Silicon packaging for opto-electronic modules

An opto-electronic apparatus comprising a base layer, one or more photonic elements positioned on the base layer, and an optical layer suspended over the base layer, the optical layer including a moveable optical element positioned over at least one of the photonic elements. A process comprising forming a base layer, placing one or more photonic elements on the base layer, and suspending an optical layer over the photonic elements on the base layer, the optical layer including a moveable optical element.

TECHNICAL FIELD

The present invention relates generally to opto-electronic devices and in particular, but not exclusively, to microelectromechanical (MEMS) packaging for opto-electronic modules.

BACKGROUND

The rapid scale-up of opto-electronic components, as well as the difficulties of manufacturing of opto-electronic components in high volumes, have been recognized as a key challenge in meeting the anticipated demand for high-bandwidth telecommunication equipment. Currently, active opto-electronic modules such as 10 Gb/s laser transmitters and receivers are produced in so-called “butterfly packages.” Butterfly packages allow the incorporation of many features, but they are bulky and are also expensive to manufacture because their assembly is difficult to automate and many assembly functions must be performed by hand.

To reduce the cost and ease the automated assembly, the industry is today adopting a new packaging standard known as a TO (Transistor Outline) can package leveraged from existing technology from lower data rate (1-2 Gbs) equipment. While it offers some improvements over the butterfly package, when applied to high-bandwidth equipment this new TO can packaging is suffering from several performance and functional limitations like high optical coupling efficiency and low thermal cooling capability.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Embodiments of an apparatus, process and system including microelectromechanical (MEMS) packaging of opto-electronic modules are described herein. In the following description, numerous specific details are described to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail but are nonetheless encompassed within the scope of the invention.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in the following description do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

FIG. 1illustrates an embodiment of an optical assembly100. The optical assembly100includes an embodiment of a multi-layer opto-electronic package104that includes optical microelectromechanical (MEMS) components. To allow the opto-electronic package104to communicate with other optical components, the optical assembly100includes a receptacle102that can be attached to the opto-electronic package104. The receptacle102provides a way to attach an optical fiber (not shown) to photonic components within the package104using an optical fiber connector that can be attached to the receptacle102, thus putting the photonic components in optical communication with other devices. The opto-electronic package104can be either a transmitter or a receiver, and can therefore transmit signals to or receive signals from other optical components.

FIG. 2illustrates an embodiment of the components of the opto-electronic package104. The opto-electronic package104comprises a multi-layer stack including a base layer202, a spacing layer204and an optical MEMS layer206comprising a MEMS microstage. The base layer202supports the entire package104and provides paths through which electrical signals and power can be delivered to photonic and other elements within the package. In addition, the base layer202provides a heat transfer path for heat generated within the package104to escape.

In the embodiment shown, the base layer202includes various photonic and electronic elements positioned or formed thereon. The base layer202supports the various photonic and electronic elements that are placed thereon and provides electrical connections to the photonic and electronic elements.

The spacing layer204is attached on top of the base layer202. The spacing layer surrounds the photonic elements and provides hermeticity of the package. The spacing layer204also includes provisions such as electrical traces to provide signals and/or power to the optical MEMS layer206. In addition, the spacing layer suspends the optical MEMS layer206above the photonic elements in the base layer and sets a specific and known distance between the photonic components on the base layer and the vertex of a moveable optical element, such as a lens found in the optical MEMS layer206, and also can ensure an electrical connection between the inside and the outside of the package through the hermetic seal of the package.

The final element in the opto-electronic package104is an optical MEMS layer206formed over the spacing layer204and the base layer202. In some embodiments the optical MEMS layer206can be placed within the hermetically sealed portion of the package104, but in other embodiments the optical MEMS layer can be placed outside the hermetically sealed portion. Details of embodiments of the base layer202, spacing layer204and optical MEMS layer206are discussed below in connection withFIGS. 3-7.

