Optical assembly and method of manufacturing the same
Patent Information
- Application Number
- KR1020267027984
- 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 these 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 adapted directly 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. In a further 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] Furthermore, 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 aforementioned butt coupling 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 technology (TPP) using femtosecond lasers with resolution below the diffraction limit. The morphology of photon wire bonds can be adapted across different material platforms for components and / or waveguide dimensions of components, i.e., corresponding mode field profiles. Typical waveguide dimensions on optical chips that can be connected by 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, particularly when the trajectory of the photon wire bond includes bends, the photon wire bond must be dimensioned in such a way that it is substantially single-mode. For common dimensions, this requires cladding the photon wire bond with a cladding structure made of a selected cladding material that provides the desired optical refractive index so that the corresponding refractive index contrast is established with the photon wire bond material. Additionally, the cladding structure must stabilize the photon wire bond in such a way that the optical assembly can operate for extended periods under most diverse ambient conditions. Due to the dimensions of the photon wire bond, which have a width and thickness of several micrometers and a length of several hundred micrometers, it is a challenge to provide optical connections by 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. An optical assembly for optically connecting two or more optical components comprises a number of different materials having fundamentally different properties, ranging from the mechanical carrier and the material of the optical chip to the material of the photon wire bond and the cladding structure. Under changing ambient conditions, the different materials may change their properties, for example, their thermal expansion, differently.
[0006] US 2013 / 0223788 A1 discloses that free-form structures are embedded in a polymer material curable by UV or heat, such as, for example, CYTOP, a fluoropolymer with a refractive index of about 1.37, a durometer hardness Shore D 78, and a coefficient of linear expansion (CTE) of 74 ppm / K. By the curable polymer, the free-form structures are rigidly enclosed by the polymer; the polymer is localized around the optical coupling point. However, a CTE approximately 10 times greater than that of optical components made of silicon, InP, or glass results in strong relative displacement between the cladding material and the optical component under variable ambient conditions. Due to the high hardness of the cladding material, the embedded free-form structures generally follow this relative displacement, which can result in high optical loss, up to a complete loss of optical coupling, when the free-form structures are separated from the optical coupling point of the optical component.
[0007] The literature [Billah et al., Hybrid Integration of Silicon Photonics circuits and InP Lasers by Photonic Wire Bonding, Optica Vo. 5 (7), 2018, pages 876-883) suggests using index oil as a cladding material to establish a suitable refractive index contrast between the free-form structure and the cladding material. However, there is a problem here in that the oil dripping onto the coupling point may leak out of the region of optical coupling, which does not result in a stable assembly over a long period of time. The problem to be solved
[0008] 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.
[0009] The object of the present invention is to provide an optical assembly in which, despite changes in ambient conditions—particularly preferably a temperature of up to ±260 K, more preferably up to ±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 cladding 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.
[0010] The change in optical loss of an optical free-form structure used to optically 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 displacement of the cladding 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.
[0011] It would also be desirable that the optical properties of the optical connection be maintained at a constant level and that the cladding structure be maintained within the region of optical coupling of at least two optical components, and that it not melt or move over a relatively long period of time, and thus not contaminate other optical components located near the optical coupling point. 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 guaranteed and maintained. means of solving the problem
[0012] 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.
[0013] 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, include 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.
[0014] The optical assembly is:
[0015] - At least one component carrier;
[0016] - At least one optical component attached to a component carrier, wherein the optical component has at least one optical coupling point;
[0017] - At least one optical free-form structure connected to an optical coupling point;
[0018] - At least one cladding structure surrounding an optical free-form structure in at least some regions, wherein the cladding structure comprises at least one viscoelastic cladding material;
[0019] - As at least one boundary structure, the boundary structure and the optical component comprise at least one boundary structure forming at least a partial enclosure for the cladding structure, and
[0020] The cladding material has a storage modulus with a maximum value of 1000 kPa.
[0021] The optical assembly comprises at least one component carrier. As specified herein, the term “component carrier” 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 preferably be a 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, it is possible to use other materials for the component carrier.
