Waveguide network

Abstract

A multimode optical waveguide network includes a parent waveguide and a plurality of child waveguides. Each waveguide is a multimode optical waveguide having a first surface region, a plurality of second surface regions, and at least one guide element attached to or embedded within the waveguide surface, each second surface region of the parent waveguide being optically coupled to a surface region of the first surface region corresponding sub-waveguide. The guiding element of the parent waveguide is arranged to direct a light beam from its first surface area towards any selected one of its plurality of second surface areas, or to direct a light beam from any selected one of its plurality of second surface areas towards its first surface area. The guide element (s) of each waveguide may be configured to select the second surface area of the waveguide and / or to select the second surface area of the waveguide via modulation of at least one beam characteristic in response to the at least one beam characteristic.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application date of February 22, 2021, application number 202180024037.6, and subject name “Waveguide Network”. Technical Field

[0002] The present disclosure relates generally to optical waveguide technology. Background Art

[0003] An optical waveguide is an optical element that can guide a beam of light by total internal reflection. A waveguide can be "multimode", with physical dimensions sufficient to support a range of "modes" (i.e., spatial paths through the waveguide for a given channel, which correspond, for example, to different directions of propagation). This is in contrast to simple single-mode optical waveguides, such as the thin optical fibers used in fiber optic systems, which are intended to confine light entering the fiber to essentially a single mode of propagation. Single-mode optical waveguides can only transmit data using amplitude, phase, or frequency modulation, while multimode optical waveguides allow more data (e.g., an entire image with potentially millions of pixels) to be transmitted through angular variations within the waveguide. In other words, multimode waveguides provide greater bandwidth by increasing angular and / or spatial diversity, by providing multiple optical paths from emitter to detector for any given channel (different paths corresponding to different modes of propagation). Summary of the invention

[0004] The Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detailed Description below. The Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The claimed subject matter is also not limited to implementations that solve any or all of the disadvantages mentioned herein.

[0005] A multimode optical waveguide network includes a parent waveguide and a plurality of daughter waveguides. Both the parent waveguide and the daughter waveguide are multimode optical waveguides, which have a first surface area, a plurality of second surface areas, and at least one guiding element attached to the waveguide surface or embedded in the waveguide, each second surface area of ​​the parent waveguide is optically coupled to the first surface area of ​​a corresponding daughter waveguide in the daughter waveguide. At least one guiding element of the parent waveguide is arranged to guide a light beam from its first surface area to any selected second surface area of ​​its plurality of second surface areas, or to guide a light beam from any selected second surface area of ​​the plurality of second surface areas to its second surface area, the light beam is coupled into or received from the corresponding daughter waveguide through the second surface area of ​​the parent waveguide and the first surface area of ​​the corresponding daughter waveguide, the first surface area of ​​the corresponding daughter waveguide is optically coupled to the second surface area of ​​the parent waveguide, and at least one guiding element of each daughter waveguide is arranged to guide a light beam from its first surface area to any selected second surface area of ​​its plurality of second surface areas, or to guide a light beam from any selected second surface area of ​​its plurality of second surface areas to its first surface area. The at least one guiding element of each waveguide may be configured to select the second surface area of ​​the waveguide and / or to select the second surface area of ​​the waveguide in response to at least one beam characteristic by modulation of at least one beam characteristic.

[0006] The present multimode waveguide network supports more flexible spatial multiplexing in multiple data transmission contexts across one or more spatial dimensions.

[0007] An example application of the present waveguide network is in a holographic data storage / retrieval system. Such a system would typically provide spatial multiplexing on the holographic recording medium, i.e., being able to write / read different physical sub-volumes of the medium by some form of mechanical actuator to move the medium relative to, for example, a read / write head of a moving medium system (from which input and reference beams are emitted and at which output beams are detected) or relative to a read / write head of the medium. This in turn limits the speed of data writing / reading as well as the scalability and reliability of such systems. One or more of the present multimode optical waveguide networks can be used to provide such multiplexing without the need for such mechanical actuators, where different areas can be read or written to control guiding elements and / or modulated beams. In this case, the multimode capability of the waveguide can, for example, be used to read / write an entire image simultaneously.

[0008] Other examples include optical communications or optical computing, where multimode waveguide networks can be used to multiplex, for example, different transmitters / receivers, signal converters / processors, optical processors, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] For a better understanding of the present disclosure, and to show how embodiments of the present disclosure may be implemented, reference is made to the following drawings, by way of example only, in which:

[0010] Figure 1A and 1B shows a schematic perspective view of a holographic recording medium;

[0011] Figure 2A shows a schematic perspective view of a holographic storage system including a set of waveguides that can be used to direct light beams to / from different sub-volumes of a holographic recording medium to provide spatial multiplexing on the medium;

[0012] Figure 2B , Figure 2C and Figure 2D A plan view and an alternate side view of the system during a write interval are shown, respectively;

[0013] Figure 2E-2G shows plan views and alternating side views during a read interval;

[0014] Figure 3A-3D Schematic side views of active light pipes showing various configurations;

[0015] Figure 3E and Figure 3F shows a plan (cross-sectional) view of an active light pipe;

[0016] Figure 4A and Figure 4B shows alternate side views of (portions of) an optical waveguide network;

[0017] Figure 5 A schematic diagram showing an example of a multi-waveguide network for multiplexing on multiple pieces of holographic storage media;

[0018] Fig. 6A An example of a transmission system for providing input and reference beams in a holographic storage system is shown; Figure 6B A variation of the launch system with simplified optics is shown;

[0019] Figure 7 An example of a data retrieval system using spatial coherence detection to measure the light field of an output beam and signal processing to mitigate waveguide distortion in the measured light field is shown;

[0020] Figure 8 A functional block diagram representing functions performed within a holographic storage system is shown;

[0021] Fig. 9 Another holographic storage system is shown, wherein at least one waveguide network is used for spatial multiplexing on a two-dimensional holographic recording medium slab;

[0022] Fig. 10A and Fig. 10BIt shows how to use passive steering elements to achieve spatial multiplexing, where the spatial multiplexing is achieved by modulating the characteristics of the light beam;

[0023] Fig.11A and Fig. 11B A light pipe showing passive filters with different frequency responses; and

[0024] Fig.12 An example of a waveguide network with three hierarchical structures is shown. DETAILED DESCRIPTION

[0025] An example application of the waveguide networks taught herein is holographic storage. Holographic storage is a form of computer storage in which information is recorded in a photosensitive holographic recording medium by exposing the medium to an optical pattern. For example, a region (subvolume) of the medium may be exposed to an optical interference pattern caused by interference between a reference beam and an input beam embedded with a set of data. For example, the beam may be a laser beam generated using a single laser and a beam splitter. Spatial light modulation (SLM) may be used to embed a data set into an input beam, for example, an image encoding the set of data may be spatially modulated into the input beam. For the avoidance of doubt, the terms "light", "optical", etc. herein are not limited to visible light. For example, holographic storage may be achieved using infrared or ultraviolet beams within the invisible portion of the electromagnetic spectrum.

[0026] With sufficient beam power and exposure time, the optical interference pattern results in a persistent change of state within the sub-body (at which point the interference pattern is referred to herein as persistently recording or writing the sub-body). The changed state of the sub-body is such that when the sub-body is later exposed to a substantially matching reference beam, the interaction between the matching reference beam and the sub-body produces an output beam that substantially matches the original input beam, whereby the data set originally embedded in the input beam can be recovered from the output beam (this may be referred to herein as reading the recorded pattern).

[0027] Instead of storing individual bits as discrete units, a single interference pattern can encode a large number (e.g., millions) of bits. For example, a data set could be a million-pixel image embedded in an input beam. Furthermore, by exploiting the sensitivity of certain forms of holographic recording media to small changes in the angle of the reference beam, many (e.g., hundreds or thousands) of such patterns can be recorded to the same subvolume. For such media, when an interference pattern is created using a reference beam at a given angle, the recorded pattern can only be read using a reference beam that closely matches the reference beam originally used to create it. This effect can be exploited to record multiple patterns (encoding different data sets) to the same subvolume at different reference beam angles. In theory, data storage capacity is limited only by the wavelength of the beam, potentially reaching hundreds of megabytes per cubic millimeter for red light and tens of gigabytes for ultraviolet light. In practice, there may be other limiting factors, but there is still great potential for high-density data storage.

