WO2005050877A1

WO2005050877A1 - Compact optical transceivers for host bus adaptors

Info

Publication number: WO2005050877A1
Application number: PCT/US2004/037792
Authority: WO
Inventors: Greta Light
Original assignee: Finisar Corporation
Priority date: 2003-11-17
Filing date: 2004-11-12
Publication date: 2005-06-02
Also published as: US20050105915A1; US7215889B2

Abstract

In one exemplary implementation, a compact optical transceiver (300) includes a transceiver substrate (205) wherein components are mounted on opposing surfaces of the transceiver substrate (205), and wherein the substrate (205) is shortened. The transceiver substrate (205) is connected to at least one optical subassembly (210, 215) such that the transceiver substrate (205) is perpendicular to the optical subassembly (210, 215). The compact optical transceiver (300) is further mounted to a host bus adaptor (370), such as a host bus adaptor for use in a desktop, laptop, or handheld computer system. In one embodiment, the compact optical transceiver allow a given computer system to internalize connections to an optical network.

Description

COMPACT OPTICAL TRANSCEIVERS FOR HOST BUS ADAPTORS BACKGROUND OF THE INVENTION

The Field of the Invention This invention relates to systems, methods, and computer program products for integrating fiber optic transceivers into computer systems. Background and Relevant Art Fiber optic technology is increasingly employed as a method by which information can be reliably transmitted via a communications network. Networks employing fiber optic technology are known as optical communications networks, and are marked by high bandwidth and reliable, high-speed data transmission. Optical communications networks employ optical transceivers in transmitting information via the network from a transmission node to a reception node. Generally, such optical transceivers implement both data signal transmission and reception capabilities, such that a transmitter portion of a transceiver converts an incoming electrical data signal into an optical data signal, while a receiver portion of the transceiver converts an incoming optical data signal into an electrical data signal. More particularly, an optical transceiver at the transmission node receives an electrical data signal from a network device, such as a computer, and converts the electrical data signal to a modulated optical data signal using an optical traxismitter such as a laser. The optical data signal can then be transmitted in a fiber optic cable via the optical communications network to a reception node of the network. Upon receipt by the reception node, the optical data signal is fed to another optical transceiver that uses a photodetector, such as a photodiode, to convert the received optical data signal back into an electrical data signal. The electrical data signal is then forwarded to a host device, such as a computer, for processing. Generally, multiple components are designed to accomplish different aspects of these functions. For example, an optical transceiver can include one or more optical subassemblies ("OSA") such as a transmit optical subassembly ("TOSA"), and a receive optical subassembly ("ROSA"). Typically, each OSA is created as a separate physical entity, such as a hermetically sealed cylinder that includes one or more optical sending or receiving components, as well as electrical circuitry for handling and converting the optical signals. Within the optical transceiver, each OSA generally includes electrical connections to various additional components such as a transceiver substrate, sometimes embodied in the form of a printed circuit board ("PCB"). OSAs in a conventional transceiver are generally connected to the transceiver substrate in the same horizontal plane, such that the transceiver substrate is parallel to a longitudinal axis defined by the length of a given OSA main body. The transceiver substrate can include multiple other active circuitry components particularly designed to drive or handle electrical signals sent to or returning from one or more of the OSAs. Accordingly, such a transceiver substrate will usually include a number of electrical transmission lines with the one or more OSAs. Such connections may include "send" and "receive" data transmission lines for each OSA, one or more power transmission lines for each OSA, and one or more diagnostic data transmission lines for each OSA. These transmission lines are connected between the transceiver substrate and the OSA using different types of electrical connectors, examples of which include an electrical flex circuit, a direct mounting connection between conductive metallic pins extending from the OSA and solder points on the PCB, and a plug connection that extends from the PCB and mounts into electrical extensions from an OSA. Recent manufacturing standards such as the small form factor ("SFF"), small form factor pluggable ("SFP"), and gigabit small form factor ("XFP") standards have helped improve standards for reducing the overall size of optical transceivers. Unfortunately, the size of most optical transceivers, even under the new manufacturing standards, best suits them