[0022] The optical assembly further comprises at least one optical component 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 component 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.
[0023] At least one 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 a photodiode, 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 a laser, 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.
[0024] 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. Accordingly, 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 typically 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 design 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 by an additive nanofabrication process, particularly preferably by 2-photon polymerization.
[0025] 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” 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 fixed mechanical contact with the optical coupling point. In a particularly preferred design 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 such a design 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 design 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 directed from the first optical coupling point to the second optical coupling point of the second optical component. However, a number of additional design embodiments are possible.
[0026] The optical assembly further comprises at least one cladding structure that, preferably, completely surrounds the optical free-form structure in at least some regions. The term "cladding structure" here refers to a volume filled with a cladding 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. Furthermore, the cladding structure may also be used for additional purposes. In particular, where the optical free-form structure comprises a photon wire bond, the cladding 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 the waveguide core and the cladding structure surrounding the photon wire bond as the cladding. Other possibilities may be considered.
[0027] The cladding material included in the cladding structure may be selected from a number of materials. In one design embodiment in which the optical free-form structure comprises at least one polymer, suitable for this includes a particularly low-refractive-index polymer from the group of acrylates or epoxides, a polymer that can be fluorinated, a polymer that can have a polysiloxane component, or an oil; however, other materials may be used.
[0028] According to the present invention, the cladding material has a storage modulus having a maximum value of 1000 kPa. Here, the term "storage modulus" refers to energy stored within an object after a force is applied, and the application of the force can be dynamic or static. A portion of this energy can be obtained from the object again after the load is relieved by the force applied to the object.
[0029] In a particularly preferred design embodiment, the storage modulus may further be up to 1,000 times greater than the loss modulus of the cladding material. In this context, the term "loss modulus" refers to the additional portion of energy retained within an object after the force applied thereto has been relieved, particularly after it has been converted into heat by internal friction. Thus, the indication of the loss modulus refers to the proportion of viscosity of the material within the object. In a preferred design embodiment, the cladding material may have a non-negligible viscous fraction. This implies that the material possesses so-called "strain relief" properties, that is, stress can be reduced over time by external deformation of the cladding material.
[0030] In a preferred design embodiment, the storage modulus may have a maximum value of 500 kPa, particularly preferably 200 kPa, particularly 100 kPa, and the storage modulus of the cladding material may be greater than the loss modulus of the cladding material by up to 500 times, particularly preferably up to 200 times, particularly up to 100 times. In another preferred design embodiment,
[0031] - The storage modulus may have a value of 0.1 kPa to 60 kPa, preferably 1 kPa to 30 kPa, more preferably 2 kPa to 15 kPa;
[0032] - The loss modulus may have a value of 0.01 kPa to 30 kPa, preferably 0.05 kPa to 10 kPa, and more preferably 0.1 kPa to 5 kPa.
[0033] In a preferred design embodiment, the value of the storage modulus may be lower than the value of the loss modulus of the cladding material, so that the behavior of the cladding material corresponds to the behavior of the liquid.
[0034] In a preferred design embodiment, the value for the storage modulus may be set in such a way that, within the ambient conditions set for the use of the optical assembly, the cladding material substantially maintains its spatial position and shape, and furthermore, surrounds at least a free-form structure in at least some area. The term “ambient conditions” refers herein 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 cladding structure relative to one another 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, vibration of the optical assembly at 10 Hz to 2 kHz with an acceleration of up to 20 g, and mechanical shock with an acceleration of up to 500 g within milliseconds; Changes across different ranges can be considered.
[0035] Furthermore, in a preferred design embodiment, the value of the shear modulus of the cladding material may be set in such a way that, in the local relative movement between the cladding structure and the free-form structure within the ambient conditions defined for the use of the assembly, the shear stress of the cladding material surrounding the free-form structure is very low, thereby allowing the free-form structure to substantially maintain its spatial position and shape. The term "shear modulus" here refers to a parameter of the material indicating the linear elastic deformation of an object containing this material as a result of shear stress or shear force, and the deformation may occur dynamically or statically. Significant deformation or displacement exists within the optical assembly when the optical coupling by the free-form structure between the two components changes by at least 1.5 dB, preferably by at least 1.0 dB, and particularly by at least 0.5 dB. Minute deformation or displacement of the free-form structure that does not affect the optical coupling loss may be assumed to be relieved again when returning to the original ambient conditions.
