs.

[0066] It should be noted that for a multi-wavelength optical amplifier, under the gain control parameter, there is a corresponding relationship between the power spectrum and the power, from which it can be known that there is also a corresponding relationship between the ASE power spectrum and the ASE power and the target power. The ASE power output by the multi-wavelength optical amplifier can be detected by a PD detector. At this time, the ASE power obtained by the detection can be regarded as the sum of the powers at different wavelengths, that is, by monitoring the power under the gain control parameter through the PD detector, the required ASE power spectrum can be obtained.

[0067] The target power when performing ASE power spectrum control on the multi-wavelength optical amplifier, the specific control method and process are explained in detail below.

[0068] In one embodiment of the present invention, when performing ASE power spectrum control on a multi-wavelength optical amplifier, at least a target reference power is obtained, wherein for the target reference power, there is:

[0069]

[0070] Wherein, Pase(Total) is the target reference power, ν is the frequency of the input light when the multi-wavelength optical amplifier is working, and the unit is Hz, h is the Planck constant, v1 is the starting frequency at which the multi-wavelength optical amplifier can amplify the optical signal, v2 is the ending frequency at which the multi-wavelength optical amplifier can amplify the optical signal, and the ending frequency v2 is greater than the starting frequency v1, NF(ν) is the typical noise index value determined based on the typical noise index NF spectrum line at the frequency ν, and G(ν) is the gain value determined based on the gain curve at the frequency ν.

[0071] In specific implementation, according to the working principle of the optical amplifier, the multi-wavelength optical amplifier can be divided into a doped optical amplifier DFA, a semiconductor optical amplifier SOA or a Raman optical amplifier ROA. Among them, the doped optical amplifier DFA can be an EDFA optical amplifier or an optical amplifier with other doped elements. The type of the doped optical amplifier DFA can be selected according to needs.

[0072] It can be seen from the above description that when the multi-wavelength optical amplifier is in the input light disconnected state, ASE power can also be output through the multi-wavelength optical amplifier. In one embodiment of the present invention, the ASE power output by the multi-wavelength optical amplifier is power spectrum controlled. It can be seen from the above description that the purpose of performing ASE power spectrum control at least includes controlling the waveform of the ASE power spectrum to be close to the waveform of the gain curve of the multi-wavelength optical amplifier, wherein the waveforms of the two are close, specifically referring to that the shapes of the two waveforms are consistent / similar, or the difference between the corresponding positions of the shapes of the two waveforms is within an allowable range.

[0073] The following takes an EDFA multi-wavelength optical amplifier as an example to specifically describe the method and process of calculating the target reference power Pase (Total).

[0074] When the multi-wavelength optical amplifier is an EDFA multi-wavelength optical amplifier, the gain control parameter of the multi-wavelength optical amplifier is obtained, wherein the gain control parameter at least includes a gain setting value Gain(set); the method of obtaining the gain setting value Gain(set) of the multi-wavelength optical amplifier can be consistent with the existing method. When the EDFA multi-wavelength optical amplifier has a VOA, the obtained gain control parameter should also include an attenuation setting value ATT(set) of the VOA, and the method of obtaining the attenuation setting value ATT(set) of the VOA can be consistent with the existing method, which will not be repeated here.

[0075] For EDFA multi-wavelength optical amplifiers, including erbium-doped optical fibers, after any EDFA multi-wavelength optical amplifier is manufactured, the length of the internal erbium-doped optical fiber (EDF) will be fixed, and the optimal flat gain of the EDFA multi-wavelength optical amplifier will also be fixed. When the EDFA multi-wavelength optical amplifier has a VOA, the current EDFA multi-wavelength optical amplifier can form an EDFA multi-wavelength optical amplifier with variable gain. Specifically, for the EDFA multi-wavelength optical amplifier with variable gain, the internal loss is generally adjusted through an internal variable attenuator (VOA), which is reflected in the external gain, that is, the external gain changes within a certain range. However, since the actual internal gain of the EDFA multi-wavelength optical amplifier does not change, the gain flatness of the EDFA multi-wavelength optical amplifier with variable gain remains unchanged.

[0076] For EDFA multi-wavelength optical amplifiers, gain flattening filters are generally used for gain flattening control. Otherwise, the EDFA multi-wavelength optical amplifier cannot meet the use requirements of the multi-wavelength system. Therefore, the gain spectrum of the EDFA multi-wavelength optical amplifier is generally flat, or maintains a certain gain tilt. The maintained gain tilt can compensate for the SRS effect. The gain tilt will not be very large, generally around 0 to -3dB. Otherwise, the signal power flatness of the optical transmission system cannot be guaranteed.

[0077] In the process of optical signal amplification, the output power corresponding to the optical signal of any frequency (or wavelength) within the unit frequency of the EDFA multi-wavelength optical amplifier can be expressed as:

[0078]

[0079] Among them, the typical noise index value NF(ν) changes relatively little, the gain value G(ν) is generally large, much greater than 1, and the typical noise index value NF(ν) is much smaller than the gain value G(ν), so 1 / G(ν) can be ignored in the calculation process. It can be seen that the overall contour shape of the output power Pase(ν) within the unit frequency range is generally closer to the overall contour shape of the gain curve.

[0080] Therefore, based on formula (2), the calculation expression of the target reference power when the EDFA multi-wavelength optical amplifier is subjected to ASE power spectrum control can be obtained, and the above formula (1) can be obtained. Since the product of frequency and wavelength is the speed of light, in the above formula, the frequency can be equivalently expressed by wavelength, where the wavelength is λ, and the unit is m (meter).

[0081] From the above description, it can be seen that for any EDFA multi-wavelength optical amplifier, when the output ASE power is consistent with the target power, the shape of the ASE power spectrum is relatively close to (or consistent with) the shape of the gain curve of the EDFA multi-wavelength optical amplifier, that is, when the input light is disconnected, the shape of the ASE power spectrum output by the EDFA multi-wavelength optical amplifier can be adjusted to be close to the gain curve of the EDFA multi-wavelength optical amplifier.

