WO2016122678A1

WO2016122678A1 - Optical multiplexer

Info

Publication number: WO2016122678A1
Application number: PCT/US2015/014012
Authority: WO
Inventors: Alan L. Goodrum; Kuang-Yi Wu; Michael Renne Ty Tan; Kevin B. Leigh
Original assignee: Hewlett Packard Enterprise Development LP
Current assignee: Hewlett Packard Enterprise Development LP
Priority date: 2015-01-31
Filing date: 2015-01-31
Publication date: 2016-08-04
Anticipated expiration: 2017-07-31

Abstract

An apparatus including an optical multiplexer that includes a plurality of stages to form associated parts of an optical path. The optical multiplexer combines optical signals associated with a plurality of wavelengths along the optical path to form a wavelength-division multiplexing (WDM) signal and a given stage of the plurality of stages diverts optical energy away from the optical path. The apparatus includes a photodetector to sense the diverted optical energy.

Description

OPTICAL MULTIPLEXER

Background

[0001 ] Wavelength-division multiplexing (WDM) may be used to communicate several data channels over a single optical fiber. With WDM, each data channel corresponds to a different wavelength.

[0002] To transmit a WDM optical signal to an optical fiber, laser sources of a WDM optical multiplexer are controlled by corresponding electrical data channel signals to cause the laser sources to produce optical signals that correspond to the data channels. The optical multiplexer contains optics to combine the optical signals at different wavelengths that are produced by the laser modulators into the WDM optical signal.

[0003] To recover the data channels, a WDM optical demultiplexer receives the WDM optical signal from the optical fiber, and optics of the optical demultiplexer separate the WDM optical signal according to wavelength to produce optical signals that correspond to the different data channels. Photodetectors of the demultiplexer sense the optical signals produced by the optics to produce corresponding electrical data channel signals.

Brief Description of the Drawings

[0004] Fig 1 A is a schematic diagram of a computer system according to an example implementation.

[0005] Fig 1 B is a schematic diagram of a network interface according to an example implementation.

[0006] Fig. 2 is a schematic diagram of an optical multiplexer of the network interface of Fig. 1 B according to an example implementation.

[0007] Fig. 3A is a schematic diagram of a zig-zag optical multiplexer assembly according to an example implementation.

[0008] Fig. 3B is a schematic diagram of a zig-zag optical demultiplexer assembly according to an example implementation. [0009] Fig. 4 is a flow diagram depicting a technique to sense the optical power of data channels of an WDM optical signal according to an example implementation.

[0010] Fig. 5 is a schematic diagram of an apparatus according to an example implementation.

[001 1 ] Fig. 6 is a schematic diagram of an optics portion of a bus optical multiplexer assembly according to an example implementation.

[0012] Fig. 7 is a schematic diagram of a zig-zag optical multiplexer assembly according to a further example implementation.

[0013] Fig. 8 is a schematic diagram of a system according to an example implementation.

Detailed Description

[0014] Electrical-optical transceivers may include multiplexers that are used for purposes of multiplexing multiple optical wavelengths onto a single optical fiber so that multiple data channels may be communicated over the fiber. In this manner, for purposes of transmitting data to the optical fiber, a transmitter of the transceiver contains an optical multiplexer, which, in response to electrical data channel signals, generates a wavelength-division multiplexing (WDM) optical signal that is provided to the optical fiber. The WDM optical signal contains a set number of wavelengths, where each wavelength corresponds to one of the data channels. For purposes of receiving data from the optical fiber, a receiver of the transceiver contains an optical demultiplexer, which, in response to a WDM optical signal that is received from the optical fiber, generates electrical signals that correspond to the data channels of the received WDM optical signal.

