Data transfer and processing

Abstract

An apparatus 10 comprises: an optical component 130 to perform a first mathematical operation on a set of optical input signals 140 by transforming the set to produce different optical output signals

Description

Field The present disclosure relates to devices, apparatuses, systems and methods for data transfer and processing. More particularly, the present disclosure relates to optical or photonic devices, apparatuses, systems and methods for data transfer and processing. The present disclosure also relates to network connections and computer networks. More particularly, the present disclosure relates to optical network connections, and computer networks. Background Data transport is a critical operation in modern computing hardware architectures and computer networking in general. Data exchange is critical between different computing and communication hardware entities and systems such as: integrated circuit (IC) chiplets, network on chips (NOCs), system on chips (SoCs), multi-chip modules (MCMs), disaggregated nodes, memory modules, graphics or graphical processing units (GPUs), tensor processing units (TPUs), high bandwidth memory (HBM), server blades, motherboards, sensors and actuators, and data transmitters and receivers. Data exchange between hardware entities and systems are traditionally performed using electrical and / or photonic signals. Examples of the conduits through which these signals are transported include interposers, printed circuit boards (PCBs), direct attach cables (DACs) or metal wires, optical fibres, and photonics. Data exchange between physical computing entities can occur over varying physical distances and depend on the system architecture. Typical data exchanges may occur between chiplets within MCMs and SoCs via interposers, between chiplets and HBMs within MCMs and SoCs via interposers, between packaged ICs on a PCB via metal traces, between PCBs (e.g., motherboards, server blades, GPUs, TPUs, or memory modules) via DACs, optical fibres, electrical cables or photonics. The distances may be very short (of the order of mm) up to several km or more. The communications may be ultra short reach ‘USR’ (e.g. for communication between GPUs / servers / data centre nodes), medium reach, or long range. The above building blocks allow sophisticated data communication and networking infrastructures used in, for example, data centres, wired telecommunication networks, metro and long-haul communications systems, scientific computing infrastructures, supercomputers, and disaggregated networks. The systems and subsystems for data transport over a physical media typically fall under layer 1 or the Physical (PHY) Layer of an Open Systems Interconnection (OSI) Model from the International Organisation for Standardization (ISO). The PHY is the bottom-most layer of the OSI Model and is a physical and electrical representation of the system. Recently, photonics-based systems are also being used in the forming of (or are formed in) the PHY layer. Data communication networks and physical layers are typically designed for data transport and exchange only. Even though raw data is processed (by, for example, encoding, forward error correction (FEC), cyclic redundancy checks (ORC), message packing, etc.) in preparation for transmission, and data received by a receiver of a data communication network is processed (by, for example, decoding, FEC, CRC, message unpacking, etc.) by the receiver to form the original data. Therefore, it is intended that the unpacked / decoded received data is the original data. There exists a need to improve and enhance present data communication systems greater use is made of data transport hardware and data exchange processes between the network interfaces of different hardware components. Summary An invention is defined in the appended claims. Brief description of the drawings The following description of the disclosure will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the optical apparatuses and methods shown and described and that other configurations are possible. In the drawings: Figure 1 depicts an optical apparatus according to a first example; Figure 2 depicts an optical apparatus according to a second example; Figure 3 depicts an optical apparatus according to a third example; Figure 4a shows a schematic of an optical Fourier transform apparatus; Figure 4b shows a schematic of an optical Fourier transform apparatus showing an example of an arrangement of input and output ports; and Figure 5 shows an optical circuit diagram of a photonic integrated circuit including an optical Fourier transform apparatus. Detailed description In overview, the present disclosure relates to an apparatus and method that allows simultaneous data transportation and data processing between hardware components in a network. Data processing is completed on the fly between the network interface of a first hardware component and the network interface of a second hardware component by transmitting the data optically and adopting an optical circuit or other optical device or optical apparatus arranged to perform a mathematical operation on the data sent by the first hardware component so that the data received at the second hardware component is calculated from that transmitted by the first hardware component whilst the data is being transported. PHY layers used in current computing and networking architectures are not maximally utilised to perform processing of data, for example arithmetic or other mathematical processing of data. The inventors propose that data can be processed optically between network interfaces of different hardware components so that the data received by a receiver in one hardware component is the result of mathematical operations performed on input data transmitted by the transmitter of another (separate) hardware component. That is, the data path between network interfaces can be used to mathematically process data optically whilst the data is transported between hardware components. In other words, the inventors have recognised that use of the connections between network interfaces can be increased or maximised if optical processing of transmitted signals (for the purposes of mathematically processing the data carried by these signals) is built in to the data transport path. The inventors have further recognised that if the input data sent by the transmitter is divided between separate optical channels, then a mathematical operation having the data from each channel as an operand can happen within the data transport link between the transmitter and receiver, and the result of the mathematical operation can be received at the receiver. This allows mathematical operations to be performed optically on-the-fly between hardware components, for example between network nodes in a network. An effect of this is the reduction in the need for processing circuitry and operations in one or both of the hardware components between which data is transmitted. Particularly useful mathematical operations include Fourier transforms and convolutions. Fourier transforms and convolutions benefit applications such as those involving the processing of encrypted data (e.g. in Fully Homomorphic Encryption, FHE). Data can be processed or interrogated without first decrypting, thereby improving data security. However, the present disclosure is not necessarily limited to Fourier transforms and convolutions and other mathematical operations during data transport are envisaged, such as arithmetic operations (e.g. multiplication, addition and subtraction). The optical component may be configured so that the mathematical operation acts on either the phase, the amplitude, or both. For example, the amplitude may be multiplied, or the phase may be shifted or both. Mathematical operations may include one or more mathematical sub-operations. For example, the mathematical operation includes a first mathematical sub-operation, and a second mathematical sub-operation which acts on the result of the first mathematical sub-operation to produce the result of the two operations. The mathematical operations can be ‘hardwired’ into the optical component arranged to perform the mathematical operation. That is, the mathematical operation itself (rather than the data input or output from the operation) is a function of the hardware layout. In this sense, the optical component is passive. This provides an advantage in that no additional power is required to perform the mathematical operation. The data processing comes, in terms of power consumption, for free as part of the data transport. Such passive components can include an optical circuit including two or more input channels (each originating at a respective transmitter of one hardware component) and at least one output channel (each terminating at a receiver of another hardware component). For example, if the mathematical operation is a Fourier transform or convolution, the optical component can be passive in the sense that it is configured to perform an optical Fourier transform of any optical signals applied at its input interface (e.g. input ports formed as the terminus of the two or more input channels) regardless of the input data values. The optical Fourier transform of an input function represented by the signals transmitted by the first hardware component is always the output function represented by the signals received at the output interface (e.g. output ports formed as the entry to the two or more output channels) of the optical component, which are then received at the second hardware component. Likewise, if the mathematical operation performed by the optical component is addition, the optical component can be a (passive) combiner circuit arranged so that the set of optical input signals transmitted by the first hardware component are combined optically by the arrangement of the hardware to form the at least one optical output signal. The combiner may be a NxM branched junction, wherein N is the number of input channels (e.g. two or more) and M is the number of output channels (usually one). In both of these examples, the first hardware component is arranged to simultaneously transmit each optical input signal of the first set of optical input signals to first optical component, and the second hardware component is arranged to simultaneously receive each optical output signal of the first set of optical output signals from the first optical component. The two or more hardware components between which data is simultaneously transmitted and processed can be described as being a network or part thereof. In this case, the hardware components, or their network interfaces, can be described as nodes of the network. In this sense, a mathematical operation is carried out by an optical component on the data sent from one node and the result of the mathematical operation is sent to another node, thereby performing data processing during data transport between (network) nodes of a network. The data can be said to flow between nodes through an optical data transport link which includes the optical component doing the maths and the input and output channels. The apparatuses, systems, networks and methods described in the present disclosure provide a modular and scalable optical or photonic technology that can perform both data transport and computation (or data transport and processing) simultaneously. Parallelisation of data transmission and computation can be carried out on the PHY layer. By offloading specific computations or parts thereof from a main processing unit into data transport units, the overall computational burden on one or more hardware components of the system can be reduced and a more compact and resource-efficient system can be provided without compromising on computational capacity and / or utility. This results in improved overall system performance and / or lower energy requirements and / or a more compact and simpler system architecture. By performing certain mathematical operations, such as data preprocessing or compression, during data transport, data size and / or complexity can be reduced before transmission to the main memory, thereby resulting in faster memory accesses, reduced memory latency, and improved overall system responsiveness. Furthermore, the provision of data processing during transportation between network interfaces can provide another degree of freedom in computer architecture design leading to new possibilities for processing, accessing and storing data not possible (or at least less efficient, less compact or less resource-intensive than) using traditional computer architectures. The input data may be sent in frames and the frame rate can allow data transmission frequencies of several MHz or even GHz (or even greater) of data transmission over the data transport link. The preceding overview is provided to introduce in simplified form a selection of concepts that are further described herein. The overview is not intended to identify key or essential features of the invention. The following detailed description of the drawings is intended to be read in the context of the preceding overview and is not intended to be limiting. Figure 1 depicts an optical apparatus 10, or networking apparatus, according to a first example. The optical apparatus represents the PHY layer of the OSI Model. The optical apparatus 10 comprises a first optical component 130 that is configured to receive a set of optical input signals (or a set of optical input streams) 140a, ..., 140n transmitted (or output) by a first set of transmitters (or first to nth transmitters) 100a, ..., 100n of a first hardware component (or a first subsystem or a first host) 120. The set of optical input signals 140a, ... 