Optical modules

Abstract

There is provided an optical device. The optical device comprises a first substrate layer (302), a first optical layer (304), and a first coupling portion. The first optical layer (304) comprises a photonic circuit. The first optical layer (304) is located above the first substrate layer (302). The first coupling portion is at least partially formed by a first opening (306) in the first substrate layer (302). The first opening (306) exposes a first optical connector (308) located above the first opening (306). The first optical connector (308) is adapted to optically couple the optical device to an optical printed circuit board (PCB). The first opening (306) is adapted to accept a second coupling portion of the optical PCB.

Description

[0001] OPTICAL MODULES

[0002] Technical Field

[0003] The present disclosure relates to an optical device, an optical printed circuit board (PCB), a system comprising an optical device and an optical PCB, and methods of fabricating the optical device, the optical PCB, and the system.

[0004] Background

[0005] In recent years there has been development of technologies related to electrical and optical packaging, such as co-packaged optics (CPOs) and optical waveguides being embedded in layers of an optical printed circuit board (PCB). Co-packaging, in relation to optics, is a term used to describe the practice of integrating a digital integrated circuit (IC), such as an application specific IC (ASIC), or an application-specific standard product (ASSP), and optical elements in the same packaging. The optical elements in the packaging can include optical engines which convert electrical signals into optical signals, and vice versa. The resulting optical signals are capable of travelling long distances without being affected by the typical issues associated with electrical lines, such as signal loss and electromagnetic (EM) interference. This characteristic of optical signals is convenient, especially for high frequency signals. In general, for co-packaged optics, the electrical connection between the digital IC and the optical engine is relatively short, to preserve signal integrity.

[0006] The use of co-packaged optical modules is, at present, driven by advancements in the datacom industry, however the technology requirements for datacom applications and telecommunications applications differ.

[0007] Figure 1 represents a typical data center configuration of a co-packaged ASIC (e.g. a switch) surrounded by optical engines. In more detail, as can be seen from Figure 1 , the ASIC is positioned in the center of a package and is surrounded by the optical engines. The configuration illustrated in Figure 1 is a common example of a co-packaged optics configuration used in data centers. Although not illustrated in Figure 1 , the interconnection to the next package can be several meters away, and the optical connection to the next package can be made using optical fibers. One significant difference between datacom applications and radio applications is the density of modules to interconnect. Figure 2 is an illustration of an optical PCB used in a datacom application scenario. As can be seen from Figure 2, the ASIC density (e.g. in terms of number of ASICs per unit of area) is relatively high. For example, the ASICs of Figure 2 may only be separated by distances of up to a few centimeters. The high ASIC density an present challenges for PCB design. There are some existing techniques which seek to provide a more efficient and compact configuration for PCB design.

[0008] For example, some existing techniques rely on technology related to fiber foil, glass devices containing waveguides (i.e. to be placed on top of a PCB), and polymer waveguides or glass layers embedded in ‘regular’ PCB layers. A PCB embedded with a polymer waveguide and / or glass layers is commonly referred to as an optical PCB or an electro-optical PCB. The use of optical PCBs is advantageous since their design is relatively compact, and they are suitable for applications involving high device density. Moreover, optical PCB technology allows for both optical lines and electrical lines to be integrated in the same board.

[0009] However, while the fabrication of embedded waveguides is already compatible with production processes of standard electrical PCBs, the assembly of optical modules on the board is more challenging and needs to be adapted for industrial assembly processes (e.g. such that any changes to the process are acceptable for implementation). In particular, a key challenge for assembly of optical modules for optical PCBs is ensuring proper alignment of (e.g. electrical) pads and optical ports. With regards to optical ports, many optical modules utilize fiber connectors. However, the utilization of fiber connectors causes unnecessary volume occupation, and requires the implementation of an additional process step for mounting the fibers after reflow soldering (i.e. since fibers are not reflow solderable). As such, standard fiber connectors are space inefficient and cancel out the advantage of an optical PCB’s compact design when used in dense interconnect scenarios. Therefore, the use of fiber connectors is disadvantageous when applied to an optical PCB implementation.

[0010] As such, it is desirable to develop a technique for configuring an optical PCB that does not rely on fiber. A currently existing technique for configuring an optical connection involves a packaging with apertures and solder balls on a bottom side of the package. This arrangement allows for optical input and output using parabolic mirrors that are mounted in an optical PCB. However, this existing technique has a drawback associated with alignment precision. Indeed, with parabolic mirrors and lenses, a misalignment of a few microns can cause a power loss in the range of a few decibels (dBs).

[0011] A number of options have been proposed to deal with this issue of misalignment and consequent power loss. One option is to use vertical emitting lasers (e.g. vertical-cavity surface-emitting laser (VCSEL)), that produce a vertical light beam which is easier to focus. However, this option limits the choice of laser source wavelength to 850nm, which is not currently used in certain optical implementations, posing the problem of interoperability. Additionally, VCSELs are directly modulated, which means that is not possible to disaggregate the laser from the modulator (e.g. to choose a better thermal environment for the laser). Moreover, directly modulated lasers have lower data rates than external optical modulators. As such, there are multiple drawbacks associated with the use of vertical emitting lasers.

[0012] Another proposed option to deal with the above-mentioned issue of misalignment and consequent power loss is to use very large (e.g. 250um) optical waveguides that propagate multiple optical modes. However, the use of large multi-mode waveguides brings further constraints. For example, multi-mode waveguides are not compatible with optical systems based on single mode fiber. Moreover, multi-mode waveguides suffer modal dispersion and thus their maximum length depends on data rate. In contrast, single mode waveguides do not have a significant dependence on data rate.

[0013] As such, there currently exists certain challenges associated with the configuration of optical modules and optical PCBs, and how said entities can be used in combination (e.g. assembled).

[0014] As mentioned above, there are certain challenges associated with existing configurations of optical modules and optical PCBs. Indeed, although optical PCBs provide the potential for increased space efficiency, current techniques for optical PCB and optical module assembly are restrictive. For example, existing techniques rely on the use of vertically emitting lasers and / or large optical waveguides, which limits the operability of the optical PCB.

[0015] It is therefore an objective of the disclosure to provide techniques which enable more (e.g. space) efficient and compact optical interconnection between an optical device and an optical PCB. It is a further objective of the discourse to provide a technique which does not rely on fiber connections, and which allows proper (e.g. optical alignment) of an optical module and optical PCB.

[0016] Therefore, according to an aspect of the disclosure, there is provided an optical module. The optical module comprises a first substrate layer. The optical module also comprises a first optical layer comprising a photonic circuit. The first optical layer is located above the first substrate layer. The optical module comprises a first coupling portion. The first coupling portion is at least partially formed by a first opening in the first substrate layer. The first opening exposes a first optical connector located above the first opening. The first optical connector is adapted to optically couple the optical device to an optical printed circuit board (PCB). The first opening is adapted to accept a second coupling portion of the optical PCB.

[0017] According to another aspect of the disclosure, there is provided an optical PCB. The optical PCB comprises a second substrate layer. The optical PCB also comprises a second optical layer comprising one or more optical channels. The second optical layer is located above the second substrate layer. The optical PCB also comprises a second coupling portion. The second coupling portion comprises a second optical connector adapted to optically couple the optical PCB to an optical device. The second coupling portion is adapted to protrude into a first opening of the optical device.

[0018] According to another aspect the disclosure, there is provided a system. The system comprises an optical device as referred to herein and an optical PCB. The optical PCB may be an optical PCB as referred to herein.

[0019] According to another aspect of the disclosure, there is provided a method of fabricating an optical device as referred to herein.

[0020] According to another aspect of the disclosure, there is provided a method of fabricating an optical PCB as referred to herein.

[0021] According to another aspect of the disclosure, there is provided a method of fabricating a system (e.g. assembly) as referred to herein. Thus, in the manner described above, improved configurations for an optical PCB and an optical device (e.g. for mounting on the optical PCB) are provided. Advantageously, the configuration of the optical device and the optical PCB enable a direct connection between the optical device and optical PCB. Indeed, the optical device and optical PCB described herein provide for an optical coupling technique which is compact and utilizes space efficiently. Moreover, the configuration of the coupling portions of the optical device and optical PCB allow for easy (e.g. optical) alignment between the optical device and optical PCB. In this way, the optical elements (e.g. pins) of the optical device are more effectively coupled to the optical elements (e.g. optical lines) of the optical PCB. The configurations of each of the optical device and the optical PCB enables a coupling technique that is beneficially compatible with single mode waveguides and (e.g. laser) light sources (e.g. that use an external optical modulator), and the use of light sources in the O and C band.

[0022] Brief description of the drawinos

[0023] For a better understanding of the techniques, and to show how they may be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

[0024] Figures 1 and 2 are schematic illustrations of existing configurations of optical modules;

[0025] Figures 3A, 3B, and 3C are schematic illustrations of an optical device according to some embodiments;

[0026] Figures 4A and 4B are schematic illustrations of an optical PCB according to some embodiments;

[0027] Figures 5 to 7 are schematic illustrations of an optical device according to some embodiments;

[0028] Figures 8 to 10 is a schematic illustration of components of a system according to an embodiment;

[0029] Figure 11 is a schematic illustration of evanescently coupled waveguides;

[0030] Figure 12 is a schematic illustration of an optical connector according to an embodiment; Figures 13 to 17 are schematic illustrations of components of a system according to some embodiments; and

[0031] Figures 18 to 20 are block diagrams illustrating methods performed according to some embodiments.

[0032] Detailed Description

[0033] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0034] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject-matter disclosed herein, the disclosed subject-matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject-matter to those skilled in the art.

[0035] Figures 3A, 3B and 3C are schematic illustrations of an optical device according to an embodiment. More specifically, Figure 3A illustrates a perspective view of a top portion of the optical device. Figures 3B and 3C illustrate different perspective views of a first coupling portion of the optical device. Figure 3B illustrates a lateral (side) view of the first coupling portion, and Figure 3C illustrates a view of the bottom of the first coupling portion. The optical device referred to herein may be, for example, an electro-optical device, such as an optical package. For example, the optical device may be a copackaged optical (CPO) device, or a near-packaged optical (NPO) device.

