Partially colored flexgrid wavelength-division multiplexer / demultiplexer

Abstract

To provide a wavelength division multiplex apparatus and optical modules in which a layer of arrayed waveguides is used to extend the number of ports of wavelength selective switches used in multiplexing and / or demultiplexing optical signals transported over an optical network.SOLUTION: An apparatus 100 includes: optical modules 108; and a wavelength selective switch (WSS) 112, a contentionless WSS 116 and / or a colorless splitter / combiner 120. The apparatus is coupled to transponders 104, and functions as a wavelength division multiplexer / demultiplexer to multiplex or demultiplex optical signals that are received from or sent to the transponders 104. In the multiplex or addition direction, each optical module receives optical data signals from a transponder, combines the received signal into an optical signal 128, and transmits it via a WSS or combiner over a transport fiber pair 132 to far-end or remotely located systems, apparatuses or equipment.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Wavelength division multiplexing (WDM) technology allows data transmission using multiple wavelengths of light over an optical fiber medium, with each wavelength forming a different channel. More specifically, optical signals at different wavelengths (colors) are multiplexed onto a single optical fiber. This allows more data to be transmitted over a single optical fiber, and as a result, typically increases the capacity of the optical data transmission network. WDM systems are generally considered to be of two types: coarse WDM (CWDM) and dense WDM (DWDM). CWDM systems are typically considered to be systems that use fewer than eight active wavelengths per fiber. DWDM systems are typically considered to be systems that use more than eight active wavelengths per fiber. DWDM systems support optical data rates of hundreds of gigabits per second (Gb / s) and even terabits per second (Tb / s). These higher optical data rates can be provided via a flexible grid pattern ("flexigrid"), where different optical signals have different bandwidths or spectral widths. In effect, a flexigrid allows each wavelength of an optical signal to be defined as having an individual spectral width.

[0002] The multiplexing and demultiplexing of multiple optical signals can be accomplished using different optical technologies, including but not limited to wavelength selective switches (WSS), arrayed waveguide gratings (AWG), and passive colorless splitter combiners. In the case of WSS-based and AWG-based architectures, a single WSS or AWG device is typically used to provide the multiplexing / demultiplexing capability to fill the transmission spectrum of an optical communication link. WSSs allow flexible routing of optical signals on a WDM network. For example, a WSS can route multiple wavelengths on a common port to any one of several multi-wavelength ports. A WSS typically has a limited number of ports. A layer of passive colorless optical splitters / combiners can be used to increase the number of effective ports on a WSS.

[0003] AWGs are used at the transmitter to combine channels of different wavelengths into a single optical fiber, and they are also used at the receiver to separate the individual channels. Summary of the Invention

[0004] The disclosed technology is directed to WDM nodes that enable efficient multiplexing or demultiplexing of multiple optical signals having different bandwidths, e.g., providing flexi-grid functionality, while mitigating or avoiding scaling insertion loss with the number of ports. For example, the disclosed technology may take the form of AWG-based WDM modules or sub-modules, each functioning to multiplex and / or demultiplex one or more wavelengths or channels. In effect, layers of AWGs are used to expand the number of ports used in multiplexing and / or demultiplexing optical signals transmitted through an optical network. The insertion loss of AWGs does not scale with the number of ports. Thus, layers of AWGs enable flexi-grid functionality while mitigating having loss scale with the number of ports. In contrast, the insertion loss of colorless optical splitters / combiners typically scales with the number of ports, which can create power budget challenges for some optical transceivers. Aspects of the disclosed technology mitigate such losses.

[0005] Aspects of the disclosed technology may include an apparatus, system, optical module(s) or process for wavelength division multiplexing and / or demultiplexing of optical signals. For example, the disclosed technology may include a wavelength division multiplexing device including a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of transponders for transmission on a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders, the plurality of optical modules configured such that spectrally adjacent optical signals are mapped to corresponding first input ports on different modules of the plurality of optical modules, each optical module having an optical amplifier having an output and an input, the input of the optical amplifier being coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

[0006] According to this aspect of the disclosed technology, the apparatus may include a wavelength selective switch having a plurality of multi-wavelength ports and a common port, the common port having a common optical signal formed from optical signals input to the plurality of multi-wavelength ports, each multi-wavelength port being associated with an output of an optical amplifier of an optical module, and the common port being coupled to a transmission fiber. The apparatus may further include a contention-free wavelength selective switch coupled between the plurality of multi-wavelength ports of the wavelength selective switch and an output of an optical amplifier of each optical module. Furthermore, the plurality of optical modules includes N optical modules, and the plurality of multi-wavelength ports includes N multi-wavelength ports, where N is an integer value equal to or greater than 2. Still further, the plurality of first input ports includes M first input ports, where M is an integer value greater than 2 and equal to N.