[0082] For EDFA multi-wavelength optical amplifiers, when the gain tilt is 0, there are certain requirements for the flatness of the gain curve. When expressed by Gain flatness, the gain flatness is generally less than 1.5dB. Furthermore, when the power of the input light of the EDFA multi-wavelength optical amplifier is small enough, it can be considered as no input power (theoretically, it is the power of a single photon at this time), but the above formula (1) still holds true, so based on formula (1), the target reference power Pase (Total) of the EDFA multi-wavelength optical amplifier when performing ASE power spectrum control is obtained; based on the target reference power Pase (Total), the target power can be obtained.

[0083] When the input light is disconnected, when the ASE power output by the EDFA multi-wavelength optical amplifier is regulated to be consistent with the target power, the waveform of the ASE power spectrum can be guaranteed to be close to the waveform of the gain curve of the multi-wavelength optical amplifier, and an ASE power spectrum with basically consistent power flatness and gain flatness can be obtained; of course, when the ASE power spectrum of the EDFA multi-wavelength optical amplifier is regulated, it is necessary to at least keep the pump ratio in the EDFA multi-wavelength optical amplifier unchanged; in addition, when the EDFA multi-wavelength optical amplifier has a VOA, it is also necessary to keep the attenuation setting value ATT(set) of the VOA in the EDFA multi-wavelength optical amplifier unchanged; it can be seen from the above description that regulating the ASE power spectrum of the EDFA multi-wavelength optical amplifier specifically refers to regulating the ASE power of the EDFA multi-wavelength optical amplifier to be consistent with the target power.

[0084] It can be seen from the above description that when regulating the EDFA multi-wavelength optical amplifier, it is necessary to make the ASE power output by the EDFA multi-wavelength optical amplifier consistent with the target power while keeping the pump ratio in the EDFA multi-wavelength optical amplifier unchanged. When the EDFA multi-wavelength optical amplifier has a VOA, it is necessary to keep the attenuation setting value ATT(set) of the VOA in the EDFA multi-wavelength optical amplifier unchanged, and then adjust the pump output in the EDFA multi-wavelength optical amplifier, and keep the pump ratio unchanged until the ASE power output by the EDFA multi-wavelength optical amplifier is consistent with the target power. Specifically, the pump ratio in the multi-wavelength optical amplifier specifically refers to the ratio of the pump powers output by multiple pump sources, and the pump power remains unchanged, specifically refers to the ratio of the pump powers output by multiple pump sources remains unchanged.

[0085] It should be noted that when the power of the input light is different, the gain of the EDFA multi-wavelength optical amplifier remains unchanged, but the typical noise index NF spectrum line of the EDFA multi-wavelength optical amplifier will change relatively greatly, especially when the power of the input light is small, due to more or insufficient pump excitation (related to the optical path design), the noise index NF spectrum line and the typical noise index NF spectrum line will change greatly.

[0086] In view of the above description, the change of the noise index NF spectrum under different input optical powers, in one embodiment of the present invention, when obtaining the typical noise index NF spectrum under the gain control parameter, the noise index spectrum under the typical input optical power and the typical output optical power is the typical noise index NF spectrum. Preferably, the typical output optical power can generally be selected as the maximum output optical power under normal gain conditions.

[0087] From the above description, it can be seen that the typical noise index NF spectrum line specifically refers to the NF spectrum line corresponding to the typical input optical power and the typical output optical power (here refers to the maximum output optical power) at different gains. For EDFA multi-wavelength optical amplifiers, the maximum output optical power is generally defined as the saturation power. For example, the gain of the EDFA multi-wavelength optical amplifier is 20dB, the input optical power is -20~0dBm, and the output optical power requirement is 0~20dBm. At this time, the typical input optical power is 0dBm, and the typical output optical power is 20dbm.

[0088] In addition, within the actual frequency (wavelength) range, the typical noise index NF spectrum and gain curve change relatively little. When the average value is taken for calculation, the above formula (1) can be further simplified, and another calculation method for the target reference power Pase (Total) can be obtained, which is as follows:

[0089]

[0090] Among them, NF ave is the average value of the typical noise index NF spectrum, G ave is the average gain of the gain curve, ν ave is the center frequency, center frequency ν ave That is the average value of the starting frequency ν1 and the ending frequency ν2.

[0091] When the gain control of EDFA multi-wavelength optical amplifier is performed, it is usually based on the average gain G ave At this time, the average gain G ave It can be regarded as equal to the gain setting value Gain(set), or within the control window required by the gain setting value Gain(set). That is, in the EDFA multi-wavelength optical amplifier, the average gain G is generally stored.ave , or the average gain G can be determined according to the gain setting value Gain(set) ave However, in EDFA multi-wavelength optical amplifiers, the typical noise index NF spectrum line or the average value NF of the typical noise index NF spectrum line is generally not saved. ave At this time, the average value of the typical noise index NF spectrum line is NF ave , you can use the following method to quickly obtain:

[0092] Find the average gain G in the EDFA multi-wavelength optical amplifier specification ave , and based on the average gain G ave The corresponding noise figure NF estimated value is estimated, and then the noise figure NF estimated value can be used as the average value NF of the typical noise figure NF spectrum line ave ; Among them, the average gain G ave The estimated value of the noise figure NF under the condition can be defined as the maximum value of the noise figure NF(ν) within the working wavelength range. At this time, if the estimated value of the noise figure NF is used to calculate the target reference power Pase(Total) of the EDFA multi-wavelength optical amplifier, the calculated target reference power Pase(Total) will generally be too large.

[0093] In order to reduce the deviation of the calculated target reference power Pase(Total), the estimated value of the noise index NF can be deducted by (0.5~1)dB according to experience, and used as the average value NF of the corresponding typical noise index NF spectrum line when calculating the target reference power Pase(Total). ave In specific implementation, find and obtain the average gain G ave Afterwards, the corresponding noise index NF estimated value may be estimated by using commonly used technical means in the technical field, and the specific method of estimating the noise index NF estimated value may be consistent with the existing estimation method.

[0094] In addition, if there is a device that can test OSNR, the test device can be used to test the EDFA multi-wavelength optical amplifier to obtain the actual noise index NF spectrum line or OSNR of the EDFA multi-wavelength optical amplifier. Specifically, the method of using the OSNR test device to test and obtain the noise index NF spectrum line is a commonly used test method in the technical field. The specific method of testing and obtaining the noise index NF spectrum line will not be repeated here. It can be understood that after the actual noise index NF spectrum line is measured, the average value NF of the typical noise index NF spectrum line can be calculated. ave .

