Patent Application
20240272382
Embodiments presented in this disclosure generally relate to integrating a reconfigurable optical add/drop multiplexer (ROADM) into a pluggable module.
An Optical Add/Drop Multiplexer (OADM) is a Wavelength Division Multiplexing (WDM) networking device that permits specific wavelengths in an optical signal to be dropped or added at the device while also allowing other wavelengths to optically pass through the device without requiring termination. OADMs enable wavelength reuse by allowing a wavelength (i.e., a channel or color) to drop from one direction without continuing through the device. However, OADMs generally cannot be modified or reconfigured after deployment, even if traffic volume and patterns need to change.
In contrast, ROADMs can adjust to changing traffic demands. ROADMs enable remote configuration (and reconfiguration) of the channels, and support more than two directions for, e.g., optical mesh-based networking. Like the OADM, the ROADM allows individual wavelengths to add and drop at a site, with the added benefit of being able to adjust the number of channels that are added/dropped versus the number of channels that pass-through the ROADM if traffic patterns change.
However, ROADMs are typically bulky and built from discrete optical components. This makes them expensive to manufacture and are typically formed on large line cards.
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate typical embodiments and are therefore not to be considered limiting, other equally effective embodiments are contemplated.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially used in other embodiments without specific recitation.
One embodiment presented in this disclosure is a pluggable reconfigurable optical add-drop multiplexer (ROADM) that includes a pluggable body and a photonic integrated circuit (PIC) disposed in the pluggable body, the PIC comprising a ROADM.
Another embodiment presented in this disclosure is a system that includes a WDM filter configured to demultiplex a received WDM optical signal into a plurality of sets of channels, and an computing system comprising a plurality of pluggable ROADMs, wherein each of the plurality of pluggable ROADMs is configured to receive a respective set of the plurality of sets of channels from the WDM filter.
Another embodiment presented in this disclosure is as computing system is a a pluggable ROADM comprising a PIC comprising a ROADM and a CPO configured to receive a channel that is being dropped by the pluggable ROADM and provide a substitute channel, to replace the dropped channel, to the pluggable ROADM.
Embodiments herein describe a pluggable module that includes a ROADM implemented in a photonic integrated circuit (PIC). As mentioned above, ROADMs are typically made from discrete optical components, which means they are typically implemented using bulky line cards. However, by implementing the ROADM in a PIC, the ROADM can be placed on smaller, pluggable modules (e.g., a Small Form-factor Pluggable (SFP), External Laser Small Form Factor Pluggable (ELSFP), Quad Small Form factor Pluggable (QSFP), or Octal Small Form Factor Pluggable (OSFP) which can be a hot-pluggable network interface module). In one embodiment, the pluggable module can include other optical components, such as a continuous wave (CW) laser.
The pluggable module can be plugged into a co-packaged optics (CPO) system which can include a CPO where optics and an electrical application specific integrated circuit (ASIC) are on a single packaged substrate. Optical fibers can connect the pluggable module to the optics in the CPO. The CPO can also provide new optical signals to the ROADM in the pluggable module. For example, wavelengths (or channels) that are being dropped can be sent to the CPO which in turn provides new optical signal(s) (e.g., substitute channels) to the ROADM which it then adds to an output optical signal.
The ROADM PIC 125 can be implemented using any type of semiconductor substrate such as silicon, III-V semiconductors, and the like. The embodiments herein are not limited to any particular type of semiconductor, so long as it permits the formation of a ROADM.
The pluggable module 100 illustrates a pluggable body that includes a faceplate 115 that is an external facing side (e.g., an external interface) of the pluggable module 100, in contrast to a blind-mate electro-optic interface 130 which is the internal facing side (e.g., an internal interface) of the pluggable module 100. That is, the blind-mate electro-optic interface 130 is plugged into a receptacle of a computing system while the faceplate 115 is external facing. For example, the faceplate 115 may protrude from the computing system so that the pluggable module 100 can be grabbed and removed from the receptacle in the computing system (e.g., if the pluggable module 100 fails). However, in other embodiments, the faceplate 115 may be recessed into the computing system.
As shown, the faceplate 115 provides an interface for coupling to an input fiber 105 which provides an optical signal to the pluggable module 100. In this example, the received optical signal includes multiple wavelengths (or wavelength ranges or colors) that form different channels of a WDM optical signal. For example, the received optical signal may include 2-40 different wavelengths or channels which each contain different modulated data.
