Optical assembly and method of manufacturing the same
Patent Information
- Application Number
- KR1020267027988
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-01-29
- Filing Date
- 2025-01-28
- Publication Date
- 2026-09-17
Smart Images
Figure PCT00001_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to the field of integrated optical systems, and more particularly to waveguide structures for optical connections between optical components, particularly between planar integrated photonic systems (chip-to-chip connections) or between a planar integrated photonic system and a glass fiber (fiber-to-chip connections). The present invention relates to an optical assembly and a method for manufacturing the same, wherein its integrity and optical properties are maintained as much as possible even under changing ambient conditions. Background Technology
[0002] In integrated optical systems, different material platforms, preferably referred to as "integrated optical systems," indium phosphide (InP), silicon (SiP), silicon nitride (SiN), polymers, and glass, are used for optical assemblies, and each material platform has its specific advantages and disadvantages. The use of different material platforms, known as "hybrid integration," offers the possibility of combining the distinct advantages of different material platforms. However, cost-effective and technically feasible integration is not trivial. Conventional techniques referred to as "butt coupling" involve the direct coupling of two components to be aligned with precision in the lower micrometer range or even the sub-micrometer range. This often requires slow and complex active alignment methods in which coupling efficiency is continuously monitored while the positioning of the components is optimized. Furthermore, various mode fields of the components must be directly adapted on each component. The mode field transducers required for this purpose occupy a significant proportion of the chip area and / or require additional process steps during production. Another approach involves using additional components, preferably microlenses, prisms, or micromechanical carriers, to adapt the emission direction of the light source and the size of the mode field between optical components resulting in relatively large functional groups. Additionally, in an additional approach, for example, III-V components (InP components) are mounted on a SiP chip. This approach not only consumes a large amount of space on the chip but also presents a challenge regarding heat dissipation of the III-V components by the underlying silicon-on-insulator (SOI) substrate, due to the relatively low thermal conductivity of the embedded oxide.
[0003] Additionally, many optical components require optical connections to glass fibers. For example, as in hybrid integration between InP and SiP material platforms, conventional approaches involve the use of the butt coupling described above or optical free-beam paths by optical elements, particularly lenses or mirrors. In these methods, active alignment techniques are used just as frequently. Glass fibers are fixed in optimized positions using laser welding or UV epoxy bonding processes, requiring alignment tolerances in the submicron range. This process is performed at the component level or the package level and results in undesirable throughput limitations, with cycle times ranging from a few minutes to tens of minutes per package, depending on the complexity of the photonic components to be mounted.
[0004] Photon wire bonding (PWB) is a method for the automated 3D fabrication of optical connections. The three-dimensional (3D) nanoprinting of free-form optical waveguides is based on two-photon polymerization (TPP) technology using femtosecond lasers with resolution below the diffraction limit. The morphology of photon wire bonds can be adapted across different material platforms for the waveguide dimensions of components, i.e., corresponding mode field profiles. Typical waveguide dimensions on optical chips that can be connected using photon wire bonds range from less than 1 µm for Si-WG and approximately 2 to 5 µm for InP chips, with core diameters of approximately 10 µm for single-mode fibers and 62.5 µm for multi-mode fibers. The position and trajectory of photon wire bonds can be adapted to precise locations on the chip, eliminating the need for highly precise chip alignment, which makes the technology suitable for automated mass production. PWB enables low-loss coupling between different interfaces.
[0005] For optical connections of single-mode waveguides, photon wire bonds must be dimensioned in such a way that they become single-mode. For common dimensions, this requires cladding the photon wire bonds with a protective structure composed of a selected protective material that provides the desired optical refractive index. Additionally, the protective structure must stabilize the photon wire bonds in such a way so that the optical assembly can operate under a wide range of ambient conditions over extended periods. Due to the dimensions of photon wire bonds, which have widths and thicknesses of several micrometers and lengths of several hundred micrometers, it is a challenge to provide optical connections using photon wire bonds in such a way that function well under different ambient conditions. For example, if the optical assembly is exposed to various temperatures ranging from -40°C to +85°C, the optical properties must nevertheless not change significantly or even degrade. Optical assemblies for optically connecting two or more optical components comprise a number of different materials having fundamentally different properties, ranging from the mechanical carrier and the material of the optical chip to the materials of the photon wire bonds and the protective structure. Under changing ambient conditions, various materials can change their properties, for example, their thermal expansion, differently.
[0006] To manufacture an optical assembly, typically at least one optical component is coupled to a component carrier. In this case, the optical component is generally a discrete component on its own substrate. Two optical elements integrated on the same substrate, each having its own coupling point, are counted as one component. The component includes, for example, an optical free-form structure, specifically at least one optical coupling point to which a photon wire bond is connected and which is at least partially surrounded by a protective structure. In this case, the connected free-form structure does not necessarily need to be in mechanical contact with the coupling point; it is important that it is in a fixed mechanical relationship with the coupling point and that light emitted from the optical coupling point can interact with the free-form structure.
[0007] According to the prior art, for example, components intended to be connected using photon wire bonds are fastened side by side on a component carrier, and the heights of the components are typically adapted to each other through the component carrier. The literature [Lindenmann et al., J., Lightwave Technol. 33, 755-760 (2015)] describes an optical assembly comprising two optical components, a glass fiber, and a silicon photon chip fastened on a common component carrier. In this case, the component carrier is designed to have a step to guide the coupling points of the optical components to approximately the same height. The photon wire bond connecting the coupling points is surrounded by a protective structure between the optical components. This optical assembly has the disadvantage described above in that the protective structure fills the space under the photon wire bond up to at least the assembly plane of the optical components, so that the minimum volume is predetermined by the height of at least one component. As a result, in the event of a temperature change, the entire volume of the protective structure under the photon wire bond will expand or contract and apply force to the photon wire bond, which is detrimental to the optical properties and long-term stability of the photon wire bond.
