JP3540687B2 - Optical signal processing circuit and method thereof - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical signal processing circuit and method for demodulating and modulating an ultra-high-speed optical signal, and more particularly to an optical signal processing circuit and method for multiplexing and demultiplexing a time-series optical code division multiplexed signal.
[0002]
[Prior art]
With the development of optical signal transmission and optical signal processing technologies, in order to secure lower cost and higher transmission capacity, as a multiplexing method that complements the time division multiplexing method and the wavelength division multiplexing method, a CDM (Code Division Multiple: It has become necessary to use a code division multiplexing scheme.
[0003]
In the CDM system, a signal to be multiplexed is encoded by converting it into coefficients of respective basis functions in an orthogonal function system or a quasi-orthogonal function system on a space axis, a time axis, or a frequency axis, and then multiplexed. This is a multiplexing method. By taking the inner product of the signal to be decoded and the basis function of the signal to be decoded, signal information as a coefficient can be extracted.
[0004]
FIG. 1 shows an example of a conventional encoding / decoding circuit for implementing a code division multiplexing method in the frequency domain. In FIG. 1, reference numeral 1 denotes an arrayed waveguide grating, and a waveguide 2, slab waveguides 3, 5 and an arrayed waveguide 4 are formed on a silicon substrate 6. Reference numeral 7 denotes a spatial phase filter arranged near the focal plane of the slab waveguide 5 of the arrayed waveguide grating 1.
[0005]
The width of each phase filter element in the spatial phase filter 7 is at most about the spatial resolution of the arrayed waveguide grating 1, and there is no distribution in the depth direction of the filter. In this case, the incident signal spectrum spatially developed on the focal plane of the slab waveguide 5 is given a phase change independently by the spatial phase filter 7, is simply reflected in the vertical direction, and is re-transmitted to the array waveguide 4. Will be combined.
[0006]
FIG. 2 shows an encoding / decoding process of a conventional code division multiplexing method in the frequency domain.
[0007]
Each of the time-series signals D1, D2, D3, and D4 shown in FIG. 1A is temporarily expanded into a frequency spectrum, and the phases of the spectral components are encoded according to a basis function, thereby obtaining a signal as shown in FIG. Are coded signals C1, C2, C3, and C4. The coded signals C1, C2, C3 and C4 are multiplexed and become a CDM multiplexed signal C1 + C2 + C3 + C4 as shown in FIG.
[0008]
As described above, the CDM multiplexed signal is demultiplexed by a star coupler or the like by the number of signals to be decoded as shown in FIG. By applying a phase filter having a frequency response function opposite to that used in (1), an original signal to be extracted can be obtained as shown in FIG.
[0009]
[Problems to be solved by the invention]
However, in the above-described circuit, an unnecessary signal other than a desired signal is superimposed as noise upon decoding. Therefore, threshold value processing is required to extract a complete original signal as shown in FIG. , And a high-speed threshold element is required. Although it is very difficult to easily fabricate a high-speed threshold element, no alternative method has been devised. It was a big challenge. Further, in this case, when extracting a desired signal component, other signal information is completely lost due to the characteristics of the threshold element, so that the loss at the time of demultiplexing becomes extremely large as the number of multiplexes increases. There was a problem that would.
[0010]
The present invention has been made in view of the above problems, and in a code division multiplexing system in the frequency domain, creates a code division multiplexed signal by collectively performing encoding and multiplexing from an original signal without using a threshold element, and It is another object of the present invention to provide an optical signal processing circuit and a method for extracting an original signal by collectively performing decoding and demultiplexing from a code division multiplexed signal.
[0011]
[Means for Solving the Problems]
To solve the above problems, the present invention, a plurality of first time to convert the plurality of time-series signal light respectively to the space signal light - space conversion means and said plurality of first time - from the space converting means output a plurality of spatial signal light is focused respectively, a first imaging means to interfere with each other, is disposed in the vicinity of the focal plane of the first imaging means, is incident on the first imaging means collectively encode a plurality of spatial signal light, and transmission type hologram that diffracts the same angular direction, a second imaging means for converting the diffracted light from the hologram to the spatial signal light, the second imaging second time to the converting spatial signal light from the unit in a time sequence code division multiplexed signal light - propose an optical signal processing circuit, characterized in that it comprises a spatial transformation unit.
