1. An optical interposer for providing optimal optical coupling between an optical transceiver interface and an external optical interface, the optical interposer comprising:

an interposer Photonic Integrated Circuit (PIC) operably configured to couple optical signals between the optical transceiver interface and the external optical interface;

one or more waveguide-based optical devices operably integrated on a common substrate; and

a plurality of interposer input/output (I/O) channels operably configured as transceiver PIC input/output (I/O) channels having the optical transceiver interface and the external optical interface.

2. The optical interposer of claim 1, wherein the optical transceiver interface is a transceiver Photonic Integrated Circuit (PIC).

3. The optical interposer of claim 1, wherein the common substrate is a semiconductor substrate.

4. The optical interposer of claim 1 wherein the external optical interface is any one of an optical fiber, an optical fiber array, a Planar Lightwave Circuit (PLC), and a free space optical system.

5. The optical interposer of claim 2, wherein the optical interposer is located between the transceiver Photonic Integrated Circuit (PIC) and the external optical interface.

6. The optical interposer of claim 1, wherein the optical interposer is operable as a semiconductor chip.

7. The optical interposer of claim 1, wherein the optical interposer is operable as an optical mode size converter between the transceiver PIC input/output (I/O) channel and the external optical interface.

8. The optical interposer of claim 1, wherein the optical interposer is operable as a polarization selector and/or a polarization switch.

9. The optical interposer of claim 1, wherein the optical interposer is operable as a polarization rotator.

10. The optical interposer of claim 1, wherein the optical interposer is operable to function as a routing light circuit to distribute pitch.

11. The optical interposer of claim 1, wherein the optical interposer is operable as a polarizing beam splitter.

12. The optical interposer of claim 1, wherein the optical interposer is operable to function as an optical Multiplexer (MUX) and/or an optical demultiplexer (deMUX).

13. The optical interposer of claim 12 wherein the optical Multiplexer (MUX) is operably configured to receive a plurality of optical signals from a transceiver Photonic Integrated Circuit (PIC), multiplexing the plurality of optical signals into a single signal.

14. The optical interposer of claim 12 wherein the optical demultiplexer (deMUX) receives a single signal from the external optical interface and demultiplexes the single signal into a plurality of signals.

15. The optical interposer of claim 1, wherein the optical interposer further comprises an angled interposer interface.

16. The optical interposer of claim 1, wherein the optical interposer further comprises an angled interposer waveguide.

17. The optical interposer of claim 1 wherein the interposer waveguide has a refractive index value between the transceiver photonic integrated circuit waveguide value and the external optical interface waveguide value.

18. The optical interposer of claim 1, wherein the optical interposer further comprises a plurality of external optical interfaces.

19. The optical interposer of claim 1, wherein the optical interposer is operably configured to provide optimal optical coupling with a plurality of transceiver PIC input/output (I/O) channels and a plurality of external optical channels.

Background

The rapid growth of cloud computing and artificial intelligence applications is driving internet technology to construct powerful data centers. To date, building large data centers is more cost effective and less complex than building large, medium-scale data centers to expand processing capacity. However, in order to transfer a large amount of data at an ultra high speed between server nodes/racks in a data center, a high transmission bandwidth is required. Traditionally, interconnections have been achieved by sending and receiving data in the form of electrical signals using copper cables and electrical transceivers. Such electrical solutions are very bulky and transmit distances of less than 20 meters (m) at data rates of 10 gigabits per second (Gbps).

An optical interposer is a Photonic Integrated Circuit (PIC) that includes one or more waveguide-based optical devices integrated on a common substrate, typically a semiconductor substrate. The interposer PIC is used to couple optical signals between an optical transceiver interface (e.g., a PIC waveguide) and an external optical interface (e.g., a fiber, fiber array, Planar Lightwave Circuit (PLC), or free space optical system).

Fiber optic networks have replaced copper-based networks for many years in view of the obvious advantages of optical solutions in terms of smaller footprint and longer transmission distances (up to 300m at 50 Gbps). Conventional optical transceivers of data centers are Mostly Multimode Fiber (MMF). Typical multimode fiber links have data rates of 10 megabits per second (Mbps) to 10Gbps over link lengths of up to only 600 m. However, it is not uncommon for node interconnections in today's jumbo data centers to easily exceed distances of 500m to 2 km. Therefore, there is a strong need for single mode transceivers for single mode optical transmission connecting optical fibers between nodes. Conventional single mode transceivers consist of many high cost discrete optical components. They have a large footprint and require costly assembly processes and maintenance.