[0008] The literature [Blaicher et al., Light: Science & Applications (2020) 9:71] proposes various concepts for connecting optical components using photon wire bonds. What they have in common is that the gap between optical components has a depth of at least 100 μm and extends to the assembly plane of at least one of the components. As a result, in the event of changes in ambient conditions, the protective structure existing as a coating on the photon wire bond can expand significantly and deform the photon wire bond, which is detrimental to its optical properties and long-term stability.
[0009] In addition to the approaches described in the two literatures above, the literature [Darcie et al., Proc. SPIE 11691, Silicon Photonics XVI, 116910C (2021)] also discloses an exemplary arrangement for connecting two optical components, wherein one optical component (e.g., a laser or glass fiber) is coupled to another component (e.g., a SiP chip) within a recess, resulting in coupling points being approximately at a single level and connected using a free-form structure. In this case, the component simultaneously acts as a component carrier. Here, too, the spatial region between the free-form structure and the assembly plane is completely filled with a protective structure. Furthermore, the depth of the gap is predetermined by the thickness of the component and cannot be selected independently thereof. An additional disadvantage of this approach is that the laser emits its heat directly to the SiP chip, which can lead to undesirable heating of the SiP chip. However, independent heat dissipation cannot be achieved with this type of optical assembly configuration. The problem to be solved
[0010] Furthermore, the object of the present invention is to provide an optical assembly and a method for manufacturing an optical assembly that at least partially overcomes the aforementioned disadvantages and limitations of the prior art.
[0011] The object of the present invention is to provide an optical assembly in which, despite changes in ambient conditions—particularly preferably a temperature of ±260 K, more preferably ±80 K, or a change in ambient pressure, or the occurrence of vibration—changes in the relative positions of the optical components, the optical free-form structure, and the protective structure for the optical free-form structure are very small, so as not to cause significant changes in the optical properties of the optical assembly. Typically, expected changes in ambient conditions include temperature changes of -40°C to +85°C or -60°C to +125°C, vibrations of the optical assembly at 10 Hz to 2 kHz with an acceleration of up to 20 g, and mechanical shocks with an acceleration of up to 500 g within milliseconds.
[0012] The change in optical loss of an optical free-form structure used to couple at least two optical components should preferably be up to 2 dB, particularly up to 0.5 dB, when typical variations in ambient conditions occur, particularly a temperature change of ±80 K. In a photon wire bond or printed 3D microlens integrated between two optical components on a common carrier as an optical free-form structure, the change in the optical free-form structure resulting from the relative movement of the protective structure surrounding the optical free-form structure with respect to the position of the coupling point on the optical components should preferably be up to 20 µm, particularly preferably up to 6 µm.
[0013] For a solution suitable for general industrial applications as much as possible, individual processing steps on the optical components are not required, but it would be additionally desirable if standardized, commercially available optical components could be used instead. It would be particularly desirable if the thickness of the protective structure beneath the optical free-form structure were independent of the dimensions of the optical components used and, in particular, not specified by the gap between each coupling point and the lower side of the associated optical component. Furthermore, changes in ambient conditions should not have any or, at best, a negligible effect on the optical properties of the optical components, so that the long-term stability of the optical assembly is preferably ensured and maintained. means of solving the problem
[0014] This objective is achieved by an optical assembly having the features of an independent patent claim and a method for manufacturing the same. Advantageous improvements that may be implemented individually or in any desired combination are exemplified in the following description and dependent claims.
[0015] In a first aspect, the present invention relates to an optical assembly. In this case, the term "optical assembly" refers to a multi-component device comprising a plurality of elements interacting in such a manner configured to process optical radiation. The optical radiation used for this purpose may, in principle, comprise any type of optical radiation having a wavelength in the range of the optical spectrum or adjacent spectral regions. The visible light optical spectrum has wavelengths from 380 nm to 780 nm, but the infrared spectral range includes wavelengths from 780 nm to 1 mm, particularly 780 nm to 3 µm, 15 (near-infrared, "NIR") or 3 µm to 8 µm (mid-infrared, "MIR"), and ultraviolet spectral range wavelengths from 1 nm to 400 nm, preferably 100 nm to 400 nm, particularly 400 nm to 315 nm ("UV-A"), 315 nm to 280 nm ("UV-B") or 280 nm to 100 nm ("UV-C"). Wavelengths from 500 nm to 2000 nm are particularly preferred.
[0016] The optical assembly is:
[0017] - As at least one component carrier, the component carrier has a reference plane, at least one component carrier;
[0018] - At least two optical components attached to a component carrier, wherein each optical component has at least one optical coupling point, and for each optical component, in each case, an assembly plane is established that contacts the optical component and is parallel to a reference plane on a side facing the component carrier;
[0019] - At least one optical free-form structure connected to at least one of the optical coupling points, wherein the spatial region is formed by an assembly plane formed for the optical free-form structure and each optical component;
[0020] - At least one protective structure comprising at least one protective material surrounding an optical free-form structure in at least some area;
[0021] - At least one filling structure comprising at least one filling material, wherein the filling structure partially fills a space area, and the filling material has a relative change in mechanical dimensions smaller than that of a protective material within ambient conditions set for use of the assembly.
