Patent Description:
The microelectronic industry has begun using optical connections as a way to increase bandwidth and performance. Typically, an optical fiber is coupled to a photonics die. The current coupling architectures include direct coupling between the interfaces. Such direct coupling does not fundamentally improve signal-to-noise ratios. In fact, these direct light coupling architectures may result in reflected light at the interface. The reflected light generates optical interference. The optical interference decreases the signal-to-noise ratio and can even result in inaccurate signals being propagated to the receivers. <CIT> discloses a chip package including an optical integrated circuit (such as a hybrid integrated circuit) and an integrated circuit that are adjacent to each in the chip package. The integrated circuit includes electrical circuits, such as memory or a processor, and the optical integrated circuit communicates optical signals with very high bandwidth. <CIT> discloses an optical transmitter module which is smaller and has a higher performance, which can improve the reliability and which can be manufactured at lower costs and allows for stable laser transmission of an optical semiconductor element. The optical transmitter module comprises an optical semiconductor element, an optical fiber optically coupled to the optical semiconductor element, an inline optical isolator provided for the optical fiber, and a package case containing the optical semiconductor element and the optical fiber, includes a substrate member with one end of the optical fiber on the light incident side fixed thereon to be optically coupled to the optical semiconductor element, a thermoelectric cooler with the substrate member joined to the top surface thereof, and a pipe-like support member projecting from the side face of the package case for fixing the optical isolator.

Described herein are photonics packages with a Faraday rotator between an optical cable and the photonics die, in accordance with various embodiments. In the following description, various aspects of the illustrative implementations 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 implementations. 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 implementations.

Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

As noted above, direct optical coupling between an optical cable and the photonics die leads to low signal-to-noise ratios. For example, reflections at the interface may be particularly problematic and leads to poor signal quality. Accordingly, embodiments disclosed herein include the integration of Faraday rotators into the photonics package architectures. An example schematic of the functioning of a Faraday rotator <NUM> is shown in <FIG>.

As shown in <FIG>, the Faraday rotator <NUM> comprises a first polarizer <NUM>, a magnetic region <NUM>, and a second polarizer <NUM> on the opposite side of the magnetic region <NUM> from the first polarizer <NUM>. Incoming light <NUM> may have random polarization. After passing through the first polarizer <NUM>, the light <NUM> may be vertically polarized. In an embodiment, the light <NUM> propagates through the magnetic region <NUM> where the magnetic field results in the polarization being shifted, as shown in light <NUM>. For example, a <NUM>° polarization shift may be provided in some embodiments. Light <NUM> then passes through the second polarizer <NUM>, which restricts light to only the selected polarization shift induced by the magnetic region <NUM>, as shown by light <NUM>. In light passing the opposite direction (i.e., light <NUM>, <NUM>, and <NUM>), the angled polarized light <NUM> and <NUM> passes back through the magnetic region <NUM>. The magnetic region <NUM> again shifts the polarization. For example, when a <NUM>° polarization is used, the polarization of the light <NUM> is further shifted so that light <NUM> is <NUM>° polarized. It is to be appreciated that such a Faraday architecture may result in the filtering out of reflections from the optical path. As such, the signal-to-noise ratio is increased, and performance of the optical interconnects are improved.

Referring now to <FIG>, a cross-sectional illustration of an electronic system <NUM> is shown, in accordance with an embodiment according to the claims. The electronic system <NUM> comprises a patch on interposer (PoINT) architecture. The PoINT architecture may comprise a board <NUM>. The board <NUM> may be a printed circuit board (PCB) or the like. In an embodiment, an interposer <NUM> is attached to the board <NUM> by interconnects <NUM>. The interconnects <NUM> are shown as being solder balls, but it is to be appreciated that any interconnect architecture may be used, such as sockets or the like.

