Optical fiber-based processing system

Abstract

An optical processing unit for use as a base block of an optical processor system is presented. The optical processing unit is configured to implement a predetermined processing task on an input optical signal, and comprises: an input optical fiber unit for propagating the input optical signal and a weighted beam therethrough, an output optical fiber unit, and a non-linear all-optical modulator; and a non-linear all-optical modulator located upstream of the output fiber optic unit to be exposed to an interaction of the input optical signal and the weighted light beam, the non-linear all-optical modulator configured to apply spatial modulation of the weighted light beam to a light field of the input optical signal via the interaction, thus, a spatially modulated light field corresponding to the input light signal is generated, and the spatially modulated light field is allowed to propagate through an output fiber unit to a detection plane.

Description

Technical Field and Background

[0001] The present disclosure belongs to the field of optical fibers and relates to an optical fiber-based photonic processor, which is particularly suitable for optical data communications and optical computing devices, and can also be used for optically integrated artificial neural networks (ANNs).

[0002] In contrast to conventional electron-based computing, photonic computing uses the manipulation of light (photons) to perform computing processes. Generally speaking, the basic building block of modern electronic computers is the transistor. In photonic computers, the electronic components are replaced by optical components (equivalent optical transistors), i.e., photonic computer systems use light pulses instead of electronic transistors to form the basis of logic gates.

[0003] Conventional optical processing systems typically utilize hybrid electronic-optical processing, often referred to as optoelectronic processing. In these systems, optical signals are used for data transmission and certain processing operations, and can then be converted back into electronic signals for certain other processing operations. Such optoelectronic devices lose approximately 30% of their energy when converting electronic energy to photons and back. In addition, the conversion of optical signals to electrical signals and back slows down the transmission and processing of data. A large amount of research work is directed toward all-optical computing, which eliminates the need for optical-electrical-optical (OEO) conversion, thereby reducing the need for electrical energy and increasing processing rates.

[0004] Optical computing enables faster computational speeds than electronic systems because light pulses can be manipulated more quickly and allow for higher bandwidth transmission of information. General Description

[0005] There is a need in the art for novel approaches to using optical fibers to achieve various all-optical signal processing tasks, particularly for neural networks.

[0006] The present disclosure provides a novel fiber-based all-optical photonic processor that is configured and operable to perform various processing tasks achieved by optical manipulation involving linear effects and nonlinear effects (such as plasma dispersion effects). Some examples of computational tasks that can be performed by the photonic processor of the present disclosure include convolution, matrix multiplication, spatial filtering of light fields, etc.

[0007] The photonic processor of the present disclosure includes a certain number N (N≥1) of basic blocks, each of which is configured as a processing unit. The processing unit includes functional components such as a multimode fiber arrangement, which defines an input fiber unit and an output fiber unit (relative to the general light propagation direction through the processing unit) and a nonlinear optical modulator. The nonlinear optical modulator is located upstream of the output fiber unit, and can be located outside the input fiber unit (for example, one of the input fibers) downstream of the input fiber unit and / or can be integrated into the input fiber unit.

[0008] Nonlinear optical modulators can be configured using any known suitable technology to achieve nonlinear all-optical effects, such as light absorption, electro-optic effect (based on the Kerr effect induced by the interaction of two light fields), photorefractive effect (refractive index change in a material due to optically induced redistribution of electrons and holes), etc. Optical modulators can be configured as thin semiconductor elements, such as Si or Ge core optical fibers, or can be doped in the glass of optical fibers.

[0009] The input fiber unit is configured and operable to propagate the input optical signal and the weighted optical beam to achieve interaction of the input optical signal and the weighted optical beam with the nonlinear optical modulator. In some embodiments, this interaction occurs at the output end of the input fiber unit where the optical modulator is located, and in some other embodiments, this interaction occurs during propagation of the optical signal and the weighted optical beam along the same input optical fiber (which contains the optical modulator integral to the optical fiber), or a combination of these two implementations. The last is a so-called "hybrid" configuration, in which the nonlinear medium is integrated in the optical fiber in one axis and is an external material in the second axis.

[0010] It should be understood that the optical signal and the weighted light beam differ from each other in at least one optical property to avoid interference between them. In some embodiments, this can be achieved by using a weighted light beam having a wavelength different from the wavelength of the optical signal. In this case, the interaction between them is generated by optical nonlinearity. For example, the nonlinear optical modulator can be configured to perform plasma dispersion effects, light refraction effects, etc. In some other embodiments, the weighted light beam can have a wavelength substantially the same as the optical signal. In this case, the nonlinear optical modulator can be configured to perform cross-phase modulation effects, soliton effects, Kerr effects, etc.

[0011] The optical properties (wavelength and intensity) of the weighted light beam are selected so that the weighted light beam excites the optical modulator to induce a nonlinear all-optical effect (a change in the optical properties of the modulator) that appropriately modulates an input light beam that interacts with (e.g., passes through) the optical modulator. More specifically, in some non-limiting examples, the weighted light beam generates charge carriers (electron-hole pairs) when interacting with the optical modulator and is efficiently absorbed. The charge carriers so generated affect a corresponding modulation of the input light signal that interacts with the optical modulator, thereby allowing the modulated light signal to be transmitted through the optical modulator.

[0012] Hence, the processing task, which is a predetermined function applied to the input optical signal, involves an optical modulation effect exerted by the weighted optical beam on the input optical signal via interaction of the input optical signal and the weighted optical beam with the optical modulator.

[0013] The various functions involved in a specific processing task (e.g. Fourier and / or imaging) utilize the input optical signal and the weighted optical beam in the same or different domains (frequency domain and / or spatial domain). In general, the input optical signal and the weighted optical beam may propagate through the same or different optical fibers of the input optical fiber unit. In fact, this is possible regardless of whether the input optical signal and the weighted optical beam are to leave the input optical fiber unit in the same domain or in different domains. The input optical signal and the weighted optical beam have different optical properties (e.g. wavelength, polarization, phase, etc.).

[0014] The input optical signal and the weighted optical beam can be configured so that their primary Fourier planes are located at different positions. The length of the input optical fiber (and its refractive index profile) can be determined so that at the exit of the input optical fiber, one of the input signal and the weighted optical beam is Fourier transformed, while the other is not Fourier transformed, or both are Fourier transformed (although they have undergone different numbers of Fourier transformations during propagation through the input optical fiber unit).