[0036] As illustrated in Figure 3A, the optical device comprises a first substrate layer 302 and a first optical layer 304. The first substrate layer 302 may be referred to herein as a laminate layer. The first substrate layer 302 may be made of any kind of substrate material. For example, the first substrate layer 302 may be made of fiberglass and / or epoxy. As illustrated in Figure 3A, the first substrate layer 302 may comprise a (e.g. rigid) board. In some examples, the first substrate layer 302 may be adapted to give the optical device a rigid form. The first substrate layer 302 may be understood to be a base layer on which one or more components (e.g. the first optical layer 304) may be deposited. The first substrate layer 302 may be referred to herein as a bottom layer of the optical device.

[0037] As illustrated in Figure 3A, the first optical layer 304 is located above the first substrate layer 302. In some examples, the first optical layer 304 may be coupled (e.g. directly or indirectly) to the first substrate layer 302. The first optical layer 304 may comprise a (e.g. optical) die. For example, the first optical layer 304 may be an optical die. Alternatively, or in addition, the first optical layer 304 may comprise semiconductor material, such as silicon. For example, the first optical layer 304 may be at least partially made from the semiconductor material. In some examples, the first optical layer 304 may comprise a silicon die. Although not explicitly illustrated in Figure 3A, the first optical layer 304 comprises a photonic circuit. The photonic circuit may be referred to herein as an optical circuit. The photonic circuit may be any type of photonic circuit, such as a photonic integrated circuit (PIC) and / or an integrated optical circuit. The photonic circuit can comprise one or more elements for transporting (e.g. transmitting) light (e.g. through the first optical layer 304). The photonic circuit may be at least partially deposited in (and / or on) the first optical layer. For example, the photonic circuit may be fabricated on and / or in the first optical layer 304. The light handled by the optical device and / or the optical PCB may have a wavelength of 100nm to 1 mm. For example, the light handled by the optical device and / or the optical PCB may have a wavelength corresponding to that used for optical communication. As such, in some examples, the light handled by the optical device and / or the optical PCB may have a wavelength of 800nm to 1660nm. In some examples, the light handled by the optical device and / or the optical PCB may have a wavelength of 1290 to 1330nm. In some examples, the light handled by the optical device and / or the optical PCB may have a wavelength of 1530 to 1565 nm. As illustrated in Figures 3A to 3C, the optical device comprises a first coupling portion. As also illustrated in Figures 3A to 3C, the first coupling portion is at least partially formed by a first opening 306 in the first substrate layer 302. As illustrated in Figures 3A to 3C, the first opening 306 exposes a first optical connector 308 located above the first opening 306. The first opening 306 exposing the first optical connector 308 can mean that the first opening 306 is configured to provide access to the first optical connector 308. For example, the first opening 306 can be configured to provide access to the first optical connector 308 from below the optical device (e.g. from a space located below the first substrate layer 302). The first optical connector 308 is adapted to optically couple the optical device to an optical PCB (not shown in Figures 3A to 3C). Thus, in some examples, the first opening 306 can be adapted to allow the optical PCB access to the first optical connector 308, which can correspond to the optical input and / or output of the optical device. In some examples, the first opening 306 can be configured to expose the first optical connector 308 by providing access to one or more elements of the first optical connector 308 that are adapted to transmit light from the optical device, and / or receive light from the optical PCB. In some examples, optical coupling means of the first optical connector 308 may only be accessible via the first opening 306. In some examples, the first opening 306 may be adapted to allow the first optical connector 308 to vertically couple to a second optical connector of the optical PCB. It will be understood that the first coupling portion and the first opening 306 may have different shapes and / or sizes. The dimensions of the first coupling portion and / or the first opening 306 may depend on the configuration of the first optical connector 308 and / or the second optical connector, as referred to herein.

[0038] In some examples, the first optical connector 308 may have a first configuration or a second configuration. In the first configuration, the first optical connector 308 may comprise a portion of the first optical layer 304. For example, the first optical connector 308 may form a part of the first optical layer 304. In these examples, the first optical connector 308 may be made of the same material as the first optical layer 304. In examples in which the first optical connector 308 comprises a portion of the first optical layer 304, the first optical layer 304 and the first optical connector 308 may form a monolithic structure. The portion of the first optical layer may comprise one or more first waveguides. At least one first waveguide of the one or more first waveguides may be tapered. In the second configuration of the first optical connector 308, the first optical connector 308 can comprise one or more second waveguides, one or more first lenses, and a first reflector surface. For at least one second waveguide of the one or more second waveguides, the first reflector surface can be adapted to direct (e.g. reflect) light emitted from the at least one second waveguide toward a respective first lens of the one or more first lenses. The respective first lens can be adapted to direct the light through the first opening 306.

[0039] As illustrated in Figures 3A to 3C, the first opening 306 is adapted to accept (e.g. receive) a second coupling portion of the optical PCB. Although not illustrated in Figures 3A to 3C, in some examples, the second coupling portion of the optical PCB can be a protrusion of the optical PCB. In these examples, the first opening 306 may be adapted to receive the protrusion of the optical PCB. In some examples, the first coupling portion can be a female coupling portion, and the second coupling portion can be a (e.g. corresponding) male coupling portion. For example, the first opening 306 of the first coupling portion can be a receptacle that accepts (e.g. receives) and holds the second coupling portion. In some examples, the second coupling portion can be adapted to protrude into the first opening 306.

[0040] In some examples, the optical device may comprise an electrical circuit located above the first substrate layer 302. The first optical connector 308 can be adapted to optically couple the electrical circuit to the optical PCB (e.g. via the photonic circuit referred to herein). In some examples, the first optical layer 304 can be adapted to optically couple the electrical circuit to the optical PCB. For example, the first optical layer 304 can comprise one or more elements (e.g. the photonic circuit referred to herein) adapted to convert an electrical signal from the electrical circuit into an optical signal, and send the optical signal to the first optical connector 308. Similarly, the one or more elements of the first optical layer 304 may be adapted to convert an optical signal received by the first optical connector 308 (e.g. from the optical PCB) into an electrical signal for the electrical circuit. In some examples, the electrical circuit can be an integrated circuit (IC). In some examples, the IC can be an application specific IC (ASIC). In some examples, the electrical circuit may be, and / or may be comprised in, an electrical die.

[0041] In some examples, the optical device can comprise one or more drivers located above the first substrate layer 302. For example, the one or more drivers may be deposited on the first substrate layer 302. Alternatively, or in addition, in some examples, the optical device may comprise one or more transimpedance amplifiers (TIAs) located above the first substrate layer 302. In some examples, the optical device can comprise the optical layer, the electrical circuit, and control (e.g. driving) circuitry . The control circuity can be configured to transmit and / or receive signals to and / or from the optical PCB (e.g. via the first optical connector 308).

[0042] Figures 4A and 4B are schematic illustrations of an optical PCB according to an embodiment. More specifically, Figures 4A and 4B illustrate different perspective views of the optical PCB. Figure 4A illustrates a lateral (side) view of the optical PCB, and Figure 4B illustrates a view of a top portion of the optical PCB.

[0043] As illustrated in Figures 4A and 4B, the optical PCB comprises a second substrate layer 402 and a second optical layer 406. The second substrate layer 402 may be referred to herein as a laminate layer. The second substrate layer 402 may be made of any kind of substrate material. For example, the second substrate layer 402 may be made of fiberglass and / or epoxy. As illustrated in Figures 4A and 4B, the second substrate layer 402 may comprise a (e.g. rigid) board. In some examples, the second substrate layer 402 may be adapted to give the optical PCB a rigid form. The second substrate layer 402 may be understood to be a base layer on which one or more components (e.g. the second optical layer 406) of the optical PCB may be deposited. The second substrate layer 402 may be referred to herein as a bottom layer of the optical PCB.

[0044] As illustrated in Figure 4B, the second optical layer 406 comprises one or more optical channels 408. The one or more optical channels 408 may be referred to herein as one or more optical lines. The one or more optical channels 408 can be configured to transport light (e.g. photons) through the second optical layer 406. For example, the one or more optical channels 408 can be configured to transport optical signals between one or more components (e.g. modules) mounted on the optical PCB. The one or more optical channels 408 may be formed in the second optical layer 406.

[0045] As also illustrated in Figures 4A and 4B, the second optical layer 406 is located above the second substrate layer 402. In some examples, the second optical layer 406 may be coupled (e.g. directly or indirectly) to the second substrate layer 402. The second optical layer 406 may comprise a (e.g. optical) die. Alternatively, or in addition, the second optical layer 406 may comprise semiconductor material, such as silicon. For example, the second optical layer 406 may be at least partially made from semiconductor material. In some examples, the second optical layer 406 may comprise a silicon die.

[0046] As illustrated in Figures 4A and 4B, the optical PCB comprises a second coupling portion. The second coupling portion comprises a second optical connector 404 adapted to optically couple the optical PCB to an optical device (e.g. as described with reference to Figures 3A to 3C). The second coupling portion is adapted to protrude into a first opening 306 of the optical device. As such, in some examples, the second coupling portion may be a protrusion of the optical PCB. That is, the second coupling portion may (e.g. vertically) protrude and / or extend from (e.g. the second substrate layer 402 of) the optical PCB. As mentioned herein, the second coupling portion can be a male coupling portion. For example, the first opening 306 of the first coupling portion can be a receptacle that accepts (e.g. receives) and holds the second coupling portion. In some examples, the second coupling portion can be adapted to protrude into the first opening 306. In some examples, the second coupling portion and the first opening 306 may be adapted to optically couple the first optical connector 308 and the second optical connector 404, while (e.g. simultaneously) allowing a top surface of the second substrate layer 402 to contact a bottom surface of the first substrate layer 302 (e.g. when the second coupling portion is accepted by the first opening 306). Thus, the optical device referred to herein and the optical PCB referred to herein can enable direct connection (e.g. both optically and f nationally) between the optical device and the optical PCB while providing proper alignment.

