Methods and apparatus relating to optical switching

Abstract

Aspects of the present invention relate to optical switches, methods of operating optical switches, and systems including optical switches. The optical switch includes an input for receiving an optical data input and an optical address input. The optical switch further includes an output for outputting an optical data output. The optical switch additionally includes a first nonlinear optical medium, the first nonlinear optical medium being arranged to combine the optical data input and the optical address input to generate the optical data output. The frequency of the optical data output depends on the frequency of the optical data input and the frequency of the optical address input.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Aspects of the invention relate to optical switches, methods of operating optical switches, and systems including optical switches. [Background technology]

[0002] Data centers often use data networks to communicate between multiple interconnected server computers, known as nodes. Each node has a unique address, and network switches, such as Layer 2 network switches, can route data from a first node to an intended receiving node.

[0003] Generally, a network switch is an electronic switch. Commercial Layer 2 network switches typically have the capacity to accommodate approximately 50 nodes in a network. Therefore, data centers with a large number of nodes use various types of architectures to connect more nodes than can be supported by an individual network switch. An average data center carries data from over 40,000 nodes, requiring a large number of network switches to route the data. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention was conceived against this background. [Means for solving the problem]

[0005] In one aspect, the optical switch includes an input for receiving an optical data input and an optical address input. The optical switch further includes an output for outputting an optical data output. The optical switch additionally includes a first nonlinear optical medium configured to combine the optical data input and the optical address input to generate the optical data output. The frequency of the optical data output depends on the frequency of the optical data input and the frequency of the optical address input.

[0006] Advantageously, the use of nonlinear optical media allows logical operations to be performed entirely within the optical domain.

[0007] Even more advantageously, performing logical operations in the optical domain results in optical switches that consume less power and have faster switching capabilities than current prior art electronic switches, which allows for maximizing the data throughput of the optical switch.

[0008] Each switching operation performed within an electronic network switch requires an electronic logic operation to properly route data to the intended node. This logic operation introduces both latency and power consumption within the network switch. The average data center pushes data from 40,000 nodes at approximately 25 Gb / s per network connection, and Layer 2 electronic switches are estimated to account for 20% of the data center's power consumption. Furthermore, data centers themselves account for approximately 3.7% of global carbon emissions, and this number is increasing annually. With data generation estimated to increase at a rate of 97 to 181 zettabytes between 2022 and 2025, scaling up data centers is unsustainable amid global efforts to reduce carbon emissions.

[0009] While optical transceivers can be used to transmit data optically at very high speeds, current technology requires that the switching operations themselves be performed in the electronic domain, as they require electronic logic operations. Therefore, power consumption is still required to perform the electronic switching operations, and additional power is consumed in converting the transmitted data between electronic and optical transmission means.

[0010] In an all-optical switch according to the present invention, no electronic logic circuitry is used during data transmission between nodes. Instead, logic operations are performed entirely in the optical domain. Optical switches require less power than electronic switches because they do not need to power the electronic logic operations or convert data between electronic and optical transmission means.

[0011] Furthermore, current optical transceivers can transmit data at extremely high bandwidths, up to 400 Gb / s per serial channel. However, switching capacity remains limited by the 25 Gb / s per port performance of prior art electronic switches. Therefore, the per-port switching capacity is limited from a 400 Gb / s transmission link to 25 Gb / s at the switch, preventing the network from operating at its maximum speed. Electronic switches therefore incur delays due to the logical operations performed to route and switch data. In contrast, the passive nature of the all-optical switch of the present invention places no limit on the throughput of the optical switch. Therefore, the optical switch can accommodate all data transmission rates, eliminating bottlenecks at the switch and delays due to the execution of logical operations. Data can be transmitted through the optical switch at data transmission rates, e.g., 400 Gb / s. This data throughput is 15 times higher than what is currently achievable using prior art electronic switches.

[0012] In one embodiment, the inputs of the optical switch include a data input for receiving an optical data input and an address input for receiving an optical address input.

[0013] In one embodiment, the frequency of the optical data output depends on an arithmetic operation of the frequency of the optical data input and the frequency of the optical address input, which may be an addition of the frequency of the optical data input and the frequency of the optical address input.