[0015] In accordance with example implementations that are described herein, the optical multiplexers and demultiplexers are constructed to perform a specific type of WDM called "coarse wavelength-division multiplexing (CWDM)," in which the number of data channels are equal to or less than eight. However, in accordance with further example implementations, optical multiplexers and demultiplexers may be

constructed to perform WDM for more than eight wavelengths. [0016] In accordance with the systems and techniques that are disclosed herein, an optical multiplexer is constructed to add a data management channel to the WDM optical signal. In other words, the WDM optical signal that is generated by the optical multiplexer contains wavelengths that correspond to the data channels and an additional wavelength that corresponds to a data management channel. In general, the data management channel is an out-of-band, or sideband, channel that contains data pertaining functions related to network equipment and data channel management. In this manner, the data management channel, in accordance with example implementations, is a supervisory channel, which may communicate provisioning data, network management messaging data, alarm data, and so forth.

[0017] In accordance with example implementations, the data management channel and a set of associated data channels are communicated on a single optical fiber (i.e., communicated using a data management wavelength and multiple data channel wavelengths on a single optical fiber); and the data management channel contains information pertaining to how the wavelengths of the associated data channels are used. As examples, the data management channel may communicate information describing assignment/reassignment of data channel wavelengths;

information identifying one or multiple data channel wavelengths as being turned off, or not being used; information describing destinations of the data channels at the receiving end of the optical fiber; and so forth.

[0018] Among the possible benefits of having an out-of-band (by using different wavelength) but in-fiber, management signal, an in-fiber management signal may notify a receiver about wavelength presence or usage. In this manner, all or some of the data wavelengths may be absent for many reasons, such as power conservation, bandwidth scaling per fee, and so forth. Also, the controlling integrated circuit may shuffle input data channels to different wavelengths, and the in-fiber management signal may provide information to the receiving end regarding how the integrated circuit maps the data channels to wavelength to the receiving end, providing another layer of data path switching capabilities, which can be useful for optical switches. [0019] In accordance with example implementations, the data management channel may be arranged to take the longest signal path within the optical multiplexer, i.e., the highest optical signal loss, as compared to the data channels, so that the optical signal performance of the data channels are minimally affected. In other words, the data management channel may be associated with a wavelength, which has an optical loss that is unsuitable for data channel communication (an optical loss near, at or greater than 20 percent, as an example). Furthermore, the wavelength of the data management channel may be smaller than any of the data channel wavelengths. More specifically, in accordance with example

implementations, the data management channel wavelength may be too small to be considered reliable for use for a data channel communication. In this manner, for the relatively larger data channel wavelengths, the substrate (a gallium arsenide (GaAs) substrate, for example) of the laser source (for each channel) may be relatively optically transparent. For smaller wavelengths, such as the wavelength of the data management channel, the substrate may be optically less transparent such that communication using such wavelengths may experience significant losses. Such losses may be tolerated for the data management channel, however, as the data management channel, in accordance with example implementations, may have a significantly lower bandwidth than any of the data channels.

[0020] Systems and techniques are also disclosed herein for purposes of sensing a power of the data channels using a photodetector.

[0021 ] As a more specific example, Fig. 1A depicts a computer system 100 in accordance with example implementations. In general, the computer system 100 includes one or multiple processor-based machines 1 10. In this regard, a given processor-based machine 1 10 may include one or multiple central processing units (CPUs) 1 14, memory 1 16 (semiconductor storage, memristor storage, magnetic- based storage, and so forth) and other hardware, such as one or multiple network interfaces 120. As examples, the processor-based machine 1 10 may be a server, a client, a server blade, a desktop computer, a laptop computer, and so forth, depending on the particular implementation. [0022] The processor-based machine(s), in accordance with example implementations, communicate using optical fiber links, such as depicted optical fiber link 130. For this purpose, the computer system 100 may include one or multiple network switches 140, as well as other components and/or network fabric 150. As depicted in Fig. 1A, the network switch 140 may include one or multiple network interfaces 142 for purposes of communicating with the optical fiber links. Moreover, in accordance with example implementations, the network interfaces 120 and 142 of the computer system 100 communicate over the optical fiber links 130 using CWDM signals. The optical fiber link 130 may include multiple fibers, where each fiber may be used to transport a CWDM optical signal.