[0047] In some examples, the second optical connector 404 can have a first configuration or a second configuration. In the first configuration of the second optical connector 404, the second optical connector 404 can comprise a portion of the second optical layer 406. The portion of the second optical layer 406 can comprise one or more third waveguides. At least one third waveguide of the one or more third waveguides can be tapered. In the second configuration of the second optical connector 404, the second optical connector may comprise one or more fourth waveguides, one or more second lenses, and a second reflector surface. For at least one fourth waveguide of the one or more fourth waveguides, the second reflector surface may be adapted to direct light emitted from the at least one fourth waveguide toward a respective second lens of the one or more second lenses. The respective second lens can be adapted to direct the light through the first opening 306 (i.e. of the optical device). Herein, the first configuration of the first optical connector 308 and / or the first configuration of the second optical connector 404 may be referred to herein as an evanescent / adiabatic coupling configuration. The first configuration of the first optical connector 308 and the first configuration of the second optical connector 404 can be compatible configurations. For example, the first configuration of the first optical connector 308 and / or the first configuration of the second optical connector 404 can enable the first optical connector 308 and the second optical connector 404 to be optically coupled (e.g. as described with reference to Figures 9 to 11 ).

[0048] Herein, the second configuration of the first optical connector 308 and / or the second configuration of the second optical connector 404 may be referred to herein as a lensed connector configuration, and / or a lensed coupling configuration. The second configuration of the first optical connector 308 and second first configuration of the second optical connector 404 can be compatible configurations. For example, the second configuration of the first optical connector 308 and / or the second configuration of the second optical connector 404 can enable the first optical connector 308 and the second optical connector 404 to be optically coupled (e.g. as described with reference to Figures 12 and 13).

[0049] Figure 5 is a schematic illustration of an optical device according to an embodiment. More specifically, Figure 5 illustrates a lateral (side) view of the optical device.

[0050] As described herein (e.g. with reference to Figures 3A to 3C), and as illustrated in Figure 5, the optical device comprises a first substrate layer 302. As also illustrated in Figure 5, the optical device comprises a first coupling portion which is at least partially formed by a first opening 306 in the first substrate layer 302. As illustrated in Figure 5, the first opening 306 exposes a first optical connector 308 located above the first opening 306. As also illustrated in Figure 5, in some examples, the optical device can comprise one or more solder elements 502 located below the first substrate layer 302. The one or more solder elements 502 can be coupled to the first substrate layer 302 (e.g. using an adhesive, such as a tacky flux). The one or more solder elements 502 may comprise one or more solder bumps. For example, the one or more solder elements 502 may comprise one or more solder balls. As illustrated in Figure 5, in some examples, the one or more solder elements can be disposed on a bottom surface of the first substrate layer 302. The one or more solder elements can be adapted to mechanically couple the optical device to (e.g. one or more solder pads of) the optical PCB referred to herein (e.g. via reflow soldering).

[0051] As illustrated in Figure 5, in some examples, the optical device can comprise a cover layer 504. The cover layer 504 may be located above the first optical layer as referred to herein. For example, the cover layer 504 may at least partially enclose the first optical layer. In some examples, as illustrated in Figure 5, the cover layer 504 can at least partially enclose the first optical connector 308. Therefore, as illustrated in the example of Figure 5, the first optical connector 308 may only be (e.g. directly and / or optically) accessible via the first opening 306. The cover layer 504 may be adapted to protect the first optical layer and / or the first optical connector 308. The cover layer 504 may be made of metal, plastic, and / or any suitable material for protecting the first optical layer and / or the first optical connector 308. The cover layer 504 may be referred to herein as a mold, a mold layer, and / or a lid. The cover layer may be a top layer of the optical device.

[0052] As described herein, the first optical connector 308 can have a first configuration or a second configuration. In the first configuration, the first optical connector 308 can comprise a portion of the first optical layer, as defined herein. As such, in some examples, the first optical connector 308 illustrated in Figure 5 may be understood to represent a portion of the first optical layer. As illustrated in Figure 5, in some examples, the optical device can comprise an adhesive layer 506 adapted to couple the first optical layer to the first substrate layer 302. The adhesive layer 506 may comprise at least one solder element 508, as illustrated in Figure 5. The at least one (e.g. plurality of) solder element 508 may comprise at least one solder bump, as defined herein. For example, the at least one solder element 508 may comprise at least one flip-chip bump. In some examples, the at least one solder element 508 may comprise (e.g. be made of) fusible metal alloy. In some examples, the at least one solder element 508 may comprise copper. The at least one solder element 508 of the adhesive layer 506 may couple the first optical layer and the first substrate layer 302. As illustrated in Figure 5, in some examples, the adhesive layer 506 can be located between the first optical layer and the first substrate layer 302. The adhesive layer can comprise an adhesive material. For example, the adhesive material may comprise an underfill material, such as an epoxy material. Figure 6 is a schematic illustration of an optical device according to an embodiment. More specifically, Figure 6 illustrates a lateral (side) view of the optical device. Some of the components of the optical device can be as described with reference to Figure 5.

[0053] As illustrated in Figure 6, in some examples, the optical device may comprise a first protective layer 602 located below the first optical connector 308. As also illustrated in Figure 6, the first protective layer 602 may be disposed on a bottom surface of the first optical connector 308. In some examples, the first protective layer 602 may comprise (e.g. be) a film. For example, as illustrated in Figure 6, the first protective layer 602 may coat at least part of the bottom surface of the first optical connector 308. The first protective layer 602 can be made of a transparent material. As such, the first protective layer can be adapted to allow (e.g. optical) light to pass through it.

[0054] Although not illustrated in Figure 6, in some examples, the optical PCB may comprise a second protective layer located above the second optical connector. The second protective layer may be disposed on a top surface of the second optical connector. In some examples, the second protective layer may comprise (e.g. be) a film. For example, the second protective layer may coat at least part of the top surface of the second optical connector. The second protective layer can be made of the transparent material. As such, the second protective layer can be adapted to allow (e.g. optical) light to pass through it.

[0055] In some examples, the transparent material referred to herein can be an adhesive. For example the transparent material can be an optical adhesive, such as an optical glue. As such, in some examples, the first opening, as defined herein, can be protected with optical adhesive (e.g. optical glue). The optical adhesive may be thermally activated. For example, the optical adhesive may be activated during a soldering process (e.g. which can occur during fabrication of the system referred to herein). Optical glue can be understood to refer to a type of glue used in optics for the attachment of fibers. Optical glue beneficially preserves (e.g. correct) refraction index without perturbing light propagation.

[0056] In some examples, the transparent material (e.g. optical glue) may be activated by heat. In some examples, the transparent material may have a melting point greater than or equal to 200°C. For example, the transparent material may have a melting point in the range of 200°C to 300°C. In a specific example, the transparent material may have a melting point equal to 260°C. In some examples, the melting point of the transparent material may be equal to a first temperature value and the melting point of the one or more solder elements 502 of the optical device may be equal to a second temperature value. In these examples, the first temperature value can be less than or equal to the second temperature value. For example, if the second temperature value is 260°C, the first temperature value may be less than or equal to 260°C (e.g. 240°C). In examples in which the first temperature value is less than or equal to the second temperature value, the transparent material (e.g. optical glue) can be said to have a melting point that is less than or equal to the melting point of the one or more solder elements 502. As such, the transparent material (e.g. optical glue) can become soft at (e.g. reflow) soldering temperatures. In this way, the transparent material (e.g. optical glue) can become soft during soldering and adhere to the first optical connector 308 and / or the second optical connector, as defined herein (e.g. during fabrication of the system referred to herein).

[0057] As illustrated in Figure 6, in some examples, the optical device may comprise at least one wall 604. The at least one wall 604 can be disposed between the first optical layer and the first substrate layer 302. As illustrated in Figure 6, the at least one wall 604 can be disposed between the adhesive layer 506 and the first opening. The at least one wall 604 may be impermeable to liquid. As such, the at least one wall can be adapted to prevent material from the adhesive layer 506, such as adhesive and / or solder, from invading the (e.g. space created by the) first opening. In some examples, the at least one wall 604 can comprise at least one solder dam and / or at least one solder mask dam. In examples in which the adhesive layer comprises underfill material, the at least one wall can prevent the underfill from invading the first opening and potentially disturbing the optical coupling between the first optical connector 308 and the second optical connector, as referred to herein. In some examples, the at least one wall 604 can surround an entire edge of the first opening.

[0058] As also illustrated in Figure 6, the optical device may comprise at least one channel 606 comprised in the first substrate layer 302. The at least one channel 606 can comprise at least one gutter. As illustrated in the example of Figure 6, the at least one channel 606 may comprise two channels. However, it will be understood that this is merely an example, and that the at least one channel 606 can comprise other numbers of (e.g. one or more) channels according to other examples. As illustrated in Figure 6, in some examples, the at least one channel 606 may extend from a top surface of the first substrate layer 302. For example, the at least one channel may (e.g. at least partially) extend (e.g. down) through the first substrate layer 302 from the top surface of the first substrate layer 302. The at least one channel 606 can comprise an opening at the top of the channel. The at least one channel 606 may be adapted to capture liquid (e.g. via the opening at the top of the channel). For example, the at least one channel 606 can be adapted to collect excess of adhesive material of the adhesive layer 506. For example, the adhesive material (e.g. glue) may create spill- off (e.g. when heated) which can be collected by the at least one channel 606 (e.g. as the adhesive material flows toward the first opening). Spill-off may occur in an assembly process of the optical device, and / or the assembly process of the system referred to herein. As such, in some examples, the at least one channel 606 can prevent solder (e.g. run off) from invading the space formed by the first opening 306. In some examples, the at least one channel 606 may at least partially surround the first opening. In some examples, the at least one channel 606 may be disposed on, and / or formed at, each edge of the first substrate layer 302 that forms the first opening. In some examples, the at least one channel 606 can be a recess formed in the top surface of the first substrate layer 302. It will be understood that the size and / or location of the at least one channel 606 (e.g. gutter) can vary (e.g. depending on the location of adhesive material in the adhesive layer 506).

[0059] As such, in some examples, the optical device can include structures (e.g. the at least one wall and / or the at least one channel) for accommodating excess of adhesive material (e.g. glue) that can spill out of the adhesive layer 506 during fabrication (e.g. during soldering). The at least one wall and / or the at least one channel can therefore provide protection for the first optical connector 308 and reduce the risk of invading material that can damage the first optical connector 308 and / or impact light propagation.