[0012]
According to the configuration, the plurality of original signals incident on the plurality of first time-space conversion units are converted into spatial signal light, Fourier-transformed by the first imaging unit, and developed on a hologram. And spatially multiplexed at the same time, are converted into spatial signal light by the second imaging means, and are further converted into one time-series signal light by the second time-space converting means, that is, code division multiplexing. Converted to a signal.
[0013]
Further, in order to solve the above-mentioned problem, in the present invention, a first time-space conversion means for converting a time-series code division multiplexed signal light into a spatial signal light, and a signal output from the first time-space conversion means. A first imaging means for imaging the spatial signal light, and a spatial signal light which is arranged near the focal plane of the first imaging means and collectively decodes the spatial signal light incident on the first imaging means. A transmission type hologram for diffracting light in different angular directions, a second imaging means for converting a plurality of diffracted lights from the hologram diffracted in different angular directions into a plurality of spatial signal lights, and the second imaging means. An optical signal processing circuit comprising a plurality of second time-space converting means for converting a plurality of spatial signal lights from the image means into time-series signal lights, respectively, is proposed.
According to the configuration, the code division multiplexed signal incident on the first time-space conversion means is converted into spatial signal light, Fourier-transformed by the first imaging means, and developed on a hologram. Simultaneously with decoding, the signal is spatially demultiplexed, converted into spatial signal light by the second imaging means, and further converted into individual time-series signal light, that is, an original signal by the second time-space converting means. .
[0014]
At this time, the transmission hologram may be replaced with a reflection hologram, and the first imaging means and the second imaging means may be shared.
[0015]
Also, in these optical signal processing circuit, pre-Symbol first and second time - space converting means constituted by an array waveguide, said first and second imaging means for Fourier transform spatial signal light function It can be composed of a slab waveguide having a pre-Symbol first and second time - space converting means constituted by the diffraction grating, Fourier transforming the spatial signal light of the first and second imaging means It can also be constituted by a lens.
[0016]
Furthermore, in these optical signal processing circuits, the hologram is constituted by a phase hologram, or is constituted by an amplitude hologram, or is constituted by a photorefractive material, or is constituted by a spatial phase modulator array, or is constituted by a spatial intensity modulator. It can also be composed of an array.
[0017]
In order to solve the problems described above, in the present invention, the step of converting the time-based Retsufu No. division multiplexed signal light that has been encoded in spatial signal light, is imaged the spatial signal light, a Fourier transform image and obtaining said by hologram Fourier transform image, and obtaining a diffraction image that diffracts each optical signal component of the sign-division multiplexed signal light in different angular directions, the diffraction pattern of the respective Fourier transform, each space Converting the spatial signal light into a plurality of spatially separated time-series signal lights, and restoring the original signal before code division multiplexing. We propose a processing method.
[0018]
Further, in order to solve the above-described problem, in the present invention, a step of converting each of the plurality of time-series signal lights into a first spatial signal light; is focused on specific point, obtaining a Fourier transform image, the hologram the Fourier transform image is converted into each different that sign-split signal light of each of the optical signal components, diffracted in the same angular direction Obtaining a diffraction image, performing a Fourier transform on the diffraction image, and converting the diffraction image into a second spatial signal light, converting the second spatial signal light into a time-series signal light, and generating a code division multiplexed signal. An optical signal processing method is proposed.
[0019]
In these optical signal processing methods, the method of forming the image distribution of the hologram is an optical manufacturing method using actual signal light and reference light, or a numerical calculation using virtual signal light and reference light. Method.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 3 shows an example of an embodiment of an optical signal processing circuit according to the present invention, here an example of an optical code division multiplexing / optical code division demultiplexing circuit for realizing a code division multiplexing method in the frequency domain. In FIG. 3, reference numeral 10 denotes an arrayed waveguide grating, in which a waveguide 11, a first slab waveguide 12, an arrayed waveguide 13, and a second slab waveguide 14 are formed on a silicon substrate 15. Reference numeral 20 denotes a reflection type hologram substrate.
[0021]
The waveguide 11 is for allowing signal light to enter and exit. The first slab waveguide 12 has a function of distributing the light of the waveguide 11 to the array waveguide 13. The array waveguide 13 has a function of performing time-space conversion of the incident signal light.