[0036] Preferably, the cladding material may have an optical refractive index of 1 to 1.8, particularly 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 cladding material may preferably be 0.02 to 1, particularly preferably 0.05 to 0.5, and particularly 0.07 to 0.2. In certain design embodiments, the cladding material may be an optically transparent material. To this end, the cladding material may preferably be selected in such a manner that an ideally low absorption rate occurs 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.
[0037] The optical assembly further comprises at least one boundary structure forming at least a partial enclosure for a cladding structure together with an optical component and optionally additional elements, in particular a component carrier. The term “boundary structure” refers to a volume filled with a boundary material and designed to stabilize the cladding structure in such a way that it is possible to operate the optical assembly, in particular at least one optical free-form structure included in the optical assembly, over a long period of time under most various ambient conditions, either alone or with the additional use of at least one other structure. In a preferred design embodiment, the boundary structure may form at least a partial enclosure for a cladding structure together with at least one optical component and at least one component carrier.
[0038] The boundary material may preferably be selected from at least one crosslinkable polymer based on an epoxide, acrylate, or silicone or a combination thereof. In particular, the boundary structure may also be configured to form both the lateral boundary (dam) and the upper boundary (encapsulation) of the optical assembly (10). Crosslinking of at least one polymer may preferably be carried out by UV exposure, thermal exposure, moisture at room temperature, and / or a two-component reaction.
[0039] In a preferred design embodiment, the boundary structure may be constructed in such a way that, in the event of a change in the volume of the cladding structure, the pressure inside the cladding structure remains substantially constant. Here, the term "substantially constant" indicates that if the boundary structure has an elastic design, the pressure may increase by a small amount, and in particular, if a change in the volume of the cladding structure, for example as a result of thermal expansion, leads to an increase in pressure within the volume enclosed by the boundary structure; rather, the boundary structure itself may deform due to its elastic configuration. To this end, in particular, at least a portion of the boundary structure may be formed by a thin layer of boundary material, preferably 1 mm or less, particularly preferably 0.5 mm or less, particularly 0.1 mm or less, and the boundary material may have a hardness preferably Shore A 80 or less, more preferably Shore A 50 or less. Preferably, the boundary material may have a higher storage modulus than the cladding material.
[0040] In another preferred design embodiment, the boundary structure may be in the form of a cover, which may particularly include thin glass or a thin covering membrane. In this case, the cover may be adhesively bonded to at least one optical component and, more preferably, to at least one additional part of the boundary structure. The elasticity of the boundary structure may also be adjusted through the material and thickness of the cover. In a specific design embodiment, the boundary structure may have at least one adhesive joint or an additionally coated structure.
[0041] In an alternative design embodiment, the boundary structure may include an outer region referred to as the "shell" of the cladding structure, and an inner region referred to as the "core" of the cladding structure comprises a viscoelastic cladding material. The shell may have a thickness of up to 100 μm, particularly preferably up to 50 μm. In this case, the core may be in the form of a liquid material, while the "shell" may comprise a solid material.
[0042] In a preferred design embodiment, the optical assembly may additionally have at least one opening within the boundary structure. In this case, the size of the opening may be selected so that the viscoelastic cladding material cannot leak out in the event of a change in volume but is retained within the volume enclosed by surface tension. As a result, the liquid cladding material can be retained in place, while, in the event of a change in volume, particularly as a result of thermal expansion, any pressure change that could adversely affect the optical assembly, particularly the free-form structure, cannot occur simultaneously within the boundary structure. In this case, the at least one opening in the boundary structure may preferably have a lateral range of 200 μm or less, particularly preferably 100 μm or less, and particularly 50 μm or less.