In an embodiment, the interposer <NUM> may comprise conductive routing (not shown). The conductive routing within the interposer <NUM> may allow for conductive coupling between a top surface and a bottom surface of the interposer <NUM>. For example, the conductive routing may comprise pads, traces, vias, and the like.

A patch <NUM> is attached to the interposer <NUM>. For example, the patch <NUM> may be coupled to the interposer <NUM> by interconnects <NUM>, such as solder balls or the like. In an embodiment, the patch <NUM> comprises a core <NUM> and conductive routing layers <NUM> above and below the core <NUM>. Through core vias <NUM> may conductively couple the top routing layer <NUM> to the bottom routing layer <NUM>. However, it is to be appreciated that in some embodiments, a coreless patch <NUM> may also be used.

In an embodiment, the patch <NUM> may comprise a compute die <NUM> and a photonics die <NUM>. The compute die <NUM> may be any type of die, such as, but not limited to a processor, a graphics processor, a field-programmable gate array (FPGA), a system on a chip (SoC), a memory, or the like. In an embodiment, the photonics die <NUM> comprises features for converting signals between the optical regime and the electrical regime. For example, the photonics die <NUM> may comprise a laser and/or a photodiode. In an embodiment, the compute die <NUM> is communicatively coupled to the photonics die <NUM> by a bridge <NUM> that is embedded in the top routing layer <NUM> of the patch <NUM>. The bridge <NUM> provides a dimensionally stable substrate on which high density conductive routing can be provided.

The patch <NUM> is arranged so that it overhangs an edge of the interposer <NUM>. For example, the patch <NUM> in <FIG> overhangs the left edge of the interposer <NUM>. Overhanging the interposer <NUM> allows for a bottom surface of the patch <NUM> to be exposed. Particularly, a space between the underlying board <NUM> and the bottom surface of the patch <NUM> is sufficient to provide an optical connection to the photonics die <NUM> from below. In a particular embodiment, an optical cable <NUM> is connected to a connector <NUM>. The connector <NUM> interfaces with a Faraday rotator <NUM> that passes through a thickness of the patch <NUM>. The Faraday rotator <NUM> is positioned within a footprint of the photonics die <NUM>. As such, an optical path is provided through the Faraday rotator <NUM> from the connector <NUM> to the photonics die <NUM>.

In an embodiment, the Faraday rotator <NUM> comprises a housing <NUM>. The housing <NUM> may be a tube. In an embodiment, the housing <NUM> is mechanically coupled to the patch <NUM> by a dielectric layer <NUM>. As will be described below, the dielectric layer <NUM> is a material that expands during a heat treatment. As such, the Faraday rotator <NUM> can be inserted into the patch <NUM>, and the heat treatment secures the Faraday rotator <NUM> to the patch <NUM>.

In an embodiment, the Faraday rotator <NUM> may comprise a first polarizer <NUM> and a second polarizer <NUM>. The first polarizer <NUM> may be a vertical polarizer and the second polarizer <NUM> may be an angled polarizer (e.g., <NUM>°). That is, the first polarizer <NUM> may be different than the second polarizer <NUM>. In an embodiment, a magnetic region is provided between the first polarizer <NUM> and the second polarizer <NUM>. The magnetic region may comprise a permanent magnet <NUM>. The permanent magnet <NUM> may be a shell that wraps around an optically clear layer <NUM>. The permanent magnet <NUM> has a magnetic field that modifies the orientation of the incoming vertically polarized light. For example, the permanent magnet <NUM> may result in <NUM>° polarized light in some embodiments.

In an embodiment, the efficiency of the Faraday rotator <NUM> may be further improved by including lenses. For example, a first lens <NUM>A may be provided between the first polarizer <NUM> and the connector <NUM>, and a second lens <NUM>B may be provided between the second polarizer <NUM> and the photonics die <NUM>.

Referring now to <FIG>, a series of cross-sectional illustrations depicting a process for fabricating a patch <NUM> is shown, in accordance with an embodiment. The patch <NUM> in <FIG> may be substantially similar to the patch <NUM> in <FIG>.

