DENSE PHOTONIC INTEGRATED CIRCUIT OPTICAL EDGE COUPLING

An optical interconnect component for use in transmitting light between a photonic integrated circuit and one or more optical fibres attached to an optical fibre connector ferrule is disclosed. The optical interconnect component comprises a step formed at an edge of the optical interconnect component, the step including a ledge and a facet, one or more optical beam management elements formed in a surface of the optical interconnect component, and a plurality of integrated optical waveguides. Each of two or more of the integrated optical waveguides extends from the facet so as to define a plurality of optical ports at the facet, and each of the one or more optical beam management elements is aligned with, but separated from, an end of a corresponding one of the plurality of integrated optical waveguides. Also disclosed are an optical fibre connector ferrule, an optical interconnect assembly comprising the optical interconnect component and the optical fibre connector ferrule, and an optical system comprising the optical interconnect assembly, a photonic integrated circuit, and one or more optical fibres.

FIELD

The present disclosure relates to components and assemblies for assisting in high density optical edge coupling to and/or from photonic integrated circuits (PICs) such as Silicon Photonic (SiPh) devices.

BACKGROUND

A significant requirement exists for high channel count optical input/output (I/O) ports in silicon photonic integrated circuit (PIC) applications. This is compounded by the need for tight integration between electronics and photonics in Co-packaged Optics applications (CPO), where transitioning from electronic I/O to photonic I/O can offer significant advantages and high bandwidth scalability.

Achieving high channel counts using conventional optical fiber attach processes can use an undesirable amount of space on the silicon chip which has significant cost and practicality implications.

Conventional optical fiber arrays can achieve channel pitches of the order of the 100 μm, limited by the diameter of the optical fibers used in such arrays. Common pitches are 250 μm or 127 μm, however smaller pitches are also available by using smaller diameter optical fibers such as those with an 80 μm diameter. However using one dimensional arrays of such optical fibers in conventional V-groove arrays places significant limitations on the channel densities achievable.

Optical I/O couplers on PICs can be manufactured with significantly smaller pitch between adjacent couplers such as 25 μm, and can therefore offer substantial increases in channel density. However optical interposer devices are then required to provide optical coupling between these structures and the optical fibers used to carry the signals to the receivers.

Edge-coupled optical interposer devices are commonly used on Silicon Photonic platforms to provide broad spectral bandwidth and low loss coupling to silicon photonic waveguides. However due to the edge geometry, known edge-coupled optical interposer devices are limited to 1D arrays such that reducing the channel-to-channel pitch is the only route available to increase I/O density.

Alternatively, optical interposer devices may be used which employ grating couplers to vertically couple light in and out of the silicon photonics platform. Grating couplers may allow for 2D arrays of couplers to provide more efficient use of die real-estate for 1/O. However, grating couplers typically have higher losses and polarisation sensitivity than edge couplers.

SUMMARY

It should be understood that any one or more of the features of any one of the following aspects of the present disclosure may be combined with any one or more of the features of any of the other foregoing aspects of the present disclosure.

According to an aspect of the present disclosure there is provided an optical interconnect component for use in transmitting light between a photonic integrated circuit and one or more optical fibres attached to an optical fibre connector ferrule, the optical interconnect component comprising:a step formed at an edge of the optical interconnect component, the step including a ledge and a facet;one or more optical beam management elements formed in a surface of the optical interconnect component; anda plurality of integrated optical waveguides,wherein each of two or more of the integrated optical waveguides extends from the facet so as to define a plurality of optical ports at the facet, andwherein each of the one or more optical beam management elements is aligned with, but separated from, an end of a corresponding one of the plurality of integrated optical waveguides.

Such an optical interconnect component may be used to transmit light between a plurality of integrated optical waveguides of the photonic integrated circuit and one or more optical fibres attached to the optical fibre connector ferrule. Such an optical interconnect component may be used for dense edge coupling between optical fibers and optical I/O ports on a photonic integrated circuit such as a silicon photonic integrated circuit.

Optionally, the optical interconnect component comprises, or is formed in, a monolithic block of material such as glass, for example a monolithic block of fused silica.

Optionally, the step is formed in the monolithic block of material.

Optionally, the one or more optical beam management elements are formed in the monolithic block of material.

Optionally, the plurality of integrated optical waveguides are formed in the monolithic block of material.

Optionally, the photonic integrated circuit comprises a plurality of integrated optical waveguides and a step formed at an edge of the photonic integrated circuit, wherein the step includes a ledge and a facet, and wherein each integrated optical waveguide of the photonic integrated circuit ends at the facet of the photonic integrated circuit so as to define a corresponding optical port at the facet of the photonic integrated circuit.

Optionally, the plurality of optical ports at the facet of the optical interconnect component has a spatial configuration which matches a spatial configuration of the plurality of optical ports at the facet of the photonic integrated circuit.

In use, the facet of the optical interconnect component is configured to engage the facet of the photonic integrated circuit so that the optical ports at the facet of the optical interconnect component are aligned with the plurality of optical ports at the facet of the photonic integrated circuit for the transmission of light between the plurality of optical ports of the photonic integrated circuit and the plurality of optical ports of the optical interconnect component.

Optionally, the optical fibre connector ferrule comprises:one or more optical beam management elements, each optical beam management element configured for alignment with a corresponding optical beam management element of the optical interconnect component; andone or more optical fibre alignment structures,wherein each optical fibre alignment structure is configured for engagement with a corresponding optical fibre so that an end of the corresponding optical fibre is aligned with, but separated from, a corresponding one of the optical beam management elements of the optical fibre connector ferrule.

Optionally, wherein the one or more optical beam management elements of the optical interconnect component have a spatial configuration which matches a spatial configuration of the one or more optical beam management elements of the optical fibre connector ferrule.

Optionally, the optical fibre connector ferrule is configured for alignment with the optical interconnect component so as to align each optical beam management element of the optical fibre connector ferrule with a corresponding optical beam management element of the optical interconnect component for the transmission of light between each optical beam management element of the optical interconnect component and a corresponding optical beam management element of the optical fibre connector ferrule.

In use, the one or more optical beam management elements of the optical interconnect component and the one or more optical beam management elements of the optical fibre connector ferrule expand one or more optical beams travelling between the optical interconnect component and the optical fibre connector ferrule thereby relaxing the alignment tolerance required between the optical interconnect component and the optical fibre connector ferrule for a given optical coupling efficiency. This has the potential to simplify optical I/O assembly and packaging for photonic integrated circuits (PICs) such as Silicon Photonic (SiPh) devices.

Optionally, one or more of the optical beam management elements comprise an optical beam collimating element or an optical beam focussing element.

Optionally, one or more of the optical beam management elements comprise a microlens.

Optionally, one or more of the optical beam management elements comprise a waveguide structure such as a segmented waveguide, or a tapered waveguide.

Optionally, one or more of the optical beam management elements comprise a graded index (GRIN) lens such as a GRIN lens made by the laser modification of the refractive index of a material such as glass or a GRIN lens made by inserting a GRIN rod into a hole which is laser etched into a material of the optical interconnect component.

Optionally, one or more of the optical beam management elements comprise a 2D curved micromirror such as a 2D curved total internal reflection micromirror.

Optionally, each optical beam management element is separated from the end of the corresponding one of the plurality of integrated optical waveguides by a material of the optical interconnect component and/or by an air gap.

Optionally, the facet of the optical interconnect component is formed by etching, for example by etching the monolithic block of material.

Optionally, the ledge of the optical interconnect component is formed by etching, for example by etching the monolithic block of material.

Optionally, the facet of the photonic integrated circuit is formed by etching.

Optionally, the ledge of the photonic integrated circuit is formed by etching.

Optionally, the optical ports of the optical interconnect component and the ledge of the optical interconnect component are separated by a predetermined distance which matches a predetermined distance by which a plurality of optical ports of the photonic integrated circuit and a reference surface of the photonic integrated circuit are separated. Optionally, the step of the optical interconnect component is configured to allow engagement between the ledge of the optical interconnect component and the reference surface of the photonic integrated circuit without the ledge of the photonic integrated circuit engaging the optical interconnect component. Consequently, engagement between the ledge of the optical interconnect component and the reference surface of the photonic integrated circuit results in alignment of the optical ports of the optical interconnect component with the optical ports of the photonic integrated circuit in one dimension.

Optionally, the optical interconnect component comprises one or more fiducial markers disposed on the ledge of the optical interconnect component, each of the one or more fiducial markers being configured for alignment with one or more corresponding fiducial markers disposed on the reference surface of the photonic integrated circuit for alignment of the optical interconnect component and the photonic integrated circuit.

Optionally, the plurality of optical ports of the optical interconnect component and a reference surface of the optical interconnect component are separated by a predetermined distance which matches a predetermined distance by which the plurality of optical ports of the photonic integrated circuit and the ledge of the photonic integrated circuit are separated. Optionally, the step of the optical interconnect component is configured to allow engagement between the reference surface of the optical interconnect component and the ledge of the photonic integrated circuit without the ledge of the optical interconnect component engaging the photonic integrated circuit. Consequently, engagement between the reference surface of the optical interconnect component and the ledge of the photonic integrated circuit results in alignment of the optical ports of the optical interconnect component with the optical ports of the photonic integrated circuit in one dimension.