140n are processed by the first optical component 130 applying a first mathematical operation or function to produce a set of optical output signals (or a set of optical output streams) 141a, ..., 141n. The set of optical output signals 141a, ..., 141 n are transmitted to a second hardware component (or a second subsystem or a second host) 121 and received by a first set of receivers (or first to nth receivers) 110a, ..., 110n of the second hardware component 121. Hence, data is transmitted from the first hardware component 120 to the second hardware component 121, while simultaneously performing the first mathematical operation on the data 140a, .... 140n. Throughout the present disclosure, the term “processed”, when used in the context of how the optical component acts on the input signals, means that the input signals (or data carried thereon or encoded thereto) are the operands in a mathematical calculation or operation to produce the mathematical result in at least one optical output signal (or data carried thereon or encoded thereto). For example, data encoded onto the set of optical input signals is (or comprises) the mathematical inputs (or operands) and data decoded from the at least one optical output signal is (or comprises) the mathematical result. The first hardware component 120 includes a first network interface and the second hardware component 121 includes a second network interface. In embodiments, the first network interface is different from the second network interface. For example, the first network interface comprises a first (e.g. unique) identifier and the second network interface has a second (e.g. unique) identifier different from the first identifier. Examples of suitable identifiers are a MAC address (e.g. EUI-48), burned-in address, physical address or ethernet hardware address assigned to a network interface controller. Each of the other hardware components described herein (e.g. those described with reference to Figures 2 and 3) also comprises its own network interface, which may have the same features and function as the network interface of the first and second hardware components, aside from the network identifier, which in some embodiments is unique to the hardware component. The identifier is, for example, either a universally administered address (UAA) or locally administered address (LAA). The first set of transmitters 100a, ..., 100n are arranged to transmit each respective optical input signal 140a, ..., 140n from the first hardware component 120 to the first optical component 130. The first set of receivers 110a, ..., 110n are arranged to receive each respective optical output signal 141a, ..., 141 n from the first optical component 130 at the second hardware component 121. In more general terms, the optical apparatus 10 of Figure 1 comprises a first optical component 130, a first hardware component 120, and a second hardware component 121. The first optical component 130 is arranged to perform a first mathematical operation on a first set of optical input signals 140a, ..., 140n to produce at least one first optical output signal 141a different from the first set of optical input signals 140a, ..., 140n. The mathematical operation is carried out on the data represented by the first set of optical signals - the operands of the mathematical operation. The data represented by the at least one first optical output signal - the result of the mathematical operation - is different from the data represented by the first set of optical input signals. For example, the first set of optical input signals 140a, ..., 140n are modulated to encode an input data onto each input signal, the mathematical operation is performed by the first optical component 130 on the input data, and resulting output data is automatically encoded onto each of the at least one first optical output signals. The first hardware component 120 is configured to encode the data onto the first set of optical input signals 140a, ..., 140n and transmit the first set of optical input signals to the first optical component 130 and the second hardware component 121 is configured to receive the at least one first optical output signal 141a from the first optical component 130. The output data is derived (or decoded) from the at least one first optical output signal 141a received by the second hardware component 121. The first and second hardware components 120,121 are separate and / or distinct components in that each has its own network interface. This does not necessarily mean that the first and second hardware components are physically separate (although in some embodiments hardware components are physically separate in this way, for example the hardware component are separated from one another by a distance of at least 1mm, at least 5mm, at least 10mm, at least 25mm, at least 50mm, or at least 100mm). For example, the first and second hardware components can be chips or other components on the same circuit board or can be physically linked or attached to each other in other ways. The hardware components may be communicatively isolated (e.g. optically and / or electronically isolated) from each other so that the only operative (or communication) connections directly between them are those that are necessary for the transmission of the data or the processing of the data by the optical component performing the mathematical operation on the transmitted data. The hardware components may be connected to a common power supply, thermal management system, clock or other synchronization mechanism, however. The optical data transport and processing devices of the present disclosure are distinct from known optical data processing devices in that they transport data between network interfaces. That is, data processing (in particular the mathematical operation) occurs between network interfaces and at the same time is at least part of the data transport route or connection between the first and second hardware components. Returning to Figure 1, at least one first optical output signal 141 a may comprise a first set of optical output signals 141a, ..., 141 n, as depicted in Figure 1. This is especially useful when the first mathematical operation is Fourier transform or convolution because the full Fourier transform of an input function represented by the first set of optical input signals 140a, ..., 140n can be represented more accurately by a set of optical output signals (as opposed to just one). Therefore, the optical apparatus 10 described herein is capable of performing two roles or functions. These functions are transferring data between a first hardware component 120 and a second hardware component 121 (i.e., a data transmission / data transport process), and performing a mathematical operation on the data during data transfer (i.e., computation, processing, or mathematical operations during data transmission). Thus, parallelisation of data transmission and computation is achieved on the PHY layer. The parallelisation allows specific computations to be offloaded from a main processing unit into data transport units. This can reduce the overall computational burden on the entire system, enhance computing capabilities, and / or improve overall system performance. If the first or second hardware component includes a computer memory, the mathematical operation can increase the speed of accessing (reading from or writing to) memory by performing certain operations, such as data preprocessing or compression, during data transport, thereby reducing the data size or complexity before transmission to the main memory. Consequently, this results in reduced memory latency and improved overall system responsiveness. The apparatus may be radix 2N or 4N, where N is a positive integer, alternatively, the apparatus may be radix 2n or 4n, where n is a positive integer, in that the first set of optical input signals comprises 2N, 4N, 2n or 4n input signals and the first set of optical output signals comprises 2N, 4N, 2n or 4n output signals. When the mathematical operation is a Fourier transform or convolution, it can be advantageous for the number of optical input signals to be equal to the number of optical output signals for the purposes of simplifying the input and output data sorting algorithms. For example, the first set of transmitters 100a, .... 100n comprises four transmitters and the first set of receivers 110a, ..., 110n comprises four receivers, so that there are four first optical input signals and four first optical output signals. In another example, the first hardware component 120 may comprise at least two transmitters and the second hardware component 121 may comprise at least two receivers. In an embodiment where only one first optical output signal 141a is produced by performing a mathematical operation on the first set of optical input signals 140a.....140n, the second hardware component 121 may comprise one receiver 110a only. In such an implementation, the mathematical operation includes an addition or subtraction of optical input signals in the first set of optical input signals to form a single resulting optical output signal which is the sum of the optical input signals. In general, each hardware component comprises a transmitter arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component, and / or a receiver arranged to receive each respective optical output signal received at the respective hardware component, and / or a transceiver arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component and receive each respective optical output signal received at the respective hardware component. In the example of Figure 1, or more controllers in the first hardware component 120 are configured to operate the first set of transmitters 100a, ..., 100n in the first hardware component 120 to modulate the first set of optical input signals 140a, ..., 140n to carry input data values based on input data input to the first set of transmitters 100a, ..., 100n. Each transmitter of the first set of transmitters 100a, ..., 100n is configured to transmit an optical input signal of the first set of optical input signals 140a, ..., 140n. A first set of input channels is configured to carry the first set of optical input signals 140a, ..., 140n to the first optical component 130. Each of the input channels extend from a respective transmitter of the first set of transmitters 100a, ..., 100nto the first optical component 130. Each input channel may take the form of the input channels described with reference to Figure 4a, 4b and / or Figure 5. Each transmitter of the first set of transmitters 100a, ..., 100n includes an encoder configured to modulate the first set of optical input signals 140a, ..., 140n based on a data value input to the encoder. Encoders included in the first hardware component 120 enable the first set of transmitters 100a.....100n to apply modulation to the first set of optical input signals 140a.....140n so as to encode data onto the input signals. To this end, in some embodiments, the first hardware component comprises at least one electronic circuit configured to provide data to be encoded onto the first set of optical input signals. Examples of suitable transmitters are described with reference to Figure 5 (for example with reference to transmitter 540 of Figure 5). The first optical component 130 is configured to perform a mathematical operation, for example, one or more of addition, subtraction, multiplication, Fourier transform, or convolution, on the first set of optical input signals 140a, ..., 140n to generate the at least one first optical output signal 141a, ..., 141 n. Each respective mathematical operation may comprise a plurality of mathematical suboperations. If the mathematical operation is Fourier transform or multiplication in Fourier space (e.g. as involved in a convolution), the first optical component 130 is an optical Fourier transform stage configured to perform a Fourier transform operation on the input data or an inverse Fourier transform operation on the input data 140a, ..., 140n. If the first optical component 130 is an optical Fourier transform stage, the data values encoded onto the first set of optical input signals 140a, ..., 140n represent an input function as an input to the Fourier transform stage. Decoders in the first set of receivers 110a, ..., 110n in the second hardware component 121 are arranged to determine the data from the at least one first optical output signal 141a.....141 n by decoding the signals. Each receiver of the first set of receivers 110a, ..., 11 On is configured to receive an optical signal of the at least one first optical output signals 141a, ..., 141 n via an output channel of a first set of output channels of the first optical component 130 extending from to the first optical component 130 to the first set of receivers 110a, ..., 110n. Hence, an output channel of the first optical component 130 is arranged to carry each respective optical output signal 141a, ..., 141 n. Each output channel may take the form of the output channels described with reference to Figure 4a, 4b and / or Figure 5. The input and output channels may be optical channels, for example waveguides. Suitable channels and waveguides are described with reference to Figure 4a. The sets of input and output channels facilitate optical signal transfer between the first hardware component 120 and the second hardware component 121 via the first optical component 130. The first optical component 130 is connected to the sets of input and output channels in a way that allows a mathematical operation, such as, for example, one or more of addition, subtraction, multiplication, Fourier transform, or convolution, to be carried out optically on the first set of optical input signals 140a, ..., 140n during data transmission between the first hardware component 120 and the second hardware component 121. Each receiver of the first set of receivers 110a, ..., 110n includes a decoder configured to decode a data value encoded onto the first set of optical output signals 141a, ..., 141n received by the decoder. In some embodiments, the second hardware component comprises at least one electronic circuit configured to receive, read, store, process, and / or onwardly transmit data decoded from the at least one optical output signal. Examples of suitable receivers are described with reference to Figure 5 (for example with reference to transmitter 570 of Figure 5). If the mathematical operation is Fourier transform or convolution, the first optical component 130 is an optical Fourier transform stage and the first set of optical output signals 141a.....141 n output from the Fourier transform stage are encoded with values representing an output function, which is the Fourier transform of the input function. The first set of optical output signals 141a, ..., 141 n are transmitted through the output channels to the second hardware component 121. The first set of receivers 110a, ..., 110n in the second hardware component 121 decode data values from the first set of optical output signals 141a, ..., 141 n so as to determine the result of the Fourier transform of the data encoded onto the optical input signals 140a, ..., 140n. As an example, the encoders in the first hardware component 120 included in the first set of transmitters 100a, ..., 100n apply modulation to the first set of optical input signals 140a, ..., 140n. If the first optical component 130 is an optical Fourier transform stage, the values encoded onto the first set of optical input signals 140a, ..., 140n represent an input function as an input to the Fourier transform stage. The first set of optical output signals 141a, .... 