[0015] As will be further described below, in the case where the input optical signal and the weighted optical beam have the same domain, the interaction of the two with the optical modulator results in the multiplication of the input optical signal with the weighted optical beam; and in the case where the input optical signal arrives at the interaction region in the frequency domain, its interaction with the optical modulator excited / spatial modulated by the weighted optical beam results in frequency filtering of the input optical signal. To this end, the input fiber unit as well as the output fiber unit are configured according to the predetermined function / processing task to be applied.

[0016] In some embodiments, the input fiber unit comprises at least one graded refractive index (GRIN) light guiding unit, which may be a GRIN fiber or rod or a planar waveguide. The construction and operation of such GRIN light guiding units are known per se and therefore do not require a detailed description, but it should be noted that, due to the fact that the refractive index in such a light guiding unit decreases from its periphery to the central region, the light passing through the GRIN light guiding unit undergoes a continuous refocusing (i.e. a lens effect).

[0017] In the following description, such GRIN light guiding units are referred to as GRIN fibers, but it should be noted that this term should be interpreted broadly, also covering GRIN rods and planar waveguides.

[0018] The length and temperature of the input fiber unit using GRIN fibers and the length and temperature of the output fiber unit are also chosen depending on the optical processing to be performed, ie depending on whether the plane in which the light leaves the fiber unit is a Fourier plane or not.

[0019] For example, in some embodiments, the predetermined task / function is a convolution of the input optical signal. In this case, the input optical fiber unit may be configured to implement the input optical signal and weighted beam The Fourier transform of both allows the input optical signal to be modulated by the weighted optical beam through the interaction of the input optical signal and the weighted optical beam with the optical modulator, thereby generating (where x denotes signal and w denotes weight). The output fiber unit is configured to implement an inverse Fourier transform of the modulated input optical signal when directing it to the detection plane, thereby giving overall operation.

[0020] As will be described below, in some embodiments, the input optical signal and the weighted optical beam may propagate through different optical fibers of the input optical fiber unit, in which case the optical modulator is located at the output ends of these optical fibers. In such embodiments, the two optical fibers of the input optical fiber unit may be configured to perform a Fourier transform of the corresponding optical field; or both optical fibers may be configured as imaging fibers; or one of the optical fibers may be configured to perform a Fourier transform of the input optical signal, while the other optical fiber through which the weighted optical beam propagates is an imaging fiber.

[0021] In some other embodiments, the input optical signal and the weighted optical beam propagate through the same optical fiber of the input optical fiber unit. In this case, in some embodiments, the optical modulator can be located at the output end of the optical fiber. The optical fiber through which the input optical signal and the weighted optical beam propagate can be configured to perform Fourier transform on both the input optical signal and the weighted optical beam, or can be configured as an imaging fiber for both, or can be configured to perform Fourier transform on one and perform imaging on the other. This depends on the wavelength of the optical beam and the length of the optical fiber.

[0022] In some other examples, in such a configuration that a common input optical fiber propagates both the input optical signal and the weighted optical beam, the optical modulator may be integrated within the optical fiber extending along it. This may be achieved by configuring the optical modulator to be a material constituting the core through which the two signals propagate, or by doping the glass of the input optical fiber with such nonlinear optical material. Such a configuration provides that the input optical signal and the weighted optical beam undergo multiple interactions with the optical modulator during their propagation along the optical fiber, resulting in a matrix multiplication at the output end of the input optical fiber unit. In some examples, such an input optical fiber may be configured to perform a Fourier transform on the light passing therethrough, in which case the output optical fiber unit is configured to perform an inverse Fourier transform, thereby providing a convolution of the input optical signal with the weighting function.

[0023] Therefore, according to a broad aspect of the present disclosure, there is provided an optical processor system, which includes at least one optical processing unit, which is configured to implement a predetermined processing task on an input optical signal and includes an optical fiber device, which defines: an input optical fiber unit, an output optical fiber unit and a nonlinear all-optical modulator, the input optical fiber unit is configured to propagate the input optical signal and a weighted optical beam toward an output plane positioned according to the predetermined function to be implemented, the weighted optical beam having at least one optical characteristic different from at least one optical characteristic of the input optical signal; the output optical fiber unit is spaced apart from the input optical fiber unit along a general light propagation direction through the optical processing unit and is configured to propagate light to a detection plane; the nonlinear all-optical modulator is located upstream of the output optical fiber unit, wherein the nonlinear all-optical modulator is exposed to interaction with a light field corresponding to the input optical signal and a light field corresponding to the weighted optical beam, and is switchable to a spatial modulation state by interaction with the light field corresponding to the weighted optical beam, so as to apply spatial modulation of the weighted optical beam to the light field corresponding to the input optical signal, thereby generating a spatially modulated light field corresponding to the input optical signal, and allowing the spatially modulated light field to propagate to the detection plane through the output optical fiber unit.

[0024] In some embodiments, the nonlinear all-optical modulator of the optical processing unit is housed in an output plane and is exposed to interaction with a light field corresponding to an input optical signal and a light field corresponding to a weighted optical beam, thereby applying the spatial modulation of the weighted optical beam to the light field corresponding to the input optical signal and generating a spatially modulated light field corresponding to the input optical signal.

[0025] The input fiber unit of the optical processing unit may include a common input fiber configured to propagate both the input optical signal and the weighted optical beam, or alternatively, the input fiber unit of the optical processing unit may include a first input fiber and a second input fiber configured to propagate the input optical signal and the weighted optical beam, respectively.

[0026] In some embodiments, when the input fiber unit of the optical processing unit includes a common input fiber configured to propagate both an input optical signal and a weighted optical beam, the nonlinear all-optical modulator includes a nonlinear medium integrated with the common input fiber, so that spatial modulation of the weighted optical beam is applied to the optical field corresponding to the input optical signal during the propagation of the input optical signal and the weighted optical beam through the common input optical fiber, thereby generating a spatially modulated optical field corresponding to the input optical signal.

[0027] In some embodiments, a nonlinear all-optical modulator has a first nonlinear medium integral to an input fiber and a second nonlinear medium at an output end of the input fiber.

[0028] In some embodiments, the optical processing unit has the following configuration: the input fiber unit includes at least one graded-index (GRIN) fiber, the at least one graded-index (GRIN) fiber is configured to apply a Fourier transform function to at least one of an input optical signal and a weighted optical beam, and the output plane is a Fourier plane relative to the optical input of the input fiber unit for the wavelength of at least one of the input optical signal and the weighted optical beam. The output fiber unit includes a GRIN fiber, the GRIN fiber is configured to apply a successive Fourier transform function to a spatially modulated optical field passing through the GRIN fiber, and the detection plane is a Fourier plane relative to the optical input of the GRIN fiber of the output fiber unit for the spatially modulated optical field (i.e., for the wavelength of the input optical signal).