Referring now to <FIG>, a cross-sectional illustration of a patch <NUM> is shown, in accordance with an embodiment. In an embodiment, the patch <NUM> may comprise a core <NUM> with routing layers <NUM> above and below the core <NUM>. Through core vias <NUM> may electrically couple the top routing layers <NUM> to the bottom routing layers <NUM>. In yet another embodiment, the patch <NUM> may be coreless. In the illustrated embodiment, conductive traces are shown in the routing layers <NUM>. However, it is to be appreciated that conductive vias, traces, and pads may be provided in the routing layers <NUM> in order to provide the necessary conductive routing. In an embodiment, a bridge <NUM> for providing high density routing may also be provided in the top routing layers <NUM>.

In an embodiment, a hole <NUM> is formed through the patch <NUM>. The hole <NUM> may be formed with any drilling process. For example, the hole <NUM> may be mechanically drilled or drilled with a laser. In the case of a laser drilled hole, the sidewalls of the hole <NUM> may be tapered, as is common in laser drilled architectures. The hole <NUM> passes through the top routing layers <NUM>, the core <NUM>, and the bottom routing layers <NUM>. That is, the hole <NUM> extends through an entire thickness of the patch <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after Faraday rotator <NUM> is inserted into the hole <NUM> is shown, in accordance with an embodiment. In an embodiment, the Faraday rotator <NUM> comprise a housing <NUM> that is tubular. An outer surface of the housing <NUM> may be lined with a dielectric material <NUM>. In an initial state, the outer diameter of the dielectric material <NUM> may be smaller than a diameter of the hole <NUM>.

In an embodiment, the Faraday rotator <NUM> may comprise a first polarizer <NUM> and a second polarizer <NUM>. The first polarizer <NUM> may be a vertical polarizer and the second polarizer <NUM> may be an angled polarizer (e.g., <NUM>°). That is, the first polarizer <NUM> may be different than the second polarizer <NUM>. In an embodiment, a magnetic region is provided between the first polarizer <NUM> and the second polarizer <NUM>. The magnetic region may comprise a permanent magnet <NUM>. The permanent magnet <NUM> may be a shell that wraps around an optically clear layer <NUM>. While shown as a physical layer in <FIG>, it is to be appreciated that the permanent magnet <NUM> may have an air core in some embodiments. The permanent magnet <NUM> has a magnetic field that modifies the orientation of the incoming vertically polarized light. For example, the permanent magnet <NUM> may result in <NUM>° polarized light in some embodiments.

In an embodiment, the permanent magnet <NUM> may be in direct contact with the first polarizer <NUM> and the second polarizer <NUM>. For example, a bottom surface of the permanent magnet <NUM> may be in direct contact with a top surface of the first polarizer <NUM>, and a top surface of the permanent magnet <NUM> may be in direct contact with a bottom surface of the second polarizer <NUM>. The permanent magnet <NUM> may have an outer diameter that is substantially equal to diameters of the first polarizer <NUM> and the second polarizer <NUM>.

In an embodiment, the Faraday rotator <NUM> may also comprise a first lens <NUM>A and a second lens <NUM>B. The first lens <NUM>A is within the housing below the first polarizer <NUM>, and the second lens <NUM>B is within the housing above the second polarizer <NUM>. The lenses <NUM>A and <NUM>B allow for improved efficiency by focusing the light passing through the Faraday rotator <NUM>.