141 n output from the Fourier transform stage are encoded with values representing an output function, which is the Fourier transform of the input function. The first set of optical output signals 141a, ..., 141 n are transmitted through the optical channels to the second hardware component 121. As already described herein, the first set of receivers 110a, ..., 110n in the second hardware component 121 include decoders arranged to decode data values from the first set of optical output signals 141a, ..., 141 n so as to determine the result of the Fourier transform of the data encoded onto the optical input signals 140a, .... 140n. Figure 1 is an example of simplex communication between two hardware components via a first optical component. However, as described with reference to Figure 2, the apparatuses of the present disclosure may operate in half duplex or full duplex mode allowing two-way communication between two or more hardware components for example via a first and second optical component. Half duplex mode between two hardware components is also described, for example, with reference to Figure 3 in relation to the communication between the second and third hardware components 321,322 via the second optical component 331. The optical input and output signals 140a, ..., 140n, 141a, ..., 141n may be monochromatic. In some embodiments, the input signals are coherent, but the present disclosure is not limited thereto and in alternative embodiments different phases are applied to each input signal. Each respective hardware component 120,121 may comprise or form a part of one or more of an IC chiplet, a NOC, a SoC, an MCM, a memory module, a GPU, a TPU, a server blade, a motherboard, a disaggregated node, a HBM, a sensor, an actuator, a data transmitter, and a receiver. The any of the optical components described herein may comprise one or more of an OFT stage, a combiner, a phase shifter, a waveguide, and an intensity modulator. The respective hardware components 120, 121 may be arranged to be separated from one another by a distance of at least 1mm, at least 5mm, at least 10mm, at least 25mm, at least 50mm, or at least 100mm, or at least 500m (or ultra short reach ‘USR’, e.g. for communication between GPUs / servers / data centre nodes)., or at least 2km (or medium reach), or at least 10km (or long range) Each optical output signal is different from its respective optical input signal. The description of the form, fabrication and function of the apparatus described with reference to Figure 1, as well as other statements herein (e.g. in the claims or overview section), may apply equally to the pair of any two other communicating hardware components described in the foregoing with reference to Figures 2 and 3 except where stated otherwise. This includes, for example, the form, fabrication and function of: • the first and second hardware components 220, 221 in Figure 2, and their communication via the first or second optical component 230, 231; • the first and second hardware components 320, 321 in Figure 1, and their communication via the first optical component 330; • the second and third hardware components 321,322 in Figure 3, and their communication in either direction (depending on the operating mode of the transceivers) via the second optical component 331, • the fourth and first hardware components 323, 320 in Figure 3, and their communication via the fifth optical component 334, • the first and fourth hardware components 320, 323 in Figure 3, and their communication via the first and fourth optical component 330, • the third hardware component 322 and its communication with itself via the third optical component 332. Therefore the following description of Figures 2 and 3 omits or abbreviates many of the other details already described herein as far as they relate to two communicating hardware components, input / output signals, and the associated optical component through which signals are transported, except where stated otherwise. For example, the description above in relation to the function and / or form of a first optical component 130 equally applies to any other optical component described herein (e.g., the second optical component described with reference to Figure 2 and / or Figure 3, and / or the third and / or fourth optical component described with reference to Figure 3). The description above in relation to the function and / or form of first set of transmitters 100a, ...,1 OOn equally applies to any other set of transmitters described herein (e.g., the second set of transmitters). The description above in relation to the function and / or form of first set of receivers 110a, ..., 110n equally applies to any other set of receivers described herein (e.g., the second set of receivers). The description above in relation to the function and / or form of the first set of optical input signals 140a, ..., 140n equally applies to any of the optical input signals described herein, for example the third, fifth, or seventh set of optical input signals. The description above in relation to the function and / or form of the at least one first optical output signal or the first set of optical output signals 141a, .... 141 n equally applies to any of the optical input signals described herein, for example the fourth, sixth, or eighth set of optical output signals. Figure 2 depicts an optical apparatus 20 according to a second example. In Figure 2, the optical apparatus 10 comprises a first optical component 230 that is configured to receive a first set of optical input signals 240a, ..., 240n transmitted by a first set of transmitters 200a, .... 200n of a first hardware component 220. The first set of optical input signals 240a, ... 240n are processed by the first optical component 230 applying a first mathematical operation or function to produce a first set of optical output signals 241a, ..., 241 n. The first set of optical output signals 241a, ..., 241 n are transmitted to a second hardware component 221 and received by a first set of receivers 210a, ..., 21 On of the second hardware component 221. Hence, data is transmitted from the first hardware component 220 to the second hardware component 221, while simultaneously performing the first mathematical operation on the data 240a.....240n, as described in relation to Figure 1. In addition, the optical apparatus 20 further comprises a second optical component 231 that is configured to receive a second set of optical input signals 242a, ..., 242n transmitted by a second set of transmitters 201a, ..., 201n of the second hardware component 221. The second set of optical input signals 242a, ... 242n are processed by the second optical component 231 applying a second mathematical operation or function to produce at least one second optical output signal (e.g. a second set of optical output signals 243a, ..., 243n). The second set of optical output signals 243a, ..., 243n are transmitted to the first hardware component 220 and received by a second set of receivers 211a, ..., 211 n of the first hardware component 220. Hence, data is transmitted from the second hardware component 221 to the first hardware component 220, while simultaneously performing the second mathematical operation on the data encoded onto the optical input signals 242a, ..., 242n. Hence, the first hardware component 220 comprises the first set of transmitters 200a, ..., 200n and the second set of receivers 211a, ..., 211 n, and the second hardware component 221 comprises first set of receivers 210a, ..., 210n and the second set of transmitters 201a, ..., 201n. The respective hardware components 220, 221 may be arranged to simultaneously transmit each optical input signal of the respective set of optical input signals 240a, ..., 240n, 242a, ... 242n to respective optical components 230, 231. The respective hardware components 220, 221 may be arranged to simultaneously receive each optical output signal of the respective at least one optical output signals 241a, ..., 241 n, 243a, ..., 243n from respective optical components 230, 231. Therefore, data processing can be parallelized and simultaneous, resulting in higher throughput and / or greater computational speed. Figure 3 depicts an optical apparatus 30 according to a third example. The optical apparatus 30 comprises a first optical component 330 that is configured to receive a first set of optical input signals 340a, ..., 340n transmitted by a first set of transmitters 300a, ..., 300n of a first hardware component 320. The first set of optical input signals 340a, ... 340n are processed by the first optical component 330 applying a first mathematical operation or function to produce a first set of optical output signals 341a, .... 341 n. The first set of optical output signals 341a, .... 341 n are transmitted to a second hardware component 321 and received by a first set of receivers 310a, ..., 31 On of the second hardware component 321. Hence, data is transmitted from the first hardware component 320 to the second hardware component 321, while simultaneously performing the first mathematical operation on the data encoded onto the optical input signals 340a, ..., 340n, as described in relation to Figure 1. The optical apparatus 30 further comprises a third hardware component 322. The third hardware component 322 is a separate and distinct component from the first and second hardware components 320, 321. The third hardware component 322 described herein may relate to a first, second, fourth, ..., nth hardware component or may comprise a plurality of hardware components. The wording “third” hardware component is merely provided as a way of numbering the hardware components and this in no way limits the optical apparatus 30 to first, second and third hardware components only. Any of the functions of any of the hardware components described herein may be carried out by an nth hardware component. The third hardware component 323 has its own network interface, thereby allowing it to be formed as part of a network including the first and / or second hardware components. The third network interface is different from the first and second network interface. The third network interface may have a third identifier different from the first identifier and second identifier, wherein the third identifier may take the same format (but not necessarily the same identity) as the first and second identifiers, such as a MAC address. The third hardware component 323 may be separate or distinct from the first and second hardware components, e.g. communicated isolated from or physically separate from the first and second hardware components as the first and second hardware components are separate or distinct from each other. The optical apparatus 30 further comprises a second optical component 331 configured to receive a second set of optical input signals 342a, ..., 342n transmitted by a first set of transceivers 350a, ..., 350n of the second hardware component 321. The second set of optical input signals 342a, ..., 342n are processed by the second optical component 331 applying a second mathematical operation or function to produce a second set of optical output signals 343a, ..., 343n. The second set of optical output signals 343a, ..., 343n are transmitted to the third hardware component 322 and received by a first set of transceivers 351a, .... 