[0028] To achieve spatial multiplexing on one or more holographic storage media in a manner that reduces or eliminates the need for mechanical motion, "active" light guides, "passive" light guides, or a combination of active and passive light guides may be used. Note that the terms "waveguide" and "light guide" are used interchangeably herein.

[0029] An "active light guide" refers to a waveguide having one or more active switching elements or other guiding elements attached to or within the body of the waveguide, which in turn are configurable (i.e. have variable optical properties) to achieve either "one-to-many" optical transmission, i.e. light is directed from a first surface area to one of a plurality of possible second surface areas (in which case the first surface area acts as an input coupling area and the second surface area acts as an output coupling area) or "many-to-one" optical transmission, i.e. light can be directed from any one of the second surface areas (now acting as an input coupling area) to the same first surface area (now acting as an output coupling area). The term "passive light guide" refers to a light guide having guiding elements that have different optical sensitivities (e.g. different wavelength and / or polarization sensitivities), so that a similar effect can be achieved by changing the optical properties or the light beam (e.g. changing its wavelength, polarization, etc. so that it is guided along different routes by guiding elements with different wavelength / polarization responses, etc.; e.g. using tunable lasers). The term "passive light guide" is simply a convenient representation of what is meant by the fact that in this case the guiding element does not need to be active - however, optical elements with different optical sensitivities (e.g. different wavelength and / or polarization sensitivities, etc.) may be used in this context (i.e. the guiding element may be active and have different optical sensitivities).

[0030] A digital image (or data encoded as a digital image) can be propagated as a light beam along an active or passive light guide. The guiding elements of an active light guide can be individually controlled to transmit or reflect an incident light beam.

[0031] Many such light guides (active, passive, or a combination of both types) can be combined in various geometries to create a switching network that can be used to direct light beams and images to one of many addressable locations in one or more spatial dimensions. For example, the input to the light guide can be created using a spatial light modulator (SLM) and the output read on a CCD (charge coupled device). Phase interference and noise can be corrected using a combination of optical and computational techniques, including machine learning techniques, which would involve learning one or more signal processing parameters from training data. Certain embodiments use coherent detection in conjunction with such techniques to provide more effective waveguide distortion mitigation.

[0032] Compared to optical switches and optical fibers of the type traditionally used for optical data communications, the described embodiments use light pipes that are capable of transmitting an entire image at once. This takes advantage of the high resolution of optical devices available today, such as SLMs and digital cameras. These devices have millions of pixels and can encode and decode megabytes of data. This allows high bandwidth transmission even for conservative switching rates for the SLM, camera, and active light pipe elements (in the case of active light pipes) or beam optical properties (in the case of passive light pipes). In addition, applications such as holographic storage require interference between multiple beams, at least one of which is modulated by an image. In holographic storage, the use of active light pipes allows the beams and images to be effectively controlled and interfered at any desired location in the holographic storage medium. As previously described, the benefit of simplicity can be achieved using passive light pipes, where switching is instead applied at the transmitter level.

[0033] The light guides described below are "multimode" waveguides whose physical dimensions are sufficient to support a range of "modes" (i.e., spatial paths through the waveguide, corresponding, for example, to different directions of propagation, for a given channel). This is different from simple single-mode optical waveguides, such as the thin optical fibers used in fiber optic systems, which are intended to confine light entering the fiber to essentially a single mode of propagation. Single-mode optical waveguides can only transmit data using amplitude, phase, or frequency modulation, while multimode optical waveguides allow more data (e.g., an entire image with potentially millions of pixels) to be transmitted through angular variations within the waveguide. In other words, multimode waveguides provide greater bandwidth by increasing angular and / or spatial diversity, which is achieved by providing multiple optical paths from emitter to detector for any given channel (different paths corresponding to different propagation modes).

[0034] Another aspect disclosed herein is a holographic data storage system that uses one or more waveguide networks to perform spatial multiplexing (i.e., reading from and writing to different sub-volumes of the medium) on a holographic recording medium without requiring any relative mechanical motion between the medium and the waveguide network. An example of such a system is described below, which uses active and / or passive light guides. In the described example, a multimode waveguide can be used to carry an entire digital image to / from the holographic recording medium simultaneously, or to carry a reference beam at one of multiple possible angles.

[0035] However, the optical waveguide networks taught herein are not limited in their application to holographic storage. Other applications include, for example, optical communications and optical computing.

[0036] Active Light Pipe:

[0037] Figure 3A-3D A schematic side view of an example form of an active light pipe 300 having a particular physical structure is shown. As will be appreciated, this is merely one example of a suitable physical structure that may provide the desired optical configurability. Further examples are considered below.

[0038] The active light pipe 300 is shown as having at least a first surface area 300-0 and a plurality of active switches in the form of switchable Bragg gratings (SBGs), which may be on the surface or embedded in the body. In this example, two such SBGs 300-1, 300-2 are shown on a first surface 300-S1 of the waveguide 300, but it should be understood that a greater number of SBGs may be provided at suitable locations on the surface 300-S1 of the surface 300 and / or embedded in the body of the waveguide 300. Each SBG 300-1, 300-2 may be individually controlled to change its reflection / transmission characteristics, thereby transmitting or reflecting an incident light beam. The SBGs 300-1, 300-2 form respective surface areas of the active light pipe 300, at which light may enter the waveguide 300 (incoupling) or leave the waveguide 300 (outcoupling), depending on how the waveguide 300 is used.

[0039] The first surface region 300 - 0 is an end region of the waveguide 300 , from which a first side surface 300 - S1 of the waveguide extends along the axis 301 of the waveguide 300 .

[0040] Figure 3E and Figure 3FEach shows a cross-sectional view of a waveguide 300, from which it can be seen that, in this example, the cross section of the waveguide 300 has a rectangular shape with four side surfaces 300-S1, 300-S2, 300-S2, 300-S4 extending along the axis 301 of the waveguide 300. In this example, the SBGs 300-1, 300-2 are both located along the first side surface 300-S1, as shown in the figure, of course, in general, such SBGs can be attached to multiple surfaces of the waveguide 300 depending on the application.

[0041] The SBGs 300-1, 300-2 are positioned along the first side surface of the waveguide 300-S1, increasingly farther from the first region 300-0, wherein the first SBG 300-1 is positioned closest to the first region 300-0.

[0042] Figure 3A , Figure 3B and Figure 3E A "one-to-many" use case is depicted, where the first surface region 300-0 acts as an incoupling region of the SBG, and the second surface regions 300-1, 300-2 act as outcoupling regions. As an example, FIG3 shows a first ray 304 coupled into the waveguide 300 via the incoupling region 300-0. In this example, the first surface region 300-0 is angled relative to the side surfaces 300-S1, ..., 300-S4 so that the first ray 304 can pass through the first surface region 300-0 into the waveguide body 300, thereby being sufficient to achieve total internal reflection at each side surface 300-1, ..., 300-4 within the waveguide 300.

[0043] Each of the SBGs 300-1, 300-2 may be configured to change it between a reflective state and a transmissive state. Figure 3A A configuration is shown in which the first SBG 300-1 is in a reflective state, causing incident light ray 300 to be reflected therefrom back into the waveguide 300 and guided along the waveguide 300 until reaching the second SBG 300-2. The SBG 300-2 is shown in a transmissive state, causing light ray 304 to be diffracted out of the waveguide 300 by the second SBG 300-2 and thereby coupled out of the waveguide 300 via a surface region of the second SBG 300-2. This configuration of the SBGs 300-1, 300-2 creates a "channel" through the waveguide 300 between the first surface region 300-0 and the surface region of the second SBG 300-2.

[0044] In contrast, Figure 3BThe first SBG 300-1 is shown in a transmissive state. Therefore, once the first light ray 304 reaches the first SBG 300-1, it is instead diffracted out of the waveguide 300 via the first SBG 300-1 and is in turn coupled out of the waveguide 300 via the surface region of the first SBG 300-1. This configuration creates a channel through the waveguide 300 between the first surface region 300-0 and the surface region of the first SBG 300-1.

[0045] In this way, a first light ray 304 may be directed from the first region 300-0 through the waveguide 300 and exit the waveguide 300 at a surface region of either SBG 300-1, 300-2. Although described with respect to only two SBGs 300-1, 300-2 for simplicity, it will be appreciated that the same principles may be applied to a greater number of SBGs.

[0046] Figure 3E It is shown how the first ray 304 propagates from some or all of the side surfaces 300 - S1 , . . . , 300 - S4 via TIR when viewed in cross-section, depending on the angle of the first ray 304 .