In the illustrated embodiment, the first polarizer <NUM>, the second polarizer <NUM>, and the permanent magnet <NUM> are positioned at approximately a midpoint of the housing <NUM>. That is, the first polarizer <NUM>, the second polarizer <NUM>, and the permanent magnet <NUM> are positioned substantially within the core <NUM> of the patch <NUM>. However, it is to be appreciated that the first polarizer <NUM>, the second polarizer <NUM>, and the permanent magnet <NUM> may be positioned at any vertical location within the patch <NUM>. Additionally, while shown as be directly in contact with each other, embodiments may include spacings between one or more of the first polarizer <NUM>, the second polarizer <NUM>, and the permanent magnet <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a thermal treatment is shown, in accordance with an embodiment. In an embodiment, the thermal treatment may be at an elevated temperature (e.g., <NUM> or more) for a designated period of time. The heat treatment induces a physical change in the dielectric material <NUM>. Particularly, an outer diameter of the dielectric material <NUM> is increased by the heat treatment. For example, the outer diameter of the dielectric material <NUM> may expand to completely fill the hole <NUM>. As such, the dielectric material <NUM> mechanically couples the Faraday rotator <NUM> to the patch <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a compute die <NUM> and a photonics die <NUM> are attached is shown, in accordance with an embodiment. In an embodiment, the compute die <NUM> and the photonics die <NUM> may be attached to the patch by interconnects <NUM>. While shown as solder balls, it is to be appreciated that the interconnects <NUM> may be any first level interconnect (FLI). The photonics die <NUM> may be communicatively coupled to the compute die <NUM> by the bridge <NUM> in the top routing layers <NUM>. In an embodiment, the photonics die <NUM> extends over the Faraday rotator <NUM>. That is, the Faraday rotator <NUM> may be within a footprint of the photonics die <NUM>. As such, optical signals propagating through the Faraday rotator <NUM> may be optically coupled to a bottom surface of the photonics die <NUM>.

After attachment of the photonics die <NUM> and the compute die <NUM>, the patch <NUM> may be assembled with an electronic system, such as the electronic system <NUM> in <FIG>. That is, the patch <NUM> may be arranged so that it overhangs an edge of an interposer. As such, room for attaching a connector (not shown in <FIG>) to a bottom of the housing <NUM> is provided.

Referring now to <FIG>, a cross-sectional illustration of an electronic system <NUM> is shown, in accordance with an additional embodiment according to the claims. In an embodiment, the electronic system <NUM> comprises a board <NUM>, such as a PCB. An interposer <NUM> is attached to the board <NUM> by interconnects <NUM>. A patch <NUM> is attached to the interposer <NUM> by interconnects <NUM>. The system level architecture of electronic system <NUM> may be substantially similar to the system level architecture of electronic system <NUM> in <FIG>. For example, the patch <NUM> may overhang an edge of the underlying interposer <NUM>.

In an embodiment, the patch <NUM> may comprise a core <NUM> with conductive routing layers <NUM> above and below the core <NUM>. Through core vias <NUM> may electrically couple the top routing layers <NUM> to the bottom routing layers <NUM>. In other embodiments, the patch <NUM> may be coreless. In an embodiment, a compute die <NUM> and a photonics die <NUM> are attached to the patch <NUM> by interconnects <NUM>. Interconnects <NUM> may be any suitable FLIs. The compute die <NUM> may be communicatively coupled to the photonics die <NUM> by a bridge <NUM> embedded in the top routing layers <NUM>.

The patch <NUM> comprises a Faraday rotator <NUM>. The Faraday rotator <NUM> may be integrated with the patch <NUM>. That is, instead of being a discrete component (as is the case in <FIG>), the Faraday rotator <NUM> is assembled as part of the patch <NUM> during fabrication of the patch <NUM>. Such an integrated process is described in greater detail below.

In an embodiment, the Faraday rotator <NUM> comprises a magnetic shell <NUM> and an optically clear core <NUM>. The magnetic shell <NUM> may be in direct contact with the routing layers <NUM> and the core <NUM>. That is, there may be no housing between the magnetic shell <NUM> and the substrate of the patch <NUM>. However, in other embodiments, a liner (not shown) may separate the magnetic shell <NUM> from the substrate of the patch <NUM>. In an embodiment, a lens <NUM> may be provided at a bottom of the Faraday rotator <NUM>. The lens <NUM> may be coupled to an optical cable <NUM>.