351 n of the third hardware component 322. Hence, data is transmitted from the second hardware component 321 to the third hardware component 322, while simultaneously performing the second mathematical operation on the data encoded onto the optical input signals 342a, ..., 342n. As the second and third hardware components 321,322 comprise transceivers, this operation may happen in reverse so that the second optical component 331 is configured to receive a second set of optical input signals 343a, ..., 343n transmitted by the second set of transceivers 351a, ..., 351 n of the third hardware component 322. The second set of optical input signals 343a, ..., 343n are processed by the second optical component 331 applying a second mathematical operation or function to produce a second set of optical output signals 342a, ..., 342n. The second set of optical output signals 342a, ..., 342n are transmitted to the second hardware component 321 and received by the first set of transceivers 350a, ..., 350n of the second hardware component 321. Hence, data is transmitted from the third hardware component 322 to the second hardware component 321, while simultaneously performing the second mathematical operation on the data 342a, ..., 342n. Optical Fourier transform stages, for example, can be configurable (or by their nature are ready configured) to perform the same mathematical operation (FT) regardless of signal flow direction and so the same optical component can be used to perform the same mathematical operation regardless of signal flow direction in this case. For other optical components, a different mathematical operation can happen in the reverse direction. For example, for a combiner arranged to perform an addition operation in a forward signal flow direction, there may be merely a splitting of the input signal in the reverse signal flow direction. In some embodiments in which each hardware component includes a set of transceivers in communication with the optical component (such as that described with reference to second optical component and its connection to the second and third hardware components in Figure 3), the optical component may have plurality of mathematical functions to account for bi-directional communication between the transceivers. For example, a set of optical input signals arriving at an optical component (e.g. the second optical component in Figure 3) from one hardware component (e.g. the second hardware component in Figure 3) undergo a first mathematical operation due to the configuration of the optical component. At least one optical output signal (the result of the first mathematical operation) is received at another hardware component (e.g. the third hardware component in Figure 3). In the opposite direction, optical input signals arriving at the optical component from the other hardware component (e.g. the third hardware component in Figure 3) undergo a second mathematical operation different from the first mathematical operation due to the configuration of the optical component. At least one optical output signal (the result of the second mathematical operation) is received at the one hardware component (e.g. the second hardware component in Figure 3). In the preceding examples including the first and second optical components 330, 331, the simultaneous data transportation and processing is carried out between different components because the first hardware component is different from the second hardware component. Therefore, in those examples, the first network interface (associated with the first hardware component) is different from the second network interface (associated with the second hardware component). In another example shown in Figure 3, data can be transported out of a hardware component (in this case, a third hardware component 322) and then back into the same hardware component again while data processing is performed during data transport by a third optical component. Therefore, the hardware component from which data is sent is the same hardware component at which the processed data is received. In this case, the first and second network interfaces can be one and the same or can be different network interfaces included in the same hardware component. For example, the optical apparatus 30 further comprises a third optical component 332 configured to receive a third set of optical input signals 344a, ..., 344n transmitted by a third set of transceivers 352a, ..., 352n of the third hardware component 322. The third set of optical input signals 344a, ..., 344n are processed by the third optical component 332 applying a third mathematical operation or function to produce at least one third optical output signal (e.g. a third set of optical output signals 345a, ..., 345n). The third set of optical output signals 345a, ..., 345n are transmitted to the third hardware component 322 and received by the third set of transceivers 352a, ..., 352n of the third hardware component 322. Hence, data is transmitted from the third hardware component 322 back to the third hardware component 322, while simultaneously performing the third mathematical operation on the data 344a, .... 344n. In the preceding examples, a single optical component performs the data processing on the data transported between the hardware components. However, the present disclosure is not limited thereto and the data can be processed by more than one optical component, or two or more subcomponents of an optical component. This allows multiple mathematical sub-operations (e.g. amounting to a resultant overall mathematical operation) to be carried out on the data during transport. For example, the optical apparatus 30 shown in Figure 3 further comprises a fourth hardware component 323. The fourth hardware component 323 is a separate and distinct component from the first, second, and third hardware components 320, 321,322. The fourth hardware component 323 described herein may relate to a first, second, third, ..., nth hardware component or may comprise a plurality of hardware components. The wording “fourth” hardware component is merely provided as a way of numbering the hardware components and this in no way limits the optical apparatus 30 to first, second, third, and fourth hardware components only. Any of the functions of any of the fourth hardware component described herein may be carried out by an nth hardware component. The fourth hardware component has its own network interface, thereby allowing it to be formed as part of a network including one or more of the first to third hardware components. The fourth network interface is different from the first, second and third network interface. The fourth network interface may have a fourth identifier different from the first, second and third identifier, wherein the fourth identifier may take the same format (but not necessarily the same identity) as the first, second and third identifiers, such as a MAC address. The fourth hardware component 323 may be separate or distinct from the first, second and third hardware components, e.g. communicatively isolated (except for through the optical apparatuses described herein) from or physically separate from the first, second and third hardware components as the first, second and third hardware components are separate or distinct from each other. The optical apparatus 30 shown in Figure 3 further comprises a fourth optical component 333 configured to receive first set of optical output signals 341a.....341 n as a fourth set of optical input signals 341a, .... 341 n transmitted by the first optical component 330. The fourth set of optical input signals 341a, ..., 341 n are processed by the fourth optical component 333 applying a fourth mathematical operation or function to produce at least one fourth optical output signal (e.g. a fourth set of optical output signals 346a, ..., 346n). The fourth set of optical output signals 346a, ..., 346n are transmitted to the fourth hardware component 323 and received by a second set of receivers 311a, ..., 311 n of the fourth hardware component 323. Hence, data is transmitted from the first hardware component 320 to the fourth hardware component 323 via the first and fourth optical components 330, 333, while simultaneously performing the first and fourth mathematical operations (e.g. sequentially) on the data 341a, ..., 341n, 340a, ..., 340n. An example of an optical component which can perform multiple sub-operations is a 4f OFT stage. In this case, the 4f OFT stage includes a first 2f OFT stage (e.g. in Figure 3, the first optical component 330) having two or more input channels (e.g. in Figure 3, those carrying the input signals 340a...340n) and two or more output channels (e.g. in Figure 3, those carrying the output signals 341a...341n). The 4f OFT stage also includes a second 2f OFT stage (e.g. in Figure 3, the fourth optical component) having two or more input channels (e.g. in Figure 3, those carrying the input signals 347a... 347n) and two or more output channels (e.g. in Figure 3, those carrying the output signals 346a...346n). The output channels of the first 2f OFT stage are connected to the input channels of the second 2f OFT stage. The “2f’ and “4f" processes carried out by the 2f stage and 4f stage, respectively, are so named due to their relation to a classical coherent optical processing system where a Fourier transform is defined as a “2f’ system by have an input function placed a distance “f” in front of a lens and the resulting interference pattern being captured at a distance “f behind the lens, consistent with a Fourier transform. In this case T relates to the focal length of the lens. In a “4T system there are two such stages with a multiplication stage between the two, such that an input function may be multiplied in Fourier space with another function before the product is inverse Fourier transformed at the rear focal plane of the second lens stage. However, the term 2f stage is used herein to refer to not only those classical systems but to also encompass any optical Fourier transform stage in which a single Fourier transform operation is performed (with or without a lens). Likewise, the 4f stage can include any two of such optical Fourier transform stages (with or without lenses). Examples of Fourier transform stages without a lens are described with reference to Figures 4a and 4b, for example. The first 2f stage performs an optical Fourier transform of the input function defined by the optical signal at the input channels of the first 2f stage. Then the second 2f stage performs an optical Fourier transform of an intermediate function defined by the optical signal at the input channels of the second 2f OFT stage. An intermediate mathematical sub-operation can occur between the two 2f OFT stages. For example, the optical signals in the output channels of the first 2f OFT stage can be multiplied before transmission to the input channels of the second 2f OFT stage. This amounts to multiplication in the Fourier space of the result of the first Fourier transform and then a second Fourier transform of the result of the multiplication. The resulting optical signals in the output channels of the second 2f OFT stage are received at the second hardware component. Thus, the data transported from the first to the second hardware component undergoes a first mathematical sub-operation (a Fourier transform), the result of the first mathematical sub-operation is multiplied in a second mathematical sub-operation and the result of the multiplication undergoes another Fourier transform in a third mathematical sub-operation. In more general terms, any one or more of the respective mathematical operations described herein can comprise a plurality of mathematical sub-operations, for example including a first sub-operation including a first Fourier transform, a second sub-operation including a multiplication (e.g. in Fourier space) of the result of the first sub-operation, and a third suboperation including a second Fourier transform of the result of the second sub-operation. Thus an optical convolution is performed by the 4f OFT stage. An example of such a combination of suboperations outside of the context of data transportation between hardware components is described in detail with reference to Figures 11 and 12 of WO2023 / 170405A1 the disclosure of which is incorporated herein by reference. The optical apparatus 30 further comprises a fifth optical component 334 configured to receive a fifth set of optical input signals 347a, ..., 347n transmitted by a second set of transmitters 301a, ..., 301 n of the fourth hardware component 323. The fifth set of optical input signals 347a, ..., 347n are processed by the fifth optical component 334 applying a fifth mathematical operation or function to produce at least one fifth optical output signal (e.g. a fifth set of optical output signals 348a, ..., 348n). The fifth set of optical output signals 348a, ..., 348n are transmitted to the first hardware component 320 and received by a third set of receivers 312a, ..., 312n of the first hardware component 320. Hence, data is transmitted from the fourth hardware component 323 to the first hardware component 320, while simultaneously performing the fifth mathematical operation on the data encoded onto the optical input signals 347a, ..., 347n. This is an example of an embodiment in which one hardware component (e.g. in Figure 3, the first hardware component) is connected so as to transmit data to another hardware component (e.g. in Figure 3, the second hardware component) and is also connected to receive data from and / or transmit data to yet another hardware component (e.g. in Figure 3, the fourth hardware component). The apparatus described with reference to Figures 1,2 and 3 can alternatively be described in general terms as a network comprising at least one optical transport link connecting network nodes of the network, wherein the at least one optical transport link includes an optical component arranged to perform a mathematical operation on data sent through the at least one optical transport link. In the example of Figures 1 and 2, a first node of the network nodes is associated with the first network interface and a second node of the network nodes is associated with the second network interface and the at least one optical transport link comprises a first optical transport link arranged to carry the first set of optical input signals and the at least one first optical output signal. In the example of Figure 3, a third node of the network nodes is associated with the third network interface, and the at least one optical transport link comprises a second optical transport link arranged to carry the set of optical input signals and the at least one optical output signal from the second hardware component to the third hardware component. In general, each hardware component comprises a transmitter arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component, and / or a receiver arranged to receive each respective optical output signal received at the respective hardware component, and / or a transceiver arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component and receive each respective optical output signal received at the respective hardware component. As described above, particularly useful forms of mathematical operation, Fourier transforms and convolutions, can be