[0060] Figure 7 is a schematic illustration of a first coupling portion of an optical device, as defined herein. More specifically, Figure 7 illustrates a view of a top surface of the first substrate layer 302 as referred to herein. The first substrate layer 302 of Figure 7 can be as described with reference to Figure 3C above. As illustrated in Figure 7, in some examples, the first opening may be rectangular (e.g. have a rectangular cross-section). However, it will be understood that this is merely an example and that the (e.g. cross- sectional) shape of the first opening 306 may be any shape that is adapted to accept the second coupling portion of the optical PCB, as referred to herein. As described with reference to Figures 5 and 6, in some examples, the optical device can comprise an adhesive layer comprising at least one solder element. The at least one solder element may comprise at least one solder bump, as defined herein. The at least one solder element may be located (e.g. disposed) on a bottom surface of the optical layer as defined herein. As illustrated in Figure 7, in some examples, at least one solder pad 702 can be located above the first substrate layer 302. For example, the at least one solder pad 702 can be disposed on a top surface of the first substrate layer 302. As also illustrated in Figure 7, in some examples, the at least one solder pad 702 may comprise an arrangement of solder pads on the top surface of the first substrate layer 302. The at least one solder pad 702 may be a grid, array, and / or an array grid of solder pads. Although not illustrated in Figure 7, the configuration of the at least one solder element, as defined herein, may correspond to the configuration of the at least one solder pad 702. For example, the at least one solder pad 702 can correspond to at least one site adapted to receive the at least one solder element. As illustrated in Figure 7, in some examples, the at least one solder pad 702 may have a circular shape. However, it will be understood that this is merely an example and that the at least one solder pad 702 may have other shapes (e.g. rectangular) according to other examples.

[0061] As also illustrated in Figure 7, and as described with reference to Figure 6, in some examples, the optical device may comprise at least one wall 604. As illustrated in the example of Figure 7, the at least one wall 604 may comprise three walls. However, it will be understood that this is merely an example, and that the at least one wall 604 can comprise other numbers of (e.g. one or more) walls according to other examples. As illustrated in Figure 7, the at least one wall 604 can be disposed between the at least one solder pad 702 and the first opening 306. For example, the at least one wall 604 can be disposed between the adhesive layer, as defined herein, and the first opening 306. The at least one wall 604 may be impermeable to liquid. As such, the at least one wall can be adapted to prevent material from the adhesive layer 506, such as adhesive and / or solder, from invading the (e.g. space created by the) first opening 306. As illustrated in Figure 7, in some examples, the at least one wall 604 can be adapted to at least partially surround the first opening 306. The at least one wall may be located (e.g. disposed) on the top surface of the first substrate layer 302. For example, the at least one wall may extend from the top surface of the first substrate layer 302. Figure 8 is a schematic illustration of a system according to an embodiment. The system illustrated in the example of Figure 8 comprises an optical device and an optical PCB. The example system illustrated in Figure 8 may be said to be an example of the first optical connector of the optical device being in a first configuration, as defined herein, and / or the second optical connector of the optical PCB being in a first configuration, as defined herein. In the schematic illustration of the system shown in Figure 8, a view of a bottom side of the optical PCB is shown, and a view of a bottom side of the optical device is shown. The schematic illustration of Figure 8 can be understood to illustrate an exploded view of the system. The example system illustrated in Figure 8 may be understood to be an example of the optical PCB and the optical device being in an uncoupled state. The dashed lines in Figure 8 can be understood to represent elements (i.e. of the optical device and the optical PCB) that are located behind the second substrate layer 402 of the optical PCB (i.e. relative to the view shown in Figure 8).

[0062] As illustrated in Figure 8, and as described with reference to Figures 5 and 6, in some examples, the optical device can comprise one or more solder elements 502 located below the first substrate layer 302. The one or more solder elements 502 can be coupled to the first substrate layer 302 (e.g. using an adhesive). As also illustrated in Figure 8, in some examples, the optical PCB can comprise one or more solder pads 802 located above the second substrate layer 402. For example, the one or more solder pads can be disposed, and / or deposited, on a top surface of the second substrate layer 402. As illustrated in Figure 8, the one or more solder elements 502, and / or the one or more solder pads 802, can be adapted to mechanically couple the optical device and the optical PCB (e.g. by reflow soldering). For example, each of the one or more solder elements 502 can be associated with a corresponding solder pad of the one or more solder pads 802. As illustrated in Figure 8, in some examples, the one or more solder elements 502 can comprise four solder bumps, and the one or more solder pads 802 can comprise four square solder pads. However, it will be understood that this is merely an example and that the one or more solder elements 502 can comprise any number of one or more solder elements, and that the one or more solder pads 802 can comprise any (e.g. corresponding) number of one or more solder pads, according to other examples.

[0063] As illustrated in Figure 8, the first opening 306 of the optical device is adapted to accept (e.g. receive) the second coupling portion of the optical PCB. The configuration of the second coupling portion (of the optical PCB) and the first coupling portion (of the optical device), as illustrated in the example system of Figure 8, can be said to be a male-female coupling configuration, as described herein. The configuration of the second coupling portion (of the optical PCB) and the first coupling portion (of the optical device), as illustrated in the example system of Figure 8, can enable correct alignment of the one or more solder elements 502 and the one or more solder pads 802.

[0064] Figure 9 is a schematic illustration of a system according to an embodiment. The system illustrated in the example of Figure 9 comprises an optical device and an optical PCB. The example system illustrated in Figure 9 may be said to be an example of the first optical connector 902 of the optical device being in a first configuration, as defined herein, and the second optical connector 920 of the optical PCB being in a first configuration, as defined herein. In the schematic illustration of the system in Figure 9, a view of a top side of the optical PCB is shown, and a view of a top side of the optical device is shown. As such, the schematic illustration of Figure 9 can be understood to illustrate an exploded view of the system.

[0065] As described with reference to Figures 3A to 3C above, in some examples, the first optical connector 902 referred to herein may have a first configuration or a second configuration. As mentioned above, in the example illustrated in Figure 9, the first optical connector 902 can be said to be in the first configuration. In the first configuration, the first optical connector 902 can comprise a portion 908 of the first optical layer, as defined herein. For example, the first optical connector 902 can form a part of the first optical layer. As illustrated in Figure 9, in some examples, the portion 908 of the first optical layer may comprise one or more first waveguides 904, 906. Although not explicitly illustrated in Figure 9, at least one first waveguide of the one or more first waveguides 904, 906 may be tapered. The one or more first waveguides 904, 906 can be one or more optical waveguides.

[0066] As illustrated in Figure 9, in some examples, the one or more first waveguides 904, 906 may extend along a length of the portion 908 of the first optical layer. In some examples, at least one first waveguide of the one or more first waveguides 904, 906 can have a cross sectional area that decreases along the length of the portion 908 of the first optical layer. In some examples, the one or more first waveguides 904, 906 may have a rectangular cross section. In some examples, the one or more first waveguides 904, 906 may be (e.g. substantially) parallel to each other, as illustrated in Figure 9. In some examples, the one or more first waveguides 904, 906 may comprise an input waveguide 904 and an output waveguide 906. The input waveguide 904 may be configured to receive light from, for example, the second optical connector 920. The output waveguide 906 may be configured to transmit light to, for example, the second optical connector 920. In some examples, the output waveguide 906 may be a tapered waveguide and the input waveguide 904 may be a non-tapered waveguide (e.g. a waveguide with uniform cross-sectional area along its length). As illustrated in Figure 9, in some examples, the optical device can comprise an optical transceiver (TX) 916 coupled to the output waveguide 906. As also illustrated in Figure 9, in some examples, the optical device may comprise an optical receiver (RX) 914 coupled to the input waveguide 904. Thus, in some examples, the optical TX 916 and the optical RX 914 may be connected to the output waveguide 906 and the input waveguide 904, respectively.

[0067] As described with reference to Figures 4A and 4B above, in some examples, the second optical connector 920 referred to herein may have a first configuration or a second configuration. As mentioned above, in the example illustrated in Figure 9, the second optical connector 920 can be said to be in the first configuration. In the first configuration, the second optical connector 920 can comprise a portion 918 of the second optical layer, as defined herein. For example, the second optical connector 920 can form a part of the second optical layer. As illustrated in Figure 9, in some examples, the portion 918 of the second optical layer may comprise one or more third waveguides 910, 912. Although not explicitly illustrated in Figure 9, at least one third waveguide of the one or more third waveguides 910, 912 may be tapered. The one or more third waveguides 910, 912 can be one or more optical waveguides. In some examples, the one or more third waveguides 910, 912 can extend along a length of the portion 918 of the second optical layer. In some examples, at least one third waveguide may have a cross sectional area that decreases along the length of the portion 918 of the second optical layer. In some examples, the one or more third waveguides 910, 912 may have a rectangular cross section.

[0068] In some examples, the one or more third waveguides 910, 912 may comprise an input waveguide 912 and an output waveguide 910. The input waveguide 912 may be configured to receive light from, for example, the first optical connector 902. The output waveguide 910 may be configured to transmit light to, for example, the first optical connector 902. In some examples, the output waveguide 910 may be a tapered waveguide and the input waveguide 912 may be a non-tapered waveguide.

[0069] As illustrated in Figure 9, the first coupling portion of the optical device and the second coupling portion of the optical PCB can be aligned. As such, as also illustrated in Figure 9, the first optical connector 902 and the second optical connector 920 can be superposed. In examples in which the first optical connector 902 is in the first configuration and the second optical connector 920 is in the first configuration, each first waveguide of the one or more first waveguides 904, 906, as defined herein, can be superposed with a respective third waveguide of the one or more third waveguides 910, 912, as defined herein. For example, with reference to the example illustrated in Figure 9, the input waveguide 904 of the first optical connector 902 can be superposed with the output waveguide 910 of the second optical connector 920. In this way, the configuration of the one or more first waveguides 904, 906 and the one or more third waveguides 910, 912 can enable the optical coupling of the first optical connector 902 and the second optical connector 920. As such, in some examples, the optical device and the optical PCB can be optically coupled via the one or more first waveguides 904, 906 and the one or more third waveguides 910, 912 (e.g. when the optical device is mechanically coupled to, and / or mounted on, the optical PCB). The coupling technique provided by the first configuration of the first optical connector and the first configuration of the second optical connector enables the use of single mode waveguides.

