WO2020247884A1

WO2020247884A1 - Fiber optic connector, optical transceivers, and transceiver modules and devices

Info

Publication number: WO2020247884A1
Application number: PCT/US2020/036507
Authority: WO
Inventors: Joseph Christopher Coffey; John Charles CHAMBERLAIN
Original assignee: Commscope Technologies Llc
Priority date: 2019-06-07
Filing date: 2020-06-05
Publication date: 2020-12-10

Abstract

A fiber optic connector acts as a heat sink when in contact with an optical transceiver. The connector may include thermal dissipation elements including fins. The heat dissipation elements can be incorporated into the fiber cable itself, the connector strain relief boot, and/or the connector body extending outside of the optical transceiver. A connector and module is provided where the optical connector includes a thermally conductive material to move heat away from the module and dissipate the heat into the ambient air or other medium. The coupling can be between TOSA or ROSA sleeves and the body of the SFP, XFP, QSFP or other transceiver device.

Description

FIBER OPTIC CONNECTOR OPTICAL TRANSCEIVERS AND TRANSCEIVER

MODULES AND DEVICES

Cross-Reference to Related Application

This application is being filed on June 5, 2020 as a PCT International Patent Application and claims the benefit of U.S. Patent Application Serial No.

62/858,882, filed on June 7, 2019, the disclosure of which is incorporated herein by reference in its entirety.

Background

Fiber optic transceivers convert telecommunications signals from electrical to optical and optical to electrical. Fiber optic transceivers require heat sinking or other devices in order to dissipate heat from the electrical to optical and optical to electrical conversion devices within the transceiver housing. Heat must be dissipated in order to maintain the integrity of the semiconductor that is in the transceiver and to maintain performance characteristics such as center wavelength of the optical output, output wattage, and/or lack of modulation distortion.

In addition, it is known to provide the optical transceiver with a module mountable into a cage within the housing for ease of replacement or upgrade. The cage is in these arrangements is mounted on a PCB or other structure within the housing.

As these transceivers are being designed to be in smaller packages for increased density of the equipment and also with higher processing speeds, heat must be dissipated away from the processing silicon to prevent the resulting problems due to the heat. In one example, a heat sink may be placed on top of the cage, within the housing. The heat sink may have fins or other structures to increase surface area.

Improvements are desired.

Summary

A fiber optic connector is provided that acts as a heat sink when in contact with an optical transceiver. The connector can be made of a thermally conductive material. The connector may also include other thermal dissipation elements including fins, or other structures. The heat dissipation elements can be incorporated into the fiber cable itself, the connector strain relief boot, and/or the connector body extending outside of the optical transceiver.

A fiber optic connector that aligns with the optical fiber in the transceiver with the optical fiber in a cable is employed. Connectors can be made of highly dimensionally stable thermoplastic material that is in physical contact with the transceiver when applied. In the present invention, the material is also conductive to heat. Metal constructions are also possible.

An advantage to this design is that space is created behind the housing or panel where the cage heat sink is typically located for a more dense panel. Also, the heat dissipation is moved into open air for more effective dissipation.

An optical connector and module is provided where the optical connector includes a thermally conductive material to move heat away from the module and dissipate the heat into the ambient air or other medium. The coupling would be between the TOSA or ROSA sleeves as well as the body of the SFP, XFP, QSFP or other transceiver device.

Brief Description of the Drawings

Figure l is a perspective view showing an optical to electrical conversion device including two example SFP modules, each one including a TOSA device and a ROSA device;

Figure 2 is a similar view to Figure 1, of another optical to electrical conversion device including two example SFP modules, each one including a TOSA device and a ROSA device, and with a cover removed showing the internal circuitry, including the cages surrounding the SFP modules;

Figure 3 shows a schematic representation of the SFP module engaged with the circuitry internal to the optical to electrical device;

Figure 4 shows in exploded form a printed circuit board (PCB), an SFP cage structure, an SFP module, and a fiber optical plug;

Figures 5A and 5B show two different schematic views of a duplex SFP LC transceiver module in the case of low speed SFP in Figure 5B, and in the case of high speed SFP+ in Figure 5B;

Figure 6 shows a schematic view of a TOSA device and a ROSA device mounted to a PCB through leads in the form pin structures;