[0007] Further, according to this aspect of the disclosed technology, each of the plurality of optical modules has at least two first arrayed waveguides coupled to two or more of the plurality of first input ports. Furthermore, the optical data signals received at each of the plurality of first input ports from each of the plurality of transponders are at different wavelengths. Still further, the spectrally adjacent optical signals include optical signals having center wavelengths within a predetermined contiguous spectral bandwidth, the center wavelength being adjacent to another center wavelength within the predetermined contiguous spectral bandwidth.

[0008] Further, according to this aspect of the disclosed technology, each of the plurality of optical modules includes a second arrayed-waveguide grating including a plurality of output ports configured to provide a transmission data signal received on the transmission fiber to the plurality of transponders. Further, the second arrayed-waveguide grating includes a second input port that receives the transmission data signal and separates the transmission data signal into individual receive signals for each of the plurality of output ports. Still further, the second input port is coupled to a plurality of multi-wavelength ports of the wavelength selective switch. Furthermore, the plurality of output ports are equal to a plurality of first input ports of the first arrayed-waveguide grating.

[0009] Further in accordance with this aspect of the disclosed technology, the apparatus includes a colorless splitter / combiner having a plurality of colorless input ports and a common port, the common port having a common optical signal formed from optical signals input to the plurality of multi-wavelength ports, one of each colorless input port being associated with the output of one optical amplifier of the optical module, and the common port being coupled to a transmission fiber.

[0010] Another aspect of the disclosed technology is an optical module for a wavelength division multiplexer or demultiplexer, comprising: a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; and a first arrayed waveguide grating including: An optical module comprising: a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission on a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; and an optical amplifier having an output and an input, the input of the optical amplifier being coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

[0011] According to this aspect of the disclosed technology, the optical module may further include a second arrayed-waveguide grating including a plurality of output ports configured to provide a transmission data signal received on the transmission fiber to a plurality of optical transponders. Furthermore, the second arrayed-waveguide grating includes a second input port that receives the transmission data signal and separates the transmission data signal into individual receive signals for each of the plurality of output ports. Furthermore, the second input port is coupled to a plurality of multi-wavelength ports of the wavelength selective switch. Still further, the plurality of output ports are equal to a plurality of first input ports of the first arrayed-waveguide grating.

[0012] Another aspect of the disclosed technology includes a plurality of transponders, a transmission fiber, and a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including one first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of the plurality of transponders for transmission on the transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders, the plurality of optical modules each optical module having the first arrayed waveguide grating. a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of the plurality of transponders for transmission over the transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; and a plurality of optical modules, each optical module having an optical amplifier having an output and an input, the input of the optical amplifier being coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

[0013] Another aspect of the disclosed technology includes an apparatus, optical module, or system that performs a process of mapping spectrally adjacent optical signals received from a transponder to corresponding first input ports on different optical modules of a plurality of wavelength division sub-multiplexing optical modules. [Brief description of the drawings]

[0014] [Figure 1] 1 illustrates an exemplary apparatus or system according to one aspect of the disclosed technology. [Diagram 2] 1 illustrates an example of an optical signal occupying a portion of the optical spectrum in accordance with the disclosed technology. [Diagram 3] 1 illustrates an exemplary apparatus or system according to one aspect of the disclosed technology. [Figure 4] 1 illustrates an exemplary apparatus or system according to one aspect of the disclosed technology. [Diagram 5]1 illustrates an example of an optical signal occupying a portion of the optical spectrum in accordance with the disclosed technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 illustrates an example of an apparatus or system 100 according to one aspect of the disclosed technology. The apparatus 100 includes an optical module 108 and different configurations including a wavelength selective switch (WSS) 112, a contention-free WSS 116, and / or a colorless splitter / combiner 120. The apparatus 100 is coupled to a transponder 104. The apparatus 100 functions as a wavelength division multiplexer / demultiplexer to multiplex or demultiplex optical signals it receives from or transmits to the transponder 104. In some examples, the transponder 104 may be included as part of the apparatus 100.

