Apparatus and method for determining optical phase difference of sub-signal of optical transmitter

Abstract

To provide an apparatus and a method for determining an optical phase difference of a sub-signal of an optical transmitter.SOLUTION: A method includes: inputting a first input signal to a first electrical / optical conversion unit, to enable the first electrical / optical conversion unit to modulate to-be-modulated light on the basis of the first input signal to obtain a first output signal; inputting a second input signal to a second electrical / optical conversion unit, to enable the second electrical / optical conversion unit to modulate to-be-modulated light on the basis of the second input signal to obtain a second output signal, with a correlation value of the second input signal and the first input signal being not 0; performing a coherent detection operation on the basis of the first output signal and the second output signal to obtain a first output amount and a second output amount; and determining an optical phase difference between an output signal of the first electrical / optical conversion unit and an output signal of the second electrical / optical conversion unit on the basis of the first output amount and the second output amount.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the technical field of optical communication.

Background Art

[0002] In the field of optical communication, in order to achieve a larger communication capacity, the rate of the signal output from the transmitter is very high, for example, 100 Gbaud. These signals often consist of a plurality of sub-signals. For example, a dual-polarization system has two polarization components of x and y, a coherent system has an in-phase component I and a quadrature component Q, under the architecture of a DAC, PAM8 is a superposition of 0 / 1 sequences of 3 paths, and the 0 / 1 sequence of each path constitutes a sub-signal of one path. In the case of multi-segment modulation, the total signal is a superposition of each modulation segment signal, and each modulation segment constitutes a sub-signal of one path. From the perspective of hardware implementation, since these sub-signals are often generated by different electrical components and optical components, different sub-signals may have different analog characteristics. For example, different sub-signals may have different optical phases. In certain cases, it is necessary to satisfy a predetermined relationship between the optical phases of these sub-signals. For example, in a coherent transmitter, the optical phase difference between the in-phase component and the quadrature component needs to be 90 degrees, and the optical phase difference between the in-phase superposed sub-signals needs to be 0 degrees.

[0003] It should be noted that the introduction of the above background art is for clearly and completely explaining the technical solution of the present invention and for easy understanding by those skilled in the art. These technical solutions should not be construed as well-known to those skilled in the art just because they are described in the background art of the present invention.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the inventors have discovered the following. That is, in certain cases, when the necessary phase relationship between the optical phases of the sub-signals of the optical transmitter is not satisfied, the output signal of the optical transmitter may be distorted or interference may occur between different sub-signals, so that the performance of the communication system will deteriorate. Therefore, it is highly necessary to monitor the phase difference between each sub-signal in the optical transmitter. However, at present, there is still no simple and feasible method for estimating the optical phase difference between the sub-signal and the reference signal and between each sub-signal.

[0005] In view of at least one of the above problems, embodiments of the present invention provide an apparatus and method for determining the optical phase difference of an optical transmitter sub-signal (i.e., the optical phase difference of the sub-signal of the optical transmitter). By using the coherence detection amount of a high-speed sub-signal and another high-speed signal in the communication process of the optical transmitter, the optical phase difference of the optical transmitter or the electro-optical conversion unit of the optical transmitter is indicated, which is simple to implement, has a flexible implementation method, and a wide application range.

Means for Solving the Problem

[0006] According to one aspect of an embodiment of the present invention, there is provided an apparatus for determining the optical phase difference of a sub-signal of an optical transmitter, the apparatus comprising: A first signal input unit for inputting a first input signal to a first electro-optical conversion unit, so that the first electro-optical conversion unit modulates the optical signal to be modulated based on the first input signal to obtain a first output signal; A second signal input unit for inputting a second input signal to a second electro-optical conversion unit, so that the second electro-optical conversion unit modulates the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not zero; A low-speed coherence detection unit for performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output amount and a second output amount; and It includes a optical phase difference determination unit for determining an optical phase difference between an output signal of the first electro-optical conversion unit and an output signal of the second electro-optical conversion unit based on the first output power and the second output power.

[0007] Moreover, according to another aspect of an embodiment of the present invention, a method for determining an optical phase difference of a sub-signal of an optical transmitter is provided. The method includes: Inputting a first input signal into a first electro-optical conversion unit, so that the first electro-optical conversion unit modulates light to be modulated based on the first input signal to obtain a first output signal; Inputting a second input signal into a second electro-optical conversion unit, so that the second electro-optical conversion unit modulates light to be modulated based on the second input signal to obtain a second output signal, and a correlation value between the second input signal and the first input signal is not zero; Performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and Determining an optical phase difference between an output signal of the first electro-optical conversion unit and an output signal of the second electro-optical conversion unit based on the first output power and the second output power.

Advantages of the Invention

[0008] The advantageous effects of the embodiments of the present invention are at least as follows. That is, the present invention determines the optical phase difference by using signals output from the electro-optical conversion units of the optical transmitter, and the optical transmitter does not need to transmit special signals, so the implementation is simple. The present invention can realize the monitoring of the optical phase differences of the sub-signals of the optical transmitter by using low-speed electrical devices, can avoid the use of high-speed devices, and since the low-speed electrical devices can be installed in an integrated or non-integrated manner, the implementation method is flexible. In addition, the present invention can be applied to the monitoring of the optical phase differences of sub-signals in multiple types of optical transmitters, so the applicable scenarios are rich.

[0009] Note that terms such as "comprising / including" when used in this specification refer to the presence of features, elements, steps, or assemblies, but also refer to the fact that the presence or addition of one or more other features, elements, steps, or assemblies is not excluded.

Brief Description of the Drawings

[0010] The elements and features described in one drawing or one embodiment of the present invention can be combined with the elements and features shown in one or more other drawings or embodiments. Also, in the drawings, like reference numerals indicate corresponding parts in several drawings and are also used to indicate corresponding parts used in a plurality of embodiments.

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

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Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 7

Figure 8

Figure 9

Figure 10A

Figure 10B

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0011] By referring to the accompanying drawings and the following description, the foregoing and other features of the present invention will become apparent. Although specific embodiments of the present invention are disclosed in the specification and drawings, they are only examples showing some of the embodiments that can adopt the principles of the present invention. It should be understood that the present invention is not limited to the described embodiments, that is, the present invention also includes all changes, modifications, and substitutions belonging to the scope of the appended patent claims.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] <Embodiments of the First Aspect> In an embodiment of the present invention, a method for determining the optical phase difference of sub-signals of an optical transmitter is provided. FIG. 1 is a diagram showing the method for determining the optical phase difference of sub-signals of an optical transmitter in an embodiment of the present invention. As shown in FIG. 1, the method includes the following operations (steps).