[0070] Figure 10 is a schematic illustration of a system according to an embodiment. The system illustrated in the example of Figure 10 can be as described with reference to the system of Figure 9. In the schematic illustration of the system in Figure 10, the optical device and the optical PCB are coupled (e.g. via the first coupling portion, as defined herein, and the second coupling portion, as defined herein). As illustrated in Figure 10, in some examples, the optical device may be mounted on the optical PCB. As such, the schematic illustration of Figure 10 can be understood to illustrate a coupled and / or assembled view of the system referred to herein.

[0071] In examples in which the first optical connector 902 is in the first configuration and the second optical connector 920 is in the first configuration (such as that illustrated in Figure 10), each first waveguide of the one or more first waveguides 904, 906 can be superposed (e.g. aligned) with a respective third waveguide of the one or more third waveguides. In some examples, the one or more first waveguides 904, 906 can be adapted to evanescently couple to the one or more third waveguides. For example, each first waveguide of the one or more first waveguides 904, 906 can (e.g. evanescently) couple to a respective third waveguide of the one or more third waveguides. Similarly, the one or more third waveguides can be adapted to (e.g. evanescently) couple to the one or more first waveguides 904, 906. As such, the first optical connector can be adapted to optically coupled the optical device to the optical PCB via the one or more first waveguides 904, 906, and / or the second optical connector can be adapted to optically couple the optical PCB to the optical device via the one or more third waveguides. Evanescent coupling can be referred to herein as adiabatic coupling.

[0072] In some examples, each first waveguide of the one or more first waveguides 904, 906 may come into contact (e.g. be flush with) a respective third waveguide of the one or more third waveguides when the optical device is mounted on the optical PCB (e.g. as shown in Figure 10). For example, each first waveguide of the one or more first waveguides 904, 906 may be arranged on top of a respective third waveguide of the one or more third waveguides.

[0073] As illustrated in Figures 9 and 10, in the first configuration of the second optical connector 920, the second optical connector 920 can comprise a portion 918 of second optical layer 406. The second optical layer 406 can correspond to a top layer of the optical PCB. For example, the second optical layer 406 can be a topmost layer of a stack of layers of the optical PCB. As illustrated in Figures 9 and 10, the portion 918 of the second optical layer 406 can be adapted (e.g. patterned) to slot (e.g. fit) into the first opening of the optical device, as defined herein.

[0074] As mentioned herein, and as illustrated in Figure 10, the second optical layer comprises one or more optical channels 408. The one or more optical channels 408 can be configured to transmit and / or transport light to and / or from the second optical connector 920. For example, although not illustrated in Figure 10, the one or more optical channels 408 may optically couple the optical device to one or more other modules (e.g. mounted on the optical PCB).

[0075] Figure 11 is a schematic illustration of evanescent coupling. As mentioned herein, evanescent coupling may be referred to as adiabatic coupling. As illustrated in Figure 11 , evanescent coupling can occur between a tapered waveguide and a non-tapered waveguide. Evanescent coupling, as referred to herein, can be understood to be a type of optical coupling.

[0076] Optical coupling may be said to be adiabatic or evanescent if the optical coupling involves a progressive transfer of light. As illustrated in Figure 1 1 , evanescent coupling can occur when a tapered waveguide is in contact with another non-tapered waveguide. In more detail, evanescent coupling can occur as light is transmitted along the tapered waveguide and the light progressively transfers into the other non-tapered waveguide as the cross-sectional area of the tapered waveguide becomes progressively smaller (i.e. as the tapered waveguide becomes narrower).

[0077] The optical coupling illustrated in Figure 11 is an example of the optical coupling that can occur between the one or more first waveguides, as defined herein, and the one or more third waveguides, as defined herein.

[0078] Figure 12 is a schematic illustration of a first optical connector and / or a second optical connector, according to an embodiment. In more detail, the first optical connector of the optical device and / or the second optical connector of the optical PCB may (e.g. both) have the configuration of the optical connector illustrated in Figure 12. In some examples, both the first optical connector and the second optical connector may have the structure illustrated in Figure 12. As such, in some examples, the structure of the first optical connector and the structure of the second optical connector may be the same. For completeness, each of the first optical connector and the second optical connector will now be described with reference to Figure 12.

[0079] As described herein, the first optical connector may have a first configuration or a second configuration. The example illustrated in Figure 12 may be said to illustrate a second configuration of the first optical connector. As illustrated in Figure 12, in some examples, in the second configuration of the first optical connector, the first optical connector can comprise one or more second waveguides 1202. The one or more second waveguides 1202 may be arranged in a parallel configuration, as illustrated in Figure 12. The one or more second waveguides 1202 may be one or more optical waveguides. As also illustrated in Figure 12, in the second configuration of the first optical connector, the first optical connector can comprise one or more first lenses 1204 and a first reflector surface 1206. As illustrated in Figure 12, for at least one second waveguide of the one or more second waveguides, the first reflector surface can be adapted to direct light emitted from the at least one second waveguide toward a respective first lens of the one or more first lenses. Although not illustrated in Figure 12, the respective first lens can be adapted to direct (e.g. focus) the light through the first opening of the optical device.

[0080] As illustrated in the example of Figure 12, the first optical connector can comprise four second waveguides 1202 and four respective first lenses 1204. However, it will be understood that this is merely an example, and that the first optical connector may comprise any number of one or more second waveguides and respective first lenses.

[0081] As illustrated in Figure 12, in some examples, in the second configuration of the first optical connector, the first optical connector may comprise a first housing 1208. As also illustrated in Figure 12, the first housing 1208 can comprise the one or more second waveguides 1202 and the one or more first lenses 1204. For example, the first housing 1208 may be an enclosure. As such, in some examples, the first housing 1208 may enclose the one or more second waveguides 1202 and the one or more first lenses 1204. The first housing 1208 may be a solid housing (e.g. not hollow). For example, the one or more second waveguides 1202 and the one or more first lenses 1204 may be disposed in, formed in, and / or suspended in (e.g. a material of) the first housing 1208. In some examples, the one or more second waveguides 1202 may be formed in the first housing 1208 via an ion-exchange process. In some examples, the first housing 1208 may be made of a (e.g. optically) transparent material, such as glass.

[0082] As illustrated in Figure 12, in some examples, the first reflector surface 1206 can be a surface of the first housing 1208. As also illustrated in Figure 12, in some examples, the first reflector surface 1206 may extend from a top surface of the first housing 1208. As mentioned herein, the first reflector surface 1206 can be adapted to direct light emitted from at least one second waveguide of the one or more second waveguides 1202 toward a respective first lens of the one or more first lenses 1204. In some examples, for each second waveguide of the one or more second waveguides 1202, the angle of incidence between the first reflector surface 1206 and the light emitted from the second waveguide may be 40 to 50 degrees. For example, the angle of incidence can be 45 degrees. The light emitted from the one or more second waveguides 1202 can be emitted from an end of the one or more second waveguides 1202 that faces, and / or is closest to, the first reflector surface 1206. The first reflector surface can be a mirror (e.g. mirrored) surface. For example, the first reflector surface 1206 may be a 45 degree mirror. As illustrated in Figure 12, the one or more first lenses 1204 can be disposed on a bottom surface of the first housing 1208.

[0083] As also illustrated in Figure 12, in some examples, the one or more first lenses 1204 can be an array of lenses. In some examples, the one or more first lenses may be cylindrical. The diameter of each first lens of the one or more first lenses 1204 may be 200-500 micrometers (e.g. to have a tolerance diameter of 100 microns). As illustrated in Figure 12, in some examples, the one or more first lenses 1204 can be comprised in one or more (e.g. cylindrical) holes. The depth of the one or more holes can depend on the desired amount of beam expansion of the light entering the one or more first lenses 1204.

[0084] As described herein, the second optical connector may have a first configuration or a second configuration. The example illustrated in Figure 12 may be said to illustrate a second configuration of the second optical connector. As illustrated in Figure 12, in some examples, in the second configuration of the second optical connector, the second optical connector can comprise one or more fourth waveguides 1202. The one or more fourth waveguides 1202 may be arranged in a parallel configuration, as illustrated in Figure 12. The one or more fourth waveguides 1202 may be one or more optical waveguides. As also illustrated in Figure 12, in the second configuration of the second optical connector, the second optical connector can comprise one or more second lenses 1204 and a second reflector surface 1206. As illustrated in Figure 12, for at least one fourth waveguide of the one or more fourth waveguides, the second reflector surface can be adapted to direct light emitted from the at least one fourth waveguide toward a respective second lens of the one or more second lenses 1204. Although not illustrated in Figure 12, the respective second lens can be adapted to direct the light through the first opening of the optical device, as referred to herein.

[0085] As illustrated in the example of Figure 12, the second optical connector can comprise four fourth waveguides 1202 and four respective second lenses 1204. However, it will be understood that this is merely an example, and that the second optical connector may comprise any number of one or more fourth waveguides and respective second lenses.

[0086] As illustrated in Figure 12, in some examples, in the second configuration of the second optical connector, the second optical connector may comprise a second housing 1208. As also illustrated in Figure 12, the second housing 1208 can comprise the one or more fourth waveguides 1202 and the one or more second lenses 1204. For example, the second housing 1208 may be an enclosure. As such, in some examples, the second housing 1208 may enclose the one or more fourth waveguides 1202 and the one or more second lenses 1204. The second housing 1208 may be a solid housing (e.g. not hollow). For example, the one or more fourth waveguides 1202 and the one or more second lenses 1204 may be disposed in, formed in, and / or suspended in (e.g. a material of) the second housing 1208. In some examples, the one or more fourth waveguides 1202 may be formed in the second housing 1208 via an ion-exchange process. In some examples, the second housing 1208 may be made of a (e.g. optically) transparent material, such as glass.

[0087] As illustrated in Figure 12, in some examples, the second reflector surface 1206 can be a surface of the second housing 1208. As also illustrated in Figure 12, in some examples, the second reflector surface 1206 may extend from a top surface of the second housing 1208. As mentioned herein, the second reflector surface 1206 can be adapted to direct light emitted from at least one fourth waveguide of the one or more fourth waveguides 1202 toward a respective second lens of the one or more second lenses 1204. In some examples, for each fourth waveguide of the one or more fourth waveguides 1202, the angle of incidence between the second reflector surface 1206 and the light emitted from the fourth waveguide may be 40 to 50 degrees. For example, the angle of incidence can be 45 degrees. The light emitted from the one or more fourth waveguides 1202 can be emitted from an end of the one or more fourth waveguides 1202 that faces the second reflector surface 1206. The second reflector surface can be a mirror (e.g. mirrored) surface. For example, the second reflector surface 1206 may be a 45 degree mirror. As illustrated in Figure 12, the one or more second lenses 1204 can be disposed on a bottom surface of the second housing 1208.