Optionally, the optical interconnect component comprises one or more fiducial markers disposed on the reference surface of the optical interconnect component, each of the one or more fiducial markers being configured for alignment with one or more corresponding fiducial markers disposed on the ledge of the photonic integrated circuit for alignment of the optical interconnect component and the photonic integrated circuit.

Optionally, the optical interconnect component comprises one or more alignment features, each alignment feature being configured to engage a corresponding complementary alignment feature of the photonic integrated circuit for passive alignment of the optical interconnect component and the photonic integrated circuit.

Optionally, the one or more alignment features of the optical interconnect component are formed integrally in the monolithic block of material.

Optionally, the optical interconnect component comprises one or more further alignment features, each further alignment feature being configured to engage a corresponding complementary alignment feature of the optical fibre ferrule component for passive alignment of the optical interconnect component and the optical fibre ferrule component.

Optionally, the one or more further alignment features of the optical interconnect component are formed integrally in the monolithic block of material. Optionally, the one or more further alignment features comprise one or more alignment pins or projections or one or more alignment holes. One or more of the alignment pins or projections may be formed integrally in the monolithic block of material. One or more of the alignment pins or projections may be formed separately from the monolithic block of material.

Optionally, the optical interconnect component and the optical fibre connector ferrule are configured to be detachably attached.

Optionally, the optical interconnect component and the optical fibre connector ferrule are configured to be pluggable or connectable.

Optionally, the optical ports of the optical interconnect component are arranged in a 1D array such as a uniform 1D array. Optionally, the optical ports of the optical interconnect component are arranged in a uniform 1D array on a pitch of less than 80 m.

Optionally, the optical interconnect component comprises a dispersive element, wherein the plurality of integrated optical waveguides includes a plurality of primary integrated optical waveguides and a secondary integrated optical waveguide, wherein each primary optical waveguide extends from a corresponding one of the optical ports to the dispersive element, and wherein the secondary optical waveguide extends from the dispersive element and ends at a position which is aligned with, but separated from, a corresponding one of the optical beam management elements.

Optionally, the dispersive element is configured to receive a plurality of different wavelengths via different primary integrated optical waveguides of the plurality of primary integrated optical waveguides and multiplex the plurality of different wavelengths into the secondary integrated optical waveguide or to receive a plurality of different wavelengths via the secondary integrated optical waveguide and demultiplex the plurality of different wavelengths into different primary integrated optical waveguides of the plurality of primary integrated optical waveguides.

Optionally, the dispersive element is formed integrally with the optical interconnect component.

Optionally, the dispersive element comprises one or more higher refractive index integrated optical waveguides defined in a layer of higher refractive index material which is disposed on a lower refractive index substrate of the optical interconnect component.

Optionally, one or more of the higher refractive index integrated optical waveguides are configured for evanescent coupling with one or more of the primary integrated optical waveguides and one or more of the higher refractive index integrated optical waveguides are configured for evanescent coupling with one or more of the secondary integrated optical waveguides.

Optionally, one or more of the higher refractive index integrated optical waveguides are aligned with one or more of the primary integrated optical waveguides and one or more of the higher refractive index integrated optical waveguides are aligned with one or more of the secondary integrated optical waveguides.

Optionally, the dispersive element is formed separately from the optical interconnect component and then attached to the optical interconnect component, for example by flip-chip bonding.

Optionally, the dispersive element comprises an arrayed waveguide grating (AWG), an Echelle grating or one or more bulk components such as one or more thin film interference filters located between the plurality of primary integrated optical waveguides and the secondary integrated optical waveguide.

Optionally, the one or more optical fibres comprise a plurality of optical fibres.

Optionally, each integrated optical waveguide of the plurality of integrated optical waveguides extends from the facet of the optical interconnect component so as to define the plurality of optical ports at the facet of the optical interconnect component.

Optionally, the one or more optical beam management elements comprise a plurality of optical beam management elements, and wherein an end of each integrated optical waveguide of the plurality of integrated optical waveguides is aligned with, but separated from, a corresponding one of the optical beam management elements of the optical interconnect component.

Optionally, the plurality of optical fibres comprises a 1D array of optical fibres such as a regular 1D array of optical fibres.

Optionally, the plurality of optical beam management elements comprises a 1D array of optical beam management elements such as a uniform 1D array of optical beam management elements.

Optionally, the plurality of optical fibres comprises a staggered arrangement of optical fibres.

Optionally, the plurality of optical beam management elements comprises a staggered arrangement of optical beam management elements.

Optionally, the plurality of optical fibres comprises a 2D array of optical fibres such as a regular 2D array of optical fibres.

Optionally, the plurality of optical beam management elements comprises a 2D array of optical beam management elements such as a uniform 2D array of optical beam management elements.

Optionally, formation of the optical interconnect component may comprise using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material of the optical interconnect component in one or more regions so as to modify the material of the monolithic block of the optical interconnect component in the one or more regions.

Optionally, formation of each integrated optical waveguide comprises using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material in one or more integrated optical waveguide regions so as to modify the material of the monolithic block in the one or more integrated optical waveguide regions.

Optionally, formation of each integrated optical waveguide comprises using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material in one or more integrated optical waveguide regions so as to modify a refractive index of the material of the monolithic block in the one or more integrated optical waveguide regions.

Optionally, formation of each optical beam management element comprises using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material in one or more optical beam management element regions so as to modify the material of the monolithic block in the one or more optical beam management element regions.

Optionally, formation of each optical beam management element comprises using the laser to inscribe the monolithic block of material in the one or more optical beam management element regions so as to modify a refractive index of the material of the monolithic block in the one or more optical beam management element regions.

Optionally, formation of each optical beam management element comprises using the laser to inscribe the monolithic block of material in the one or more optical beam management element regions so as to modify a chemical etchability of the material of the monolithic block in the one or more optical beam management element regions and subsequently removing the modified material of the monolithic block from the one or more optical beam management element regions, for example by chemical etching.

Optionally, formation of each optical beam management element comprises using the laser to inscribe the monolithic block of material in the one or more optical beam management element regions so as to ablate the material of the monolithic block in the one or more optical beam management element regions.

According to an aspect of the present disclosure there is provided an optical fibre connector ferrule for transmitting light between an optical interconnect component and one or more optical fibres, the optical fibre connector ferrule comprising:one or more optical beam management elements, each optical beam management element of the optical fibre connector ferrule configured for alignment with a corresponding optical beam management element of the optical interconnect component; andone or more optical fibre alignment structures,wherein each optical fibre alignment structure is configured for engagement with a corresponding optical fibre so that an end of the corresponding optical fibre is aligned with, but separated from, a corresponding one of the optical beam management elements of the optical fibre connector ferrule.

Optionally, the optical fibre connector ferrule comprises, or is formed in, a monolithic block of material such as glass, for example a monolithic block of fused silica.

Optionally, the one or more optical beam management elements are formed in the monolithic block of material.

Optionally, the one or more optical fibre alignment structures are formed in the monolithic block of material.

Optionally, wherein the one or more optical beam management elements of the optical fibre connector ferrule have a spatial configuration which matches a spatial configuration of the one or more optical beam management elements of the optical interconnect component.

Optionally, the optical fibre connector ferrule is configured for alignment with the optical interconnect component so as to align each optical beam management element of the optical fibre connector ferrule with a corresponding optical beam management element of the optical interconnect component for the transmission of light between each optical beam management element of the optical interconnect component and a corresponding optical beam management element of the optical fibre connector ferrule.

Optionally, the optical fibre connector ferrule comprises one or more alignment features, each alignment feature being configured to engage a corresponding complementary alignment feature of the optical interconnect component for passive alignment of the optical fibre connector ferrule and the optical interconnect component.

Optionally, the one or more alignment features of the optical fibre connector ferrule are formed in the monolithic block of material.

Optionally, the one or more alignment features of the optical fibre connector ferrule comprise one or more alignment pins or projections or one or more alignment holes. One or more of the alignment pins or projections may be formed integrally in the monolithic block of material. One or more of the alignment pins or projections may be formed separately from the monolithic block of material.

Optionally, the optical fibre connector ferrule and the optical interconnect component are configured to be detachably attached.

Optionally, the optical fibre connector ferrule and the optical interconnect component are configured to be pluggable or connectable.

Optionally, the one or more optical fibres comprise a plurality of optical fibres.

Optionally, the plurality of optical fibres comprises a 1D array of optical fibres such as a regular 1D array of optical fibres.

Optionally, the plurality of optical fibres comprises a staggered arrangement of optical fibres.

Optionally, the plurality of optical fibres comprises a 2D array of optical fibres such as a regular 2D array of optical fibres.

Optionally, each optical fibre comprises a plurality of optical fibre cores and wherein each optical fibre alignment structure is configured to engage a corresponding optical fibre so that an end of each optical fibre core of the corresponding optical fibre is aligned with, but separated from, a corresponding one of the optical beam management elements of the optical fibre connector ferrule.

Optionally, one or more of the optical beam management elements of the optical fibre connector ferrule comprise an optical beam collimating element or an optical beam focussing element.

Optionally, one or more of the optical beam management elements of the optical fibre connector ferrule comprise a microlens.