[0022]
In the present embodiment, there are five sets of the waveguide 11, the slab waveguide 12, and the array waveguide 13, each of which is incident on the second slab waveguide 14. In the present embodiment, since the number of multiplexed CDMs is four, there are five sets of waveguides 11, slab waveguides 12, and arrayed waveguides 13. In general, when n signals are multiplexed / separated, Has (n + 1) pairs.
[0023]
The second slab waveguide 14 has a function of Fourier transforming each output light from the arrayed waveguide 13. In other words, on the end face (focal plane) of the slab waveguide 14 opposite to the end face connected to the arrayed waveguide 13, the frequency component of the input optical signal is spatially developed, and the spatial axis and the frequency axis are linear. They are proportional to each other through variance.
[0024]
In the present embodiment, the hologram substrate 20 is almost in close contact with the focal plane of the slab waveguide 14, but a lens can be further provided on the focal plane of the slab waveguide 14, in which case the coupling efficiency Improvement can be expected.
[0025]
The design center wavelength of the arrayed waveguide grating (optical circuit) 10 used in this embodiment is 1552 nm, the number of the five arrayed waveguides 13 is 378, and the diffraction order (the optical path length difference between adjacent waveguides is the wavelength). Are 53 in each case. The linear dispersion at the focal plane of the slab waveguide 14 is 1.25 GHz / μm, and the frequency resolution is about 12.7 GHz.
[0026]
The waveguide shown in FIG. 3 is deposited as a glass fine particle film in the order of a lower cladding layer and a core layer by a flame hydrolysis deposition method (FHD method) on a single crystal silicon substrate, and then heated to a high temperature in an annealing furnace. Then, a transparent glass film covering the silicon substrate is formed. Thereafter, patterning is performed in the shape of a waveguide, and unnecessary core layers are removed using dry etching. Then, an upper cladding layer is deposited again using the FHD method, and heated to a high temperature to make the upper cladding layer transparent. It can be manufactured by the following.
[0027]
Note that a semiconductor layer having a refractive index higher than that of a cladding layer such as InGaAsP is epitaxially grown as a core layer on a semiconductor layer such as InP, and a semiconductor waveguide structure manufactured by patterning and etching, a deuterated PMMA core, and an ultraviolet cladding layer. It is clear that a waveguide having a similar function can be produced by a waveguide structure made of a polymer which is used as a cured resin. In this case, it is desirable that the material be sufficiently transparent in the wavelength range to be used.
[0028]
FIG. 4 is a conceptual diagram when the CDM multiplexed signal is demultiplexed by the optical circuit of FIG. Of the array waveguides 13 in FIG. 4, the code division multiplexed signals C1, C2, C3, and C4, which are incident from one array waveguide 13 and are coded and multiplexed with different codes, respectively, are Fourier-transformed, and The spectrum is spatially spread on a hologram substrate 20 arranged near the focal plane of the slab waveguide 14.
[0029]
The Fourier transform hologram is multiplex-recorded on the hologram substrate 20, and the coded signals C1, C2, C3, and C4 are decoded into original signals D1, D2, D3, and D4, and reflected at different angles. It is configured.
[0030]
By preparing the array waveguides 13 in the respective reflection angle directions and making the array waveguides 13 enter the respective array waveguides 13, the CDM multiplexed signal can be spatially separated. As shown in FIG. 5, a plurality of signals can be collectively encoded and multiplexed by using the demultiplexing process in FIG. 4 in reverse.
[0031]
FIG. 6 shows an encoding / decoding process of the code division multiplexing method in the frequency domain of the present invention.
[0032]
The original signals D1, D2, D3, and D4 shown in FIG. 11A are coded and multiplexed at the same time, and become CDM multiplexed signals C1 + C2 + C3 + C4 as shown in FIGS. At the time of decoding and demultiplexing, the signal is spatially separated for each signal as shown in FIGS. 9D and 9E, and no other signal components are mixed. Such threshold processing is not required.
[0033]
FIG. 7 shows the configuration of the hologram substrate in FIGS. 7, a hologram medium 21 has a thickness of 10 μm in the present embodiment. The material is preferably a photorefractive material such as barium titanate or lithium niobate, but may be a photosensitive emulsion used for a film. Reference numeral 22 denotes a 0.3 μm-thick gold mirror, which was produced by vapor deposition using an electron beam vapor deposition method. Reference numeral 23 denotes a 1 mm thick quartz substrate for supporting the hologram medium 21 and the gold mirror 22.
