Optical signal detection system, optical signal detection device, and optical signal detection method

Abstract

An optical signal detection system (10) is provided with: a non-linear converter (11) for non-linearly converting a predetermined plurality of first optical signals differing in at least one of temporal waveform, intensity, amplitude, and phase into a plurality of second optical signals, and non-linearly converting a third optical signal into a fourth optical signal; a spectrometer (12) for acquiring a plurality of first spectral data items respectively from the plurality of second optical signals, and acquiring third spectral data from the fourth optical signal; and a detecting device (13) for detecting the third optical signal and outputting a detection result. The detecting device (13) is provided with: an analysis unit (131) for performing a sparse principal component analysis on the plurality of first spectral data items to generate a plurality of second spectral data items having fewer frequency components than the plurality of first spectral data items; and a detecting unit (132) for performing comparison between the third spectral data and the plurality of second spectral data items, and detecting the third optical signal on the basis of the result of the comparison.

Description

[Technical Field]

[0001] The present invention relates to an optical signal detection system, an optical signal detection device, and an optical signal detection method for detecting an optical signal by utilizing a nonlinear optical effect. [Background technology]

[0002] Conventionally, there are optical signal detection technologies for detecting the time waveform, intensity, amplitude and phase, etc. of an optical signal. For example, Patent Document 1 discloses a method for reconstructing the time waveform of an input optical signal without using an ultrafast time gate or a reference light source by simulating the propagation of input optical signals of a plurality of intensities in a highly nonlinear optical fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-204308 [Non-patent literature]

[0004] [Non-Patent Document 1] Konishi Sadanori, "Introduction to Multivariate Analysis: From Linear to Nonlinear," Iwanami Shoten, January 2010, pp. 250-258 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques require propagation simulation, which means that it takes a lot of time to detect an optical signal.

[0006] Therefore, the present invention provides an optical signal detection system, an optical signal detection device, and an optical signal detection method that are capable of detecting an optical signal at high speed with a simple configuration. [Means for solving the problem]

[0007] An optical signal detection system according to one aspect of the present invention includes a nonlinear converter that nonlinearly converts a predetermined number of first optical signals, which differ in at least one of time waveform, intensity, amplitude, and phase, into a plurality of second optical signals, and further nonlinearly converts a third optical signal into a fourth optical signal; a spectrometer that acquires a plurality of first spectral data from the plurality of second optical signals, respectively, and further acquires a third spectral data from the fourth optical signal; and a detection device that detects the third optical signal and outputs a detection result, wherein the detection device includes an analysis unit that performs sparse principal component analysis on the plurality of first spectral data to generate a plurality of second spectral data having fewer frequency components than the plurality of first spectral data, and a detection unit that compares the third spectral data with the plurality of second spectral data and detects the third optical signal based on a result of the comparison.

[0008] These comprehensive or specific aspects may be realized as an apparatus, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0009] An optical signal detection system according to an aspect of the present invention can detect an optical signal at high speed with a simple configuration. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram illustrating a functional configuration of an optical signal detection system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating sparse principal component analysis according to the embodiment. [Figure 3] FIG. 3 is a flowchart showing the processing of the analysis phase in the embodiment. [Figure 4] FIG. 4 is a flowchart showing the process of the detection phase in the embodiment. [Figure 5]FIG. 5 is a diagram showing an optical analog / digital conversion system according to the prior art. [Figure 6] FIG. 6 is a diagram illustrating an example in which the optical signal detection system according to the embodiment is applied to optical analog-to-digital conversion. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0012] The embodiments described below are all comprehensive or specific examples, and the numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the scope of the claims.

[0013] In addition, the drawings are not necessarily strict illustrations, and the same reference numerals are used to designate substantially the same components in the drawings, and redundant explanations are omitted or simplified.

[0014] (Embodiment) [1.1 Configuration of the optical signal detection system 10] First, the configuration of an optical signal detection system 10 according to an embodiment will be described with reference to the drawings. Fig. 1 is a block diagram showing the functional configuration of an optical signal detection system 10 according to an embodiment. As shown in Fig. 1, the optical signal detection system 10 according to this embodiment includes a nonlinear converter 11, a spectrometer 12, and a detection device 13.

[0015] The nonlinear converter 11 can nonlinearly convert the optical signal by a nonlinear optical effect, specifically, the nonlinear converter 11 can nonlinearly map the characteristics of the optical signal (e.g., time waveform, intensity, amplitude, phase, or any combination thereof) into a spectral space.