[0023] More specifically, in accordance with example implementations, the network interface 120, 142 may have an architecture represented by a network interface 160 of Fig. 1 B. Referring to Fig. 1 B, in general, the network interface 160 includes one or multiple transmitters 164 and one or multiple receivers 170. In accordance with example implementations, the transmitter 164 contains one or multiple optical multiplexers 166. In general, each optical multiplexer 166 combines optical signals associated with multiple data channels (and wavelengths) into a CWDM optical signal (i.e., a multiple-wavelength signal), which is furnished to a corresponding optical fiber of an optical fiber link. Moreover, in accordance with example

implementations, the receiver 170 may contain one or multiple optical demultiplexers 172. In general, each optical demultiplexer 172 receives a CWDM optical signal from a corresponding optical fiber of an optical fiber link, demultiplexes data channels from the CWDM optical signal, and generates electrical signals, which represent data communicated over the data channels.

[0024] Referring to Fig. 2, in accordance with example implementations, the optical multiplexer 166 provides an output CWDM optical signal 220 and includes multiple stages 210 to add data channel wavelengths to the output CWDM optical signal 220. In general, each stage 210 receives an associated optical data channel signal 214 (from a laser source, now shown in Fig. 2), which corresponds to a particular data channel. In accordance with example implementations, the optical data channel signals 214 are n-1 single wavelength signals that are each associated with a different wavelength λι . . . λ_η-ι (where "n" is an integer index); and the stages 210 combine the optical data channel signals 214 to produce an output CWDM optical signal 220 that contains all of the X-_\ to λ_η-ι wavelengths.

[0025] The multiplexer 166 includes another stage 21 1 , which receives an optical data management signal 230 (from a laser source not shown in Fig. 2) that corresponds to another wavelength λ_η and introduces the wavelength λ_η to the output CWDM optical signal 220. As depicted in Fig. 2, the λ_η wavelength may be less than any of the other wavelengths λι to λ_η-ι of the CWDM output signal 220, in

accordance with example implementations. The λ_η wavelength, in accordance with example implementations, is used to communicate data (data representing

messages, for example) for the data management channel.

[0026] The stage, in addition to introducing the data management channel, included in the optical multiplexer 166 also, in accordance with example

implementations, diverts optical energy associated with the data channels to a photodetector 250. In this regard, in accordance with example implementations, the stage 21 1 provides an optical signal 252, which represents the power of the data channels to the photodetector 250; and the photodetector 250 provides a

corresponding channel data power signal 260 (an electrical signal, for example), which represents a measure of the collective power of the data channels.

[0027] Fig. 3A depicts a zig-zag optical multiplexer assembly 300 in accordance with example implementations. The assembly 300 includes an optical multiplexer 324, modulated laser sources 370 (laser sources 370-1 , 370-2, 370-3, 370-4 and 370-5, being depicted as examples in Fig. 3A), a photodetector 390 and an integrated circuit (IC) 303. The optical multiplexer 324, the laser sources 370, the photodetector 390 and the IC 303 may be mounted to a substrate 302, which may, for example, be mounted to a printed circuit board. The IC 303 is electrically coupled to the laser sources 370 to control the optical outputs of the laser sources 370.

[0028] More specifically, each laser source 370 may be associated with a different channel (and corresponding wavelength) of an output CWDM optical signal 350 that is communicated to an optical fiber 310, which is attached to the assembly 300. In this regard, the laser sources 370, in response to electrical signals that are provided by the IC 303, provide corresponding wavelength optical signals that represent data for corresponding channels. For example, the laser source 370-1 is constructed to provide a single wavelength λ₅ optical signal; the laser source 370-1 receives an electrical signal from the IC 303, which is indicative of the data for a corresponding channel; and the laser source 370-1 generates an optical signal that has the λ₅ wavelength and represents the data for the channel.

[0029] The optical multiplexer 324 combines the optical signals that are generated by the laser sources 370 to produce the output CWDM optical signal 350. For the example implementation of Fig. 3A, the optical assembly 324 creates an optical path 330 (called a "zig-zag optical path 330" herein) that extends in a zig-zag fashion inside an optical block 325 of the optical multiplexer 324.