[0088] As also illustrated in Figure 12, in some examples, the one or more second lenses 1204 can be an array of lenses. In some examples, the one or more second lenses may be cylindrical. The diameter of each second lens of the one or more second lenses may be 200-500 micrometers (e.g. to have a tolerance diameter of 100 microns). As illustrated in Figure 12, in some examples, the one or more second lenses 1204 can be comprised in one or more (e.g. cylindrical) holes. The depth of the one or more holes can depend on the desired amount of beam expansion of the light entering the one or more second lenses 1204. Figure 13 is a schematic illustration of a system according to an embodiment. In more detail, Figure 13 illustrates a second configuration of a first optical connector 1302 of an optical device and a second configuration of a second optical connector 1304 of an optical PCB. In the example illustrated in Figure 13, the first optical connector 1302 and the second optical connector 1304 may be said to be optically coupled. In the example illustrated in Figure 13, the optical device can be said to be mounted on the optical PCB. The type of optical coupling arising from the second configuration of the first optical connector 1302, as defined herein, and / or the second configuration of the second optical connector 1304, as defined herein, can be said to be vertical (optical coupling).

[0089] The second configuration of the first optical connector 1302 and the second configuration of the second optical connector 1304 is described herein (e.g. with reference to Figure 12 above). As illustrated in Figure 13, light can be emitted from the one or more second waveguides 1306 of the first optical connector 1302. The emitted light can then be reflected by the first reflector surface 1308. As illustrated in Figure 13, the first reflector surface 1308 may be a surface of the first housing 1310, as defined herein. The first reflector surface 1308 may comprise a micro-mirror.

[0090] As illustrated in Figure 13, for at least one second waveguide of the one or more second waveguides 1306, the first reflector surface 1308 can be adapted to direct light 1314 emitted from the at least one second waveguide toward a respective first lens of one or more first lenses 1312, as defined herein. Although not illustrated in Figure 13, the respective first lens can be adapted to direct (e.g. focus) the (emitted) light 1314 through the first opening of the optical device.

[0091] As illustrated in Figure 13, in some examples, the one or more second lenses 1316 can be adapted to direct (e.g. focus) the light from the one or more first lenses 1312 towards the second reflector surface 1324, as defined herein. The second reflector surface 1324 can be adapted to direct the received light 1320 towards the one or more fourth waveguides 1322, as defined herein. As such, the one or more fourth waveguides can be adapted to receive the light from the second reflector surface 1324. As illustrated in Figure 13, the second reflector surface 1324 may be a surface of the second housing 1318, as defined herein. The second reflector surface 1324 can comprise a micro-mirror. The light being transmitted between the first optical connector 1302 and the second optical connector 1304 may undergo a beam expansion upon entering the one or more first lenses 1312 and / or the one or more second lenses 1316. As illustrated in Figure 13, in some examples, the first optical connector 1302 and the second optical connector 1304 can be vertically (optically) coupled. The coupling can be realized using the first and second reflector surfaces (e.g. deflecting mirrors) and the one or more first and second lenses. The coupling realized thought the use of the first optical connector 1302 in the second configuration and the second optical connector 1304 in the second configuration can be referred to herein as a lensed connector configuration (e.g. that operates beam expansion). In the second configuration, the first optical connector 1302 and the second optical connector 1304 may have a smaller size than in the first configuration (e.g. evanescent coupling), as described herein. For example, in the second configuration, the first optical connector 1302 and the second optical connector 1304 may not need to accommodate dimensions to allow for evanescent coupling between optical waveguides.

[0092] The example illustrated in Figure 13 has been described with reference to light being transmitted by the first optical connector 1302 and received by the second optical connector 1304. However, it will be understood that the example illustrated in Figure 13 could equally be used to describe transmission of light by the second optical connector 1304 and receipt of light by the first optical connector 1302.

[0093] Figure 14 is a schematic illustration of a system according to an embodiment. Figure 14 illustrates a first coupling portion of an optical device, as defined herein, and a second coupling portion of an optical PCB, as defined herein. In more detail, Figure 14 illustrates a second configuration of a first optical connector 1302 of an optical device and a second configuration of a second optical connector 1304 of an optical PCB. Figure 14 may be said to be an exploded view of the system comprising the first optical connector 1302 and the second optical connector 1304. The first optical connector 1302 and the second optical connector 1304 of Figure 14 can be as described with reference to Figures 12 and 13.

[0094] As described herein, and as illustrated in Figure 14, the first coupling portion is at least partially formed by a first opening 306 in a first substrate layer 302 of the optical device. As also illustrated in Figure 14, the first opening 306 exposes the first optical connector 1302 located above the first opening 306. The first opening is adapted to accept (e.g. receive) a second coupling portion (e.g. the second optical connector 1304) of the optical PCB. For example, as illustrated in Figure 14, the second optical connector 1304 can be adapted to slot into the first opening 306 (e.g. when the optical device is mounted on the optical PCB). Similarly, the second coupling portion (e.g. the second optical connector 1304) is adapted to protrude into the first opening 306.

[0095] As illustrated in Figure 14, in some examples, when the first optical connector 1302 is in the second configuration, the first optical connector 1302 can be coupled (e.g. mechanicaly and / or optically) to the first optical layer 304 (e.g. optical die). As also illustrated in Figure 14, in some examples, when the second optical connector 1304 is in the second configuration, the second optical connector 1304 can be coupled (e.g. mechanicaly and / or optically) to the second optical layer 406 (e.g. optical die).

[0096] Figures 15 to 17 are schematic illustrations of a system according to some embodiments. Figures 15 to 17 illustrate different perspective views of the system.

[0097] As illustrated in Figures 15 to 17, the optical PCB comprises a second optical layer 406 located above a second substrate layer of the optical PCB, as defined herein. The second optical layer 406 can be deposited and / or fabricated on the second substrate layer. As illustrated in Figures 15 and 16, the second optical layer 406 comprises one or more optical channels 408. As illustrated in Figures 15 and 16, the one or more optical channels can be configured to optically couple one or more modules and / or one or more components (e.g. including the optical device referred to herein) mounted on the optical PCB. The one or more modules can comprise one or more optical packages, such as one or more CPO modules. For example as illustrated in Figures 15 to 17, in some examples, the optical PCB can comprise one or more circuits 1502, 1504, 1506. The second optical layer 406 can be adapted to optically couple the one or more circuits 1502, 1504, 1506 to the optical device. In some examples, the one or more channels 408 can be adapted to optically couple the one or more circuits 1502, 1504, 1506 to the second optical connector of the optical PCB. In some examples, the second optical connector can be adapted to optically couple the one or more circuits 1502, 1504, 1506 to the optical device. The patterning of the second optical layer 406 and / or the one or more channels can vary depending on the structure (e.g. design) of the optical PCB.

[0098] As illustrated in Figures 16 and 17, in some examples, the optical device may comprise an (e.g. one or more) electrical circuit located above the first substrate layer, as defined herein. As illustrated in Figures 16 and 17, the first optical connector can be adapted to optically couple the electrical circuit to the optical PCB. Although not explicitly illustrated in Figures 16 and 17, the first optical layer 304 can be adapted to optically couple the electrical circuit to the first optical connector. As such, the first optical layer 304 can be adapted to optically couple the electrical circuit to the optical PCB.

[0099] As also illustrated in Figures 16 and 17, in some examples, the optical device can comprise one or more drivers located above the first substrate layer, and / or one or more transimpedance amplifiers, TIAs, located above the first substrate layer. The one or more drivers and / or the one or more TIAs may be comprised in the first optical layer 304 according to some examples.

[0100] As illustrated in Figures 15 to 17, the first optical layer 304 comprises a photonic circuit. In some examples, the photonic circuit can comprise one or more elements for transporting light

[0101] Figure 18 is a block diagram illustrating a method of fabricating an optical device, as defined herein, according to an embodiment. The optical device can be the optical device as described herein (e.g. with reference to Figures 3A to 3C). As illustrated at block 1802 of Figure 18, the method comprises fabricating the optical device.

[0102] Although not illustrated in Figure 18, in some examples, the method may comprise fabricating the first substrate layer, as defined herein, fabricating the first optical layer, as defined herein, and fabricating the first coupling portion, as defined herein. In some examples, the method may comprise depositing the first optical layer on the first substrate layer. In some examples, fabricating the first substrate layer may comprise creating the first opening of the first substrate layer. Creating the first opening may comprise removing (e.g. cutting) a section of the first substrate layer to form the first opening.

[0103] In some examples, depositing the first optical layer on the first substrate layer may comprise coupling the first optical layer to the first substrate layer. Coupling the first optical layer to the first substrate layer may comprise (e.g. reflow) soldering the first optical layer to the first substrate layer, for example, via the at least one solder element of the adhesive layer, as referred to herein.

[0104] Figure 19 is a block diagram illustrating a method of fabricating an optical PCB, as defined herein, according to an embodiment. The optical PCB can be the optical PCB as described herein (e.g. with reference to Figures 4A and 4B). As illustrated at block 1902 of Figure 19, the method comprises fabricating the optical PCB.

[0105] Although not illustrated in Figure 19, in some examples, the method may comprise fabricating the second substrate layer, as defined herein, fabricating the second optical layer, as defined herein, and fabricating the second coupling portion, as defined herein. In some examples, the method may comprise depositing the second optical layer on the second substrate layer. In some examples, fabricating the second optical layer may comprise patterning the second optical layer.

[0106] In some examples, depositing the second optical layer on the second substrate layer may comprise coupling the second optical layer to the second substrate layer. Coupling the first optical layer to the first substrate layer may comprise coupling the second optical layer to the second substrate layer using an adhesive.

[0107] Figure 20 is a block diagram illustrating a method of fabricating a system, as defined herein, according to an embodiment. The system can be the system as described herein. The system described herein can be referred to as an assembly, and / or a PCB assembly.