performed optically using an optical Fourier transform (OFT) device. According to the present disclosure, an OFT device can be used in the data transport path between the network interface of one hardware component and the network interface of another hardware component. A one-dimensional (1D) OFT device (such as an integrated photonics OFT device) can be realised in a two-dimensional structure, where the light is confined in one dimension and diffracts freely in the other two. In an example of such an OFT device, the input and output of the OFT device are arrays of input and output ports serving as the exit or entrance of waveguides or light channels. The light from each input port is diffracted into a wavefront wide enough to cover all output ports. At each output port, the contribution from each input port has the same intensity when the optical power at all the input ports is the same. The angle of the wavefront at the output array is determined by the angle of the input port, and sets the phase delay at each output port. One way to achieve this is to have the input and output arrays arranged on the arc of a different circle, on which lies the centre of the other circle. The Fourier transform of the input array forms on the line of the second circle. For a given radius of circle and number of input ports the angular spacing of the input and output arrays can be calculated so that the output ports sample a single order of the Fourier transform of the input data. The device will have some tolerance to how close the input and output ports need to be to the arc, with small changes in radial distance or lateral distance (but not angle) able to be compensated. If the radius is large enough, the arc can be approximated to a straight line. ‘Large enough’ means the distance between the arc and its tangent at the edge of the zero order FT is much less than a wavelength. Figure 4a shows a known 1D OFT device (or Fourier transform waveguide) 400 of this type. In brief summary, Figure 4a shows a Fourier Transform slab waveguide 400 where the light is constrained in one (cartesian) dimension (z) and diffracts freely in the other two dimensions (x and y). The OFT device includes a first array 410 of input ports 411, a second array 420 of output ports 421. The second array 420 of output ports is arranged along the Fourier plane of the Fourier transform waveguide. As will be understood by the skilled person, the Fourier plane may be a plane or a curved surface at which the Fourier transformation of the light at the input ports is formed. An interference region 430 is defined in the space or volume between the first array and second array, and may include an input coupling region connecting the first input array and the diffraction region and an output coupling region connecting the diffraction region and the second output array. The interference region 430 is surrounded in the x and y plane by a boundary 441. The boundary 441 may be directly adjacent the interference region 430 or there may be a spatial margin between at least some edges (perimeters) of the interference region 430 and the boundary 441. The interference region and any surrounding volume in which the light from the input ports propagates can be formed by etching or machining a block, slab or wafer of material to form the interference region and any surrounding volume within the boundary 441 (e.g. as a relief therein or as a standalone block or an embossed structure). The boundary 441 surrounding or adjacent the interference region 430 therefore includes sides (as in the minor faces of a three-dimensional slab). The interference region is constrained in the z-direction (as in the thickness direction of the slab) by faces (as in the major faces of the slab). The faces of the boundary surrounding or adjacent to the interference region 430 are exposed to the light emitted from the input ports. The slab waveguide is any photonic waveguide and may be realised using any of the following technology or combination of: • A slab waveguide in silicon-on-insulator (SOI) • A photonic crystal (PhC) with or without periodic defects or sub-wavelength holes • A slab waveguide in silicon nitride (SiN) • A waveguide on a compound photonic technology (lll-V or ll-VI) • Any plasmonic waveguide • A metasurface • Or another photonic technology In the interference region, there may be a void or, alternatively, a (for example, homogenous) medium, and / or a medium with uniform refractive index or engineered to have a uniform refractive index. The first array 410 is arranged on (or along) a first arc 410a of a first circle 410c and the second array 420 is arranged on (or along) a second arc 420a of a second circle 420c offset from the first circle. Preferably, the first circle 410c has a centre which lies on the second arc 420a and the second circle 420c has a centre which lies on the first arc 410a, Preferably, the centre of the first circle 410c lies at or near the centre of the second array 420 and the centre of the second circle 420c lies at or near the centre of the first array 410. The first arc 410a and second arc 420a respectively define a first portion 431a and second portion 431 b of the perimeter 431 of the interference region 430. A third portion 431c and fourth portion 431d of the perimeter 431 join respective ends (or edges) of the first portion 431a and second portion 431b. That is, the third portion 431c is a virtual face which extends in a plane between a first end of the first portion 431a and first end of the second portion 431b, and the fourth portion 431 d is a virtual face which extends in a straight line (or a plane) between a second end of the first portion 431a and second end of the second portion 431 b. The first to fourth portions 431 a-d constitute the whole of the perimeter 431 in the x-y plane (the plane in which the input and output ports are arranged). The input ports 411 are the exits (e.g. exit pupils or exit apertures) of input channels 401, which can also be described as waveguides or coupling structures. That is, the input ports can be connected to any of the following, or combination of: • Waveguides manufactured using the same technology, methods and / or materials as the free space Fourier Transform slab waveguide region • Coupling structures such as grating couplers or edge couplers, that couple in light from an external source • Coupling structures such as tapered couplers, that couple in light between vertically displaced waveguides (i.e. waveguides in a silicon layer coupling light into a SiN Fourier Transform slab waveguide region). • Impedance matching structures that reduce the reflection between the free space Fourier Transform slab waveguide and any of the above. Embodiments can be used with existing photonic technology. For example, both the phase and amplitude of light in input channels 401 connected to the input ports 411 can be controlled or modulated using a transmitter in the input channel. The term transmitter when used throughout this disclosure can be any photonic modulator. It can encompass a light source or emitter (provided that it is coherent and each transmitter has some detectable or controllable phase relationship to other transmitters in the OFT apparatus); a transmitter arranged to control the transmission of (coherent) light from a light source; a modulator arranged to modulate (coherent) light from a light source; or an encoder arranged to encode a signal onto a (coherent) optical signal. That is, the transmitter can be an optical light transmitter, optical encoder, photoemitter or photo modulator, including, by way of non-limiting example, the following or a combination of: • Mach Zehnder Modulators • PN modulators • Ring modulators • Thermal modulators • Another photonic integrated circuit arranged to modulate an optical input signal. The term transmitter also encompasses any of the optical encoders described with reference to Figures 2, 3a, 3b, 4a-g, 5a-f, 6a-e, 7a and 7b of W02023170405(A1), the disclosure of which is hereby incorporated by reference. Protection is sought for an OFT apparatus as described herein and including such optical encoders, though the present disclosure is not limited to these types of transmitters. The output ports 421 can be placed to sample one or more orders of the Fourier transform of the input data either as a fast Fourier transform or otherwise. Generally, the output ports are positioned to capture or sample the zero-order Fourier transform; however, in some embodiments, output ports may alternatively or in addition be positioned to capture or sample higher order Fourier transform modes, such as the first or second order. Embodiments are directed to sampling a Fast Fourier Transform. If sampling a Fast Fourier Transform, the number of output ports used to extract data must be at least the same as the number of input ports. The maximum number of data points is the same as the number of input ports i.e. additional ports can be used to extract other orders of the Fourier transform but the extra ports will contain copies of the zero-order data and no additional information. The number of input ports 411 can be two or more up to sixteen. As will be described with reference to Figure 4b, the number of input ports in a particularly advantageous arrangement is four. In operation, the Fourier Transform slab waveguide is illuminated with modulated or unmodulated light at one or more of the input ports 411. In more detail, a light source, e.g. a solid-state semiconductor laser source (not shown), provides coherent light. The light source can be housed off-chip, in which case the light is coupled into the OFT device using a fibre and coupling said fibre via grating couplers, or edge couplers using ferrules, or V-shaped grooves. Alternatively, the light source can be packaged in the same carrier substrate with the OFT device and light coupled into the OFT device through edge couplers and photonic wire bonds. Alternatively, the light source can be integrated with the OFT device and light coupled into the OFT device through edge couplers and tapers with or without photonic wire bonds. Coherent light from the light source is amplified using an optical amplifier (not shown) before being split into the plurality of input channels 401. This is achieved by either splitting coherent light from the light source off-chip and coupling in light to fibre bundles which feed the input channels or act as the input channels themselves, or using a fibre splitter, or by coupling in the light to a single channel initially, and splitting the light into input streams using cascaded MMIs or Y-branches. If using cascaded MMIs or Y-branches the input streams stem from the output of the last stacked or cascaded 1x2 splitters. The input channels 401 carry the input streams of light split from the light source to the input ports 411. The inserted modulated or unmodulated light undergoes diffraction within the interference region 430. The output ports 421 are placed on the Fourier plane, i.e. where the diffracted light forms the optical Fourier transform of the light pattern from the input ports 411. The input ports 411 bring light into the interference region 430. The light at an input port 411 has information encoded into the phase and / or amplitude of the field. The size and shape of the optical field contained within each input port 411 to the free space Fourier transform slab waveguide will define the envelope function of the Fourier transform according to the convolution theorem. The output ports 421 are placed in the Fourier plane (which lies along the second arc 420a). Light arrives at the output ports 421 as a set of waves at a range of angles which match the relative positions of the input ports 411. The waves from all input ports 411 sum (e.g., coherently) to form an analogue Fourier transform. The Fourier transform in the Fourier (or output) plane (which lies along the second arc 420a) contains the full Fourier transform of the light pattern at the input plane (which lies along the first arc 410a), including the input mode shape and input envelope function. The FT is sampled for detection by the output ports 421, and then the detection method will determine if the solution to the Fourier Transform is analogue or digital. Light collected by the output ports 421 and channelled through the output channels connected to the output ports is detected typically using at least one receiver. The term ‘receiver’ when used throughout the present disclosure includes any component arranged to detect the parameters of an optical signal, in particular relative or absolute amplitude (intensity), relative or absolute phase, or both. That is, the term receiver means an optical receiver. The receiver can be analogue (connected to an analogue-to-digital converter, ADC) or digital. A receiver can include one or more (e.g. a pair of) photodiodes and said light is either detected on a single photodiode per channel or the signal is mixed with a reference beam for homodyne detection. The receiver can be a coherent detector with 90° optical hybrid for detecting the phase of the optical signal. PINs or Avalanche Photo Diodes may be used with trans impedance amplifiers. The receivers that are used to extract data for detection may preserve the amplitude of the Fourier transform, and the phase if the phase is being detected. The term receiver also encompasses any of the balanced detectors or combinations thereof described with reference to Figure 8a or 8b of W02023170405(A1), the disclosure of which is hereby incorporated by reference. Protection is sought for an OFT apparatus as described herein and including such balanced detector arrangements, and the associated methods of operating such an OFT apparatus, though the present disclosure is not limited to these types of receivers. In addition to the first arc 410a and the second arc 420a, the waveguide shown in Figure 4a comprises boundaries adjacent to, and outside of, the third portion 431c and fourth portion 431 d of the perimeter 431 interference