[0034]
To write a Fourier transform hologram on the hologram substrate 20, first, a Fourier transform hologram is prepared on the hologram substrate 20 using the original signal D1 and the encoded signal C1 as shown in FIG. Then, as shown in FIGS. 8B, 8C and 8D, the array waveguide 13 into which the original signal is incident is changed, and the original signal D2 and the encoded signal C2, It can be manufactured by multiplex-recording four Fourier transform holograms of the original signal D3 and the encoded signal C3, and the original signal D4 and the encoded signal C4.
[0035]
In particular, when a photosensitive emulsion is used as the material of the hologram medium, an amplitude hologram can be obtained only by a development process, but can be made to function as a phase hologram by bleaching with a bleaching agent as a post-process. An improvement in diffraction efficiency can be expected as compared with a hologram.
[0036]
In the present embodiment, a hologram is manufactured by writing a Fourier transform hologram using an actual original signal and an encoded signal using a hologram medium. However, a hologram is manufactured using a computer generated hologram (CGH). You can also. FIG. 9 shows the configuration in that case. In FIG. 9, 31 is a gold mirror, 32 is a PMGI (polymethylglutarimide), and 33 is a quartz substrate.
[0037]
The hologram substrate of FIG. 9 is manufactured as follows. First, according to the method for producing a Fourier transform hologram shown in FIG. 8, hologram interference fringes are produced by numerical calculation using a computer. Numerical interference fringes obtained by calculation are obtained as intensity information. A hologram may be produced as it is as an intensity hologram, but it is desirable to change to a phase hologram because of the large loss in principle.
[0038]
Although various methods are already known as a method of converting an intensity hologram into a phase hologram, in the present embodiment, the Gerchberg-Saxton method (W. Gerchberg and WO Saxton, Optik, 35, 237, 1972). Phase hologram formation was used.
[0039]
The phased hologram was produced by changing the thickness of PMGI 32 spatially. In order to change the thickness of the PMGI 32 spatially, the PMGI 32 is applied on the quartz substrate 33 by spin coating, baked, and then the charge amount (dose amount) of the electron beam is changed using an electron beam lithography apparatus. Exposure is performed by etching the PMGI 32 to spatially change the etching speed according to the dose. Thereafter, 0.3 μm gold was deposited by an electron beam deposition apparatus to form a reflection mirror 31.
[0040]
In the present embodiment, a hologram medium is used as the hologram substrate. However, a similar effect can be obtained by using a spatial phase modulator array or a spatial intensity modulator array using a liquid crystal or a micromachine.
[0041]
Further, in the present embodiment, a reflection type hologram is used as shown in FIG. 3, but it is also possible to use a transmission type hologram.
[0042]
FIG. 10 shows another example of the embodiment of the optical signal processing circuit of the present invention, here an example of an optical code division multiplexing / optical code division separation circuit using a transmission type hologram. In FIG. 10, reference numeral 40a denotes a first arrayed waveguide grating, and a waveguide 41, a first slab waveguide 42, an arrayed waveguide 43, and a second slab waveguide 44 are formed on a silicon substrate 49. ing. Reference numeral 40b denotes a second arrayed waveguide grating, in which a waveguide 45, a first slab waveguide 46, an arrayed waveguide 47, and a second slab waveguide 48 are formed on a silicon substrate 49. . 50 is a transmission type hologram substrate.
[0043]
The decoding process using such a configuration is as follows. That is, the optical signal incident on the first arrayed waveguide grating 40a is diffracted by the transmission type hologram substrate 50 disposed near the focal plane of the slab waveguide 44 in the first arrayed waveguide grating 40a, and is diffracted by the second. Are distributed and output to a plurality of array waveguides 47 connected to the slab waveguide 48 in the array waveguide grating 40b. Therefore, the same effects as those of the embodiment shown in FIG. 3 can be obtained.
[0044]
Using these CDM encoding / multiplexing circuits and CDM decoding / separating circuits, 10 Gbit / s, RZ (Return-to-Zero) format 4-multiplexed CDM signals are collectively encoded and multiplexed and transmitted through an optical fiber. A circuit for batch decoding and demultiplexing was constructed, and transmission experiments were performed.