[0029] In some examples, the input optical signal and the weighted optical beam propagate through a first GRIN fiber and a second GRIN fiber of the input optical fiber unit, the first GRIN fiber and the second GRIN fiber being configured to apply a Fourier transform to the input optical signal and the weighted optical beam, respectively. In this case, the nonlinear all-optical modulator of the optical processing unit is housed in the output plane and is exposed to interaction with the optical field corresponding to the input optical signal and the optical field corresponding to the weighted optical beam.

[0030] In some other examples, the input optical signal and the weighted optical beam propagate through the same GRIN fiber, which is configured to apply a Fourier transform to both the input optical signal and the weighted optical beam, or is configured to apply a Fourier transform to only the input optical signal. In such a case, a nonlinear all-optical modulator can be housed in the output plane, or the nonlinear all-optical modulator can be integrated with the GRIN fiber (e.g., the core of the GRIN fiber can be configured as a nonlinear all-optical modulator), thereby applying spatial modulation of the weighted optical beam to the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN fiber.

[0031] In some embodiments, the predetermined processing task implemented by the processing unit is the convolution between the input optical signal and the weighted optical beam, which convolution results from the interaction between the Fourier transform of the input optical signal and the weighted optical beam and the spatially modulated light field generated by the nonlinear all-optical modulator, and the continuous Fourier transform of the spatially modulated light field corresponding to the input optical signal.

[0032] In these embodiments, the input optical signal and the weighted optical beam may be propagated through respective first and second GRIN fibers of the input optical fiber unit, the first and second GRIN fibers being configured to apply a Fourier transform to the input optical signal and the weighted optical beam, and thus the nonlinear all-optical modulator is accommodated in the output plane of the input optical fiber unit. Alternatively, the input optical signal and the weighted optical beam may be propagated through the same GRIN fiber, which is configured to apply a Fourier transform to both the input optical signal and the weighted optical beam, in which case the nonlinear all-optical modulator is either a separate element accommodated in the output plane of the input optical fiber unit, or is integrated with the GRIN fiber, so as to apply spatial modulation of the weighted optical beam to the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN fibers.

[0033] In some embodiments, the predetermined processing task implemented by the processing unit is filtering selected spatial frequencies of the input optical signal, which filtering results from the interaction of the Fourier transform of the input optical signal and the weighted optical beam with the nonlinear all-optical modulator, and the continuous Fourier transform of the spatially modulated light field corresponding to the input optical signal.

[0034] In some examples of these embodiments, the input optical signal and the weighted optical beam may be propagated through a first optical fiber and a second optical fiber, respectively, wherein at least the first optical fiber is a GRIN fiber configured to implement a Fourier transform of the input optical signal, and the second optical fiber is configured as an imaging fiber for the weighted optical beam. In this case, the nonlinear all-optical modulator is a separate element housed in the output plane. In some other examples, the input optical signal and the weighted optical beam are propagated through the same GRIN fiber of the input optical fiber unit, which is configured to apply a Fourier transform to the input optical signal and is configured as an imaging fiber relative to the weighted optical beam. In this case, the nonlinear all-optical modulator may be a separate element located in the output plane, or may be integrated with the GRIN fiber (i.e., may be composed of a suitably configured GRIN fiber) to apply spatial modulation of the weighted optical beam to the Fourier transform of the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN fiber.

[0035] In some further embodiments, the predetermined processing task implemented by the processing unit may be a signal multiplication between an input optical signal and a weighted optical beam, the signal multiplication resulting from the interaction of the optical field corresponding to the input optical signal and the optical field corresponding to the weighted optical beam with the nonlinear all-optical modulator, and successive imaging of the spatially modulated optical field corresponding to the input optical signal on a detection plane. In such an embodiment, the input optical fiber unit may be configured such that the output plane is an image plane for the optical input of the input optical fiber unit relative to both the input optical signal and the weighted optical beam, and the output optical fiber unit is configured such that the detection plane is an imaging plane for the optical input of the output optical fiber unit relative to the input optical signal.

[0036] According to another broad aspect of the present invention, there is provided an optical processing unit configured to implement a predetermined processing task on an input optical signal, the optical processing unit comprising: an input optical fiber unit, an output optical fiber unit and a nonlinear all-optical modulator, the input optical fiber unit being used to propagate the input optical signal and a weighted optical beam therethrough; the nonlinear all-optical modulator being located upstream of the output optical fiber unit to be exposed to the interaction between the input optical signal and the weighted optical beam, the nonlinear all-optical modulator being configured to apply spatial modulation of the weighted optical beam to the optical field of the input optical signal via the interaction, thereby generating a spatially modulated optical field corresponding to the input optical signal, and allowing the spatially modulated optical field to propagate to a detection plane through the output optical fiber unit.

[0037] In some embodiments, the input fiber unit comprises a common input fiber for propagating both the input optical signal and the weighted optical beam. The nonlinear all-optical modulator may be located between the input fiber unit and the output fiber unit, in an output plane of the input fiber unit. In some other embodiments, the nonlinear all-optical modulator is completely integrated with the common input fiber, so that the input optical signal and the weighted optical beam experience the interaction with the nonlinear all-optical modulator during their propagation through the common input fiber; or the nonlinear all-optical modulator has a hybrid configuration, according to which the nonlinear all-optical modulator comprises a first nonlinear medium integrated with the common input fiber.

[0038] In some further embodiments, the nonlinear all-optical modulator includes at least a first nonlinear medium integrated with the common input optical fiber, so that the input optical signal and the weighted optical beam undergo the interaction with the first nonlinear medium during their propagation through the common input optical fiber, thereby applying spatial modulation of the weighted optical beam on the first axis to the input optical signal and generating a light field of the first axis modulated input optical signal, and the nonlinear all-optical modulator includes a second nonlinear medium at the output plane of the input optical fiber unit.

[0039] In some embodiments, the input fiber unit comprises a first input fiber and a second input fiber for propagating the input optical signal and the weighted optical beam, respectively. The nonlinear all-optical modulator is located between the input fiber unit and the output fiber unit, in an output plane of the input fiber unit.