[0016] Generally, linear multivariate analysis methods (such as sparse principal component analysis) cannot be applied to data containing nonlinear structures. Data containing such nonlinear structures can be converted into data to which linear multivariate analysis methods can be applied by mapping them to a high-dimensional space called a feature space using a nonlinear function (see, for example, Non-Patent Document 1).

[0017] The nonlinear converter 11 according to this embodiment corresponds to a physical realization method for converting data into a high-dimensional space using such a nonlinear function. In other words, the nonlinear converter 11 maps the characteristics of an optical signal containing a nonlinear structure into a spectral space (i.e., a high-dimensional space), thereby converting the characteristics of an optical signal to which a linear multivariate analysis method cannot be applied into a spectrum containing multiple frequency components to which the analysis method can be applied.

[0018] For example, a nonlinear optical medium can be used as the nonlinear converter 11. More specifically, a nonlinear optical fiber or a nonlinear optical waveguide (for example, a silicon waveguide) can be used as the nonlinear converter 11, but is not limited to these.

[0019] In this embodiment, the nonlinear converter 11 nonlinearly converts a plurality of first optical signals into a plurality of second optical signals, and further nonlinearly converts a third optical signal into a fourth optical signal.

[0020] The multiple first optical signals are predetermined optical signals having different optical characteristics from one another. Examples of the optical characteristics include at least one of a time waveform, an intensity, an amplitude, and a phase. In this case, the time waveform, an intensity, an amplitude, and a phase of each of the multiple first optical signals are different from the time waveform, an intensity, an amplitude, and a phase of the other first optical signals in at least one of the time waveform, an intensity, an amplitude, and a phase.

[0021] The third optical signal is the optical signal to be detected, i.e., the characteristics of the third optical signal (e.g., temporal waveform, intensity, amplitude and phase, or any combination thereof) are unknown and are to be detected by the optical signal detection system 10.

[0022] The spectrometer 12 can acquire spectral data from the optical signal. For example, a spectrometer using a dispersive element can be used as the spectrometer 12. For example, a diffraction element, a prism, or the like can be used as the dispersive element. Note that the spectrometer 12 is not limited to a spectrometer using a dispersive element, and may be, for example, a spectrometer using an interferometer.

[0023] In this embodiment, the spectrometer 12 obtains a plurality of first spectral data from a plurality of second optical signals, respectively, and further obtains a third spectral data from a fourth optical signal.

[0024] The detection device 13 can detect an optical signal and output a detection result. Detecting an optical signal means detecting an optical characteristic of the optical signal (e.g., a time waveform, intensity, amplitude, and phase, or any combination thereof) and / or detecting information corresponding to the characteristic.

[0025] The detection device 13 may be, for example, a computer having a processor and a memory. In this case, when instructions or software programs stored in the memory are executed by the processor, the computer can function as the detection device 13. Alternatively, the detection device 13 may be a dedicated electronic circuit or the like.

[0026] As shown in FIG. 1, the detection device 13 includes an analysis unit 131 and a detection unit 132. The analysis unit 131 performs sparse principal component analysis on the plurality of first spectral data to generate a plurality of second spectral data having fewer frequency components than the plurality of first spectral data. The number of frequency components included in each of the plurality of second spectral data is fewer than the number of frequency components included in each of the plurality of first spectral data. For example, the analysis unit 131 performs sparse principal component analysis on the plurality of first spectral data, each of which consists of N (N is a natural number greater than or equal to 2) frequency components, to generate a plurality of second spectral data, each of which consists of M (a natural number smaller than N) frequency components. Each of the generated plurality of second spectral data is stored in memory in association with a characteristic (e.g., a time waveform, intensity, amplitude and phase, or any combination thereof) of the corresponding first optical signal.

[0027] Sparse principal component analysis (PCA) is a statistical analysis method that reduces the dimensionality of data by introducing a sparse structure into input variables. In PCA, linear combinations containing only a few input variables can be used as principal components.

[0028] 2 is a diagram illustrating sparse principal component analysis according to an embodiment. In FIG. 2, each line graph represents one piece of spectrum data. In each line graph, the horizontal axis represents wavelength, and the vertical axis represents power value.

[0029] 2A shows a plurality of first spectral data. Each of the plurality of first spectral data represents a spectrum of a plurality of second optical signals. Here, each of the plurality of first spectral data has 1024 frequency components. That is, each of the plurality of first spectral data includes 1024 data points, each of which is formed by a combination of a power value and a frequency. In this case, the frequencies of the 1024 data points are common to the plurality of first spectral data.