[0095] In addition, the typical noise index NF spectrum line and / or the average value NF of the typical noise index NF spectrum line can be converted into aveStored in the EDFA multi-wavelength optical amplifier, when the typical noise index NF spectrum line and / or the average value NF of the typical noise index NF spectrum line is stored in the EDFA multi-wavelength optical amplifier ave When the typical noise index NF spectrum line and / or the average value NF of the typical noise index NF spectrum line can be directly extracted, ave , at this time, the above estimation process can be omitted.

[0096] The following is a specific example to illustrate the calculation process of the target reference power Pase (Total) of an EDFA multi-wavelength optical amplifier: For a certain EDFA multi-wavelength optical amplifier, the wavelength range is 1525-1572nm, the gain setting value Gain (set) is 32dB, the typical input optical power is -6dBm, the maximum output optical power is 26dBm, and the average gain G ave When the noise index is 32dB, the typical NF spectrum and gain curve are as follows: Figure 2 and Figure 3 As shown, Figure 2 FIG. 1 is a schematic diagram of an embodiment of a typical noise figure NF spectrum and a gain curve under typical minimum input conditions. Figure 3 The figure is a schematic diagram of an embodiment of a typical noise figure NF spectrum and a gain curve under typical maximum input conditions.

[0097] In specific implementation, for typical minimum input conditions, the input optical power is -29dBm, the output optical power is 3dBm, and the average gain G ave When it is 32dB, the typical noise index NF spectrum line is directly related to the pump power ratio. In order to ensure that the typical noise index NF spectrum line under the typical minimum input condition is basically consistent with the typical noise index NF spectrum line under the typical maximum input condition, the pump power in the EDFA multi-wavelength optical amplifier needs to be adjusted. For example, the ratio of the three pump powers in the EDFA multi-wavelength optical amplifier can be set to 2:2:1. At this time, the typical noise index NF spectrum line under the typical minimum input condition is basically consistent with the typical noise index NF spectrum line under the typical maximum output condition. Figure 3 It should be noted that the pump power is the output power of the pump source, and the pump power of the present invention has the same meaning, and the specific description can be referred to here.

[0098] For the above Figure 2 and Figure 3The typical noise index NF spectrum line shown in the figure is calculated by using formula (1) and integrating the calculation according to the wavelength interval of 1nm. The target reference power Pase (Total) of the EDFA multi-wavelength optical amplifier within the effective bandwidth is calculated to be 6.2dBm. When the target reference power Pase (Total) is calculated by using formula (3), the target reference power Pase (Total) within the effective bandwidth of the EDFA multi-wavelength optical amplifier is calculated to be 6.2dBm. Based on formula (3), the maximum typical noise index value of the typical noise index NF spectrum line is used as the average value NF of the typical noise index NF spectrum line. ave When the target reference power Pase(Total) of the EDFA multi-wavelength optical amplifier within the effective bandwidth is calculated, the result is: 6.4dBm.

[0099] From the above description, it can be seen that when the target reference power Pase(Total) is calculated using formula (1), when the number of sample points of the typical noise index NF spectrum line and the gain curve is sufficient, the calculation accuracy can be guaranteed; when the target reference power Pase(Total) is calculated using formula (3), even if the maximum typical noise index value of the typical noise index NF spectrum line is used as the average value NF of the typical noise index NF spectrum line, the calculation accuracy can be guaranteed. ave , the calculated value of the target reference power Pase(Total) of the EDFA multi-wavelength optical amplifier within the effective bandwidth can also be guaranteed to be within a reasonable accuracy.

[0100] From the above description, it can be seen that the relationship between the number of sample points and the accuracy of the typical noise index NF spectrum and gain curve is: for example, in the wavelength range of 1530-1560nm, if the wavelength is integrated at 1nm intervals, it is 31 points; if the wavelength is integrated at 0.1nm intervals, it is 301 points. The wavelength integration at 10nm intervals has only 4 points. At this time, when the target reference power Pase(Total) is calculated using formula (3), the corresponding calculation result has poor accuracy. It can be seen that when the target reference power Pase(Total) is calculated using formula (3), the fewer the points, the less accurate the average value, that is, the accuracy of the calculated target reference power Pase(Total) is poor.

[0101] When the EDFA multi-wavelength optical amplifier is in the input light disconnected state, the output power of the EDFA multi-wavelength optical amplifier only has ASE power. When the ASE power of the EDFA multi-wavelength optical amplifier within the effective bandwidth is controlled to be the target reference power Pase(Total) calculated above, the ASE power spectrum and gain curve of the EDFA multi-wavelength optical amplifier are as follows: Figure 4As shown in the figure, the flatness of the ASE power spectrum and the flatness of the gain curve are at the same order of magnitude (about 1 dB), and the shapes are relatively consistent. Specifically, the effective bandwidth range refers to the actual working wavelength range of the optical transmission system, such as the wavelength range between the wavelength corresponding to the starting frequency mentioned above and the wavelength corresponding to the end frequency.

[0102] It should be noted that EDFA multi-wavelength optical amplifiers generally have GFFs. Generally, the loss of GFFs outside the effective bandwidth is very large, and the ASE power spectrum will be suppressed outside the effective bandwidth. Therefore, for EDFA multi-wavelength optical amplifiers, when the output ASE power is equal to the target power, the accuracy requirements for ASE power spectrum control can be basically met. In addition, the effective bandwidth of GFF is wider than that of EDFA multi-wavelength optical amplifiers. If the accuracy of ASE power spectrum control is further pursued, the ASE power of EDFA multi-wavelength optical amplifiers can be controlled to the target reference power Pase (Total) + 10 * log (GFF bandwidth / amplifier bandwidth). For example, EDFA multi-wavelength optical amplifiers require a bandwidth of 1530 ~ 1560nm, and the bandwidth of GFF is assumed to be:

[0103] 1) When the bandwidth of GFF is 1529.5~1561nm, then:

[0104] 10*log((1561-1529.5) / (1560-1530))≈0.2dB;

[0105] 2) When the bandwidth of GFF is 1529-1568nm, then:

[0106] 10*log((1568-1529) / (1560-1530))≈1.1dB;

[0107] Therefore, when the ASE power is consistent with the target power, a feasible method is: the ASE power is equal to the target reference power Pase(Total), or the ASE power is 10*log(GFF bandwidth / amplifier bandwidth) greater than the target reference power Pase(Total), 10*log(GFF bandwidth / amplifier bandwidth) can be the control compensation value, wherein the control compensation value can be approximately calculated based on 10*log(GFF bandwidth / amplifier bandwidth), wherein the amplifier bandwidth is the effective bandwidth of the multi-wavelength optical amplifier.