With the advent of silicon photonics (SiPh) technology, the potential for low cost and small footprint solutions for large scale implementation of interconnects in excess of 500m to 2km has increased. SiPh technology employs the state-of-the-art Complementary Metal Oxide Semiconductor (CMOS) casting process to fabricate Photonic Integrated Circuit (PIC) devices, in which most of the optical components are integrated on a single silicon chip. However, the optical mode size (spot size of light in the waveguide) of the input/output (I/O) port of a SiPh chip (also known as a Si PIC) is about 1 μm, while the Single Mode Fiber (SMF) is about 10 μm. Such large differences in optical mode size introduce large optical power losses in the butt-coupling (head-to-head coupling between the Si PIC I/O port and the SMF). The optical power loss of conventional coupling methods from the PIC to the fiber, PLC (planar lightwave circuit) and edge-emitting laser diodes is very high (over 50%).

The main reason is that the optical mode size of the waveguides in the PIC is much smaller than that of optical fibers, PLCs and laser diodes. Conventional coupling methods use discrete free-space optical components (e.g., miniature lenses) to convert the light mode size. This high cost approach is not a viable solution to this problem. Unless this coupling problem is solved, the SiPh technique will not be a solution for large-scale implementation of SMF interconnects.

Accordingly, the present invention is directed to an optical interposer for optimal optical coupling of an optical transceiver interface and an external optical interface that overcomes the above-mentioned disadvantages of the prior art.

Disclosure of Invention

The foregoing objects of the invention are achieved by employing an optical interposer that couples an optical signal between an optical transceiver interface and an external optical interface. In particular, the optical interposer comprises: an interposer Photonic Integrated Circuit (PIC) operably configured/adapted to couple optical signals between an optical transceiver interface and an external optical interface; one or more waveguide-based optical devices operably integrated on a common substrate; and one or more interposer input/output (I/O) channels operatively configured/adapted with the transceiver PIC input/output (I/O) channels of the optical transceiver interface and the external optical interface.

According to an embodiment of the invention, the optical transceiver interface is a transceiver Photonic Integrated Circuit (PIC).

According to an embodiment of the invention, the common substrate is a semiconductor substrate.

According to an embodiment of the present invention, the external optical interface is any one of an optical fiber, an optical fiber array, a Planar Lightwave Circuit (PLC), a free space optical system, and the like.

In accordance with an embodiment of the present invention, an optical interposer is located between a transceiver Photonic Integrated Circuit (PIC) and an external optical interface.

According to an embodiment of the present invention, an optical interposer is operable as a semiconductor chip.

In accordance with an embodiment of the present invention, the optical interposer is operable as an optical mode size converter between a transceiver PIC input/output (I/O) channel and an external optical interface.

According to embodiments of the present invention, the optical interposer is operable to function as a polarization selector and/or a polarization switch.

According to embodiments of the present invention, the optical interposer is operable to function as a polarization rotator.

According to embodiments of the present invention, an optical interposer is operable as a routing circuit to distribute pitch.

According to embodiments of the present invention, the optical interposer is operable to function as a polarizing beam splitter.

According to embodiments of the present invention, the optical interposer is operable to function as an optical Multiplexer (MUX) and/or an optical demultiplexer (deMUX).

In accordance with an embodiment of the present invention, an optical Multiplexer (MUX) is operably configured/adapted to receive one or more optical signals from a transceiver Photonic Integrated Circuit (PIC), multiplexing the one or more optical signals into a single signal.

According to an embodiment of the invention, an optical demultiplexer (deMUX) receives a single signal from an external optical interface and demultiplexes the single signal into one or more signals.

According to embodiments of the present invention, the optical interposer further comprises an angled interposer interface.

According to embodiments of the present invention, the optical interposer further comprises an angled interposer waveguide.

According to embodiments of the present invention, the interposer waveguide has a refractive index value between the transceiver photonic integrated circuit waveguide value and the external optical interface waveguide value.

According to embodiments of the present invention, an optical interposer is connected to one or more external optical interfaces.

In accordance with an embodiment of the present invention, the optical interposer is operably configured/adapted to provide optimal optical coupling (and/or optical connection) with one or more transceiver PIC input/output channels and one or more external optical channels.