[0022] The optical assembly comprises at least one component carrier. The term “component carrier” here refers to a preferably planar substrate configured to accommodate at least one additional element, in particular at least two optical components and at least one filling structure. The component carrier may be a preferably transparent or opaque substrate comprising glass, silicon, at least one metal, in particular tungsten copper or Invar36, ceramic, in particular aluminum nitrite or aluminum oxide; however, in particular, as described in more detail below, in certain embodiments where at least one filling structure may be part of the component carrier, the use of other materials for the component carrier is possible.
[0023] A component carrier used for an optical assembly has a reference plane. In this case, the term "reference plane" refers to a virtual plane arranged parallel to the optical axis of the component carrier and at least two optical coupling points within the optical assembly, in addition to tolerance-related deviations, which will be described in more detail below. Particularly preferably, the position of the reference plane in the direction of the surface normal can be selected in such a way that the cross-sectional shape of the reference plane having the component carrier takes the maximum area. However, the selection of other reference planes for the component carrier is possible.
[0024] The optical assembly further comprises at least two optical components attached to a component carrier. In this case, the term “optical component” refers to an optical element configured to emit, receive, change, or transmit light. The optical components of this specification may comprise a single optical element or a plurality of optical elements. The optical element may be selected from optical elements for free-beam optical systems, particularly photoconductive single-mode or multi-mode fibers made of glass fibers, particularly organic or inorganic materials; semiconductor-based integrated optical chips, particularly lasers, optical amplifiers, photodiodes, super-light-emitting diodes, or silicon photonic chips; integrated optical chips based on semiconductor or dielectric materials, preferably glass, silicon dioxide, silicon nitride, or polymers; optical printed circuit boards; or optical elements for free-beam optical systems, particularly lenses, beam splitters, insulators, thin-film filters, mirrors, or diffraction gratings. Other types of optical components, particularly filters, power dividers, or electro-optical modulators, may be considered.
[0025] Each optical component has at least one optical coupling point. The term "optical coupling point" refers to a subregion of the optical component to be connected where light can be coupled into the optical component or light can be emitted from the optical component. For example, in simple optical components such as optical fibers or edge-emitting integrated optical chips, the optical coupling point may also be referred to as a "facet" or "waveguide facet." In photodiodes, the optical coupling point may be identical to the so-called "active surface" of the pn junction used for detection, where incident light within this active surface causes the generation of an electrical signal. In lasers, this may be an emitting surface on the edge or surface. More complex embodiments of the optical coupling point may be designed as a grating coupler, as a so-called "inverse taper," or as an etched micromirror. However, other types of optical coupling points are also possible.
[0026] For each optical component of the optical assembly, in addition to tolerance-related deviations, an assembly plane is formed for each optical component that contacts the optical component on a side facing the component carrier and is aligned parallel to a reference plane. The term "assembly plane" refers to a virtual surface on the component carrier where the assembly of the corresponding optical element is performed. In this case, the assembly of the optical element on the component carrier may be performed in such a manner that direct contact of the optical element on the component carrier occurs. Alternatively, the assembly of the optical element on the component carrier may be performed in such a manner that a gap is maintained between the optical element and the component carrier, particularly using an adhesive bonding process or a soldering process, which may be advantageous for positioning the optical element on the component carrier. The gap between the optical element and the component carrier may preferably be set using an adhesive gap or a spacer. For details regarding the reference plane and the assembly plane, refer to the following description together with the drawings.
[0027] The optical assembly further comprises at least one optical free-form structure; wherein the term “optical free-form structure” refers to a structure that may have a surface curved in any manner in at least some area, within the scope of technical limitations regarding resolution and accuracy. Thus, the free-form structure differs from conventional structure geometries that can be manufactured particularly by planar microstructuring methods. These combinations of conventional planar microstructuring methods generally result in prismatic three-dimensional structure geometries, which each have a base surface and a top surface substantially parallel to the substrate surface, and are connected to each other by sidewalls that are identical or very similar in shape and are perpendicular to the substrate surface and are inclined, inwardly, or outwardly curved, depending on the respective etching or deposition process. In contrast, the optical free-form structure is not subject to these limitations or to the same extent, and as a result, it is possible to provide a waveguide-based optical coupling element having a non-planar structure in which the centerline of the waveguide forming the coupling element does not need to lie in a common plane or mutually parallel planes. In a preferred embodiment, the optical free-form structure may comprise a photonic wire bond or a micro-optical structure, preferably a printed 3D microlens; however, other optical free-form structures are also possible. In particular, the optical free-form structure may be manufactured using an additive nanofabrication process, particularly preferably using 2-photon polymerization.
[0028] In the optical assembly, at least one optical free-form structure is connected to at least one of the optical coupling points. The term “connected” here means that the optical free-form structure has a fixed mechanical relationship with the optical coupling point and that light from the optical coupling point can interact with the free-form structure. However, for this purpose, the connected free-form structure does not need to be in direct mechanical contact with the optical coupling point. In a particularly preferred embodiment, exactly one optical free-form structure, particularly a photon wire bond, may serve to provide an optical connection between two optical coupling points spaced apart from each other. In particular, in this embodiment, the lateral spacing between the two optical coupling points may be 10 μm to 10 mm, preferably 20 μm to 1 mm, and particularly preferably 80 μm to 500 μm. In an alternative embodiment, exactly one optical free-form structure, in particular a printed 3D microlens, can be connected to exactly one of the optical coupling points so that optical radiation is guided from the first optical coupling point to the second optical coupling point of the second optical component. However, a number of additional embodiments are possible.
[0029] According to the present invention, a spatial region is established on one side by an optical free-form structure and on the other side by an assembly plane established for each optical component. In this case, the term "spatial region" refers to a volume formed by at least two boundary surfaces. Where it is possible to establish more than one assembly plane for an optical component, the assembly plane established for the relevant optical component is preferably used with a minimum distance from the free-form structure. The term "minimum distance" here refers to a connection path between two points that is shorter than any other connection path between two points. In this preferred embodiment, any connection path between any point on the optical free-form structure and each nearest point on the component carrier extends through the established spatial region.