[0045]
FIG. 11 is a circuit configuration diagram showing an embodiment of a CDM multiplexed signal transmission system.
[0046]
In FIG. 11, reference numeral 61 denotes a 10 GHz repetition mode-locked light source, and reference numeral 62 denotes a LiNbO ₃ intensity modulator, which creates a pseudo random signal in RZ format. 63 is a CDM encoding / multiplexing circuit comprising the above-mentioned array waveguide grating and hologram substrate, 64 is an erbium-doped fiber amplifier (EDFA) for a booster, and 65 is an optical bandpass filter for cutting spontaneous emission light (ASE) of the EDFA64. is there. The above circuits 61 to 65 constitute an optical CDM transmitter. 66 is a dispersion shift fiber of 100 km.
[0047]
Also, 67 is a dispersion compensating fiber for compensating the dispersion of the transmission line, 68 is a front EDFA, 69 is an optical bandpass filter for cutting off spontaneous emission light (ASE) of the EDFA 68, 70 is the array waveguide grating and hologram substrate described above. A reference numeral 71 denotes an EDFA; 72, an optical band-pass filter for cutting off spontaneous emission light (ASE) of the EDFA 71; 73, a clock recovery device which is decoded and demultiplexed by a CDM decoding / separation circuit 70; The amplified signals were amplified by the EDFA 71, and the ASE was removed by the optical band-pass filter 72. Then, the signals were input to the clock reproducing device 73 to extract the clock and the signal. The above circuits 67 to 73 constitute an optical CDM receiver.
[0048]
Actually, using a mode-locked laser in the 1.55 μm optical communication wavelength band, a 10 Gbit / s, 4-channel CDM multiplexed signal is generated and transmitted over a 100 km dispersion-shifted fiber, and its bit error rate characteristics are measured. did. In addition, for comparison, a signal of one channel was also transmitted without encoding / decoding, and the characteristics were compared. When the hologram medium was used as the hologram, the CGH was used, The difference in reception sensitivity was 0.1 dB, which was within the measurement error range. In addition, the maximum input power at which error-free transmission was possible was a good value of +20 dB per channel when any hologram was used, compared to +5 dB obtained when encoding and decoding were not performed.
[0049]
In this embodiment, an arrayed waveguide grating is used to spatially expand the frequency components of the incident signal. However, as an equivalent configuration, a diffraction grating or a slab waveguide is used instead of the arrayed waveguides 13, 43, and 47. It goes without saying that a similar effect can be obtained even if a Fourier lens is used instead of 14, 44 and 48.
[0050]
【The invention's effect】
As described above, according to the present invention, by combining an arrayed waveguide grating and a Fourier transform hologram, an optical code division multiplexing / optical code division demultiplexing circuit that does not require a threshold element can be configured. Batch encoding / multiplexing and batch decoding / demultiplexing in a CDM system.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an example of a conventional frequency-domain code-division multiplexing encoding / decoding circuit. FIG. 2 is a conceptual diagram of a conventional frequency-domain code-division multiplexing encoding / decoding process. FIG. 3 is a configuration diagram showing an example of an embodiment of an optical signal processing circuit according to the present invention; FIG. 4 is a conceptual diagram showing how optical code division and separation are performed in the circuit in FIG. 3; FIG. FIG. 6 is a conceptual diagram showing the state of division multiplexing. FIG. 6 is a conceptual diagram of the encoding / decoding process of the code division multiplexing method in the frequency domain of the present invention. FIG. FIG. 9 is a view for explaining a method for producing a hologram on a hologram substrate according to the present invention. FIG. 9 is a structural view of a hologram substrate using a CGH according to the present invention. FIG. 10 shows another embodiment of the optical signal processing circuit according to the present invention. FIG. 11 is a diagram showing a configuration of a CDM according to the present invention. Configuration diagram showing an embodiment of a signal transmission system [EXPLANATION OF SYMBOLS]
10, 40a, 40b: arrayed waveguide grating, 11, 41, 45: waveguide, 12, 42, 46: first slab waveguide, 13, 43, 47: arrayed waveguide, 14, 44, 48: No. 2, slab waveguide, 15, 49: silicon substrate, 20: reflection hologram substrate, 21: hologram medium, 22, 31: gold mirror, 23, 33: quartz substrate, 32: PMGI, 50: transmission hologram substrate.