[0016] In the multiplexing or add direction, each optical module 108 serves to receive optical data signals from the transponders 104 and combine the signals received by the transponders 104 into an optical signal 128. The optical signal 128 from each optical module 108 is then provided to the WSS 112, the contention-free WSS 116, or the colorless splitter / combiner 120 for transmission to a far-end or remotely located system, device, or equipment via a transmission fiber pair 132. For example, a system, device, or equipment may be located in a data center that also houses the source device 100, or in another data center at a different location coupled to the fiber pair 132, and serve as a destination or source of data transmitted over a network including the fiber pair 132. For example, networks may vary in size, including cross-campus communications between nearby data centers, including communications over underwater transmission fibers across continents. As described further below, the optical module 108, and therefore the apparatus or system 100, can be adapted to support different applications by configuring the components that make up the optical module and how the optical module is coupled to the fiber pairs.

[0017] A fiber pair includes two fibers, one for each direction of transmission. Optical module 108 is coupled to transponder 104 and WSS 112, contention-free WSS 116, or colorless splitter / combiner 120 via optical fiber pairs 135 and 139.

[0018] In the demultiplexing direction, each optical module 108 functions to separate the optical signal 128 it receives from the WSS 112 , the contention-free WSS 116 , or the colorless splitter / combiner 120 and provide an optical data signal to the transponder 104 .

[0019] As shown, the transponder 104 includes both a transmitter element (Tx) and a receiver element (Rx). Thus, the transponder functions to transmit and receive optical data signals, respectively, for eventual transmission over the fiber pair 135. In the example of FIG. 1, to simplify the illustration, each optical module 108 is shown to communicate with one transponder. However, in other examples, and in more typical practical applications, each optical module 108 will communicate with multiple transponders 104 via ports 160, 162 of the optical module 108. Each of the multiple transponders communicating with a given optical module 108 will communicate using signals at different wavelengths, and possibly with different bandwidths, as further described below. The transponder 104 will also communicate with one or more other systems, such as, for example, a host system, that act as data sources and data sinks for the information carried by the optical data signals. Connections to those systems are not shown for simplicity, but typically include electrical connections for information-carrying signals, such as, for example, baseband signals. The wavelength of the transponder is typically tunable over a range around a central wavelength.

[0020] Each of the optical modules 108 includes a first arrayed waveguide grating (AWG) 170 and a second AWG 174. Each AWG 170 has a plurality of input ports 1601 to 1604. Mand one output port 176. The AWG 174 includes one input port 179 and a plurality of output ports 1621 to 162 M and AWG 174. AWG 170 and AWG 174 function as colored combiners and splitters, respectively, and may be considered functionally as sub-multiplexer or sub-demultiplexer modules. Specifically, input ports 160 are configured as input channels, with each input channel only accepting light within a particular wavelength range or wavelength window. Similarly, output ports 162 are configured as output channels, with each output channel only outputting light in a particular wavelength range or window. For example, as shown in FIG. 3, for each optical module 108, for an input port 160 of AWG 170 operating at a given wavelength, AWG 174 has a corresponding output port operating at the same given wavelength. For example, input port 1 and output port 1 in optical module 108 receive and transmit signals at the same wavelength as each other, input port 2 and output port 2 receive and transmit signals at the same wavelength as each other (but different from the other input / output ports), etc. In this regard, an input port / output port pair comprises an input port and an output port on the AWG that respectively receive and transmit optical signals at the same wavelength.

[0021] Additionally, spectrally adjacent optical signals, e.g., spectrally adjacent optical channels or wavelengths, may enter the same corresponding port but different AWGs. For example, each of the transponders 104 is connected to the same port X of each optical module 108. Thus, the optical signals received at port X of the different AWGs of the apparatus 100 occupy a given spectral window or contiguous portion of the optical spectrum based on the spectrally adjacent optical signals.

[0022] The optical signal at the output port 176 of each AWG 170 is fed to the input ports 1601 to 160 MThe output port 176 is a wavelength division multiplexed signal including an optical signal at each wavelength received at the output port 176. The output port 176 is coupled via a fiber to an optical amplifier 182. The optical amplifier 182 may be an optical fiber amplifier or a semiconductor amplifier. The optical fiber amplifier may be an erbium doped fiber amplifier or a fiber Raman amplifier. According to the disclosed technology, the insertion loss of an AWG is typically lower than that of a colorless optical splitter / combiner, e.g., 14 dB (colorless optical splitter / combiner) to less than 4 dB for a 1×16 splitting ratio, so the optical amplifier 182 may be a less expensive optical amplifier with lower gain. Furthermore, the optical amplifier is optional, and there may be implementations that do not require an amplifier, e.g., depending on the reach of the system. Other implementations include two amplifiers, one in the add direction and another in the drop direction. Furthermore, other implementations may include an amplifier only in the drop direction.