[0030] The optical assembly further comprises at least one protective structure that, preferably, completely surrounds the optical free-form structure in at least some regions. Here, the term "protective structure" refers to a volume filled with a protective material and configured to stabilize the optical free-form structure in such a way that the optical assembly can operate over a long period under a wide range of ambient conditions. Additionally, the protective structure may also be used for additional purposes. In particular, where the optical free-form structure comprises a photon wire bond, the protective material may further be configured to provide a desired optical refractive index so that an optical waveguide can be formed from the photon wire bond as a waveguide core and the protective structure surrounding the photon wire bond can be formed as a cladding. Other possibilities are considered.
[0031] The protective material included in the protective structure may be selected from a number of materials. In one embodiment in which the optical free-form structure comprises at least one polymer, suitable for this purpose are, in particular, low-refractive-index polymers from the group of acrylates or epoxides, polymers that can be fluorinated, and polymers that may have polysiloxane components; however, other materials may be used. The protective material may preferably have an optical refractive index of 1 to 1.8, more preferably 1.2 to 1.5, and particularly 1.3 to 1.47. The difference in optical refractive index between the material of the optical free-form structure and the protective material may preferably be 0.02 to 1, particularly preferably 0.05 to 0.5, and particularly 0.1 to 0.3. The protective material may preferably be selected to have the lowest possible absorption rate at the operating wavelength of the optical free-form structure. The material absorption rate of the cladding material is up to 10 dB / mm, up to 5 dB / mm, up to 2 dB / mm, up to 2 dB / mm, up to 1 dB / mm, up to 0.5 dB / mm, within a wavelength range of 250 nm to 5000 nm, preferably 400 nm to 2500 nm, particularly preferably 530 nm to 2300 nm, and particularly up to 2 dB / mm, 1 dB / mm, or 0.5 dB / mm.
[0032] The above-described objective of the present invention is achieved particularly by at least one filling structure also enclosed by an optical assembly. The at least one filling structure at least partially fills a spatial region defined on one side by an optical free-form structure and on the other side by an assembly plane established for each optical component. In this case, a spatial region including all connection paths between any point of the optical free-form structure and each nearest point on each assembly plane is particularly preferred. The term “at least partially filling” refers herein to the presence of a filling structure within a volume, which is present completely or partially within the volume. In a particularly preferred embodiment, the spatial region may be filled with a filling material below the optical coupling point up to a height of less than 200 μm, particularly preferably less than 100 μm.
[0033] The use of the filler structure proposed herein makes it possible to reduce the influence of relative changes in the mechanical dimensions of the protective structure on the additional mechanical and / or optical properties, particularly of the optical free-form structure. The term "relative" here takes into account that changes in the mechanical dimensions of the structure also depend on the properties of the material of the structure. Accordingly, it is established that the filler material has a smaller change in mechanical dimensions than the protective material in a direction perpendicular to either the reference plane or the assembly plane. This corresponds to the same effect as when the protective material and the filler material are replaced together by a common material corresponding to the average value between the protective material and the filler material, with changes in their mechanical dimensions along with changes in ambient conditions.
[0034] The filling material surrounded by the filling structure may preferably be selected to have a smaller deviation in relative mechanical dimensions than the protective structure for the optical free-form structure within the ambient conditions set for the use of the optical assembly. The term “ambient conditions” here refers to external parameters acting on the optical assembly, particularly on the optical free-form structure. These include, in particular, temperature, ambient pressure, or vibration applied to the optical assembly from the outside. Despite changes in temperature, ambient pressure, or the occurrence of vibration, the use of the filling structure has the effect of preventing significant changes in the optical properties of the optical assembly, such that changes in the relative positions of the optical components, the optical free-form structure, and the protective structure for the optical free-form structure relative to each other are very small. Changes in ambient conditions typically expected in the optical assembly presented herein may include temperature changes of -40°C to +85°C or -60°C to +125°C, vibrations of the optical assembly at 10 Hz to 2 kHz with an acceleration of up to 20 g, and mechanical shocks with an acceleration of up to 500 g within milliseconds; Changes across different ranges can be considered.
[0035] In a particularly preferred embodiment, the filler material may have a low coefficient of thermal expansion compared to the coefficient of thermal expansion of the protective material. The term "low coefficient of thermal expansion" in this case is up to 100.10 -6 / K, preferably maximum 50·10 -6 / K, particularly preferably up to 20·10 -6 / K, especially up to 10·10 -6It includes a coefficient of / K. Preferably, the combination of the filler material and the protective material has an average coefficient of thermal expansion that is at least less than 2 times the coefficient of thermal expansion of the protective material alone. In certain embodiments, the coefficient of thermal expansion of the filler material may differ from the coefficient of thermal expansion of the material of each optical component and / or component carrier by up to 80%, preferably up to 40%, and particularly preferably up to 20%.
[0036] Materials having a low coefficient of thermal expansion are preferably suitable for the material of the fill structure. These include, in particular, tungsten copper or Invar36, silicon, ceramics, glass, UV-curing polymers or two-component adhesives; however, the use of at least one other fill material is possible.
[0037] In certain embodiments, the protective material may be an optically transparent material. In this embodiment, the optical refractive index of the filler material may preferably correspond to the optical refractive index of the protective material within a difference of 0.25.