FIGS. 3 and 4illustrate the details of an embodiment of the base layer202. The base layer202is generally rectangular and is formed on a substrate302. In one embodiment the substrate302is made of silicon, although in other embodiments other materials or other combinations of materials can be used.

Various photonic and electronic components are placed on the substrate302. In the embodiment shown, a edge emitting laser diode306is attached on the substrate302and various other active or passive optical elements, such as lens308and turning mirror310, are attached on the substrate to condition and direct a laser beam emanating from the laser diode304. One or more wire-bonding pads (not shown) provide attachment points for wires to provide electrical power, electrical signals, or both, as the case may be, to the electronic and photonic components on the base layer. The illustrated embodiment is only one possible combination of photonic elements that can be used; in other embodiments, more, less or different photonic elements. For example, in a different embodiment the edge-emitting laser can be replaced with a light emitting diode (LED). In other embodiments, the edge-emitting laser can be replaced with a vertical surface emitting laser (e.g., a VCSEL), in which case elements such as the turning mirror310can be omitted.

A seal ring304is formed at or near the perimeter of the substrate302. The seal ring304surrounds the area306and most of the electrical traces308. The purpose of the seal ring304is to allow for control of the spacing between the base layer202and the spacing layer204, as well as to allow the base layer to form a hermetic seal with the spacing layer204when that layer is later placed on the base layer (seeFIG. 7). In one embodiment, the seal ring304may be formed of gold, although in other embodiments the seal ring304can be formed of multiple different metal layer like Titanium (Ti), Nickel (Ni), Gold (Au), Platinum (Pt), or combinations or alloys of these metals. In further embodiments, different variations of silicon materials, materials other than silicon, or combinations of silicon and non-silicon materials can be used.

FIG. 4further illustrates the construction of the embodiment of the base layer202. In the embodiment shown, the laser diode306emits a laser beam in the direction of the optical element308, which in this embodiment is a lens but in other embodiments can be a different optical element. The lens308collimates the beam exiting the laser and directs the collimated beam toward the turning mirror310, which turns the collimated laser beam through about 90°, thus turning the laser beam out of the plane of the base layer202. In other embodiments it is of course possible to use the turning mirror to turn the beam through an angle other than about 90°. When the optical layer208(described below in connection withFIGS. 5 and 6) is in place, the collimated beam is focused by the moveable optical element402such that it is launched into the end of an optical fiber404. Since the moveable optical element402is moveable, it can me moved around to optimize the optical coupling between the laser diode306and the optical fiber404when the optical fiber is connected to the package104through the receptacle102, as shown inFIG. 1. As described above, in other embodiments more, less or different photonic elements can be used. For example, in a different embodiment the edge-emitting laser can be replaced with a light emitting diode (LED) or the edge-emitting laser can be replaced with a vertical surface emitting laser (e.g., a VCSEL), in which case elements such as the turning mirror310can be omitted.

The operation of the base layer202described above is characteristic of a transmitter, but a receiver embodiment of the base layer can also be constructed. In a receiver embodiment, the laser diode306is replaced with a photodetector and the direction of the signal is reversed, such that a signal traveling through the fiber404is emitted from the fiber end and collimated by the moveable optical element402. The collimated signal is then turned about 90°, directed toward turning mirror310, and directed toward the optical element308, which then focuses the incoming signal onto the photodetector. As with the transmitter embodiment described above, other embodiments of the receiver can include more, less or different components.

FIGS. 5 and 6illustrate the details of an embodiment of the optical MEMS layer206comprising an MEMS microstage.FIG. 5illustrates a top view of an embodiment of the MEMS microstage arrangement adapted to provide2degrees of mobility, referred to herein as the X/−X and Y/−Y directions. In the illustrated embodiment both degrees of mobility are translations, but in other embodiments the degrees of mobility may include translations, rotations, or both. As illustrated optical MEMS layer206includes various elements formed on a substrate510. Substrate510may be formed of a wide range of substrate materials, including but are not limited to, silicon, silicon-on-insulator, and so forth. Stage516may be formed of a wide range of materials, including but are not limited to ceramic materials or semiconductor materials like silicon.