[0108] In summary, it can be obtained that the target power may be the target reference power Pase(Total), or the sum of the target reference power Pase(Total) and the control compensation value, wherein the control compensation value may be 10*log(GFF bandwidth / amplifier bandwidth).

[0109] The above shows an embodiment of determining the target power of a multi-wavelength optical amplifier when the multi-wavelength optical amplifier is an EDFA multi-wavelength optical amplifier. When the multi-wavelength optical amplifier is a semiconductor optical amplifier SOA or a Raman optical amplifier ROA, the method and process description of the above EDFA multi-wavelength optical amplifier can be referred to and will not be repeated here.

[0110] It can be seen from the above description that for a multi-wavelength optical amplifier with a variable attenuator, when the multi-wavelength optical amplifier is configured to work as an ASE light source, the following states need to be maintained, including:

[0111] While maintaining the attenuation value ATT(set) of the VOA, for multiple pump sources in the multi-wavelength optical amplifier, a ratio of pump powers of the multiple pump sources is configured, wherein the ratio of pump powers of the multiple pump sources is configured so that the ratio of pump powers of the multiple pump sources remains consistent with the ratio of pump powers of the pump sources during normal gain control under typical minimum input conditions.

[0112] When the ASE power spectrum output by the multi-wavelength optical amplifier is required to have a power slope, it is also necessary to perform power slope control on the ASE power spectrum output by the multi-wavelength optical amplifier. When the power slope control is performed on the multi-wavelength optical amplifier, it specifically refers to controlling the ASE power output by the multi-wavelength optical amplifier to a target slope control power, wherein the target slope control power is related to the target power slope.

[0113] In specific implementation, after the ASE power of the multi-wavelength optical amplifier is adjusted to the target power, the initial value of the power output by the multi-wavelength optical amplifier can be obtained, and the ASE power is equal to the gain slope of the target gain. When the power slope of the multi-wavelength optical amplifier is further adjusted, the output power of the multi-wavelength optical amplifier is compared with the initial value of the power slope, that is, compared with the ASE power output by the multi-wavelength optical amplifier. At this time, the output power of the multi-wavelength optical amplifier does not need to be associated with the gain curve.

[0114] The following is a detailed description of the method for configuring the target slope of the multi-wavelength optical amplifier to control the power.

[0115] In one embodiment of the present invention, when configuring the power slope of the multi-wavelength optical amplifier, there is:

[0116] PowerTilt=PowerTiltc+k1*[Pase(total)2-Pase(total)c]+k2*[ATT(set)-ATT(set)c] (4)

[0117] Wherein, PowerTilt is the target power slope of the multi-wavelength optical amplifier, PowerTiltc is the initial value of the power slope of the multi-wavelength optical amplifier, Pase(Total)c is the initial value of the control power when the power slope of the multi-wavelength optical amplifier is controlled, ATT(set)c is the initial value of the attenuation setting of the multi-wavelength optical amplifier with VOA, Pase(total)2 is the target slope control power after the power slope of the multi-wavelength optical amplifier is controlled, the unit of the slope control power Pase(total)2 is dBm, ATT(set) is the attenuation setting value of the multi-wavelength optical amplifier with VOA, and k1 and k2 are both calibration coefficients;

[0118] For FGA type multi-wavelength optical amplifiers, ATT(set)-ATT(set)c is 0.

[0119] It should be noted that, according to whether the gain can be adjusted and the state of gain flatness at different gains, the multi-wavelength optical amplifier can be divided into: FGA type multi-wavelength optical amplifier or VGA type multi-wavelength optical amplifier, among which, the FGA type multi-wavelength optical amplifier cannot achieve constant gain flatness at different gains, while the VGA type multi-wavelength optical amplifier can achieve constant gain flatness at different gains; it can be seen that for the VGA type multi-wavelength optical amplifier, ATT(set)-ATT(set)c may not be 0; and the VGA type multi-wavelength optical amplifier generally has a VOA.

[0120] From the above description, it can be seen that when the multi-wavelength optical amplifier is an FGA type multi-wavelength optical amplifier, ATT-ATT(set)c is 0. Therefore, it can be seen that when the multi-wavelength optical amplifier is an FGA type multi-wavelength optical amplifier, when configuring the target slope control power of the multi-wavelength optical amplifier, there is:

[0121] PowerTilt_FGA= PowerTiltc_FGA+k1-1*[Pase_FGA(total)-Pase(total)c1_FGA] (5)

[0122] Among them, Pase_FGA(total) is the target slope control power of the FGA type multi-wavelength optical amplifier, the unit of the target slope control power is dBm, k1-1 is the calibration coefficient when the FGA type multi-wavelength optical amplifier performs power slope control, PowerTiltc_FGA is the initial value of the power slope of the FGA type multi-wavelength optical amplifier, Pase(total)c1_FGA is the initial value of the slope control power when the FGA type multi-wavelength optical amplifier performs ASE power spectrum control. PowerTilt_FGA is the target power slope of the multi-wavelength optical amplifier when the FGA type multi-wavelength optical amplifier performs power slope control.

[0123] Specifically, for the FGA type multi-wavelength optical amplifier, since there is no VOA inside the FGA type multi-wavelength optical amplifier to adjust the internal loss, at this time, the ASE power of the output FGA type multi-wavelength optical amplifier can be adjusted to control the shape of the ASE power spectrum of the FGA type multi-wavelength optical amplifier, specifically satisfying the above formula (5). At this time, the power slope of the FGA type multi-wavelength optical amplifier is at the target power slope PowerTilt_FGA; specifically, when the ASE power of the FGA type multi-wavelength optical amplifier is adjusted, the pump ratio in the multi-wavelength optical amplifier can be adjusted to achieve that the pump power ratio of multiple pump sources is kept consistent with the pump power ratio of the pump sources during normal gain control under typical minimum input conditions; when the ASE power of the FGA type multi-wavelength optical amplifier is the target slope control power Pase_FGA (total), the FGA type multi-wavelength optical amplifier is at the target power slope PowerTilt_FGA.