[0030] In addition to the optical block 325, the optical multiplexer 324 includes CWDM filters 360 (five CWDM filters 360-1 , 360-2, 360-3, 360-4 and 360-5, being depicted as examples in Fig. 3A). Each CWDM filter 360 is a wavelength-selective filter that is constructed to receive light, or optical energy, from the zig-zag optical path 330; receive light from an associated laser source 370; allow light near the wavelength of the associated laser source 370 to pass through the filter 360 and into the zig-zag optical path 330; and direct optical energy near the wavelength(s) of the CWDM signal 350 present at that particular point of the zig-zag optical path 330 to another segment of the path 330. The assembly 320 further includes optical redirection surfaces 346 (mirrors, for example) which are disposed at the opposite side of the optical block 325 from the CWDM filters 360 for purposes of directing optical energy to the next CWDM filter 360 along the zig-zag optical path 330.

[0031 ] As depicted in Fig. 3A, the optical block 325, optical redirection surfaces 346, and CWDM filters 360 form stages 342 of the optical multiplexer 324 for purposes of creating the data channels of the CWDM optical signal 350. In this manner, in general, a given stage 342 forms a segment of the zig-zag optical path 330; allows energy at a wavelength associated with a CWDM data channel to enter the optical path 330, and further directs the now-combined wavelength signal to the next stage 342. For example, the initial stage 342 receives optical energy associated with the wavelength λ₅ and directs the optical signal containing the λ₅ wavelength to the next stage 342, which adds energy associated with the λ₄ wavelength before directing the light containing the λ + λ₅ wavelengths to the next stage 342.

[0032] In accordance with example implementations, the wavelength λ₅ of light provided by the laser source 370-1 may correspond to the wavelength of a data management channel. The initial stage 342 of the zig-zag optical path 330 injects the data management channel (and corresponding wavelength λ₅) to form the initial CWDM optical signal 350.

[0033] In accordance with example implementations, in addition to the stages 342, the optical multiplexer 324 includes a stage 375 that follows the stages 342 and forms the final segment of the zig-zag optical path 330. The stage 375 receives the optical energy, or light, from the laser source 370-5. The optical signal from the last laser source 370-5 passes through the CWDM filter 360-5; and the CWDM filter 360- 5 directs the resulting CWDM optical signal to a partially-reflective mirror 363.

[0034] As also depicted in Fig. 3A, the partially-reflective mirror 363, in accordance with example implementations, may be disposed on the same side of the optical block 325 as the surfaces 346. The partially-reflective mirror 363, unlike the surfaces 346, does not fully reflect optical energy from the data channel wavelengths of the CWDM signal. Instead, the mirror 363 is partially transmissive, which allows a diverted optical signal 380 to be communicated to the photodetector 390 for purposes of sensing the collective power in the data channels of the CWDM signal 350.

[0035] Thus, in accordance with example implementations, the surface 363 partially reflects (reflects ten percent, as an example) of the optical energy pertaining to the data channel wavelengths from the zig-zag optical path 330 to the photodetector 390, and allows most of this optical energy (ninety percent, as an example) to pass through the partially-reflective mirror 363 to the optical fiber 310. In accordance with some example implementations, the optical multiplexer 324 may further include a lens and/or other optics for purposes of directing the diverted optical energy to the photodetector 390.

[0036] As also depicted in Fig. 3A, among its other features, the optical multiplexer 324 may include a prism 314 for purposes of directing the optical energy passing through the partially-reflective mirror 363 to the optical fiber 310.

[0037] Other variations are contemplated, which are within the scope of the appended claims. For example, although in the example implementation of Fig. 3A, the data management channel (having wavelength λ₅) is introduced in the first stage 342 of the zig-zag optical path 330, the data management channel may be added in another stage, in accordance with further example implementations. Moreover, although Fig. 3A illustrates a one dimensional array of the laser sources 370 and the corresponding wavelengths λι to λ₅ of a CWDM optical signal 350 entering a single fiber 310, in further example implementations, there may one or more additional arrays of laser sources that are in parallel with the laser sources 370 of Fig. 3A. In this manner, one or more additional arrays of laser sources may be disposed on the substrate 392 in parallel with laser sources 370, and the optical multiplexer assembly may have one or more corresponding zig-zag optical multiplexers to generate an array of CWDM optical signals to enter a corresponding array of fibers.