Optionally, one or more of the optical beam management elements of the optical fibre connector ferrule comprise a waveguide structure such as a segmented waveguide, or a tapered waveguide.

Optionally, one or more of the optical beam management elements of the optical fibre connector ferrule comprise a graded index (GRIN) lens such as a GRIN lens made by the laser modification of the refractive index of a material such as glass or a GRIN lens made by inserting a GRIN rod into a hole which is laser etched into a material of the optical fibre connector ferrule.

Optionally, one or more of the optical beam management elements of the optical fibre connector ferrule comprise a 2D curved micromirror such as a 2D curved total internal reflection micromirror.

According to an aspect of the present disclosure there is provided an optical interconnect assembly for transmitting light between a photonic integrated circuit and one or more optical fibres attached to an optical fibre connector ferrule, the optical interconnect assembly comprising:the optical interconnect component as described above; andthe optical fibre connector ferrule as described above,wherein each optical beam management element of the optical interconnect component is aligned with a corresponding optical beam management element of the optical fibre connector ferrule.

Optionally, wherein the one or more optical beam management elements of the optical fibre connector ferrule have a spatial configuration which matches a spatial configuration of the one or more optical beam management elements of the optical interconnect component.

Optionally, the optical fibre connector ferrule and the optical interconnect component are aligned so that each optical beam management element of the optical fibre connector ferrule is aligned with a corresponding optical beam management element of the optical interconnect component for the transmission of light between each optical beam management element of the optical interconnect component and a corresponding optical beam management element of the optical fibre connector ferrule.

Optionally, the optical fibre connector ferrule and the optical interconnect component are configured to be detachably attached.

Optionally, the optical fibre connector ferrule and the optical interconnect component are configured to be pluggable or connectable.

Optionally, the one or more optical fibres comprise a plurality of optical fibres.

Optionally, the plurality of optical fibres comprises a 1D array of optical fibres such as a regular 1D array of optical fibres.

Optionally, the plurality of optical fibres comprises a staggered arrangement of optical fibres.

Optionally, the plurality of optical fibres comprises a 2D array of optical fibres such as a regular 2D array of optical fibres.

Optionally, each optical fibre comprises a plurality of optical fibre cores and wherein each optical fibre alignment structure is configured to engage a corresponding optical fibre so that an end of each optical fibre core of the corresponding optical fibre is aligned with, but separated from, a corresponding one of the optical beam management elements of the optical fibre connector ferrule.

Optionally, the optical interconnect component and the optical fibre connector ferrule have one or more complementary inter-engaging alignment features for the passive alignment of the optical interconnect component and the optical fibre connector ferrule.

Optionally, the one or more complementary inter-engaging alignment features comprise one or more alignment pins or projections and one or more complementary alignment holes. One or more of the alignment pins or projections may be formed integrally in the monolithic block of material of the optical interconnect component or formed integrally in the monolithic block of material of the optical fibre connector ferrule. One or more of the alignment pins or projections may be formed separately from the monolithic block of material of the optical interconnect component and formed separately from the monolithic block of material of the optical fibre connector ferrule.

According to an aspect of the present disclosure there is provided an optical system comprising the optical interconnect assembly as described above, a photonic integrated circuit and one or more optical fibres, wherein the photonic integrated circuit and the optical interconnect component are attached, for example bonded, and each optical fibre is attached, for example bonded, to a corresponding optical fibre alignment structure of the optical fibre connector ferrule.

Optionally, the photonic integrated circuit comprises a plurality of integrated optical waveguides and a step formed at an edge of the photonic integrated circuit, wherein the step includes a ledge and a facet, and wherein each integrated optical waveguide of the photonic integrated circuit ends at the facet of the photonic integrated circuit so as to define a corresponding optical port at the facet of the photonic integrated circuit.

Optionally, the facet of the photonic integrated circuit is formed by etching.

Optionally, the ledge of the photonic integrated circuit is formed by etching.

Optionally, the photonic integrated circuit comprises or is formed from silicon, for example wherein the photonic integrated circuit is a silicon photonic integrated circuit.

Optionally, the optical ports of the optical interconnect component and the ledge of the optical interconnect component are separated by a predetermined distance which matches a predetermined distance by which the plurality of optical ports of the photonic integrated circuit and a reference surface of the photonic integrated circuit are separated. Optionally, the step of the optical interconnect component is configured to allow engagement between the ledge of the optical interconnect component and the reference surface of the photonic integrated circuit without the ledge of the photonic integrated circuit engaging the optical interconnect component. Consequently, engagement between the ledge of the optical interconnect component and the reference surface of the photonic integrated circuit results in alignment of the optical ports of the optical interconnect component with the optical ports of the photonic integrated circuit in one dimension.

Optionally, the optical interconnect component comprises one or more fiducial markers disposed on the ledge of the optical interconnect component, each of the one or more fiducial markers being configured for alignment with one or more corresponding fiducial markers disposed on the reference surface of the photonic integrated circuit for alignment of the optical interconnect component and the photonic integrated circuit.

Optionally, the plurality of optical ports of the optical interconnect component and a reference surface of the optical interconnect component are separated by a predetermined distance which matches a predetermined distance by which the plurality of optical ports of the photonic integrated circuit and the ledge of the photonic integrated circuit are separated. Optionally, the step of the optical interconnect component is configured to allow engagement between the reference surface of the optical interconnect component and the ledge of the photonic integrated circuit without the ledge of the optical interconnect component engaging the photonic integrated circuit. Consequently, engagement between the reference surface of the optical interconnect component and the ledge of the photonic integrated circuit results in alignment of the optical ports of the optical interconnect component with the optical ports of the photonic integrated circuit in one dimension.

Optionally, the optical interconnect component comprises one or more fiducial markers disposed on the reference surface of the optical interconnect component, each of the one or more fiducial markers being configured for alignment with one or more corresponding fiducial markers disposed on the ledge of the photonic integrated circuit for alignment of the optical interconnect component and the photonic integrated circuit.

Optionally, the one or more optical fibres comprise a plurality of optical fibres.

Optionally, the plurality of optical fibres comprises a 1D array of optical fibres such as a regular 1D array of optical fibres.

Optionally, the plurality of optical fibres comprises a staggered arrangement of optical fibres.

Optionally, the plurality of optical fibres comprises a 2D array of optical fibres such as a regular 2D array of optical fibres.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially toFIG.1Athere is shown a schematic side view of a first optical interconnect assembly generally designated2for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit4and a plurality of optical fibres6. The optical interconnect assembly2includes an optical interconnect component8and an optical fibre connector ferrule10. As will be described in more detail below, the optical interconnect component8is attached to the photonic integrated circuit4, and the plurality of optical fibres6are attached to the optical fibre connector ferrule10.

As shownFIGS.1A and1B, the photonic integrated circuit4includes a step generally designated20formed at an edge of the photonic integrated circuit4, wherein the step20includes a ledge22and a facet24. The photonic integrated circuit4further includes a plurality of integrated optical waveguides26, wherein each integrated optical waveguide26of the photonic integrated circuit4ends at the facet24of the photonic integrated circuit4so as to define a corresponding optical port28at the facet24of the photonic integrated circuit4. The plurality of integrated optical waveguides26are configured so that the optical ports28are arranged in a uniform 1D array. Each optical port28of the photonic integrated circuit4is defined at a predetermined distance from an upper reference surface29of the photonic integrated circuit4. One of ordinary skill in the art will understand that the ledge22and/or the facet24of the photonic integrated circuit4may be formed by etching. Moreover, the upper reference surface29of the photonic integrated circuit4may be polished.

As shownFIGS.1A and1C, the optical interconnect component8is formed in a monolithic block of material in the form of a monolithic block of fused silica9and includes a step generally designated30formed at an edge of the optical interconnect component8. The step30includes a ledge32and a facet34, wherein the facet34is configured for engagement with the facet24of the photonic integrated circuit4. One of ordinary skill in the art will understand that the ledge32of the optical interconnect component8and/or the facet34of the optical interconnect component8may be formed by etching the monolithic block of fused silica9.

The optical interconnect component8further includes a plurality of integrated optical waveguides36formed in the monolithic block of fused silica9, wherein each integrated optical waveguide36of the optical interconnect component8ends at the facet34of the optical interconnect component8so as to define a corresponding optical port38at the facet24of the optical interconnect component8. The plurality of integrated optical waveguides36are configured so that the optical ports38are arranged in a uniform 1D array which has a spatial configuration which matches a spatial configuration of the uniform 1D array of the optical ports28of the photonic integrated circuit4. Each optical port38of the optical interconnect component8is defined at a predetermined distance from the ledge32of the optical interconnect component8which matches the predetermined distance between each optical port28of the photonic integrated circuit4and the upper reference surface29of the photonic integrated circuit4. One of ordinary skill in the art will understand that the step30of the optical interconnect component8is configured to allow engagement between the ledge32of the optical interconnect component8and the upper reference surface29of the photonic integrated circuit4without the optical interconnect component8engaging the ledge22of the photonic integrated circuit4. Consequently, alignment of the optical ports28of the photonic integrated circuit4and the optical ports38of the optical interconnect component8is achieved automatically in the Z-direction when the ledge32of the optical interconnect component8engages the upper reference surface29of the photonic integrated circuit4.