[0023] The optical amplifier 182 amplifies the optical signal it receives from the AWG 170 and provides the amplified optical signal, for example, to the WSS 112. The WSS 112 consists of N multi-wavelength ports 187 and a single common port 189. For simplicity in FIG. 1, the N multi-wavelength ports 187 are shown as a single connection point. The WSS 112 operates such that each wavelength from the common port 189 can be switched or routed to any one of the N multi-wavelength ports, and vice versa. In essence, the WSS 112 switches wavelengths or channels across the system or device 100 and functions as a programmable optical multiplexer / demultiplexer. The optical signal from the common port 189 is transmitted via the fiber pair 132 to a remote or far-end wavelength division demultiplexer, which may be configured as described herein or may use other configurations.

[0024] For example, when the wavelength division multiplexer is configured in the demultiplexing direction in accordance with the disclosed techniques, WSS 112 routes the optical signals it receives over fiber pair 132 to the appropriate multi-wavelength port of multi-wavelength ports 187. Specifically, WSS 112 routes the optical signals to the appropriate optical module 108. AWG 174 of optical module 108 demultiplexes or separates the optical signals it receives at its input port 179 into individual wavelengths or channels and outputs those signals to the appropriate output ports of output ports 162.

[0025] As a specific example, each of the transponders 104 is shown as transmitting and receiving optical signals via port X of the AWGs 170 and 174. 1.X , 104 2.X , and 104 N.X Each of the AWGs 1701 and 1741 uses a spectrally adjacent optical signal or channel, as shown in FIG. 2 using spectrum 200. The spectrally adjacent optical signals include signal 204 of AWG 1701 and AWG 1741, signal 208 of AWG 1702 and AWG 1742, and signal 209 of AWG 1703. N and 174 N 208. As shown, the signal is treated as a Flexi-Grid optical signal, and signal 212 occupies a different spectral bandwidth than either of signals 204 and 208. Furthermore, the signals are spectrally adjacent to one another, such that the signals occupy contiguous portions of the optical spectrum.

[0026] In the example of FIG. 2, the AWG 170, 174 has a 4800 GHz bandwidth and 16 input / output ports or channels. The spectrum bandwidth is therefore divided into bins of 300 GHz, i.e., a free spectral range of 4800 GHz / 16=300 GHz per bin. The free spectral range (FSR) represents the distance between the center frequencies of each AWG. In this example, the total spectrum is 4800 GHz, and there are 16 ports, so the FSR is 300 GHz. Thus, the bandwidth per channel is 300 GHz. In other words, each input / output port pair has a channel of 300 GHz. The spectrum-to-port mapping involves a two-step process in which a larger spectrum window is first selected (e.g., 300 GHz), and then the signals at the AWG ports are assigned sub-portions of the spectrum window.

[0027] In the demultiplexing or dropping direction, the coherent gain provided by the receiver's local oscillator is advantageously used to avoid the use of amplifiers, so the disclosed technique is suitable for the use of lower gain, less expensive optical amplifiers only in the multiplexing or adding direction. However, as mentioned above, other implementations are possible where amplifiers are not used in either or both directions. Furthermore, the architecture of the device or system can limit noise leakage (in contrast, out-of-band noise from multiple optical signals is increased in architectures that use colorless multiplexers / demultiplexers instead of AWGs). Furthermore, filters such as tunable optical filters (TOFs) may be avoided on the multiplexing side in the disclosed device or system.

[0028] As shown in FIG. 1, the apparatus 100 may also be configured to include a contention-free WSS 116 coupled between the WSS 112 and the optical module 108. The contention-free WSS 116 includes an M×N switching fabric, where M corresponds to the degree, or WSS modules connecting at colorless, directionless, and contentionless (CDC) nodes. N corresponds to the number of add / drop ports directly coupled to either the transponder or the pre-multiplexer module 108. The dimensions of the M×N WSS are not necessarily matched to the dimensions of the pre-multiplexer / demultiplexer module 108.

[0029] The contention-free WSS 116 provides contention-free routing of the channels or wavelengths being used. In general, contention-free routing allows the WSS 116 to establish a first connection between a first input port and a first output port at one wavelength without preventing a second connection from being established between a second input port and a second output port at that same wavelength. Thus, the contention-free WSS 116 provides this flexibility, allowing any channel or wavelength to be routed to any port at the WSS 112. The output ports of the WSS 116 are connected to different and / or multiple WSS modules 112.