[0038] Referring to Fig. 3B, in accordance with example implementations, the corresponding stages of a zig-zag demultiplexer assembly 400 having a zig-zag optical path 420 may be arranged in an opposite manner to the assembly 300 depicted in Fig. 3A, in that the demultiplexer 400 may include photodetectors 430 (five photodetectors 430-1 , 430-2, 430-3, 430-4 and 430-5, being depicted in Fig. 3B), with the photodetector 430-1 that is disposed the farthest from the fiber 310 being used to sense the data management channel.

[0039] In accordance with example implementations, as noted above, the data management channel may contain information pertaining to how the wavelengths of the associated data channels are used. Thus, referring to Fig. 4, in accordance with example implementations, a technique 450 includes communicating (block 452) first optical signals associated with wavelengths and data channels to an optical multiplexer and communicating (block 454) a second optical signal associated with another wavelength and a data management channel to the optical multiplexer. The wavelength of the data management channel has an associated optical loss that is greater than twenty percent. The technique 450 includes using (block 456) the optical multiplexer to combine the first and second optical signals to form a wavelength-division multiplexing (WDM) signal. Pursuant to the technique 450, the WDM signal is provided (block 458) to an optical fiber.

[0040] Referring to Fig. 5, thus, in accordance with example implementations, an apparatus 500 includes multiple stages 520 (M stages 520-1 , 520-2. . .520-M, being depicted in Fig. 5) to form associated parts of an optical path 530. The optical multiplexer 510 combines optical signals 518 associated with a plurality of wavelengths along the optical path 530 to form a wavelength-division multiplexing (WDM) signal 540, and a given stage (i.e., stage 520-M for the example

implementation of Fig. 5) of the stages 520 diverts optical energy (as depicted at reference numeral 550) from the optical path 530. A photodetector 560 of the apparatus 500 senses the diverted optical energy 550.

[0041 ] In accordance with further example implementations, an optical multiplexer assembly may combine wavelengths using an optical path other than one that extends in a zig-zag direction. As an example, referring to Fig. 6, a bus optical multiplexer assembly (an optics portion 600 of the bus optical multiplexer assembly being depicted in Fig. 6) may be used in place of the assembly 320 in Fig. 3A. The bus optical multiplexer assembly shares common features with the optical multiplexer assembly 320, with similar reference numerals being used to denote similar components. However, unlike the zig-zag optical multiplexer assembly 320, the bus optical multiplexer assembly includes a bus optical multiplexer 630, which combines the optical signals from the laser sources 370 in a general straight line optical path 620. The bus optical multiplexer includes a series of partially-reflective mirrors 632, which inject different wavelengths into the optical path 620.

[0042] The optical multiplexer 630 includes a final stage that contains a partially- reflective mirror 633 that diverts a portion (ten percent, for example) of the collective optical energy from the CWDM signal to form diverted light 639, which, in turn, is reflected by a reflector, or mirror 650, of the optical block 630, to form corresponding light 640 that is sensed by the photodetector 390. The partially-reflective mirror 633 reflects most of the received light from the optical path 620 (ninety percent, for example) to an output path to form a corresponding CWDM optical output signal 660 for the optical multiplexer assembly 600.

[0043] As compared to the zig-zag optical multiplexer assembly 320, the bus optical multiplexer assembly 600 has a slightly shorter optical path and fewer reflections (less loss, less dispersion). The zig-zag optical multiplexer assembly 320 has the advantages that 1 ) the CWDM filters 360 may be made in one piece, and 2) the optical redirection surfaces 346 may be designed to optimize the beam

divergence.