While there are no polarizers shown in <FIG>, it is to be appreciated that embodiments may comprise a pair of polarizers provided on opposite ends of the magnetic shell <NUM>. In other embodiments, the Faraday rotator <NUM> may be used without the polarizers.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a magnetic plug <NUM> is provided in the hole <NUM> is shown, in accordance with an embodiment. In the illustrated embodiment, the magnetic plug <NUM> may be in direct contact with the surfaces of the routing layers <NUM> and the core <NUM>, as shown in <FIG>. In other embodiments, a conductive liner may be disposed over the surfaces of the hole <NUM> prior to disposing the magnetic plug <NUM>. That is, in some embodiments, the magnetic plug <NUM> is separated from the routing layers <NUM> and the core <NUM> by a conductive layer, such as copper. In an embodiment, the magnetic plug <NUM> may be dispensed with any suitable process, such as, but not limited to, paste printing.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a second hole <NUM> is drilled through the magnetic plug <NUM> is shown, in accordance with an embodiment. In an embodiment, the drilling of the second hole <NUM> results in the plug <NUM> being transformed into a magnetic shell <NUM>. The magnetic shell <NUM> may have an outer diameter that is substantially equal to the diameter of the hole <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a plug <NUM> is provided in the second hole <NUM> is shown, in accordance with an embodiment. In an embodiment, the plug <NUM> may be an optically clear material. In an embodiment, the plug <NUM> may be disposed in the second hole <NUM> with a printing process or the like. The plug <NUM> and the magnetic shell <NUM> may structurally form a Faraday rotator <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the patch <NUM> after a lens <NUM>, a photonics die <NUM>, and a compute die <NUM> are attached to the patch <NUM> is shown, in accordance with an embodiment. In an embodiment, the lens <NUM> may be disposed over a bottom surface of the plug <NUM>. The lens <NUM> allows for incoming optical signals to be focused in order to improve efficiency.

In an embodiment, the photonics die <NUM> and the compute die <NUM> may be attached to the patch <NUM> by interconnects <NUM>. The interconnects are shown as solder balls, but it is to be appreciated that any FLI architecture may be used to connect the photonics die <NUM> and the compute die <NUM> to the patch <NUM>. In an embodiment, the photonics die <NUM> is communicative coupled to the compute die <NUM> by the bridge <NUM> embedded in the top routing layers <NUM>. In an embodiment, the photonics die <NUM> is positioned over the Faraday rotator <NUM>. That is, the Faraday rotator <NUM> is within a footprint of the photonics die <NUM>. As such, an optical signal passing through the Faraday rotator <NUM> may be optically coupled to a bottom surface of the photonics die <NUM>.

After attachment of the photonics die <NUM> and the compute die <NUM>, the patch <NUM> may be assembled with an electronic system, such as the electronic system <NUM> in <FIG>. That is, the patch <NUM> may be arranged so that it overhangs an edge of an interposer. As such, room for attaching a connector (not shown in <FIG>) to lens <NUM> is provided.

In <FIG>, the optical signal is coupled to the photonics die through a Faraday rotator that is positioned below the photonics die. Such an architecture requires overhanging the patch substrate over an edge of the interposer. However, embodiments are not limited to such architectures. For example, embodiments disclosed herein, not according to the claims, may also include providing the Faraday rotator above the photonics die. Examples of such embodiments are shown in <FIG>.