[0030] Also, as shown in FIG. 1, a 1×N colorless splitter / combiner 120 may be coupled to the optical modules 108 and fiber pairs 132 in place of the WSS 112, or in place of the WSS 112 and the contention-free WSS 116. The 1×N colorless splitter / combiner 120 combines the N optical signals it receives from the N optical modules in a single optical signal for transmission on the fiber pair 132. In the demultiplex or drop direction, the 1×N colorless splitter / combiner 120 separates the optical signals it receives on the fiber pair 132 into N optical signals for the N optical modules. In contrast to configurations using only the WSS 112, or both the WSS 112 and the contention-free WSS 116, the colorless splitter / combiner configuration does not offer the routing flexibility of other configurations and is more suitable for point-to-point type architectures.

[0031] FIG. 3 illustrates an apparatus or system 300 according to one aspect of the disclosed technology. The apparatus or system 300 is simplified in terms of the number of input / output ports compared to FIG. 1, but includes additional details regarding the connections between the optical modules 310 and the WSS 330 and the channel or wavelength mapping. More specifically, the apparatus or system 300 includes four optical modules 310 coupled between the WSS 330 and a number of transponders 350. In the multiplexing or add direction, each optical module 310 includes a first AWG 312 and an amplifier 314. In the demultiplexing or drop direction, each optical module 310 includes a second AWG 316. Each AWG 312, 316 has four input or output ports.

[0032] The input and output ports of each AWG are connected to a respective transponder 350, as shown for optical module 3101. In this example, the device is configured to process 16 channels, each channel corresponding to a different wavelength. Specifically, the WDM grid includes the following channels at the following wavelengths: [Table 1] Spectrally adjacent channels are shown as adjacent to each other. In accordance with the disclosed technique, spectrally adjacent signals are mapped to the same port on different AWGs, resulting in the following, as shown in FIG. In the case of AWG3121 and 3141 of optical module 3101 [Table 2] In the case of AWG3122 and 3142 of optical module 3102 [Table 3] In the case of AWG3123 and 3143 of optical module 3103 [Table 4] In the case of AWG3124 and 3144 of optical module 3104 [Table 5]

[0033] Referring to optical module 3101, the optical signals provided by the transponders of each of CH1 (λ1), CH5 (λ5), CH9 (λ9), and CH13 (λ13) are combined by AWG 3121 into an optical signal provided to amplifier 3141. Amplifier 3141 amplifies the optical signal it receives and transmits the optical signal to WSS 330. As shown, WSS 330 has four ports, each in communication with optical module 310. WSS 330 processes the optical signal it receives from optical module 3101 and routes the signal to fiber 340 for transmission to another system. Channels mapped to other optical modules would be similarly processed in the multiplex or add direction.

[0034] In the demultiplex or drop direction, WSS 330 receives the optical signal on fiber 342 and routes each channel to the appropriate optical module 310. For example, for optical module 3101, this would include CH1 (λ1), CH5 (λ5), CH9 (λ9), and CH13 (λ13).

[0035] According to the disclosed technology, each channel mapped to the same corresponding port will occupy a contiguous portion of the optical spectrum, as described above. Specifically, in this example, CH1, CH2, CH3, and CH4 will occupy spectral windows that occupy contiguous portions of the optical spectrum. Similarly, CH5, CH6, CH7, and CH8, CH9, CH10, CH11, and CH12, and CH13, CH14, CH15, and CH16 will also occupy spectral windows that occupy contiguous portions of the optical spectrum, respectively.

[0036] 4 illustrates an exemplary apparatus or system 400 according to one aspect of the disclosed technology. As illustrated, the apparatus or system 400 includes N optical modules 410 coupled to a transponder 424 and a WSS 432, a contention-free WSS 436, and a WSS 438 or colorless splitter / combiner 440. Compared to FIG. 1 or 3, the optical module 410 is configured differently than the optical module 108. Otherwise, the WSSs 432 and 438, the contention-free WSS 436, and the colorless splitter / combiner 440 are configured and function similarly to their counterparts in FIG. 1 or 3.

[0037] As shown in Figure 4, each optical module 410 includes a first pair of AWGs 411, 413 in the multiplexing / adding direction and a second pair of AWGs 415, 417 in the demultiplexing / dropping direction. Each optical module 410 also includes a pair of colorless splitters / combiners 418, 419. The colorless splitter / combiner 418 combines the two optical signals it receives from the AWGs 411, 413 into an optical signal that is provided to the amplifier 421. The colorless splitter / combiner 419 splits the signal it receives on fiber 4231 into an optical signal that is provided to the AWGs 415, 417.

[0038] As also shown in Figure 4, the number of input / output ports of the optical unit is divided between two AWGs. Specifically, the M input ports are divided between two AWGs 411, 413, and the M output ports are divided between AWGs 415, 417. Each of these AWGs has fewer ports compared to the AWGs of Figure 1. Each AWG 411, 413 includes M / 2 ports, while each AWG 170, 174 of Figure 1 has M ports.