[0040] The input fiber unit may include at least one input fiber configured as a GRIN fiber.The output fiber unit may also include at least one output fiber configured as a GRIN fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] For a better understanding of the subject matter disclosed herein and in order to illustrate how it may be implemented in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which: Figure 1A and Figure 1B is a schematic diagram of an optical processor system of the present disclosure, wherein: Figure 1A An optical processor system utilizing a nonlinear all-optical modulator housed external to the input fiber unit is shown, and Figure 1B An optical processor system utilizing an input fiber unit including a nonlinear all-optical modulator integrated within the input fiber unit is shown.

[0042] Figure 2A-2C Illustrated suitable for Figure 1A and Figure 1BDifferent configurations of optical processor units used in optical processing systems, wherein Figure 2A and Figure 2B An optical processor unit is shown having an input fiber unit and a nonlinear all-optical modulator located at the output end and / or inside the input fiber unit, the input fiber unit comprising a common fiber for the input optical signal and the weighted light beam propagation, and Figure 2C An optical processor unit with an input fiber unit having different optical fibers for input optical signal and weighted light beam propagation, respectively, and a nonlinear all-optical modulator at the output end of the input fiber unit is shown. DETAILED DESCRIPTION

[0043] refer to Figure 1A and Figure 1B , schematically illustrate two examples of an optical processor system 10 of the present disclosure, which is configured and operable to implement various data processing / computing tasks / functions. The system 10 is an optical fiber-based photonic processing system that can be used as an optical communication system or an optical computing system.

[0044] The optical processor system 10 comprises at least one optical / photonic processing unit / computing unit 12 configured to implement a predetermined processing task on an input optical signal IS. The processing unit 12 comprises an optical fiber (in some embodiments a multimode optical fiber) arrangement comprising an input optical fiber unit 12A comprising one or more input light propagation optical fibers for propagating the input optical signal IS and the weighted light beam WB therethrough and an output optical fiber unit 12C spaced apart from the input optical fiber unit along a general light propagation direction through the processing unit 12 towards a detection plane DP. The processing unit 12 further comprises a nonlinear all-optical modulator 12B.

[0045] The nonlinear all-optical modulator 12B may be a separate element located between the output end of the input fiber unit 12A and the input end of the output fiber unit 12C. In another example, the nonlinear all-optical modulator 12B may be implemented as a component of the input fiber unit. According to yet another example, the nonlinear all-optical modulator 12B may be configured as a hybrid structure, which includes a first nonlinear medium (a common input fiber through which the input optical signal and the weighted light beam propagate) that is integrated with the input fiber unit and a second nonlinear medium located at the output plane of the input fiber unit.

[0046] As described above, nonlinear all-optical modulators can be configured using any known suitable technology to achieve nonlinear all-optical effects. Some specific non-limiting examples of such optical modulators include: photoabsorbers (e.g., based on plasma dispersion effects), electro-optic modulators (based on the Kerr effect), photorefractive modulators (responding to interaction with light through changes in refractive index due to light-induced redistribution of electrons and holes), cross-phase modulation effects (the light intensity of one beam affects the phase change of another beam), soliton effects (nonlinear effects balance diffraction or dispersion).

[0047] In the following description, for simplicity, the nonlinear all-optical modulator is referred to as a light absorber. However, it should be understood that the principles of the technology disclosed herein are not limited to this specific example, so the term "light absorber" should be broadly interpreted to cover any known suitable type of nonlinear all-optical modulator.

[0048] exist Figure 1A In the example of , the light absorber 12B is implemented as a separate element located in the propagation path of the light output from the input fiber unit, which is located in the output plane OP of the input fiber unit 12A. The light absorber 12B can be in the form of a thin semiconductor film (silicon, germanium) or a Si core fiber.

[0049] exist Figure 1B In the example of FIG. 1 , the optical absorber 12B is integrated with the input optical fiber unit 12A. The optical absorber 12B can be implemented as a material constituting a core that can propagate the input optical signal IS and the weighted optical beam WB, such as a Si core. Therefore, the input optical fiber unit 12A operates to both propagate the input optical signal IS and the weighted optical beam WB and allow them to interact with the optical absorber 12B.

[0050] The light absorber 12B can be switched / activated from its passive state to an active state in which it operates as a spatial light modulator. This will be described in more detail further below.

[0051] The input optical fiber unit 12A is configured to receive an input optical signal IS of a predetermined wavelength λ1 and a weighted optical beam WB having at least one optical property different from the corresponding property of the input optical signal IS (e.g. wavelength, polarization, phase). In this non-limiting example, the weighted optical beam WB has a predetermined wavelength λ2 different from the wavelength λ1 of the input optical signal IS (λ1≠λ2). For example, λ1=1500nm, λ2=1000nm.

[0052] The input optical signal IS and the weighted optical beam WB propagate through the input optical fiber unit 12A (in a general propagation direction) towards the output plane OP.

[0053] The optical absorber 12B is exposed to interaction with the input optical signal IS and the weighted optical beam WB. Figure 1A In the example of , the light absorber element 12B is located in the output plane OP, so this interaction occurs when the input optical signal IS and the weighted light beam WB are incident on the light absorber element 12B when leaving the input optical fiber unit. Figure 1B In the example of FIG. 1 , the input optical signal IS and the weighted optical beam WB experience multiple interactions with the optical absorber 12B while propagating through the input optical fiber unit 12A.

[0054] The light absorber 12B may be excited / switched by interaction with the weighted light beam WB to apply spatial modulation to the input light signal IS interacting with the light absorber 12B, thereby generating a spatially modulated light field MLF corresponding to the input light signal IS.

[0055] More specifically, the interaction of the weighted light beam WB with the optical absorber 12B (which is a separate element at the output plane OP, or is integral with / extends along the input optical fiber through which both the input optical signal IS and the weighted light beam WB propagate) excites the optical absorber by inducing the generation of free charged carriers (electron-hole pairs), which are effectively absorbed by the optical absorber 12B, thereby generating a spatial modulation pattern within the optical absorber 12B. When the input optical signal IS interacts with the optical absorber 12B so excited, this affects the corresponding spatial modulation of the input optical signal IS, thereby generating a final modulated optical signal / field MLF. The modulated optical signal / field MLF can be transmitted through the optical absorber 12B.

[0056] It will be appreciated that the optical characteristics of the weighted light beam WB (eg, wavelength and intensity) may be selected such that the weighted light beam WB properly excites the light absorber 12B.

[0057] exist Figure 1A In the example of FIG. 1 , the optical absorber 12B is located in the propagation path of the light output from the input optical fiber unit 12A, in the output plane OP, and is therefore exposed to the interaction with the input optical signal IS and the weighted light beam WB emitted from the input optical fiber unit 12A. Figure 1B In the example, the core of the input optical fiber 12A is made of a light absorbing material and thus acts as a light absorber 12B, and the input optical signal IS and the weighted light beam WB experience multiple interactions with the light absorber 12B during their propagation through the input optical fiber unit 12A.