[0014] Advantageously, manipulating optical signals input to a nonlinear optical medium in this manner allows logical operations to be performed entirely within the optical domain. There is no need to convert data or address inputs to electronic signals to perform logical operations. Converting optical signals to electronic signals and then back to optical signals to perform logical operations incurs significant power consumption, but performing logical operations in the optical domain mitigates this disadvantage.

[0015] In one embodiment, the first nonlinear optical medium includes sum frequency generation, SFG, and a crystal.

[0016] Advantageously, these types of crystals can efficiently produce an output beam having a frequency that is the sum of two input beams.

[0017] In one embodiment, the SFG (sum frequency generation) crystal is a periodically poled lithium niobate (PPLN) crystal. The SFG crystal can have a bandwidth of 19.8 nm to 50 nm.

[0018] Advantageously, such a specification results in a more efficient system for performing logical operations in the optical domain.

[0019] In one embodiment, there is a demultiplexer for receiving the optical data output. The demultiplexer may be configured to selectively output optical data having a predetermined frequency. The optical data having the predetermined frequency may be output to a first optical receiving device. The optical data not having the predetermined frequency may be output to a second optical receiving device.

[0020] Advantageously, a demultiplexer allows for routing of optical data output to a desired destination node. The optical data output provided by the nonlinear optical medium may include unwanted optical signals at different frequencies. The demultiplexer can separate a desired frequency output from the multiple output frequencies and transmit the desired frequency output to a desired address. The unwanted optical signals can remain in a separate channel, such as the main waveguide, and not be routed to the destination address. The demultiplexer ensures that data is transmitted to the destination node only if the sending node uses the correct specific frequencies for both the data input and the address input.

[0021] More advantageously, the demultiplexer can receive optical data outputs that have passed through two or more nonlinear optical media. Thus, the optical data outputs can be associated with two or more addresses of interest. The demultiplexer can be a demultiplexer prism that separates a first signal for a first address, a second signal for a second address, etc. The demultiplexer prism also separates unwanted optical signals. The demultiplexer prism can allow the first separated signal to be transmitted to the first address, the second signal to be transmitted to the second address, etc., while retaining the unwanted signals in the waveguides of the optical switch.

[0022] In one embodiment, the optical switch further includes a second nonlinear optical medium disposed in series with the first nonlinear optical medium such that optical data output by the first nonlinear optical medium is provided as input to the second nonlinear optical medium.

[0023] Advantageously, cascaded series nonlinear optical media allow the optical switch to accommodate multiple nodes, each nonlinear optical medium may correspond to a separate node.

[0024] In one embodiment, there is a demultiplexer prism configured to receive the optical data output from the second nonlinear optical medium and separate the optical data output received from the second nonlinear optical medium 202b into multiple beams.

[0025] Advantageously, the demultiplexer prism allows all of the optical data output from the second nonlinear optical medium to be separated so that the associated beam from the output can be routed to a corresponding address node. That is, the optical data output from the second nonlinear optical medium may include multiple optical beams, each of the multiple optical beams containing data intended for a different address node. The demultiplexer prism separates the multiple optical beams into individual beams so that the individual beams can be transmitted to their intended address nodes.

[0026] In one embodiment, the optical switch further includes a third nonlinear optical medium, the third nonlinear optical medium being disposed in parallel with the first nonlinear optical medium.

[0027] Advantageously, this arrangement also allows the optical switch to accommodate multiple nodes, and to perform more than one nonlinear operation simultaneously.

[0028] In one embodiment, the optical switch further includes a second nonlinear optical medium and a third nonlinear optical medium, the first, second, and third nonlinear optical media being arranged in parallel and each including a PPLN (periodically poled lithium niobate) crystal having a bandwidth of 19.8 nm.

[0029] Advantageously, from the standpoint of switch efficiency, this is considered to be the optimum placement for an optical switch.

[0030] In another aspect, there is a system including an optical switch, the optical switch being a switch according to any of the embodiments described above.

[0031] Advantageously, due to the presence of optical switches, the system performs logic operations entirely in the optical domain, and therefore consumes less power and has higher data throughput than current systems that use prior art electronic switches.

[0032] In another aspect, there is a method of operating an optical switch. The method includes inputting an optical data input and an optical address input to a nonlinear optical medium. The method additionally includes combining the optical data input and the optical address input through the nonlinear optical medium to generate an optical data output. The method also includes outputting the optical data output through the nonlinear optical medium. The frequency of the optical data output depends on the frequency of the optical data input and the frequency of the optical address input.