[0124] The calibration coefficient k1-1 can generally be a linear coefficient to meet the control progress requirements. Of course, multi-order fitting can also be used. The k1-1 value corresponds to different values ​​at different wavelengths. For the C-band wavelength range of 1525 to 1572nm, the typical value of the calibration coefficient k1-1 is about -1.1 to -1.2.

[0125] Furthermore, when the multi-wavelength optical amplifier is a VGA type multi-wavelength optical amplifier, when configuring the target power of the multi-wavelength optical amplifier, there are:

[0126] PowerTilt_VGA=PowerTiltc_VGA+k1-2*[Pase_VGA(total)-Pase(total)c2_VGA]

[0127] +k2*[ATT(set)-ATT(set)c](6) Wherein, Pase_VGA(total) is the target tilt control power of the VGA type multi-wavelength optical amplifier, Pase(total)c2_VGA is the initial value of the tilt control power when the VGA type multi-wavelength optical amplifier performs power tilt control. k1-2 is the calibration coefficient when the VGA type multi-wavelength optical amplifier performs power tilt control, PowerTiltc_VGA is the initial value of the power tilt of the VGA type multi-wavelength optical amplifier, and PowerTilt_VGA is the target power tilt of the multi-wavelength optical amplifier when the VGA type multi-wavelength optical amplifier performs power tilt control.

[0128] Specifically, for the VGA type multi-wavelength optical amplifier, since there is a VOA inside the VGA type multi-wavelength optical amplifier to adjust the internal loss, at this time, under the gain setting value Gain(set) (when the input light is disconnected, the gain setting value Gain(set) does not need to be adjusted at this time) and the attenuation setting value ATT(set), while keeping the output ASE power unchanged, the attenuation setting value ATT(set) can be changed, thereby obtaining the target power slope PowerTilt_VGA of the VGA type multi-wavelength amplifier of the above formula (6).

[0129] In addition, when the power slope of the VGA type multi-wavelength optical amplifier is controlled, the pump ratio of the VGA type multi-wavelength optical amplifier can also be adjusted so that the pump power ratio of multiple pump sources remains consistent with the pump power ratio of the pump sources during normal gain control under typical minimum input conditions; of course, the pump ratio and the attenuation setting value ATT(set) of the VOA can also be adjusted at the same time, and the specific adjustment method can be selected according to needs.

[0130] For the calibration coefficient k2, a linear fitting coefficient can generally be used to meet the control progress requirements. Of course, multi-order fitting can also be used. The calibration coefficient k2 value corresponds to different values ​​at different wavelengths. For the C-band wavelength range of 1525 to 1572nm, the typical value of the calibration coefficient k2 is about -1.0 to -1.1.

[0131] As can be seen from the above description, the above formula (4) can configure the corresponding target power for different types of multi-wavelength optical amplifiers. The specific method of configuring the target power can refer to the above formula and the corresponding description. For the calibration coefficient k1-2, the description of the calibration coefficient k1-1 can be referred to, and the two can have the same value range.

[0132] It can be seen from the above description that for a multi-wavelength optical amplifier, when performing power slope control, it is necessary to at least configure the target power slope PowerTilt of the multi-wavelength optical amplifier, the initial value of the power slope PowerTiltc of the multi-wavelength optical amplifier, and the initial value of the slope control power Pase(Total)c when performing ASE power spectrum control on the multi-wavelength optical amplifier; in addition, for a VGA-type multi-wavelength optical amplifier, it is also necessary to determine the attenuation setting value ATT(set) of the multi-wavelength amplifier with VOA, and the attenuation setting initial value ATT(set)c of the multi-wavelength amplifier with VOA.

[0133] In specific implementation, the target power slope PowerTilt of the multi-wavelength optical amplifier can be selected according to actual needs, that is, according to the setting value of the working scene of the multi-wavelength optical amplifier. As for the attenuation setting initial value ATT(set)c of the multi-wavelength optical amplifier with VOA, it can be known from the above description that when the gain control parameter of the multi-wavelength optical amplifier is obtained, the attenuation setting initial value ATT(set)c can be determined. According to the demand for ASE power spectrum control of the multi-wavelength optical amplifier, the attenuation setting value ATT(set) of the multi-wavelength amplifier with VOA can be configured, that is, the attenuation setting value ATT(set) of the multi-wavelength amplifier with VOA can be selected and set according to experience.

[0134] The following is an example of how to determine the initial value PowerTiltc of the power slope of the multi-wavelength optical amplifier and how to determine the initial value Pase(Total)c of the slope control power when performing power slope control on the multi-wavelength optical amplifier.

[0135] Specifically, for the multi-wavelength optical amplifier, a target power is determined when the multi-wavelength optical amplifier performs ASE power spectrum control, and the determined target power configuration is used as an initial value Pase(Total)c of the slope control power;

[0136] The multi-wavelength optical amplifier is tested to obtain corresponding test points, and linear fitting is performed on the obtained test points to obtain a power slope fitting line.

[0137] Based on the power slope fitting line obtained by linear fitting, the fitted power slope can be obtained, and the obtained fitted power slope is configured as the power slope initial value PowerTiltc of the multi-wavelength optical amplifier.

[0138] Figure 5 An embodiment of the power slope fitting line of the present invention is shown in FIG. 1 , in which the horizontal axis is wavelength, in nm; the vertical axis is power spectrum density, in dB / nm; specifically, for a multi-wavelength optical amplifier, the above method can be used to determine the target power when the multi-wavelength optical amplifier performs ASE power spectrum control. After determining the target power, the target power can be determined as the initial value Pase(Total)c of the slope control power.

[0139] When the ASE power output by the multi-wavelength optical amplifier is adjusted to be consistent with the target power, the current working parameters of the multi-wavelength optical amplifier are maintained and test fitting is performed, wherein the current working parameters of the multi-wavelength optical amplifier are the working parameters when the ASE power output by the multi-wavelength optical amplifier reaches the target power. Figure 5 It can be seen that when testing the fitting, a spectrometer can be used to scan the ASE power spectrum density of the multi-wavelength optical amplifier to determine the corresponding test point. For example, the black dot in 5 is the test point, and multiple test points can be obtained in the same way.