Furthermore, the optical interconnect component8and the photonic integrated circuit4may be aligned in X and Y using a vision system. For example, the optical interconnect component8may comprise one or more fiducial markers (not shown inFIGS.1A-1C) disposed on the ledge32and the photonic integrated circuit4may comprise one or more corresponding fiducial markers (not shown inFIGS.1A-1C) disposed on the upper reference surface29of the photonic integrated circuit4. The one or more fiducial markers disposed on the ledge32of the optical interconnect component8and the one or more corresponding fiducial markers disposed on the upper reference surface29of the photonic integrated circuit4may be aligned in X and Y using a vision system.

Alternatively, the optical interconnect component8and the photonic integrated circuit4may comprise one or more complementary features (not shown inFIGS.1A-1C) which are configured for inter-engagement so as to align the optical interconnect component8and the photonic integrated circuit4in X and Y. For example, one of the optical interconnect component8and the photonic integrated circuit4may comprise a stand-off, pillar or a projection and the other of the optical interconnect component8and the photonic integrated circuit4may comprise a complementary recess for receiving the stand-off, pillar or projection so as to align the optical interconnect component8and the photonic integrated circuit4in X and Y.

In addition, although not shown inFIGS.1A-1C, the ledge32and/or the facet34of the optical interconnect component8may have one or more recesses or channels formed therein to assist with the flow of an adhesive fluid such as epoxy for the attachment of the optical interconnect component8and the photonic integrated circuit4. Such recesses or channels may, in effect, help to control the thickness of the bond-line between the optical interconnect component8and the photonic integrated circuit4and thereby provide a more robust attachment between the optical interconnect component8and the photonic integrated circuit4.

The optical interconnect component8further includes a plurality of optical beam management elements in the form of a plurality of microlenses40formed in the monolithic block of fused silica9at an end surface42of the optical interconnect component8and arranged in a uniform 2D array. Each of the microlenses40of the optical interconnect component8is aligned with, but separated from, an end44of a corresponding one of the plurality of integrated optical waveguides36.

The optical interconnect component8also includes a pair of alignment features in the form of a pair of alignment holes46formed in the monolithic block of fused silica9for use in aligning the optical interconnect component8and the optical fibre connector ferrule10.

As will be understood from the foregoing description ofFIGS.1A-1C, the plurality of integrated optical waveguides36of the optical interconnect component8are arranged to route light between the uniform 1D array of optical ports38of the optical interconnect component8and the uniform 2D array of microlenses40formed in the end surface42of the optical interconnect component8.

The optical fibre connector ferrule10is formed in a monolithic block of material in the form of a monolithic block of fused silica11and includes a plurality of optical beam management elements in the form of a plurality of microlenses50formed in an end surface52of the optical fibre connector ferrule10and arranged in a uniform 2D array. The spatial configuration of the 2D array of microlenses50of the optical fibre connector ferrule10matches the spatial configuration of the 2D array of microlenses40of the optical interconnect component8.

The optical fibre connector ferrule10further includes a plurality of optical fibre alignment structures in the form of a uniform 2D array of optical fibre alignment holes60formed in the monolithic block of fused silica11, each optical fibre alignment hole60being configured to accommodate an end section of a corresponding optical fibre6so that an end7of the corresponding optical fibre6is aligned with, but separated from, a corresponding one of the microlenses50of the optical fibre connector ferrule10.

Moreover, although not shown inFIG.1A, the optical fibre connector ferrule10includes one or more passages or channels extending between a surface of the optical fibre connector ferrule10and each optical fibre alignment hole60to assist with the flow of an adhesive fluid such as epoxy for the attachment of each optical fibre6in the corresponding optical fibre alignment hole60. The optical fibre connector ferrule10further includes alignment features in the form of pins70formed in the monolithic block of fused silica11, wherein each pin70is configured to be received in a corresponding one of the holes46of the optical interconnect component8for the passive alignment of the optical interconnect component8and the optical fibre connector ferrule10. Specifically, the alignment holes46of the optical interconnect component8are positioned relative to the microlenses40of the optical interconnect component8, and the pins70of the optical fibre connector ferrule10are positioned relative to the microlenses50of the optical fibre connector ferrule10to ensure that the microlenses40of the optical interconnect component8and the microlenses50of the optical fibre connector ferrule10are passively aligned when the pins70of the optical fibre connector ferrule10are inserted into the alignment holes46of the optical interconnect component8.

In use, when the pins70of the optical fibre connector ferrule10are inserted into the alignment holes46of the optical interconnect component8, light is transmitted between the integrated optical waveguides26of the photonic integrated circuit4and the optical fibres6via the optical interconnect component8and the optical fibre connector ferrule10. The 2D array of microlenses40of the optical interconnect component8and the 2D array of microlenses50of the optical fibre connector ferrule10serve to form a 2D array of expanded collimated optical beams which are transmitted horizontally between the optical interconnect component8and the optical fibre connector ferrule10thereby relaxing the alignment tolerance required between the optical interconnect component8and the optical fibre connector ferrule10for a given optical coupling efficiency.

From the foregoing description, it will be understood that the optical interconnect component8and the optical fibre connector ferrule10serve to optically couple the uniform 1D array of optical ports28of the photonic integrated circuit4and the uniform 2D array of optical fibres6thereby enabling higher density optical I/O than the optical I/O densities achievable using prior art optical interconnects. Moreover, the optical fibre connector ferrule10is pluggable or connectable to the optical interconnect component8in a horizontal direction i.e. in a direction which is parallel to a direction between the photonic integrated circuit4and the optical interconnect component8. The optical interconnect component8and the optical fibre connector ferrule10may also be detachably attachable. For example, although not shown inFIG.1A or1C, the optical interconnect component8may include one or more mechanical features such as one or more notches and the optical fibre connector ferrule10may include one or more mechanical features such as one or more arms, clips or clamps which are complementary to one or more notches of the optical interconnect component8and which are configured to engage the one or more notches of the optical interconnect component8for connecting, latching or holding the optical interconnect component8and the optical fibre connector ferrule10together.

Referring toFIG.2Athere is shown a schematic side view of a second optical interconnect assembly generally designated102for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit (not shown) and a plurality of optical fibres106. The optical interconnect assembly102includes an optical interconnect component108and an optical fibre connector ferrule110. As will be described in more detail below, the optical interconnect component108is configured for attachment to the photonic integrated circuit and the plurality of optical fibres106are attached to the optical fibre connector ferrule110.

As shown inFIGS.2A and2B, the optical interconnect component108is formed in a monolithic block of material in the form of a monolithic block of fused silica109and includes a step generally designated130formed at an edge of the optical interconnect component108. The step130includes a ledge132and a facet134, wherein the facet134is configured for engagement with a facet of a photonic integrated circuit. One of ordinary skill in the art will understand that the ledge132and/or the facet134of the optical interconnect component108may be formed by etching the monolithic block of fused silica109.

The optical interconnect component108further includes a plurality of integrated optical waveguides136formed in the monolithic block of fused silica109, wherein each integrated optical waveguide136of the optical interconnect component108ends at the facet134of the optical interconnect component108so as to define a corresponding optical port138at the facet124of the optical interconnect component108. The plurality of integrated optical waveguides136are configured so that the optical ports138are arranged in a uniform 1D array which has a spatial configuration which matches a spatial configuration of a uniform 1D array of optical ports of the photonic integrated circuit. Each optical port138of the optical interconnect component108is defined at a predetermined distance from the ledge132of the optical interconnect component108. One of ordinary skill in the art will understand that the step130of the optical interconnect component108is configured to allow engagement between the ledge132of the optical interconnect component108and an upper reference surface of the photonic integrated circuit without a ledge of the photonic integrated circuit engaging the optical interconnect component108. As described above in relation to the photonic integrated circuit4and the interconnect component8with reference toFIGS.1A-1C, this should result in the alignment of a plurality of optical ports of the photonic integrated circuit and the optical ports138of the optical interconnect component108in the Z-direction when the ledge132of the optical interconnect component108engages the upper reference surface of the photonic integrated circuit.

Furthermore, the optical interconnect component108and the photonic integrated circuit may be aligned in X and Y using a vision system. For example, the optical interconnect component108may comprise one or more fiducial markers (not shown inFIGS.2A and2B) disposed on the ledge132and the photonic integrated circuit may comprise one or more corresponding fiducial markers disposed on the upper reference surface of the photonic integrated circuit. The one or more fiducial markers disposed on the ledge132of the optical interconnect component108and the one or more corresponding fiducial markers disposed on the upper reference surface of the photonic integrated circuit may be aligned in X and Y using a vision system.

Alternatively, the optical interconnect component108and the photonic integrated circuit may comprise one or more complementary features (not shown inFIGS.2A and2B) which are configured for inter-engagement so as to align the optical interconnect component108and the photonic integrated circuit in X and Y. For example, one of the optical interconnect component108and the photonic integrated circuit may comprise a stand-off, pillar or a projection and the other of the optical interconnect component108and the photonic integrated circuit may comprise a complementary recess for receiving the stand-off, pillar or projection so as to align the optical interconnect component108and the photonic integrated circuit in X and Y.