Figure 7 shows a different arrangement of a TOSA device and a ROSA device mounted with a flex circuit to the PCB, and further showing two fiber optic connectors (LC) connected to the TOSA and ROSA devices respectively, and further showing the SFP body;

Figure 8 shows a view similar to Figure 7 showing the heat transfer direction from the internal structure of the SFP module to the fiber optic connectors;

Figure 9 shows a similar view of Figure 8 in cross-section showing some of the SFP module;

Figure 10 shows in an enlarged view similar to Figure 7 with two fiber optic connectors partially inserted into the SFP module prior to mating with the TOSA and ROSA devices, respectively;

Figure 11 is a view similar to Figure 10 wherein the two fiber optic connectors are fully mated to the TOSA and ROSA devices, respectively;

Figure 12 is a longitudinal view representative of the TOSA and ROSA device mated with a fiber optic connector body including a ferrule;

Figure 13 is similar to Figure 12 and shows an additional sleeve

surrounding the TOSA and ROSA device inside of the connector body;

Figure 14 shows the view of Figure 13, in side view and in exploded form with the connector sleeve separated from the connector body;

Figure 15 shows the connector sleeve and the connector body of Figure 14 mated together ready for reception of the TOSA or ROSA sleeve;

Figure 16 is a top view of an example LC style fiber optic connector that can be manufactured for use with the SFP module;

Figure 17 is a cross-sectional view that longitudinally bisects the fiber optic connector of Figure 16 for illustrating the internal features of the connector;

Figure 18 is a partially exploded view of the connector of Figures 16 and 17 illustrating the front housing, the ferrule assembly, and the ferrule spring of the connector.

Detailed Description

Figure 1 is shows an optical to electrical conversion device 10 including two example transceiver devices or modules 14, 16, extending from a housing 12. Each module 14, 16 is an example SFP type device and includes a TOSA (transmitter) device and a ROSA (receiver) device as will be described below.

Figure 2 is a similar view to Figure 1, of another optical to electrical conversion device 10’ including two example SFP modules 14, each one including a TOSA device and a ROSA device. A top cover of the housing 12’ is removed showing the internal circuitry 20, including the cages surrounding the SFP modules 14. Module 14a is shown partially inserted into its cage 22.

The heat coupling of concern would be between the TOSA or ROSA sleeves as well as the body 24 of the SFP module 14 (or XFP, QSFP or other transceiver device), and a fiber optical plug or connector 40 plugged into the transceiver device 14.

Optical to electrical conversion devices 10, 10’ include electrical signal inputs 18, shown in the examples as coaxial connectors. Optical to electrical conversion devices 10, 10’ also are provided with an electrical power source to effect the conversion of the telecommunications signals.

Figure 3 is a schematic representation of the SFP module 14 engaged with the device circuitry 20 internal to the optical to electrical conversion device 10.

Figure 4 in exploded form without the housing shows a printed circuit board (PCB) 30, two SFP cage structures 22, an SFP module 14, and a fiber optical plug or connector 40.

Figures 5A and 5B show two different schematic views of a duplex SFP LC transceiver module 140 in the case of low speed SFP in Figure 5B, and in the case of high speed SFP+ in Figure 5B.

The optical conversion or transceiver devices/modules 14, 14a, 16, 114,

214 discussed herein generally include a pair of channels, one of which receives electrical signals, converts the electrical signals to optical signals by way of a laser, introduces them into one end of an optical fiber, which then transmits the optical signals to a further telecommunications device. The second channel of the module receives optical signals from an optical fiber connected external to the apparatus and conveys the optical signals to a photo diode or the like which converts them to electrical signals. In the description herein, the apparatus, systems and methods can generally be used in either of the channels, and since their constructions are generally similar, in some instances only one channel is shown in the figures.

The SFP and SFP+ (small form pluggable) and XFP (10 Gigabit small form factor pluggable) optical transceivers are small, compact, and can support data rates beyond 25 Gb/s.

For shorter wavelength applications (850 nm), the transmission distance is generally less than 500 meters and the optical source is usually a vertical cavity surface emitting laser or VCSEL. These devices have very good quantum efficiency and do not generate a tremendous amount of heat (1.2 Watts). They are classed as uncooled devices. However, the heat generated by a large number of SFP devices in a chassis, panel or housing 12, 12’ can be quite substantial especially when the SFP card edges are in ganged blocks.