[0140] Linear fitting is performed for multiple test points, and the linear fitting method can be least square fitting, and after fitting, a power slope fitting line is obtained. Figure 5 The oblique line surrounded by the black dots in the figure is the power slope fitting line. Figure 5 In the figure, the height difference of the power slope fitting line is the fitted power slope, that is, Figure 5 The Power Tilt in is the fitted power slope. In one embodiment of the present invention, the fitted power slope is configured as the power slope initial value PowerTiltc.

[0141] It can be seen from the above description that when the target power is determined as the initial value of the slope control power Pase(Total)c, the initial value of the slope control power Pase(Total)c and the gain tilt setting value (gain tilt(set)) of the multi-wavelength optical amplifier are basically the same. This is because: at this time, the ASE power spectrum shape of the multi-wavelength optical amplifier and the gain curve shape under the gain setting value Gain(set) are basically consistent, and their flatness index and slope index can be basically considered to be equivalent to each other.

[0142] The above gives a method for determining the initial value Pase(Total)c of the slope control power and the initial value PowerTiltc of the power slope. Of course, other methods can also be used, which can be selected according to needs, and no examples are given here. It can be seen from the above description that after determining the initial value Pase(Total)c of the slope control power and the initial value PowerTiltc of the power slope, the power slope of the multi-wavelength optical amplifier can be controlled.

[0143] From the above description, it can be seen that the multi-wavelength optical amplifier can have multiple feasible application scenarios. Figure 6 FIG. 1 shows an embodiment of a multi-wavelength optical amplifier applied to a multi-wavelength multi-span optical transmission system. In the figure, the multi-wavelength multi-span optical transmission system includes a plurality of multi-wavelength optical amplifiers cascaded in sequence. In the figure, OA1 is a multi-wavelength optical amplifier, and the multi-wavelength optical amplifier OA1 is connected to the optical fiber 1. Similarly, OA2 is a multi-wavelength optical amplifier, and the multi-wavelength optical amplifier OA2 is connected to the optical fiber 2. The same applies to other cases. Figure 6 The number of multi-wavelength optical amplifiers can be selected according to the needs, so as to meet the actual application requirements of the multi-wavelength and multi-span optical transmission system. Figure 6 In the figure, the input end of OA1 is connected to a receiving multiplexer, through which an optical signal can be received. Tx1~Txn are optical signals loaded into the receiving multiplexer. Optical fiber n is connected to a demultiplexer, through which multiple transmission optical signals can be obtained. Rx1~Rxn are optical signals output by the demultiplexer.

[0144] For the above-mentioned multi-wavelength multi-span optical transmission system, any node may be in a state where the multi-wavelength optical amplifier has no input signal due to factors such as cutover or fiber break, that is, there may be a state where the input light is disconnected, such as the input and output ends of OA1; the input and output ends of OA2; and / or the input end of OAn may all be in a state where the input light is disconnected.

[0145] It can be seen from the above description that when the multi-wavelength optical amplifier of any node is in the input light disconnected state, and the multi-wavelength optical amplifiers after the node are in the normal state, it is necessary to adjust the ASE power spectrum of the multi-wavelength optical amplifier of the current node. For example, when the input light of OA1 is disconnected and other subsequent multi-wavelength optical amplifiers remain in the normal state, by adjusting the ASE power spectrum of the multi-wavelength optical amplifier where OA1 is located, the normal operation of other multi-wavelength optical amplifiers can be guaranteed (the ASE power output by the multi-wavelength optical amplifier where OA1 is located is used as the signal power). When the line is restored, the control of all multi-wavelength optical amplifiers will be quickly controlled according to the input power size without reopening the pump laser from no output to output control. All multi-wavelength optical amplifier control states will not change due to reopening, re-debugging is simple, and transient effects are not obvious.

[0146] Based on the above description, the method for controlling the ASE power spectrum of any multi-wavelength optical amplifier includes:

[0147] Determine whether the input light of the current multi-wavelength optical amplifier is disconnected? If disconnected (under the condition of no input light), the above steps of ASE power spectrum control for the multi-wavelength optical amplifier can be performed, wherein whether the input light of the multi-wavelength optical amplifier is disconnected can refer to the above description for specific judgment instructions.

[0148] Obtaining a gain control parameter of a multi-wavelength optical amplifier, wherein the gain control parameter at least includes a gain setting value Gain(set);

[0149] Based on the acquired gain control parameters, a typical noise figure NF spectrum line and a gain curve of the multi-wavelength optical amplifier under the gain control parameters are acquired;

[0150] Based on the typical noise figure NF spectrum and gain curve obtained, the target power for ASE power spectrum control of the multi-wavelength optical amplifier is configured;

[0151] Configure the working state of the multi-wavelength optical amplifier based on the target power, and make the ASE power output by the multi-wavelength optical amplifier consistent with the target power;

[0152] When the power slope of the multi-wavelength optical amplifier needs to be further adjusted, the power slope of the multi-wavelength optical amplifier can be adjusted according to formula (5), specifically, the target power slope PowerTilt of the multi-wavelength optical amplifier can be obtained.

[0153] When the above EDFA multi-wavelength optical amplifier is regulated, the EDFAs at other nodes remain in working state unchanged;

[0154] Real-time determination of whether the input of the EDFA multi-wavelength optical amplifier of the current node has returned to normal. If it has returned to normal, the EDFA will automatically return to its original working state.

[0155] In specific implementation, when the above method is used to control the ASE power spectrum of a multi-wavelength optical amplifier, the waveform of the ASE power spectrum can be made close to the waveform of the gain curve of the multi-wavelength optical amplifier, or an ASE power spectrum with a specific power slope can be obtained. The other subsequent multi-wavelength optical amplifiers can remain in normal working condition, which can improve the recovery efficiency of the multi-wavelength and multi-span optical transmission system and reduce the impact of transient effects.

[0156] Furthermore, before disconnecting the input light, each node is equipped with an OCM (optical channel monitor) device, which can be used to monitor the actual wavelength and power of the optical signal of each node. At this time, the ASE power spectrum of the current node can be directly adjusted according to the actual power spectrum of the monitored optical signal according to formula (5) to maintain a consistent power slope. At this time, the setting parameters of the entire multi-wavelength optical transmission system (wss setting parameters, Gain parameters, etc.) can be kept unchanged to the greatest extent possible.