[0108] As illustrated at block 2002 of Figure 20, the method comprises obtaining an optical device as defined herein. Obtaining the optical device may comprise fabricating the optical device (e.g. as described with reference to Figure 18). As illustrated at block 2004 of Figure 20, the method comprises obtaining an optical PCB, as defined herein. Obtaining the optical PCB may comprise fabricating the optical PCB (e.g. as described with reference to Figure 19). As illustrated by block 2006 of Figure 20, the method comprises depositing the optical device on the optical PCB. In some examples, the optical device may be deposited on the optical PCB using a flip-chip method.

[0109] Although not illustrated in Figure 20, in some examples, depositing the optical device on the optical PCB may comprise depositing the optical device on the optical PCB using soldering, such as reflow soldering. In some examples, depositing the optical device on the optical PCB using reflow soldering can comprise heating one or more solder elements of the optical device, as defined herein, to a temperature of greater than or equal to 200°C. In some examples, depositing the optical device on the optical PCB may comprise depositing the optical device on the optical PCB using surface mount technology (SMT).

[0110] As described herein, there is provided a system. The system comprises an optical device and an optical PCB. The optical device can be as described herein. The optical PCB can be as described herein.

[0111] Therefore, as described herein, there is provided improved techniques for an optical device, an optical PCB, an assembly comprising the optical device and the optical PCB, and methods of fabrication of the optical device, the optical PCB, and the assembly. The techniques are improved since they address many pain points associated with the assembly of optical devices on optical PCBs. In particular, the techniques increase the viability of optical PCBs as they provide an optical coupling configuration (e.g. of the optical device) such that the optical input and output of the coupling configuration is compatible with the optical PCB assembly procedures. That is, the configuration of the first coupling portion, as defined herein, and / or the second coupling portion, as defined herein, enables correct alignment of the optical connectors of the optical device and the optical PCB.

[0112] Moreover, the first coupling portion and / or the second coupling portion are configured to allow a first opening of the optical device to receive a second optical connector of the optical PCB. In this way, the techniques described herein provide for proper physical alignment of the optical device and optical PCB. For example, solder elements of the optical device can easily be aligned with solder pads on the optical PCB as a result of the configurations of the first and second coupling portions. Thus, the configuration of the optical device and the optical PCB allows for the optical device to be mounted on the optical PCB with standard techniques, such as by using surface mount technology (SMT), while also obtaining correct optical alignment.

[0113] Moreover, the first optical layer (e.g. optical die) of the optical device is not limited to multi-mode operation. The optical device is also not limited to specific types of photonic and / or electric components. In this way, the optical device is compatible with a range of circuity components and can include photonic building blocks that exist in integrated silicon photonics. Some of the techniques described herein do not necessitate the use of vertically emitting sources, as the evanescent / adiabatic coupling configuration, as described herein (e.g. with reference to Figure 9), and the lensed coupling configuration, as described herein (e.g. with reference to Figure 12), can support a horizontal waveguide. Indeed, the techniques described herein enable optical alignment while avoiding the compromise of using multi-mode waveguides and / or a VCSEL (e.g. as a laser light source). As such, the techniques can enable the use of optical wavelengths that are the commonly used in telecommunications, such as 1290-1330nm and / or 1530-1565nm. Additionally, by removing the constraint of using direct modulation, it is possible to use remote laser sources. These laser sources can act as a light source (e.g. feeding optical modulators in the optical device), and thus the optical device described herein, and / or the optical PCB described herein can operate in harsh thermal environments.

[0114] Furthermore, some of the techniques described herein provide for a packaging (e.g. design) and assembly method that provides for protection of optics without complex cleaning procedures. As described herein, in some examples, the first optical connector and / or the second optical connector can be formed with an optical glue which advantageously seals and protects the optical port between the optical device and the optical PCB.

[0115] It should be noted that the above-mentioned embodiments illustrate rather than limit the idea, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. The word “comprising” does not exclude the presence of elements or steps other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims. Any reference signs in the claims shall not be construed so as to limit their scope.

Claims

34CLAIMS1 . An optical device comprising: a first substrate layer (302); a first optical layer (304) comprising a photonic circuit, wherein the first optical layer (304) is located above the first substrate layer (302); and a first coupling portion, wherein the first coupling portion is at least partially formed by a first opening (306) in the first substrate layer (302), the first opening (306) exposing a first optical connector (308) located above the first opening (306), wherein the first optical connector (308) is adapted to optically couple the optical device to an optical printed circuit board, PCB, wherein the first opening (306) is adapted to accept a second coupling portion of the optical PCB.

2. The optical device as claimed in claim 1 , wherein the first optical connector (308) has a first configuration or a second configuration, and wherein: in the first configuration, the first optical connector (308) comprises a portion of the first optical layer (304), wherein the portion of the first optical layer (304) comprises one or more first waveguides (904, 906), and wherein at least one first waveguide of the one or more first waveguides (904, 906) is tapered; and in the second configuration, the first optical connector (308) comprises one or more second waveguides (1202), one or more first lenses (1204), and a first reflector surface (1206), wherein, for at least one second waveguide of the one or more second waveguides (1202), the first reflector surface (1206) is adapted to direct light emitted from the at least one second waveguide toward a respective first lens of the one or more first lenses (1204), and wherein the respective first lens is adapted to direct the light through the first opening (306).

3. The optical device as claimed in claim 2, wherein: the one or more first waveguides (904, 906) are one or more optical waveguides; and / or the one or more second waveguides (1202) are one or more optical waveguides.

4. The optical device as claimed in claim 2 or 3, wherein: the one or more first waveguides (904, 906) extend along a length of the portion of the first optical layer (304).

355. The optical device as claimed in claim 4, wherein at least one first waveguide of the one or more first waveguides (904, 906) has a cross sectional area that decreases along the length of the portion of the first optical layer (304).

6. The optical device as claimed in claim 5, wherein the one or more first waveguides (904, 906) are adapted to evanescently couple to one or more respective third waveguides of the second coupling portion of the optical PCB.

7. The optical device as claimed in any of claims 2 to 6, wherein the one or more first waveguides (904, 906) have a rectangular cross section.

8. The optical device as claimed in any of claims 2 to 7, wherein the one or more first waveguides (904, 906) comprise an input waveguide and an output waveguide.

9. The optical device as claimed in claim 8, comprising: an optical transceiver coupled to the output waveguide; and / or an optical receiver coupled to the input waveguide.

10. The optical device as claimed in any of claims 2 to 9, wherein: in the second configuration, the first optical connector (308) comprises a first housing (1208), wherein the first housing (1208) comprises the one or more second waveguides (1202) and the one or more first lenses (1204), and wherein the first reflector surface (1206) is a surface of the first housing (1208).11 . The optical device as claimed in claim 10, wherein the first reflector surface (1206) extends from a top surface of the first housing (1208).

12. The optical device as claimed in any of claims 2 to 11 , wherein, for each second waveguide of the one or more second waveguides (1202), the angle of incidence between the first reflector surface (1206) and the light emitted from the second waveguide is equal to 45 degrees.

13. The optical device as claimed in any of claims 10 to 12, wherein the one or more first lenses (1204) are disposed on a bottom surface of the first housing (1208).

14. The optical device as claimed in any of claims 10 to 13, wherein the first housing (1208) is made of a transparent material.

15. The optical device as claimed in claim 14, wherein the first housing (1208) is made of glass.

16. The optical device as claimed in any of claims 2 to 15, wherein the first reflector surface (1206) is a mirror surface.

17. The optical device as claimed in any of claims 2 to 16, wherein: in the second configuration, the first optical connector (308) is coupled to the first optical layer (304).

18. The optical device as claimed in any of the preceding claims, wherein the first optical layer (304) comprises an optical die.

19. The optical device as claimed in any of the preceding claims, wherein the first optical layer (304) comprises semiconductor material.

20. The optical device as claimed in claim 19, wherein the semiconductor material is silicon.21 . The optical device as claimed in any of the preceding claims, wherein the photonic circuit comprises one or more elements for transporting light.

22. The optical device as claimed in claim 21 , wherein the light has a wavelength of 800 to 1660nm.

23. The optical device as claimed in claim 22, wherein the light has a wavelength of: 1290 to 1330nm; or1530 to 1565 nm.

24. The optical device as claimed in any of the preceding claims, wherein the first coupling portion is adapted to mechanically couple the optical device to the optical PCB.

25. The optical device as claimed in any of the preceding claims, wherein the second coupling portion of the optical PCB is a protrusion of the optical PCB.

26. The optical device as claimed in any of the preceding claims, wherein the first coupling portion is a female coupling portion, and wherein the second coupling portion is a male coupling portion.

27. The optical device as claimed in any of the preceding claims, wherein one or more edges of the first opening (306) are adapted to at least partially surround the second coupling portion.

28. The optical device as claimed in any of the preceding claims, comprising: one or more solder elements (502) located below the first substrate layer (302).

29. The optical device as claimed in claim 28, wherein the one or more solder elements (502) comprises one or more solder bumps.

30. The optical device as claimed in claim 28 or 29, wherein the one or more solder elements (502) are disposed on a bottom surface of the first substrate layer (302).31 . The optical device as claimed in any of the preceding claims, comprising: a first protective layer (602) located below the first optical connector (308).

32. The optical device as claimed in claim 31 , wherein the first protective layer (602) is disposed on a bottom surface of the first optical connector (308).

33. The optical device as claimed in claim 31 or 32, wherein the first protective layer (602) comprises a film.

34. The optical device as claimed in any of claims 31 to 33, wherein the first protective layer (602) is made of a transparent material.

35. The optical device as claimed in claim 34, wherein the transparent material has a melting point greater than or equal to 200°C.

36. The optical device as claimed in claim 35, wherein the transparent material has a melting point in the range of 200°C to 300°C.3837. The optical device as claimed in claim 34, when directly or indirectly dependent on claim 28, wherein: the melting point of the transparent material is equal to a first temperature value, the melting point of the one or more solder elements (502) is equal to a second temperature value, and the first temperature value is less than or equal to the second temperature value.

38. The optical device as claimed in any of claims 34 to 37, wherein the transparent material is an adhesive.

39. The optical device as claimed in 38 wherein the transparent material is an optical adhesive.

40. The optical device as claimed in any of the preceding claims, comprising: an adhesive layer adapted to couple the first optical layer (304) to the first substrate layer (302).41 . The optical device as claimed in claim 40, wherein the adhesive layer is located between the first optical layer (304) and the first substrate layer (302).