[0039] Other implementations are possible. For example, the number of AWGs can include more than one per add / mux or drop / demultiplex path. For example, each path can include four AWGs. To accommodate such a configuration, the splitter / combiner would need to include a 1×4 splitter combiner.

[0040] 4 and 5, an apparatus or system 400 can be implemented to achieve different spectral mappings 500. In a first example 510, AWGs 411 and 413 are configured identically, while in a second example 520, AWGs 411 and 413 are shifted by FSR / 2.

[0041] In operation, the spectral profile 512 of the first example 510 is reached in an additional direction as follows. First, note that by using two identical AWGs 411, 413, each AWG needs to include only half the number of ports compared to the configuration of FIG. 1. In this regard, the spectral passbands of the AWGs 411, 413 can be configured to be twice as large. In the example shown through FIG. 5, each port of the AWGs 411, 413 is configured to have the same passband as described with respect to FIGS. 1 and 2. For example, for the first optical module 4101, port 1 of the first AWG 411 is assigned the lower half 516 of the passband or spectrum 518. Port 1 of the second AWG 413 is assigned the upper half 520 of the spectrum 518. In the example where the transponder into port 1 of AWG411 has a bandwidth that exceeds the lower half 516 of the spectrum and therefore occupies the upper half 520, the signal connected to port 1 of AWG413 would need to be configured to avoid overlapping with the signal at port 1 of AWG411.

[0042] As illustrated via spectral profile 546, signals input to the second optical module 4102 may be processed similarly in the add direction. Similarly, signals input to other modules may be processed similarly. Additionally, signals input to each port of each module will be processed similarly, but will be transmitted in different spectral windows, as described above with respect to FIG. 1 and shown in FIG. 2. In the drop direction, the spectrum will look the same as in the add direction, and the signals will be processed similarly at their respective spectral frequencies, as described with respect to FIG. 1 and FIG. 2.

[0043] The configuration shown in Figure 4 effectively doubles the spectral width of each AWG port while maintaining the multiplexing or demultiplexing ratio of Figure 1. This allows for greater flexibility in FlexiGrid implementations (e.g., larger continuous spectral windows).

[0044] In another example 520, AWGs 411 and 413 are not configured to be identical. In this example, AWGs 411 and 413 are configured to have the same FSR, but their respective grids are shifted. As shown, this configuration allows the transponder signal to extend beyond the upper and lower boundaries of its assigned spectral passband.

[0045] The above examples include configurations with two AWGs per optical module (FIG. 1) and configurations with four AWGs per optical module (FIG. 2). Other configurations are possible. For example, the number of AWGs per optical module may include more than two AWGs based on factors such as cost, flexibility, and damage loss. In this regard, more AWGs may provide more spectrum flexibility in accordance with the description related to FIG. 5, but the cost increases with the number of AWGs. The number of AWGs may scale differently if the source and destination are within a given data center or connected remotely over a wide area network. Furthermore, the system gains provided by the disclosed technology make it attractive for applications seeking to utilize coherent pluggables in long-haul networks. Thus, the disclosed technology may find use across a wide range of transponders.

[0046] The disclosed technology may take the form of an apparatus, system, or process that includes the following features and sub-features.

[0047] F1. A wavelength division multiplexing device, a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; the plurality of optical modules are configured such that spectrally adjacent optical signals are mapped to corresponding first input ports on different optical modules of the plurality of optical modules; each optical module having an optical amplifier having an output and an input, the input of the optical amplifier coupled to receive the combined signal from the first output port of the first arrayed waveguide grating; Wavelength division multiplexer.

[0048] F2. A wavelength selective switch having a plurality of multi-wavelength ports and a common port, the common port having a common optical signal formed from optical signals input to the plurality of multi-wavelength ports; The apparatus of claim F1, wherein each multi-wavelength port is associated with the output of one of the optical amplifiers of the optical module, and the common port is coupled to the transmission fiber.

[0049] F3. The apparatus of F2, further comprising a contention-free wavelength selective switch, the contention-free wavelength selective switch being coupled between the plurality of multi-wavelength ports of the wavelength selective switch and the output of the optical amplifier of each optical module.

[0050] F4. The apparatus described in any one of F2 to F3, wherein the plurality of optical modules comprises N optical modules, and the plurality of multi-wavelength ports includes N multi-wavelength ports, where N is an integer value of 2 or greater.

[0051] F5. The apparatus of any one of F2-F4, wherein the plurality of first input ports comprises M first input ports, where M is an integer value greater than 2 and equal to N.