The elements formed on substrate510include moveable optical element402and a drive arrangement including micro drives502a-502d, coupled to each other as shown. As described in more detail below, micro drives502a-502dare adapted to selectively cooperate with one another to provide moveable optical element402with two degrees of mobility: a first degree of mobility along the X/−X direction, and a second degree of mobility along the Y/−Y direction. In particular, pairs of the micro drives502a-502d—for example, micro drives502b-502c, micro drives502a-502d, micro drives502a-502cor micro drives502a-502d—may be complementarily activated to provide the two degrees of mobility, e.g., X with Y/−Y, −X with Y/−Y, Y with X/−X, or −Y with X/−X.

Optical MEMS layer206further includes stage516, on which moveable optical element402is disposed. Moveable optical element402may be integrally formed on stage516, or attached to stage516. Optical element402may be any micro object where at least 1 degrees of mobility are desired (translation or rotation). Examples of optical element402include, but are not limited to, lenses, mirrors, diffractive elements, and so forth. For the embodiment, optical MEMS layer206is designed to have optical element402positioned substantially at the center of substrate510, when it is not moved for any amount of distance in either the X/−X or Y/−Y directions. For ease of understanding, this position will be referred to as the “initial” position. In alternate embodiments, the “initial” position may be off-centered.

Optical MEMS layer206also includes compliant suspension beams512a-512b, to which stage516(and therefore, moveable optical element402) is attached. For the embodiment, compliant suspension beams512a-512bare substantially elongated as well as curved in shape. Further, micro drives502cand502dare coupled to one end of compliant suspension beams512a-512b, while micro drives502cand502dare coupled to the other end of compliant suspension beams512a-512b. As described earlier, optical element402is attached to compliant suspension beam512a-512b, which may comprise one or more layers of e.g. one or more metals or their alloys with compliant properties. Such metals include, but are not limited to, copper (CU), titanium (Ti), nickel (Ni), Gold (Au), silver (Ag), tantalum (Ta), molybdenum (Mo), chromium (Cr), cobalt (Co), Silicon (Si) and so forth. Resultantly, compliant suspension beams512a-512bmay be compressed to provide optical element402with mobility for a distance along the +Y direction, or extended (stretched) to provide optical element402with mobility for a distance along the −Y direction.

Micro drives502band502care adapted to be activated complementarily to move compliant suspension beams512a-512b, and therefore moveable optical element402, a distance along the X direction in a coordinated manner. Similarly, micro drives502aand502dare adapted to be activated complementarily to move compliant suspension beams512a-512b, and therefore moveable optical element402, a distance along the −X direction. Similarly, micro drives502aand502care adapted to be activated complementarily to compress compliant suspension beams512a-512b, to move moveable optical element402a distance along the Y direction, whilst micro drives502band502dare adapted to be activated complementarily to extend compliant suspension beams512a-512b, to move moveable optical element402a distance along the −Y direction.

In one embodiment, each of micro drives502a-502dis a comb drive including at least two portions, at least one of which is adapted to be linearly moveable towards the other. In various embodiments, the other portion is fixed to substrate510through corresponding springs513a-513d. Further, in various embodiments, the moveable portion is linearly moved towards the fixed portion electrostatically, that is when the drive is electrically energized. The amount of movement is a function of the intensity a micro drive is electrically energized. Accordingly, it is possible to achieve movements in two directions, by complementarily activating two cooperating micro drives with different intensities. In various embodiments, each of micro drives502a-502dmaybe independently activated with the same or different intensities. Note that a desired difference in intensities may be effectuated by activating a pair of micro drives with different intensities having the difference, including activating one of the two micro drive with an intensity equals to the difference, and “activating” the other micro drive with zero intensity. Accordingly, the term “complementary activation” as used herein, including the claims, include the “zero” form of “activation,” with one of the micro drives “activate” with a zero intensity.