[0014] 101: By inputting a first input signal into a first electro-optical conversion unit, the first electro-optical conversion unit is caused to modulate the optical signal to be modulated based on the first input signal to obtain a first output signal; 102: By inputting a second input signal into a second electro-optical conversion unit, the second electro-optical conversion unit is caused to modulate the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not 0; 103: Performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output amount (output value) and a second output amount (output value); and 104: Determining the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit based on the first output amount and the second output amount.

[0015] It should be noted that the above-mentioned FIG. 1 is for illustrative purposes of an embodiment of the present invention, but the present invention is not limited thereto. For example, some of the above steps can be executed simultaneously, sequentially, the execution order between each operation can be appropriately adjusted, or several operations can be increased or decreased. In addition, those skilled in the art can appropriately modify the above content without being limited to the description of FIG. 1 above.

[0016] In step 101, by inputting a first input signal into a first electro-optical conversion unit, the first electro-optical conversion unit is caused to modulate the optical signal to be modulated based on the first input signal to obtain a first output signal.

[0017] In some embodiments, the first input signal may be any signal. In the present invention, it is represented as the first input signal A[n]. The first input signal A[n] may be a discrete symbol sequence or a continuous signal. Among them, n represents a time series number. Based on the first input signal A[n], the first electro-optical conversion unit modulates the incoming optical signal to be modulated to obtain a first output signal, and the first output signal is a high-speed signal and an optical signal. The optical signal to be modulated is, for example, direct current light or an optical signal output from a higher-level device connected to the first electro-optical conversion unit.

[0018] In some embodiments, the first electro-optical conversion unit is a unit that has a modulation function and can generate a high-speed signal. For example, the first electro-optical conversion unit is the optical transmitter itself. At this time, the first output signal is the total output optical signal of the optical transmitter. The first electro-optical conversion unit may also be a partial modulation segment (also referred to as a modulation unit) of the optical transmitter. At this time, the first output signal is a part of the total output optical signal of the optical transmitter, that is, the first output signal is included in the total output optical signal of the optical transmitter. Among them, the optical transmitter includes, but is not limited to, a coherent transmitter, an intensity modulation transmitter, a phase modulator, a combined signal transmitter based on an optical frequency comb, etc.

[0019] FIG. 2A to FIG. 2D are diagrams showing a first electro-optical conversion unit in an embodiment of the present invention. In FIG. 2A, an IQ modulator with a plurality of sub-signal branches in a coherent transmitter is shown. Both the I path and the Q path of the IQ modulator have a plurality of modulation segments. The first electro-optical conversion unit in FIG. 2A may be any one of the modulation segments in the IQ modulator. For example, it is a modulation segment corresponding to the first symbol sequence A[n] on the I path, that is, the modulation segment into which the first symbol sequence A[n] is input. In FIG. 2B, the first electro-optical conversion unit is a modulation segment corresponding to the first symbol sequence A[n] in a segmented intensity modulator. In FIG. 2C, the first electro-optical conversion unit is a modulation segment corresponding to the first symbol sequence A[n] in a segmented phase modulator. In FIG. 2D, the first electro-optical conversion unit is an EO MOD unit corresponding to the first symbol sequence A[n] in a combined signal transmitter based on an optical frequency comb. In addition to the structures shown in FIGS. 2A to 2D, the first electro-optical conversion unit may adopt other structures, but the present invention is not limited thereto.

[0020] In step 102, by inputting a second input signal to a second electro-optical conversion unit, the second electro-optical conversion unit is caused to modulate the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not zero.

[0021] In some embodiments, the second input signal is a signal whose correlation value with the first input signal is not zero, which is represented as the second input signal B[n] in the present invention, where n represents a time series number. The second electro-optical conversion unit modulates the input optical signal to be modulated based on the second input signal B[n] to obtain a second output signal, and the second output signal is also a high-speed signal and an optical signal. The optical signal to be modulated of the second electro-optical conversion unit may be the same as or different from the optical signal to be modulated corresponding to the first electro-optical conversion unit.

[0022] In some embodiments, the second input signal is the same as the first input signal, that is, B[n]=A[n]. At this time, the correlation value (a value representing the degree of correlation (correlation coefficient)) between the second input signal and the first input signal is the maximum.

[0023] In some embodiments, the second input signal is a weighted sum of the first input signals at a plurality of different times, that is, B[n]=Σ k c i A[n-n i where 1≦i≦k, both i and k are positive integers, n i is an integer, c i is the weight coefficient corresponding to A[n-n i , and when i≠j, n i ≠n j where 1≦j≦k and j is a positive integer.

[0024] For example, assume k = 2, the first input signals A[n] at two different times are represented as A[n - n1] and A[n - n2] respectively, and the corresponding weight coefficients are represented as c1 and c2 respectively, where n1 and n2 are integers and n1≠n2. In this case, the second input signal B[n] is the weighted sum of A[n - n1] and A[n - n2], that is, B[n]=c1A[n-n1]+c2A[n-n2] Since the calculation method of B[n] is the same when k takes other values, the detailed description is omitted here.

[0025] In some embodiments, the second input signal is a symbol sequence of the weighted sum of the first input signals at a plurality of different times, that is, B[n]=sign(Σ k c i A[n-n i ) where 1≦i≦k, both i and k are positive integers, n i is an integer, c i is the weight coefficient corresponding to A[n-n i ​is the weight coefficient corresponding to, and when i≠j, n i ≠n j where 1≦j≦k, j is a positive integer, and sign() is the SIGN function.

[0026] For example, when k = 2, the first input signals A[n] at two different times are represented as A[n - n1] and A[n - n2] respectively, and the corresponding weight coefficients are represented as c1 and c2 respectively, where n1 and n 2 are integers and n1≠n2, and the SIGN function is sign(). In this case, the second input signal B[n] is the symbol sequence of the weighted sum of A[n - n1] and A[n - n2], that is, B[n]=sign(A[n - n1]+A[n - n2]) Since the calculation method of B[n] is the same when k takes other values, the detailed description is omitted here.

[0027] In some embodiments, the second input signal is the product of the symbol sequence of the weighted sum of the first input signals at a plurality of different times and a random amplitude sequence, that is, B[n]=Amp[n]*sign(Σ k c i A[n - n i ) where 1≦i≦k, both i and k are positive integers, n i is an integer, c i is the weight coefficient corresponding to A[n - n i , and when i≠j, n i ≠n j where 1≦j≦k, j is a positive integer, sign() is the SIGN function, and Amp[n] is a random amplitude sequence.