[0033] Advantageously, the present method allows logical operations to be performed entirely in the optical domain due to the presence of optical switches, and therefore consumes less power and has higher data throughput than current methods of performing data switching using prior art electronic switches.

[0034] One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0035] [Figure 1A] 1 illustrates an example of an optical switch according to aspects of the present disclosure. [Figure 1B] 1 illustrates a further example of an optical switch according to an aspect of the present disclosure. [Figure 2] 10 illustrates additional examples of optical switches according to aspects of the present disclosure. [Figure 3] 1 illustrates another example of an optical switch according to aspects of the present disclosure. [Figure 4] 1 is a flowchart illustrating an example method of operating an optical switch according to aspects of the present disclosure. [Figure 5] 1 illustrates an overview of an exemplary system according to aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0036] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it should be understood that other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the invention. The order of operations is not limited to that described herein and may be varied as would be apparent to one skilled in the art, except for operations that necessarily occur in a particular order.

[0037] It will also be understood that the embodiments and technical features thereof described in the present disclosure may be combined with each other in any combination, unless there is a contradiction between two embodiments or features, in which case any combination of two or more of the above-described embodiments is contemplated and included within the present disclosure. One or more features from any embodiment may be incorporated into any other embodiment, providing one or more corresponding advantages.

[0038] 1A illustrates an example of an optical switch 100. The optical switch 100 may be installed in a network of multiple systems (nodes), where each node requires communication access to every other node. The optical switch has inputs and outputs to every node in the network.

[0039] The optical switch 100 includes a nonlinear optical medium 102. The nonlinear optical medium 102 is used to implement functions that would normally be performed by electronic logic circuits. The nonlinear optical medium 102 is capable of performing an arithmetic operation on the input frequencies provided to the nonlinear optical medium 102. For example, the arithmetic operation can be addition or subtraction of the received frequencies.

[0040] The optical switch further includes an input 104 and an output 106. The input 104 receives an optical data input 108 and an optical address input 110 and provides the optical data input 108 and the optical address input 110 to the nonlinear optical medium 102. The nonlinear optical medium 102 operates on the received optical data input 108 and optical address input 110 to form an optical data output 112. The output 106 provides the optical data output 112.

[0041] Optical data input 108 and optical address input 110 are received from nodes in the network. Optical data input 108 contains data that the node wishes to transmit, and optical address input 110 contains the address of the desired destination node. Optical switch 100 receives optical data input 108 and uses optical address input 110 to enable transmission of the data on optical data input 108 to the destination node.

[0042] For clarity, in the figures, optical data inputs 108 are represented using solid arrows, optical address inputs 110 are represented using dashed arrows, and optical data outputs 112 are represented using dotted arrows. Wherever possible, this representation is used consistently throughout the figures.

[0043] The optical data input 108 is at the D frequency, i.e., f d0-d(D-1) To transmit data, the transmitting node modulates the optical beam to encode the transmitted data in serial form. The optical address input 110 is connected to the A frequency, i.e., f a0-a(A-1) To transmit data, the transmitting node also modulates a light beam, the frequency of which represents the destination node. The destination node may also be called an address node, a target node, or a receiving node. Each destination node has a frequency f a and f d In this way, a source can choose to transmit data optically directly to any of a variety of destination nodes without requiring intermediate conversion to an electronic signal.

[0044] 1B shows another example of an arrangement of optical switch 100. Input section 104 includes a data input section 104a and a separate address input section 104b. Data input section 104a receives an optical data input 108, and address input section 104b receives an optical address input 110.

[0045] The nonlinear optical medium 102 can be a sum frequency generator (SFG). Such a crystal generates a sum frequency a and f d and obtain two beams of frequency f a +f d The efficiency of this conversion depends on many factors, such as beam intensity, and can range from less than 1% up to 50%. Therefore, the output from the nonlinear optical medium 102 may also contain unwanted frequencies. The unwanted frequencies are a +f a , f d +f d and the untransformed beam f a and f d may include:

[0046] The optical data output 112 is provided to a separating means such as a demultiplexer 114. The demultiplexer 114 separates the desired frequency f from the beam of the optical data output 112. a +f d The desired frequency f a +f d can be transmitted to destination address 116. Unwanted frequencies can remain in the main waveguide of optical switch 100, i.e., they do not have to be transmitted to a particular receiver.