[0030] 2(b) shows a plurality of second spectral data. The plurality of second spectral data is generated from the plurality of first spectral data by sparse principal component analysis and can represent the spectral differences of the plurality of second optical signals with fewer frequency components than the plurality of first spectral data. Here, each of the plurality of second spectral data has nine frequency components. That is, each of the plurality of second spectral data includes nine data points, each of which is a combination of a power value and a frequency. In this case, the frequencies of the nine data points are common to the plurality of second spectral data.

[0031] The detector 132 compares the third spectral data with the plurality of second spectral data and detects the third optical signal based on the comparison result. In other words, the detector 132 evaluates the similarity or dissimilarity between the third spectral data and the plurality of second spectral data and detects the third optical signal based on the evaluation result.

[0032] For example, the detecting unit 132 searches for second spectral data similar to the third spectral data by comparing the third spectral data with a plurality of second spectral data, and then detects the third optical signal based on the first optical signal corresponding to the searched second spectral data.

[0033] Alternatively, for example, the detecting unit 132 may compare the third spectral data with a plurality of second spectral data to determine whether or not the plurality of second spectral data includes second spectral data similar to the third spectral data, and then detect the third optical signal based on the determination result.

[0034] The comparison between the third spectral data and the second spectral data can be performed using, for example, the sum of absolute differences (SAD) of frequency components between the third spectral data and the second spectral data. In this case, the detection unit 132 can search for the second spectral data with the smallest SAD among the plurality of second spectral data as the second spectral data most similar to the third spectral data. Furthermore, if the plurality of second spectral data does not include second spectral data with an SAD smaller than a predetermined threshold, the detection unit 132 can determine that there is no second spectral data similar to the third spectral data.

[0035] The comparison method for the second spectral data is not limited to this. For example, instead of SAD, the multiplicative inverse of SAD, the sum of squared differences (SSD), or the inverse of SSD may be used.

[0036] 1.2 Processing of the Optical Signal Detection System 10 The processing of the optical signal detection system 10 configured as above will be described with reference to the drawings. The detection of an optical signal is divided into an analysis phase and a detection phase.

[0037] [1.2.1 Analysis Phase] First, the analysis phase will be described with reference to Fig. 3. Fig. 3 is a flowchart showing the processing of the analysis phase in the embodiment. The analysis phase is performed before the detection phase. However, the analysis phase does not have to be performed for each detection phase.

[0038] First, the nonlinear converter 11 nonlinearly converts a predetermined plurality of first optical signals into a plurality of second optical signals (S100). The plurality of second optical signals are transmitted to the spectrometer 12.

[0039] The spectrometer 12 acquires a plurality of first spectral data from a plurality of second optical signals (S101). Here, each of the plurality of first spectral data includes a relatively large number of frequency components. That is, the spectrometer 12 is required to measure power values ​​at a relatively large number of frequencies. The acquired plurality of first spectral data is transmitted to the detection device 13.

[0040] The analysis unit 131 of the detection device 13 performs sparse principal component analysis on the plurality of first spectral data (S102), thereby generating a plurality of second spectral data that includes fewer frequency components than the plurality of first spectral data.

[0041] The analysis unit 131 of the detection device 13 stores the plurality of second spectral data in association with the plurality of first optical signals (S103). For example, the analysis unit 131 stores a combination of the plurality of second spectral data and the time waveforms, intensities, or amplitudes and phases of the plurality of first optical signals in an internal storage (not shown) of the detection device 13 or an external storage (not shown) connected to the detection device 13.

[0042] [1.2.2 Detection Phase] Next, the detection phase that is performed after the analysis phase will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the processing of the detection phase in this embodiment.

[0043] First, the nonlinear converter 11 nonlinearly converts the third optical signal into a fourth optical signal (S110). The fourth optical signal is transmitted to the spectrometer 12.

[0044] The spectrometer 12 acquires third spectral data from the fourth optical signal (S111). Here, the third spectral data includes at least the same frequency components as the frequency components included in each of the plurality of second spectral data. That is, the spectrometer 12 only needs to measure power values ​​at a relatively small number of frequencies. The acquired third spectral data is transmitted to the detection device 13.

[0045] The detector 132 of the detector 13 compares the third spectral data with the plurality of second spectral data stored in the analysis phase (S112) and detects a third optical signal based on the comparison result (S113). Then, the detector 132 outputs the detection result (S114). Specifically, the detector 132 outputs the detection result to, for example, a storage device, a display, or an information terminal.