[0028] For example, assume k = 2, the first input signal A[n] at two different times is represented as A[n - n1] and A[n - n2] respectively, and the corresponding weight coefficients are represented as c1 and c2 respectively, where n1 and n2 are integers and n1 ≠ n2, the SIGN function is sign(), and the random amplitude sequence is Amp[n]. In this case, the second input signal B[n] is the product of the symbol sequence of the weighted sum of A[n - n1] and A[n - n2] and Amp[n], that is, B[n]=Amp[n]*sign(A[n - n1]+A[n - n2]) where Amp[n] can be an amplitude sequence with finite values or an amplitude sequence with infinite values. Amp[n] is, for example, a random amplitude sequence of a series of positive values.

[0029] In some embodiments, the second input signal has a finite number of values. For example, the value set of the second output signal can be {1, -1}, {1, 0}, {1, 0, -1}, etc. The second input signal with a finite number of values can be realized in the following ways.

[0030] For example, when the value of the first input signal is {1, -1}, the second input signal may be the same as the first input signal. At this time, the value of the second input signal is also {1, -1}, or the second input signal may be the weighted sum of the first input signals at multiple different times. At this time, the value of the second input signal is also at a finite number of levels {1, 0, -1}.

[0031] Also, for example, when the value of the first input signal is not {1, -1}, the second input signal may be the SIGN function of the first input signal, whereby a finite number of values of {1, -1} or {1, 0, -1} can be obtained.

[0032] When the value of the second input signal is {1, 0, -1}, but the input of the second electro-optical conversion unit can only take two levels, for example, {1, -1}, the signals at all time positions where B[n] = 0 can be replaced with a random sequence with values {1, -1}. Similarly, when the input of the second electro-optical conversion unit can only take {1, 0}, the signals at all time positions where B[n] = -1 can be replaced with a random sequence with values {1, 0}.

[0033] In some embodiments, the second input signal is made to be operated at intervals. Operating at intervals means that the second input signal B[n] is assigned to only a predetermined part of the times, not all times, of the signals input to the second electro-optical conversion unit. In this way, the second input signal B[n] is input to the second electro-optical conversion unit at a predetermined time, and at times other than the predetermined time, a signal of 0 or a signal whose correlation value with the first input signal A[n] is 0 is input to the second electro-optical conversion unit.

[0034] In some embodiments, the predetermined time may be a periodically occurring time, that is, the second input signal is made to be operated at fixed periodic intervals. For example, FIG. 3 is a diagram showing that the second input signal is operated at intervals in an embodiment of the present invention. In FIG. 3, five rows of square grids are shown. Each square grid among the square grids in each row represents one time. One white square grid represents that the signal marked on the left side of the square grids in that row is assigned at the corresponding time. As shown in FIG. 3, the square grids in the first row from the top represent that the first input signal A[n] is input to the first electro-optical conversion unit at all times. The square grids in the second row represent that the second input signal B[n] is input to the second electro-optical conversion unit at all times. The square grids in the third row represent that the second input signal is operated at an interval of a rate of 1 / 2 (Half-assigned B[n]), that is, taking two times as one period, and at one time in each period, the second input signal B[n] is input to the second electro-optical conversion unit. The square grids in the third row represent that the second input signal is operated at an interval of a rate of 1 / 4 (1 / 4-assigned B[n]), that is, taking four times as one period, and at one time in each period, the second input signal B[n] is input to the second electro-optical conversion unit. The square grids in the fifth row represent that the second input signal is operated at an interval of a rate of 1 / 8 (1 / 8-assigned B[n]), that is, taking eight times as one period, and at one time in each period, the second input signal B[n] is input to the second electro-optical conversion unit.

[0035] Note that in actual applications, the length of the period in which the second input signal B[n] is operated at intervals is not limited to the above example.

[0036] In some embodiments, the predetermined time may be a randomly selected time, that is, the second input signal is made to be operated at randomly spaced intervals.

[0037] In some embodiments, the second input signal operated at intervals may be any of the above-described second input signals provided in the present invention.

[0038] In the above embodiments, by causing the second input signal to be operated at intervals, the time when the second input signal is input decreases, and the output power obtained by the coherence detection operation also decreases accordingly. This is advantageous for reducing the power consumption of the operation for determining the optical phase difference of the sub-signal of the optical transmitter.

[0039] In some embodiments, the second electro-optical conversion unit is a unit that has a modulation function and can generate a high-speed signal. In the present invention, the second electro-optical conversion unit may be a conventional electro-optical conversion unit. FIG. 2E is a diagram showing the second electro-optical conversion unit in an embodiment of the present invention. In FIG. 2E, the second electro-optical conversion unit is an MZ modulator (MZM) having one modulation segment. Further, the second electro-optical conversion unit may also be an MZ modulator (MZM) having two equal-length modulation segments, or an electro-absorption modulator (EAM), or a phase modulator (PM), or a structure in which an amplitude modulator (for example, an MZ modulator (MZM) or an electro-absorption modulator (EAM)) and a phase modulator (PM) are connected in series. In addition to the structures of these examples, the second electro-optical conversion unit may adopt other structures, but the present invention is not limited thereto.

[0040] In some embodiments, the second output signal output from the second electro-optical conversion unit is a continuous signal.

[0041] In some embodiments, the output of the second electro-optical conversion unit has a finite number of states, that is, the second output signal output from the second electro-optical conversion unit is a discrete signal with a finite number of values. For example, the value set of the second output signal output from the second electro-optical conversion unit may be {1, -1}, {1, 0}, {1, 0, -1}, etc.

[0042] When the second electro-optical conversion unit outputs only a finite number of states, the second electro-optical conversion unit only requires logical operations, and its complexity, cost, and power consumption can all be reduced.

[0043] In step 103, a coherence detection operation is performed based on the first output signal and the second output signal to obtain a first output power and a second output power.

[0044] In some embodiments, the coherence detection operation is realized by a low-speed coherence detection unit. FIG. 4 is a diagram showing the low-speed coherence detection unit in an embodiment of the present invention. As shown in FIG. 4, the low-speed coherence detection unit includes one phase shifter (φ), one 90-degree frequency mixer (mixer) (90° hybrid), and two balance detectors (BPD (balanced photodetector)), among which the phase shifter (φ) is optional, that is, FIG. 4 may or may not include a phase shifter. In FIG. 4, the low-speed coherence detection unit has two input signals, namely signal 1 and signal 2, and the low-speed coherence detection unit has two output signals, that is, a first output power and a second output power are obtained based on the first output signal and the second output signal. In addition to the structure shown in FIG. 4, the low-speed coherence detection unit may also adopt other structures, but the present invention is not limited thereto.

[0045] In some embodiments, the principle of performing a coherence detection operation on signal 1 and signal 2 input to the low-speed coherence detection unit to obtain a first output power and a second output power is as follows.

[0046] Assume that signal 1 is represented as E1(t), signal 2 is represented as E2(t), and the optical phase difference between signal 1 and signal 2 is φ. After passing through an ideal 90-degree frequency mixer, the output optical signal can be expressed as follows.