In addition, although not shown inFIGS.2A and2B, the ledge132and/or the facet134of the optical interconnect component108may have one or more recesses or channels formed therein to assist with the flow of an adhesive fluid such as epoxy for the attachment of the optical interconnect component108and the photonic integrated circuit. Such recesses or channels may, in effect, help to control the thickness of the bond-line and thereby provide a more robust attachment between the optical interconnect component108and the photonic integrated circuit.

The optical interconnect component108further includes a plurality of optical beam management elements in the form of a plurality of 2D curved total internal reflection (TIR) micromirrors140formed on an underside of the optical interconnect component108in the monolithic block of fused silica109and arranged in a staggered pattern. Each of the 2D curved micromirrors140of the optical interconnect component108is aligned with, but separated from, an end144of a corresponding one of the plurality of integrated optical waveguides136.

The optical interconnect component108also includes one or more alignment features in the form of a pair of alignment holes146formed in the monolithic block of fused silica109for use in aligning the optical interconnect component108and the optical fibre connector ferrule110. The optical interconnect component108also includes one or more mechanical features in the form of a pair of notches172formed in the monolithic block of fused silica109for engagement by one or more arms, clips or clamps (not shown) of the optical fibre connector ferrule110so as to connect, latch or hold the optical interconnect component108and the optical fibre connector ferrule110together and thereby detachably attach the optical interconnect component108and the optical fibre connector ferrule110.

As will be understood from the foregoing description ofFIGS.2A and2B, the plurality of integrated optical waveguides136of the optical interconnect component108are arranged to route light between the uniform 1D array of optical ports138of the optical interconnect component108and the staggered arrangement of 2D curved micromirrors140. Specifically, alternate integrated optical waveguides136are used to route light up and down in Z to address 2D curved micromirrors140in different columns of the staggered arrangement of 2D curved micromirrors140.

The optical fibre connector ferrule110is formed in a monolithic block of material in the form of a monolithic block of fused silica111and includes a plurality of optical beam management elements in the form of a plurality of 2D curved total internal reflection (TIR) micromirrors150formed in an upper surface of the optical fibre connector ferrule110and arranged in a staggered pattern which matches the staggered pattern of the 2D curved micromirrors140of the optical interconnect component108.

The optical fibre connector ferrule110further includes a plurality of optical fibre alignment structures in the form of a staggered array of optical fibre alignment holes160formed in the monolithic block of fused silica111, each optical fibre alignment hole160being configured to accommodate an end section of a corresponding optical fibre106so that an end107of the corresponding optical fibre106is aligned with, but separated from, a corresponding one of the 2D curved micromirrors150of the optical fibre connector ferrule110. Moreover, although not shown inFIG.2A, the optical fibre connector ferrule110includes one or more passages or channels extending between a surface of the optical fibre connector ferrule110and each optical fibre alignment hole160to assist with the flow of an adhesive fluid such as epoxy for the attachment of each optical fibre106in the corresponding optical fibre alignment hole160.

The optical fibre connector ferrule110further includes pins170formed in the monolithic block of fused silica111, wherein each pin170is configured to be received in a corresponding one of the holes146of the optical interconnect component108for the passive alignment of the optical interconnect component108and the optical fibre connector ferrule110. Specifically, the alignment holes146of the optical interconnect component108are positioned relative to the 2D curved micromirrors140of the optical interconnect component108, and the pins170of the optical fibre connector ferrule110are positioned relative to the 2D curved micromirrors150of the optical fibre connector ferrule110to ensure that the 2D curved micromirrors140of the optical interconnect component108and the 2D curved micromirrors150of the optical fibre connector ferrule110are passively aligned when the pins170of the optical fibre connector ferrule110are inserted into the alignment holes146of the optical interconnect component108.

Although not shown inFIG.2A, it should be understood that the optical fibre connector ferrule110also includes one or more mechanical features such as one or more arms, clips or clamps (not shown) which are complementary to the notches172of the optical interconnect component108and which are configured to engage the notches172of the optical interconnect component108so as to connect, latch or hold the optical interconnect component108and the optical fibre connector ferrule110together so as to detachably attach the optical interconnect component108and the optical fibre connector ferrule110.

In use, when the pins170of the optical fibre connector ferrule110are inserted into the alignment holes146of the optical interconnect component108, light is transmitted between integrated optical waveguides of the photonic integrated circuit and the optical fibres106via the optical interconnect component108and the optical fibre connector ferrule110. The staggered arrangement of 2D curved micromirrors140of the optical interconnect component108and the staggered arrangement of 2D curved micromirrors150of the optical fibre connector ferrule110serve to form a staggered arrangement of expanded collimated optical beams which are transmitted vertically between the optical interconnect component108and the optical fibre connector ferrule110thereby relaxing the alignment tolerance required between the optical interconnect component108and the optical fibre connector ferrule110for a given optical coupling efficiency.

From the foregoing description, it will be understood that the optical interconnect component108and the optical fibre connector ferrule110serve to optically couple a uniform 1D array of optical ports of a photonic integrated circuit and the staggered array of optical fibres106thereby enabling higher density optical I/O than the optical I/O densities achievable using prior art optical interconnects. Moreover, the optical fibre connector ferrule110is pluggable or connectable to the optical interconnect component108in a vertical direction i.e. in a direction which is perpendicular to a direction between the photonic integrated circuit and the optical interconnect component108. This may be advantageous because plugging or unplugging the optical fibre connector ferrule110and the optical interconnect component108may exert forces which are perpendicular to the direction between the photonic integrated circuit and the optical interconnect component108, thereby exerting less force on a bond-line between the photonic integrated circuit and the optical interconnect component108and optionally also exerting less force on the photonic integrated circuit. Moreover, it should be understood that the photonic integrated circuit may extend at least partially underneath the optical interconnect component108so as to support the optical interconnect component108when the optical fibre connector ferrule110and the optical interconnect component108are plugged or unplugged.

FIG.3shows a schematic side view of part of a third optical interconnect assembly generally designated202for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit (not shown) and a plurality of optical fibres206which shares many like features with the second optical interconnect assembly102ofFIGS.2A and2B, with the features of the third optical interconnect assembly202ofFIG.3having the same reference numerals as like features of the second optical interconnect assembly102ofFIGS.2A and2Bincremented by “100”. The optical interconnect assembly202includes an optical interconnect component208and an optical fibre connector ferrule210. The optical interconnect component208is formed in a monolithic block of material in the form of a monolithic block of fused silica209and includes a plurality of integrated optical waveguides236and a plurality of 2D curved micromirrors240formed in an upper surface of the optical interconnect component208. The plurality of 2D curved micromirrors240are arranged in a staggered pattern like the staggered pattern of the 2D curved micromirrors140shown inFIG.2B. Each of the 2D curved micromirrors240of the optical interconnect component208is aligned with, but separated from, an end244of a corresponding integrated optical waveguide236. The optical fibre connector ferrule210is formed in a monolithic block of material in the form of a monolithic block of fused silica211and includes a plurality of 2D curved micromirrors250formed in a lower surface of the optical fibre connector ferrule210. The plurality of 2D curved micromirrors250is arranged in a staggered pattern which matches the staggered pattern of the 2D curved micromirrors240. The optical fibre connector ferrule210further includes a plurality of optical fibre alignment structures in the form of a staggered array of optical fibre alignment holes260formed in the monolithic block of fused silica211. Each of the 2D curved micromirrors250of the optical fibre connector ferrule210is aligned with, but separated from, an end207of a corresponding optical fibre206located in a corresponding optical fibre alignment hole260.

The optical interconnect component208includes alignment holes246formed in the monolithic block of fused silica209for use in aligning the optical interconnect component208and the optical fibre connector ferrule110. The optical fibre connector ferrule210includes pins270formed in the monolithic block of fused silica111for use in aligning the optical interconnect component208and the optical fibre connector ferrule110. Specifically, the alignment holes246of the optical interconnect component208are positioned relative to the microlenses240of the optical interconnect component208, and the pins270of the optical fibre connector ferrule210are positioned relative to the microlenses250of the optical fibre connector ferrule210to ensure that the microlenses240of the optical interconnect component208and the microlenses250of the optical fibre connector ferrule210are passively aligned when the pins270of the optical fibre connector ferrule210are inserted into the alignment holes246of the optical interconnect component208.

In use, when the pins270of the optical fibre connector ferrule210are inserted into the alignment holes246of the optical interconnect component208, light is transmitted between the integrated optical waveguides of the photonic integrated circuit and the optical fibres206via the optical interconnect component208and the optical fibre connector ferrule210. The staggered arrangement of microlenses240of the optical interconnect component208and the staggered arrangement of microlenses250of the optical fibre connector ferrule210serve to form a staggered arrangement of expanded collimated optical beams which are transmitted vertically between the optical interconnect component208and the optical fibre connector ferrule210thereby relaxing the alignment tolerance required between the optical interconnect component208and the optical fibre connector ferrule210for a given optical coupling efficiency.

In other aspects, the third optical interconnect assembly202ofFIG.3resembles the second optical interconnect assembly102ofFIG.2A.

Referring toFIG.4Athere is shown a schematic side view of a fourth optical interconnect assembly generally designated302for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit (not shown) and a plurality of optical fibres306. The optical interconnect assembly302includes an optical interconnect component308and an optical fibre connector ferrule310. As will be described in more detail below, the optical interconnect component308is configured for attachment to the photonic integrated circuit and the plurality of optical fibres306are attached to the optical fibre connector ferrule310.