region 430. In particular, the waveguide of Figure 4a comprises a first waveguide boundary 441 a and a second waveguide boundary 441 b. The first waveguide boundary 441 a is a planar surface extending between a first end of the first arc 410a and a first end of the second arc 420a. The second waveguide boundary 441b is a planar surface extending between a second end of the first arc 410a and a second end of the second arc 420a. The first and second waveguide boundaries 441a, 441 b may take other forms other than planar boundaries. For example, the first and second waveguide boundaries can be shaped, angled or otherwise configured to absorb or redirect stray light passing through the virtual planes 431c, 431 d so that it does not reflect back into the interference region 430. The interference region 430 is positioned between the input ports 411 (i.e. at the input plane of the OFT device) and the output ports 421 (i.e. at the output or Fourier plane of the OFT device). In the interference region 430, the light from the individual input ports interferes to produce a diffraction pattern. The output ports 421 are positioned to capture the diffraction pattern at the Fourier plane (though a diffraction pattern will be present throughout the interference region). Each output port 421 is connected via an output channel 402 to an optical amplifier (not shown) and then on to a detector (which may also be described as a receiver or decoder). Each optical amplifier is arranged to amplify the respective output stream. The optical amplifiers may be semiconductor optical amplifiers (SOAs). However, embodiments are not limited thereto, and other types of optical amplifier may be used. Alternatively, no optical amplifiers are used. The value of a first complex element encoded onto each of the input streams emerging from the input ports 411 can differ between input streams so that the value of the input function varies with the positions of the input ports in the first array due to the spatial variations in the input function. Two variables can be used to define or approximate each of the input and output functions: (i) the relative position of the ports within the array; and (ii) the value of the complex number encoded onto the streams of light passing through (e.g. entering or exiting) the ports. It may therefore be understood that the input and output functions are each sampled versions of a continuous function, wherein the sampling resolution is determined by the aperture size of the ports and / or the port spacing or pitch. Temporal variation in the input streams can also be applied by varying the value of the first complex element encoded onto each input stream overtime. The input streams may be continuous (always on, or on for multiple cycles of a clock signal). Alternatively, the input streams may also be pulsed (intermittently on and off, optionally in sync with a clock signal). The value of the first complex elements encoded onto the input streams may change with each clock cycle so that multiple optical Fourier transforms can be carried out consecutively, frame-by-frame. The detector (or receiver or decoder) is arranged to detect (or decode) a second complex element encoded onto each output stream collected by the output ports 421. The terms ‘input stream’ and ‘input signal’ are used interchangeably in the present disclosure. Likewise, the terms ‘output stream’ and ‘output signal’ are used interchangeably in the present disclosure. Input streams may be carried by input channels and output streams by output channels described in the present disclosure. The decoder is arranged to decode a second complex element from each of the output streams based on at least one characteristic of the respective output stream. A value of the at least one characteristic is detected by the decoder and translated into a form which is representative of the second complex element. In embodiments, the at least one characteristic is a phase and / or amplitude of the output stream and the value of said phase and / or amplitude is equal to or correlates with the value of the second complex element. The phase may be a phase relative to the phase of the input streams at the input ports 411. The OFT apparatus (or OFT device) can be any optical apparatus capable of performing an optical Fourier transform of an input optical field delivered via two or more input channels and received at a corresponding number of output channels. This can take the form of a waveguide array including N input channels, the output of which is split into N mixing channels, nth mixing channels from each input channel are then joined to form K output channels. However, a more efficient arrangement is a free-space OFT apparatus (such as described with reference to Figures 4a and 4b) in which N input channels deliver light into a free space region which allows the light from the input channels to diffract and create an interference pattern at K output channels. N is an integer of at least 2, optionally an integer multiple of 2 or 4, optionally 4. K is at least equal to N. Examples of an OFT apparatus are described with reference to Figures 1a, 1b and 2, though the present disclosure is not limited to these examples. For an input vector comprising the frame of input states simultaneously present at the input channels, the full discrete optical Fourier transform of the frame of input states is derivable from the output states detected at all output channels. In this sense, the OFT apparatus is arranged to perform a discrete Fourier transform. The discrete Fourier transform satisfies equation 1: .271. Xk = 2n=o xn.e lNkn (Equation 1) where k is the index of output channel, Xk is the channel k output, n is the index of input channel, xn is the channel n input, N is the number of input channels. Figure 4b shows a special form of the 1D OFT device described with reference to Figure 4a. In Figure 4b, each of the input ports are arranged on a first circular arc and each of the output ports are arranged on a second circular arc. The distance between the first and second circular arcs is equal to the radius of the first circular arc and also equal to the radius of the second circular arc. The input ports are arranged at angles 0n from a zeroth position on the second arc and the output ports are arranged at angles 9n from a zeroth position on the first arc. The zeroth position on the first arc is directly opposite the zeroth position on the second arc with respect to a virtual line bisecting the common radius of the first arc and second arc. That is, the zeroth position on the first arc and the zeroth position on the second arc lie at opposite ends of the common radius of the first arc and second arc. The angles 9n are defined by equation 2: f)n = sin1 (n J— (Equation 2) wherein n is the port number, N is the total number of input ports or output ports, R is the radius and neffis the effective index of the waveguide mode. In Figure 4b, the port number n starts at -(1^2)+1 if N is even and -((N-1)}2 if N is odd at the lowest port, and increases in integers up to the top. The effective index of the waveguide mode neff describes the characteristics of guiding mode propagation in the OFT device and can be determined using methods known to those skilled in the art from the optical properties of the materials used to construct the waveguide and the dimensions of the waveguide. The OFT device of embodiments can also take other forms other than that described with reference to Figure 4b. Embodiments include any OFT device capable of preforming a discrete Fourier transform optically. Such OFT devices satisfy the discrete Fourier transform equation (equation 1). Figure 5 shows an optical circuit diagram for an OFT apparatus such as those described with reference to Figures 4a or 4b. The OFT apparatus includes an OFT stage 510 having input channels 501 and output channels 502, a grating coupler 503, a source channel 511, splitters 520, combiners 530, transmitters (including modulators or encoders) 540, input channel phase controls 542, monitor channel receivers 560, monitor channel phase controls 565, output channel receivers 570, reference channel phase controls 580, reference channels 581, a reference source channel 582, and a reference channel amplifier 590. The grating coupler 503 provides an inlet for a light source (e.g. laser) such as that described with reference to Figure 4a. The input channels 501 are branched off from a single source channel 511 using a series of cascaded splitters 520 and extend to the OFT apparatus. A transmitter (or encoder) 540 is provided in-line in each input channel. A splitter 520 is provided to separate a portion of the optical input signal from the transmitter 540 via a monitor channel 561 before the transmitter signal reaches the OFT device 510. A combiner 530 combines the optical input signal from the monitor channel 561 with an optical perturbation signal provided via a perturbation channel 562 and feeds the combined signal to the monitor channel receiver 560. The perturbation channel 562 includes one of the monitor phase controls 565. Each output channel 502 is connected between the OFT stage 510 and a combiner 530 which combines the optical output signal from a corresponding output channel 502 with an optical reference signal from a corresponding reference channel 581 and feeds the combined optical signal into a corresponding output channel receiver 570. Each reference channel 581 includes a reference channel phase control 580. The reference channels 581 are connected via series of cascaded splitters 520 to the reference source channel 582. Each transmitter or encoder 540 includes a modulator 541 and an input channel phase control 542. In the example of Figure 5 the modulator 541 is a modulator pair and the phase control 542 is a phase control pair on separate parallel branches of the input channel 501. In other examples, the input channel phase control 542 is a single-phase control provided in the input channel downstream of the transmitter. In operation, the modulator 541 in each input channel 501 modulates light from the light source to provide the optical input signal having an input state to the OFT stage 510. The phase control 542 adjusts the input state. The phase of the light in the perturbation channel 562 is controlled by the monitor phase control 565 to produce the optical perturbation signal. The monitor channel receiver 560 detects the state of the combined optical input signal and optical perturbation signal, or just the input state if there is no perturbation light provided in the perturbation channel. The output channels each carry the optical output signal in a corresponding output state from the OFT stage 510. The OFT stage can take the form of the OFT device described with reference to Figures 4a and 4b. The phase of the light in the reference channels 581 is controlled by the reference channel phase controls 580 to produce the optical reference signal. The reference channel amplifier 590 controls the amplitude and / or phase of the optical reference signal. The output channel receiver 570 detects the state of the combined optical output signal and optical reference signal, or just the output state if the optical reference signal is switched off by the reference channel amplifier 590. The term ‘state’ (e.g. input state or output state) as used in the present disclosure refers to a parameter or parameters of an optical signal, or the representation of the parameters) in digital or numerical form. The state may be understood to be or represent a value or a level. The parameter may include amplitude or intensity of the signal or may be phase or relative phase of the signal. The digital or numerical form may be a complex number, or a signed or unsigned real or imaginary number, or a (bit) representation thereof. In one implementation of an apparatus according to the present disclosure, the apparatus comprises a first optical component (for example the OFT device of Figure 4a, or the OFT stage 510 of Figure 5) arranged to perform a first mathematical operation (for example a Fourier transform or convolution) on a first set of optical input signals (for example those encoded by transmitters 540 of Figure 5). The first optical component performs the mathematical operation by transforming the first set of optical input signals to produce at least one first optical output signal (for example the signals decoded by receivers 570 of Figure 5). The at least one first optical output signal is different from the first set of optical input signals in that, in the example of Figure 5, it is a set of signals representing a function which is the Fourier transform of the function represented by the first set of optical input signals. The apparatus comprises a first hardware component (for example in Figure 5, the first hardware component 120 including the transmitters 540) configured to transmit the first set of optical input signals to the first optical component (in the example of Figure 5, the OFT device 510) via input channels (e.g. in Figure 5, the input channels 501). The apparatus further comprises a second hardware component (for example in Figure 5, the second hardware component 121 including the receivers 570). The second hardware component is configured to receive the at least one first optical output signal from the first optical component (in the example of Figure 5, this is via the output channels 502). The first hardware component includes a first network interface (for example connected to or associated with the transmitters 540 in the example of Figure 5) and the second hardware component includes a second network interface (for example connected to or associated with the receivers 570 in the example of Figure 5). The hardware components described herein, such as those described with reference to Figures 1-5, can include one or more of: an integrated circuit, ‘IC’, chiplet; a network on chip, ‘NOC’; a system on chip, ‘SoC’; a multi-chip module, ‘MCM’; a memory module; a graphics processing unit, ‘GPU’; a