[0043] 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:
[0044] a) providing at least one component carrier;
[0045] b) attaching at least one optical component having at least one optical coupling point to a component carrier;
[0046] c) connecting at least one optical free-form structure to at least one optical coupling point;
[0047] d) a step of surrounding an optical free-form structure with at least one cladding structure in at least a portion of the area, wherein the cladding structure comprises at least one viscoelastic cladding material;
[0048] e) a step of creating at least one boundary structure in such a manner that the boundary structure and the optical component form at least a partial enclosure for the cladding structure, and
[0049] The cladding material is selected in this manner to have a storage modulus with a maximum value of 1000 kPa.
[0050] 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.
[0051] According to method step b), a step of attaching at least one optical component having at least one optical coupling point to a component carrier is performed, as described above or below in more detail.
[0052] According to method step c), a step of connecting at least one optical free-form structure to at least one optical coupling point is performed, as described above or below in more detail. In particular, the optical free-form structure may be prepared by a stacked nanofabrication method, particularly preferably by 2-photon polymerization; however, other methods may be used.
[0053] According to method step d), the step of surrounding an optical free-form structure with at least one cladding structure in at least a portion of the area is performed, wherein the cladding structure comprises at least one viscoelastic cladding material, and the cladding material is selected in this manner having a storage modulus having a maximum value of 1000 kPa. Particularly preferably, the storage modulus may be up to 1000 times greater than the loss modulus of the cladding material.
[0054] According to method step e), the step of creating at least one boundary structure occurs in such a way that the boundary structure and the optical component form at least a partial enclosure for the cladding structure. In this process, the boundary structure may preferably be created by applying the boundary structure to the cladding structure. In this case, the boundary structure may also be applied at least partially prior to method step d). In an alternative design embodiment, the step of creating the boundary structure may be performed by processing an outer region referred to as the "shell" of the cladding structure, while the viscoelastic cladding material is retained in an inner region referred to as the "core" of the cladding structure. The processing may preferably be performed by UV exposure, thermal exposure, moisture at room temperature, and / or a two-component reaction. As a result of the processing, a shell is formed having a thickness of up to 100 μm, particularly preferably up to 50 μm.
[0055] For further details regarding the method, refer to the description of the optical assembly according to the present invention and exemplary embodiments.
[0056] Advantages of the present invention
[0057] The present optical assembly has several advantages over 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 photon wire bonds or printed 3D microlenses, 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.
[0058] The optical assembly further enables the optical properties of the optical connection to be maintained constant and the cladding structure to be maintained within the region of optical coupling of at least two optical components, and not to melt or move over a relatively long period of time, thus not contaminating other optical components located near the optical coupling point. 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.
[0059] 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 includes B,” or “A possesses B” may refer to situations in which, other than B, no other element is present in A (i.e., situations in which A consists only of B), and situations in which, in addition to B, one or more other elements, e.g., elements C, C and D, or even other elements, are present in A.
[0060] Furthermore, it is noted that the terms “at least one” and “one or multiple” and their grammatical variations are used only once, for example, when the feature or element is first introduced, when they are used in relation to one or multiple elements or features and are intended to express that the element or feature may be provided in a single or multiple manner. When the feature or element is mentioned again thereafter, without limiting the possibility that the feature or element may be provided once or multiple times, the corresponding terms “at least one” or “one or multiple” are generally no longer used.