[0047] like Figure 3C , Figure 3D and Figure 3F As shown, many-to-one optical transmission is also possible using the depicted active light pipe 300.

[0048] Figure 3C Shown with Figure 3A Same SBG configuration. The only difference is how the waveguide 300 is used: a second ray 308 is now shown incident on the second SBG 300-2 from an external source (not shown). With the second SBG in the transmissive state, the second ray 308 is diffracted into the waveguide 300 via the second SBG (now providing incoupling at its surface area), from which it is guided through the waveguide 300 to the first surface area 300-0 (now an outcoupling area); this includes reflection from the first SBG 300-1, which is now in the reflective state. The reflective state of the first SBG 300-1 prevents the ray 308 from leaving the waveguide via the first SBG 300-1. Furthermore, any external ray 309 that may happen to be incident on the first SBG 300-1 will be substantially reflected away from it and therefore will not enter the waveguide 300.

[0049] Figure 3D Shown with Figure 3BSame configuration, but now a second ray 308 is incident on the first SBG 300-1 from an external source. The first SBG 300-1 is in a transmissive state, where a third ray 310 enters the waveguide 300 by diffraction and is guided to the first surface area 300-0.

[0050] Figure 3F The second ray 308 is shown to propagate within the waveguide 300 in cross section and is Figure 3E The same description applies here, except the rays are in the opposite direction.

[0051] The above description assumes perfect reflectivity / transmittance of the SBG in the transmission / reflection state. As will be appreciated, this is not an absolute requirement in practice, and the system will have a certain tolerance for imperfections in the SBGs 300-1, 300-2 and more generally in the waveguide 300. Suitable signal processing techniques for compensating for distortion introduced within the waveguide 300 are described later.

[0052] Although depicted as separate elements, the SBGs 300-1, 300-2 may actually be separate, independently controllable regions of a single large SBG that extends over all or a majority of the first side surface 300-S1.

[0053] SBGs are just one possible form of active switching element. For example, for polarized beams, a controllable polarization filter attached to the surface of waveguide 300 or embedded in the body of the waveguide can be used to achieve the same effect. SBGs and controllable polarization filters are examples of non-mechanical active switches that can change the optical properties of waveguide 300 through non-mechanical effects. Other examples of guiding elements are controllable mirrors including micromirror devices or other micro-electromechanical systems (MEMs), which are examples of mechanical guiding elements.

[0054] When using polarizing filters as steering elements, SBGs 300-1, 300-2 may be replaced with passive diffractive elements, with the polarizing filters being used to controllably steer the light beams into and out of the passive diffractive elements as desired without reconfiguring the diffractive elements.

[0055] Note that even if the guiding element itself is mechanical, this still does not require overall mechanical movement of the waveguide 300.

[0056] Active Light Pipe Network

[0057] Here, a "waveguide network" can take the form of a single waveguide or a network of multiple mutually coupled waveguides. Waveguide networks with multiple active light guides have particular advantages in flexible optical data transmission.

[0058] Figure 4A and Figure 4BAlternating side views of a waveguide network (portion) including first and second active light pipes 400, 420 are shown. The second light pipe 420 has a first surface area 420-0, which is positioned adjacent to and aligned with a corresponding surface area of ​​the first light pipe 400 for receiving a light beam from or directing a light beam toward the second waveguide 420 via the first surface area 400-0. By way of example only, a light ray 404 is shown as propagating through the first waveguide 400 to a corresponding surface area of ​​the first waveguide 400 adjacent to the first surface area 420-0 of the second waveguide 420. The light ray 404 is coupled out of the first waveguide 400 via an SBG 400-1 attached to an adjacent surface area of ​​the first waveguide 400, and enters the second waveguide 420 via the first surface area 400-0. From there, it can be directed toward any one of a plurality of SBGs 420-1, 420-2 of the second waveguide 420 in a one-to-many manner. The same arrangement can be used to direct light beams in the other direction from the second waveguide 420 to the first waveguide 400 in a many-to-one manner, with the direction of the light beams being opposite.

[0059] Although this example considers two mutually coupled waveguides 400, 402, the principles can be applied to a greater number of mutually coupled waveguides to allow flexible data routing through the waveguide network.

[0060] More generally, a surface region of the medium may be optically coupled to a corresponding surface region of the waveguide in some other manner, such as via an air interface or one or more other optical components (which may themselves be waveguides and may or may not provide active or passive switching functionality).

[0061] Holographic storage

[0062] The use of active light guides in holographic storage will now be described.

[0063] Figure 1A and 1BA schematic perspective view of a holographic recording medium 102 is shown, which is a relatively thick volume of photosensitive material capable of durably storing an optical pattern as a "hologram" embodied in the holographic recording medium 102 (which, for brevity, may be referred to simply as the medium 102). The hologram is created by exposing a subvolume 110 (region) of the medium 102 to an optical pattern that causes a persistent state change within the subvolume 110. The hologram created using the subvolume 110 through the state change records the optical pattern into the medium 102 so that the optical pattern can be subsequently reproduced therefrom. The hologram is persistent in that once created, the medium 102 does not require power to maintain it. The composition and structure of the medium 102 may be such that a hologram cannot be erased once created, thus providing a "write once read many times" (WORM) form of storage, or may be such that the hologram can be erased and replaced (but still exists unless and until it is erased).

[0064] A single hologram can record an optical pattern that encodes a very large number (e.g., millions) of bits, allowing large amounts of data to be written / read in parallel (simultaneously) to / from the holographic recording medium 102. Another benefit of holographic storage is that many holograms can be written to the same subvolume 110 of the holographic recording medium 102, which greatly increases the data storage capacity of the holographic recording medium 102 per unit volume.

[0065] More specifically, Figure 1A It is shown how, in order to write a set of data to the medium 102, an input beam 104 and a reference beam 106 are directed into the sub-volume 110 through the first side surface 102-4 and the second side surface 102-6 of the medium 102, respectively. This produces an optical pattern in the form of an interference pattern caused by the interference between the input beam 104 and the reference beam 106. Assuming that the beams 104, 106 have sufficient power and the sub-volume 110 is exposed for a sufficient duration, the interference pattern produced by the interfering beams 104, 106 will be durably recorded in the sub-volume 110 as a hologram. A set of data is embedded in the input beam 104 and can be recovered from the resulting hologram, which will be discussed below. In this way, an encoded data set is written to the sub-volume 110. In the following example, the data set is encoded as a digital image and then embedded in the input beam 104 via spatial modulation.

[0066] like Figure 1BAs shown, to read data from the sub-volume 110, a matching reference beam 116 is directed into the sub-volume 110 through the second side surface 102-6 of the medium 102, where it interacts with the hologram to create an output beam 108 that will substantially match the input beam 104 used to write the hologram, whereby the embedded data can be recovered from the output beam 110. The output beam 108 propagates out of the sub-volume 110 via the third side surface 102-8 of the medium 102.

[0067] The reference beam 116 used to read the data substantially matches the reference beam 106 originally used to write the data, and in particular, the reference beam 116 is directed at an angle (or more generally, a direction) that closely matches the angle of the original reference beam 106. This is because the ability to read a hologram (i.e., to produce an output beam 108 from which data can be recovered) is highly sensitive to angular deviations between the reference beams 106, 116 used to write and read the hologram, respectively. It is this sensitivity that can be used to record multiple holograms within the same subvolume 110 - each hologram is created using a different reference beam angle, and only a slight difference in the reference beam angles can create two different holograms. In this way, a large number (e.g., hundreds or thousands) of holograms can be written to the same subvolume 110, each hologram encoding a large number (e.g., millions) of bits.