tensor processing unit, ‘TPU’; a server blade; a motherboard; a disaggregated node; a high bandwidth memory, ‘HBM’; a sensor; an actuator; a data transmitter; and a receiver, or any combination of the above. In an embodiment multiple hardware components are connected, and the apparatus 30 can perform a butterfly transposition over the PHY layer between transmitters, receivers, and / or transceivers using integrated photonic waveguides or optical fibers for physical propagation. Any combination of operations is possible through each hardware component and optical component and the present disclosure is not limited to the specific examples described above. The apparatuses 10, 20, 30 described with reference to Figures 1,2 and 3, respectively, may be implemented on at least one photonic interposer, chip, photonic substrate, photonic transmitter, or OFT device using integrated photonic waveguides or optical fibers for physical propagation of data carrying light between photonic modules. A photonic waveguide arrangement may be positioned at or within a boundary between a pair of adjacent photonic modules to build a photonic network using the space between the photonic modules. The input channels of the present disclosure may use at least two photonic waveguides and the output channels may use at least one photonic waveguide when there is only one output channel. Hence, at least two photonic waveguides are implemented (or etched) between each pair of adjacent photonic modules to accommodate the input channels. The photonic network comprises a plurality of optical switches formed on the apparatus or photonic substrate to enable each hardware component to either transmit or receive data depending on the configuration of transmitters, receivers, and transceivers. Optical switches allow a dynamic butterfly transposition over the PHY layer as data can be transferred to different optical and hardware components throughout the photonic network. In some embodiments, the photonic waveguides (input and output channels) may be in a different layer of optical transmission, and optionally, the photonic waveguides are in a layer above the hardware components. In this case, a photonic bridge may be used to optically couple the photonic waveguides. The optical components may be within the photonic waveguides or the photonic bridge to enable parallelisation of data transmission and computation on the PHY layer. A method of operating any apparatus 10, 20, 30 described herein comprises transmitting, by a first hardware component, a first set of optical input signals to a first optical component of the apparatus, performing, by the first optical component, a first mathematical operation on the first set of optical input signals by transforming the first set of optical input signals to produce at least one first optical output signal different from the first set of optical input signals, and receiving, by a second hardware component, the at least one first optical output signal from the first optical component, wherein the first and second hardware components are separate components. In alternative embodiments, the optical components arranged to perform mathematical operations described in the present disclosure can be replaced by digital (electronic) processing components or quantum computing processors arranged to perform the same mathematical operations. In this case, the optical transmitters, receivers and the optical channels linking them to the component performing the mathematical operation can be replaced by electronic components, for example purely electronic encoders and decoders for the transmitters and receivers, respectively, and wires or cables for the various input and output channels. The input and output signals in these embodiments are electronic signals. It will be appreciated by those skilled in the art that various modifications and alterations could be made to disclosure above without departing from the concepts defined in the appended claims. Some implementations have been discussed above and others will be apparent to those skilled in the art. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications and variants within the scope of the appended claims. Also described herein are the following numbered items: Item 1. An apparatus comprising: a first component arranged to perform a first mathematical operation on a first set of input signals by transforming the first set of input signals to produce at least one first output signal different from the first set of input signals; a first hardware component configured to transmit the first set of input signals to the first component; and a second hardware component con figured to receive the at least one first output signal from the first component, wherein the first hardware component includes a first network interface and the second hardware component includes a second network interface. Item 2. The apparatus of item 1, wherein the first network interface has a first identifier and the second network interface has a second identifier different from the first identifier. Item 3. The apparatus of item 1 or 2, wherein the first hardware component comprises at least one electronic circuit configured to provide data to be encoded onto the first set of input signals and the second hardware component comprises at least one electronic circuit configured to receive data decoded from the at least one first output signal. Item 4. The apparatus of any preceding item, wherein the first hardware component is electronically isolated from the second hardware component other than via the first component. Item 5. The apparatus of any preceding item, wherein the at least one first output signal comprises a first set of output signals. Item 6. The apparatus of any preceding item, wherein the first hardware component has a first MAC address and the second hardware component has a second MAC address different from the first MAC address. Item 7. The apparatus of any preceding item, wherein the first mathematical operation comprises one or more of the following: addition, subtraction, multiplication, Fourier transform, or convolution. Item 8. The apparatus of item 7, wherein any one or more of the respective mathematical operations comprises a plurality of mathematical sub-operations, optionally including a first sub-operation including a first Fourier transform, a second suboperation including a multiplication (e.g. in Fourier space) of the result of the first sub-operation, and a third sub-operation including a second Fourier transform of the result of the second sub-operation. Item 9. The apparatus of any preceding item, wherein each respective hardware component comprises one or more of: an integrated circuit, ‘IC’, chiplet; a network on chip, ‘NOC’; a system on chip, ‘SoC’; a multi-chip module, ‘MCM’; a memory module; a graphics processing unit, ‘GPU’; a tensor processing unit, ‘TPU’; a server blade; a motherboard; a disaggregated node; a high bandwidth memory, ‘HBM’; a sensor; an actuator; a data transmitter; and a receiver. Item 10. The apparatus of any preceding item, further comprising: an input channel arranged to carry each respective input signal; and an output channel arranged to carry each respective output signal. Item 11. The apparatus of any preceding item, wherein, the apparatus further comprises one or more of: a Fourier Transform stage; a combiner; a phase shifter; a waveguide; and an intensity modulator. Item 12. The apparatus of any preceding item, wherein the respective hardware components are arranged to simultaneously transmit each input signal of the respective set of input signals to respective components, and wherein the respective hardware components are arranged to simultaneously receive each output signal of the respective at least one output signals from respective components. Item 13. The apparatus of any preceding item, wherein the respective hardware components are arranged to be separated from one another by a distance of at least 1mm, optionally at least 5mm, at least 10mm, at least 25mm, at least 50mm, or at least 100mm, or at least 500m., or at least 2km, or at least 10km. Item 14. The apparatus of any preceding item, wherein the input and output signals are optical signals or electronic signals, and / or any of the respective components arranged to perform a mathematical operation are optical components, electronic components, digital processing components or quantum-based processing components. Item 15. The apparatus of any preceding item, further comprising a third hardware component, wherein the third hardware component includes a third network interface, and / or wherein the third hardware component is different from the second network interface, and / or wherein the third hardware component is electronically isolated from one or both of the first and second hardware components, and / or wherein the third network interface has a third identifier different from the first identifier and second identifier. Item 16. The apparatus of any preceding item, further comprising a second component arranged to perform a second mathematical operation on a second set of input signals by transforming the second set of input signals to produce at least one second output signal different from the second set of input signals. Item 17. The apparatus of item 16, wherein the at least one second output signal comprises a second set of output signals. Item 18. The apparatus of item 17, wherein: the first hardware component is further configured to transmit the second set of input signals to the second component, and / or the second hardware component is further configured to transmit the second set of input signals to the second component, and / or when dependent on item 16, the third hardware component is configured to transmit the second set of input signals to the second component. Item 19. The apparatus of item 17 or 18, wherein: the first hardware component is further configured to receive the at least one second output signal from the second component, and / or the second hardware component is further configured to receive the at least one second output signal from the second component, and / or when dependent on item 16, the third hardware component is configured to receive the at least one second output signal from the second component. Item 20. The apparatus of any of items 16 to 19, further comprising a third component arranged to perform a third mathematical operation on the first set of output signals by transforming the first set of output signals to produce at least one third output signal different from the first set of output signals. Item 21. The apparatus of item 20, wherein the at least one third output signal comprises a third set of output signals. Item 22. The apparatus of item 21, wherein the first component is further configured to transmit the first set of output signals to the third component. Item 23. The apparatus of item 21 or 22, wherein: the second hardware component is further configured to receive the at least one third output signal from the third component, or, when dependent on item 16, the third hardware component is configured to receive the at least one third output signal from the third component. Item 24. The apparatus of any preceding item, wherein the second hardware component is further configured to transmit a fourth set of input signals to the first component and the first hardware component is configured to receive at least one fourth output signal from the first component, optionally wherein the at least one fourth output signal comprises a fourth set of output signals. Item 25. The apparatus of item 15 or any of items 16 to 24 when dependent on item 15, wherein the third hardware component is configured to receive the at least one first output signal from the first component. Item 26. The apparatus of any preceding item, wherein each hardware component comprises: a transmitter arranged to transmit each respective input signal transmitted by the respective hardware component to the respective component; and / or a receiver arranged to receive each respective output signal received at the respective hardware component, and / or a transceiver arranged to transmit each respective input signal transmitted by the respective hardware component to the respective component and to receive each respective output signal received at the respective hardware component. Item 27. A network comprising at least one transport link connecting network nodes of the network, wherein the at least one transport link includes a component arranged to perform a mathematical operation on data sent through the at least one transport link. Item 28. The network of item 27 comprising the apparatus of any of items 1-26, wherein a first node of the network nodes is associated with the first network interface and a second node of the network nodes is associated with the second network interface, and the at least one transport link comprises a first transport link arranged to carry the first set of input signals and the at least one first output signal. Item 29. The network of item 28 when dependent on any one of items 17-26, wherein a third node of the network nodes is associated with the third network interface, and the at least one transport link comprises a second transport link arranged to carry the second set of input signals and the at least one second output signal. Item 30. A method of operating an apparatus: transmitting, by a first hardware component, a first set of input signals to a first component of the apparatus; performing, by the first component, a first mathematical operation on the first set of input signals by transforming the first set of input signals to produce at least one first output signal different 5 from the first set of input signals; and receiving, by a second hardware component, the at least one first output signal from the first component, wherein the first hardware component includes a first network interface and the second hardware component includes a second network interface.