Drawings

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1A is a schematic diagram showing a top view of an optical interposer according to an embodiment of the present invention;

FIG. 1B is a schematic diagram showing a side view of an optical interposer according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating an optical interposer with an external optical interface according to one embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an optical interposer with an external optical interface according to another embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an optical interposer with an external optical interface according to yet another embodiment of the present invention;

FIG. 5 is a schematic diagram of an optical interposer showing Transverse Electric (TE) polarization and Transverse Magnetic (TM) polarization according to one embodiment of the present invention;

FIG. 6 is a schematic diagram of an optical interposer showing Transverse Electric (TE) polarization according to another embodiment of the present invention;

FIG. 7 is a schematic diagram of an optical interposer showing Transverse Magnetic (TM) polarization according to yet another embodiment of the present invention;

FIG. 8 is a schematic diagram of an interposer Photonic Integrated Circuit (PIC) showing optical signal coupling between a plurality of transceiver PIC input/output (I/O) channels and a plurality of external channels, in accordance with an embodiment of the present invention;

FIG. 9 is a schematic diagram illustrating an optical interposer for multiplexing and/or demultiplexing optical signals in accordance with an embodiment of the present invention;

FIG. 10 shows a schematic diagram of an optical interposer connected to a plurality of external optical interfaces in accordance with an embodiment of the present invention;

FIG. 11 illustrates an optical interposer to transceiver Photonic Integrated Circuit (PIC) interposer interface in accordance with one embodiment of the present invention;

FIG. 12 illustrates an angled interposer interface of an optical interposer to external optical interface according to another embodiment of the present invention;

FIG. 13 illustrates an angled waveguide on an optical interposer interface to a transceiver Photonic Integrated Circuit (PIC) in accordance with one embodiment of the present invention;

fig. 14 illustrates angled waveguides at an optical interposer interface to an external optical interface according to another embodiment of the present invention.

Component list

Optical interposer-100

Interposer photonic integrated circuit (Pic) -105

Optical transceiver interface-110

Transceiver photonic circuit-115

External optical interface-120

Interposer waveguide-125

Interposer input/output (I/O) channel-130 for optical transceiver interface

Interposer input/output (I/O) channel-135 for external optical interface

Transceiver PIC input/output (I/O) channel-140

Transceiver waveguide-145

Optical fiber-150

Optical fiber array-155

Planar Lightwave Circuit (PLC) -160

Free space optical System-165

External PLC Circuit-170

External optical path-175

For convenience and a better understanding of the exemplary examples in the various embodiments of the invention, the following reference numerals may be used interchangeably:

transceiver Photonic Integrated Circuit (PIC) -110

Detailed Description

The present invention relates to an optical interposer that is operably configured/adapted to provide optimal optical coupling (and/or optical connection) between an optical transceiver interface and an external optical interface.

The principles of the present invention and its advantages are best understood by referring to fig. 1A-14. In the following detailed description of illustrative or exemplary embodiments of the disclosure, specific embodiments in which the disclosure may be practiced are described in sufficient detail to enable those skilled in the art to practice the disclosed embodiments.

The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents. Reference in the specification to "one embodiment," "an embodiment," "embodiments," or "one or more embodiments" is intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure.

Fig. 1A and 1B show schematic top and side views of an optical interposer according to one or more embodiments of the present invention. In particular, optical interposer 100 includes an interposer Photonic Integrated Circuit (PIC)105, one or more waveguide-based optical devices having interposer waveguides 125, and one or more interposer input/output (I/O) channels (130 and/or 135).

The interposer Photonic Integrated Circuit (PIC)105 is operably configured/adapted to couple optical signals between the optical transceiver interface 110 and the external optical interface 120.

The waveguide-based optical device with the interposer waveguide 125 is integrated on a common substrate. In particular, the common substrate is a semiconductor substrate.

The interposer input/output (I/O) channels 130 are operably configured/adapted with transceiver PIC input/output (I/O) channels 140 of the optical transceiver interface 110. Also, an interposer input/output (I/O) channel 135 is also operatively configured/adapted with the external optical interface 120.

According to an embodiment of the invention, the optical transceiver interface 110 is a transceiver Photonic Integrated Circuit (PIC) 110. The transceiver Photonic Integrated Circuit (PIC)110 also includes a transceiver photonic circuit 115, a transceiver waveguide 145, and a transceiver PIC input/output (I/O) channel 140.