[0047] If a network requires multiple switches, a single SFG crystal with a wide bandwidth can be used as the nonlinear optical medium 102. The wide bandwidth increases the number of different wavelengths of light that the nonlinear optical medium 102 can accept, and therefore increases the number of nodes that the optical switch can accommodate.

[0048] Optical switches according to FIG. 1A or FIG. 1B can be used to build a mesh topology of interconnected nodes.

[0049] 2 shows another example of an optical switch 200. The optical switch 200 includes a first nonlinear optical medium 202a and a second nonlinear optical medium 202b arranged in series. As the bandwidth of a nonlinear optical medium, such as an SFG crystal, increases, the conversion efficiency of the nonlinear optical medium decreases. Using multiple nonlinear optical media can accommodate more nodes more efficiently.

[0050] The two nonlinear optical media provided in this diagram are purely exemplary, and one skilled in the art will recognize that more than two nonlinear optical media can be provided in series. For clarity, only two nonlinear optical media are depicted in this diagram.

[0051] The first nonlinear optical medium 202a and the second nonlinear optical medium 202b have different addresses, f a1 +f d and f a2 +f d can be optimized for

[0052] Nonlinear optical media such as SFG have f a +f d The nonlinear optical medium can be designed to perform the nonlinear operation most efficiently. That is, the nonlinear optical medium can be phase-matched to perform the nonlinear operation only in the presence of a specific input. If the frequency of the address beam is f a If the frequency of the data beam is different from f d If the SFG does not match the address and data frequencies, the SFG will a and f d Therefore, in a chain of SFGs, if any of the SFGs in the chain passes f a and f d If it matches, the result (f a+f d ) appears at the end of the chain. All possible outcomes from the operations performed by the chain of SFG crystals can then be separated by a separation means. Any SFG can be separated by f a and f d If it is not adjusted to match, no output will be produced.

[0053] 2, the first nonlinear optical medium 202a receives the optical data input 108 and the optical address input 110. The first nonlinear optical medium 202a outputs one or more optical beams 204. The frequency of the one or more optical beams 202 depends on whether the first nonlinear optical medium 202a is phase-matched to the frequencies of the optical data input 108 and the optical address input 110. If the first nonlinear optical medium 202a is phase-matched to the frequencies of the optical data input 108 and the optical address input 110, the frequency of the optical beam 204 will be the sum of the frequencies of the optical data input 108 and the optical address input 110. If the first nonlinear optical medium 202a is not phase-matched to the frequencies of the optical data input 108 or the optical address input 110, the first nonlinear optical medium 202a outputs an optical beam 204 having the same frequency as the optical data input 108 and the optical address input 110. That is, the first nonlinear optical medium 202 a effectively outputs the optical data input 108 and the optical address input 110 .

[0054] The second nonlinear optical medium 202b then receives the optical beam 204 output from the first nonlinear optical medium 202a along with a second optical address input 206 received from a different node. The second nonlinear optical medium 202b outputs an optical data output 112, the frequency of which depends on the frequency of the optical beam 204 and the frequency of the second optical address input 206. The data output 112 may include multiple beams, each having a different frequency.

[0055] For example, the first nonlinear optical medium 202a is driven at an address frequency f a1 and the second nonlinear optical medium 202b can be phase-matched with the address frequency f a2and both nonlinear optical media can be phase-matched to the frequency f d The optical data input 108 can be phase-matched with a data input of frequency f d and the optical address input 110 has a frequency f a1 , the first nonlinear optical medium 202a has a frequency f d +f a1 The second nonlinear optical medium 202b outputs a light beam 204 having a frequency f d +f a1 , and so output having this frequency passes through the second nonlinear optical medium 202b and is output as optical data output 112.

[0056] As another example, using the same first nonlinear optical medium 202a and second nonlinear optical medium 202b, if the optical data input 108 has a frequency f d and the optical address input 110 has a frequency f a2 , the first nonlinear optical medium 202a has a frequency f a2 , and therefore performs no operation on the input. This input passes through the first nonlinear optical medium 202a as an optical beam 204 and is provided to the second nonlinear optical medium 202b as an input for the second nonlinear optical medium 202b. Because the second nonlinear optical medium 202b is phase-matched to accept an input having such a frequency, the second nonlinear optical medium 202b performs a nonlinear operation on the beam, and generates a frequency f d +f a2 Therefore, the optical data output 112 produces a beam of f d +f a2 The beam includes a beam having a frequency of .