[0058] The output fiber unit 12C is configured to receive and propagate the spatially modulated light field SML to direct a light field indicative of the spatially modulated light field SML onto a detection plane DP accommodated at a predetermined position in accordance with a predetermined function / processing task to be implemented by the processing unit 12. As will be further described below, the input fiber unit 12A and the output fiber unit 12C are configured in accordance with the desired processing function / task to be implemented.

[0059] Therefore, the processing task to be performed by the optical processing unit 12 may be a predetermined function applied to the input optical signal IS involving a spatial modulation effect exerted on the input optical signal IS by the weighted optical beam WB via its interaction with the optical absorber 12B.

[0060] Such predetermined functions may be, for example, convolution, matrix multiplication, spatial filtering of a light field, etc. As will be further described below, the structure and length of the input fiber unit 12A and the structure and length of the output fiber unit 12B are appropriately selected to achieve the desired optical processing of light passing therethrough.

[0061] refer to FIG. 2A to FIG. 2C , FIG. 2A to FIG. 2C Different configurations of the optical processor unit 12 of the present disclosure for implementing various processing / computational tasks / functions on the input optical signal IS are illustrated. To facilitate understanding, in all examples described herein, the same reference numerals are used to identify similar components.

[0062] exist Figure 2A and Figure 2B In the illustrated processing unit, the input fiber unit 12A includes a common input fiber 14A, which is configured to receive and propagate both the input optical signal IS and the weighted optical beam WB. As described above, the input optical signal and the weighted optical beam differ from each other in at least one optical characteristic. In this non-limiting example, the input optical signal and the weighted optical beam have certain different wavelengths λ1 and λ2 (λ1≠λ2). The output fiber unit 12C includes the output optical fiber 14C.

[0063] exist Figure 2A In the example of FIG. 1 , the light absorber 12B is integrated with the optical fiber 14A (ie, the core of the optical fiber 14A is made of a light absorbing material), while in Figure 2B In the example of FIG. 1 , the light absorber 12B is a separate element located in the output plane OP at the output end of the optical fiber 14A.

[0064] Figure 2CAn optical processor unit 12 is illustrated, wherein an input fiber unit 12A comprises a first input fiber 14A and a second input fiber 14B, the first input fiber 14A and the second input fiber 14B being respectively configured to receive an input optical signal IS and a weighted light beam WB and propagate them toward an output plane OP, the output plane OP being accommodated at a predetermined position according to a predetermined function to be achieved. In this example, the light absorber 12B is a separate element located in the plane OP.

[0065] It should be understood that, as described above, the input optical signal IS and the weighted optical beam WB can propagate in the same optical fiber of the input optical fiber unit or in separate optical fibers, regardless of whether the predetermined function / task to be achieved involves the input optical signal IS and the weighted optical beam WB in the same domain (frequency domain and / or spatial domain) at the output of the input optical fiber unit, or involves the input optical signal IS and the weighted optical beam WB in different domains (frequency domain and / or spatial domain) at the output of the input optical fiber unit.

[0066] Since the input optical signal IS and the weighted optical beam WB have different wavelengths, their main Fourier planes are not at the same position. Therefore, propagating the input optical signal IS and the weighted optical beam WB through the same optical fiber of appropriately chosen length (and refractive index profile that can be adjusted, for example, via heating) allows to determine whether they leave the optical fiber in the same or different domains.

[0067] In both cases (i.e., a common fiber or different fibers of the input fiber unit 12A for propagating the input optical signal IS and the weighted optical beam WB), the optical absorber 12B may be located inside the input optical fiber or multiple input optical fibers. Furthermore, in the same domain operation mode, the interaction of the input optical signal IS and the weighted optical beam WB with the optical absorber 12B results in the multiplication of the input optical signal and the weighted optical beam.

[0068] As described above, in some embodiments, a hybrid configuration may be used, according to which the nonlinear all-optical modulator 12B includes a first nonlinear medium and a second nonlinear medium, one integral with the input fiber unit and the other located at the output plane of the input fiber unit. Figure 2A or Figure 2B This is achieved by using an input fiber unit configuration (i.e. a configuration that uses a common input fiber to propagate both the input optical signal IS and the weighted optical beam WB).

[0069] Therefore, although not specifically shown, Figure 2A In the example of , the modulator 12B shown as being located inside the common input fiber 14A will constitute the first nonlinear medium, and the second nonlinear medium will be located at the output plane OP. Figure 2BIn the example of FIG. 1 , the modulator 12B shown as being located at the output plane OP exhibits a second nonlinear medium, while the first nonlinear medium will be located inside the optical fiber 14A. During the propagation of the input optical signal IS and the weighted light beam WB through the common input optical fiber 14A, both and the first nonlinear medium ( Figure 2A The interaction of the input optical signal and the weighted optical beam WB on the first axis is applied to the optical field corresponding to the input optical signal by the interaction of the input optical signal and the weighted optical beam WB, and the modulated input optical signal and the weighted optical beam are combined with the second nonlinear medium ( Figure 2B 12B) exerts a weighted spatial modulation of the input optical signal on the second axis.

[0070] As described above, the input fiber optic unit 12A and the output fiber optic unit 12C are configured according to the predetermined functions / processing tasks to be performed.

[0071] In some embodiments, the optical processing unit 12 is configured to implement a convolution function. In this case, the processing unit 12 may have the above-mentioned FIG. 2A to FIG. 2C The general configuration shown in any of the examples of , wherein the optical fibers of the input fiber unit 12A and the output fiber unit 12B are graded-index (GRIN) fibers configured to apply a Fourier transform function to light passing therethrough.

[0072] More specifically, Figure 2A and Figure 2B The system configuration of the optical fiber 14A or Figure 2C Each optical fiber 14A and 14B in the system configuration is a GRIN fiber, which is dimensioned to perform a Fourier transform on the input optical signal IS and the weighted optical beam WB, i.e., the output plane OP is the Fourier plane relative to the optical input of the input GRIN fiber. Therefore, considering the use of an optical absorber 12B located outside the input optical fiber unit 12A, the input optical signal IS and the weighted optical beam WB are in the frequency / spectral domain when they leave the input optical fiber unit 12A.