[0047]

Equation

[0048]

Equation

[0049]

Equation

[0050] FIG. 5A is a block diagram of a first electro-optical conversion unit, a second electro-optical conversion unit, and a low-speed coherence detection unit provided in an embodiment of the present invention. As shown in FIG. 5A, the first electro-optical conversion unit and the second electro-optical conversion unit are connected in parallel. At this time, by inputting a first input signal, that is, a first symbol sequence A[n], into the first electro-optical conversion unit, the first electro-optical conversion unit modulates the light 1 to be modulated and outputs a first output signal; by inputting a second input signal, that is, a second symbol sequence B[n], into the second electro-optical conversion unit, the second electro-optical conversion unit modulates the light 2 to be modulated and outputs a second output signal; then, the first output signal and the second output signal are respectively input into the low-speed coherence detection unit to perform a coherence detection operation. That is, in this embodiment, one of the signal 1 and the signal 2 input into the low-speed coherence detection unit is the optical signal of the first output signal output from the first electro-optical conversion unit, and the other of the signal 1 and the signal 2 is the optical signal of the second output signal output from the second electro-optical conversion unit. Then, the low-speed coherence detection unit outputs a first output power and a second output power.

[0051] FIG. 5B is a diagram showing a hardware configuration corresponding to the block diagram of FIG. 5A provided in an embodiment of the present invention. The structure includes a first electro-optical conversion unit, a second electro-optical conversion unit, and a low-speed coherence detection unit. Among them, the first electro-optical conversion unit and the second electro-optical conversion unit are connected in parallel. That is, the first electro-optical conversion unit is connected to the first input end of the low-speed coherence detection unit and inputs a first output signal to the first input end. The second electro-optical conversion unit is connected to the second input end of the low-speed coherence detection unit and inputs a second output signal to the second input end. Also, the first electro-optical conversion unit may be any one of the first electro-optical conversion units shown in FIGS. 2A to 2D or other structures, the second electro-optical conversion unit may be the second electro-optical conversion unit shown in FIG. 2E or other structures, and the low-speed coherence detection unit may be the low-speed coherence detection unit shown in FIG. 4 or other structures.

[0052] For example, in the structure shown in FIG. 5B, the first electro-optical conversion unit adopts the structure shown in FIG. 2A, which is part of a transmitter. The second electro-optical conversion unit adopts the structure shown in FIG. 2E, and the low-speed coherence detection unit adopts the structure shown in FIG. 4.

[0053] In FIG. 5B, the modulation-waiting light of both the first electro-optical conversion unit and the second electro-optical conversion unit is DC light. Before the modulator, a part of the DC light (for example, 95%) is passed to the first electro-optical conversion unit, and another part (for example, 5%) is passed to the second electro-optical conversion unit. Among them, since the coherent transmitter forms a plurality of output ports by a beam splitter MMI, the first output signal output by it may be included in the output signal I + jQ of the I + jQ detection end, or may be included in the output signal I - jQ of the I - jQ detection end, or may be included in the output signals of other detection branches. The acquisition of the output signal can be realized by a beam splitter. The beam splitter forms a part of the output signal (for example, 5%) by splitting the output signal and applies it to the present invention. Specifically, the prior art can be referred to. Note that in FIG. 5B, the example that the signal waiting for detection is included in the output signal I - jQ of the I - jQ detection end is taken, but the present invention is not limited thereto.

[0054] After receiving the first output signal and the second output signal, the low-speed coherence detection unit obtains a first output power I1 and a second output power I2 based on the above-mentioned Formulas 1 to 5. Among them, E1(t) and E2(t) in Formulas 1 to 5 are the first output signal and the second output signal, respectively.

[0055] In some embodiments, performing a coherence detection operation based on the first output signal and the second output signal includes performing a coherence detection operation on the product of the first output signal and the second output signal, and a predetermined reference signal to obtain the first output power and the second output power.

[0056] FIG. 6A is another block diagram of the first electro-optical conversion unit, the second electro-optical conversion unit, and the low-speed coherence detection unit provided in the embodiment of the present invention. As shown in FIG. 6A, the first electro-optical conversion unit, the first electro-optical conversion unit, and the second electro-optical conversion unit are connected in series. At this time, by inputting the first input signal, that is, the first symbol sequence A[n], into the first electro-optical conversion unit, the first electro-optical conversion unit modulates the light 3 to be modulated to obtain a first output signal; by inputting the second input signal, that is, the second symbol sequence B[n], into the second electro-optical conversion unit, the second electro-optical conversion unit modulates the light 4 to be modulated to obtain a second output signal. As shown in FIG. 6A, when the output end of the first electro-optical conversion unit and the input end of the second electro-optical conversion unit are connected in series, the light 3 to be modulated may be direct current light, and the light 4 to be modulated includes the signal to be detected output from the first electro-optical conversion unit. Also, when the output end of the second electro-optical conversion unit and the input end of the first electro-optical conversion unit are connected in series (not shown), the light 4 to be modulated may be direct current light, and the light 3 to be modulated includes the related signal output from the second electro-optical conversion unit. The series connection structure formed by connecting the first electro-optical conversion unit and the second electro-optical conversion unit in series outputs the product of the first output signal and the second output signal in the optical domain, that is, the optical signal of the product of the first output signal and the second output signal. Then, the product of the first output signal and the second output signal, and a predetermined reference signal are input into the low-speed coherence detection unit to perform a coherence detection operation. That is, in the embodiment, one of the signal 1 and the signal 2 input into the low-speed coherence detection unit is the optical signal of the product of the first output signal and the second output signal, and the other of the signal 1 and the signal 2 is a predetermined reference signal. Then, the low-speed coherence detection unit outputs a first output amount and a second output amount. Among them, the predetermined reference signal is, for example, direct current light.

[0057] Figure 6B is a diagram showing a hardware configuration corresponding to the block diagram of Figure 6A provided in an embodiment of the present invention. The structure includes a first electro-optical conversion unit, a second electro-optical conversion unit, and a low-speed coherence detection unit. Among them, the first electro-optical conversion unit and the second electro-optical conversion unit are connected in series, and the series connection structure of the first electro-optical conversion unit and the second electro-optical conversion unit is connected to the first input end of the low-speed coherence detection unit, and the product of the first output signal and the second output signal is input to the first input end, and a predetermined reference signal is input to the second input end of the low-speed coherence detection unit. Also, the first electro-optical conversion unit may be any one of the first electro-optical conversion units shown in Figures 2A to 2D or other structures, the second electro-optical conversion unit may be the second electro-optical conversion unit shown in Figure 2E or other structures, and the low-speed coherence detection unit may be the low-speed coherence detection unit shown in Figure 4 or other structures.