The optical interconnect component308is formed in a monolithic block of material in the form of a monolithic block of fused silica309and includes a step generally designated330formed at an edge of the optical interconnect component308. The step330includes a ledge332and a facet334, wherein the facet334is configured for engagement with a facet of a photonic integrated circuit. One of ordinary skill in the art will understand that the ledge332and/or the facet334of the optical interconnect component308may be formed by etching the monolithic block of fused silica309.

The optical interconnect component308further includes a plurality of integrated optical waveguides336formed in the monolithic block of fused silica309, wherein each integrated optical waveguide336of the optical interconnect component308ends at the facet334of the optical interconnect component308so as to define a corresponding optical port338at the facet324of the optical interconnect component308. The plurality of integrated optical waveguides336are configured so that the optical ports338are arranged in a uniform 1D array which has a spatial configuration which matches a spatial configuration of a uniform 1D array of optical ports of the photonic integrated circuit. Each optical port338of the optical interconnect component308is defined at a predetermined distance below the ledge332of the optical interconnect component308. One of ordinary skill in the art will understand that the step330of the optical interconnect component308is configured to allow engagement between the ledge332of the optical interconnect component308and an upper reference surface of the photonic integrated circuit without a ledge of the photonic integrated circuit engaging the optical interconnect component308. As described above in relation to the photonic integrated circuit4and the interconnect component8with reference toFIGS.1A-1C, this should result in the alignment of a plurality of optical ports of the photonic integrated circuit and the optical ports338of the optical interconnect component308in the Z-direction when the ledge332of the optical interconnect component308engages the upper reference surface of the photonic integrated circuit.

Furthermore, the optical interconnect component308and the photonic integrated circuit may be aligned in X and Y using a vision system. For example, the optical interconnect component308may comprise one or more fiducial markers (not shown inFIGS.4A and4B) disposed on the ledge332and the photonic integrated circuit may comprise one or more corresponding fiducial markers disposed on the upper reference surface of the photonic integrated circuit. The one or more fiducial markers disposed on the ledge332of the optical interconnect component308and the one or more corresponding fiducial markers disposed on the upper reference surface of the photonic integrated circuit may be aligned in X and Y using a vision system.

Alternatively, the optical interconnect component308and the photonic integrated circuit may comprise one or more complementary features (not shown inFIGS.4A and4B) which are configured for inter-engagement so as to align the optical interconnect component308and the photonic integrated circuit in X and Y. For example, one of the optical interconnect component308and the photonic integrated circuit may comprise a stand-off, pillar or a projection and the other of the optical interconnect component308and the photonic integrated circuit may comprise a complementary recess for receiving the stand-off, pillar or projection so as to align the optical interconnect component1308and the photonic integrated circuit in X and Y.

In addition, although not shown inFIGS.4A and4B, the ledge332and/or the facet334of the optical interconnect component308may have one or more recesses or channels formed therein to assist with the flow of an adhesive fluid such as epoxy for the attachment of the optical interconnect component308and the photonic integrated circuit. Such recesses or channels may, in effect, help to control the thickness of the bond-line and thereby provide a more robust attachment between the optical interconnect component308and the photonic integrated circuit.

The optical interconnect component308further includes a plurality of optical beam management elements in the form of a plurality of 2D curved total internal reflection (TIR) micromirrors340formed on an underside of the optical interconnect component308in the monolithic block of fused silica309and arranged in a uniform 2D array. Each of the 2D curved micromirrors340of the optical interconnect component308is aligned with, but separated from, an end344of a corresponding one of the plurality of integrated optical waveguides336.

The optical interconnect component308also includes one or more alignment features in the form of a pair of alignment holes346formed in the monolithic block of fused silica309for use in aligning the optical interconnect component308and the optical fibre connector ferrule310. The optical interconnect component308also includes one or more mechanical features in the form of a pair of notches372formed in the monolithic block of fused silica309for engagement by one or more arms, clips or clamps (not shown) of the optical fibre connector ferrule310so as to connect, latch or hold the optical interconnect component308and the optical fibre connector ferrule310together and thereby detachably attach the optical interconnect component308and the optical fibre connector ferrule310.

As will be understood from the foregoing description ofFIGS.4A and4B, the plurality of integrated optical waveguides336of the optical interconnect component308are arranged to route light between the uniform 1D array of optical ports338of the optical interconnect component308and the uniform 2D array of 2D curved micromirrors340. Specifically, alternate integrated optical waveguides336are used to route light up and down in Z to address 2D curved micromirrors340in different columns of the 2D array of 2D curved micromirrors340.

The optical fibre connector ferrule310is formed in a monolithic block of material in the form of a monolithic block of fused silica311and includes a plurality of optical beam management elements in the form of a plurality of 2D curved total internal reflection (TIR) micromirrors350formed in an upper surface of the optical fibre connector ferrule310and arranged in a uniform 2D array. The spatial configuration of the 2D array of 2D curved micromirrors350of the optical fibre connector ferrule310matches the spatial configuration of the 2D array of 2D curved micromirrors340of the optical interconnect component308.

The optical fibre connector ferrule310further includes a plurality of optical fibre alignment structures in the form of a uniform 2D array of optical fibre alignment holes360formed in the monolithic block of fused silica311, each optical fibre alignment hole360being configured to accommodate an end section of a corresponding optical fibre306so that an end307of the corresponding optical fibre306is aligned with, but separated from, a corresponding one of the 2D curved micromirrors350of the optical fibre connector ferrule310. Moreover, although not shown inFIG.4A, the optical fibre connector ferrule310includes one or more passages or channels extending between a surface of the optical fibre connector ferrule310and each optical fibre alignment hole360to assist with the flow of an adhesive fluid such as epoxy for the attachment of each optical fibre306in the corresponding optical fibre alignment hole360.

The optical fibre connector ferrule310further includes pins370formed in the monolithic block of fused silica311, wherein each pin370is configured to be received in a corresponding one of the holes346of the optical interconnect component308for the passive alignment of the optical interconnect component308and the optical fibre connector ferrule310. Specifically, the alignment holes346of the optical interconnect component308are positioned relative to the 2D curved micromirrors340of the optical interconnect component308, and the pins370of the optical fibre connector ferrule310are positioned relative to the 2D curved micromirrors350of the optical fibre connector ferrule310to ensure that the 2D curved micromirrors340of the optical interconnect component308and the 2D curved micromirrors350of the optical fibre connector ferrule310are passively aligned when the pins370of the optical fibre connector ferrule310are inserted into the alignment holes346of the optical interconnect component308.

Although not shown inFIG.4A, it should be understood that the optical fibre connector ferrule310also includes one or more mechanical features such as one or more arms, clips or clamps (not shown) which are complementary to the notches372of the optical interconnect component308and which are configured to engage the notches372of the optical interconnect component308to connect, latch or hold the optical interconnect component308and the optical fibre connector ferrule310together and thereby detachably attach the optical interconnect component308and the optical fibre connector ferrule310.

In use, when the pins370of the optical fibre connector ferrule310are inserted into the alignment holes346of the optical interconnect component308, light is transmitted between integrated optical waveguides of the photonic integrated circuit and the optical fibres306via the optical interconnect component308and the optical fibre connector ferrule310. The 2D array of 2D curved micromirrors340of the optical interconnect component308and the 2D array of 2D curved micromirrors350of the optical fibre connector ferrule310serve to form a 2D array of expanded collimated optical beams which are transmitted vertically between the optical interconnect component308and the optical fibre connector ferrule310thereby relaxing the alignment tolerance required between the optical interconnect component308and the optical fibre connector ferrule310for a given optical coupling efficiency.

From the foregoing description, it will be understood that the optical interconnect component308and the optical fibre connector ferrule310serve to optically couple a uniform 1D array of optical ports of a photonic integrated circuit and the uniform 2D array of optical fibres306thereby enabling higher density optical I/O than the optical I/O densities achievable using prior art optical interconnects. Moreover, the optical fibre connector ferrule310is pluggable or connectable to the optical interconnect component308in a vertical direction i.e. in a direction which is perpendicular to a direction between the photonic integrated circuit and the optical interconnect component308. This may be advantageous because plugging or unplugging the optical fibre connector ferrule310and the optical interconnect component308may exert forces which are perpendicular to the direction between the photonic integrated circuit and the optical interconnect component308, thereby exerting less force on a bond-line between the photonic integrated circuit and the optical interconnect component308and, optionally, also exerting less force on the photonic integrated circuit. Moreover, it should be understood that the photonic integrated circuit may extend at least partially underneath the optical interconnect component308so as to support the optical interconnect component308when the optical fibre connector ferrule310and the optical interconnect component308are plugged or unplugged.