[0046] [1.3 Effects, etc.] As described above, the optical signal detection system 10 according to this embodiment includes the nonlinear converter 11 that nonlinearly converts a predetermined number of first optical signals, which differ in at least one of time waveform, intensity, amplitude, and phase, into a plurality of second optical signals, and further nonlinearly converts the third optical signal into a fourth optical signal; the spectrometer 12 that acquires a plurality of first spectral data from the plurality of second optical signals, respectively, and further acquires the third spectral data from the fourth optical signal; and the detection device 13 that detects the third optical signal and outputs the detection result. The detection device 13 includes the analysis unit 131 that performs sparse principal component analysis on the plurality of first spectral data to generate a plurality of second spectral data having fewer frequency components than the plurality of first spectral data, and the detection unit 132 that compares the third spectral data with the plurality of second spectral data and detects the third optical signal based on the comparison result.

[0047] This allows the third optical signal to be detected using the spectrum of the fourth optical signal nonlinearly converted from the third optical signal. That is, the third optical signal can be detected using a nonlinear optical fiber, a nonlinear optical waveguide, or the like, allowing optical signals to be detected with a simple configuration. Furthermore, by using sparse principal component analysis, it is possible to generate a plurality of second spectral data that can express the differences between a plurality of first optical signals using fewer frequency components. Therefore, it is possible to speed up the comparison process of the spectral data.

[0048] Furthermore, for example, in the optical signal detection system 10 according to the present embodiment, the detection unit 132 may search for second spectral data similar to the third spectral data by comparing the third spectral data with a plurality of second spectral data, and detect the third optical signal based on the first optical signal corresponding to the searched second spectral data.

[0049] This makes it possible to search for second spectral data similar to the third spectral data, and to search for nonlinear conversion from the first optical signal to the second optical signal similar to the nonlinear conversion from the third optical signal to the fourth optical signal. Therefore, the first optical signal corresponding to the searched second spectral data can be used to detect the third optical signal, enabling more useful detection of the third optical signal.

[0050] Furthermore, for example, in the optical signal detection system 10 according to the present embodiment, the detection unit 132 may compare the third spectral data with a plurality of second spectral data to determine whether or not the plurality of second spectral data includes second spectral data similar to the third spectral data, and detect the third optical signal based on the determination result.

[0051] This allows the presence or absence of second spectral data similar to the third spectral data to be used to detect the third optical signal, thereby enabling more useful detection of the third optical signal.

[0052] Furthermore, the detection device 13 according to this embodiment is a detection device 13 that detects an optical signal and outputs a detection result, and includes an analysis unit 131 that generates a plurality of second spectral data having fewer frequency components than the plurality of first spectral data by performing sparse principal component analysis on a plurality of first spectral data obtained from a plurality of second optical signals that are nonlinearly converted from a predetermined plurality of first optical signals that differ in at least one of time waveform, intensity, amplitude, and phase, and a detection unit 132 that compares third spectral data obtained from a fourth optical signal that is nonlinearly converted from a third optical signal with the plurality of second spectral data and detects the third optical signal based on the comparison result.

[0053] This makes it possible to achieve the same effects as the optical signal detection system 10 described above.

[0054] Moreover, the optical signal detection method according to the present embodiment includes nonlinearly converting a predetermined plurality of first optical signals, which differ in at least one of time waveform, intensity, amplitude, and phase, into a plurality of second optical signals (S100), acquiring a plurality of first spectral data from each of the second optical signals (S101), performing sparse principal component analysis on the plurality of first spectral data to generate a plurality of second spectral data having fewer frequency components than the plurality of first spectral data (S102), nonlinearly converting a third optical signal into a fourth optical signal (S110), acquiring third spectral data from the fourth optical signal (S111), comparing the third spectral data with the plurality of second spectral data (S112), detecting the third optical signal based on a result of the comparison (S113), and outputting a detection result (S114).

[0055] This makes it possible to achieve the same effects as the optical signal detection system 10 described above.

[0056] As described above, the number of frequency components required for the spectral data differs between the detection phase and the analysis phase. That is, the number of frequency components required for the first spectral data is greater than the number of frequency components required for the third spectral data. Therefore, different spectrometers 12 may be used in the detection phase and the analysis phase.

[0057] Example 1 Next, a first embodiment will be described. In this embodiment, the optical signal detection system 10 according to the above embodiment is applied to a waveform reconstruction technique. The processing of the optical signal detection system 10 in this embodiment will be described below.

[0058] [2.1 Analysis Phase] The nonlinear converter 11 nonlinearly converts a predetermined plurality of first optical signals into a plurality of second optical signals. In this embodiment, optical pulse signals having different time waveforms are used as the predetermined plurality of first optical signals. Each of the plurality of second optical signals has a spectrum that depends on the time waveform of the corresponding first optical signal. Preferably, the plurality of second optical signals have spectra that are different from one another.