For longer wavelength applications (1310 nm or 1550 nm), the transmission distance can be 10+ kilometers. In these transceivers, the optical source is either a fabry-perot laser (FP) or a distributed feedback laser (DFB) and a directly modulation laser (DML) or electro absorption modulated laser (EML) configurations. These devices generate in excess of 1.5 W but like the short wavelength transceivers, the sum of heat produced by a high number of these transceivers can be quite substantial. The frequency stability of these devices is highly dependent on device temperature. Heat sinks in combination with thermoelectric devices are used to control device temperature.

However, these take up space.

Both the short and long wavelength devices have an operating temperature range of 0-70 C (32-158 F).

To compensate for accumulated heat, network elements have used forced air cooling to maintain a stable internal temperature inside the chassis, panels, or housings. The upper temperature limit for most network switches is 85 C which isl 5 C higher than most SFP transceivers. In the prior art to ensure that the SFP devices remain cool, heat sinks are added to the top of the SFP card cage to increase mass and surface area in an effort to remove heat from the SFP device. This can be very problematic due to the poor interface (low thermal mass) between the SFP device and the heat sink (for example, non- conductive labels).

Figure 6 shows a schematic view of a TOSA device 60 and a ROSA device 70 mounted to a PCB 72 through leads 74 in the form pin structures, which forms the internal components of a transceiver module (such as an SFP module).

Figure 7 shows a different arrangement of a TOSA device 60 and a ROSA device 70 mounted with a flex circuit 80 to the PCB 82, and further showing two fiber optic connectors 40 (LC type) connected to the TOSA and ROSA devices 60, 70 respectively, and further showing the conductive SFP body 24.

Figure 8 shows a view similar to Figure 7 showing the heat transfer direction with arrows A from the internal structure (for example, the body 24) of the SFP module 14 to the fiber optic connectors. Figure 9 shows a similar view to Figure 8 in cross-section showing some of the SFP module structures for transferring the heat to the connectors.

Figure 10 shows in an enlarged view similar to Figure 7 with two fiber optic connectors partially inserted into the SFP module prior to mating with the TOSA and ROSA devices 60, 70, respectively. Ferrules 230 for carrying the fiber more

communication with the TOSA and ROSA devices 60, 70 are visible.

Figure 11 is a view similar to Figure 10 wherein the two fiber optic connectors 40 are fully mated to the TOSA and ROSA devices 60, 70, respectively.

The TOSA and ROSA devices 60, 70 shown in the figures use metal housings to contain the active elements and dissipate heat into the SFP body 24. The metal housings may be held in place by a collar 26 (like a yoke) to ensure grounding as well as heat transfer into the SFP body 24. If the collar 26 is made of metal, then the collar would also be conductive to heat from the TOSA and ROSA devices 60, 70 to the SFP body. The connection to the PCB does not provide good thermal transfer to the PCB. The directional arrows shown in the Figure 8 shows the direction of heat transfer from the internal components to the SFP body 24. A cover 28 may be placed over the TOSA and ROSA devices to form a pluggable module mountable to a cage structure of the optical device.

LC adapters 42, like a traditional LC adapter, are formed by the SFP body 24 in the example shown. The adapters allow for LC connectors to mate with and latch securely for signal communication with the TOSA and ROSA devices. MPO connectors and adapters can be used, instead, as well as other connector formats. Another connector style, an LX.5 style by CommScope, Inc., is shown in U.S. Patent No. 7510334 (the‘334 patent), the disclosure of which is hereby incorporated by reference. The‘334 patent discloses a metal body suitable for heat transfer in the present system 10. Heat dissipation features are also disclosed in the‘334 patent.

Surface contact on three sides 44, 46, 48 of each LC plug 40 and over the exterior of the TOSA and ROSA sleeves 66, 76 allow for heat to be transferred to each LC plug 40. Preferably the heat from each SFP module is between 0.5W and 2.0W that is dissipated by the LC plugs 40.