[0073] like Figure 2BAs shown, the optical absorber 12B is housed in the output plane OP and is exposed to the interaction with the input optical signal IS and the Fourier transformed optical field of the weighted optical beam WB. As described above, the weighted optical beam WB (e.g., of a predetermined wavelength λ2) interacts with the optical absorber 12B and excites the optical absorber 12B while being effectively absorbed by the optical absorber, thereby applying a corresponding spatial modulation to the input optical signal IS interacting with the optical absorber 12B to generate a spatially modulated optical field MLF. The spatially modulated optical field MLF thus generated is the product of the input optical signal IS and the weighted optical beam WB in the frequency / spectral domain, which then undergoes an inverse Fourier transform when passing through the GRIN optical fiber 14C of the output optical fiber unit 12B, thereby generating the desired convolution function, namely the convolution of the optical signal IS with the weighted optical beam WB. The detection plane DP is the Fourier plane relative to the optical input of the optical fiber 14C.

[0074] exist Figure 2A In the example, as described above, the optical absorber 12B is integrated with the input optical fiber unit 12A. In this case, the input optical signal IS and the weighted optical beam WB propagate along the common input GRIN optical fiber 14A and experience multiple interactions with the optical absorber 12B. The modulated light field MLF obtained at the output plane OP of the input optical fiber unit 12A can correspond to the Fourier transform of multiple matrix multiplications of the input optical signal IS and the weighted optical beam WB.

[0075] The modulated light field MLF then undergoes an inverse Fourier transform while passing through the GRIN fiber 14C of the output fiber unit 12B, thereby generating the desired convolution function. The detection plane DP is the Fourier plane relative to the light input of the fiber 14C.

[0076] Therefore, in these examples, the convolution function is implemented by using GRIN fiber and optical absorber, which provide the interaction of Fourier transform of input optical signal IS and weighted optical beam WB with optical absorber 12B, and continuous Fourier transform of spatial modulated light field MLF corresponding to the weighted input optical signal IS.

[0077] In some other embodiments, the processing function / task is a signal multiplication of the input optical signal IS and the weighted optical beam WB performed via an imaging process. Both the input optical signal and the weighted optical beam have the same spatial domain. In such embodiments, either GRIN fiber or standard optical fiber can be used. Considering the use of standard optical fiber, one can use FIG. 2A to FIG. 2CAny of the above configurations of the processing unit illustrated in , wherein the optical fibers of the input fiber unit 12A and the output fiber unit 12C are configured as imaging fibers, that is, the output plane OP is an image plane with respect to the light input into the input fiber unit 12A, and the detection plane DP is an image plane with respect to the light input into the output fiber unit 12C. If a GRIN fiber is used as a common input fiber for propagating both the input signal and the weighted light beam, the GRIN fiber is appropriately customized so that both light beams exit in the imaging plane.

[0078] exist Figure 2B and Figure 2C In a configuration in which the optical absorber 12B is placed in a plane OP outside the optical fiber unit 12A, both the input optical signal IS and the weighted optical beam WB are guided by the input optical fiber unit 12A toward the optical absorber 12B to interact with the optical absorber 12B. The interaction of the optical absorber 12B with the weighted optical beam WB excites / switches the optical absorber to generate a spatial mode corresponding to the spatial mode of the weighted optical beam WB in the optical absorber, while effectively absorbing the beam, and applying a corresponding spatial modulation to the input optical signal IS transmitted through the optical absorber 12B to generate a modulated light field MLF, which propagates to the detection plane DP through the imaging optical fiber of the output optical fiber unit 12C. The resulting image has a spatial intensity distribution corresponding to the product of the matrix multiplication of the input optical signal IS and the weighted optical beam WB.

[0079] Therefore, in this case, the predetermined processing task implemented by the processing unit 10 can be the signal multiplication between the input light signal IS and the weighted light beam WB, which is generated by imaging the input light signal and the weighted light beam onto a light absorber, which generates a modulated light field MLF via interaction with the two light fields, and the modulated light field MLF is continuously imaged on the detection plane DP.

[0080] In some other embodiments, the predetermined processing task implemented by the processing unit 10 comprises filtering selected spatial frequencies of the input optical signal IS. Figure 2CThe processing unit configuration of the embodiment is substantially similar to that of the embodiment, that is, the input fiber unit 12A includes a first optical fiber 14A and a second optical fiber 14B, which are respectively used to propagate the input optical signal IS and the weighted light beam WB to the optical absorber 12B at the output plane OP outside the input fiber unit 12A. However, for the purpose of this embodiment, the first input optical fiber 14A is a GRIN optical fiber, which is dimensioned to perform Fourier transform on the input optical signal IS, and the second input optical fiber 14B is an imaging optical fiber. The output plane OP is a Fourier plane relative to the light input to the first input optical fiber 14A and an image plane relative to the light input into the second input optical fiber 14B. In addition, the output optical fiber 14C is a GRIN optical fiber that performs Fourier transform on the light passing therethrough.

[0081] The optical absorber 12B housed in the output plane OP is exposed to the interaction with the optical fields of different domains: the Fourier transform of the input optical signal IS and the spatial pattern of the weighted optical beam WB. The weighted optical beam WB interacts with the optical absorber 12B to excite / switch the optical absorber 12B to its modulation state, so that the weighted optical beam WB, while being effectively absorbed by the optical absorber 12B, produces a spatial modulation pattern in the weighted optical beam WB. In this way, the interaction of the input optical signal IS with the optical absorber 12B affects the amplification of selected spatial frequencies of the input optical signal IS and allows the transmission of these frequencies, while attenuating and absorbing other spatial frequencies of the input optical signal, thereby forming a modulated / filtered light field MLF.

[0082] The modulated light field MLF is propagated through the output GRIN fiber 14C to inverse Fourier transform the modulated light field MLF when it is directed onto the detection plane DP. The detection plane DP is the Fourier plane relative to the light input of the GRIN fiber 14C. More specifically, when the modulated light field MLF enters the output GRIN fiber 14C, it is in the frequency domain. The output GRIN fiber 14C performs a Fourier transform on the modulated light field MLF, which is then inverted / shifted to a time / space domain that includes only the selected spatial frequencies.

[0083] Thus, the present disclosure provides a fiber-based all-optical photonic / optical processing unit capable of performing various processing tasks such as convolution, matrix multiplication, spatial filtering of light fields, etc. Such a processing unit may form a building block of an optical processor system.