[0059] The spectrometer 12 acquires a plurality of first spectral data from a plurality of second optical signals. At this time, the plurality of first spectral data can represent differences in the time waveforms of the plurality of first optical signals.

[0060] The analysis unit 131 of the detection device 13 performs sparse principal component analysis on the plurality of first spectral data thus acquired, thereby generating and saving a plurality of second spectral data. As a result, the plurality of first spectral data is converted into a plurality of second spectral data. This spectral data conversion reduces the number of frequency components included in the spectral data. For example, the first spectral data consisting of 256 frequency components is converted into the second spectral data consisting of 9 frequency components.

[0061] [2.2 Detection Phase] The nonlinear converter 11 nonlinearly converts the third optical signal into a fourth optical signal. The third optical signal is an optical pulse signal having an unknown time waveform. The spectrometer 12 acquires third spectral data from the fourth optical signal. At this time, the third spectral data depends on the time waveform of the third optical signal. Furthermore, the number of frequency components included in the third spectral data matches the number of frequency components included in each of the plurality of second spectral data.

[0062] The detector 132 of the detecting device 13 compares the third spectral data thus acquired with a plurality of second spectral data to search for second spectral data similar to the third spectral data. Then, the detector 132 detects the time waveform of the first optical signal corresponding to the searched second spectral data as the time waveform of the third optical signal. This reconstructs the time waveform of the third optical signal.

[0063] [2.3 Effects, etc.] As described above, in the optical signal detection system 10 according to this embodiment, the multiple first optical signals have different time waveforms, and the detection unit 132 searches for second spectral data similar to the third spectral data by comparing the third spectral data with the multiple second spectral data, and detects the time waveform of the first optical signal corresponding to the searched second spectral data as the time waveform of the third optical signal.

[0064] This allows the optical signal detection system 10 to be applied to waveform reconstruction technology for optical pulse signals. In this case, the time waveform of an optical pulse signal can be reconstructed with a relatively simple configuration without using an ultrafast time gate or a reference light source. In addition, the effect of reducing frequency components by sparse principal component analysis allows for faster waveform reconstruction.

[0065] Example 2 Next, a second embodiment will be described. In this embodiment, the optical signal detection system 10 according to the above embodiment is applied to optical technology for analog-to-digital conversion. The processing of the optical signal detection system 10 in this embodiment will be described below.

[0066] [3.1 Analysis Phase] The nonlinear converter 11 nonlinearly converts a predetermined plurality of first optical signals into a plurality of second optical signals. In this embodiment, the predetermined plurality of first optical signals are optical pulse signals each having a plurality of different intensities assigned to different digital data. Such first optical signals can represent a plurality of digital data by their intensities. For example, a first optical signal having a first intensity represents first digital data, and a first optical signal having a second intensity different from the first intensity represents second digital data different from the first digital data. Each of the plurality of second optical signals has a spectrum that depends on the intensity of the corresponding first optical signal. Preferably, the plurality of second optical signals have spectra different from each other.

[0067] The spectrometer 12 acquires a plurality of first spectral data from a plurality of second optical signals, where the plurality of first spectral data can represent differences in intensity among the plurality of first optical signals.

[0068] The analysis unit 131 of the detection device 13 performs sparse principal component analysis on the plurality of first spectral data thus acquired, thereby generating and storing a plurality of second spectral data. As a result, the plurality of first spectral data is converted into a plurality of second spectral data. This conversion of the spectral data reduces the frequency components contained in the spectral data.

[0069] [3.2 Detection Phase] The nonlinear converter 11 nonlinearly converts the third optical signal into a fourth optical signal. The third optical signal is an optical pulse signal having unknown intensity. The spectrometer 12 acquires third spectral data from the fourth optical signal. At this time, the third spectral data depends on the time waveform of the third optical signal. Furthermore, the number of frequency components included in the third spectral data matches the number of frequency components included in each of the plurality of second spectral data.

[0070] The detector 132 of the detector 13 compares the third spectral data thus acquired with a plurality of second spectral data to search for second spectral data similar to the third spectral data. The detector 132 then detects the intensity of the first optical signal corresponding to the searched second spectral data as the intensity of the third optical signal. This makes it possible to detect the digital data represented by the third optical signal.

[0071] Here, an example of application of the optical signal detection system 10 according to this embodiment to analog / digital conversion will be described in comparison with an analog / digital conversion system according to the prior art. FIG. 5 is a diagram showing an optical analog / digital conversion system according to the prior art. FIG. 6 is a diagram showing an example of application of the optical signal detection system 10 according to the embodiment to analog / digital conversion. FIGS. 5 and 6 show an example of detecting a plurality of third optical signals having a plurality of different intensities (unknown) assigned to a plurality of different digital data, respectively.