for external connections to a computer system, such as a desktop computer, a laptop computer, or a handheld digital device, rather than internal connections. For example, an SFF or SFP optical transceiver may provide an interface between an optical cable and a standard network cable, such as an Ethernet cable, for example, that plugs into a computer system. Alternatively, the optical transceiver may be mounted in a network panel that includes multiple optical transceivers, the panel including an external connection to a computerize system. As presently designed, the amount of components, the orientation, and the size of even SFF or SFP optical transceivers makes it difficult if not impossible to integrate an optical transceiver into very small spaces, such as with a pluggable card in a laptop computer or hand held device. For example, despite its relatively compact nature, a conventional SFF, SFP, or XFP optical transceiver body is still too wide or tall to fit within a typical PCMCIA laptop envelope. Furthermore, even if the conventional optical transceiver could fit within such an envelope, the length of the conventional optical transceiver SFF, SFP, or XFP optical transceiver would take up too much valuable space on the HBA, the space being better suited for other components and circuitry. This makes the conventional optical transceiver less than ideal for internalized use in a computer system. Unfortunately, present manufacturing standards have not suggested ways for making an optical transceiver smaller than already available. This is likely due in part to present manufacturing constraints that require a minimum number of active and passive circuitry components to be present on a transceiver substrate for effective operation. Other constraints along similar lines relate to engineering limitations, such that miniaturization of transceiver components becomes evermore complicated as components and mounting surfaces become smaller. One will also appreciate that increased manufacturing and engineering difficulty also translates into higher costs. Accordingly, what is needed are compact, optical transceivers that can fit within smaller spaces, and can be implemented within compact components such as an HBA, while maintaining compliance with established standards, all at lower costs. BRIEF SUMMARY OF AN EXEMPLARY EMBODIMENT OF THE INVENTION In general, exemplary embodiments of the present invention relate to compact optical transceivers that can be implemented with host bus adaptors (HBA), or other components, in smaller spaces than would otherwise be possible under present manufacturing standards. In particular, one exemplary implementation of an optical transceiver combines standard transceiver OSAs with a compact transceiver substrate that can be mounted in an HBA such as an HBA for use with a desktop computer, a laptop computer, or other similar computer system. In one exemplary implementation, an optical transceiver comprises a transceiver housing, and a transceiver substrate mounted within the transceiver housing. In at least one embodiment, one or more optical sub-assemblies connect to the transceiver substrate in substantially perpendicular fashion via electrical connection points extending from the OSAs into a surface of the transceiver substrate. Other electrical connection points, such as a lead frame, extend from the transceiver substrate directly into the HBA, such as an HBA for use with a computer system. The transceiver substrate is small enough to fit perpendicularly within a conventional transceiver housing, rather than in the same plane as a length of the conventional optical transceiver. As will be further detailed herein, the various aspects of the invention allow a desktop or laptop computer to access fiber optic network communications through an internal connection, rather than connected through an external interface. These and other aspects of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: Figures 1 A- IB illustrate various aspects of a conventional optical transceiver; Figure 2A illustrates a side perspective view of one exemplary implementation of the present invention; Figure 2B illustrates a top perspective view of one exemplary implementation of the present invention; Figure 2C illustrates a forward facing perspective view of one exemplary implementation of the present invention; Figure 2D illustrates a backward facing perspective view of one exemplary implementation of the present invention; Figure 3 A illustrates a side perspective view of one exemplary implementation of the present invention when assembled as an optical transceiver; Figures 3B-3D illustrate different perspective views of an optical transceiver in accordance with aspects of the present invention when mounted on a host bus adaptor; Figure 4A illustrates a suitable environment for implementing a compact optical transceiver in a desktop computer system; and Figure 4B illustrates a suitable environment for implementing a compact optical transceiver in a laptop computer system. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION Figure 1A illustrates an exemplary embodiment of a compact, optical transceiver. In particular, Figure 1A shows one embodiment of a compact optical transceiver in which space on an HBA may be conserved by inverting a conventional transceiver substrate 205 so that it mounts perpendicularly, rather than horizontally, with an axis defined by the length 250 of the OSA 210. In general, this inverted configuration will entail forming an SFF, SFP, or XFP substrate, as appropriate to become the shorter transceiver substrate 205. Forming a shorter transceiver substrate 205 can comprise modifying an existing transceiver substrate, or forming an appropriately-sized transceiver substrate from scratch, although other manufacturing methods will suffice. In any case, transceiver substrate 205 can also include conductive reception points 203, and connection pins, such as electrical connector pins 207 that can connect into an HBA. Electrical connector pins 207 can be any single or dual row pin header assembly, as well as a lead frame. The manufacturing choice for the type of electrical connector 207 can be based on manufacturing constraints as well as end-user-based preferences. As discussed herein, an OSA will be understood to mean any one of a transmit optical subassembly ("TOSA") or a receive optical subassembly ("ROSA") that can be mounted to a transceiver substrate for use in an optical transceiver. A transceiver substrate will be understood to mean a printed circuit board ("PCB") having electrically conductive elements such as circuit traces for transmitting power and/or communication signals between a component of an OSA and a computer system. In addition, although a transceiver PCB can include any circuitry for driving a given OSA, typically, a transceiver PCB includes components such as a laser driver, memory components, as well as other components for driving bias currents, amplifying signals, and so forth. Figure IB is a top view of an OSA and transceiver combination as shown in Figure 1A, except showing two OSAs, such an OSA 210 and an OSA 215, that can connect into the transceiver substrate 205. As illustrated, exemplary OSAs 210 and 215 connect to transceiver substrate 205 using connection pins 212. In one embodiment, connection pins 212 are conductive elements that provide a conductive interface between a given OSA 210, 215 and a computer system. For example, the connection pins 212 provide a stable physical joint between a given OSA and the transceiver substrate 205. The connection pins 212 also are electrically conductive, and so further provide one or more data transmission and reception connections to electrical components (not shown) within the given OSA. Corresponding reception points 203 on the transceiver substrate 205, in turn, are fitted to receive the connection pins 212, and are further electrically coupled to corresponding data transmission and reception lines, as appropriate. As further depicted, the OSAs 210, 215 are configured to mount to the transceiver substrate 205 in a substantially perpendicular fashion, such that the transceiver substrate 205 is perpendicular to an axis defined by the length 250 of a given OSA. This provides a number of structural benefits. For example, since the transceiver substrate 205 is inverted (i.e., perpendicular), the optical transceiver 300 (see Figure 2A) can be substantially shorter than would otherwise be possible in conventional transceiver configurations. This in turn allows space on an HBA to be conserved. Furthermore, since the OSAs 210 and 215 can mount directly to a surface of the transceiver substrate 205, rather than a substrate edge through, for example, a flex circuit, there is an inherent amount of physical connection stability. In particular, a greater amount of surface area for mounting the OSAs allows the OSAs to better accommodate some of the forces that occur when plugging and unplugging optical cables repeatedly to a given OSA. Figure IC shows a front view of the OSAs 210, 215 when mounted on transceiver substrate 205, where OSA 215 is shown on the left, and OSA 210 is on the right. In one embodiment, OSA 210 is a TOSA, and OSA 215 is a ROSA, although the OSA aπangement can be reversed based on manufacturing or other use-based considerations. Figure IC also shows electrical connection pins 207 mounted on a surface of the transceiver substrate 205. Similar to connection pins 212, the electrical connection pins 207 can provide a conductive mounting interface between the optical transceiver 100 and an HBA or other component. Although only connection pins 207 are shown, other components (not shown) may be implemented on the transceiver substrate such as, but not limited to, "status indicator components" such as light emitting diodes, a laser driver and/or signal amplifier, a cuπent bias driver, volatile and/or non-volatile memory, a thermo-electric cooler ("TEC"), and so forth. Figure ID shows a back view of the optical transceiver depicted in Figure IC, where OSA 210 is now indicated in phantom on the left of the back surface of transceiver substrate 205, and OSA 215 is now indicated in phantom on the right of the back surface of transceiver substrate 205. Connection pins 207 are also shown extending downwardly