[0058] For example, in the structure shown in Figure 6B, the first electro-optical conversion unit adopts the structure shown in Figure 2A, which is part of a transmitter, the second electro-optical conversion unit adopts the structure shown in Figure 2E, and the low-speed coherence detection unit adopts the structure shown in Figure 4.

[0059] In Figure 6B, the modulation-waiting light of both the first electro-optical conversion unit and the second electro-optical conversion unit is DC light. Before the modulator, a part of the DC light (for example, 95%) is passed to the first electro-optical conversion unit, and another part (for example, 5%) is input as a reference signal (signal 2) to the second input end of the low-speed coherence detection unit. Among them, since the coherent transmitter has a plurality of output ports, the detection-waiting signal output by it may be included in the output signal I + jQ of the I + jQ detection end, or may be included in the output signal I - jQ of the I - jQ detection end, or may be included in the output signals of other detection branches. The acquisition of the output signal can be realized by a beam splitter. The beam splitter forms a part (for example, 5%) of it by splitting the output signal and applies it to the present invention. Specifically, the prior art can be referred to. Note that although Figure 6B takes the case where the detection-waiting signal is included in the output signal I - jQ of the I - jQ detection end as an example, the present invention is not limited thereto.

[0060] After receiving the first output signal and the second output signal, the low-speed coherence detection unit obtains a first output power I1 and a second output power I2 based on the above-mentioned formulas 1 to 5. Among them, E1(t) in formulas 1 to 5 is the product of the first output signal and the second output signal, and E2(t) is the predetermined reference signal.

[0061] In step 104, based on the first output power and the second output power, the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit is determined.

[0062] In some embodiments, the first output power and the second output power are substituted into the following formula to obtain the optical phase difference between the first output signal and the second output signal.

[0063] φ = arg(I1 - jI2) (Formula 6) Among them, I1 is the first output power, I2 is the second output power, φ is the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit, and arg(z) is the principal argument angle value of the complex number z.

[0064] Also, according to the above-mentioned formulas 4 and 5, the following formula 7 can be obtained.

[0065]

Number

[0066] As can be seen from the above embodiments, for any combination of the first input signal and the second input signal whose correlation value is not 0, the optical phase difference φ can be obtained by calculating it according to the method for determining the optical phase difference of the sub-signal of the optical transmitter provided by the present invention. FIG. 7 is a curve of the monitored optical phase difference and the calculated optical phase difference provided by the present invention. Shown in FIG. 7 are the monitored optical phase difference when B[n]=A[n], and the curve of the optical phase difference calculated based on the method for determining the optical phase difference of the sub-signal of the optical transmitter in the present invention. As can be seen from FIG. 7, the optical phase difference can be accurately monitored by the method for determining the optical phase difference of the sub-signal of the optical transmitter in the present invention.

[0067] FIG. 8 is a diagram showing the method for determining the optical phase difference of the sub-signal of the optical transmitter in the embodiment of the present invention. As shown in FIG. 8, the method includes the following steps.

[0068] 801: Input the first input signal into the first electro-optical conversion unit, so that the first electro-optical conversion unit modulates the light to be modulated based on the first input signal to obtain a first output signal; 802: Obtain a first product signal by finding the product of the second input signal and the low-frequency square wave; 803: Input the first product signal of the second input signal and the low-frequency square wave into the second electro-optical conversion unit to obtain a second output signal, and the correlation value between the second input signal and the first input signal is not 0; 804: Perform a coherence detection operation based on the first output signal and the first product signal to obtain a first output power and a second output power; 805: Obtain a second product signal by finding the product of the first output power and the low-frequency square wave, and obtain a third product signal by finding the product of the second output power and the low-frequency square wave; and 806: Determine the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit based on the second product signal and the third product signal.

[0069] Note that the above-mentioned FIG. 8 is for illustrative explanation of the embodiments of the present invention, but the present invention is not limited thereto. For example, some of the above steps can be executed simultaneously, sequentially, the execution order between each operation can be appropriately adjusted, or some operations can be increased or decreased. In addition, those skilled in the art can make appropriate modifications based on the above content without being limited to the description of FIG. 8 above.

[0070] In some embodiments, in step 801, the first input signal is the input symbol sequence of the first electro-optical conversion unit, that is, the first input symbol sequence A[n]. The first electro-optical conversion unit is the transmitter itself or a partial modulation segment of the transmitter. The first electro-optical conversion unit has, for example, the structure shown in FIGS. 2A to 2D or other structures. The first output signal is a high-speed signal and an optical signal. Note that for the content regarding the first input signal, the first electro-optical conversion unit, and the first output signal, reference can be made to the implementation of step 101.

[0071] In some embodiments, in step 802, the product of the second input signal and the low-frequency square wave is obtained, which is realized, for example, by a multiplier. FIG. 9 is a diagram showing a part of the hardware configuration for realizing the method shown in FIG. 8 in an embodiment of the present invention. As shown in FIG. 9, the product of the second input signal B[n] and the low-frequency square wave is obtained, and then the product of B[n] and the low-frequency square wave is input to the second electro-optical conversion unit as the symbol sequence of the second electro-optical conversion unit. Note that in FIG. 9, hardware configurations such as the first electro-optical conversion unit, the second electro-optical conversion unit, and the low-speed coherence detection unit are not shown. However, as can be understood by those skilled in the art, FIG. 9 can be combined with the hardware configurations shown in FIGS. 5B and 6B. For example, FIG. 10A is a diagram showing the hardware configuration obtained by combining FIG. 9 and FIG. 5B. FIG. 10B is a diagram showing the hardware configuration obtained by combining FIG. 9 and FIG. 6B. For the description of each hardware configuration in FIG. 10A, reference can be made to FIG. 5B, and for the description of each hardware configuration in FIG. 10B, reference can be made to FIG. 6B, and the detailed description thereof is omitted here.

[0072] In some embodiments, in step 803, the second electro-optical conversion unit may have, for example, the structure shown in FIG. 2E or other structures. The second input signal is also a high-speed signal and an optical signal. For the content related to the second input signal, the second electro-optical conversion unit, and the second output signal, reference may be made to the implementation of step 102.

[0073] In some embodiments, in step 804, a coherence detection operation is performed based on the first output signal and the first product signal to obtain a first output power and a second output power. For the content related to the coherence detection operation, reference may be made to the implementation of step 103.

[0074] In some embodiments, in step 805, the product of the first output power and the low-frequency square wave is obtained to acquire a second product signal, and the product of the second output power and the low-frequency square wave is obtained to acquire a third product signal, which can be realized, for example, by a multiplier. The low-frequency square wave in this step is the same low-frequency square wave as the low-frequency square wave in step 802. For example, as shown in FIGS. 10A and 10B, by connecting one multiplier to each of the two output terminals of the low-speed coherence detection unit, the product of the first output power and the low-frequency square wave, and the product of the second output power and the low-frequency square wave can be realized.