[0072] In the prior art of FIG. 5, the third optical signal is N1 The step-by-step intensity change represents N1-bit digital data, where N1 is a natural number. In FIG. 5, the plurality of third optical signals are converted by an intensity-wavelength converter into optical signals having wavelengths corresponding to the intensities, and the spectrum is compressed by a spectral compressor. The presence or absence of frequency components at M1 frequencies from the optical signals that have undergone intensity-wavelength conversion and spectral compression in this manner can be detected using, for example, M1 A / D converters with 2-bit resolution, thereby obtaining digital data corresponding to the intensities of the third optical signals. In this case, M1 is a 2-bit number. N1 This results in an N1-bit analog-to-digital conversion.

[0073] In the application example of Figure 6, the third optical signal is N2The intensity change of the stage represents N2-bit digital data. Here, N2 is a natural number greater than N1. In FIG. 6, a plurality of third optical signals are nonlinearly converted into fourth optical signals in sequence by the nonlinear converter 11. Then, the optical splitter 12 uses M2 A / D converters to obtain third spectral data consisting of M2 frequency components from each fourth optical signal. At this time, M2 is a natural number smaller than M1 and 2 N2 . Each of the M2 A / D converters measures the value (power value) of the corresponding frequency component with a resolution of L2 bits lower than N2 bits. That is, the optical splitter 12 obtains the value of each frequency component with a resolution lower than the resolution of the intensities of the plurality of first optical signals. Each of the third spectral data thus obtained is compared with a plurality of second spectral data stored in advance in the detection device 13, and the intensity of each third optical signal is detected based on the comparison result.

[0074] As described above, in FIG. 6, analog / digital conversion can be realized with a number (M2 < M1) of A / D converters less than the resolution of the intensity change of the third optical signal. Furthermore, by using the nonlinear converter 11, analog / digital conversion can be realized with a higher resolution (N2 > N1) than the prior art using an intensity wavelength converter and a spectral compressor.

[0075] [3.3 Effects, etc.] As described above, in the optical signal detection system 10 according to the present embodiment, the plurality of first optical signals each have different intensities respectively assigned to different digital data, and the detection unit 132 compares the third spectral data with the plurality of second spectral data to search for second spectral data similar to the third spectral data, and detects the intensity of the first optical signal corresponding to the searched second spectral data as the intensity of the third optical signal.

[0076] This allows the optical signal detection system 10 to be applied to optical analog-to-digital conversion technology. This eliminates the need for intensity-to-wavelength conversion and spectral compression, enabling higher-resolution analog-to-digital conversion. Furthermore, the frequency component reduction effect achieved by sparse principal component analysis allows for faster analog-to-digital conversion.

[0077] Furthermore, for example, in the optical signal detection system 10 according to this embodiment, the spectrometer 12 may acquire the value of each frequency component at a resolution lower than the resolution of the intensities of the plurality of first optical signals.

[0078] This allows a change in the intensity of an optical signal with higher resolution to be captured as a change in frequency components with lower resolution, thereby achieving high-precision signal detection using low-precision hardware.

[0079] Example 3 Next, a third embodiment will be described. In this embodiment, the optical signal detection system 10 according to the above embodiment is applied to digital coherent receiving technology. The processing of the optical signal detection system 10 in this embodiment will be described below.

[0080] [4.1 Analysis Phase] The nonlinear converter 11 nonlinearly converts a plurality of predetermined first optical signals into a plurality of second optical signals. In this embodiment, the predetermined plurality of first optical signals are optical signals modulated with a plurality of different combinations of amplitudes and phases, each assigned to a different digital data. Examples of modulation methods that can be used include, but are not limited to, QAM (Quadrature Amplitude Modulation). Such first optical signals can represent a plurality of digital data by combinations of amplitudes and phases. For example, a first optical signal having a first amplitude and a first phase represents first digital data, and a first optical signal having a second amplitude and a first phase different from the first amplitude represents second digital data different from the first digital data. Furthermore, each of the plurality of second optical signals has a spectrum that depends on the combination of amplitude and phase of the corresponding first optical signal. Preferably, the plurality of second optical signals have spectra different from each other.

[0081] The spectrometer 12 acquires a plurality of first spectral data from a plurality of second optical signals, where the plurality of first spectral data can represent differences in combinations of amplitude and phase in the plurality of first optical signals.

[0082] The analysis unit 131 of the detection device 13 performs sparse principal component analysis on the plurality of first spectral data thus acquired, thereby generating and storing a plurality of second spectral data. As a result, the plurality of first spectral data is converted into a plurality of second spectral data. This conversion of the spectral data reduces the frequency components contained in the spectral data.