Claims

1. An apparatus comprising:a first optical component arranged to perform a first mathematical operation on a first set of optical input signals by transforming the first set of optical input signals to produce at least one first optical output signal different from the first set of optical input signals;a first hardware component configured to transmit the first set of optical input signals to the first optical component; anda second hardware component configured to receive the at least one first optical output signal from the first optical component,wherein the first hardware component includes a first network interface and the second hardware component includes a second network interface.

2. The apparatus of claim 1, wherein the first network interface has a first identifier and the second network interface has a second identifier different from the first identifier.

3. The apparatus of claim 1 or 2, wherein the first hardware component comprises at least one electronic circuit configured to provide data to be encoded onto the first set of optical input signals and the second hardware component comprises at least one electronic circuit configured to receive data decoded from the at least one first optical output signal.

4. The apparatus of any preceding claim, wherein the first hardware component is electronically isolated from the second hardware component.

5. The apparatus of any preceding claim, wherein the at least one first optical output signal comprises a first set of optical output signals.

6. The apparatus of any preceding claim, wherein the first hardware component has a first MAC address and the second hardware component has a second MAC address different from the first MAC address.

7. The apparatus of any preceding claim, wherein the first mathematical operation comprises one or more of the following:addition,subtraction,multiplication,Fourier transform, orconvolution.

8. The apparatus of claim 7, wherein any one or more of the respective mathematical operations comprises a plurality of mathematical sub-operations,optionally including a first sub-operation including a first Fourier transform, a second suboperation including a multiplication of the result of the first sub-operation, and a third sub-operation including a second Fourier transform of the result of the second sub-operation.

9. The apparatus of any preceding claim, wherein each respective hardware component comprises one or more of:an integrated circuit, ‘IC’, chiplet;a network on chip, ‘NOC’;a system on chip, ‘SoC’;a multi-chip module, ‘MCM’;a memory module;a graphics processing unit, ‘GPU’;a tensor processing unit, ‘TPU’;a server blade;a motherboard;a disaggregated node;a high bandwidth memory, ‘HBM’;a sensor;an actuator;a data transmitter; anda receiver.

10. The apparatus of any preceding claim, further comprising:an input channel arranged to carry each respective optical input signal; and an output channel arranged to carry each respective optical output signal.

11. The apparatus of any preceding claim, wherein, the apparatus further comprises one or more of:an optical Fourier Transform ‘OFT’ stage;a combiner;a phase shifter;a waveguide; andan intensity modulator.

12. The apparatus of any preceding claim, wherein the respective hardware components are arranged to simultaneously transmit each optical input signal of the respective set of optical input signals to respective optical components, and wherein the respective hardware components arearranged to simultaneously receive each optical output signal of the respective at least one optical output signals from respective optical components.

13. The apparatus of any preceding claim, wherein the respective hardware components are arranged to be separated from one another by a distance of at least 1mm, optionally at least 5mm, at least 10mm, at least 25mm, at least 50mm, or at least 100mm, or at least 500m., or at least 2km, or at least 10km.

14. The apparatus of any preceding claim, wherein the optical input and output signals are monochromatic.

15. The apparatus of any preceding claim, further comprising a third hardware component, wherein the third hardware component includes a third network interface, and / or wherein the third hardware component is different from the second network interface, and / or wherein the third hardware component is electronically isolated from one or both of the first and second hardware components, and / or wherein the third network interface has a third identifier different from the first identifier and second identifier.

16. The apparatus of any preceding claim, further comprising a second optical component arranged to perform a second mathematical operation on a second set of optical input signals by transforming the second set of optical input signals to produce at least one second optical output signal different from the second set of optical input signals.

17. The apparatus of claim 16, wherein the at least one second optical output signal comprises asecond set of optical output signals.

18. The apparatus of claim 17, wherein:the first hardware component is further configured to transmit the second set of optical input signals to the second optical component, and / orthe second hardware component is further configured to transmit the second set of optical input signals to the second optical component, and / orwhen dependent on claim 16, the third hardware component is configured to transmit the second set of optical input signals to the second optical component.

19. The apparatus of claim 17 or 18, wherein:the first hardware component is further configured to receive the at least one second optical output signal from the second optical component, and / orthe second hardware component is further configured to receive the at least one second optical output signal from the second optical component, and / orwhen dependent on claim 16, the third hardware component is configured to receive the at least one second optical output signal from the second optical component.

20. The apparatus of any of claims 16 to 19, further comprising a third optical component arranged to perform a third mathematical operation on the first set of optical output signals by transforming the first set of optical output signals to produce at least one third optical output signal different from the first set of optical output signals.

21. The apparatus of claim 20, wherein the at least one third optical output signal comprises a third set of optical output signals.

22. The apparatus of claim 21, wherein the first optical component is further configured to transmit the first set of optical output signals to the third optical component.

23. The apparatus of claim 21 or 22, wherein:the second hardware component is further configured to receive the at least one third optical output signal from the third optical component, or,when dependent on claim 16, the third hardware component is configured to receive the at least one third optical output signal from the third optical component.

24. The apparatus of any preceding claim, wherein the second hardware component is further configured to transmit a fourth set of optical input signals to the first optical component and the first hardware component is configured to receive at least one fourth optical output signal from the first optical component, optionally wherein the at least one fourth optical output signal comprises a fourth set of optical output signals.

25. The apparatus of claim 15 or any of claims 16 to 24 when dependent on claim 15, wherein the third hardware component is configured to receive the at least one first optical output signal from the first optical component.

26. The apparatus of any preceding claim, wherein each hardware component comprises: a transmitter arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component; and / ora receiver arranged to receive each respective optical output signal received at the respective hardware component, and / ora transceiver arranged to transmit each respective optical input signal transmitted by the respective hardware component to the respective optical component and to receive each respective optical output signal received at the respective hardware component.

27. A network comprising at least one optical transport link connecting network nodes of the network, wherein the at least one optical transport link includes an optical component arranged to perform a mathematical operation on data sent through the at least one optical transport link.

28. The network of claim 27 comprising the apparatus of any of claims 1-26, wherein a first node of the network nodes is associated with the first network interface and a second node of the network nodes is associated with the second network interface, andthe at least one optical transport link comprises a first optical transport link arranged to carry the first set of optical input signals and the at least one first optical output signal.

29. The network of claim 28 when dependent on any one of claims 17-26, wherein a third node of the network nodes is associated with the third network interface, andthe at least one optical transport link comprises a second optical transport link arranged to carry the second set of optical input signals and the at least one second optical output signal.

30. A method of operating an apparatus:transmitting, by a first hardware component, a first set of optical input signals to a first optical component of the apparatus;performing, by the first optical component, a first mathematical operation on the first set of optical input signals by transforming the first set of optical input signals to produce at least one first optical output signal different from the first set of optical input signals; andreceiving, by a second hardware component, the at least one first optical output signal from the first optical component,wherein the first hardware component includes a first network interface and the second hardware component includes a second network interface.

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