In various embodiments, optical MEMS layer206may further include a number of springs513a-513dto which micro drives502a-502dare coupled. Springs513a-513dmay be attached to substrate510. For the embodiment, springs513a-513dare also substantially elongated in shape, disposed substantially in parallel with micro drives502a-502d. Springs513a-513dmay be formed with one or more layers of metals or alloys with compliant properties, including but not limited to the metals earlier enumerated for the compliant beams.

FIG. 6further illustrates a cross-sectional view of the embodiment of the optical MEMS layer206. As shown in this figure, optical MEMS layer206may be further provided with electrodes522under stage516. Electrodes522are adapted to electrostatically attract stage516, thereby providing a holding or locking function for holding or locking stage516, and therefore optical element402in place, after stage516and optical element402have been moved to a desired operational location. In particular, the holding and locking operation may be performed post assembly or after substantial completion of assembly of the opto-electronic package104. In other embodiments, in addition to or instead of electrodes522, one or more regions of substrate may be energized to attract stage516, thereby holding or locking stage516, and therefore optical element402, in place after they have been moved to a desired operational location/position. In still other embodiments, the holding or lock down function may be effectuated employing other physical principles, including but are not limited to electromagnetic, piezoelectrical bimorph, thermal bimorph, and the like.

The holding or locking in-place feature is particularly useful in conjunction with the moveable optical element402, for holding or locking the optical element in place after it has been moved into a desired operational location, e.g., a location where it is in alignment with a light source and an optical fiber. As described earlier, this operation may be performed post assembly or after substantial completion of opto-electronic assembly104. Further, at a later point in time after operated for a while, the holding or locking may be undone, to render the moveable optical element402to be moveable again to facilitate re-alignment of the elements. The moveable optical element402may be re-locked again after the re-alignment. The unlocking and realignment may be desired because of a change in operational requirement or because the elements became misaligned during operation. The unlocking, re-alignment, and re-locking process may be repeated any number of times as needed.

FIG. 7illustrates the embodiment of the opto-electronic package104in its assembled form. The photonic elements, including the laser306, the optical element308and the turning mirror310, are positioned on the base layer202. The spacing layer204surrounds the photonic elements is positioned on the base layer202in contact with the seal ring304, such that a hermetic seal is created. The optical MEMS layer206is positioned on the spacing layer204such that it is suspended above the photonic elements. The hermetic seal formed between the spacing layer204and the seal ring304results all the photonic elements being hermetically sealed within the package104.

FIG. 8illustrates an alternative embodiment of an opto-electronic assembly800. The optical assembly800includes an embodiment of a multi-layer opto-electronic package804that includes microelectromechanical (MEMS) components and also includes a thermoelectric cooler (TEC) that can be used to control the temperature of photonic elements within the package804. To allow the opto-electronic package804to communicate with other optical components, the optical assembly800includes a receptacle802that can be attached to the opto-electronic package804. The receptacle802provides a way to attach an optical fiber (not shown) to photonic components within the package804using an optical fiber connector (also not shown) that can be attached to the receptacle802, thus putting the photonic components in optical communication with other devices. The opto-electronic package804can be either a transmitter or a receiver, and can therefore transmit signals to or receive signals from other optical components.

FIG. 9illustrates an embodiment of the components of the opto-electronic package804. The opto-electronic package804comprises a multi-layer stack including a base layer902, a photonic layer904, a spacing layer904, and an optical layer906. The base layer902supports the entire package804and provides paths through which electrical signals and power can be delivered to photonic and other elements within the package. In addition, the base layer902provides a heat transfer path for heat generated within the package to escape.