[0068] Figure 2AA schematic perspective view of an example holographic storage system 200 incorporating certain principles of the present disclosure is shown. In this particular example, three separate waveguides 204, 206, and 208 are used to carry the input beam 104, the reference beams 116, 126, and the output beam 118, and may be referred to as the input waveguide 204, the reference waveguide 206, and the output waveguide 208, respectively. As noted above, the terms "optical waveguide" and "light pipe" are used interchangeably herein. Each of the waveguides 204, 206, and 208 may provide spatial multiplexing in that it may direct a signal to any one of a plurality of sub-volumes within the holographic recording medium 102 (in the case of the input and reference waveguides 204, 206), or direct a signal from any one of a plurality of sub-volumes within the holographic recording medium 102 (in the case of the output waveguide 208). This provides spatial multiplexing across the volume of the holographic recording medium 102 without requiring any mechanical movement of any of the waveguides 204, 206, 208 relative to the holographic recording medium 102. To avoid the need for such mechanical motion, a guiding element is located on or within each waveguide 204, 206, 208 and is configurable to change the optical properties of the waveguide 204, 206, 208 so as to guide signals to or from different sub-volumes of the medium 102. That is, different channels are created as desired within the waveguide 204, 206, 208. In this particular example, the guiding element takes the form of an active optical switching element (switch). The switch can take a variety of forms. In this example, the switch takes the form of an SBG located in different surface areas of the waveguide 204, 206, 208, with the overall arrangement as shown. Figure 3A-3E That is, the waveguides 204, 206 and 208 are all in the form of active light pipes, and each of the waveguides 204, 206, 208 has Figure 3A-3E The active light pipe 300 has the same general physical structure as the active light pipe 300.

[0069] Each of the waveguides 204, 206, 208 is arranged so that its first surface (i.e., the surface on which its SBG is located) is adjacent to a different side surface of the medium 102, so that its SBG extends along the side surface of the medium 102. The first SBG and the second SBG of each waveguide 204, 206, 208 are represented by reference numerals 204-1, 204-2; 206-1, 206-2; and 208-1, 208-2, which can all be configured in the manner described above. The description of the other SBGs does not use reference numerals, and the number of SBGs can be selected to accommodate any size of the holographic recording medium 102. For the sake of brevity, the following description will refer to the first SBG and the second SBG of each waveguide 204, 206, 208, but it will be understood that the description applies to a greater number of SBGs.

[0070] Figure 2B to Figure 2DIt is shown how the input and reference waveguides 204, 206 are used to write data to the medium 102 in a one-to-many manner. Figure 2B shows a schematic plan view of a system 200, Figure 2C and Figure 2D An alternate side view is shown, in which the input and reference waveguides 204, 206 are respectively visible. The input waveguide 404 is used to direct the input beam 104 to any of a plurality of sub-volumes of the medium 102 via any of the SBGs 404-1, 404-2 of the input waveguide 204 in the manner described above. The reference waveguide 406 is configured to direct the reference beam 106 simultaneously to the same sub-volume in order to create a desired interference pattern to be written to the sub-volume. In the depicted example, both the input and reference waveguides 204, 206 are currently configured to direct the input and reference beams 104, 106 to the sub-volume indicated by reference numeral 110 via the second SBG 204-2, 206-2 of each waveguide 204, 206.

[0071] Figure 2E to Figure 2G It is shown how the reference and output waveguides 206 , 208 are used to read data from the medium 102 . Figure 2E It is a floor plan. Figure 2F and 2G An alternate side view is shown in which the reference and output waveguides 204, 206 are visible. The reference waveguide 206 is used in the same manner as FIG. 2B to FIG. 2D , but here it is used to direct the reference beam 116 toward whichever daughter the hologram is to be read from - in this case, daughter 110. The output waveguide 208 is used to direct the resulting output beam 108 from daughter 110 in a one-to-many manner and through the through waveguide 208 for subsequent detection.

[0072] Each sub-volume 110 may, for example, have a height and width of a few millimeters measured along any side surface, and this is typically sufficient to store millions of pixels (e.g., multiplexing angles) per data "page" - where in this case the volume of the sub-volume is sufficient to store (million pixels)*(#multiplexing angles).

[0073] The guiding elements (SBGs in this example) of the input waveguide 204 and reference waveguide 206 are configured as required to provide a path for the input beam 104 and reference beams 106, 116 to go from the beam source (transmitting system) to the sub-volume 108 to be read. For SBGs, this is a case of setting the SBGs to a transmissive or reflective state as required to create the path. Similarly, the guiding elements of the output waveguide 208 (also SBGs in this example) are similarly set to provide a path from the sub-volume 108 to be read to the detector. To provide more context, this will be referred to below Figure 5The multi-waveguide network depicted in is described in more detail. However, Ref. Figure 5 The principles described with respect to the specific example are generally applicable to other waveguide network topologies, whether simpler networks (e.g., a single waveguide) or more complex waveguide networks.

[0074] As described above, this allows spatial multiplexing on the medium 102 without requiring any mechanical movement of the medium 102 relative to the waveguides 204, 206, 208. This is true regardless of the form the guiding elements take (the guiding elements themselves may be mechanical or non-mechanical, as described above).

[0075] Holographic storage using multi-waveguide networks

[0076] Figure 5 An example of a holographic storage system incorporating a multi-waveguide network of the type shown in FIG. 4 is shown.

[0077] The input waveguide network is shown to include a first input light pipe 203 ("father" waveguide) to which a plurality of second input light pipes 204A, 204B ("daughter" waveguides) are coupled. An input light beam 104 from a transmitter system 504 is coupled into the first input waveguide 203 via its incoupling region and may be directed from there into any of the second input waveguides 204A, 204B.

[0078] The reference waveguide network is shown to include a first reference waveguide 205 to which a plurality of second reference waveguides 206A, 206B are coupled. Reference beams 106, 116 from the transmitter system 504 are similarly coupled into the first reference waveguide 205 and may be directed toward any of the second reference waveguides 206A, 206B.

[0079] The output waveguide network is shown to include a first output waveguide 207 to which a plurality of second output waveguides 208A, 208B are coupled.

[0080] The depicted arrangement allows for directing light beams to / from different subsets of multiple pieces of holographic storage media 102A, 102B.

[0081] Although FIG. 4 shows an input beam 104, reference beams 106, 116, and an output beam 108, it should be understood that the sub-body will typically be referenced at different times. Figure 2A-2G Describes the way it is written and read.

[0082] A first set of second waveguides 204A, 204B, 204C (each of the input, reference and output) is located around the first block of holographic storage medium 102A (first medium), and a second set of second waveguides 204B, 206B, 208B is located around the second block 102B (second medium), each having a Figure 2A-2G Thus, the input and reference beams 104, 106, 116 can be directed to any subvolume of each block of dielectric 102A, 102B by first directing the beams to the desired second waveguide of the input and reference networks, respectively, and then to the desired subvolume of the dielectric block adjacent to the desired waveguide.

[0083] The output waveguide network can be used to guide the output beam 108 from any sub-volume of any dielectric block 102A, 102B from the applicable second output waveguide 208A, 208B into the first output waveguide 207 and from there to the detector 508 via the outcoupling region of the first output waveguide 207. In order to read from a particular sub-volume, the SBGs are configured to provide a path from that sub-volume to the detector; thus, in this case, SBGs 204A-2 and 207A-1 are set to a transmissive state, and other SBGs of the output waveguide network are set to a reflective state as needed to provide a path for the output beam 108 to go to the detector 508 (e.g., in this case, SBG 207-2 of the first output waveguide 207 is set to a reflective state to prevent the output beam 104 from propagating into waveguide 207-2). Other SBGs of the output waveguide network may be set to reflective as needed to prevent transmission of any unwanted light, i.e., "leakage" from other areas of the same block of media 102A or from a different block of media 102B (e.g., in this example, SBG 204A-1 near the subvolume being read is shown as being set to reflective to prevent unwanted leakage).

[0084] Although in the above examples, three separate waveguide networks are used for the input, reference, and output beams 104, 106, 116, 108, this is not required. For example, the same waveguide network may be used to carry the input beam 104 and the reference beams 106, 116, and / or the same waveguide network may be used to carry the input beam 104 and the output beam 108, and / or the same waveguide network may be used to carry the output beam 108 and the input beam 104. In general, it is expected that having three separate networks will provide optimized performance, but implementations using only one or two waveguide networks are certainly feasible.

[0085] Although not depicted in any figure, a fourth waveguide network may be used to deliver beams to the remaining side surfaces of the dielectric blocks 108A, 108B. For example, the fourth network may be used to deliver an erasing beam to a desired subvolume, suitable for erasing at least a hologram therefrom (in the case of erasable holographic storage).

[0086] Fig. 9 An alternative physical configuration is shown in which a single "slab" of holographic medium 102 is used instead of Figure 5 An input waveguide network is depicted, which has substantially the same physical configuration, but the second input waveguides 204A, 204B are now configured to direct the input light beam 104 to different sub-volumes of the same plate 102. Figure 5 In the embodiment, each second input waveguide 204A, 204B provides multiplexing in a single dimension along the length of a different monolithic medium 102A, 102B. Fig. 9 , the second waveguides 204A, 204B provide spatial multiplexing in two dimensions on the slab of holographic medium 102 (each waveguide individually provides one-dimensional multiplexing, but there is 2D multiplexing on the slab 102 as a whole).