According to an embodiment of the present invention, the external optical interface 120 is any one of an optical fiber 150, an optical fiber array 155, a Planar Lightwave Circuit (PLC)160, a free-space optical system 165, and the like.

Referring to fig. 1A and 1B, optical interposer 100 includes a transceiver Photonic Integrated Circuit (PIC)110 and an array of optical fibers 155 in an external optical interface 120.

In accordance with an embodiment of the present invention, optical interposer 100 is operably positioned between transceiver Photonic Integrated Circuit (PIC)110 and external optical interface 120 to provide optimal optical coupling between transceiver Photonic Integrated Circuit (PIC)110 and external optical interface 120.

In accordance with an embodiment of the present invention, the optical interposer 100 is operable as a semiconductor chip to provide a bridge between a transceiver Photonic Integrated Circuit (PIC)110 and an external optical interface 120. In particular, the bridge provides specific connections to the external optical interface 120 with different functions. Furthermore, optical interposer 100 serves as a semiconductor chip that is independent of a functional Photonic Integrated Circuit (PIC) that is assembled as an extension of transceiver Photonic Integrated Circuit (PIC) 110.

In accordance with an embodiment of the present invention, the optical interposer 100 is operable as an optical mode size converter for optimal optical coupling (or optical connection) with a transceiver Photonic Integrated Circuit (PIC) 110. In particular, as shown in fig. 1A, the optical interposer 100 acts as an optical mode size converter between a transceiver PIC input/output (I/O) channel 140 and an external optical interface 120, such as an optical fiber 150. In addition, the waveguide-based optics each have an edge for optimal optical coupling (or optical connection) with the transceiver Photonic Integrated Circuit (PIC)110, and the optical mode shape in the waveguide-based optics is adjusted to output the appropriate optical mode for coupling into an external optical interface, typically with larger optical mode sizes.

Fig. 2, 3, and 4 show schematic diagrams of an optical interposer connected to an external optical interface according to one or more embodiments of the present invention. In particular, in fig. 2, 3 and 4, the external optical interfaces are an optical fiber 150, a Planar Lightwave Circuit (PLC)160 and a free space optical system 165, respectively.

In accordance with embodiments of the present invention, as shown in fig. 1A, 2, 3, and 4, the optical interposer 100 is operable to match the pitch configuration of transceiver Photonic Integrated Circuit (PIC) input/output (I/O) channels 140 and the external optical interface 120 to reduce the size of the waveguide-based optical device and simplify the multi-channel device.

FIG. 5 is a schematic diagram of an optical interposer showing Transverse Electric (TE) polarization and Transverse Magnetic (TM) polarization according to one embodiment of the present invention. In particular, the optical interposer 100 selects an input optical signal based on the TE polarization/TM polarization and outputs the TE mode optical signal and the TM mode optical signal to different output ports. The fiber array 155 has a pair of optical I/Os, referred to as Tx/Rx. The optical interposer 100 provides a bridge connecting the transceiver Photonic Integrated Circuit (PIC)110 and the optical fiber array 155 for transmitting Tx signals from the transceiver Photonic Integrated Circuit (PIC)110 to the optical fiber array 155. In addition, to receive signals from the array of fiber arrays 155, light is combined with TE and TM modes.

According to embodiments of the present invention, optical interposer 100 is operable as a polarizing beam splitter. In particular, the optical interposer selects the TE and TM modes, and is directed to different ports and coupled back to the receiver side of the transceiver Photonic Integrated Circuit (PIC) 110.

In the PIC/PLC scenario, TE polarization refers to the electric field of the optical mode that is substantially parallel to the plane and perpendicular to the direction of propagation. And, TM polarization refers to the electric field of an optical mode that is substantially perpendicular to the plane and the direction of propagation.

FIG. 6 is a schematic diagram of an optical interposer showing Transverse Electric (TE) polarization according to another embodiment of the present invention. In particular, the waveguide-based optics on the interposer Photonic Integrated Circuit (PIC)105 are operably configured/adapted to select an input optical signal based on TE/TM polarization and also to switch the input TM mode optical signal to a TE mode optical signal. Although the TE and TM modes are selectively directed to two different ports, the TM mode is rotated to the TE mode during propagation in the optical interposer 100. Thus, the output port contains the TE optical signal.