Claims

1. An optical processor system, comprising at least one optical processing unit, wherein the at least one optical processing unit is configured to perform a predetermined processing task on an input optical signal, wherein the optical processing unit comprises an optical fiber device, wherein the optical fiber device defines: an input fiber unit configured to propagate the input optical signal and a weighted light beam having at least one optical characteristic different from the input optical signal towards an output plane of the input fiber unit, the output plane being positioned according to the predetermined function to be achieved, an output fiber unit spaced apart from the output plane of the input fiber unit in a general direction of light propagation through the optical processing unit and configured to propagate light to a detection plane, and a nonlinear all-optical modulator located upstream of the output optical fiber unit so as to be exposed to interaction with the light field corresponding to the input optical signal and the light field corresponding to the weighted optical beam, the nonlinear all-optical modulator being switchable to a spatial modulation state by interaction with the light field corresponding to the weighted optical beam, thereby applying spatial modulation of the weighted optical beam to the light field corresponding to the input optical signal, thereby generating a spatially modulated light field corresponding to the input optical signal, and allowing the spatially modulated light field to propagate through the output optical fiber unit to the detection plane.

2. The optical processor system according to claim 1, wherein: The nonlinear all-optical modulator of the optical processing unit is accommodated in the output plane and is exposed to interaction with the light field corresponding to the input light signal and the light field corresponding to the weighted light beam, thereby applying the spatial modulation of the weighted light beam to the light field corresponding to the input light signal and generating the spatially modulated light field corresponding to the input light signal.

3. The optical processor system of claim 2, wherein: The input fiber unit of the optical processing unit comprises a common input fiber configured to propagate both the input optical signal and the weighted optical beam.

4. The optical processor system of claim 2, wherein: The input fiber unit of the optical processing unit comprises a first input fiber and a second input fiber configured to propagate the input optical signal and the weighted light beam, respectively.

5. The optical processor system of claim 1, wherein: The input fiber unit of the optical processing unit includes a common input fiber configured to propagate both the input optical signal and the weighted optical beam, and the nonlinear all-optical modulator is integrated with the common input fiber, so as to apply the spatial modulation of the weighted optical beam to the optical field corresponding to the input optical signal during the propagation of the input optical signal and the weighted optical beam through the common input optical fiber, thereby generating the spatially modulated optical field corresponding to the input optical signal.

6. The optical processor system of claim 5, wherein: The core of the common input optical fiber is configured as the nonlinear all-optical modulator.

7. The optical processor system of claim 1, wherein: The input fiber unit of the optical processing unit includes a common input fiber configured to propagate both the input optical signal and the weighted optical beam, and the nonlinear all-optical modulator includes: a first nonlinear medium and a second nonlinear medium, the first nonlinear medium being integrated with the common input fiber, thereby applying spatial modulation of the weighted optical beam on a first axis to an optical field corresponding to the input optical signal during the propagation of the input optical signal and the weighted optical beam through the common input optical fiber, and the second nonlinear medium being located at the output end of the common input optical fiber, thereby applying spatial modulation of the weighted optical beam on a second axis to the input optical signal, thereby generating the spatially modulated optical field corresponding to the input optical signal.

8. The optical processor system of claim 1, wherein: The input fiber unit comprises at least one graded-index (GRIN) optical fiber configured to apply a Fourier transform function to at least one of the input optical signal and the weighted optical beam, the output plane being a Fourier plane relative to an optical input of the input fiber unit for the at least one of the input optical signal and the weighted optical beam, and The output fiber unit comprises a GRIN fiber configured to apply a continuous Fourier transform function to the spatially modulated light field passing through the GRIN fiber, the detection plane being a Fourier plane of light input to the GRIN fiber of the output fiber unit for the spatially modulated light field.

9. The optical processor system of claim 8, wherein: The input optical signal and the weighted optical beam propagate through a first GRIN fiber and a second GRIN fiber of the input optical fiber unit, and the first GRIN fiber and the second GRIN fiber are configured to apply the Fourier transform to the input optical signal and the weighted optical beam, respectively.

10. The optical processor system of claim 8, wherein: The nonlinear all-optical modulator of the optical processing unit is accommodated in the output plane and is exposed to interaction with the light field corresponding to the input light signal and the light field corresponding to the weighted light beam, thereby applying the spatial modulation of the weighted light beam to the light field corresponding to the input light signal and generating the spatially modulated light field corresponding to the input light signal.

11. The optical processor system of claim 8, wherein: The input optical signal and the weighted optical beam propagate through a same GRIN optical fiber, and the same GRIN optical fiber is configured to apply the Fourier transform to both the input optical signal and the weighted optical beam.

12. The optical processor system of claim 8, wherein: The input optical signal and the weighted optical beam propagate through the same GRIN fiber, and the same GRIN fiber is configured to apply the Fourier transform only to the input optical signal.

13. The optical processor system of claim 11, wherein: The nonlinear all-optical modulator is integrated in the GRIN optical fiber, thereby applying the spatial modulation of the weighted optical beam to the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN optical fiber and generating the spatially modulated optical field corresponding to the input optical signal.

14. The optical processor system of claim 12, wherein: The nonlinear all-optical modulator is integrated in the GRIN optical fiber, thereby applying the spatial modulation of the weighted optical beam to the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN optical fiber and generating the spatially modulated optical field corresponding to the input optical signal.

15. The optical processor system of claim 12, wherein: The nonlinear all-optical modulator comprises: a first nonlinear medium and a second nonlinear medium, wherein the first nonlinear medium is integrated with the same GRIN optical fiber of the input optical fiber unit, so as to apply spatial modulation of the weighted optical beam on a first axis to the optical field corresponding to the input optical signal during the propagation of the input optical signal and the weighted optical beam through the common input optical fiber, and the second nonlinear medium is located at the output end of the same GRIN optical fiber of the input optical fiber unit, so as to apply spatial modulation of the weighted optical beam on a second axis to the input optical signal, thereby generating the spatially modulated optical field corresponding to the input optical signal.

16. The optical processor system of claim 13, wherein: The nonlinear all-optical modulator comprises: a first nonlinear medium and a second nonlinear medium, wherein the first nonlinear medium is integrated with the same GRIN optical fiber of the input optical fiber unit, so as to apply spatial modulation of the weighted optical beam on a first axis to the optical field corresponding to the input optical signal during the propagation of the input optical signal and the weighted optical beam through the common input optical fiber, and the second nonlinear medium is located at the output end of the same GRIN optical fiber of the input optical fiber unit, so as to apply spatial modulation of the weighted optical beam on a second axis to the input optical signal, thereby generating the spatially modulated optical field corresponding to the input optical signal.