[0087] Fig. 9 The system is limited to a maximum of two waveguide networks (one on each side of the board 102). As mentioned above, this is still a viable arrangement because the same network can be used to carry multiple beams.

[0088] Data Encoding

[0089] Fig. 6A An example of an emitter system 504 is shown that provides both an input beam 104 and a reference beam 106. The input beam is an expanded, spatially modulated laser beam. A laser 600 emits a coherent, narrow laser beam, which is split using a beam splitter 604.

[0090] A portion of the beam from the beam splitter 602 is used as the reference beam 106. In this example, a controllable reference beam steering element 612 is used to steer the reference beam 106 at a desired angle to the reference waveguide 106. By changing the angle of the reference beam 106 before it is coupled to the reference waveguide 206, different holograms can be written to / read from the same subvolume of the medium in the manner described above.

[0091] Instead of beam angle multiplexing or as a complement, multiple patterns can be stored to and read from the same subvolume using different phases of the reference beams 106, 116 (phase multiplexing). Thus, a logical address can correspond to a specific reference beam angle and / or phase characteristic. All descriptions of reference beam angle modulation apply equally to phase modulation.

[0092] The other part of the beam from the beam splitter 602 is expanded using a beam expander 604, and the expanded beam passes through a spatial light modulator (SLM) 606. An encoder 610 receives the data set to be encoded and encodes it into a digital image, which is then modulated into the expanded beam via the SLM 606. Incoupling optics are used to separate the expanded beam into different propagation modes, in this case the incoupling optics is a Fourier lens 608, which is positioned so that the plane of the SLM 606 is substantially located in the focal plane of the Fourier lens 608; a mode corresponds to a unique propagation direction in this case, and each mode now corresponds to a specific point in the plane of the SLM 606. The different propagation modes are coupled into the input waveguide 202, through which they are guided in the manner described above. Using the incoupling optics 608, the data is "angle encoded" within the reference beam, that is, a point within the digital image substantially corresponds to a unique propagation direction, that is, a unique propagation mode of the input beam 104. This is similar to light rays from a distant object being considered to be infinitely far away. Fig. 6A The angle-encoded input beam 104 is an example of a "multimode" optical signal with multiple propagation modes (ie, components propagating in different directions), and this arrangement provides a form of angular diversity.

[0093] Note that the term "multimode" does not necessarily imply the use of such an incoupling optic 608, nor does it require that each image point uniquely correspond to a given propagation direction. That is, multimode does not necessarily imply a one-to-one correspondence between propagation modes and image points / data points. For example, Figure 6B Another possible transmitter system is shown in which a spatially modulated beam is coupled directly to the input waveguide 204. In this case, there are still multiple modes (i.e., multiple spatial paths through the waveguide for any given channel), but there is no one-to-one correspondence between propagation directions and image points, nor may there be any one-to-one correspondence between image / data points and modes. This provides a form of spatial diversity based on a MIMO (multiple input multiple output) form of transmission through the multiple pixels of the SLM 606 and the detector array of the spatially coherent detector 508.

[0094] Data decoding

[0095] Figure 7A spatial coherence detector 508 is shown for measuring the light field of the output beam 108. In contrast to conventional "direct detection", the spatial coherence detector 508 comprises an array of pixels (or more generally, detector elements), each configured to measure the amplitude and phase (rather than just the intensity) of the light field at that pixel location. These can be measured, for example, using a local oscillator 712 of the spatial coherence detector 508. The pixel array is thus able to measure changes in the phase and amplitude of the light field in time and space, and thus provide an analog or digital representation of the measured light field. In this example, the measured light field is the light field of the output beam 108 guided to the spatial coherence detector 208 by the output waveguide 208.

[0096] Although only a single array is depicted, there may actually be multiple physical arrays cooperating as a single "logical array." For example, this logical array may be split across two physical phases.

[0097] The physical detector array can take the form of a single camera (each detector element is a pixel or group of pixels of the camera) or multiple cameras. In the extreme case, each detector element may be a separate camera, in which case the logical detector array may be split into a very large number of physical detectors.

[0098] As noted, the path from a particular incoupling region where a beam enters a waveguide network to a particular outcoupling region where it leaves the waveguide network (these regions may be in the same or different waveguides) may be referred to herein as a "channel". As previously noted, in a multimode waveguide network, a single channel will contain multiple spatial paths. The output beam 108 will have been directed via a particular channel of the output waveguide network, i.e., from its particular incoupling region to the outcoupling region of the output waveguide 208. In addition, it will have been generated from a hologram that was created using an input beam that was directed from the incoupling region of the input waveguide network to its particular outcoupling region. The hologram will have been created and read using a reference beam that was similarly directed through the reference waveguide network via a particular channel. The input beam 104, the reference beams 106, 116, and the output beam 108 are all susceptible to distortions within the associated waveguide network that are specific to the channel through which these beams are directed. The signal processing component 700 applies analog and / or digital signal processing to the representation of the measured field to compensate for this distortion; it does this using the channel model associated with the subvolume currently being read from (i.e., the subvolume that produced the output beam 108). The channel model associated with a particular subvolume models not only the channel through which the output beam 108 is directed to the detector 508, but also the channel through which the input beam 104 used to write a hologram is directed to that subvolume, and the channel through which the reference beams 106, 116 used to write / read a hologram are directed to that subvolume.

[0099] Each channel model may, for example, take the form of a transfer function (modeling the channel directly) or an inverse transfer function (modeling the channel according to its approximate inverse). Note that the transfer function applies to a representation of the measured light field, i.e., its phase and amplitude measured at different points in space, rather than just the intensity of the light. Spatially coherent detection provides greater scope for eliminating or reducing such channel distortions, with the goal of restoring the original digital image accurately enough to support the decoder 704 in decoding the encoded data in the restored image.

[0100] Signal processing 700 may, for example, use a combination of optical and computational techniques to correct for phase interference and noise, which techniques may, for example, include machine learning techniques.

[0101] Although described in the context of holographic storage, the use of this signal processing 700 in combination with spatially coherent detection is not limited in this regard and may be applied in other contexts, such as optical communications or optical computing, or any other context in which the received output beam is susceptible to distortions introduced in one or more waveguide networks.

[0102] Figure 7 The outcoupling optics 715 are shown, which are arranged to substantially invert Figure 6B The effect of the incoupling optics 608 is to resolve each propagating mode into essentially a single point in the plane of the spatial coherence detector 508. Again, this is not required and the use of Figure 6B In an alternative transmission system, the outcoupling optics 715 may be omitted.

[0103] Although not in Fig. 6A 6B, but some degree of pre-processing may be applied to the digital image before it is modulated into the input beam 104. This may reduce the degree of compensation required on the detector side. Even with such pre-processing, some amount of detector side processing may be applied to account for different distortion effects between different channels.

[0104] Dynamic Scheduling

[0105] Figure 8 A controller is shown in the form of a scheduler 800 that can schedule read and write operations within a holographic storage system of the type described above. To support efficient scheduling, each subvolume within the medium 108 or each subvolume within each piece of media 108A, 108B is assigned a unique address. This provides a form of addressable holographic storage similar to more traditional addressable electronic storage forms. However, there are many differences compared to traditional addressing.

[0106] First, as described above, a single subvolume can store holograms for multiple different reference beam angles. To accommodate this, each address uniquely corresponds to a specific subvolume in conjunction with a specific reference beam direction, i.e., each available tuple is assigned a unique address representing a specific subvolume within one of the media 102A, 102B of the medium 102, and representing a specific reference beam direction (e.g., an angle or a set of multiple angles defining the beam direction; the term "angle" may be used as a shorthand for referring to the direction of the reference beam, although it will be appreciated that the direction may actually be defined by multiple angles depending on the configuration of the system). Thus, a subvolume may be associated with a potentially large number of addresses, corresponding to different reference beam angles. A tuple defines a logical storage location, where multiple logical storage locations are provided at a physical level by the same subvolume at different reference beam angles. Each logical storage location has a unique address (ADDR). This notation is used as a shorthand for representing an address corresponding to a subvolume and a reference beam angle, although it should be understood that this does not imply any particular representation of an address. Any address space and addressing mechanism that uniquely identifies a logical storage location of this nature may be used.