The optical connector 40 includes a thermally conductive material, such as aluminum or copper, making up the connector body 50 to move heat away from the SFP body and the TOSA and ROSA sleeves internal to the device housing 12. Heat is transferred to the connector body 50 from external of the connector body 50 by the SFP body 24 to be transferred external from the housing 12 to the connector body 50. See Figures 8 and 12. Heat is also transferred to the connector body 50 from an internal of the connector body 50 by the sleeves 66, 76 of the TOSA and ROSA bodies 60, 70 to be transferred external of the housing 12 to the connector body 50. See Figure 12. From there, the heat can be dissipated by the extending connector body external to the housing 12. The connector may also include other thermal dissipation elements including fins, or other structures. The heat dissipation elements can be incorporated into the fiber cable itself, the connector strain relief boot, and/or the connector body extending outside of the optical transceiver. Cooling air can be provided adjacent the external connector structures. Fans directed at the external connector structures can also be used.

As shown in Figures 13-15, a heat conductive sleeve 90 is provided internal to the LC plug to improve heat transfer from the TOSA and ROSA sleeves 66, 76. The sleeve 90 makes better contact with the TOSA and ROSA sleeves 66, 76, as well as with the LC connector body 50. The sleeve preferably has a snug fit inside the LC plug. One example is a conductive silicon. In Figure 12, an air gap 88 (exaggerated in size) is shown that can hamper heat transfer from the TOSA and ROSA sleeves 66, 76 to the connector body 50. In some cases, pocket 92 of connector body 50 may need to be enlarged in diameter from a regular connector diameter as shown in Figure 12, to accommodate a sufficiently robust sleeve 90.

Sleeve 90 improves the physical contact between the TOSA and ROSA sleeves 66, 76, and the LC connector body 50. In the case of metallic bodies, such surfaces may be roughed somewhat and have a reduced about of physical contact. Also, tolerances of the parts require a non-binding connection of metal on metal, otherwise the parts would not slide together.

Sleeve 90 needs to be of a material that can take up tolerance issues and still provide good physical contact. Moldability is also likely to be beneficial. Moldable conductive plastic and rubber are possible choices for dissipating the heat from the SFP module. Other characteristics of the material include compressibility. Thixotropic materials may work as well to allow for the number of typical lifetime insertions of the connectors, such as 350 times. The material can also be machined. In general, a more effective sleeve 90 is one that has good heat transfer between the TOSA and ROSA sleeves 66, 76, and the LC connector body 50 over what is provided by the commercial TOSA and ROSA sleeves 66, 76, and the LC connector body 50 made from a heat conductive that has the other properties of the connector, such as strength and durability to function as a fiber optic connector.

An example of a fiber optic connector or plug 220 useable with the SFP module is discussed herein with respect to Figures 16-18 to provide further context to the inventive nature of the connector and heat dissipation properties of the present application.

Referring now to Figures 16-18, the outer housing of a fiber optic connector normally includes features to ensure fixed coupling to a matching format adapter of the SFP module. For example, as shown for a conventional LC style or format fiber optic connector 220 in Figures 16-18, a housing 222 of the connector 220 may define a front housing portion 224 and a rear housing portion 226. The LC connector 220 includes a ferrule assembly 228 defined by a ferrule 230, a hub 232, and a spring 234. A rear end 236 of the ferrule 230 is secured within the ferrule hub 232. When the LC connector 220 is assembled, the ferrule hub 232 and the spring 234 are captured between the front housing portion 224 and the rear housing portion 226 of the connector housing 222 and a front end 238 of the ferrule 230 projects forward outwardly beyond a front end 240 of the connector housing 222. The spring 234 is configured to bias the ferrule 230 in a forward direction relative to the connector housing 222.

In certain embodiments of the connector 220, the front housing portion 224 may be formed from a molded plastic with heat conductive properties. Alternatively front housing portion 224 can be made of metal. The front housing portion 224 defines a latch 242 extending from a top wall 244 of the front housing portion 224 toward the rear end 246, the latch 242 extending at an acute angle with respect to the top wall 244 of the front housing portion 224. The front housing portion 224 in the depicted embodiment also includes a latch trigger 248 that extends from the rear end 246 of the front housing portion 224 toward the front end 240. The latch trigger 248 also extends at an acute angle with respect to the top wall 244. The latch trigger 248 is configured to come into contact with the latch 242 for flexibly moving the latch 242 downwardly.