[0057] As another example, using the same first nonlinear optical medium 202a and second nonlinear optical medium 202b, if the optical data input 108 has a frequency f dand the optical address input 110 has a frequency f a3 , neither the first nonlinear optical medium 202a nor the second nonlinear optical medium 202b performs a nonlinear operation on the input. This input passes through both nonlinear optical media unchanged, so that the optical data output 112 has a frequency f a3 beam and frequency f d Similarly, if the optical data input 108 includes a beam having f d , neither the first nonlinear optical medium 202a nor the second nonlinear optical medium 202b performs a nonlinear operation on the input, and the input is output to the data output 112 unchanged.

[0058] The optical data output 112 is passed through a demultiplexer prism 208, or wavelength division demultiplexer, which separates the multiple beams that form the data output 112. Optical data having a predetermined frequency is output to a first optical receiving device 210. Optical data not having a predetermined frequency may be output to a second optical receiving device 212. Thus, the demultiplexer prism 208 routes the data to the appropriate address node depending on the frequency it receives as an input. If none of the nonlinear optical media within the optical switch 200 are tuned to match the frequencies of the data input and address input, no output will be generated.

[0059] The serial chain structure of nonlinear optical media according to FIG. 2 can be used to generate bus and star network topologies.

[0060] 3 shows another example of an optical switch 300. The optical switch 300 includes a first nonlinear optical medium 302a, a second nonlinear optical medium 302b, and a nonlinear optical medium 302c arranged in parallel. The optical switch 300 further includes a splitter 304 and a wavelength division multiplexer 306.

[0061] The three nonlinear optical media shown in this figure are purely illustrative, and one skilled in the art will recognize that any number of nonlinear optical media greater than three may be arranged in parallel. For example, there may be two nonlinear optical media arranged in parallel or four nonlinear optical media arranged in parallel. For clarity, only three nonlinear optical media are shown in this figure.

[0062] Splitter 304 receives optical data input 308 and optical address input 310 and splits the received input across each of the nonlinear optical media. In this example, splitter 304 splits each of optical data input 308 and optical address input 310 into three beams and provides the beam of optical data input 308 and the beam of optical address input 310 to each of the nonlinear optical media. That is, splitter 304 allows first nonlinear optical medium 302 a, second nonlinear optical medium 302 b, and nonlinear optical medium 302 c to receive optical data input 308 and optical address input 310, respectively.

[0063] Each of the nonlinear optical media provides an output (312a, 312b, 312c) based on the frequency of the received beam and whether the nonlinear optical medium is phase-matched to the received frequency. If either the first nonlinear optical medium 302a, the second nonlinear optical medium 302b, or the nonlinear optical medium 302c is phase-matched to use data having the frequencies of the optical data input 308 and the optical address input 310, that nonlinear optical medium performs a nonlinear operation on the input beam. The output from that nonlinear optical medium can then be routed to a desired destination node via a wavelength division multiplexer 306. The wavelength division multiplexer 306 combines the received outputs (312a, 312b, 312c) into a combined output 314. This output 314 can be provided to a separating means, such as a demultiplexer, to route only the desired data to the desired destination node.

[0064] For example, the first nonlinear optical medium 302a is driven at an address frequency f a1and the second nonlinear optical medium 302b can be phase-matched to the address frequency f a2 and the third nonlinear optical medium 302c can be phase-matched to the address frequency f a3 and all nonlinear optical media can be phase-matched to the frequency f d If the optical data input 108 has a frequency f d and the optical address input 110 has a frequency f a1 , the first nonlinear optical medium 302a has a frequency f d +f a1 The second and third nonlinear optical media are not phase-matched to the address frequency, so the input beam passes through these media to form outputs 312b and 312c, respectively. The output beams (312a, 312b, 312c) travel to wavelength division multiplexer 306, where they are combined to form output 314. Output beam 314 has a frequency f d +f a1 beam, so that output beam 314 can be routed to a desired destination.

[0065] Those skilled in the art will appreciate that an optical switch may include multiple nonlinear optical media, with the nonlinear optical media being provided in both series and parallel configurations.