17. The optical processor system of claim 8, wherein: The predetermined processing task implemented by the processing unit is the convolution between the input optical signal and the weighted optical beam, the convolution resulting from the interaction between the Fourier transform of the input optical signal and the weighted optical beam and the spatially modulated light field generated by the nonlinear all-optical modulator, and the continuous Fourier transform of the spatially modulated light field corresponding to the input optical signal.

18. An optical processor system according to claim 17, wherein: The input optical signal and the weighted optical beam propagate through a first GRIN fiber and a second GRIN fiber of the input optical fiber unit, and the first GRIN fiber and the second GRIN fiber are configured to apply the Fourier transform to the input optical signal and the weighted optical beam, respectively.

19. An optical processor system according to claim 18, wherein: The nonlinear all-optical modulator of the optical processing unit is accommodated in the output plane and is exposed to interaction with the light field corresponding to the input light signal and the light field corresponding to the weighted light beam, thereby applying the spatial modulation of the weighted light beam to the light field corresponding to the input light signal and generating the spatially modulated light field corresponding to the input light signal.

20. The optical processor system of claim 17, wherein: The input optical signal and the weighted optical beam propagate through a same GRIN optical fiber, and the same GRIN optical fiber is configured to apply the Fourier transform to both the input optical signal and the weighted optical beam.

21. An optical processor system according to claim 20, wherein: The nonlinear all-optical modulator is integrated in the GRIN optical fiber, thereby applying the spatial modulation of the weighted optical beam to the input optical signal during the propagation of the weighted optical beam and the input optical signal through the GRIN optical fiber and generating the spatially modulated optical field corresponding to the input optical signal.

22. The optical processor system of claim 8, wherein: The predetermined processing task implemented by the processing unit is filtering selected spatial frequencies of the input optical signal, the filtering resulting from the interaction of the Fourier transform of the input optical signal and the weighted optical beam with the nonlinear all-optical modulator, and the continuous Fourier transform of the spatially modulated light field corresponding to the input optical signal.

23. An optical processor system according to claim 22, wherein: The input optical signal and the weighted optical beam propagate through a first optical fiber and a second optical fiber, respectively, at least the first optical fiber is a GRIN fiber configured to achieve Fourier transform of the input optical signal, and the second optical fiber is configured as an imaging fiber for the weighted optical beam.

24. An optical processor system according to claim 23, wherein: The nonlinear all-optical modulator of the optical processing unit is accommodated in the output plane to be exposed to interaction with a light field corresponding to the input optical signal and a light field corresponding to the weighted light beam.

25. The optical processor system of claim 22, wherein: The input optical signal and the weighted optical beam propagate through a same GRIN fiber of the input optical fiber unit, the same GRIN fiber being configured to apply the Fourier transform to the input optical signal and being configured as an imaging fiber with respect to the weighted optical beam.

26. An optical processor system according to claim 25, wherein: The nonlinear all-optical modulator is integrated within the GRIN fiber so as to apply the spatial modulation of the weighted optical beam to the Fourier transform of the input optical signal during propagation of the weighted optical beam and the input optical signal through the GRIN fiber.

27. The optical processor system of claim 1, wherein: The predetermined processing task implemented by the processing unit is the signal multiplication between the input optical signal and the weighted optical beam, the signal multiplication resulting from the interaction between the light field corresponding to the input optical signal and the light field corresponding to the weighted optical beam and the nonlinear all-optical modulator, and the continuous imaging of the spatially modulated light field corresponding to the input optical signal on the detection plane, the input optical fiber unit is configured such that the output plane is an image plane for the optical input of the input optical fiber unit relative to both the input optical signal and the weighted optical beam, and the output optical fiber unit is configured such that the detection plane is an imaging plane for the optical input of the output optical fiber unit relative to the input optical signal.

28. The optical processor system of claim 1, wherein: The nonlinear optical modulator is configured and operable based on one of the following effects: plasma dispersion effect, photorefractive effect, cross-phase modulation effect, soliton effect, Kerr effect.

29. An optical processing unit, configured to perform a predetermined processing task on an input optical signal, the optical processing unit comprising: an input fiber unit, an output fiber unit, and a nonlinear all-optical modulator, wherein the input fiber unit is used to propagate the input optical signal and the weighted optical beam therethrough; The nonlinear all-optical modulator is located upstream of the output optical fiber unit to be exposed to the interaction between the input optical signal and the weighted optical beam, and the nonlinear all-optical modulator is configured to apply spatial modulation of the weighted optical beam to the optical field of the input optical signal via the interaction, thereby generating a spatially modulated optical field corresponding to the input optical signal, and allowing the spatially modulated optical field to propagate through the output optical fiber unit to a detection plane.

30. The optical processing unit according to claim 29, wherein: The input fiber unit comprises a common input fiber for propagating both the input optical signal and the weighted optical beam.

31. The optical processing unit according to claim 30, wherein: The nonlinear all-optical modulator is located between the input fiber unit and the output fiber unit, in the output plane of the input fiber unit.

32. The optical processing unit of claim 30, wherein: The nonlinear all-optical modulator is integrated with the common input optical fiber such that the input optical signal and the weighted optical beam undergo the interaction with the nonlinear all-optical modulator during their propagation through the common input optical fiber.

33. The optical processing unit according to claim 30, wherein: The nonlinear all-optical modulator comprises at least a first nonlinear medium integrated with the common input optical fiber, so that the input optical signal and the weighted optical beam undergo the interaction with the first nonlinear medium during their propagation through the common input optical fiber, thereby applying spatial modulation of the weighted optical beam on a first axis to the input optical signal and generating a first-axis modulated optical field of the input optical signal.

34. The optical processing unit of claim 31, wherein: The nonlinear all-optical modulator also includes a second nonlinear medium at the output plane of the input optical fiber unit, so that the first-axis modulated light field and the weighted light beam experience additional interaction with the second nonlinear medium at the output plane, and the additional interaction thereby applies the spatial modulation of the weighted light beam on the second axis to the first-axis modulated light field of the input optical signal.

35. The optical processing unit of claim 29, wherein: The input fiber unit comprises a first input fiber and a second input fiber for propagating the input optical signal and the weighted light beam, respectively, and wherein the nonlinear all-optical modulator is located between the input fiber unit and the output fiber unit in an output plane of the input fiber unit.

36. The optical processing unit of claim 29, wherein: The input fiber unit comprises at least one input optical fiber configured as a GRIN fiber.

37. An optical processing unit according to claim 36, wherein: The output fiber unit comprises at least one output fiber configured as a GRIN fiber.

Images