[0052] F6. The apparatus described in any one of F1 to F5, wherein each of the plurality of optical modules has at least two first arrayed waveguides coupled to two or more of the plurality of first input ports.

[0053] F7. The apparatus of any one of F1-F6, wherein the optical data signals received at each of the plurality of first input ports from each of the plurality of transponders are at different wavelengths.

[0054] F8. An apparatus according to any one of F1 to F7, wherein the spectrally adjacent optical signals include optical signals having center wavelengths within a predetermined continuous spectral bandwidth, the center wavelengths being adjacent to another center wavelength within the predetermined continuous spectral bandwidth.

[0055] F9. The apparatus of any one of F1-F8, wherein each of the plurality of optical modules includes a second arrayed waveguide grating including a plurality of output ports configured to provide transmission data signals received on the transmission fiber to the plurality of transponders.

[0056] F10. The apparatus of F9, wherein the second arrayed waveguide grating includes a second input port that receives the transmit data signal and separates the transmit data signal into individual receive signals for each of the plurality of output ports.

[0057] F11. The apparatus of F10, wherein the second input port is coupled to a plurality of multi-wavelength ports of a wavelength selective switch.

[0058] F12. The apparatus of F11, wherein the plurality of output ports are equal to the plurality of first input ports of the first arrayed waveguide grating.

[0059] F13. A colorless splitter / combiner, the colorless splitter / combiner having a plurality of colorless input ports and a common port, the common port having a common optical signal formed from the optical signals input to the plurality of multi-wavelength ports; The apparatus described in F2, wherein one of each colorless input port is associated with the output of the optical amplifier of one of the optical modules, and the common port is coupled to the transmission fiber.

[0060] F14. The apparatus of F1, wherein the plurality of first input ports comprises M first input ports, where M is an integer value greater than 2 and not equal to N.

[0061] F15. An optical module for a wavelength division multiplexer or demultiplexer, comprising: a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; 11. An optical module, further comprising an optical amplifier having an output and an input, the input of the optical amplifier coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

[0062] F16. The optical module of F15, comprising a second arrayed waveguide grating, the second arrayed waveguide grating including a plurality of output ports configured to provide transmission data signals received on the transmission fiber to the plurality of optical transponders.

[0063] F17. An optical module described in any one of F15 to F16, wherein the second arrayed waveguide grating includes a second input port that receives the transmission data signal and separates the transmission data signal into individual received signals for each of the multiple output ports.

[0064] F18. The optical module according to any one of F15 to F17, wherein the second input port is coupled to a plurality of multiple wavelength ports of a wavelength selective switch.

[0065] F19. The optical module according to any one of F16 to F18, wherein the plurality of output ports are equal to the plurality of first input ports of the first arrayed waveguide grating.

[0066] F20. A system comprising: A plurality of transponders; A transmission fiber; a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of the plurality of transponders for transmission on the transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; the plurality of optical modules are configured such that spectrally adjacent optical signals are mapped to corresponding first input ports on different optical modules of the plurality of optical modules; each optical module having an optical amplifier having an output and an input, the input of the optical amplifier coupled to receive the combined signal from the first output port of the first arrayed waveguide grating; system.

[0067] F21. A process of mapping spectrally adjacent optical signals received from a transponder (or transmitted from a corresponding first input port to a transponder) to a corresponding first input port of a different one of a plurality of wavelength division multiplexing / non-multiplexing optical modules implemented according to the optical module features of any one of F1 to F20.

[0068] Although the technology herein has been described with reference to particular examples, it should be understood that these examples are merely illustrative of the principles and applications of the disclosed technology. It should therefore be understood that many modifications may be made to the illustrative examples and other configurations may be devised without departing from the scope of the technology as defined by the appended claims. For example, the disclosed technology may be used by reconfigurable optical add-drop multiplexers (ROADMs) or more generally in WDM networks to provide colorless, non-directional, and / or contention-free routing of optical signals between a source and a destination.

[0069] Unless otherwise stated, the foregoing alternatives are not mutually exclusive, but may be implemented in various combinations to realize unique advantages. Because these and other variations and combinations of the above features may be utilized without departing from the subject matter defined by the claims, the above description should be construed as illustrative, and not limiting, of the subject matter defined by the claims. Furthermore, the provision of examples described herein, and phrases such as "such as" and "including" should not be construed as limiting the subject matter of the claims to any particular examples, but rather the examples are intended to illustrate only some, but not all, possible variations of the disclosed technology. Furthermore, the same reference numbers in different drawings may identify the same or similar elements.