[0066] 4 illustrates an exemplary method 400 of operating an optical switch, which may be optical switch 100. In step 402, an optical data input 108 and an optical address input 110 are input to nonlinear optical medium 102. In step 404, nonlinear optical medium 102 combines optical data input 108 and optical address input 110 to generate optical data output 112. In step 406, nonlinear optical medium 102 outputs optical data output 112. The frequency of optical data output 112 depends on the frequency of optical data input 108 and the frequency of optical address input 110.

[0067] The method may further include providing the optical data output 112 to a demultiplexer 114. The method may further include separating the optical data output 112 into multiple beams and selectively outputting, by the demultiplexer 114, the optical data having a desired frequency. The particular optical data may be transmitted or output to a first optical receiver. The optical data not having the desired frequency may be output to a second optical receiver.

[0068] Method 400 may further include performing any of the operations described in connection with the optical switch of any of Figures 1A, 1B, 2, or 3. For the sake of brevity, such operations will not be repeated here.

[0069] Current prior art electronic switches consume 850 watts (W), but the passive nature of the network switch of the present invention eliminates the need for electronic power in the switching logic, essentially reducing the power required for the switching logic by 100%. However, a power budget of up to 80 W is still available for the amplification of input signals that may be required for the optical switch. Even with this power budget, a 90% power reduction is achieved. MatLab® simulations indicate that 20 W of power may be required for amplification in the integrated switching, and up to 40 W may be required for benchtop switching. This is a significant improvement over standard electronic switching circuits.

[0070] Further simulations were performed using Matlab® to model the performance of a single broadband SFG crystal, three SFG crystals in series, and three SFG crystals arranged in parallel. The simulations included 1 km of fiber cable on either side of a 5 × 5 mm lithium niobate integrated chip. A constant input power of 100 mW was assumed in the simulations. The single broadband SFG crystal was a 12.5 nm PPLN, while the series and parallel configurations used 4.3 nm PPLN. The results concluded that using a single broadband SFG crystal is more efficient than using multiple smaller bandwidth PPLNs in an integrated setup, with the series configuration being the least efficient. A single broadband crystal is optimal, especially for integrated setups with a low port count. In a benchtop setup, a single broadband SFG was found to be the least efficient, while a configuration with three parallel SFG crystals was optimal. The configuration with three parallel SFG crystals is estimated to be optimal for port counts greater than 20.

[0071] A system may be provided that includes an optical switch according to any of Figures 1A, 1B, 2 or 3. The system may further include conversion means for converting a signal output from the optical switch to a lower frequency. The conversion means may include a down-converter. Using the conversion means to convert the optical data output allows the output signal to be detected by a standard transceiver.

[0072] The optical switch described herein in connection with the network switch can be used in any switching embodiment. For example, the optical switch can be used for long-distance switching via satellite. The optical switch can be used for XPU interconnects. An XPU interconnect is a switch that sits at a low level and connects to the memory of each processor on a multiprocessor motherboard. Traditionally, a motherboard with multiple processors has shared memory, and all processors can access that shared memory. However, this can cause race conditions and gaps in processing time when multiple processors need to access the memory simultaneously. An XPU interconnect switches data directly to each processor's private memory.

[0073] 5 illustrates an exemplary system 500. In this system overview, the system 500 includes three optical switches and downconversions in parallel. The exemplary system 500 includes multiple servers 502a, 502b, and 502c. These servers may also be referred to as nodes. Each node may be connected to a corresponding transceiver 504a, 504b, and 504c to transmit and receive data on optical signals transmitted between the multiple nodes.

[0074] The system 500 further includes a fiber combiner 506 for receiving optical signals transmitted from each of the multiple transceivers 504a, 504b, and 504c. Because each transceiver can transmit an optical signal using a separate optical fiber, the fiber combiner receives the optical signals via three input optical fibers. The fiber combiner 506 combines the optical signals received from each of the input optical fibers so that the optical signals can be further transmitted through the system 500 using fewer optical fibers. For example, the fiber combiner 506 can combine the signals received from the three input optical fibers into a single output optical fiber. The single output optical fiber then carries each of the signals received from the three input optical fibers. Providing the optical signals on a single optical fiber allows for efficient transmission of the optical signals over long distances.

[0075] In the exemplary system 500, the signal output from the fiber combiner 506 is provided to an optical amplifier 508, which may be an erbium-doped fiber amplifier, that amplifies the optical signal to compensate for optical losses in the optical fiber without converting the optical signal to an electrical signal.

