Patent Application
20050207458
The present invention relates generally to the field of optoelectronics.
Laser light has been employed to facilitate communication.
Typically, for intermediate or long range communication, the laser light source has to be cooled to ensure proper functioning of the optoelectronics, that is, the optical and electronic components within the optoelectronic modules. Currently, what is known as the “butterfly can” is probably the most popular form factor employed for this kind of laser transmitter modules, i.e. those requiring the laser light sources and/or their companion electronics to be cooled. In general, “butterfly can” has a relatively large footprint, and is relatively expensive to make.
Recently, a number of smaller footprint transceivers, such as XFP or SFP, have emerged. Traditional packaging, such as butterfly can, is unable to meet the smaller footprint and lower cost requirement. [XFP=10-Gigabit Small Form Factor Pluggable, and SFP=Small Form Factor Pluggable].
Transistor-Online (TO) packaging has been developed for 2.5 Gbit/sec or lower speed communication. It fits the smaller transceiver's footprint, and has lower cost. Applying TO packaging to higher speed applications, such as 10 Gbit/sec, would meet the new market needs. However, traditional TO cans have no provision for cooling elements, which are often required for high speed applications of 10 Gbit/sec and beyond for intermediate or long range communication.
In other words, butterfly cans are designed to accommodate cooling elements, but their footprints are too big, and too costly to manufacture, whereas TO packaging has a smaller footprint, and lower cost to manufacture, but it has no provision for cooling elements for high speed and long range applications requiring such cooling.
The present invention will be described by way of exemplary embodiments, but not limitations, illustrated in the accompanying drawings in which like references denote similar elements, and in which:
a-3b illustrate a perspective view and a bottom view of the thermo electric cooler of
Illustrative embodiments of the present invention include, but are not limited to, an optoelectronic module, a communication interface and/or system having such optoelectronic module.
Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments.
The phrase “in one embodiment” is used repeatedly. The phrase generally does not refer to the same embodiment; however, it may. The terms “comprising”, “having” and “including” are synonymous, unless the context dictates otherwise.
Referring now to
Note that the reference to the surface of TEC 110 on which laser light source 102 is disposed as a “top” surface is made merely for ease of description and understanding. The surface could have been referred to e.g. as a “bottom” or a “side” surface. Whether, it should be referenced as a “top”, a “bottom” or a “side” surface is a matter of perspective, depending on how optoelectronic module 100 is viewed. Accordingly, the reference convention is not to be read as restrictive of the invention. Further, this note applies to all subsequent references to other surfaces of other elements as “top”, “bottom” or “side” surfaces. That is, all such references are for ease of description and understanding. The surfaces could have been referenced in other manners depending on how the elements are viewed respectively, and the references are not to be read as restrictive on the invention.
In various embodiments, laser light source 102 may be a vertical cavity surface-emitting laser device, a Fabry-Perot laser device, a distributed feedback laser device, a laser diode device, and other laser devices of the like. Further, laser light source 102 is driven for a high speed communication application, e.g. 10 Gbit/sec or higher, requiring cooling during operation.
In various embodiments, TEC 110 is thermally rated to meet at least the thermal dissipation requirement of laser light source 102. Referring now briefly to
Referring back to
As illustrated, for the embodiment, TEC 110 is disposed in the lower portion of substrate 112, and the “step” or higher portion of substrate 112 has a height that is substantially the same as TEC 110, to allow laser light source 102 to be substantially co-planar with the “top” surface of the step or higher portion of substrate 112. As illustrated, this feature allows e.g. a driver or an amplifier 104 to be optionally placed in very close proximity of laser light source 102. For these embodiments, vias 122b are employed to facilitate routing of electrical connections from selected one(s) of I/O pins 116 to optional driver/amplifier 104. The co-planar and proximal attributes enable relatively short leads to be employed to electrically couple laser light source 102 to optional driver or amplifier 104 (if it is disposed as shown). The arrangement potentially contributes to improving the performance of optoelectronic modules 100.
In various embodiments, substrate 112 is made of a ceramic material with a suitable thermal conductivity. Similarly, ceramic may be used to form the substrate of RF circuity. More specifically, in various embodiments, the ceramic material is a selected one of aluminum nitride, beryllium oxide, alumina, and other ceramic materials with suitable thermal conductivity and similar dielectric constants.
Still referring to
Further, in various embodiments, one or more other electronic elements, represented by element 106, may also be disposed on the “top” surface of TEC 110.
Continuing to
More specifically, overhanged ring 114 is designed to mate with flanges 119 of cap 118. Cap 118 may be mated with overhanged ring 114 in a variety of manners, including but are not limited to welding, in particular, projection welding. In various embodiments, overhanged ring 114 is about 0.5 mm in thickness.
For the embodiment, overhanged ring 114 is substantially square in shape, however, in alternate embodiments, overhanged ring 114 may assume other geometric shapes, including but are not limited to other polygon, circular or oval shapes.
For the embodiment, in addition to flanges 119, cap 118 includes optical window 120. More specifically, optical window 120 is complementarily disposed at the center portion of cap 118 to facilitate exit of the orthogonally re-directed laser light bundles emitted by laser light source 102. In various embodiments, optical window may be a flat glass window, a ball lens, an aspherical lens, a GRIN lens, or other lens of the like.
Still referring to
Except for the incorporation of optoelectronic module 100 with networking interface 402, elements 402-404 represent a broad range of these elements known in the art or to be designed.
In various embodiments, example system 400 may be a router, a switch, a gateway, a server, and so forth.
As those skilled in the art would appreciate, the foregoing embodiments provide an optoelectronic package having a relatively small footprint, and yet able to accommodate cooling elements for a high speed e.g. 10 Gbit/sec application. In various embodiments, the length and width of the module may be about 5.4 mm, and the height of the module may be about 5˜10 mm, providing a substantially smaller foot print than the butterfly can, whose length is over 19 mm, width over 7 mm, and height over 7 mm. A laser in such package may nonetheless dissipate e.g. 0.1 W heat, with a heat of e.g. 0.2˜0.4 W going into the module from the ambient, yet the TEC of this footprint can dissipate the total heat (as much as 0.5 W) to maintain the temperature of the laser device at about 25˜35° C., while the module case in the communication system is about 70° C.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described, without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