In the embodiment shown, the photonic layer904is formed on the base layer902and includes various photonic elements thereon. The photonic layer904supports the various photonic and electronic elements that are placed thereon, provides electrical connections in addition to or instead of those found on the base layer, and can be used in conjunction with the base layer to form a thermoelectric cooler (TEC) so that the temperature of the photonic and electronic elements can be controlled.

The spacing layer906is formed on the base layer902. The spacing layer surrounds the base layer and provides thermal isolation between the base layer and the rest of the package. In addition, the spacing layer sets a specific and known distance between the photonic components on the photonic layer904and the vertex of an optical element such as a lens found in the optical MEMS layer908, and also ensures an electrical connection between the inside and the outside of the package through the hermetic seal of the package.

The final element in this embodiment of the package804is an optical MEMS layer908positioned over the spacing layer906and the photonic layer904. In some embodiments the optical MEMS layer908can be placed within the hermetically sealed portion of the package804, but in other embodiments the optical MEMS layer can be placed outside the hermetically sealed portion. The optical MEMS layer908is similar in construction to the optical MEMS layer206described above in connection withFIG. 2, so details of the construction of optical MEMS layer908are therefore not discussed further. Details of embodiments of the base layer902, photonic layer904and spacing layer906are discussed below in connection withFIGS. 10-16.

FIGS. 10 and 11illustrate the details of an embodiment of the base layer902. The base layer902is generally rectangular in shape and is formed on a substrate1002. In one embodiment the substrate1002is made of silicon, although in other embodiments other materials or other combinations of materials can be used. An area1006on the substrate1002is designated to receive the photonic layer904when the photonic layer is placed on the base layer. Prior to placement of the photonic layer in the area1006, a thin film thermoelectric material1010is deposited or pre-formed on the surface of the substrate1002within the area1006. In one embodiment, the thin film thermoelectric material is applied by sputtering, although in other embodiments different processes such as chemical or physical vapor deposition can be used. When the photonic layer904is later placed on the area1006, the thin film thermoelectric material1010is sandwiched between the base layer902and the photonic layer904, forming a micro thermoelectric (TEC) cooler. The TEC formed between the base layer902and the photonic layer904enhances heat transfer to the base layer and is useful in some embodiments to control the temperature of the photonic layer and the components on the photonic layer. For example, if the photonic layer904includes a laser whose output wavelength is sensitive to temperature, the TEC allows excellent control of the laser's temperature and can be used to ensure that the output of the laser is maintained at the desired wavelength. In other embodiments of the opto-electronic package804where the ability to control temperature is not needed, the TEC can be omitted by omitting the thin-film thermoelectric material1010. In still other embodiments where cooling is not needed the photonic layer can be omitted and the photonic components can be placed directly on the base layer, thus essentially merging the photonic layer into the base layer.

One or more electrical traces1008are formed on the surface of the substrate1002, leading from near the area1006to near the perimeter of the substrate1002. In one embodiment, the electrical traces can be formed of metal using standard metallization techniques, although different techniques are of course possible, for example where the electrical traces are made using conductive non-metals. The electrical traces1008may reside on the surface of the substrate1002, or may extend into the interior of the substrate, for example in metal-filled vias. Electrical traces1008can later be used to provide power to the TEC formed in area1006(if present), as well as power, electrical signals, and so forth to optical or electronic components on the photonic layer904.

A seal ring1004is formed at or near the perimeter of the substrate1002. The seal ring1004surrounds the area1006and most of the electrical traces1008. The purpose of the seal ring1004is to allow for control of the spacing between the base layer902and the spacing layer906, as well as to allow the base layer to form a hermetic seal with the spacing layer906when the spacing layer is later placed on the base layer. In one embodiment, the seal ring1004may be formed of silicon, although in other embodiments the seal ring1004may be formed of different variations of silicon materials, materials other than silicon, or combinations of silicon and non-silicon materials.