[0075] In some embodiments, in step 806, based on the second product signal and the third product signal, the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit is determined. For the content related to the calculation of the optical phase difference, reference may be made to the implementation of step 104.

[0076] According to the above embodiments, in the present invention, a square-wave multiplication frequency shift (performing frequency shift by multiplying with a square wave) step is added to the method for determining the optical phase difference of the sub-signals of the optical transmitter. That is, the first product signal obtained by obtaining the product of a low-frequency square wave and one symbol sequence is used as the symbol sequence of the second electro-optical conversion unit, and the products of the first output power and the second output power obtained by the coherence detection operation and the low-frequency square wave are obtained respectively to obtain the second product signal and the third product signal, and then, based on the second product signal and the third product signal, the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit is determined. After the square-wave multiplication frequency shift step is added, the calculated first output power and second output power can be shifted from direct current to the frequency of the low-frequency square wave, so that the 1 / f noise near direct current can be avoided.

[0077] As described above, an exemplary description has been given of the method for determining the optical phase difference of the sub-signals of the optical transmitter and some of the hardware configurations for realizing this method, but the present invention is not limited thereto. The method for determining the optical phase difference of the sub-signals of the optical transmitter may further include other steps or processes, and for the specific content of these steps or processes, reference can be made to the prior art. Also, as described above, an exemplary description has been given of the hardware configuration for realizing the method for determining the optical phase difference of the sub-signals of the optical transmitter, but the present invention is not limited to these hardware configurations, and furthermore, appropriate modifications can be made to these configurations. It should be noted that all the implementation manners of these modifications are included in the scope of the embodiments of the present invention.

[0078] The above embodiments are for exemplarily explaining the embodiments of the present invention, but the present invention is not limited thereto, and furthermore, appropriate modifications can be made based on the above embodiments. For example, each of the above embodiments can be used alone, or a plurality of the above embodiments can be combined and used.

[0079] As can be seen from the above embodiments, the present invention determines the optical phase difference using the signal output from the electro-optical conversion unit of the optical transmitter. Since the optical transmitter does not need to transmit a special signal, the implementation is simple. The present invention can realize the monitoring of the optical phase difference of each sub-signal of the optical transmitter using a low-speed electrical device, avoid the use of high-speed devices, and since the low-speed electrical device can be installed in an integrated or non-integrated manner, the implementation method is flexible. In addition, since the present invention can be applied to the monitoring of the optical phase difference of sub-signals in multiple types of optical transmitters, the application scenarios are rich.

[0080] <Embodiment of the second aspect> In the embodiment of the present invention, a device for determining the optical phase difference of the sub-signal of the optical transmitter is provided, and the description of the same content as that of the embodiment of the first aspect is omitted here.

[0081] FIG. 11 is a diagram showing a device for determining the optical phase difference of the sub-signal of the optical transmitter in the embodiment of the present invention. As shown in FIG. 11, the device 1100 for determining the optical phase difference of the sub-signal of the optical transmitter includes the following.

[0082] First signal input unit 1101: It is used to input the first input signal into the first electro-optical conversion unit so that the first electro-optical conversion unit modulates the light to be modulated based on the first input signal to obtain a first output signal; Second signal input unit 1102: It is used to input the second input signal into the second electro-optical conversion unit so that the second electro-optical conversion unit modulates the light to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not 0; Low-speed coherence detection unit 1103: It is used to perform a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and Optical phase difference determination unit 1104: It is used to determine the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit based on the first output power and the second output power.

[0083] In some embodiments, the first electro-optical conversion unit is a transmitter or a modulation segment of a part of the transmitter.

[0084] In some embodiments, the second electro-optical conversion unit outputs a finite number of states.

[0085] In some embodiments, among them, the second input signal is the same as the first input signal; or the second input signal is a weighted sum of the first input signals at a plurality of different times; or the second input signal is a symbol sequence of the weighted sum of the first input signals at a plurality of different times; or the second input signal is a product of a symbol sequence of the weighted sum of the first input signals at a plurality of different times and a random amplitude sequence.

[0086] In some embodiments, the first electro-optical conversion unit and the second electro-optical conversion unit are connected in parallel. The first electro-optical conversion unit is connected to the first input end of the low-speed coherence detection unit 1103 and inputs the first output signal to the first input end. The second electro-optical conversion unit is connected to the second input end of the coherence detection unit and inputs the second output signal to the second input end.

[0087] Also, the low-speed coherence detection unit 1103 is specifically used to perform a coherence detection operation on the first output signal and the second output signal to obtain the first output power and the second output power.

[0088] In some embodiments, the first electro-optical conversion unit and the second electro-optical conversion unit are connected in series. The series connection structure of the first electro-optical conversion unit and the second electro-optical conversion unit is connected to the first input end of the low-speed coherence detection unit 1103, and the product of the first output signal and the second output signal is input to the first input end. A predetermined reference signal is input to the second input end of the low-speed coherence detection unit 1103.

[0089] Specifically, the low-speed coherence detection unit 1103 is used to perform a coherence detection operation on the product of the first output signal and the second output signal and the reference signal to obtain the first output power and the second output power.

[0090] In some embodiments, the optical phase difference determination unit is specifically used to obtain the optical phase difference by substituting the first output power and the second output power into the following formula.

[0091] φ = arg(I1 - jI2) Among them, I1 is the first output power, I2 is the second output power, φ is the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit, and arg(z) is the principal argument value of the complex number z.

[0092] In some embodiments, the apparatus further includes the following (not shown).

[0093] First multiplication unit: It is used to obtain the product of the second input signal and the low-frequency square wave before the second input signal is input to the second electro-optical conversion unit. The two input terminals of the first multiplication unit are respectively input with the second input signal and the low-frequency square wave, and the output terminal of the first multiplication unit is connected to the second signal input unit 1102 and outputs the product of the second input signal and the low-frequency square wave; and Second multiplication unit: It is used to obtain the product of each of the first output power and the second output power and the low-frequency square wave before determining the optical phase difference based on the first output power and the second output power. There are two second multiplication units. Among them, the two input terminals of one second multiplication unit are respectively input with the low-frequency square wave and the first output power output from the optical phase difference determination unit, and the output terminal outputs the product of the first output power and the low-frequency square wave. The two input terminals of the other second multiplication unit are respectively input with the low-frequency square wave and the second output power output from the optical phase difference determination unit, and the output terminal outputs the product of the second output power and the low-frequency square wave.

[0094] Further, the second signal input unit 1102 is further used to input a product signal of the second input signal and the low-frequency square wave to the second electro-optical conversion unit.