[0038] The fill structure may preferably represent a standalone fill structure; in certain embodiments, it may be part of one of the optical components or component carriers. Preferably, the fill structure may therefore be a material additionally integrated within the assembly. In a particularly preferred embodiment, the fill structure may comprise a fill element made of a solid fill material integrated within a space region. Alternatively, the fill structure may comprise a material cured in the space region. In a particularly preferred alternative embodiment, the fill structure may be fixedly or releaseably connected to the component carrier or may be part of the component carrier, and the component carrier and the fill structure may preferably have the same material, namely the fill material. In a particularly preferred alternative embodiment, the fill structure may be fixedly or releaseably connected to at least one of the optical components or may be part of at least one of the optical components. In certain embodiments, the fill structure may serve as a mechanical stop for positioning the optical component.
[0039] In another aspect, the present invention relates to a method for manufacturing an optical assembly, particularly an optical assembly described in more detail above or below. The present method comprises the following method steps, and one or more, particularly consecutive, method steps may also be performed at least partially simultaneously: the method steps are:
[0040] a) providing at least one component carrier having a reference plane;
[0041] b) a step of attaching at least two optical components, each having at least one optical coupling point, to a component carrier, wherein, as a result, for each optical component, in each case, an assembly plane is established that contacts the optical component and is parallel to a reference plane on a side facing the component carrier;
[0042] c) a step of connecting at least one optical free-form structure to at least one of optical coupling points, wherein the at least one optical free-form structure is surrounded in at least a portion of the area by at least one protective structure comprising at least one protective material, and the spatial area is set by an assembly plane set for the optical free-form structure and each optical component;
[0043] d) a step of partially filling a space area using at least one filling structure composed of at least one filling material, wherein, under ambient conditions set for use of the assembly, the filling material has a relative change in mechanical dimensions smaller than that of the protective material.
[0044] In a particularly preferred embodiment, method step d) may be performed immediately after method step a), immediately after method step b), or simultaneously with method step b); however, different order of the method steps is possible.
[0045] According to method step a), a step of providing at least one component carrier, in particular at least one of the component carriers described in more detail above or below, is performed. As already described above, the component carrier has a reference plane.
[0046] According to method step b), the step of attaching at least one optical component, each having at least two optical coupling points as described above or below in more detail, to a component carrier is performed. As a result, an assembly plane is set for each optical component, and this assembly plane is arranged parallel to a reference plane and contacts the optical component on a side facing the component carrier.
[0047] According to method step c), as described in more detail above or below, a step of connecting at least one optical free-form structure to at least one of the optical coupling points is performed, and a spatial region is established by the optical free-form structure, the component carrier, and the optical component. In the process, the spatial region is established by an assembly plane established on one side by the optical free-form structure and on the other side for each optical component. In particular, the optical free-form structure may be manufactured using a stacked nanofabrication method, particularly preferably using 2-photon polymerization; however, other methods may be used.
[0048] In method step d), at least partial filling, preferably incomplete filling, of the space region is performed using at least one filling structure composed of at least one filling material. In a preferred embodiment, to at least partially fill the space region,
[0049] - A standalone filling structure, in particular, a fixed filling element can be integrated within a spatial area;
[0050] - A precursor structure of a charge element can be integrated into a spatial region, and in particular, can be processed to form a charge element by applying heat to the precursor structure;
[0051] - An optical component that already contains a charging element or to which a charging element is attached can be applied to a component carrier in such a manner that the resulting charging element enters a subsequent spatial region;
[0052] - At least one component carrier that already contains a charging element or to which a charging element is attached may be provided, and an optical element may be applied to the component carrier in such a manner that the charging element enters a subsequent spatial region as a result.
[0053] According to the present invention, for this purpose, the filling material used is one having a relative change in mechanical dimensions smaller than that of the protective material within the ambient conditions set for the use of the assembly.
[0054] For further details regarding the method, refer to the description of the optical assembly according to the present invention.
[0055] Advantages of the present invention
[0056] The optical assembly of the present invention has a number of advantages compared to optical assemblies known from the prior art. In the provided optical assembly, despite ambient conditions, particularly preferably ±260 K, more preferably ±80 K, or changes in ambient pressure, or the occurrence of vibration, the change in the relative position of the optical component, the optical free-form structure, and the protective structure for the optical free-form structure is very small, so that no significant change in the optical properties of the optical assembly occurs. The change in optical loss of the optical free-form structure is preferably up to 2 dB, particularly preferably up to 0.5 dB when typical variations in ambient conditions occur, particularly a change in temperature of ±80 K. In the case of a photon wire bond or a printed 3D microlens, the change in the optical free-form structure resulting from the local relative movement of the protective structure with respect to the position of the coupling point on the optical component is preferably up to 20 µm, particularly preferably up to 6 µm, particularly up to 2 µm, and the smaller the movement of the protective structure and thus the photon wire bond, the smaller the change in optical loss is typically.
[0057] The optical assembly is particularly suitable for industrial applications because individual processing steps are not required for the optical components, but standardized, commercially available optical components can be used instead. In this case, the thickness of the protective structure beneath the optical free-form structure is independent of the dimensions of the optical components used, whereas the optical free-form structure is not pre-formed by the distance of each coupling point, particularly from the lower side of the associated optical components. Furthermore, changes in ambient conditions should not have any or, at best, a negligible effect on the optical properties of the optical components, thereby ensuring and maintaining the desired long-term stability of the optical assembly.
[0058] The terms “having,” “having,” “including,” or “possessing,” or any grammatical variations thereof, are used herein in a non-exclusive manner. Accordingly, these terms may relate to situations in which, in addition to the features introduced by these terms, other features are absent, or situations in which one or more other features are present. For example, the expressions “A has B,” “A has B,” “A includes B,” or “A possesses B” may refer to situations in which no other element is present in A other than B (i.e., situations in which A consists only of B), and situations in which, in addition to B, one or more other elements, such as elements C, elements C and D, or even other elements, are present in A.