[0061] 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 by them. 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 present invention may also be carried out using other design embodiments, as will be apparent to a person skilled in the art. Similarly, features introduced “in an embodiment of the present invention” or “in an exemplary embodiment of the present invention” are understood to be optional features, but this is not intended to limit alternative design 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 by them with other features, whether optional or non-optional. Brief explanation of the drawing
[0062] 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 implemented 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 3 each illustrate schematic diagrams of preferred embodiments of an optical assembly according to the present invention. FIG. 4 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
[0063] FIG. 1 illustrates a schematic diagram of a preferred embodiment of an optical assembly (10) according to the present invention, which typically comprises a first optical component (30) and a second optical component (31). The optical components (30, 31) may preferably be selected from silicon photonic chips, particularly silicon-on-insulator (SOI) chips, lasers made of indium phosphide (InP), photonic chips based on silicon nitride or lithium niobate, or single-mode fibers. Furthermore, as can be derived from FIG. 1, the optical components (30, 31) are attached to a common component carrier (20), and the component carrier (20) may preferably comprise aluminum nitride or tungsten copper; however, the use of other materials for the component carrier (20) is possible. In certain embodiments (not illustrated), particularly when a laser made of InP is placed on an SOI chip, one optical component may simultaneously serve as a carrier for another optical component. Each of the two optical components (30, 31) has at least one optical coupling point (40, 41). The optical coupling points (40, 41) of the two optical components (30, 31) are arranged relative to each other in such a way that they can be connected by an optical free-form structure (50).
[0064] The optical assembly (10) further comprises an optical free-form structure (50) connecting optical coupling points (40, 41) that are each surrounded by two optical components (30, 31). The free-form structure (50), schematically illustrated in FIG. 1, comprises a material (60), particularly a polymer, manufactured by 3D lithography, particularly by two-photon polymerization. In this case, the free-form structure (50) does not need to be in direct mechanical contact with the optical coupling points (40, 41); instead, it is sufficient that light from the optical coupling points (40, 41) can interact with the free-form structure (50). As illustrated in FIG. 1, the free-form structure (50) can preferably be implemented as a photon wire bond. In an alternative embodiment according to FIG. 2, the free-form structure (50) can be implemented as a microlens that enables optical coupling.
[0065] In particular, to achieve an adapted refractive index contrast, according to the present invention, a free-form structure (50) is surrounded by a cladding structure (70) in at least some area, and the cladding structure (70) comprises at least one viscoelastic cladding material (80). The refractive index contrast between the free-form structure (50) and the cladding structure (70) can preferably take a value of 0.01 to 1.0, particularly preferably 0.05 to 0.2. For example, a photon wire bond as the free-form structure (50) can have a refractive index of 1.5, while the cladding material (80) takes a refractive index of 1.4. The cladding material (80) can be substantially transparent to light having a wavelength of preferably 190 nm to 10.7 µm, particularly preferably 400 nm to 2.5 µm, particularly 530 nm to 1.8 µm.
[0066] In a preferred embodiment, the cladding material (80) may be a liquid embodiment, preferably 1 cm 2 / s to 1,000,000 cm 2 / s, particularly preferably 100 cm 2 / s to 100,000 cm 2 / s, especially 1000 cm 2 / s to 50,000 cm 2 It can have a viscosity of / s. The viscoelastic cladding material may preferably be a so-called refractive index oil, for example, "Cargille Series A", a liquid based on a monomer mixture, a siloxane-based liquid, or a hydrocarbon-based oil.
[0067] In another embodiment, the cladding material (80) is not a liquid but rather a viscoelastic material, and the value for the shear modulus of the cladding material (80) is selected such that, in the local relative movement between the free-form structure (50) and the cladding structure (70) attached at least one coupling point (40, 41), the shear stress of the viscoelastic material surrounding the free-form structure (50) changes as a result of ambient conditions, particularly temperature changes, vibrations, or changes during the curing of the applied material, so that no significant deformation or displacement of the free-form structure (50) occurs. At the same time, the storage modulus of the cladding material (80) may be selected so as to be dimensionally stable, that is, not to melt under gravity and / or typical ambient conditions, particularly temperatures from -40°C to +85°C and / or vibration or impact tests of up to 500 g.