[0044] Referring to Fig. 7, in accordance with further example implementations, a zig-zag optical multiplexer assembly 700 may be used in place of the zig-zag optical multiplexer assembly 300 of Fig. 3A or the bus optical multiplexer assembly that is depicted in Fig. 6. The optical multiplexer assembly 700 contains similar

components to the optical multiplexer assembly 300 of Fig. 3A, with similar reference numerals being used to denote similar components. However, unlike the optical multiplexer assembly 300, the optical multiplexer assembly 700 includes an optical multiplexer 724 (replacing the optical multiplexer 324), which combines the splitting and CWDM filtering using a wavelength selective filter 710.

[0045] The laser sources 370 are arranged such that the λ₅ wavelength is introduced last in the optical path. In this manner, as depicted in Fig. 7, a stage 702 (replacing stage 375 of assembly 300) which includes the wavelength selective filter 710 receives light from the stage 342 associated with the λ₅ wavelength and allows some (ten percent, for example) of the light to pass through (as depicted at reference numeral 720) to the photodetector 390. The wavelength selective filter 710 also receives light from the laser source 370-5 and allows the associated λ₅ wavelength to pass through the filter 710 and enter the zig-zag optical path 330. The wavelength selective filter 710 directs most (ninety percent, for example) of the received light from the stage 342 as well as the light received from the laser source 370-5 to the prism 314.

[0046] In accordance with example implementations, the λ₅ wavelength is associated with the data management channel and is introduced last into the optical path. However, in further example implementations, the data management channel may be introduced in any of the stages.

[0047] Similar to the optical multiplexer assembly 300 of Fig. 3A, the optical multiplexer assembly 700 may, in accordance with further example implementations, have one or more additional arrays of laser sources that are in parallel with the laser sources 370 of Fig. 3A and one or more corresponding multiplexers so that multiple CWDM signals are provided to multiple optical fibers.

[0048] Thus, the optical multiplexer 724 contains a single element, the wavelength selective filter 710, which serves dual functions as an optical splitter and performs WDM filtering. Although the optical multiplexer assembly 300 has relatively less complex optical components, the reduced number of components of the optical multiplexer assembly 700 may result in the assembly 700 having such advantages as a relatively lower optical power loss and a relatively lower manufacturing cost.

[0049] Referring to Fig. 8, in accordance with example implementations, a system 800 includes a processor 810 and a network interface 820 that is coupled to the processor 810 to communicate data 812 for the processor 810 using data channels over an optical fiber communication link 81 1 . The system 800 includes a network switch 830 that is coupled to the network interface 820. The network interface 820 and/or the network switch 830 includes an optical multiplexer 850 to combine optical signals associated with a plurality of wavelengths and a plurality of the data channels to form a wavelength-division multiplexing (WDM) signal.

[0050] It is noted that the network interface 820 and network switch 830 may contain other components that are not depicted in Fig. 8. For example, in

accordance with example implementations, the network interface 820 and network switch 830 may contain one or multiple optical demultiplexers for purposes of receiving data from optical fiber(s). [0051 ] The optical multiplexer 850 includes a wavelength-selective filter 860. The wavelength-selected filter 860 diverts optical energy away from the WDM signal to form an indication of a power of the data channels; and the wavelength-selective filter 860 adds an optical signal associated with another wavelength and associated with a data management channel to the WDM signal.

[0052] In accordance with example implementations, the data channel wavelengths may be a range of wavelengths from near or at 950 to near or at 1070 nanometers (nm) (data channel wavelengths of 990, 1015, 1040 and 1065 nm, for example) and the data management channel wavelength may be near or at 880 to 900 nm. Other wavelengths may be used, in accordance with further example implementations.

[0053] In accordance with further example implementations, the systems and techniques that are disclosed herein may be used to communicate a wide range of data using WDM optical signaling, such as data for computer systems,

telecommunication systems, video programming systems, and so forth.

[0054] While the present techniques have been described with respect to a number of embodiments, it will be appreciated that numerous modifications and variations may be applicable therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the scope of the present techniques.

Claims

What is claimed is 1 . An apparatus comprising:

an optical multiplexer comprising a plurality of stages to form associated parts of an optical path, wherein the optical multiplexer combines optical signals associated with a plurality of wavelengths along the optical path to form a

wavelength-division multiplexing (WDM) signal and a given stage of the plurality of stages diverts optical energy away from the optical path; and

a photodetector to sense the diverted optical energy.