FIGS. 12 and 13together illustrate the details of an embodiment of the photonic layer904. The photonic layer904includes a substrate1202, which in the embodiment shown is made of silicon but in other embodiments can be made of other materials. Various photonic and electronic elements can be formed or placed on the photonic layer904. In the embodiment shown, a edge emitting laser diode1204is formed on the substrate1202and various other active or passive optical elements, such as turning mirror1208, are formed on the substrate to condition and direct a laser beam emanating from the laser diode1204. One or more wire-bonding pads1212are formed on the base layer to provide attachment points for wires to provide electrical power, electrical signals, or both, as the case may be, to the electronic and photonic components on the base layer. Electrical traces (not shown) lead from the wire bonding pads to the relevant components. Additional electronic or photonic components1214and1216, such as resistors, capacitors, inductors, voltage regulators, etc, can also be formed on the photonic layer904and connected to the proper components thereon.

FIG. 13illustrates the construction and operation of the embodiment of the photonic layer904. In the embodiment shown, the laser diode1204emits a laser beam in the direction of the turning mirror1208, which turns the laser beam through about 90°, thus turning the laser beam out of the plane of the photonic layer904. In other embodiments it is of course possible to use the turning mirror to turn the beam through an angle other than about 90°. When the optical MEMS layer908(described above in connection withFIGS. 5 and 6) is in place, the laser beam reflected from the turning mirror1208is focused by the moveable optical element402such that it is launched into the end of an optical fiber1304. Since the moveable optical element402in the optical MEMS layer908is moveable, it can me moved around to optimize the optical coupling between the laser diode1204and the optical fiber1304when the optical fiber is connected to the package804through the receptacle802, as shown inFIG. 8. Although not shown in the drawing, in other embodiments additional optical elements, such as a lens, can be used to condition (e.g., collimate or focus) the laser beam as it exits the laser and/or after it is reflected from the turning mirror1208. The illustrated embodiment is only one possible combination of photonic elements that can be used; in other embodiments, more, less or different photonic elements. For example, in a different embodiment the laser diode can be replaced with an edge-emitting laser or a light emitting diode (LED). In other embodiments, the edge-emitting laser can be replaced with a vertical surface emitting laser (e.g., a VCSEL), in which case elements such as the turning mirror310can be omitted.

The operation of the photonic layer904described above is characteristic of a transmitter, but a receiver embodiment of the base layer can also be constructed. In a receiver embodiment, the laser diode1204is replaced with a photodetector and the direction of the signal is reversed, such that a signal traveling through the fiber1304is emitted from the fiber end and collimated by the moveable optical element402. The collimated signal is then turned 90°, directed toward turning mirror1208, and directed toward the photodector. As with the transmitter embodiment, since the optical element402is moveable, it can be moved around to optimize the optical coupling between the optical fiber1304and the photodetector1204and when the optical fiber is connected to the package804through the receptacle802, as shown inFIG. 8. Although not shown in the drawing, in other embodiments additional optical elements, such as a lens, can be used to condition (e.g., collimate or focus) the laser beam before and/or after it is reflected from the turning mirror1208.

FIGS. 14 and 15illustrate the details of an embodiment of the spacing layer906.FIG. 14shows that the spacing layer906includes a substrate1402, which in the embodiment shown is made of silicon but in other embodiments can be made of other materials. In one embodiment, the thickness of the substrate1402is of the same order of magnitude as the thickness of the substrate1202of the photonic layer904, but in other embodiments the thickness of substrate1402can be greater that, less than, or the same as the overall thickness of the photonic layer904.

An opening1404in the substrate is designed to accommodate and surround the base layer, meaning that the length and width of the opening1404are selected to be greater than or equal to the length and width of the photonic layer904. A seal ring1406is formed to surround the opening1404. In one embodiment, the seal ring1406may be formed of silicon, although in other embodiments the seal ring1406may be formed of different variations of silicon materials, materials other than silicon, or combinations of various materials. The seal ring1406allows the optical MEMS layer908to form a hermetic seal with the spacing layer906when that layer is later formed on the base layer. With the seal ring1004forming a hermetic seal between the base layer902and the spacing layer906, and the seal ring1406forming a hermetic seal between the spacing layer906and the optical MEMS layer908, the base layer becomes hermetically sealed from the exterior, thus protecting the photonic elements on the photonic layer904from contamination, moisture, and so on.