42. The optical device as claimed in claim 40 or 41 , wherein the adhesive layer comprises an adhesive material.

43. The optical device as claimed in any of claims 40 to 42, comprising: at least one wall (604), wherein the at least one wall (604) is disposed between the first optical layer (304) and the first substrate layer (302), and wherein the at least one wall (604) is disposed between the adhesive layer and the first opening (306).

44. The optical device as claimed in any of the preceding claims, comprising: at least one channel (606) comprised in the first substrate layer (302), wherein the at least one channel (606) extends from a top surface of the first substrate layer (302), and wherein the at least one channel (606) comprises an opening at the top of the channel.3945. The optical device as claimed in claim 44, wherein the at least one channel (606) comprises at least one gutter.

46. The optical device as claimed in claim 44 or 45, wherein the at least one channel (606) at least partially surrounds the first opening (306).

47. The optical device as claimed in any of the preceding claims, comprising: a cover layer (504) located above the first optical layer (304), wherein the cover layer (504) at least partially encloses the first optical layer (304).

48. The optical device as claimed in any of the preceding claims, comprising: an electrical circuit located above the first substrate layer (302), wherein the first optical connector (308) is adapted to optically couple the electrical circuit to the optical PCB.

49. The optical device as claimed in claim 48, wherein the first optical layer (304) is adapted to optically couple the electrical circuit to the optical PCB.

50. The optical device as claimed claim 48 or 49, wherein the electrical circuit is an integrated circuit, IC.51 . The optical device as claimed in claim 50, wherein the IC is an application specific IC, ASIC.

52. The optical device as claimed in any of the preceding claims, comprising: one or more drivers located above the first substrate layer (302); and / or one or more transimpedance amplifiers, TIAs, located above the first substrate layer (302).

53. The optical device as claimed in any of the preceding claims, wherein the photonic circuit is a photonic integrated circuit.

54. The optical device as claimed in any of the preceding claims, wherein the optical device is an optical package.

55. An optical printed circuit board, PCB, comprising:40 a second substrate layer (402); a second optical layer (406) comprising one or more optical channels (408), wherein the second optical layer (406) is located above the second substrate layer (402); and a second coupling portion, wherein the second coupling portion comprises a second optical connector (404) adapted to optically couple the optical PCB to an optical device, wherein the second coupling portion is adapted to protrude into a first opening of the optical device.

56. The optical PCB as claimed in claim 55, wherein the second optical connector (404) has a first configuration or a second configuration, and wherein: in the first configuration, the second optical connector (404) comprises a portion of the second optical layer (406), wherein the portion of the second optical layer (406) comprises one or more third waveguides (910, 912), and wherein at least one third waveguide of the one or more third waveguides (910, 912) is tapered; and in the second configuration, the second optical connector (404) comprises one or more fourth waveguides (1202), one or more second lenses (1204), and a second reflector surface (1206), wherein, for at least one fourth waveguide of the one or more fourth waveguides (1202), the second reflector surface (1206) is adapted to direct light emitted from the at least one fourth waveguide toward a respective second lens of the one or more second lenses (1204), and wherein the respective second lens is adapted to direct the light through the first opening (306).

57. The optical PCB as claimed in claim 56, wherein: the one or more third waveguides (910, 912) are one or more optical waveguides; and / or the one or more fourth waveguides (1202) are one or more optical waveguides.

58. The optical PCB as claimed in claim 56 or 57, wherein: the one or more third waveguides (910, 912) extend along a length of the portion of the second optical layer (406).

59. The optical PCB as claimed in claim 58, wherein the at least one third waveguide of the one or more third waveguides (910, 912) has a cross sectional area that decreases along the length of the portion of the second optical layer (406).4160. The optical PCB as claimed in claim 59, wherein the one or more third waveguides (910, 912) are adapted to evanescently couple to one or more respective first waveguides of a first coupling portion of the optical device.61 . The optical PCB as claimed in any of claims 56 to 60, wherein the one or more third waveguides (910, 912) have a rectangular cross section.

62. The optical PCB as claimed in any of claims 56 to 61 , wherein the one or more third waveguides (910, 912) comprise an input waveguide and an output waveguide.

63. The optical PCB as claimed in any of claims 56 to 62, wherein: in the second configuration, the second optical connector (404) comprises a second housing (1208), wherein the second housing (1208) comprises the one or more fourth waveguides (1202) and the one or more second lenses (1204), and wherein the second reflector surface (1206) is a surface of the second housing (1208).

64. The optical PCB as claimed in claim 63, wherein the second reflector surface (1206) extends from a top surface of the second housing (1208).

65. The optical PCB as claimed in any of claims 56 to 64, wherein, for the at least one fourth waveguide of the one or more fourth waveguides (1202), the angle of incidence between the second reflector surface (1206) and the light emitted from the at least one fourth waveguide is equal to 45 degrees.

66. The optical PCB as claimed in any of claims 63 to 65, wherein the one or more second lenses (1204) are disposed on a bottom surface of the second housing (1208).

67. The optical PCB as claimed in any of claims 63 to 66, wherein the second housing (1208) is made of a transparent material.

68. The optical PCB as claimed in claim 67, wherein the second housing (1208) is made of glass.

69. The optical PCB as claimed any of claims 56 to 68, wherein the second reflector surface (1206) is a mirror surface.4270. The optical PCB as claimed in any of claims 56 to 69, wherein: in the second configuration, the second optical connector (404) is coupled to the second optical layer (406).71 . The optical PCB as claimed in any of claims 55 to 70, wherein the second optical layer (406) comprises semiconductor material.

72. The optical PCB as claimed in claim 71 , wherein the semiconductor material is silicon.

73. The optical PCB as claimed in any of claims 55 to 72, wherein the second coupling portion is adapted to mechanically couple the optical PCB to the optical device.

74. The optical PCB as claimed in any of claims 55 to 73, wherein the second coupling portion of the optical PCB is a protrusion of the optical PCB.

75. The optical PCB as claimed in claim 73, wherein the second coupling portion protrudes from the second substrate layer (402).

76. The optical PCB as claimed in any of claims 55 to 75, wherein the first coupling portion is a female coupling portion, and wherein the second coupling portion is a male coupling portion.

77. The optical PCB as claimed in any of claims 55 to 76, wherein the second coupling portion is adapted to protrude into the first opening (306).

78. The optical PCB as claimed in any of claims 55 to 77, comprising: one or more solder pads (802) located above the second substrate layer (402).

79. The optical PCB as claimed in claim 78, wherein the one or more solder pads (802) are disposed on a top surface of the second substrate layer (402).

80. The optical PCB as claimed in any of claims 55 to 79, comprising: a second protective layer located above the second optical connector (404).4381 . The optical PCB as claimed in claim 80, wherein the second protective layer is disposed on a top surface of the second optical connector (404).

82. The optical PCB as claimed in claim 80 or 81 , wherein the second protective layer comprises a film.

83. The optical PCB as claimed in any of claims 80 to 82, wherein the second protective layer is made of a transparent material.

84. The optical PCB as claimed in claim 83, wherein the transparent material has a melting point greater than or equal to 200°C.

85. The optical PCB as claimed in claim 84, wherein the transparent material has a melting point in the range of 200°C to 300°C.

86. The optical PCB as claimed in any of claims 83 to 85, wherein the transparent material is an adhesive.

87. The optical PCB as claimed in 86, wherein the transparent material is an optical adhesive.

88. The optical device as claimed in any of claims 55 to 87, comprising: one or more circuits (1502, 1504, 1506), wherein the one or more optical channels (408) are adapted to optically couple the one or more circuits (1502, 1504, 1506) to the second optical connector (404).

89. The optical device as claimed in claim 88, wherein the second optical connector (404) is adapted to optically couple the one or more circuits (1502, 1504, 1506) to the optical device.

90. The optical PCB as claimed in claim 88 or 89, wherein the second optical layer (406) is adapted to optically couple the one or more circuits (1502, 1504, 1506) to the optical device.91 . A system, comprising: an optical device as claimed in any of claims 1 to 54; and44 an optical printed circuit board, PCB.

92. The system as claimed in claim 94, wherein the optical PCB comprises the optical PCB as claimed in any of claims 54 to 90.

93. A method of fabricating (1802) an optical device, the optical device comprising: a first substrate layer; a first optical layer comprising a photonic circuit, wherein the first optical layer is located above the first substrate layer; and a first coupling portion, wherein the first coupling portion is at least partially formed by a first opening in the first substrate layer, the first opening exposing a first optical connector adapted to optically couple the optical device to an optical printed circuit board, PCB, wherein the first opening is adapted to at least partially surround a second coupling portion of the optical PCB.

94. The method as claimed in claim 93, comprising one or more of: fabricating the first substrate layer; fabricating the first optical layer; and fabricating the first coupling portion.

95. The method as claimed in claim 93 or 94, comprising: depositing the first optical layer on the first substrate layer.

96. A method of fabricating (1902) an optical printed circuit board, PCB, the optical PCB comprising: a second substrate layer; a second optical layer comprising one or more optical channels, wherein the second optical layer is located above the second substrate layer; and a second coupling portion, wherein the second coupling portion comprises a second optical connector adapted to optically couple the optical PCB to an optical device, wherein the second coupling portion is adapted to be at least partially surrounded by a first opening (306) of the optical device.

97. The method as claimed in claim 96, comprising one or more of: fabricating the second substrate layer; fabricating the second optical layer; and45 fabricating the second coupling portion.

98. The method as claimed in claim 96 or 97, comprising: depositing the second optical layer on the second substrate layer.

99. A method of fabricating a system, the method comprising: obtaining (2002) an optical device as claimed in any of claims 1 to 54; obtaining (2004) an optical printed circuit board, PCB, as claimed in any of claims 55 to 90; and depositing (2006) the optical device on the optical PCB.

100. The method as claimed in claim 99, wherein depositing the optical device on the optical PCB comprises depositing the optical device on the optical PCB using reflow soldering.

101. The method as claimed in claim 100, wherein depositing the optical device on the optical PCB using reflow soldering comprises heating one or more solder elements of the optical device to a temperature of greater than or equal to 200°C.

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