[0083] [4.2 Detection Phase] The nonlinear converter 11 nonlinearly converts the third optical signal into a fourth optical signal. The third optical signal is an optical signal having an unknown combination of amplitude and phase. The spectrometer 12 acquires third spectral data from the fourth optical signal. At this time, the third spectral data depends on the combination of amplitude and phase of the third optical signal. Furthermore, the number of frequency components included in the third spectral data matches the number of frequency components included in each of the plurality of second spectral data.

[0084] The detector 132 of the detector 13 compares the third spectral data thus acquired with a plurality of second spectral data to search for second spectral data similar to the third spectral data. The detector 132 then detects the combination of amplitude and phase of the first optical signal corresponding to the searched second spectral data as the combination of amplitude and phase of the third optical signal. This makes it possible to detect the digital data represented by the third optical signal.

[0085] [4.3 Effects, etc.] As described above, in the optical signal detection system 10 according to this embodiment, the multiple first optical signals are signals modulated with multiple combinations of amplitudes and phases, each assigned to a different digital data, and the detection unit 132 may search for second spectral data similar to the third spectral data by comparing the third spectral data with the multiple second spectral data, and detect the combination of amplitudes and phases of the first optical signal corresponding to the searched second spectral data as the combination of amplitudes and phases of the third optical signal.

[0086] This allows the optical signal detection system 10 to be applied to digital coherent receiving technology. By using nonlinear conversion, the number of amplitude and phase combinations can be increased, enabling faster digital data transmission. For example, when QAM is used as the modulation method, higher-order QAM can be used. Furthermore, it is possible to omit processes such as detecting I and Q components by interfering between an optical signal and laser light. Furthermore, the reduction of frequency components achieved by sparse principal component analysis allows faster demodulation.

[0087] Example 4 Next, a fourth embodiment will be described. In this embodiment, the optical signal detection system 10 according to the above embodiment is applied to the detection of an abnormal state. The processing of the optical signal detection system 10 in this embodiment will be described below.

[0088] [5.1 Analysis Phase] The nonlinear converter 11 nonlinearly converts a predetermined plurality of first optical signals into a plurality of second optical signals. In this embodiment, optical signals indicating a normal state are used as the predetermined plurality of first optical signals. For example, optical signals that depend on the state of an object (e.g., a light source, infrastructure equipment, etc.) and are output when the object is normal are used as the predetermined plurality of first optical signals. In this case, the predetermined plurality of first optical signals does not include an optical signal that is output when the object is abnormal.

[0089] The spectrometer 12 acquires a plurality of first spectral data from a plurality of second optical signals, where the plurality of first spectral data can represent differences between the plurality of first optical signals.

[0090] The analysis unit 131 of the detection device 13 performs sparse principal component analysis on the plurality of first spectral data thus acquired, thereby generating and storing a plurality of second spectral data. As a result, the plurality of first spectral data is converted into a plurality of second spectral data. This conversion of the spectral data reduces the frequency components contained in the spectral data.

[0091] [5.2 Detection Phase] The nonlinear converter 11 nonlinearly converts the third optical signal into a fourth optical signal. The third optical signal is an optical signal that indicates an unknown state. The spectrometer 12 then acquires third spectral data from the fourth optical signal. At this time, the third spectral data depends on the third optical signal. Furthermore, the number of frequency components included in the third spectral data matches the number of frequency components included in each of the plurality of second spectral data.

[0092] The detector 132 of the detecting device 13 compares the third spectral data thus acquired with the plurality of second spectral data to determine whether the plurality of second spectral data includes second spectral data similar to the third spectral data. If the detector 132 determines that there is no second spectral data similar to the third spectral data, it detects the third optical signal as an optical signal indicating an abnormal state. On the other hand, if the detector 132 determines that there is second spectral data similar to the third spectral data, it detects the third optical signal as an optical signal indicating a normal state.

[0093] [5.3 Effects, etc.] As described above, in the optical signal detection system 10 according to this embodiment, each of the plurality of first optical signals represents an optical signal indicating a normal state, and the detection unit 132 compares the third spectral data with the plurality of second spectral data to determine whether or not the plurality of second spectral data includes second spectral data similar to the third spectral data, and if it is determined that there is no second spectral data similar to the third spectral data, detects the third optical signal as an optical signal indicating an abnormal state.

[0094] This allows the optical signal detection system 10 to be applied to technology for detecting abnormal conditions. In this case, the use of nonlinear transformation can reduce false detections of abnormal conditions. Furthermore, the effect of reducing frequency components through sparse principal component analysis can also achieve lower load and / or faster detection.