2. The apparatus of claim 1 , wherein:

the given stage comprises a wavelength-selective filter to allow another optical signal associated with another WDM wavelength to enter the optical path; the wavelength selective filter is positioned to receive light associated with the plurality of wavelengths;

the wavelength selective filter allows a first portion of the received light to be directed to the photodetector; and

the wavelength selective filter directs a second portion of the received light to an output of the optical multiplexer.

3. The apparatus of claim 1 , further comprising:

laser sources to provide the optical signals associated with the plurality of wavelengths,

wherein the plurality of wavelengths are associated with coarse wavelength- division multiplexing (CWDM) data channels.

4. The apparatus of claim 1 , wherein:

the given stage comprises a WDM filter and a splitter;

the WDM filter allows light associated with a wavelength of the plurality of wavelengths to enter the optical path;

the splitter is positioned to receive light associated with the plurality of wavelengths; the splitter allows a first portion of the received light to be directed to the photodetector; and

the splitter directs a second portion of the received light to an output of the optical multiplexer.

5. The apparatus of claim 1 , wherein the optical multiplexer comprises a zig-zag optical multiplexer or a bus optical multiplexer.

6. The apparatus of claim 1 , wherein:

the optical multiplexer comprises filters to introduce the plurality of wavelengths to the WDM signal; and

the plurality of wavelengths comprise wavelengths associated with data channels and a wavelength associated with a data management channel.

7. A method comprising:

communicating a plurality of first optical signals associated with a plurality of wavelengths and a plurality of data channels to an optical multiplexer;

communicating a second optical signal associated with another wavelength and a data management channel to the optical multiplexer, wherein the another wavelength has an associated optical loss greater than twenty percent;

using the optical multiplexer to combine the optical signals to form a wavelength-division multiplexing (WDM) signal; and

providing the WDM signal to an optical fiber.

8. The method of claim 7, further comprising communicating information via the data management channel pertaining to how the wavelengths of the data channels are used.

9. The method of claim 7, further comprising:

using the optical multiplexer to divert optical power from the WDM signal, wherein the diverted optical power represents a power of the data channels.

10. The method of claim 7, further comprising:

using a wavelength selective filter of the optical multiplexer to direct light to a photodetector to form an indication of a power of the data channels and introduce one of the optical signals associated with the data management channel to the WDM signal or one of the data channels to the WDM signal.

1 1 . The method of claim 7, further comprising:

using a WDM filter of the optical multiplexer to add the second optical signal associated with the data management channel to the WDM signal; and

using a splitter of the optical multiplexer to direct light to a photodetector to form an indication of a power of the data channels.

12. The method of claim 7, wherein the plurality of wavelengths associated with the data channels comprise wavelengths in a range of wavelengths from

approximately 950 nanometers to approximately 1070 nanometers, and the wavelength associated with the data management channel comprises a wavelength of approximately 880 to 900 nanometers.

13. A system comprising:

a processor;

an optical fiber communication link;

a network interface coupled to the processor to communicate data for the processor over the optical fiber communication link using data channels; and

a network switch coupled to the network interface,

wherein at least one of the network interface and the switch comprises an optical multiplexer to combine optical signals associated with a plurality of wavelengths and a plurality of the data channels to form a wavelength-division multiplexing (WDM) signal, the optical multiplexer to:

receive light associated with the plurality of wavelengths; allow a first portion of the received light to pass through the optical multiplexer to form an indication of a power of the data channels; and direct a second portion of the received light to an output of the optical multiplexer.

14. The system of claim 13, wherein the optical multiplexer comprises a wavelength selective filter to receive the light associated with the plurality of wavelengths, allow the first portion of the received light to pass through the optical multiplexer to form the indication of a power of the data channels, and direct the second portion of the received light to the output of the optical multiplexer: 15. The system of claim 13, wherein the optical multiplexer comprises:

a WDM filter to add an optical signal associated with a data management channel to the WDM signal; and

a splitter to direct light to a photodetector to form an indication of a power of the data channels.