Claims

1. 1. A wavelength division multiplexing device, comprising: a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; the plurality of optical modules are configured such that spectrally adjacent optical signals are mapped to corresponding first input ports on different optical modules of the plurality of optical modules; a first output port of the first arrayed waveguide grating and a second output port of the second arrayed waveguide grating, the first output port being coupled to the second output port of the first arrayed waveguide grating;

2. a wavelength selective switch having a common port and a plurality of multiple wavelength ports, the common port having a common optical signal formed from optical signals input to the plurality of multiple wavelength ports; 2. The apparatus of claim 1, wherein each multi-wavelength port is associated with the output of one of the optical amplifiers of the optical modules, and the common port is coupled to the transmission fiber.

3. 3. The apparatus of claim 2, comprising a contention-free wavelength selective switch coupled between the plurality of multi-wavelength ports of the wavelength selective switch and the output of the optical amplifier of each optical module.

4. 3. The apparatus of claim 2, wherein the plurality of optical modules comprises N optical modules, and the plurality of multi-wavelength ports includes N multi-wavelength ports, where N is an integer value greater than or equal to two.

5. The apparatus of claim 4 , wherein the plurality of first input ports comprises M first input ports, where M is an integer value greater than 2 and equal to N.

6. 2. The apparatus of claim 1, wherein the plurality of first input ports comprises M first input ports, where M is an integer value greater than 2 and not equal to N.

7. 2. The apparatus of claim 1, wherein each of the plurality of optical modules comprises at least two first arrayed waveguides coupled to two or more of the plurality of first input ports.

8. 2. The apparatus of claim 1, wherein the optical data signals received at each of the first plurality of input ports from each of the transponders are at different wavelengths.

9. 2. The apparatus of claim 1, wherein the spectrally adjacent optical signals comprise optical signals having center wavelengths within a predetermined contiguous spectral bandwidth, the center wavelengths being adjacent to another center wavelength within the predetermined contiguous spectral bandwidth.

10. 10. The apparatus of claim 1, wherein each of the plurality of optical modules includes a second arrayed waveguide grating including a plurality of output ports configured to provide transmission data signals received on the transmission fiber to the plurality of transponders.

11. 11. The apparatus of claim 10, wherein the second arrayed waveguide grating includes a second input port that receives the transmit data signal and separates the transmit data signal into separate receive signals for each of the plurality of output ports.

12. The apparatus of claim 11 , wherein the second input port is coupled to a plurality of multi-wavelength ports of a wavelength selective switch.

13. The apparatus of claim 10 , wherein the plurality of output ports are equal to the plurality of first input ports of the first arrayed waveguide grating.

14. a colorless splitter / combiner having a plurality of colorless input ports and a common port having a common optical signal formed from the optical signals input to the plurality of multi-wavelength ports; 3. The apparatus of claim 2, wherein one of each colorless input port is associated with the output of the optical amplifier of one of the optical modules, and the common port is coupled to the transmission fiber.

15. 1. An optical module for a wavelength division multiplexer or demultiplexer, comprising: a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; a first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of a plurality of optical transponders for transmission over a transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; 11. An optical module, further comprising an optical amplifier having an output and an input, the input of the optical amplifier coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

16. 16. The optical module of claim 15, further comprising a second arrayed waveguide grating, the second arrayed waveguide grating including a plurality of output ports configured to provide transmission data signals received on the transmission fiber to the plurality of optical transponders.

17. 17. The optical module of claim 16, wherein the second arrayed waveguide grating includes a second input port that receives the transmission data signal and separates the transmission data signal into individual receive signals for each of the plurality of output ports.

18. The optical module of claim 17 , wherein the second input port is coupled to a plurality of multi-wavelength ports of a wavelength selective switch.

19. 17. The optical module of claim 16, wherein the plurality of output ports are equal to the plurality of first input ports of the first arrayed waveguide grating.

20. 1. A system comprising: A plurality of transponders; A transmission fiber; a plurality of optical modules, each optical module having a first arrayed waveguide grating, the first arrayed waveguide grating including a first output port and a plurality of first input ports, each of the plurality of first input ports configured to receive an optical data signal from one of the plurality of transponders for transmission on the transmission fiber, the first output port outputting a combined signal formed from the optical data signals received from the plurality of transponders; the plurality of optical modules are configured such that spectrally adjacent optical signals are mapped to corresponding first input ports on different optical modules of the plurality of optical modules; each optical module having an optical amplifier having an output and an input, the input of the optical amplifier coupled to receive the combined signal from the first output port of the first arrayed waveguide grating.

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