MULTIPLE CHANNEL OPTICAL TRANCEIVER MODULES WITH COMPATIBILITY FEATURES
Optical transceiver modules with multiple channel connection with connectors on a motherboard of a line card for network devices, such as a switch, router, crossconnect and the like, are presented. The modules have staggered electronic boards which can engage the connectors which are laterally displaced on the motherboard. The connectors are also arranged so that one of them can engage an optical transceiver module in an SFP connection so that the motherboard connectors are compatible with multiple channel and single channel (SFP) connections.
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The present invention is a continuation-in-part of U.S. patent application Ser. No. 10/847,948, entitled “MULTIPLE CHANNEL OPTICAL TRANSCEIVER MODULES”, filed on May 17, 2004, and assigned to the present assignee.
BACKGROUND OF THE INVENTIONThe present invention is related to optical transceiver modules and their connections. More specifically, the invention is related to optical transceiver modules with multiple channels including a dual row pattern of optical emitters/detectors and separate transmit and detect electronics and connections which are adapted to such multiple channel, optical transceiver modules, as well as currently single channel, optical transceiver modules.
As fiber optics developed, many new technologies emerged to enhance their use. For example, fairly recently, a specification for a new generation of optical modular transceivers was developed named “small form-factor pluggable” (SFP). SFP transceivers are designed to be high bandwidth, small physical size and easily changeable (including being hot-swappable) on the line card of a network device.
Unfortunately, integrated circuit (e.g., application specific integrated circuit or ASIC) densities have increased to the point that line cards are now optical port density limited, rather than switch or processor limited. Thus, the electronics on the motherboards of the line card have the capacity to process more optical information than is currently being transmitted and received from the optical ports of the line card. This extra capacity is potential bandwidth that is not being realized. As a result, many line cards that use conventional SFP optics have unused bandwidth.
There have been many attempts to achieve higher optical port densities. For example, parallel ferrule connectors have been utilized to solve the problem of optical port density on the line card faceplate. However, this typically requires fanout cables that are bulky, expensive and may be unreliable.
Single-mode parallel solutions are available, but they have typically been very large, expensive and difficult to manufacture. Additionally, they may require permanently attached fiber pigtails due to alignment requirements.
As a solution to solve the high cost of these early parallel offerings, the parallel vertical cavity self emitting laser (VCSEL) technology was developed. However, VCSEL technology blossomed at shorter wavelengths (e.g., 850 nm) and enabled only very short multi-mode applications. Also, the majority of VCSEL based parallel optics are designed for parallel data transfer, where all channels of data are synchronous or plesiochronous. These products, therefore, typically do not allow multiple channels that are totally independent (e.g., four independent, serial data channels). Lastly, the reliability of this solution is still questionable.
It would be beneficial to have innovative techniques for providing optical transceiver modules that provides multiple channel optics without the disadvantages normally associated with this capability. Additionally, it would be beneficial if the optical and electrical crosstalk is reduced or eliminated.
BRIEF DESCRIPTION OF THE DRAWINGS
In the description that follows, the present invention is described with reference to embodiments that are used in association with multiple channel optical transceivers for use with line cards of network devices. However, embodiments of the invention are not limited to any particular version, protocol, environment, application, or implementation. For example, although the invention is described in reference to specific embodiments, the invention can be advantageously applied to many embodiments. Therefore, the description of the embodiments that follows is for purposes of illustration and not limitation.
Furthermore, it should be noted the same reference numerals in different drawings for elements which are identical or similar for ease of explanation.
The opposite end 14 of the optical transceiver module 9 can receive a plug 13. For example, the plug can be an MTP or MPO plug. The plug 13 includes a ferrule 15 that retains and aligns the multiple optical fibers in a cable. As shown, the optical transceiver module 9 can include a latch 17 to assist in retaining the plug 13 in the transceiver module 9 when inserted therein. Other types of plugs and retention mechanisms can be utilized with other embodiments.