[0107] Second, unlike traditional storage, each logical storage location can store an entire image, so a single logical storage location can potentially store a large number (e.g., thousands or millions) of bits.

[0108] The scheduler 800 operates at a logical storage level and schedules incoming read and write operations associated with different addresses within appropriate time periods.

[0109] Reference numerals 804, 806 and 808 are used to represent input, reference and output optical waveguide networks, respectively. As described above, each is a single waveguide network or a multi-waveguide network (e.g., Figure 5 ), having one or more configurable guiding elements (e.g., SBGs or other active switching elements) that can be used to create channels to different sub-volumes of a piece (or multiple pieces) of holographic storage media.

[0110] During a period (write period) in which a write operation associated with a particular address is scheduled, the guiding elements within the input and reference waveguide networks 804, 806 are arranged to create a passage for the input beam 104 and the reference beam 106 from the emitter system 504 to the respective daughter through the input and reference networks 804, 806, respectively; and the reference beam steering element 612 is arranged to direct the reference beam 106 in a respective direction into the reference network 806. This results in the creation of a desired interference pattern within the daughter at the reference beam angle, which in turn results in the interference pattern being durably stored as a hologram, provided that the daughter is exposed to the interference pattern for a sufficiently long duration.

[0111] During the period (write period) when a read operation related to a specific address is scheduled, the guiding elements within the reference and output networks 806, 808 are similarly arranged to: create a channel for the reference beam 116 to go to the daughter through the reference network 806, and create a channel for the output beam 108 from the daughter to the detector 508 through the output network 808; the reference beam steering element 612 is similarly arranged to guide the reference beam 116 in the corresponding direction into the reference network 806 so as to read the expected hologram at the daughter and reference beam angles. Alternative waveguide network:

[0112] Fig. 10A and 10B An alternative system is shown in which spatial multiplexing is achieved by modulating one or more optical properties of the input and reference beams 104, 106, 116. In such a system, passive (non-switchable) steering elements may be used in place of the active (switchable) steering elements of the previous figures.

[0113] Fig. 10A An example of frequency (or equivalently, wavelength) modulation is considered. In this case, the light pipes themselves (they themselves) can be passive, with static wavelength-dependent output coupling (such as continuously longer pass dichroic interference filters, or varying center wavelength bandpass filters).

[0114] Fig.11A 1 and 2. A light pipe 1100 is shown having an outer surface 1100-S along which a plurality of passive filters 1100-1, 1100-2 are placed. The configuration of the light pipe 1100 is similar to that of the SBG 300-1, 300-2, except for the fact that the filters 1100-1, 1100-2 replace the SBG 300-1, 300-2. Figure 3A-3D The filters 1100-1, 1100-2 have different frequency responses (ie, they act as frequency filters). More specifically, each filter 1100-1, 1100-2 is substantially transmissive for a relatively narrow range of optical frequencies, and substantially reflective for frequencies outside of this range. Fig.11A An incoupled beam 1104 is shown, whose frequency is within the range of the second filter 1100-2, but outside the range of the first filter 1100-1. Thus, the beam 1104 reflects from the former, but is transmitted through the latter (thus exiting the light pipe 1100 at this location). Fig. 11B A light beam 1104' is shown having a different frequency, which is now within the range of the first filter 1100-1, and is therefore transmitted through the first filter 1100-1.

[0115] Such a light pipe 1100 may be used to replace the active light pipe described above, and the above description is equally applicable to the following modifications of the system.

[0116] Fig. 10A A scheduler 800 is shown that is communicatively coupled to the laser 600 of the transmitter system for varying the frequency (or equivalently, wavelength) of the input and reference beams 104, 106, 116. In this case, either beam can be directed toward a desired holographic storage area by setting the frequency accordingly. The different beam frequencies now correspond to different paths through the waveguide network (defined by the different frequency characteristics of the passive filters), and the frequencies can be set to correspond to any desired path.

[0117] In this case, wavelength is used as the switching dimension.Laser 600 is a rapidly tunable laser that acts as an active element.

[0118] In such an implementation, switching can be in only one spatial dimension (i.e. along a single conduit). However, using a laser with sufficient range and line narrowness, the first light guide can filter coarsely (i.e. over a relatively wide wavelength range) and subsequent light guides can sample more finely (i.e. over a narrower wavelength range). Another factor limiting the lines is the need for relatively long coherence lengths, so the lines are likely to be narrow enough in any case. To implement replication of an input field across 2D output controls to addressable locations in a holographic storage context, this implementation can, for example, be combined with a second implementation using a different switchable parameter (e.g. polarization).

[0119] In the context of a read operation, the frequency of the output beam 108 will be matched to the frequency of the reference beam 116 used to read the particular subvolume, and can be directed back to the detector using appropriate filters in the output waveguide network 808, applying the same principles.

[0120] Fig. 10B An example of such an implementation is shown with a controllable polarization element 601, which can be used to change the polarization of the input and reference beams 104, 106, 116. This can be combined with a passive polarization filter on or within the light pipe. This can be implemented as Fig. 10A This polarization modulation will provide two independent paths and can be effectively combined, for example with passive wavelength filtering and / or active light pipes. Polarization modulation of the light beam can also be combined with active polarization filters.

[0121] Note that all of the various "passive" and "active" implementations described above can be implemented individually or in combination, e.g. a combination of active and passive guiding elements can be used. That is, a waveguide can have both passive and active elements and / or active and passive waveguides can be combined in the same network.

[0122] Other hierarchy levels:

[0123] The above examples consider a waveguide network with two hierarchical "levels" of parent-child waveguides. However, a multi-waveguide network may have three levels (parent, child, grandchild) or more. Note that the terms "child", "parent" and "grandchild" do not necessarily imply a direct hierarchical relationship, i.e., the term child or grandchild may refer to any waveguide at any hierarchical level below the parent or child waveguide, respectively; that is, a child / grandchild waveguide may be optically coupled to a parent / child waveguide not only through, for example, an air interface (direct descendant), but also through one or more of its other child / grandchild waveguides (indirect descendants).

[0124] Fig.12 An example of a waveguide network having a three-level hierarchy is shown. A parent waveguide 1200 has two direct daughter waveguide networks 1202A, 1202B optically coupled to it in the manner described above, and each of these daughter waveguides 1202A / 1202B has two grandchild networks 1204A-A, 1204A-B / 1204B-A, 1204B-B optically coupled to it in the same manner.

[0125] An extreme example is a "binary tree" architecture, where each waveguide has exactly two direct children, with the possibility of more than three levels of waveguides. In practice, however, there may be cases where it is preferable to increase the number of direct children to reduce the number of levels required.

[0126] Figure 8 , Fig. 10A and Fig. 10B The scheduler 800 shown in is a functional component of the system. Similarly, encoder 610, decoder 704 and signal processing component 700 are functional components. Such components can be implemented in software (i.e. as program code executed on one or more programmable hardware processors, such as CPU, accelerator, such as GPU, etc.), or use other forms of processor hardware, such as field programmable gate array and / or application-specific integrated circuit. The signal processing performed by signal processing component 700 can be analog or digital signal processing, or any combination thereof. Such program code and other data (such as channel model 702) can be encoded in computer-readable storage. Examples of computer-readable storage include optical, magnetic and / or solid-state storage, in which code, data, etc. can be stored in non-temporary form. This contrasts with transient media such as transient signal carriers.

[0127] A first aspect of the present invention provides a multimode optical waveguide network, comprising: a parent waveguide; and a plurality of daughter waveguides; wherein each of the parent and daughter waveguides is a multimode optical waveguide having a first surface area, a plurality of second surface areas, and at least one guiding element attached to a waveguide surface or embedded in the waveguide, each of the second surface areas of the parent waveguide being optically coupled to the first surface area of ​​a corresponding one of the daughter waveguides; and wherein the at least one guiding element of the parent waveguide is arranged to guide a light beam from its first surface area to any selected second surface area of ​​its plurality of second surface areas or to guide a light beam from any selected second surface area of ​​its plurality of second surface areas to its first surface area, the light beam passing through the first surface area of ​​the parent waveguide The second surface area and the first surface area of ​​the corresponding sub-waveguide are coupled into or received from the corresponding sub-waveguide, the first surface area of ​​the corresponding sub-waveguide is optically coupled to the second surface area of ​​the parent waveguide, and the at least one guiding element of each sub-waveguide is arranged to guide the light beam from its first surface area to any selected second surface area among its multiple second surface areas or to guide the light beam from any selected second surface area among its multiple second surface areas to its first surface area, wherein the at least one guiding element of each of the waveguides can be configured to select the second surface area of ​​the waveguide and / or select the second surface area of ​​the waveguide via modulation of the at least one light beam characteristic in response to at least one light beam characteristic.