FIG.5shows a schematic side view of part of a fifth optical interconnect assembly generally designated402for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit (not shown) and a plurality of optical fibres406which shares many like features with the fourth optical interconnect assembly302ofFIGS.4A and4B, with the features of the fifth optical interconnect assembly402ofFIG.5having the same reference numerals as like features of the fourth optical interconnect assembly302ofFIGS.4A and4Bincremented by “100”. The optical interconnect assembly402includes an optical interconnect component408and an optical fibre connector ferrule410. The optical interconnect component408is formed in a monolithic block of material in the form of a monolithic block of fused silica409and includes a plurality of integrated optical waveguides436and a plurality of 2D curved micromirrors440formed in an upper surface of the optical interconnect component408. The plurality of 2D curved micromirrors440are arranged in a uniform 2D array like the uniform 2D array of 2D curved micromirrors340shown inFIG.4B. Each of the 2D curved micromirrors440of the optical interconnect component408is aligned with, but separated from, an end444of a corresponding integrated optical waveguide436. The optical fibre connector ferrule410is formed in a monolithic block of material in the form of a monolithic block of fused silica411and includes a plurality of 2D curved micromirrors450formed in a lower surface of the optical fibre connector ferrule410and arranged in a uniform 2D array which matches the uniform 2D array of the 2D curved micromirrors440. The optical fibre connector ferrule410further includes a plurality of optical fibre alignment structures in the form of a uniform 2D array of optical fibre alignment holes460. Each of the 2D curved micromirrors450of the optical fibre connector ferrule410is aligned with, but separated from, an end407of a corresponding optical fibre406located in a corresponding optical fibre alignment hole460.

The optical interconnect component408includes alignment holes446formed in the monolithic block of fused silica409for use in aligning the optical interconnect component408and the optical fibre connector ferrule410. The optical fibre connector ferrule410includes pins470formed in the monolithic block of fused silica411for use in aligning the optical interconnect component408and the optical fibre connector ferrule410. Specifically, the alignment holes446of the optical interconnect component408are positioned relative to the microlenses440of the optical interconnect component408, and the pins470of the optical fibre connector ferrule410are positioned relative to the microlenses450of the optical fibre connector ferrule410to ensure that the microlenses440of the optical interconnect component408and the microlenses450of the optical fibre connector ferrule410are passively aligned when the pins470of the optical fibre connector ferrule410are inserted into the alignment holes446of the optical interconnect component408.

In use, when the pins470of the optical fibre connector ferrule410are inserted into the alignment holes446of the optical interconnect component408, light is transmitted between the integrated optical waveguides of the photonic integrated circuit and the optical fibres406via the optical interconnect component408and the optical fibre connector ferrule410. The 2D array of microlenses440of the optical interconnect component408and the 2D array of microlenses450of the optical fibre connector ferrule410serve to form a 2D array of expanded collimated optical beams which are transmitted vertically between the optical interconnect component408and the optical fibre connector ferrule410thereby relaxing the alignment tolerance required between the optical interconnect component408and the optical fibre connector ferrule410for a given optical coupling efficiency.

In other aspects, the fifth optical interconnect assembly402ofFIG.5resembles the fourth optical interconnect assembly302ofFIG.4A.

FIG.6shows a wavelength multiplexing or a wavelength demultiplexing optical interconnect component generally designated508for transmitting light between a photonic integrated circuit in the form of a silicon photonic integrated circuit (not shown) and one or more optical fibres (not shown) attached to an optical fibre connector ferrule (not shown). The wavelength mux/demux optical interconnect component508and the optical fibre connector ferrule are pluggable or connectable i.e. the wavelength mux/demux optical interconnect component508and the optical fibre connector ferrule are configured to be detachably attached.

The wavelength mux/demux optical interconnect component508is formed in a monolithic block of material in the form of a monolithic block of fused silica509and includes a step generally designated530formed at an edge of the wavelength mux/demux optical interconnect component508. The step530includes a ledge532and a facet534, wherein the facet534is configured for engagement with a facet of a photonic integrated circuit. One of ordinary skill in the art will understand that the ledge532and/or the facet534of the wavelength mux/demux optical interconnect component508may be formed by etching the monolithic block of fused silica509.

The wavelength mux/demux optical interconnect component508further comprises a plurality of primary integrated optical waveguides536a, a plurality of secondary integrated optical waveguides536baand a dispersive element580in the form of an AWG formed in the monolithic block of fused silica509.

Each primary integrated optical waveguide536aof the wavelength mux/demux optical interconnect component508ends at the facet534of the wavelength mux/demux optical interconnect component508so as to define a corresponding optical port538at the facet534of the wavelength mux/demux optical interconnect component508. Each primary optical waveguide536aextends from a corresponding one of the optical ports538to the dispersive element580. The plurality of primary integrated optical waveguides536aare configured so that the optical ports538are arranged in a uniform 1D array which has a spatial configuration which matches a spatial configuration of a uniform 1D array of optical ports of the photonic integrated circuit. Each optical port538of the wavelength mux/demux optical interconnect component508is defined at a predetermined distance from the ledge532of the wavelength mux/demux optical interconnect component508. One of ordinary skill in the art will understand that the step530of the wavelength mux/demux optical interconnect component508is configured to allow engagement between the ledge532of the wavelength mux/demux optical interconnect component508and an upper reference surface of the photonic integrated circuit without a ledge of the photonic integrated circuit engaging the wavelength mux/demux optical interconnect component508. As described above in relation to the photonic integrated circuit4and the interconnect component8with reference toFIGS.1A-1C, this should result in the alignment of a plurality of optical ports of the photonic integrated circuit and the optical ports538of the wavelength mux/demux optical interconnect component508in the Z-direction when the ledge532of the wavelength mux/demux optical interconnect component508engages the upper reference surface of the photonic integrated circuit.

As described above in relation to the photonic integrated circuit4and the interconnect component8with reference toFIGS.1A-1C, alignment of the wavelength mux/demux optical interconnect component508and the photonic integrated circuit in X and Y may be achieved using fiducial markers and a vision system. Alternatively, the wavelength mux/demux optical interconnect component508and the photonic integrated circuit may comprise one or more complementary alignment features configured for inter-engagement so as to align the wavelength mux/demux optical interconnect component508and the photonic integrated circuit in X and Y.

The optical interconnect component508further includes a plurality of optical beam management elements in the form of a plurality of microlenses540formed on an end surface of the optical interconnect component508in the monolithic block of fused silica509. Each secondary optical waveguide536bextends from the dispersive element580. Each of the microlenses540of the optical interconnect component508is aligned with, but separated from, an end of a corresponding one of the plurality of secondary integrated optical waveguides536b.

The optical interconnect component508also includes one or more alignment features in the form of a pair of alignment holes546formed in the monolithic block of fused silica509for use in aligning the optical interconnect component508and an optical fibre connector ferrule (not shown). The optical interconnect component508also includes one or more mechanical features in the form of a pair of notches572formed in the monolithic block of fused silica509for engagement by one or more arms, clips or clamps of an optical fibre connector ferrule (not shown) so as to connect, latch or hold the optical interconnect component508and the optical fibre connector ferrule together and thereby detachably attach the optical interconnect component508and the optical fibre connector ferrule.

In use, the dispersive element580receives a plurality of different wavelengths via different primary integrated optical waveguides536aand multiplexes the plurality of different wavelengths into one or more of the secondary integrated optical waveguides536bor the dispersive element580receives a plurality of different wavelengths via one of the secondary integrated optical waveguides536band demultiplexes the plurality of different wavelengths into different primary integrated optical waveguides536aof the plurality of primary integrated optical waveguides536a.

From the foregoing description of the wavelength mux/demux optical interconnect component508, it will be understood that the optical interconnect component508and the optical fibre connector ferrule (not shown) serve to optically couple a uniform 1D array of optical ports of a photonic integrated circuit and one or more optical fibres thereby enabling higher density optical I/O than the optical I/O densities achievable using prior art optical interconnects whilst also providing optical wavelength mux/demux functionality. Moreover, the optical fibre connector ferrule is pluggable or connectable to the optical interconnect component508in a horizontal direction i.e. in a direction which is parallel to a direction between the photonic integrated circuit and the optical interconnect component508.

In other respects the structure and operation of the wavelength mux/demux optical interconnect component508ofFIG.6resembles the structure and operation of the optical interconnect component8ofFIGS.1A-1C.

Referring now toFIG.7there is shown an optical fibre connector ferrule610formed in a monolithic block of material in the form of a monolithic block of fused silica611for transmitting light between an optical interconnect component (not shown) and a plurality of optical fibres606, wherein each optical fibre606includes a plurality of optical fibre cores606a. The optical fibre connector ferrule610includes a plurality of optical beam management elements in the form of a plurality of microlenses650formed in the monolithic block of fused silica611, each microlens650configured for alignment with a corresponding microlens40of the optical interconnect component8ofFIG.1C. The optical fibre connector ferrule610further includes a plurality of optical fibre alignment structures in the form of a plurality of holes660formed in the monolithic block of fused silica611, each hole660configured to receive an end section of a corresponding one of the optical fibres606so that each optical fibre core606aat an end607of the corresponding optical fibre606is aligned with, but separated from, a corresponding one of the microlenses650.