from the transceiver substrate 205. As illustrated, the back surface of the transceiver substrate 205 can also be used to mount various components 230 that are in addition to any components or circuitry mounted on the front side. As shown in Figure ID, for example, the back side of the transceiver substrate 205 can also have active and passive circuitry components 230 mounted thereon. In at least one implementation, the components 230 are similar to any components that are mounted on the front side of the fransceiver substrate 205, as described in Figure IC. Such components 230 include any capacitor or resistor components that were not mounted on the front side, in addition to any other integrated circuitry. The ability to mount components on both sides of the transceiver substrate 205 can help the transceiver substrate 205 maintain a compact structure without any meaningful loss in functionality. Moreover, as previously described, this aids space conservation on an HBA. Turning now to Figures 2A-2D the compact nature of the optical transceiver 300 is depicted in accordance with exemplary implementations of the present invention. In particular, Figure 2A illustrates a side perspective view of a compact, optical transceiver 300 when the OSAs 210 and 215, and components 230 are mounted on a transceiver substrate 205, and wherein the substrate 205 is positioned within optical transceiver housing 340, and 350. Housings 340 and 350 provide a clean grabbing point for mounting the transceiver package 300 onto an HBA 370. Figure 2 A also illustrates that a compact form of the optical transceiver 300 includes a cavity 360 within housing 340, such that the cavity forms a fiber optic receptacle for receiving a fiber optic connector. Although optical transceivers can be formed to include any type of optical cable interface, a standard "LC" connector is illustrated herein for the purposes of convenience. In addition, Figures 2B-2D illustrate different perspective views in which the optical fransceiver 300 depicted in Figure 2A is mounted on an HBA 370 via connection pins 207. As disclosed herein, the connection pins 207 that extend from the optical fransceiver 300 can be any type of electrical connector such as a single or dual row pin assembly (not shown), as well as a lead frame assembly. In general, connection pins 207 extend from the transceiver substrate 205, and are configured to fit into one or more corresponding conductive junctions such as reception points 307 on HBA 370. Furthermore, as with the transceiver substrate 205, HBA 370 can be any type of printed circuit board that provides a suitable connector interface with a computer system, such as a peripheral component interconnect (PCI) card having edge connectors 380 that can fit a desktop computer system, a printed circuit board with a serial or parallel port, or such as a suitable Personal Computer Memory Card International Association (PCMCIA) standard card that can slide into a laptop computer system. Figures 2C and 2D show opposing surface views of an embodiment of the optical transceiver 300 mounted on HBA 370. In one aspect of the invention, a face plate 390 is included that provides a suitable physical connection interface for components external to the computer system wherein the HBA 370 is employed. In one implementation, the face plate 390 provides a suitable physical connection interface on a desktop computer when the HBA 370 and optical transceiver 300 are mounted within. In other embodiments, the face plate 390 provides a suitable physical connection interface when the HBA 370 is inserted within a laptop or personal digital assistant ("PDA") system. Accordingly, Figures 3A-3B illustrate exemplary computer system environments in which optical transceiver 300 and HBA 370 are implemented. In one suitable embodiment, a desktop computer system 400 has a component interface panel 410 that includes connection interfaces for peripheral devices such as a monitor, a mouse, a keyboard, USB devices, and other components. The exemplary computer system 400 also includes network connection interfaces 420 such as connection interfaces for an Ethernet cable, and/or a telephone cable. In accordance with an aspect of the present invention, when the optical transceiver 300 is employed in connection with an HBA 370 such as, for example, a PCI card, the computer system 400 also includes a fiber optic connection interface in a similar position as the other network connections 420. For example, desktop computer system 400 can include a face plate surrounding LC optical connections ports 360. In other embodiments, status indicator components such as LEDs are mounted within or beside the optical connection ports 360 so as to be perceptible by a user outside of the face plate 390. A user could then plug a fiber optic cable 460 directly into the desktop computer system 400 In similar fashion, Figure 3B shows a smaller computer system, such as a laptop computer 430, where an optical transceiver 300 and host bus adaptor can slide into an available side port, such as a PCMCIA port. As before, the cavities and/or ports 360 of the optical transceiver 300 can be substantially exposed so that a user can insert fiber optic cables 460 directly into the laptop computer system. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