[0128] In an embodiment, a multimode optical waveguide network may include multiple sub-waveguides, each of which is a multimode optical waveguide having a first surface area, multiple second surface areas, and at least one guiding element attached to the surface of the sub-waveguide or embedded in the sub-waveguide, each of the second surface areas of each sub-waveguide being optically coupled to the first surface area of ​​a corresponding sub-waveguide among the sub-waveguides; wherein the at least one guiding element of each sub-waveguide is arranged to guide a light beam from its first surface area to any selected second surface area of ​​its multiple second surface areas or to guide a light beam from any selected second surface area of ​​its multiple second surface areas to its first surface area, the light beam being coupled into or out of the sub-waveguide via the first surface area of ​​the sub-waveguide and the second surface area of ​​the sub-waveguide optically coupled to the first surface area of ​​the sub-waveguide, and the at least one guiding element of each of the sub-waveguides may be configured to select the second surface area of ​​the sub-waveguide and / or select the second surface area of ​​the sub-waveguide via modulation of the at least one light beam characteristic in response to at least one light beam characteristic.

[0129] Each of the waveguides has at least one active guiding element configurable for selecting the second surface area of ​​the waveguide.

[0130] Each of the waveguides has at least one guiding element that is responsive to at least one beam characteristic for selecting the second surface area of ​​the waveguide via modulation of the at least one beam characteristic.

[0131] At least one of the waveguides has at least one active guiding element configurable for selecting the second surface area of ​​the waveguide, and at least another of the waveguides has at least one guiding element for selecting the second surface area of ​​the another waveguide via modulation of the at least one beam characteristic in response to an element of the at least one beam characteristic.

[0132] One of the parent waveguides and one of the child waveguides has at least one wavelength-responsive guiding element, so that a light beam in a first wavelength range is guided from its first surface area to a first child waveguide or grandchild waveguide in the child waveguide or grandchild waveguide, or from a first child waveguide or grandchild waveguide in the child waveguide or grandchild waveguide to its first surface area, and a light beam in a second wavelength range is guided from its first surface area to a second child waveguide or grandchild waveguide in the child waveguide or grandchild waveguide, or from a second child waveguide or grandchild waveguide in the child waveguide or grandchild waveguide to its first surface area; wherein the first child waveguide or grandchild waveguide has at least one wavelength-responsive guiding element, so that a light beam in a first sub-range of the first wavelength range is guided from its first surface area to one of its second surface areas, or from the one of its second surface areas. Toward its first surface area, the light beam within the second sub-range of the first wavelength range is guided from its first surface area to another second surface area in its second surface area or from the another second surface area in its second surface area to its first surface area; and wherein the second sub-waveguide or grand-waveguide has at least one wavelength-responsive guiding element, so that the light beam within the first sub-range of the second wavelength range is guided from its first surface area to one second surface area in its second surface area or from the one second surface area in its second surface area to its first surface area, and the light beam within the second sub-range of the second wavelength range is guided from its first surface area to another second surface area in its second surface area or from the another second surface area in its second surface area to its first surface area.

[0133] The or each active guiding element has at least one of: a configurable transmittance or reflectivity, or a configurable refractive index.

[0134] The or each active steering element is a switchable grating or grating region.

[0135] At least one of the guiding elements is a wavelength and / or polarization filter having a fixed or configurable wavelength response and / or a fixed or configurable polarization axis.

[0136] At least one of the waveguides has two or more guiding elements and three or more second surface areas, any one of which can be selected by configuring one or both of the two or more guiding elements and / or modulating at least one beam characteristic.

[0137] A second aspect of the present invention provides an optical system, comprising: a first optical system component; a plurality of second optical system components; at least one multimode optical waveguide network according to any of the above aspects or embodiments, the multimode optical waveguide network being arranged to guide a light beam from the first optical system component to any selected second optical system component among the plurality of second optical system components, or to guide a light beam from any selected second optical system component among the plurality of second optical system components to the first optical system component; a controller configured to select a second optical system component among the plurality of second optical system components, and to guide a light beam from the first optical system component to the selected second optical system component, or to guide a light beam from the selected second optical system component to the first optical system component by configuring at least one of the guiding elements of the multimode optical waveguide network and / or modulating at least one beam characteristic.

[0138] The first system component may include an emitter system from which a light beam is emitted and directed toward a selected one of the second system components, or a detector array to which a light beam is directed from a selected one of the second system components.

[0139] The optical system may include one or more holographic recording media, wherein at least some of the second system optical components may be respective sub-volumes of the one or more holographic recording media.

[0140] The optical system may include a second multimode optical waveguide network according to any of the above aspects or embodiments, and the controller may be configured to cause a second optical beam to be directed from the first optical system component to the same selected second optical system component, or cause a second optical beam to be directed from the same selected second optical system component to the first optical system component, by configuring at least one of the guiding elements of the second multimode optical waveguide network and / or modulating at least one beam characteristic.

[0141] The optical system may include a third multimode optical waveguide network according to any of the above aspects or embodiments, and the controller may be configured to cause a third optical beam to be directed from the first optical system component to the same selected second optical system component, or cause a third optical beam to be directed from the same selected second optical system component to the first optical system component, by configuring at least one of the guiding elements of the third multimode optical waveguide network and / or modulating at least one beam characteristic.

[0142] In the context of optical communications or optical computing, for example, at least one of the first and / or second optical system components may include a signal converter configured to convert an optical beam into an electrical signal or to convert an electrical signal into an optical beam, or an optical processor.

[0143] It should be understood that the above embodiments are described by way of example only. Other variations or use cases of the disclosed technology may become apparent to those skilled in the art once the disclosure herein is given. The scope of the present disclosure is not limited by the described embodiments, but only by the appended claims.

Claims

1. A multimode optical waveguide network, comprising: parent waveguide; as well as a first sub-waveguide and a second sub-waveguide; wherein each of the parent waveguide and the first and second sub-waveguides is a multimode optical waveguide having a first surface area, at least two second surface areas, and at least one guiding element, wherein at least one of the second surface areas of the parent waveguide is optically coupled to the first surface area of ​​the first sub-waveguide, and wherein at least another of the second surface areas of the parent waveguide is optically coupled to the first surface area of ​​the second sub-waveguide; as well as wherein the at least one guiding element of the parent waveguide is arranged to guide a light beam from the first surface area of ​​the parent waveguide to any selected second surface area of ​​the at least two second surface areas of the parent waveguide or to guide a light beam from any selected second surface area of ​​the at least two second surface areas of the parent waveguide to the first surface area of ​​the parent waveguide, the light beam is coupled into or received from the corresponding first sub-waveguide or second sub-waveguide via the selected second surface area of ​​the parent waveguide and the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide, the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide is optically coupled to the selected second surface area of ​​the parent waveguide, the at least one guiding element of each of the first sub-waveguide and the second sub-waveguide being optically coupled to the selected second surface area of ​​the parent waveguide, A guiding element is arranged to guide a light beam from the first surface area of ​​the corresponding first sub-waveguide or the second sub-waveguide to any selected second surface area of ​​the at least two second surface areas of the corresponding first sub-waveguide or the second sub-waveguide, or to guide a light beam from any selected second surface area of ​​the at least two second surface areas of the corresponding first sub-waveguide or the second sub-waveguide to the first surface area of ​​the corresponding first sub-waveguide or the second sub-waveguide, wherein the at least one guiding element of each of the parent waveguide, the first sub-waveguide and the second sub-waveguide can be configured to switch the guiding of the light beam between the at least two second surface areas of the waveguide by at least one of changing the optical property of the at least one guiding element and modulating at least one light beam characteristic.