Claims (14)

A plurality of first time-space conversion means for converting a plurality of time-series signal lights into spatial signal lights, respectively ;
A first imaging unit that forms an image of each of the plurality of spatial signal lights output from the plurality of first time-space conversion units and causes interference with each other;
Said disposed in the vicinity of the focal plane of the first imaging means, the plurality of spatial signal light incident on the first imaging means collectively encoding, transmission type diffracting in the same angular direction the hologram,
Second imaging means for converting diffracted light from the hologram into spatial signal light;
Optical signal processing circuit, characterized in that it comprises a spatial transformation means - the second time that converts into a time series code division multiplexed signal light spatial signal light from the second imaging means. Time sequence code division multiplexed signal light first time that converts the spatial signal light - and space converting means,
Before SL first time - a first imaging means for imaging a spatial signal light output from the spatial transform unit,
Said disposed in the vicinity of the focal plane of the first imaging means, said first spatial signal light incident on the imaging means at once decoded, a transmission type hologram that diffracts into different angular directions,
A second imaging unit that converts a plurality of diffracted lights diffracted from the hologram into different spatial directions into a plurality of spatial signal lights,
An optical signal processing circuit comprising: a plurality of second time-space converting means for converting a plurality of spatial signal lights from the second imaging means into time-series signal lights, respectively . In the optical signal processing circuit according to claim 1 or 2, wherein the replacing the transmission hologram in the reflection-type hologram, light, characterized by being configured by shared a first imaging means and second imaging means Signal processing circuit. In the optical signal processing circuit according to any one of claims 1 to 3, before Symbol first and second time - space converting means constituted by an array waveguide, wherein the first and the spatial signal light and the second imaging means An optical signal processing circuit comprising a slab waveguide having a function of performing a Fourier transform on. In the optical signal processing circuit according to any one of claims 1 to 3, before Symbol first and second time - space converting means constituted by the diffraction grating, the spatial signal light of the first and second imaging means An optical signal processing circuit comprising a lens that performs Fourier transform. In the optical signal processing circuit according to any one of claims 1 to 5, the optical signal processing circuit, characterized in that the hologram constituted by a phase hologram. In the optical signal processing circuit according to any one of claims 1 to 5, the optical signal processing circuit, characterized in that the hologram constituted by an amplitude hologram. In the optical signal processing circuit according to any one of claims 1 to 5, the optical signal processing circuit, characterized in that it constitutes the hologram in a photorefractive material. In the optical signal processing circuit according to any one of claims 1 to 5, the optical signal processing circuit, characterized in that the hologram constituted by the spatial phase modulator array. In the optical signal processing circuit according to any one of claims 1 to 5, the optical signal processing circuit, characterized in that the hologram constituted by spatial intensity modulator array. A step of converting the time-based Retsufu No. division multiplexed signal light that has been encoded in the spatial signal light,
Imaging the spatial signal light to obtain a Fourier transform image;
By a hologram the Fourier transform image, and obtaining a diffraction image that diffracts each optical signal component of the sign-division multiplexed signal light in different angular directions,
A step of performing a Fourier transform on each of the diffraction images and converting each into a spatial signal light;
Converting the spatial signal lights into a plurality of spatially separated time-series signal lights and restoring the original signal before code division multiplexing. Converting each of the plurality of time-series signal lights into a first spatial signal light;
A step of causing each of the first spatial signal lights to enter from a different angle, forming an image at one spatial point, and obtaining a Fourier transform image;
By a hologram the Fourier transform image, and obtaining a diffraction image by converting each different that sign-split signal light of each of the optical signal components, diffracted in the same angular direction,
A step of performing a Fourier transform on the diffraction image to convert the diffraction image into a second spatial signal light;
Converting the second spatial signal light into a time-series signal light to generate a code division multiplexed signal. In the optical signal processing method according to claim 11 or 12, wherein the optical signal processing method being characterized in that the optical manufacturing method a method of forming an image distribution of the hologram by the actual signal light and reference light. In the optical signal processing method according to claim 11 or 12, wherein the optical signal processing method being characterized in that a numerically fabrication method according to the reference light and imaginary signal light forming method of an image distribution of the hologram.

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