FIG. 15illustrates the construction of the spacing layer906, in particular the positioning and routing of a plurality of electrical traces1408. The electrical traces1408extend from an edge of the opening1404to the edge of the substrate1408. To ensure that the seal ring1406can form a hermetic seal with the optical layer, the electrical traces1408extend approximately from the edge of the opening1404to the inner edge of the seal ring1406. Before the traces1408reach the seal ring, they are routed through the substrate into a pair of notches1410in the bottom of the substrate1402. The shape of the notches1410results in a substantially V-shaped (or cylindrical) protrusion1412. The traces are formed along the surfaces of the protrusion1412, and re-emerge to the top of the substrate1402on the outer side of the seal ring1406. The electrical traces1408then extend continuously from outside the seal ring1406approximately to the edges of the substrate1402, while ensuring that the seal ring1406can maintain a hermetic seal. The electrical traces can be formed using standard metallization processes. The electrical traces are used to provide electrical power or signals to the elements on the base layer, as well as to provide electrical power to the optical MEMS layer908which will be formed on the spacing layer908. In one embodiment, wire bonding can be used to connect each trace to corresponding wire bonding pads1212on the base layer.

FIG. 16illustrates the embodiment of the opto-electronic package804in its assembled form. The photonic layer904is positioned on the base layer902, with the layer of thermoelectric material1010sandwiched between the photonic and base layers. The spacing layer906surrounds the photonic layer904and is positioned on the base layer in contact with the seal ring1004, such that a hermetic seal is created. The optical MEMS layer908is then positioned on the spacing layer, such that the moveable optical element402is above the photonic elements. The optical MEMS layer908rests on the seal ring1406that surrounds the opening in the spacing layer, and creates a hermetic seal. The hermetic seal formed between the spacing layer and the seal ring1004and the hermetic seal formed between the optical MEMS layer908and the seal ring1406result in the photonic layer, and hence all the photonic elements thereon, being hermetically sealed within the package804.

FIG. 17schematically illustrates an embodiment of a system1700incorporating the present invention. The system1700is a transponder that can both transmit and receive optical signals via optical fiber. The transmission portion of the transponder1700includes a laser1702coupled to some other optical component by an optical fiber1706. The laser is coupled to a driver1710, and both the laser1702and the driver1710are coupled to a controller1714. A multiplexer1716is coupled to the driver, and one or more signal sources (not shown) are coupled to the multiplexer1716. The receiving portion of the transponder1700includes a receiver1704coupled to an optical signal source by an optical fiber1708. The receiver1704is coupled to a LIM unit1712, and the LIM unit is in turn coupled to a de-multiplexer1718. In the transponder1700, the laser1702, the receiver1704, or both, can be opto-electronic packages such as packages104and804described above. Other embodiments of the system can include more, less or different components. In another embodiment, for example, one or both of the mutliplexer and de-multiplexer can be omitted, depending on the transponder interface standard.

In operation, the multiplexer1716receives one or more electrical signals from one or more signal sources (not shown). The multiplexer multiplexes the multiple signals it receives and sends a multiplexed signal to the driver1710. Under the control of the controller1714, the driver1710and the laser1702modulate the multiplexed signal onto an optical carrier, and the multiplexed optical signal is then launched into the optical fiber1706. On the receive side, the receiver1704receives an optical signal from the fiber1708. The receiver1704and LIM unit1712perform an opto-electronic conversion and convert the optical signal into an electrical signal. The electrical signal is then fed into the de-multiplexer for separation into de-multiplexed components signals. Each component signal is then transmitted to its destination.

The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. These modifications can be made to the invention in light of the above detailed description.