2. The multimode optical waveguide network of claim 1, comprising a first sub-waveguide and a second sub-waveguide, wherein each of the first sub-waveguide and the second sub-waveguide is a multimode optical waveguide having a first surface area, at least two second surface areas, and at least one guiding element, wherein at least one second surface area of ​​the first sub-waveguide is optically coupled to the first surface area of ​​the first sub-waveguide, and wherein at least one second surface area of ​​the second sub-waveguide is optically coupled to the first surface area of ​​the second sub-waveguide; The at least one guiding element of each of the first and second sub-waveguides is arranged to guide a light beam from the first surface area of ​​the corresponding first or second sub-waveguide to any selected second surface area of ​​the at least two second surface areas of the corresponding first or second sub-waveguide, or to guide a light beam from any selected second surface area of ​​the at least two second surface areas of the corresponding first or second sub-waveguide to the first surface area of ​​the corresponding first or second sub-waveguide, and the light beam is coupled into or out of the corresponding first or second sub-waveguide via the first surface area of ​​the corresponding first or second sub-waveguide and the selected second surface area of ​​the corresponding first or second sub-waveguide optically coupled to the first surface area of ​​the sub-waveguide, and the at least one guiding element of each of the first or second sub-waveguide can be configured to switch the guiding of the light beam between the at least two second surface areas of the corresponding first or second sub-waveguide by at least one of changing the optical properties of the at least one guiding element and modulating at least one light beam characteristic.

3. The multimode optical waveguide network of claim 1, wherein at least one of the guiding elements comprises an active guiding element.

4. A multimode optical waveguide network according to claim 3, wherein the active guiding element comprises at least one of the following: a configurable transmittance or reflectivity, a configurable refractive index, a switchable grating or a switchable grating region.

5. The multimode optical waveguide network of claim 1, wherein at least one of the guiding elements is responsive to the at least one optical beam characteristic.

6. The multimode optical waveguide network of claim 1 , wherein the parent waveguide comprises at least one wavelength-responsive guiding element such that a light beam in a first wavelength range is guided from the first surface area of ​​the parent waveguide into the first child waveguide or from the first child waveguide toward the first surface area of ​​the parent waveguide, and a light beam in a second wavelength range is guided from the first surface area of ​​the parent waveguide to the second child waveguide or from the second child waveguide toward the first surface area of ​​the parent waveguide; wherein the first sub-waveguide has at least one wavelength responsive guiding element, so that a light beam within a first sub-range of the first wavelength range is guided from the first surface area of ​​the first sub-waveguide to one of the at least two second surface areas of the first sub-waveguide or from the one second surface area of ​​the at least two second surface areas of the first sub-waveguide to the first surface area of ​​the first sub-waveguide, and a light beam within a second sub-range of the first wavelength range is guided from the first surface area of ​​the first sub-waveguide to the other second surface area of ​​the at least two second surface areas of the first sub-waveguide or from the other second surface area of ​​the at least two second surface areas of the first sub-waveguide to the first surface area of ​​the first sub-waveguide; as well as The second sub-waveguide has at least one wavelength response guiding element, so that the light beam within the first sub-range of the second wavelength range is guided from the first surface area of ​​the second sub-waveguide to one of the at least two second surface areas of the second sub-waveguide or from the one second surface area of ​​the at least two second surface areas of the second sub-waveguide to the first surface area of ​​the second sub-waveguide, and the light beam within the second sub-range of the second wavelength range is guided from the first surface area of ​​the second sub-waveguide to the other second surface area of ​​the at least two second surface areas of the second sub-waveguide or from the other second surface area of ​​the at least two second surface areas of the second sub-waveguide to the first surface area of ​​the second sub-waveguide.

7. The multimode optical waveguide network of claim 1, wherein at least one of the guiding elements comprises an active guiding element and at least another of the guiding elements comprises a guiding element responsive to the at least one optical beam characteristic.

8. The multimode optical waveguide network of claim 1, wherein at least one of the guiding elements comprises at least one of a wavelength filter and a polarization filter having at least one of a fixed wavelength response, a configurable wavelength response, a fixed polarization axis, and a configurable polarization axis.

9. The multimode optical waveguide network of claim 1, wherein at least one of the parent waveguide, the first sub-waveguide, and the second sub-waveguide has two or more guiding elements and three or more second surface areas.

10. An optical system comprising: a first optical system component; a plurality of second optical system components; at least one multimode optical waveguide network, the multimode optical waveguide network being arranged to direct an optical beam from the first optical system component to any selected second optical system component of the plurality of second optical system components, or to direct an optical beam from any selected second optical system component of the plurality of second optical system components to the first optical system component, the at least one multimode optical waveguide network comprising: a parent waveguide; and a first sub-waveguide and a second sub-waveguide; wherein each of the parent waveguide and the first and second sub-waveguides is a multimode optical waveguide having a first surface area, at least two second surface areas, and at least one guiding element, wherein at least one of the second surface areas of the parent waveguide is optically coupled to the first surface area of ​​the first sub-waveguide, and wherein at least another of the second surface areas of the parent waveguide is optically coupled to the first surface area of ​​the second sub-waveguide; and wherein the at least one guiding element of the parent waveguide is arranged to guide a light beam from the first surface area of ​​the parent waveguide to any selected second surface area of ​​the at least two second surface areas of the parent waveguide or to guide a light beam from any selected second surface area of ​​the at least two second surface areas of the parent waveguide to the first surface area of ​​the parent waveguide, the light beam is coupled into or received from the corresponding first sub-waveguide or second sub-waveguide via the selected second surface area of ​​the parent waveguide and the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide, the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide is optically coupled to the selected second surface area of ​​the parent waveguide, the at least one guiding element of each of the first sub-waveguide and the second sub-waveguide a guiding element arranged to guide a light beam from the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide to any selected second surface area of ​​the at least two second surface areas of the corresponding first sub-waveguide or second sub-waveguide or to guide a light beam from any selected second surface area of ​​the at least two second surface areas of the corresponding first sub-waveguide or second sub-waveguide to the first surface area of ​​the corresponding first sub-waveguide or second sub-waveguide, wherein the at least one guiding element of each of the parent waveguide, the first sub-waveguide and the second sub-waveguide is configurable to switch the guiding of the light beam between the at least two second surface areas of the waveguide via at least one of changing an optical property of the at least one guiding element, modulating at least one light beam characteristic; and A controller is configured to select a second optical system component from the plurality of second optical system components, and direct the light beam from the first optical system component to the selected second optical system component or direct the light beam from the selected second optical system component to the first optical system component by configuring at least one guiding element of the multimode optical waveguide network and modulating at least one of the at least one light beam characteristic.

11. The optical system according to claim 10, wherein: The first optical system component comprises: an emitter system from which a light beam is emitted and directed toward a selected component of the second optical system, or A detector array, toward which a light beam is directed from the selected second optical system component.

12. The optical system of claim 11, wherein at least one of the first optical system component and the second optical system component comprises: a signal converter configured to convert a light beam into an electrical signal or to convert an electrical signal into a light beam, or Optical processor.

13. The optical system of claim 10, wherein at least one of the guiding elements comprises an active guiding element.

14. The optical system of claim 10, wherein at least one of the guiding elements comprises an active guiding element having at least one of: a configurable transmittance or reflectance, a configurable refractive index, a switchable grating, or a switchable grating region.

15. An optical system comprising: a first optical system component; a multimode optical waveguide network arranged to direct an optical beam from the first optical system component to the second optical system component, or from the second optical system component to the first optical system component; as well as A controller is configured to select the second optical system component and guide the light beam from the first optical system component to the selected second optical system component, or from the selected second optical system component to the first optical system component, by changing at least one of the optical properties of the guiding element of the multimode optical waveguide network and modulating the light beam characteristics.

16. The optical system of claim 15, wherein the first optical system component comprises: an emitter system from which a light beam is emitted and directed toward a selected component of the second optical system, or A detector array, toward which a light beam is directed from the selected second optical system component.

17. The optical system of claim 16, wherein at least one of the first optical system component and / or the second optical system component comprises: a signal converter configured to convert a light beam into an electrical signal or to convert an electrical signal into a light beam, or Optical processor.

18. The optical system of claim 16, comprising one or more holographic recording media, wherein at least some of the second system optical components are respective sub-volumes of the one or more holographic recording media.

19. The optical system of claim 15, comprising a second multimode optical waveguide network, the controller being configured to direct a second optical beam from the first optical system component to the same selected second optical system component or to direct the second optical beam from the same selected second optical system component to the first optical system component by configuring at least one guiding element of the second multimode optical waveguide network and / or modulating at least one beam characteristic.

20. The optical system of claim 19, comprising a third multimode optical waveguide network, the controller being configured to direct a third optical beam from the first optical system component to the same selected second optical system component or to direct the third optical beam from the same selected second optical system component to the first optical system component by configuring at least one guiding element of the third multimode optical waveguide network and / or modulating at least one beam characteristic.

Images