When the fiber optic connector 220 is placed in an LC format adapter for optically coupling light to another source (TOSA or ROSA devices), the latch 242 functions to lock the fiber optic connector 220 in place within the adapter. The fiber optic connector 220 may be removed from the adapter by depressing the latch trigger 248, which causes the latch 242 to be pressed in a downward direction, freeing catch portions 252 of the latch 242 from the fiber optic adapter. A strain relief boot 256 may be slid over a rear end 258 of the rear housing portion 226 and snap over a boot flange 260 to retain the boot 256 with respect to the connector housing 222. The rear end 258 of the rear housing portion 226 defines a crimp region 262 for crimping a fiber optic cable’s strength layer to the rear housing portion 226, normally with the use of a crimp sleeve. An exterior surface 264 of the rear housing portion 226 defining the crimp region 262 can be textured (e.g., knurled, ridged, provided with small projections, etc.) to assist in retaining the crimp on the housing 222.

Movement of the ferrule 230 of the LC connector in a rear direction relative to the connector housing 222 under the bias of the spring 234 causes the optical fiber to be forced/displaced in a rear direction relative to the connector housing 222 and the jacket of the fiber optic cable. The biased movement of the ferrule 230 allows for any geometry discrepancies and tolerance variations when axially mating to another device.

Claims

What is claimed is:

1. A fiber optic transceiver system comprising:

a housing including an internal circuitry for converting optical signals to electrical signals and for converting electrical signals to optical signals;

a cage mounted within the housing;

a pluggable transceiver module mounted in the cage;

a fiber optic connector connected to the module, wherein heat is transferred from the module to the connector.

2. The fiber optic transceiver system of claim 1, wherein the fiber optic connector includes a heat conductive body, and a ferrule containing an optical fiber.

3. The fiber optic transceiver system of claim 1, wherein the fiber optic connector includes a heat conductive sleeve inserted into an internal front chamber of the fiber optic connector sized to surround a TOSA or ROSA sleeve.

4. The fiber optic transceiver system of claim 1, wherein the pluggable transceiver module includes a TOSA device and a ROSA device, each TOSA and ROSA device including a metallic sleeve which receives a ferrule of a fiber optic connector.

5. The fiber optic transceiver system of claim 1, wherein the pluggable transceiver module includes any device capable of transmitting and receiving fiber optic signals.

6. The fiber optic transceiver system of claim 1, wherein the cage does not include any heat sinks.

7. The fiber optic transceiver system of claim 1, wherein the heat dissipation is by heat transfer from the fiber optic connector or connectors exterior of the housing into the air external of the housing.

8. The fiber optic transceiver system of claim 1, further comprising a fan for moving air past the fiber optic connector or connectors on the exterior of the housing.

9. The fiber optic transceiver system of claim 1, further comprising providing cooling air adjacent to the fiber optic connectors.

10. The fiber optic transceiver system of claim 1, wherein the heat generated from each pluggable transceiver module is between 0.5 watts and 2.0 watts.

11. The fiber optic transceiver system of claims 2-10, wherein the fiber optic connector includes a heat conductive sleeve inserted into an internal front chamber of the fiber optic connector sized to surround a TOSA or ROSA sleeve.

12. The fiber optic transceiver system of claims 2-10, wherein the pluggable transceiver module includes a TOSA device and a ROSA device, each TOSA and ROSA device including a metallic sleeve which receives a ferrule of a fiber optic connector.

13. The fiber optic transceiver system of claims 2-10, wherein the pluggable transceiver module includes any device capable of transmitting and receiving fiber optic signals.

14. The fiber optic transceiver system of claims 2-10, wherein the cage does not include any heat sinks.

15. The fiber optic transceiver system of claims 2-10, wherein the heat dissipation is by heat transfer from the fiber optic connector or connectors exterior of the housing into the air external of the housing.

16. The fiber optic transceiver system of claims 2-10, further comprising a fan for moving air past the fiber optic connector or connectors on the exterior of the housing.

17. The fiber optic transceiver system of claims 2-10, further comprising providing cooling air adjacent to the fiber optic connectors.

18. The fiber optic transceiver system of claims 2-10, wherein the heat generated from each pluggable transceiver module is between 0.5 watts and 2.0 watts.