Referring now to <FIG>, a cross-sectional illustration of an electronic system <NUM> is shown, in accordance with an embodiment not according to the claims. In an embodiment, the electronic system <NUM> comprises a board <NUM> and a package substrate <NUM> attached to the board <NUM> by interconnects <NUM>. While shown as solder balls, the interconnects <NUM> may comprise any interconnect architecture, such as sockets. In an embodiment, one or more embedded bridges <NUM> may be provided in the package substrate <NUM>. The bridges <NUM> provide high density routing to communicatively couple photonics dies <NUM> to a compute die <NUM>. The photonics dies <NUM> and the compute die <NUM> may be coupled to the package substrate <NUM> by interconnects <NUM>. Interconnects <NUM> may comprise any FLI architecture. In an embodiment, an integrated heat spreader (IHS) <NUM> may be provided over the package substrate <NUM>. The IHS <NUM> may be thermally coupled to the compute die <NUM>. For example, a thermal interface material (TIM) (not shown) may be provided between the IHS <NUM> and the compute die <NUM>.

In an embodiment, Faraday rotators <NUM> may pass through the IHS <NUM> and be optically coupled to the photonics dies <NUM>. That is, the Faraday rotators <NUM> may be optically coupled to a top surface of the photonics dies <NUM>. In an embodiment, the Faraday rotator <NUM> may comprise a tubular housing <NUM>. A first polarizer <NUM> and a second polarizer <NUM> are provided in the housing <NUM>. A magnetic shell <NUM> may be provided between the first polarizer <NUM> and the second polarizer <NUM>. The magnetic shell <NUM> may be a permanent magnet in some embodiments. In the illustrated embodiment, the first polarizer <NUM> and the second polarizer <NUM> have a diameter that is substantially equal to an inner diameter of the magnetic shell <NUM>. In such an embodiment, the first polarizer <NUM> and the second polarizer <NUM> may be positioned within the magnetic shell <NUM>. However, in other embodiments, the first polarizer <NUM> and the second polarizer <NUM> may be on opposite ends of the magnetic shell <NUM> and be entirely outside the magnetic shell <NUM>. In an embodiment, an optically clear plug <NUM> may be provided within an inner diameter of the magnetic shell <NUM>.

The second polarizer <NUM> may be a vertical polarizer and the first polarizer <NUM> may be an angled polarizer (e.g., <NUM>°). That is, the first polarizer <NUM> may be different than the second polarizer <NUM>. In an embodiment, the magnetic shell <NUM> has a magnetic field that modifies the orientation of the incoming vertically polarized light. For example, the magnetic shell <NUM> may result in <NUM>° polarized light in some embodiments.

In an embodiment, a first lens <NUM> may be provided within the housing <NUM>. The lens <NUM> improves optical coupling between the Faraday rotator <NUM> and the photonics die <NUM>. In an embodiment, a connector <NUM> is provided over and around an end of the housing <NUM>. The connector <NUM> may be tubular and surround an end of the housing <NUM>. The connector <NUM> may comprise a second lens <NUM> to focus optical signals coming into the Faraday rotator <NUM>. The connector <NUM> may provide mechanical coupling of an optical fiber <NUM> to the Faraday rotator <NUM>.

Referring now to <FIG>, a cross-sectional illustration of an electronic system <NUM> is shown, in accordance with an additional embodiment not according to the claims. In an embodiment, the electronic system <NUM> in <FIG> is substantially similar to the electronic system <NUM> in <FIG>, with the exception of there being a different magnet configuration in the Faraday rotator <NUM>. Instead of providing a permanent magnet shell, a conductive coil <NUM> is provided between the first polarizer <NUM> and the second polarizer <NUM>. The conductive coil <NUM> may be an electromagnet that is connected to a power source (not shown). Controlling the current that passes through the conductive coil <NUM> allows for a controllable magnetic field to be provided around the plug <NUM>. As such, the incoming optical signal can have a tunable light polarization.

In <FIG> and <FIG>, the Faraday rotators are discrete components that are assembled with the electronic systems <NUM>. However, it is to be appreciated that various components of the Faraday rotator may also be fabricated in-situ with the assembly of the photonics die. An example of such an embodiment is shown in <FIG>.