[0059] Furthermore, it is noted that the terms “at least one” and “one or more” and their grammatical modifications, when used in relation to one or more elements or features and intended to express that the elements or features may be provided one or more than once, are typically used only once, for example, when the feature or element is first introduced. When the feature or element is mentioned again thereafter, without limiting the possibility that the feature or element may be provided one or more than once, the corresponding terms “at least one” or “one or more” are typically no longer used.
[0060] Furthermore, the terms “preferred,” “preferably,” “particularly,” “for example,” or similar terms are used herein in relation to optional features, and alternative embodiments are not limited as a result thereof. Accordingly, the features introduced by these terms are optional features, and the scope of protection of the claims, particularly independent claims, is not intended to be limited by these features. Accordingly, the invention may also be implemented using other embodiments, as will be apparent to a person skilled in the art. Similarly, features introduced “in an embodiment of the invention” or “in an exemplary embodiment of the invention” are understood to be optional features, but this is not intended to limit alternative embodiments or the scope of protection of independent claims. Furthermore, these introductory expressions are intended to leave open all possibilities of combining the features introduced thereby with other features, whether optional or non-optional. Brief explanation of the drawing
[0061] Further details and features of the present invention are derived from the following description of preferred exemplary embodiments, in particular together with the dependent claims. In this case, each feature may be realized individually or in combination with one another. The present invention is not limited to exemplary embodiments. Exemplary embodiments are schematically illustrated in the following drawings. Herein, the same reference numerals in the drawings indicate elements that are identical or functionally identical in terms of their function or are equivalent to one another. In the drawings: FIGS. 1 to 4 each illustrate schematic diagrams of preferred embodiments of an optical assembly according to the present invention. FIG. 5 illustrates a schematic diagram of a preferred embodiment of a method for manufacturing an optical assembly according to the present invention. Specific details for implementing the invention
[0062] FIG. 1 illustrates a schematic diagram of a preferred embodiment of an optical assembly (10) according to the present invention, comprising a first optical component (30) and a second optical component (40) which can preferably be implemented in the form of a planar optical wave circuit (PLC), a laser, a photodetector, or a glass fiber mounted on a submount. The optical components (30, 40) preferably comprise an optical material (31, 41) which can be selected from silicon, silicon nitride, glass, a polymer, or indium phosphide; however, the use of other optical materials is possible. Each of the two optical components (30, 40) has at least one optical coupling point (50, 55). The optical coupling points (50, 55) of the two optical components (30, 40) are arranged relative to each other in such a manner that they can be connected using an optical free-form structure (200).
[0063] The optical assembly (10) schematically illustrated in FIG. 1 further comprises a common, preferably planar component carrier (20) to which two optical components (30, 40) are joined in such a manner, having mutual lateral spacing typically from 50 μm to 2000 μm, preferably from 100 μm to 500 μm. The component carrier (20) may preferably comprise a carrier material (21), preferably a metal, glass, or ceramic; however, other carrier materials may be used.
[0064] The optical assembly (10) schematically illustrated in FIG. 1 further includes an optical free-form structure (200) connecting optical coupling points (50, 55) each surrounded by two optical components (30, 40). The free-form structure (200) illustrated in FIG. 1 represents a preferred embodiment in the form of a photon wire bond (205).
[0065] As can also be seen from FIG. 1, the space region (150) can be set using a component height (140) having a value (d140) of typically 100 μm to 2000 μm and using a lateral spacing between the optical components (30, 40). The space region (150) is positioned between the assembly plane (110, 120) associated with each optical component (30, 40) and the free-form structure (200). According to the present invention, it is proposed that the space region (150) be at least partially filled with a filling structure (210). In a particularly preferred embodiment, starting from the upper edge of the component carrier (20), the space region (150) can be filled with a filling material (211) up to a height of less than 200 μm, particularly preferably less than 100 μm, below the optical coupling point (50, 55). Preferably, the assembly planes (110, 120) set for each optical component (30, 40) are set at a minimum interval having a value (d160 or d165) from the free-form structure (200). As a result, all connection paths (160, 165) extend through the spatial region (150) between the respective nearest point (160a, 165a) on each assembly plane (110, 120) and any point (160b, 165b) on the optical free-form structure (200).
[0066] According to the present invention, the filling structure (210) may be incorporated within the spatial region (150) before or after the manufacture of the free-form structure (200); however, particularly preferably, before the incorporation of a protective structure (250) comprising at least one protective material (251). Preferably, the minimum spacing between the optical free-form structure (200) and the filling structure (210) is less than 100 times the diameter of the optical free-form structure (200) measured perpendicular to the direction of local propagation of light.
[0067] The filling material (211) is preferably:
[0068] - Photo-curable materials, especially UV-curable materials;
[0069] - Thermosetting materials;
[0070] - Materials that harden at room temperature using moisture; or
[0071] - It may be selected from two-component materials having a low coefficient of thermal expansion according to the definition given above, but,
[0072] Materials other than the filling material (211) may be used. An exemplary material is 20·10 -6 "Optocast 3410" or 12·10, which is a silica-filled epoxy having a coefficient of thermal expansion of less than / K -6 It is “EP42HT-2LTE” by MasterBond having a coefficient of thermal expansion of less than / K. Other materials, particularly “Glassomers,” are also suitable as filler materials. When these materials are used, high fluidity and subsequent curing can simplify integration into the spatial region (150) between the optical components (30, 40).