[0157] As can be seen from the above description, a multi-wavelength optical amplifier can also be used to generate filler waves. Specifically, when the multi-wavelength optical amplifier is in cascade debugging of multi-wavelength optical transmission, one multi-wavelength optical amplifier is configured as an ASE light source, and the optical amplifier cascaded with the ASE light source is used as a debugging optical amplifier;

[0158] When generating a fill wave for debugging an optical amplifier based on an ASE light source, the following steps are included:

[0159] Determine the optical input power range of the debugging optical amplifier, and configure the target power output by the ASE light source, wherein the target power is adapted to the optical input power range of the debugging optical amplifier;

[0160] The working state of the ASE light source is configured based on the target power, and the ASE power of the ASE light source is made consistent with the target power, and the ASE power output by the ASE light source is used as a fill wave for debugging the optical amplifier.

[0161] It can be seen from the above description that when performing cascade testing, an ASE light source can be used to generate fill waves, thereby reducing complexity and cost. Figure 7 and Figure 8 FIG. 1 shows an implementation case of using an ASE light source to generate fill-in waves and perform cascade debugging. In the figure, during the cascade test, at least two multi-wavelength optical amplifiers are included. The two multi-wavelength optical amplifiers are in a cascade state. Figure 7 In the embodiment, a multi-wavelength optical amplifier is formed based on OAA1, and another multi-wavelength optical amplifier is formed based on OAA2, wherein the multi-wavelength optical amplifier formed based on OAA1 is cascaded with the multi-wavelength optical amplifier formed based on OAA2; Figure 8 In the embodiment, a multi-wavelength optical amplifier is formed based on OAA3, and another multi-wavelength optical amplifier is formed based on OAA4, wherein the multi-wavelength optical amplifier formed based on OAA3 is cascaded with the multi-wavelength optical amplifier formed based on OAA4.

[0162] For two cascaded multi-wavelength optical amplifiers, one of them is used as an ASE light source, and the other is used as a debugging optical amplifier. Figure 7 The multi-wavelength optical amplifier formed based on OAA1 is used as the ASE light source, and the multi-wavelength optical amplifier formed based on OAA2 is used as the debugging optical amplifier. Figure 8 In the example, the multi-wavelength optical amplifier formed based on OAA3 is used as the ASE light source, and the multi-wavelength optical amplifier formed based on OAA4 is used as the debugging optical amplifier. During cascade debugging, the ASE light source is used to generate the fill wave required for debugging the optical amplifier. Therefore, the target power can be set according to the debugging optical amplifier, where the target power is generally any power within the optical input power range of the debugging optical amplifier. When the ASE power generated by the ASE light source is consistent with the target power, it can meet the requirements of being a fill wave.

[0163] Specifically, Figure 7 In the WSS+OA board, the multi-wavelength optical amplifier OAA1 and the multi-wavelength optical amplifier OAA2 are used to realize the regulation of the ASE power spectrum, that is, to meet the needs of ASE filling waves, that is, to regulate the specific wavelength required by WSS2 and the power corresponding to the wavelength. Figure 8 In the example, it is only an OA board, which can only realize the ASE power spectrum, and needs to use external WSS to realize the regulation of specific wavelength and the power corresponding to the wavelength.

[0164] Therefore, when using ASE light source to generate fill wave and perform cascade debugging, the specific method can be:

[0165] The multi-wavelength optical amplifier EDFA1 does not receive any input signal.

[0166] Obtaining a gain control parameter of the multi-wavelength optical amplifier EDFA1, wherein the gain control parameter at least includes a gain setting value Gain (set);

[0167] Based on the acquired gain control parameters, a typical noise figure NF spectrum line and a gain curve of the multi-wavelength optical amplifier under the gain control parameters are acquired;

[0168] The above-mentioned ASE power spectrum control and power slope control are performed on the multi-wavelength optical amplifier EDFA1. During the power slope control, the target slope control power Pase(total)2 under the optimal flatness condition is calculated, and the ASE power output by the multi-wavelength optical amplifier EDFA1 is controlled to the target slope control power Pase(total)2.

[0169] If the target slope control power Pase(total)2 is too large or too small and does not meet the input power requirement of the multi-wavelength optical amplifier EDFA2, the gain control setting Gain(set) in the multi-wavelength optical amplifier EDFA1 can be changed to adjust the target value of Pase1(total).

[0170] The output of the multi-wavelength optical amplifier EDFA1 (i.e., Pase(total)2) is used as the input of the multi-wavelength optical amplifier EDFA2. According to actual needs, the output of the multi-wavelength optical amplifier EDFA2 is used as the target filling wave. Generally, the target filling wave power needs to be greater than 20dBm (4dBm / nm). At this time, for the multi-wavelength optical amplifier EDFA2, the input power is normal, and it only needs to be controlled according to the conventional gain. After that, the multi-wavelength optical amplifier EDFA2 is connected to the WSS device to select and control the filling wave filter. At this point, the filling ASE control in the transmission system is completed.

[0171] From the above description, an ASE power spectrum control system of an optical amplifier can be obtained. In one embodiment of the present invention, it includes a power spectrum control device, wherein, for any multi-wavelength optical amplifier, when the multi-wavelength optical amplifier is in an input light disconnected state, the power spectrum control device uses the above-mentioned ASE power spectrum control method to perform ASE power spectrum control on the multi-wavelength optical amplifier so that the shape of the ASE power spectrum is close to the shape of the gain curve of the multi-wavelength optical amplifier.

[0172] Specifically, the power spectrum control device can adopt the existing commonly used ones, such as the PD detector mentioned above, and the type of the power spectrum control device can be selected according to actual needs, so as to meet the needs of ASE power spectrum control. When the power spectrum control device performs ASE power spectrum control on the multi-wavelength optical amplifier, the specific control method and process can refer to the above description, which will not be repeated here.

[0173] In summary, for any multi-wavelength optical amplifier, the ASE power spectrum of the multi-wavelength optical amplifier can be quickly controlled, and the shape of the ASE power spectrum can be made close to the shape of the gain curve under normal gain control. The multi-wavelength optical amplifier can also be quickly configured for power slope control, so that the ASE power output by the multi-wavelength optical amplifier is the target slope control power Pase (total) 2, and no additional ASE light source is required. Based on the control of the multi-wavelength optical amplifier, the ASE output and fill wave of the target slope control power Pase (total) 2 can be quickly achieved, without the need for special board preparation, which greatly saves preparation time and cost.