The pluggable body can include an internal fiber or waveguide that forwards the received optical signal from the faceplate 115 to a fiber interface 120A on the PIC 125. This interface 120A can be implemented using any kind of optical coupler such as a grating coupler, butt coupler (e.g., a prong coupler), one or more lenses, and the like which introduce the optical signal into the PIC 125.
The ROADM in the PIC 125 can add and drop wavelengths or substitute channels in the received WDM optical signal while the remaining, unremoved wavelengths can pass through unaffected. Moreover, the ROADM can adjust or change the add/drop vs. pass-through configuration if traffic patterns change. For example, at one point of time, the ROADM in the PIC 125 may replace two of the wavelengths or channels in the optical signal with two new substitute channels at the same wavelengths. However, at a second point of time, the ROADM can be configured such that it replaces three of the wavelengths or channels with three new channels at the same wavelengths. Or the ROADM can be configured such that it does not replace any of the wavelengths or channels, in which case the received optical signal passes through the PIC 125 having the same channels that it had when it was received. The details of the ROADM in the PIC 125 are discussed in more detail in
The PIC 125 also includes a fiber interface 120B for transmitting wavelengths or channels that are being dropped from the optical signal and receiving new substitute channels at the same wavelengths. This interface 120B can be implemented using any kind of optical coupler such as a grating coupler, a butt coupler, one or more lenses, and the like which couple to internal fibers or waveguides in the pluggable module 100. For example, if the ROADM is currently configured to drop two channels, these two channels are forwarded by the fiber interface 120B to the blind-mate electro-optic interface 130, which is in turn coupled to a drop fiber 135.
The drop fiber 135 can be connected to some other optical and/or electrical component in the computing system containing the pluggable module 100, such as the CPO which is discussed in
As an example, assume the optical signal received at the input fiber 105 includes 10 different wavelengths or channels. The ROADM may drop two of those channels and receive two new substitute channels at the same wavelength. The ROADM adds the two new channels (which have the same wavelengths as the dropped channel but contain different modulated data) to the other eight wavelengths or channels that were not dropped. The pluggable module 100 then forwards a resulting optical signal on the output fiber 110 that, like the received optical signal, has ten wavelengths or channels where two of the channels have new data but the other eight channels have the same data that was in the optical signal received on the input fiber 105.
In one embodiment, the pluggable module is a SFP. In one embodiment, the pluggable module 100 is hot-pluggable where it can be inserted into a computing system when the computing system is currently powered on and without requiring the computing system to be rebooted (e.g., hot swapping). In one embodiment, the pluggable module has a maximum width 40 mm, a maximum length of 116 mm, and a maximum height of 13 mm. In one embodiment, the pluggable module has a width between 13-40 mm, a length between 45-116 mm, and a height between 8.5-13 mm
As a non-limiting example, assume that the pluggable module 100 is installed at a site in City A that is along an optical link between City B and City C. The optical signal (having ten channels) may be sent by City B on the optical link towards City C. However, before reaching City C, the optical signal is first received by the pluggable module 100 at City A. The optical signal may include 2 channels having data destined for locations at City A while the other 8 channel have data destined for locations in City C. The ROADM PIC 125 can remove the two channels that have data for City A but permit the other 8 channels for City C to remain in the optical signal. Further, the ROADM can add two substitute channels (at the same wavelength of the dropped channels) that can have data to be transferred from sources in City A to destinations in City C. Thus, when the optical signal arrives at City C, it now contains two channels containing data sent by sources in City A to destinations at City C and eight channels containing data sent by sources in the City B to destinations at City C.
Also, because the ROADM can be adjusted, as traffic demands change so can the number of wavelengths or channels that are added/dropped by the ROADM PIC 125. For example, if there is less traffic flowing between City B and City A, the ROADM can be reconfigured to drop only one channel so that the other nine channels in the optical signal can be used to transfer data from sources in City B to destinations in City C.
While
Moreover, new or substitute wavelengths or channels 210 are received from the add fiber 140 at the switches 215G and 215H. The two switches 215G and 215H forward the new wavelengths or channels, and the other four switches 2151-L forward the remaining four unremoved wavelengths or channels, to respective variable optical amplifiers (VOAs) 220. While optional, the VOAs 220 permit the ROADM to individually amplify the wavelengths or channels. This may provide greater flexibility where some wavelengths may need more or less amplification than other wavelengths or channels.