What is claimed is: 1. An optical transceiver comprising: a transceiver housing including at least one fiber optic receptacle; a transceiver substrate oriented within the transceiver housing such that a surface on which are mounted one or more optical components faces out of the fiber optic receptacle; and at least one optical subassembly mounted perpendicular to an axis defined by a length of the at least one optical subassembly.

2. The optical transceiver as recited in claim 1, wherein one of the at least one optical subassembly comprises one of a transmit optical subassembly and a receive optical subassembly.

3. The optical transceiver as recited in claim 1, further comprising electrical connection pins mounted to the transceiver substrate, the electrical connection pins extending out of the transceiver housing.

4. The optical transceiver as recited in claim 3, wherein the electrical connection pins are inserted into a host bus adaptor.

5. The optical transceiver as recited in claim 4, wherein the host bus adaptor comprises a printed circuit board that is one of a PCI card, and a PCMCIA card.

6. The optical transceiver as recited in claim 1, wherein the transceiver substrate is a printed circuit board having a first surface and a second surface, and wherein one of an active and passive circuitry component is mounted on the first surface, and wherein another of an active and passive circuitry component is mounted on the second surface.

7. The optical transceiver as recited in claim 6, wherein the at least one optical subassembly is mounted on the first surface; and wherein one or more capacitors and one or more resistors are mounted on the second surface.

8. A host bus adaptor comprising: a printed circuit board having one or more connectors for connecting the printed circuit board to a computer system; and an optical transceiver electrically connected to the printed circuit board, the optical transceiver including: a transceiver substrate having a first and a second opposing surfaces on which can be mounted at least one component; and at least one optical subassembly electrically connected perpendicularly to the transceiver substrate, such that the first and the second opposing surfaces of the transceiver substrate are perpendicular to an axis defined by a length of the optical subassembly.

9. The host bus adaptor as recited in claim 8, wherein one of the at least one optical sub-assembly is one of a transmit optical subassembly and a receive optical subassembly.

10. The host bus adaptor as recited in claim 8, wherein the host bus adaptor comprises a printed circuit board for one of a peripheral component interconnect card, and a PCMCIA card.

11. The host bus adaptor as recited in claim 8, wherein one of an active and passive circuitry component is mounted on the first surface, and wherein another of an active and passive circuitry component is mounted on the second surface.

12. A method of manufacturing an optical transceiver comprisin : mounting a transceiver substrate to at least one optical subassembly such that the transceiver substrate is substantially peφendicular to an axis formed by a length of the at least one optical subassembly; mounting at least one circuitry component onto one of a first and a second surface of the transceiver substrate.

13. The method as recited in claim 12, wherein the at least one optical subassembly is one of a transmit optical subassembly and a receive optical subassembly.

14. The method as recited in claim 12, wherein the transceiver substrate is a printed circuit board.

15. The method as recited in claim 12, wherein the at least one circuitry component is one of a capacitor and a resistor.

16. The method as recited in claim 12, further comprising mounting the transceiver substrate and the at least one optical subassembly within a transceiver housing.

17. The method as recited in claim 16, further comprising mounting the optical transceiver on a host bus adaptor.

18. A method of manufacturing an optical device for use in a computer system: connecting at least one optical subassembly to a first surface of a transceiver substrate, wherein a longitudinal axis defined by a length of the at least one optical subassembly is perpendicular to the first surface of the transceiver substrate; and mounting at least one of an active and a passive circuitry component onto the first surface of the transceiver substrate; and connecting the transceiver substrate to a host bus adaptor.

19. The method as recited in claim 18, further comprising mounting at least one of an active and a passive circuitry component to a second surface of the transceiver substrate.

20. The method as recited in claim 18, further comprising inserting the transceiver subsfrate and the at least one optical subassembly into a transceiver housing that includes at least one fiber optic receptacle.