The optical fibre connector ferrule610is configured for connection to the optical interconnect component8so as to align each microlenses650of the optical fibre connector ferrule610with a corresponding microlens40of the optical interconnect component8. The optical fibre connector ferrule610and the optical interconnect component8are configured to be pluggable or connectable. The optical fibre connector ferrule610and the optical interconnect component8may be configured to be detachably attached. The optical interconnect component8includes alignment holes46for use in aligning the optical interconnect component8and the optical fibre connector ferrule610. The optical fibre connector ferrule610includes pins670formed in the monolithic block of fused silica611for use in aligning the optical interconnect component8and the optical fibre connector ferrule610. Specifically, the alignment holes46of the optical interconnect component8are positioned relative to the microlenses40of the optical interconnect component8, and the pins670of the optical fibre connector ferrule610are positioned relative to the microlenses650of the optical fibre connector ferrule610to ensure that the microlenses40of the optical interconnect component8and the microlenses650of the optical fibre connector ferrule610are passively aligned when the pins670of the optical fibre connector ferrule610are inserted into the alignment holes46of the optical interconnect component8.

From the foregoing description of the optical fibre connector ferrule610, it will be understood that the optical fibre connector ferrule610may be used in conjunction with the optical interconnect component8for optically coupling a uniform 1D array of optical ports of a photonic integrated circuit and one or more optical fibres thereby enabling higher density optical I/O than the optical I/O densities achievable using prior art optical interconnects. Moreover, the optical fibre connector ferrule610is pluggable or connectable to the optical interconnect component8in a horizontal direction i.e. in a direction which is parallel to a direction between the photonic integrated circuit and the optical interconnect component8.

Formation of the optical interconnect component8,108,208,308,408,508may comprise using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material9,109,209,309,409,509of the optical interconnect component8,108,208,308,408,508in one or more regions so as to modify the material of the monolithic block9,109,209,309,409,509of the optical interconnect component8,108,208,308,408,508in the one or more regions.

For example, formation of each integrated optical waveguide36,136,236,336,436,536a,536bmay comprise using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material9,109,209,309,409,509in one or more integrated optical waveguide regions so as to modify the material of the monolithic block9,109,209,309,409,509in the one or more integrated optical waveguide regions.

Formation of each optical beam management element40,140,240,340,440,540may comprise using a laser such as an ultrafast laser or a femtosecond laser to inscribe the monolithic block of material9,109,209,309,409,509in one or more optical beam management element regions so as to modify the material of the monolithic block9,109,209,309,409,509in the one or more optical beam management element regions.

Formation of each optical beam management element40,140,240,340,440,540may comprise using the laser to inscribe the monolithic block of material9,109,209,309,409,509in the one or more optical beam management element regions so as to modify a refractive index of the material of the monolithic block9,109,209,309,409,509in the one or more optical beam management element regions.

Formation of each optical beam management element40,140,240,340,440,540may comprise using the laser to inscribe the monolithic block of material9,109,209,309,409,509in the one or more optical beam management element regions so as to modify a chemical etchability of the material of the monolithic block9,109,209,309,409,509in the one or more optical beam management element regions and subsequently removing the modified material of the monolithic block9,109,209,309,409,509from the one or more optical beam management element regions, for example by chemical etching.

Formation of each optical beam management element40,140,240,340,440,540may comprise using the laser to inscribe the monolithic block of material9,109,209,309,409,509in the one or more optical beam management element regions so as to ablate the material of the monolithic block9,109,209,309,409,509in the one or more optical beam management element regions.

One of ordinary skill in the art will understand that various modifications may be made to the embodiments of the present disclosure described above without departing from the scope of the present invention as defined according to the appended claims. For example, although many of the optical fiber connector ferrules10,110,210,310,410described above are configured for use with a uniform 2D array of optical fibres, other optical fiber connector ferrules may be configured for use with a uniform 1D array of optical fibres on a pitch which is greater than a pitch of the integrated optical waveguides of the photonic integrated circuit4. In such an embodiment, the plurality of beam management elements of the optical fiber connector ferrule may be arranged in a uniform 1D array with each beam management element aligned with, but separated from, an end of a corresponding one of the optical fibres. The optical interconnect component may also comprise a plurality of beam management elements arranged in a uniform 1D array with the same pitch as the uniform 1D array of beam management elements of the optical fiber connector ferrule. Moreover, the plurality of integrated optical waveguides may fan-out from the plurality of optical ports of the optical interconnect component to the uniform 1D array of beam management elements of the optical interconnect component.

The ledges32,132,332of the optical interconnect components8,108,308are described with reference toFIGS.1A-1C,2A,2B and4A and4B, as engaging an upper reference surface of a photonic integrated circuit without the optical interconnect components8,108,308engaging a ledge of the photonic integrated circuit so as to align a 1D array of optical ports38,138,338of the optical interconnect components8,108,308with a 1D array of optical ports of the photonic integrated circuit in Z. For example, with reference toFIGS.1A-1C, the ledge32of the optical interconnect component8is described as engaging the upper reference surface29of the photonic integrated circuit4without the optical interconnect component8engaging the ledge22of the photonic integrated circuit4so as to align the 1D array of optical ports38of the optical interconnect component8with the 1D array of optical ports28of the photonic integrated circuit4in Z. In alternative embodiments, a ledge of the photonic integrated circuit may engage a lower reference surface of the optical interconnect component without the photonic integrated circuit engaging a ledge of the optical interconnect component so as to align the 1D array of optical ports38,138,338of the optical interconnect components8,108,308with a 1D array of optical ports28of the photonic integrated circuit in Z. For example, with reference toFIGS.1A-1C, a ledge22of the photonic integrated circuit may engage a lower reference surface in the form of the underside of the optical interconnect component8without the photonic integrated circuit4engaging the ledge32of the optical interconnect component8so as to align the 1D array of optical ports38,138,338of the optical interconnect components8,108,308with a 1D array of optical ports28of the photonic integrated circuit4in Z.

In some embodiments, the facet of the photonic integrated circuit may be diced rather than etched. For example, the facet24of the photonic integrated circuit4may be diced rather than etched. In other embodiments, the photonic integrated circuit may not have a ledge, but may instead have just a facet.

In the embodiment ofFIG.6, the dispersive element580may comprise one or more higher refractive index integrated optical waveguides defined in a layer of higher refractive index material which is disposed on a lower refractive index substrate of the optical interconnect component508. The one or more of the higher refractive index integrated optical waveguides may be configured for evanescent coupling with one or more of the primary integrated optical waveguides536aand one or more of the higher refractive index integrated optical waveguides may be configured for evanescent coupling with one or more of the secondary integrated optical waveguides536b. One or more of the higher refractive index integrated optical waveguides may be aligned with one or more of the primary integrated optical waveguides536aand one or more of the higher refractive index integrated optical waveguides may be aligned with one or more of the secondary integrated optical waveguides536b. Rather than the dispersive element being formed integrally with the optical interconnect component, the dispersive element may be formed separately from the optical interconnect component and then attached to the optical interconnect component, for example by flip-chip bonding. Rather than the dispersive element comprising an arrayed waveguide grating (AWG)580, the dispersive element may comprise an Echelle grating or one or more bulk components such as one or more thin film interference filters located between the plurality of primary integrated optical waveguides536aand one or more of the secondary integrated optical waveguide536b.

As an alternative to the use of microlenses such as microlenses40,540,50,650expanded collimated optical beams can be created using waveguide structures such as segmented waveguides or tapered waveguides. Alternatively, expanded collimated optical beams can be created using graded index (GRIN) lenses such as GRIN lenses made by the laser modification of the refractive index of a material such as glass or GRIN lenses made by inserting GRIN rods into holes which are laser etched into the optical interconnect component8,508and/or the optical fibre connector ferrule10,610.

Although the optical interconnect components108,308having 2D curved TIR micromirrors140,340formed on a lower side thereof are described for use with optical fibre connector ferrules110,310having 2D curved TIR micromirrors150,350formed on an upper side thereof, the optical interconnect components108,308may be used with the optical fibre connector ferrules210,410having 2D curved micromirrors250,450formed on a lower side thereof. Similarly, although the optical fibre connector ferrules110,310having 2D curved TIR micromirrors150,350formed on an upper side thereof are described for use with optical interconnect components108,308having 2D curved TIR micromirrors140,340formed on a lower side thereof, the optical fibre connector ferrules110,310may be used with the optical interconnect components208,408having 2D curved micromirrors240,440formed on an upper side thereof.

Each feature disclosed or illustrated in the present specification may be incorporated in any embodiment, either alone, or in any appropriate combination with any other feature disclosed or illustrated herein. In particular, one of ordinary skill in the art will understand that one or more of the features of the embodiments of the present disclosure described above with reference to the drawings may produce effects or provide advantages when used in isolation from one or more of the other features of the embodiments of the present disclosure and that different combinations of the features are possible other than the specific combinations of the features of the embodiments of the present disclosure described above.

The skilled person will understand that in the preceding description and appended claims, positional terms such as ‘above’, ‘along’, ‘side’, etc. are made with reference to conceptual illustrations, such as those shown in the appended drawings. These terms are used for ease of reference but are not intended to be of limiting nature. These terms are therefore to be understood as referring to an object when in an orientation as shown in the accompanying drawings.

Use of the term “comprising” when used in relation to a feature of an embodiment of the present disclosure does not exclude other features or steps. Use of the term “a” or “an” when used in relation to a feature of an embodiment of the present disclosure does not exclude the possibility that the embodiment may include a plurality of such features.

The use of any reference signs in the claims should not be construed as limiting the scope of the claims.