[0095] (Other embodiments) While the optical signal detection system according to one or more aspects of the present invention has been described above based on embodiments and examples, the present invention is not limited to these embodiments. As long as they do not deviate from the spirit of the present invention, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of one or more aspects of the present invention.

[0096] For example, in the above embodiment, the detecting device 13 executes the analysis phase, but this is not limiting. For example, the analysis phase may be executed by a device other than the detecting device 13. In this case, the detecting device 13 may acquire information associating multiple second spectral data with the characteristics of the first optical signal from the other device and store the information in storage. In this case, the detecting device 13 may not include the analyzing unit 131. [Industrial Applicability]

[0097] The present invention can be used in optical signal waveform reconstruction technology, analog-to-digital conversion optical technology, digital coherent receiving technology, and the like. [Explanation of symbols]

[0098] 10 Optical signal detection system 11 Nonlinear Transformers 12 Spectrometer 13 Detection equipment 131 Analysis Department 132 Detector

Claims

1. a nonlinear converter that nonlinearly converts a plurality of predetermined first optical signals, each of which differs in at least one of time waveform, intensity, amplitude, and phase, into a plurality of second optical signals, and further nonlinearly converts a third optical signal into a fourth optical signal; a spectrometer that acquires a plurality of first spectral data from the plurality of second optical signals, respectively, and further acquires a third spectral data from the fourth optical signal; a detection device that detects the third optical signal and outputs a detection result, The detection device includes: an analysis unit that performs sparse principal component analysis on the plurality of first spectral data to generate a plurality of second spectral data having fewer frequency components than the plurality of first spectral data; a detector that compares the third spectral data with the plurality of second spectral data and detects the third optical signal based on a result of the comparison. Optical signal detection system.

2. The detection unit searching for second spectral data similar to the third spectral data by comparing the third spectral data with the plurality of second spectral data; detecting the third optical signal based on the first optical signal corresponding to the searched second spectral data; The optical signal detection system of claim 1 .

3. the plurality of first optical signals have different time waveforms; the detector detects the time waveform of the first optical signal corresponding to the searched second spectrum data as the time waveform of the third optical signal; The optical signal detection system of claim 2 .

4. the plurality of first optical signals have a plurality of different intensities respectively assigned to different digital data; the detector detects the intensity of the first optical signal corresponding to the searched second spectrum data as the intensity of the third optical signal; The optical signal detection system of claim 2 .

5. the spectrometer acquires intensity values ​​of the respective frequency components at a resolution lower than the resolution of the intensities of the plurality of first optical signals; The optical signal detection system of claim 4 .

6. the plurality of first optical signals are signals modulated with a plurality of combinations of amplitudes and phases respectively assigned to different digital data, the detector detects a combination of the amplitude and phase of the first optical signal corresponding to the searched second spectrum data as a combination of the amplitude and phase of the third optical signal; The optical signal detection system of claim 2 .

7. The detection unit comparing the third spectral data with the plurality of second spectral data to determine whether or not the plurality of second spectral data includes second spectral data similar to the third spectral data; detecting the third optical signal based on the result of the determination; The optical signal detection system of claim 1 .

8. each of the plurality of first optical signals represents an optical signal indicating a normal state; The detection unit detecting the third optical signal as an optical signal indicating an abnormal state when it is determined that there is no second spectral data similar to the third spectral data; The optical signal detection system of claim 7 .

9. An optical signal detection device that detects an optical signal and outputs a detection result, an analysis unit that generates a plurality of second spectral data having fewer frequency components than the plurality of first spectral data by performing sparse principal component analysis on a plurality of first spectral data acquired from a plurality of second optical signals that are nonlinearly converted from a predetermined plurality of first optical signals that differ in at least one of time waveform, intensity, amplitude, and phase; a detection unit that compares third spectral data acquired from a fourth optical signal nonlinearly converted from the third optical signal with the plurality of second spectral data, and detects the third optical signal based on a result of the comparison. Optical signal detection device.

10. nonlinearly converting a plurality of predetermined first optical signals, each of which differs in at least one of time waveform, intensity, amplitude, and phase, into a plurality of second optical signals; acquiring a plurality of first spectral data from the plurality of second optical signals, generating a plurality of second spectral data sets having fewer frequency components than the plurality of first spectral data sets by performing sparse principal component analysis on the plurality of first spectral data sets; nonlinearly converting the third optical signal into a fourth optical signal; obtaining third spectral data from the fourth optical signal; comparing the third spectral data with the plurality of second spectral data; detecting the third optical signal based on a result of the comparison; Output the detection results, Optical signal detection method.

Images