The ferrule 15 retains optical fibers so they can interface with corresponding optical emitters and optical detectors in the optical transceiver module 9 in a particular manner described below, according to an embodiment of the present invention. On the other hand,
The optical emitters and detectors within the optical transceiver module are aligned with the optical fibers in the ferrule. For example, a bar that includes both laser diodes and detectors may need to be manufactured for the ferrule patterns of
Furthermore, the additional spacing between the laser diodes and detectors results in reduced optical crosstalk. For example, because the fabrication of every other laser diode or detector 129 can be skipped, the spacing can be 250 microns between adjacent laser diodes and detectors (i.e., both within a row and row-to-row). Additionally, this configuration creates multiple transmit/receive pairs, which makes transitions to duplex fiber cable much easier.
Conventional equipment and settings can be utilized to manufacture these bars. As an example, the equipment for manufacturing bars for the ferrules of
In other embodiments, the optical fibers are dressed out in single lines (e.g., eight single lines). In still other embodiments, mixed pairs and single lines can be present. Thus, the optical fibers can be dressed out in different configurations depending on the application (see also
Now the description turns to further specifics of the optical transceiver module 9 according to the present invention.
The ferrule 15 (e.g., a MTP ferrule) is a part of the cable plug 13 and retains the receiving optical fibers 123 and transmitting optical fibers 125 so they can optically couple to the receiving bar 213 and transmitting bar 211 respectively. Electrical crosstalk within the optical transceiver module 9 is reduced or eliminated because the transmitting and receiving electronics are on separate, parallel boards as shown. Conventional optical transceivers modules include an electronic board with both transmitting and receiving circuitry/components, which facilitates electrical crosstalk.
The ferrule 15 retains the optical fibers and is angled at the end proximal to receiving and transmitting bars 213 and 215, respectively. The orientation of the receiving and transmitting bars to the angle of the ferrule is designed so that light reflected at the aperture of transmitting optical fiber 125 is directed away from the aperture of receiving optical fiber 123. Thus, optical crosstalk can be reduced by the specific orientation of the optical emitters and detectors relative to the angled end on ferrule 15.
With regard to
For example, in one embodiment, a MTO or MTP plug 13 is utilized that fans out into four duplex cables.
Still another embodiment of the present invention is found in the connections between the optical transceiver module 9 and the motherboard 3 of the line card 1.
The electrical and optical connections of the optical transceiver module 9 can remain as described previously; the only differences being the locations of the electronic boards 27A and 27B and connectors 7A and 7B correspondingly. However, an advantage of the arrangement shown in
However, besides the physical compatibility with standard SFP connections, the electrical connections to connectors 7A and 7B must be modified. Since the standard SFP connection handles one bidrectional communication channel, i.e., one receiving signal and one transmitting signal, the electronic board 27A and the corresponding connector 7A which engages the board 27A must carry one receiving and one transmitting signal. For the functional capacity of the previously described multichannel optical transceiver module, the “upper” electronic board 27B and corresponding connector 7B must handle the other three channels, i.e., three receiving and three transmitting signals. Thus the upper electronic board 27B has three extra pins for the additional signal paths, as compared to the electronic boards described earlier. The electrical connections between the electronic boards and the transmitting and receiving bars 211 and 213 must also be correspondingly modified. Cf.
Therefore, while the description above provides a full and complete disclosure of the preferred embodiments of the present invention, various modifications, alternate constructions, and equivalents will be obvious to those with skill in the art. Thus, the scope of the present invention is limited solely by the metes and bounds of the appended claims.
Claims
1. An optical transceiver module for removable mounting to a motherboard, said optical transceiver module comprising:
- a housing open at an end;
- a first electronic board fixed within said housing and having an edge extending toward said open end of said housing;
- a second electronic board fixed within said housing parallel to said first electronic board and having an edge extending toward said open end of said housing beyond said edge of first electronic board;
- whereby upon mounting to said motherboard, said first and second electronic boards of said optical transceiver module engage first and second horizontally staggered connectors fixed to said motherboard so as to make electrical connection with said first and second connectors respectively.
2. The optical transceiver module of claim 1 wherein said first electronic board carries signals of only one communication channel.
3. The optical transceiver module of claim 2 wherein said first electronic board and said first connector are disposed so as to form an SFP connection therebetween.
4. The optical transceiver module of claim 3, wherein said second electronic board carries signals of three communication channels.
5. The optical transceiver module of claim 1 wherein said first electronic board and said first connector are disposed so as to form an SFP connection therebetween.