Referring now to <FIG>, a cross-sectional illustration of a portion of a photonics die <NUM> embedded in a dielectric layer <NUM> is shown, in accordance with an embodiment. In an embodiment, an opening <NUM> may be provided through the dielectric layer <NUM> to expose a top surface of the photonics die <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the photonics die <NUM> after a lens <NUM> is formed is shown, in accordance with an embodiment. In an embodiment, the lens <NUM> may be disposed over the exposed top surface of the photonics die <NUM>. The lens <NUM> may be formed by dispensing a liquid polymer droplet over the exposed top surface of the photonics die <NUM>. The liquid polymer droplet may then be cured to lock in the shape of the lens <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the photonics die <NUM> after a Faraday rotator <NUM> is attached is shown, in accordance with an embodiment. In an embodiment, the Faraday rotator <NUM> may be attached to the dielectric layer <NUM> by an adhesive <NUM>. For example, typical die mounting processes may be used to attach the Faraday rotator <NUM> to the dielectric layer <NUM>.

In an embodiment, the Faraday rotator <NUM> may comprise a housing <NUM>. The housing <NUM> may be a tubular housing in some embodiments. A first polarizer <NUM> and a second polarizer <NUM> may be provided within the housing <NUM>. In an embodiment, a magnetic shell <NUM> may be provided between the first polarizer <NUM> and the second polarizer <NUM>. The magnetic shell <NUM> may be a permanent magnet. However, in other embodiments, the magnetic shell <NUM> may be replaced with a conductive coil, similar to the embodiment shown in <FIG>. In an embodiment, the magnetic shell <NUM> may be entirely between the first polarizer <NUM> and the second polarizer <NUM>. In other embodiments, the first polarizer <NUM> may be at a first end of the magnetic shell <NUM> and surrounded by the magnetic shell <NUM>, and the second polarizer <NUM> may be at a second end of the magnetic shell <NUM> and surrounded by the magnetic shell <NUM>. In an embodiment, an optically clear plug <NUM> may be provided within the magnetic shell <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the photonics die <NUM> after a connector <NUM> is disposed over the Faraday rotator <NUM> is shown, in accordance with an embodiment. The connector <NUM> may be tubular and fit around the housing <NUM>. In an embodiment, a lens <NUM> may be provided in the connector <NUM>.

In an embodiment, a portion of the Faraday rotator <NUM> may pass through an IHS (not shown) above the photonics die <NUM>. In other embodiments, the Faraday rotator <NUM> may be entirely below the IHS, with only an optical cable passing through the IHS.

<FIG> illustrates a computing device <NUM> in accordance with one implementation of the invention. The computing device <NUM> houses a board <NUM>. The board <NUM> may include a number of components, including but not limited to a processor <NUM> and at least one communication chip <NUM>. The processor <NUM> is physically and electrically coupled to the board <NUM>. In some implementations the at least one communication chip <NUM> is also physically and electrically coupled to the board <NUM>. In further implementations, the communication chip <NUM> is part of the processor <NUM>.

These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth).

The processor <NUM> of the computing device <NUM> includes an integrated circuit die packaged within the processor <NUM>. In some implementations of the invention, the integrated circuit die of the processor may be part of an electronic system with a photonics die that is optically coupled to a Faraday rotator, in accordance with embodiments described herein. The term "processor" may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.

Claim 1:
A photonics package, comprising:
an interposer (<NUM>; <NUM>);
a patch (<NUM>; <NUM>) over the interposer (<NUM>; <NUM>), wherein the patch (<NUM>; <NUM>) overhangs an edge of the interposer (<NUM>; <NUM>);
a photonics die (<NUM>; <NUM>) on the patch (<NUM>; <NUM>); and
a Faraday rotator (<NUM>; <NUM>) passing through a thickness of the patch (<NUM>; <NUM>), wherein the Faraday rotator (<NUM>; <NUM>) is below the photonics die (<NUM>; <NUM>).