[0068] To this end, the cladding material (80) may preferably be implemented in the form of a gel-like material based on at least one epoxide, acrylate, or siloxane or a mixture thereof. The viscoelastic material may be applied in liquid form and may be crosslinked by UV exposure, thermal exposure, moisture at room temperature, or by a two-component reaction. The storage modulus of the crosslinked cladding material (80) may preferably be 0.1 kPa to 50 kPa, more preferably 1 kPa to 20 kPa, particularly 2 kPa to 10 kPa, while the loss modulus may preferably be 0.01 kPa to 20 kPa, particularly preferably 0.05 kPa to 5 kPa, particularly 0.1 kPa to 2 kPa. As a result, the free-form structure, which can preferably be implemented as a photon wire bond or an optical lens, may have a Shore D hardness of 50 to 80 or more and a shear modulus of > 50 MPa so as not to deform significantly in the case of thermal expansion.
[0069] In this case, the shear modulus of the cladding material (80) can preferably be selected such that, as a result of changing ambient conditions, in the case of a temperature change of preferably -40°C to +85°C, particularly preferably -60°C to 125°C, the shear stress of the cladding material (80) is very low so that no significant deformation or displacement of the free-form structure (50) occurs in the local relative movement between the cladding structure (70) and the free-form structure (50). Significant deformation or displacement exists when the optical coupling by the free-form structure (50) between the two components (30, 31) changes by at least 1.5 dB, particularly by at least 0.5 dB. As mentioned above, the minute deformation or displacement of the free-form structure that does not affect the optical coupling loss can be assumed to be relieved again when returning to the original ambient conditions.
[0070] In order to maintain the viscoelastic cladding material (80) in a suitable location around the free-form structure (50), in the embodiment according to FIG. 1, the cladding structure (70) is surrounded by a component carrier (20), two optical components (30, 31), and a boundary structure (90). To this end, the boundary structure (90) may preferably comprise a material (100) selected from at least one crosslinkable polymer. The polymer may preferably be based on an epoxide, an acrylate, or a silicone or a combination thereof. To this end, the boundary structure (90) may be configured to form both the lateral boundary (dam) and the upper boundary (encapsulation) of the optical assembly (10). Crosslinking of at least one polymer may preferably be carried out by UV illumination, thermal exposure, moisture at room temperature, and / or a two-component reaction.
[0071] For example, it may be particularly advantageous when the boundary structure (90) is elastic so that a change in the volume of the cladding structure (70) due to thermal expansion does not cause an increase in pressure within the volume enclosed by the boundary structure (90), but rather the boundary structure (90) itself may be deformed. This can be achieved particularly when at least a portion of the boundary structure is formed as a thin layer of the boundary material (100), preferably 1 mm or less, particularly preferably 0.5 mm or less, particularly 0.1 mm or less, and the boundary material may preferably have a Shore A hardness of 80 or less, more preferably Shore A hardness of 50 or less. Preferably, the boundary material (100) may have a higher storage modulus than the cladding material (80).
[0072] In another embodiment, the boundary structure (90) may be in the form of a cover made particularly of thin glass or a thin cover membrane, and the cover may be adhesively bonded to the optical components (30, 31) and preferably at least one additional part of the boundary structure (90). The elasticity of the boundary structure (90) may also be set through the material and thickness of the cover. Furthermore, the boundary structure (90) may also have an adhesive joint or an additionally applied structure.
[0073] As schematically illustrated in FIG. 1, the optical assembly (10) may include two optical components (30, 31) on a common component carrier (20), and the two optical components (30, 31) are optically connected to each other by a free-form structure (50). As described above, for this purpose, the free-form structure (50) is surrounded in at least some area by a cladding structure (70) composed of a viscoelastic cladding material (80), and the cladding structure (70) is held in place by at least one boundary structure (90).
[0074] FIG. 2 illustrates an alternative embodiment in which an optical assembly (10), in which a cladding structure (70) is completely bordered by two components (30, 31), a component carrier (20), and a boundary structure (90), additionally has at least one opening (not shown) within the boundary structure (90). In this case, the size of the opening may be selected so that the viscoelastic cladding material (80) cannot leak out in the event of a change in volume but is maintained within the volume enclosed by surface tension. As a result, the liquid cladding material (80) can be maintained in place, while, in the event of a change in volume, any pressure change that could have a negative effect on the optical assembly (10), particularly the free-form structure (50), cannot occur simultaneously within the boundary structure (90), especially as a result of thermal expansion. As mentioned above, at least one opening of the boundary structure may have a lateral range of preferably 200 μm or less in this case, particularly preferably 100 μm or less, and particularly 50 μm or less.