[0095] The optical phase difference determination unit 1104 is further used to determine the optical phase based on the product of the first output power and the low-frequency square wave, and the product of the second output power and the low-frequency square wave.

[0096] In some embodiments, the second signal input unit 1102 is further used to input the second input signal to the second electro-optical conversion unit at a predetermined time, and at a time other than the predetermined time, input a signal whose correlation value with the first input signal is not 0, or a signal of 0 to the second electro-optical conversion unit.

[0097] Note that only the components or modules related to the present invention have been described above, but the present invention is not limited thereto. The apparatus 1100 for determining the optical phase difference of the sub-signal of the optical transmitter may further include other components or modules. For the specific content of these components or modules, reference can be made to related technologies.

[0098] For the sake of convenience, only the connection relationship or signal direction between each component or module is shown in FIG. 11. However, as can be understood by those skilled in the art, various related technologies such as bus connection may also be adopted. Further, these components or modules may be implemented by hardware such as a processor and a memory, for example, but the embodiments of the present invention are not limited thereto.

[0099] The above embodiments are for illustrative purposes to explain the embodiments of the present invention, but the present invention is not limited thereto, and appropriate modifications can be made based on the above embodiments. For example, each of the above embodiments may be used alone, or a plurality of the above embodiments may be combined and used.

[0100] As can be seen from the above embodiments, the present invention determines the optical phase difference using the signal output from the electro-optical conversion unit of the optical transmitter. Since the optical transmitter does not need to transmit a special signal, the implementation is simple. The present invention can realize the monitoring of the optical phase difference of each sub-signal of the optical transmitter using a low-speed electrical device, can avoid the use of high-speed devices, and since the low-speed electrical device can be installed in an integrated or non-integrated manner, the implementation method is flexible. Also, since the present invention can be applied to the monitoring of the optical phase difference of sub-signals in multiple types of optical transmitters, the application scenarios are rich.

[0101] <Embodiment of the third aspect> In an embodiment of the present invention, an electronic device is provided, which includes the device 1100 for determining the optical phase difference of the sub-signal of the optical transmitter described in the embodiment of the second aspect, the content of which is incorporated herein. The electronic device may be, for example, a computer, a server, a workstation, a notebook computer, a smartphone, etc., but the embodiments of the present invention are not limited thereto.

[0102] FIG. 12 is a diagram showing an electronic device in an embodiment of the present invention. As shown in FIG. 12, the electronic device 1200 may include a processor (for example, a central processing unit CPU) 1210 and a memory 1220, and the memory 1220 is connected to the central processing unit 1210. Among them, the memory 1220 can store various data, can also store a program 1221 for information processing, and can execute the program 1221 under the control of the processor 1210.

[0103] In some embodiments, the function of the device 1100 for determining the optical phase difference of the sub-signal of the optical transmitter may be integrated into the processor 1210 and realized. Among them, the processor 1210 is configured to realize the method for determining the optical phase difference of the sub-signal of the optical transmitter described in the embodiment of the first aspect.

[0104] In some embodiments, the optical phase difference determination device 1100 for the sub-signals of the optical transmitter is arranged separately from the processor 1210. For example, the optical phase difference determination device 1100 for the sub-signals of the optical transmitter may be configured as a chip connected to the processor 1210, and the function of the optical phase difference determination device 1100 for the sub-signals of the optical transmitter may be realized under the control of the processor 1210.

[0105] For example, the processor 1210 is configured to perform the following control. That is, by inputting the first input signal into the first electro-optic conversion unit, the first electro-optic conversion unit is caused to modulate the optical signal to be modulated based on the first input signal to obtain a first output signal; by inputting the second input signal into the second electro-optic conversion unit, the second electro-optic conversion unit is caused to modulate the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not 0; performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and determining the optical phase difference between the output signal of the first electro-optic conversion unit and the output signal of the second electro-optic conversion unit based on the first output power and the second output power.

[0106] Also, as shown in FIG. 12, the electronic device 1200 may further include an input / output (I / O) device 1230, a display 1240, etc. The functions of these components are the same as those in the prior art, and the detailed description thereof is omitted here. It should be noted that the electronic device 1200 does not necessarily include all the components shown in FIG. 12, and the electronic device 1200 may further include components not shown in FIG. 12. For this, reference may be made to the related art.

[0107] In an embodiment of the present invention, a computer-readable program is further provided. When the program is executed on an electronic device, the program causes the computer to execute the method for determining the optical phase difference of the sub-signals of the optical transmitter described in the embodiment of the first aspect on the electronic device.

[0108] In an embodiment of the present invention, there is further provided a storage medium storing a computer-readable program, wherein the computer-readable program causes a computer to execute a method for determining the optical phase difference of sub-signals of the optical transmitter described in the embodiment of the first aspect in an electronic device.

[0109] In addition, the above-described apparatus and method may be implemented by software or hardware, or may be implemented by a combination of hardware and software. The present invention further relates to a computer-readable program as follows, that is, when the program is executed by a logic component, the logic component realizes the above-described apparatus or component, or the logic component realizes the above-described various methods or steps. The logic component may be, for example, an FPGA (Field Programmable Gate Array), a microprocessor, a processor used in a computer, or the like. The present invention further relates to a storage medium storing the above-described program, such as a hard disk, a magnetic disk, an optical hard disk, a DVD, a flash memory, or the like.

[0110] Furthermore, one or more combinations of the functional blocks described in the drawings and / or one or more combinations of the functional blocks may be realized as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic components, discrete gates or transistor logic components, discrete hardware assemblies, or any other suitable combination for performing the functions described herein. Also, one or more combinations of the functional blocks described in the drawings and / or one or more combinations of the functional blocks may further be configured as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors connected in communication with the DSP, or any other configuration combination.

[0111] In addition, with respect to the above-described embodiments and the like, the following additional remarks are further disclosed.

[0112] (Appendix 1) A method for determining the optical phase difference of a sub-signal of an optical transmitter, comprising: Inputting a first input signal into a first electro-optic conversion unit, so that the first electro-optic conversion unit modulates the optical signal to be modulated based on the first input signal to obtain a first output signal; Inputting a second input signal into a second electro-optic conversion unit, so that the second electro-optic conversion unit modulates the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not zero; Performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and Determining the optical phase difference between the output signal of the first electro-optic conversion unit and the output signal of the second electro-optic conversion unit based on the first output power and the second output power.

[0113] (Appendix 2) The method according to Appendix 1, wherein the first electro-optic conversion unit is a transmitter or a modulation segment of a part of the transmitter.

[0114] (Appendix 3) The method according to Appendix 1, wherein the second electro-optic conversion unit outputs a finite number of states.