[0073] FIG. 2 illustrates a schematic diagram of another preferred embodiment of an optical assembly (10) according to the present invention. In this embodiment, the assembly (10) comprises two optical components (30, 40) arranged on a common component carrier (20) in such a manner that a lateral spacing is maintained between the two components (30, 40) to connect the associated coupling points (50, 55) using an optical free-form structure (200) as described above. In this embodiment, the coupling points (50, 55) as well as the free-form structure (200) are arranged only in the upper region of the optical components (30, 40), so that the space region (150) is partially filled with a filling element (212) composed of a solid filling material (211) having a low coefficient of thermal expansion. The integration of the filling element (212) is preferably performed before the manufacture of the optical free-form structure (200) and before the application of the associated protective structure (250). The filling element (212) may be selected from a thin element composed of glass, silicon, ceramic, or metal, which at least partially fills the space area (150). A preferred filling material (211) for the filling element (212) is 3·10 -6 Float glass having a coefficient of thermal expansion of / K, 4.2·10 -6 Silicon with / K, 0.6·10 -6 Quartz glass having / K, 8·10 -6 WCu or 2·10 with / K -6 It includes Invar36 with / K, but it is possible to use other filler materials with a low coefficient of thermal expansion.
[0074] For this purpose, the filling element (212) may preferably be adjacent to or connected to a component holder (20) on one or more optical components (30, 40) using an adhesive element (not shown). The filling element may be directly adjacent to one or more optical components (30, 40), and the connection may also include one or more butt gaps or adhesive gaps. In particular, for practical reasons for manufacturing the optical assembly (10), it may be advantageous to first fasten the filling element (212) to the optical component (30), preferably a glass fiber, then fasten the optical component (30) together with the filling element (212) to the component carrier (20), and then connect a second optical element (40) thereto. However, numerous other variations of this procedure are possible.
[0075] FIG. 3 illustrates a schematic diagram of another preferred embodiment of an optical assembly (10) according to the present invention. In this exemplary embodiment, the combined component carrier and filling element (22) is implemented in such a way that an edge is formed between the optical components (30, 40), and this edge forms a lateral gap between the optical components (30, 40) and serves as a partial filling element (212) for the spatial region (150) between the optical components (30, 40), the free-form structure (200), and the assembly planes (110, 120) of the optical components (30, 40). Here also, the carrier material (211) of the combined component carrier and filling element (22) is preferably 200·10 -6 Less than / K, particularly preferably 100·10 -6 Less than / K, very particularly preferably 50·10 -6 It has a low coefficient of thermal expansion of less than / K. Particularly suitable for forming the combined component carrier and filler element (22) is
[0076] - 8·10 -6Metals such as WCu having a coefficient of thermal expansion of / K;
[0077] - 2·10 -6 Invar36 having a thermal expansion coefficient of / K; or
[0078] - (Sintered) ceramics with a low coefficient of thermal expansion, such as AlN or Al2O3, but;
[0079] The use of materials other than the filling material (211) is also possible here.
[0080] FIG. 4 illustrates a schematic diagram of another preferred embodiment of an optical assembly (10) according to the present invention. The optical assembly (10) schematically illustrated in FIG. 4 comprises an optical free-form structure (200), which is implemented here as a micro-optical structure, particularly as a printed 3D microlens (206) attached to an optical coupling point (50). However, other types of free-form structures may be considered. Preferably, light can be guided from an optical coupling point (50) to another optical coupling point (55) by the free-form structure (200). Here, the optical free-form structure (200), which is in the form of a 3D microlens coupled to the optical coupling point (50), does not necessarily need to be mechanically connected to the coupling point; it may also be mechanically connected only to the optical component (30) or only to the filling structure (210).
[0081] FIG. 5 illustrates a schematic diagram of a preferred embodiment of a method (310) for manufacturing an optical assembly (10) according to the present invention, particularly described in one of the exemplary embodiments according to FIG. 1 to 4.
[0082] In the providing step (312) according to method step a), the step of providing a component carrier (20) is performed, and the component carrier (20) has a reference plane (100).
[0083] In the attachment step (314) according to method step b), a step of attaching a first optical component (30) having an optical coupling point (50) and a second optical component (40) having an optical coupling point (55) to a component carrier (20) is performed. As a result, a first assembly plane (110) is set for the first optical component (30), and this first assembly plane contacts the first optical component (30) on a side facing the component carrier (20) and is parallel to a reference plane (100). Likewise, a second assembly plane (120) is set for the second optical component (40), and this second assembly plane contacts the second optical component (40) on a side facing the component carrier (20) and is likewise parallel to a reference plane (100).
[0084] In the filling step (316) according to method step d), at least partial filling, preferably incomplete filling, of the space area (150) is performed using at least one filling structure (210) composed of a filling material (211). In a preferred embodiment of the process (310) schematically illustrated in FIG. 5, process step d) is performed immediately after process step a) or simultaneously with process step b), but process steps in a different order (not illustrated) are possible. As described above, under ambient conditions set for the use of the assembly (10), the filling material (211) has a smaller relative change in mechanical dimensions than the protective material (251).
[0085] In the connection step (318) according to method step c), the step of connecting the optical free-form structure (200) to one or both optical coupling points (50, 55) is performed. In the process, the optical free-form structure (200) is preferably completely surrounded in at least some area by a protective structure (250) comprising a protective material (251). As a result, the spatial area (150) is set by assembly planes (110, 120) set for the optical free-form structure (200) and each optical component (30, 40).