[0174] For multi-stage transmission systems with multi-wavelength optical amplifier equipment, when there is no input at a certain site, an ASE output spectrum with a specific power slope can be quickly realized to ensure the stability of the system when there is no signal light input. When the system recovers, it can quickly achieve normal working status and reduce transient and unstable effects caused by mode switching, system parameter readjustment, etc.

Claims

1. A method for controlling the ASE power spectrum of an optical amplifier, characterized in that: The method is used to control the ASE power spectrum output by a multi-wavelength optical amplifier with input light disconnected, and make the waveform of the ASE power spectrum close to the waveform of the gain curve of the multi-wavelength optical amplifier, wherein the ASE power spectrum control method comprises: Obtaining a gain control parameter of the multi-wavelength optical amplifier during normal gain control; Based on the acquired gain control parameters, a typical noise figure NF spectrum line and a gain curve of the multi-wavelength optical amplifier under the gain control parameters are acquired; Based on the typical noise figure NF spectrum and gain curve obtained, the target power for ASE power spectrum control of the multi-wavelength optical amplifier is configured; Configure the working state of the multi-wavelength optical amplifier based on the target power, and make the ASE power output by the multi-wavelength optical amplifier consistent with the target power; When the ASE power spectrum output by the multi-wavelength optical amplifier has a power slope, it is also necessary to perform power slope control on the ASE power spectrum output by the multi-wavelength optical amplifier. When configuring the power slope of the multi-wavelength optical amplifier, there are: PowerTilt=PowerTiltc+k1*[Pase(total)2-Pase(total)c]+k2*[ATT(set)-ATT(set)c] Wherein, PowerTilt is the target power slope of the multi-wavelength optical amplifier, PowerTiltc is the initial value of the power slope of the multi-wavelength optical amplifier, Pase(Total)c is the initial value of the control power when the power slope of the multi-wavelength optical amplifier is controlled, ATT(set)c is the initial value of the attenuation setting of the multi-wavelength optical amplifier with VOA, Pase(total)2 is the target slope control power after the power slope of the multi-wavelength optical amplifier is controlled, the unit of the slope control power Pase(total)2 is dBm, ATT(set) is the attenuation setting value of the multi-wavelength optical amplifier with VOA, k1 and k2 are both calibration coefficients. For FGA type multi-wavelength optical amplifiers, ATT(set)-ATT(set)c is 0.

2. The ASE power spectrum control method of an optical amplifier according to claim 1, characterized in that: The target power when performing ASE power spectrum control on the multi-wavelength optical amplifier is generated based on the target reference power, where: The target reference power is calculated based on a typical noise figure NF spectrum line and a gain curve.

3. The method for controlling the ASE power spectrum of an optical amplifier according to claim 2, wherein: For the target reference power, we have: Wherein, Pase(Total) is the target reference power, ν is the frequency of the input light when the multi-wavelength optical amplifier is working, and the unit is Hz, h is the Planck constant, v1 is the starting frequency at which the multi-wavelength optical amplifier can amplify the optical signal, v2 is the ending frequency at which the multi-wavelength optical amplifier can amplify the optical signal, and the ending frequency v2 is greater than the starting frequency v1, NF(ν) is the typical noise index value determined based on the typical noise index NF spectrum line at the frequency ν, and G(ν) is the gain value determined based on the gain curve at the frequency ν.

4. The method for controlling the ASE power spectrum of an optical amplifier according to claim 2, wherein: For the target reference power, we have: Pase(Total)=NF ave *G ave *hν ave (ν2-ν1) Among them, Pase(Total) is the target reference power, NF ave is the average value of the typical noise index NF spectrum, G ave is the average gain of the gain curve, v1 is the starting frequency of the optical signal that the multi-wavelength optical amplifier can amplify, v2 is the ending frequency of the optical signal that the multi-wavelength optical amplifier can amplify, ν ave is the center frequency, center frequency ν ave It is the average value of the starting frequency ν1 and the ending frequency ν2. The ending frequency v2 is greater than the starting frequency v1. h is Planck's constant.

5. The method for controlling the ASE power spectrum of an optical amplifier according to claim 3, wherein: When the multi-wavelength optical amplifier has a GFF, the target power of the multi-wavelength optical amplifier is the sum of the target reference power and the control compensation value, wherein: The control compensation value is 10*log (GFF bandwidth / amplifier bandwidth), wherein the GFF bandwidth is the working bandwidth of the GFF, the amplifier bandwidth is the effective bandwidth of the multi-wavelength optical amplifier, and log is a logarithmic operation with 10 as the base.

6. The method for controlling the ASE power spectrum of an optical amplifier according to claim 1, wherein: Obtaining gain control parameters of the multi-wavelength optical amplifier, including at least a gain setting value Gain(set); Configuring the working state of the multi-wavelength optical amplifier and making the ASE power of the multi-wavelength optical amplifier consistent with the target power includes: For multiple pump sources in the multi-wavelength optical amplifier, the pump powers of the pump sources are adjusted, and the ratio of the adjusted pump powers of the multiple pump sources remains unchanged, so that the pump power ratio of the multiple pump sources remains consistent with the pump power ratio of the pump sources during normal gain control under typical minimum input conditions.

7. The method for controlling the ASE power spectrum of an optical amplifier according to claim 1, wherein: When the multi-wavelength optical amplifier includes a VOA, the acquired gain control parameter of the multi-wavelength optical amplifier also includes an attenuation value ATT(set) of the VOA, where: When configuring the working state of the multi-wavelength optical amplifier, keep the attenuation value ATT(set) of the VOA unchanged.

8. The method for controlling the ASE power spectrum of an optical amplifier according to any one of claims 1 to 7, characterized in that: When obtaining a typical noise index NF spectrum line under the gain control parameter, the noise index NF spectrum line of the multi-wavelength optical amplifier under typical input light and typical output light power is configured as the typical noise index NF spectrum line.

9. An ASE power spectrum control system for an optical amplifier, characterized in that: It comprises a power spectrum control device, wherein, for any multi-wavelength optical amplifier, when the multi-wavelength optical amplifier is in an input light disconnected state, the power spectrum control device uses the ASE power spectrum control method described in any one of claims 1 to 8 to control the multi-wavelength optical amplifier so that the shape of the ASE power spectrum is close to the shape of the gain curve of the multi-wavelength optical amplifier.

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