[0115] (Appendix 4) The method according to Appendix 1, wherein the second input signal is the same as the first input signal; or the second input signal is a weighted sum of the first input signals at a plurality of different times; or the second input signal is a symbol sequence of a weighted sum of the first input signals at a plurality of different times; or the second input signal is a product of a symbol sequence of a weighted sum of the first input signals at a plurality of different times and a random amplitude sequence.

[0116] (Appendix 5) The method according to Appendix 1, wherein performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power The method includes performing a coherence detection operation on the first output signal and the second output signal to obtain the first output power and the second output power.

[0117] (Appendix 6) The method according to Appendix 1, wherein performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power The method includes performing a coherence detection operation on the product of the first output signal and the second output signal and a predetermined reference signal to obtain the first output power and the second output power.

[0118] (Appendix 7) The method according to Appendix 1, wherein determining an optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit based on the first output power and the second output power The method includes obtaining the optical phase difference by substituting the first output power and the second output power into the following formula: φ = arg(I1 - jI2) where I1 is the first output power, I2 is the second output power, φ is the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit, and arg(z) is the principal argument value of the complex number z.

[0119] (Appendix 8) The method according to Appendix 1, further comprising before inputting the second input signal into the second electro-optical conversion unit, obtaining the product of the second input signal and a low-frequency square wave, and inputting the product signal of the second input signal and the low-frequency square wave into the second electro-optical conversion unit; and Before determining the optical phase difference based on the first output power and the second output power, obtaining the product of each of the first output power and the second output power and the low-frequency square wave, and determining the optical phase based on the product of the first output power and the low-frequency square wave and the product of the second output power and the low-frequency square wave, a method.

[0120] (Appendix 9) The method according to Appendix 1, wherein inputting the second input signal into the second electro-optical conversion unit at a predetermined time, and inputting a signal with a correlation value of 0 with the first input signal, or a signal of 0, into the second electro-optical conversion unit at a time other than the predetermined time, a method.

[0121] (Appendix 10) An electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to execute the computer program to implement a method for determining the optical phase difference of a sub-signal of an optical transmitter described in any one of Appendices 1 to 9, an electronic device.

[0122] (Appendix 11) A storage medium storing a computer-readable program, wherein the computer-readable program causes a computer to execute a method for determining the optical phase difference of a sub-signal of an optical transmitter described in any one of Appendices 1 to 9, a storage medium.

[0123] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such embodiments, and any changes to the present invention belong to the technical scope of the present invention as long as they do not depart from the spirit of the present invention.

Claims

1. An apparatus for determining the optical phase difference of sub-signals of an optical transmitter, comprising: a first signal input unit for inputting a first input signal to a first electro-optical conversion unit, so that the first electro-optical conversion unit modulates the optical signal to be modulated based on the first input signal to obtain a first output signal; a second signal input unit for inputting a second input signal to a second electro-optical conversion unit, so that the second electro-optical conversion unit modulates the optical signal to be modulated based on the second input signal to obtain a second output signal, wherein the correlation value between the second input signal and the first input signal is not zero; a coherence detection unit for performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and an optical phase difference determination unit for determining the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit based on the first output power and the second output power.

2. The apparatus according to claim 1, wherein the first electro-optical conversion unit is a transmitter or a modulation segment of a part of the transmitter.

3. The apparatus according to claim 1, wherein the second electro-optical conversion unit outputs a finite number of states.

4. The apparatus according to claim 1, wherein the second input signal is the same as the first input signal; or the second input signal is a weighted sum of the first input signals at a plurality of different times; or the second input signal is a symbol sequence of a weighted sum of the first input signals at a plurality of different times; or the second input signal is a product of a symbol sequence of a weighted sum of the first input signals at a plurality of different times and a random amplitude sequence.

5. The apparatus according to claim 1, wherein the first electro-optical conversion unit is connected in parallel with the second electro-optical conversion unit, the first electro-optical conversion unit is connected to a first input end of a low-speed coherence detection unit, and inputs the first output signal to the first input end, the second electro-optical conversion unit is connected to a second input end of the low-speed coherence detection unit, and inputs the second output signal to the second input end, and the low-speed coherence detection unit is used to perform a coherence detection operation on the first output signal and the second output signal to obtain the first output power and the second output power.

6. The apparatus according to claim 1, wherein the first electro-optical conversion unit is connected in series with the second electro-optical conversion unit, the series connection structure of the first electro-optical conversion unit and the second electro-optical conversion unit is connected to a first input end of a low-speed coherence detection unit, and the product of the first output signal and the second output signal is input to the first input end, and a predetermined reference signal is input to a second input end of the low-speed coherence detection unit; the low-speed coherence detection unit is an apparatus used to perform a coherence detection operation on the product of the first output signal and the second output signal and the reference signal to obtain the first output amount and the second output amount.

7. The apparatus according to claim 1, wherein the optical phase difference determination unit substitutes the first output amount and the second output amount into a formula φ = arg(I 1 -jI 2 ) to obtain the optical phase difference; Here, I １ is the first output power, I ２ is the second output power, φ is the optical phase difference between the output signal of the first electro-optical conversion unit and the output signal of the second electro-optical conversion unit, and arg(z) is the principal argument angle value of the complex number z, the apparatus.

8. The apparatus according to claim 1, wherein a first multiplication unit for obtaining the product of the second input signal and a low-frequency square wave before inputting the second input signal to a second electro-optical conversion unit; and further includes a second multiplication unit for obtaining the product of each of the first output amount and the second output amount and the low-frequency square wave before determining the optical phase difference based on the first output amount and the second output amount, the second signal input unit is further used to input the product signal of the second input signal and the low-frequency square wave to the second electro-optical conversion unit, the optical phase difference determination unit is further an apparatus used to determine the optical phase difference based on the product of the first output amount and the low-frequency square wave and the product of the second output amount and the low-frequency square wave.

9. The apparatus according to claim 1, wherein the second signal input unit further at a predetermined time, inputs the second input signal to the second electro-optical conversion unit, and at a time other than the predetermined time, inputs a signal with a correlation value of 0 with the first input signal, or a signal of 0, to the second electro-optical conversion unit.

10. A method for determining the optical phase difference of a sub-signal of an optical transmitter, comprising: inputting a first input signal to a first electro-optical conversion unit, so that the first electro-optical conversion unit modulates modulation-waiting light based on the first input signal to obtain a first output signal; By inputting a second input signal into a second electro-optical conversion unit, the second electro-optical conversion unit is caused to modulate light to be modulated based on the second input signal to obtain a second output signal, and the correlation value between the second input signal and the first input signal is not zero; Performing a coherence detection operation based on the first output signal and the second output signal to obtain a first output power and a second output power; and A method comprising determining an optical phase difference between an output signal of the first electro-optical conversion unit and an output signal of the second electro-optical conversion unit based on the first output power and the second output power.

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