FIG. 7 is a schematic diagram of an optical interposer showing Transverse Magnetic (TM) polarization according to yet another embodiment of the present invention. The waveguide-based optics on the interposer Photonic Integrated Circuit (PIC)105 are operably configured/adapted to select an input optical signal based on TE/TM polarization and also switch the input TE mode optical signal to a TM mode optical signal. Although the TE and TM modes are selectively directed to two different ports, the TE mode is rotated to the TM mode during propagation in the optical interposer 100. Thus, the output port contains the TM optical signal.

According to an embodiment of the present invention, optical interposer 100 is operable as a polarization selector.

According to an embodiment of the present invention, the optical interposer 100 is operable to function as a polarization switch.

According to an embodiment of the present invention, the optical interposer 100 is operable to function as a polarization rotator.

According to embodiments of the present invention, an optical interposer is operable as a routing circuit to distribute pitch.

Fig. 8 is a schematic diagram of an interposer Photonic Integrated Circuit (PIC) showing coupling of optical signals in accordance with an embodiment of the present invention. In particular, the waveguide-based optics on optical interposer 100 are operably configured/adapted to couple optical signals between a plurality of transceiver PIC input/output (I/O) channels and a plurality of external channels. In addition, multi-channel coupling provides a routing path for the photonic integrated circuit to have the output channels with a programmable pitch for coupling to external optical interfaces.

Fig. 9 is a schematic diagram illustrating an optical interposer for multiplexing and/or demultiplexing optical signals according to an embodiment of the present invention.

According to an embodiment of the present invention, on the transmitter side, optical interposer 100 receives multiple optical signals from transceiver Photonic Integrated Circuit (PIC)110, multiplexes the multiple optical signals into a single signal, and outputs the single signal to external optical interface 120.

According to an embodiment of the present invention, the optical interposer receives a single signal from the external optical interface 120, demultiplexes it into several signals, and directs it to the transceiver Photonic Integrated Circuit (PIC) 110. Thus, the number of input/output (I/O) channels in the external optical interface 120 is reduced.

In accordance with an embodiment of the present invention, the optical interposer 100 is operable to function as an optical Multiplexer (MUX) and/or an optical demultiplexer (deMUX) to allow the fabrication of passive devices with lower phase errors, lower internal propagation losses and higher manufacturing tolerances and lower thermal sensitivity.

FIG. 10 shows a schematic diagram of an optical interposer that also includes a plurality of external optical interfaces, according to an embodiment of the present invention. In particular, the plurality of external optical interfaces is not limited to one edge of the optical interposer.

According to embodiments of the present invention, multiple channels serve one of the above functions, such as, but not limited to, optical mode size converters, splitters/combiners, wavelength filters, polarization splitters, polarization rotators, and optical multiplexers/demultiplexers.

Fig. 11 and 12 illustrate an interposer interface of an optical interposer relative to a transceiver Photonic Integrated Circuit (PIC)110 and an external optical interface 120 in accordance with one or more embodiments of the present invention. In particular, the interposer interface is an angled interposer interface. In addition, the angled interposer interface is laterally polished at an angle to minimize back reflections.

Fig. 13 and 14 illustrate interposer interfaces to transceiver Photonic Integrated Circuits (PICs) 110 and external optical interfaces 120 in accordance with one or more embodiments of the present invention. In particular, the interposer interface is not intentionally angled, and the waveguide is adjustably tilted at a particular angle to achieve a non-angled interface and to achieve the same effect of minimizing backreflections.

According to embodiments of the present invention, the refractive index value of the interposer waveguide is between the transceiver photonic integrated circuit waveguide value and the external optical interface waveguide value (or optical path in free space).

Accordingly, embodiments of the present invention provide an optical interposer for optimal coupling of optical signals (and/or optical connections) between an optical transceiver interface and an external optical interface. In particular, optical interposers have higher alignment tolerances, lower waveguide propagation losses, higher performance, lower internal propagation losses, and higher manufacturing tolerances.

Although the present invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that various changes and modifications may be made without departing from the scope of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In other words, it is contemplated to cover any and all modifications, variations, or equivalents that fall within the scope of the basic underlying principles and whose essential attributes are claimed in this patent application. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention are capable of operation in other sequences than described or illustrated herein or otherwise described and with respect to the orientation illustrated herein.