The amplified channels are then sent to a multiplexer (mux) 225 which performs WDM to recombine the six wavelengths or channels 210 into a single WDM optical signal which is the forwarded to a next hop in the optical link by the output fiber 110.
The optical components illustrated in
The pluggable module 300 also includes lasers 305. In one embodiment, the lasers 305 can be continuous wave (CW) lasers that generate CW optical signals which then can be modulated by an external component to include modulated data. The lasers 305 can create a significant amount of heat, and as such, it has become common to dispose laser sources such as the lasers 305 in pluggable modules 300 which are at a periphery of a computing system where it is easier to cool the lasers 305. Moreover, the lasers 305 can fail more often than other components. Thus, placing the lasers 305 in the pluggable module 300 means they can easily be replaced by removing the non-functioning module 300 and plugging in a new module 300.
While
As discussed above, the pluggable module 300 receives a WDM optical signal from the input fiber 105 which is then processed by the ROADM PIC 125. One or more of the channels in the WDM optical signal can be dropped and transmitted to a CPO 401. In one embodiment, the CPO 401 is a heterogeneous integration of optics and silicon (e.g., an electrical ASIC) on a single packaged substrate. The CPO 401 can include fiber optic components, digital signal processing (DSP) components, switch ASICs, integrated packaging, and test features. In this example, the CPO 401 includes optical components 402 and an electrical ASIC 403. The optical components 402 can include optical interfaces for connecting to optical fibers that communicate optical signals between the CPO 401 and the pluggable modules 300 and 410. The optical components 402 can also include shapers, splitters, waveguides, optical amplifiers, modulators, photodiodes, and the like.
The electrical ASIC 403 may be an Ethernet switch ASIC. For example, the optical components 402 may convert the optical signals received from the drop fiber 135 (e.g., the dropped wavelengths or channels) into electrical signals which are then sent to an analog front end of the electrical ASIC 403. The ASIC 403 can then process the electrical signals.
To add substitute wavelengths or channels to replace the dropped channels, the electrical ASIC 403 can generate control signals for an optical modulator in the optical components 402 which modulates a CW optical signal received on the CW fiber 310. This substitute optical signal can then be transmitted using the add fiber 140 so it is added to the WDM signal generated by the ROADM PIC 125 as discussed above.
The CPO 401 can also use the CW optical signal generated by the lasers 305 to generate data optical signals which are then transmitted by data fibers 405 to a blind-mate interface of the pluggable module 410. Unlike the pluggable module 300, the pluggable module 410 may not include a ROADM PIC 125 or lasers 305. Instead, the pluggable module 300 may be used to transmit the data optical signals to other computing systems.
Moreover, by using the external WDM filter 515, the ROADMs in the PICs 505 do not need the demux 205 and the mux 225 as discussed in
Alternatively, using the pluggable fiber amplifier 605 can mean the VOAs in the ROADM PICs 505 can be omitted. Thus, the ROADMs in the PICs 505 could be smaller, or could be less costly.
In another embodiment, rather than amplifying the WDM optical signal after it has passed through the ROADM PICs 505 and then been recombined by the WDM filter 515, the input fiber 105 could instead be coupled to the pluggable fiber amplifier 605 so that the received WDM signal is amplified before being forwarded to the WDM filter 515 where the wavelengths are then separated and transmitted to the pluggable modules 510. Again, the ROADM PICs 505 can also include VOAs for individually amplifying the channels, or they may not. The channels can then be recombined by the WDM filter 515 and output on the output fiber 110 without passing through the pluggable fiber amplifier 605 a second time.
In the current disclosure, reference is made to various embodiments. However, the scope of the present disclosure is not limited to specific described embodiments. Instead, any combination of the described features and elements, whether related to different embodiments or not, is contemplated to implement and practice contemplated embodiments. Additionally, when elements of the embodiments are described in the form of “at least one of A and B,” or “at least one of A or B,” it will be understood that embodiments including element A exclusively, including element B exclusively, and including element A and B are each contemplated. Furthermore, although some embodiments disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the scope of the present disclosure. Thus, the aspects, features, embodiments and advantages disclosed herein are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).
As will be appreciated by one skilled in the art, the embodiments disclosed herein may be embodied as a system, method or computer program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, embodiments may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for embodiments of the present disclosure may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
In view of the foregoing, the scope of the present disclosure is determined by the claims that follow.