6. The optical transceiver module of claim 5, wherein said second electronic board carries signals of three communication channels.
7. The optical transceiver module of claim 1 wherein said first electronic board carries signals on a plurality of pins at said first electronic board edge, and said second electronic board carries signals on a plurality of pins at said second electronic board edge, said pluralities of pins of said first and second electronic boards making electrical connections with said first and second connectors respectively when said first and second electronic boards engage said first and second horizontally staggered connectors.
8. The optical transceiver module of claim 1 further comprising a row of a plurality of optical emitters; and a row of a plurality of optical detectors, said row of optical emitters is parallel to said row of optical detectors, both said row of optical emitters and said row of optical detectors both electrically coupled to said first and second electronic boards.
9. The optical transceiver module of claim 8 wherein each optical emitter and detector corresponds to an optical fiber retained in a ferrule of a cable and the orientation of the row of optical emitters and the row of optical detectors is such that light reflected an angled surface of the ferrule at an aperture of an optical fiber corresponding to an optical emitter is directed away from an aperture of an optical fiber corresponding to an optical detector.
10. The optical transceiver module of claim 8, wherein said row of optical emitters comprises four laser diodes and said row of optical detectors comprises four laser detectors.
11. A motherboard connector assembly for removably receiving and electrically connecting an optical transceiver module, comprising
- a first connector mounted to a motherboard; and
- a second connector mounted to said motherboard, said second connector horizontally displaced with respect to said first connector so that an optical transceiver module having a housing open at an end, a first electronic board fixed within said housing and having an edge extending toward said open of said housing, and a second electronic board fixed within said housing and having an edge extending toward said open end of said housing beyond said edge of said first electronic board, engages said first and second connectors with said first and second electronic board respectively;
- whereby an electrical connection is formed between said motherboard connector assembly and said optical transceiver module.
12. The motherboard connector assembly of claim 11 wherein said first connector carries signals for only one communication channel to and from said first electronic board of said optical transceiver module.
13. The motherboard connector assembly of claim 12 wherein said first connector is disposed so to be able to engage an optical transceiver module to form an SFP connection therewith.
14. The motherboard connector assembly of claim 13 wherein said second connector carries signals for three communication channels.
15. The motherboard connector assembly of claim 11 wherein said first connector is disposed so to be able to engage an optical transceiver module to form an SFP connection therewith.
16. The motherboard connector assembly of claim 15 wherein said second connector carries signals for three communication channels.
17. The motherboard connector assembly of claim 11 wherein said first connector has a first slot for engaging said first electronic board of said optical transceiver module and said second connector has a second slot for engaging said second electronic board of said optical transceiver module.
18. The motherboard connector assembly of claim 11 wherein said motherboard is operative for a line card of a network device, said network device selected from the group comprising a switch, router, and crossconnect.
19. An optical transceiver module for removable mounting to a motherboard, said optical transceiver module comprising:
- a housing;
- first means fixed within said housing for making an electrical connection to said motherboard, said first means forming an SFP connection to said motherboard; and
- second means fixed within said housing for making an electrical connection with said motherboard.
20. A motherboard connector assembly for removably receiving and electrically connecting an optical transceiver module, comprising
- a first connector means mounted to a motherboard; and
- a second connector means mounted to said motherboard, said second connector means displaced with respect to said first connector so that an optical transceiver module having a housing open at an end, a first electronic board fixed within said housing and having edge extending toward said open of said housing, and a second electronic board fixed within said housing and having an edge extending toward said open end of said housing beyond said edge of said first electronic board, engages said first and second connector means with said first and second electronic boards respectively to form an electrical connection between said motherboard connector assembly and said optical transceiver module, and so that an optical transceiver module having a housing open at an end and only one electronic board fixed within said housing and having an edge extending toward said open end of said housing engages said first connector means to form an SFP connection between said motherboard connector assembly and said optical transceiver module.
Type: Application
Filed: Feb 10, 2006
Publication Date: Jun 29, 2006
Applicant: CISCO TECHNOLOGY, INC. (San Jose, CA)
Inventors: James Theodoras (Plano, TX), Matthew Heston (Plano, TX)
Application Number: 11/276,045
International Classification: G02B 6/36 (20060101);