[0086] For further details regarding FIGS. 2 to 5, refer to the description in FIG. 1. Explanation of the symbols
[0087] 10: Optical assembly 20: Component Carrier 21: Carrier material 22: Combined component carrier and filling element 30, 40: Optical components 31, 41: Optical materials 50, 55: Optical coupling points 100: Reference plane 110, 120: Assembly plane 140: Component height 150: Spatial domain 160, 165: Connection path 160a, 165a: Nearest point 160b, 165b: arbitrary points 200: Free-form structure 205: Photon wire bond 206: Printed 3D microlenses 210: Charging structure 211: Filling material 212: Charging element 250: Protective structure 251: Protective material 310: Method for manufacturing an optical assembly 312: Provisioning step 314: Attachment step 316: Charging stage 318: Connection Step
Claims
Claim 1 An optical assembly (10), comprising: at least one component carrier (20), wherein the component carrier (20) has a reference plane (100); at least two optical components (30, 40) attached to the component carrier (20), wherein each optical component (30, 40) has at least one optical coupling point (50, 55), and for each optical component (30, 40), in each case, an assembly plane (110, 120) is set that contacts the optical component and is parallel to the reference plane (100) on a side facing the component carrier (20); and at least one optical free-form structure (200) connected to at least one of the optical coupling points (50, 55), wherein a spatial region (150) is set for the optical free-form structure (200) and each optical component (30, 40). An optical assembly (10), comprising: at least one optical free-form structure (200) formed by planes (110, 120); at least one protective structure (250) comprising at least one protective material (251) surrounding the optical free-form structure (200) in at least a portion of the area; and at least one filling structure (210) comprising at least one filling material (211), wherein the filling structure (210) at least partially fills the space area (150), and the filling material (211) has a relative change in mechanical dimensions smaller than that of the protective material (251) within ambient conditions set for use of the assembly (10). Claim 2 In claim 1, all connecting paths (160, 165) between any point (160b, 165b) on the optical free-form structure (200) and each nearest point (160a, 165a) on each assembly plane (110, 120) extend through a spatial region (150), an optical assembly (10). Claim 3 An optical assembly (10) according to claim 1 or 2, wherein the spatial region (150) is filled with a filling material (211) up to a height of less than 200 μm, particularly preferably less than 100 μm, below the optical coupling point (50, 55). Claim 4 An optical assembly (10) according to any one of claims 1 to 3, wherein the minimum gap between the optical free-form structure (200) and the filling structure (210) is less than 100 times the diameter of the optical free-form structure (200). Claim 5 In any one of paragraphs 1 to 4, the filling material (211) is up to 100·10 -6 Optical assembly (10) having a thermal expansion coefficient of / K. Claim 6 An optical assembly (10) according to any one of claims 1 to 5, wherein the combination of the filling material (211) and the protective material (251) has an average thermal expansion coefficient less than at least 2 times the thermal expansion coefficient of the protective material (251) alone. Claim 7 An optical assembly (10) according to any one of claims 1 to 6, wherein the coefficient of thermal expansion of the filling material (211) in the space region (150) differs from the coefficient of thermal expansion of the material of each optical component (30, 40) by up to 50%. Claim 8 An optical assembly (10) according to any one of claims 1 to 7, wherein the filling structure (210) comprises a material cured in a space region (150); and a filling element (212) made of a solid filling material (211) and integrated within the space region (150). Claim 9 An optical assembly (10), wherein, in any one of claims 1 to 8, the filling structure (210) is a part of the component carrier (20); and the component carrier (20) is connected to the component carrier (20) in a fixed or releaseable manner, and the component carrier (20) preferably also comprises a filling material (211). Claim 10 In any one of claims 1 to 9, the filling structure (210) is fixedly or releaseably connected to at least one of the optical components (30, 40); and the optical assembly (10) is a part of at least one of the optical components (30, 40). Claim 11 In any one of claims 1 to 10, the filling structure (210) serves as a mechanical stop for positioning optical components (30, 40), an optical assembly (10). Claim 12 An optical assembly (10) according to any one of claims 1 to 11, wherein the lateral spacing between two optical coupling points (50, 55) is 10 μm to 10 mm. Claim 13 In any one of claims 1 to 12, the optical free-form structure (200) comprises an optical assembly (10) including a photonic wire bond (205) or a micro-optical structure. Claim 14 An optical assembly (10) in any one of claims 1 to 13, wherein the protective material (251) is an optically transparent material and the optical refractive index of the filling material (211) is lower than the optical refractive index of the protective material (251). Claim 15 In particular, a method (310) for manufacturing an optical assembly (10) according to any one of claims 1 to 14, wherein the method comprises: a) providing at least one component carrier (20), wherein the component carrier (20) has a reference plane (100); b) attaching at least two optical components (30, 40), each having at least one optical coupling point (50, 55), to the component carrier (20), such that, as a result, for each optical component (30, 40), a single assembly plane (110, 120) is formed that contacts the optical component and is parallel to the reference plane (100) on a side facing the component carrier (20) in each case; c) connecting at least one optical free-form structure (200) to at least one of the optical coupling points (50, 55), wherein the at least one optical free-form structure (200) comprises at least one protective material (251). A method (310) comprising: a step of connecting, wherein the space area (150) is surrounded in at least a portion of the area by at least one protective structure (250), and the space area (150) is set by assembly planes (110, 120) set for the optical free-form structure (200) and each optical component (30, 40); and a step of filling, wherein the space area (150) is at least partially filled by using at least one filling structure (210) composed of at least one filling material (211), wherein, under ambient conditions set for the use of the assembly (10), the filling material (211) has a relative change in mechanical dimensions smaller than that of the protective material (251). Claim 16 In claim 15, the optical free-form structure (200) is manufactured using a stacked nanofabrication method, particularly preferably using 2-photon polymerization, method (310).