[0076] The amplified optical signals output from the optical amplifier 508 are input to a wavelength division multiplexer (WDM) demultiplexer 510 where they are separated and provided to each optical switch. Signals of different wavelengths are provided on separate optical fibers. The optical data output from the WDM demultiplexer, in this case having a wavelength of 1554.5 nm, is input to a further fiber splitter 512 so that the optical data can be separated and transmitted to each optical switch simultaneously.

[0077] The signals from the WDM demultiplexer 510 and fiber splitter 512 are combined by fiber combiners 514a, 514b, and 514c. Each fiber combiner is associated with a corresponding optical switch 516a, 516b, and 516c. In this case, three optical switches are arranged in parallel. The fiber combiners combine the data and address optical signals received from two separate optical fibers into a single optical fiber. Each optical switch receives optical signals corresponding to its optical data input and optical address input from its corresponding fiber combiner.

[0078] Optical switches 516a, 516b, 516c perform logical operations on the data inputs and address inputs and output optical data outputs. The optical data outputs from each optical switch are provided to a further fiber combiner 518 for combining the optical data outputs received on the separate optical fibers into a single optical fiber. The fiber combiner 518 may include a wavelength division multiplexer.

[0079] The output from the further fiber combiner 518 is provided as an input to a bandpass filter 520. The bandpass filter passes light of desired wavelengths and absorbs or reflects light of other wavelengths. The bandpass filter may include a demultiplexer prism.

[0080] The signal output from the bandpass filter 520 is transmitted to a photodetector 522, which may convert the received optical signal to an electrical signal. The output from the photodetector may be transmitted to a further wavelength division multiplexer 524, which may process the received signal, extract data from the received signal, and transmit the extracted data to an intended destination node.

Claims

1. an input for receiving an optical data input and an optical address input; an output for outputting an optical data output; a first nonlinear optical medium, the first nonlinear optical medium is arranged to combine the optical data input and the optical address input to produce the optical data output; An optical switch, wherein the frequency of the optical data output is dependent on the frequency of the optical data input and the frequency of the optical address input.

2. 2. The optical switch of claim 1, wherein the inputs include a data input for receiving the optical data input and an address input for receiving the optical address input.

3. 3. An optical switch according to claim 1 or 2, wherein the frequency of the optical data output is dependent on an arithmetic operation of the frequency of the optical data input and the frequency of the optical address input.

4. An optical switch according to any preceding claim, further comprising a demultiplexer for receiving said optical data output.

5. 5. The optical switch of claim 4, wherein the demultiplexer is arranged to selectively output optical data having a predetermined frequency.

6. 6. The optical switch according to claim 5, wherein the optical data having the predetermined frequency is output to a first optical receiving device.

7. 7. The optical switch according to claim 5, wherein the optical data not having the predetermined frequency is output to a second optical receiving device.

8. further comprising a second nonlinear optical medium; The optical switch of any one of claims 1 to 7, wherein the second nonlinear optical medium is arranged in series with the first nonlinear optical medium such that optical data output by the first nonlinear optical medium is provided as input to the second nonlinear optical medium.

9. 9. The optical switch of claim 8, further comprising a demultiplexer prism configured to receive the optical data output from the second nonlinear optical medium and to separate the received optical data output into a plurality of beams.

10. further comprising a third nonlinear optical medium; 10. The optical switch according to claim 1, wherein the third nonlinear optical medium is arranged in parallel with the first nonlinear optical medium.

11. 11. The optical switch according to claim 1, wherein the nonlinear optical medium is a sum frequency generation medium, a SFG medium, or a crystal medium.

12. The optical switch of claim 11 , wherein the SFG crystal is a periodically poled lithium niobate, PPLN, crystal.

13. 13. The optical switch according to claim 11, wherein the SFG crystal has a bandwidth of 19.8 nm to 50 nm.

14. A system comprising an optical switch according to any one of claims 1 to 13.

15. 1. A method of operating an optical switch, comprising: inputting an optical data input and an optical address input to a nonlinear optical medium; combining, with the nonlinear optical medium, the optical data input and the optical address input to generate an optical data output; and outputting the optical data output by the nonlinear optical medium; A method wherein the frequency of the optical data output is dependent on the frequency of the optical data input and the frequency of the optical address input.

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