[0075] In the embodiment according to FIG. 1, the incompressible viscoelastic cladding material (80) is typically completely enclosed by the optical components (30, 31), the component carrier (20), and the boundary structure (90), but in the embodiment according to FIG. 2, the enclosed volume within the boundary structure (90) includes a small gas volume (110) which may particularly contain nitrogen or air. As a result, the viscoelastic cladding material (80) can be maintained in place, while in the case of volume change, particularly as a result of thermal expansion, a significant increase in pressure cannot occur simultaneously, especially since any pressure change can be compensated by the compressible gas. The enclosed gas volume can advantageously be positioned in this manner so as not to come into contact with the free-form structure (50). In this case, the enclosure of the cladding structure (70) can be implemented in such a way that the cladding material (80) contacts the structural element of the optical assembly (10) comprising the solid material, preferably at least 70%, particularly preferably at least 80%, particularly at least 90%, 95%, or 98% of its surface.
[0076] FIG. 3 illustrates a schematic diagram of a further likely preferred embodiment of an optical assembly (10) according to the present invention. In this case, the cladding material (80) and the material (100) of the boundary structure (90) comprise the same or similar polymer that can be cured by UV exposure. Here, the UV exposure applied to the material (80, 100) and the material (80, 100) is selected such that only one outer region of the material (80, 100), also referred to as the "shell," is cured during UV exposure, while the inner region of the cladding material (80), also referred to as the "core," remains liquid. Alternatively, the outer region of the material (80, 100) may have higher viscoelasticity compared to the inner region of the cladding material (80). In this way, a harder shell can be formed, which can retain the liquid fraction of the cladding material (80) in a suitable place within the core, and thus particularly in the area around the free-form structure (50). This embodiment can be obtained by using a highly absorbent photoinitiator within the material (80, 100) to absorb UV light for curing within a gap determined outside, particularly preferably 100 μm or less, more preferably 50 μm or less, thereby preventing curing of the polymer on the free-form structure (50) at a larger gap, and keeping the free-form structure surrounded by the liquid cladding material (80).
[0077] FIG. 4 illustrates a schematic diagram of a preferred embodiment of a method (200) for manufacturing an optical assembly (10) according to the present invention, particularly described in one of the exemplary embodiments according to FIG. 1 to 3.
[0078] In the providing step (210) according to method step a), a step of providing at least one component carrier (20) is performed.
[0079] In the attachment step (220) according to method step b), a step of attaching at least one optical component (30, 31) having at least one optical coupling point (40, 41) to a component carrier (20) is performed.
[0080] In the connection step (230) according to method step c), a step of connecting at least one optical free-form structure (50) to at least one optical coupling point (40, 41) is performed. Preferably, the optical free-form structure (50) can be manufactured by a stacked nanofabrication method, particularly preferably by 2-photon polymerization.
[0081] In the surrounding step (240) according to method step d), the optical free-form structure (50) is surrounded in at least a portion of the area by at least one cladding structure (70), and the cladding structure (70) comprises at least one viscoelastic cladding material (80). According to the present invention, the cladding material (80) is selected in this manner to have a storage modulus having a maximum value of 1000 kPa. Particularly preferably, the storage modulus may be greater than the loss modulus of the cladding material (80) by up to 1000 times. If the cladding material (80) comprises at least one liquid-curable viscoelastic material, the optical free-form structure (50) may be surrounded by the liquid-curable viscoelastic material in at least a portion of the area, and the surrounding step (240) may include a curing step comprising at least partial curing of the liquid-curable viscoelastic material.
[0082] In the creation step (250) according to method step e), the step of creating at least one boundary structure (90) occurs in such a way that the boundary structure (90) and the optical component (30) form at least a partial enclosure for the cladding structure (70). In a preferred embodiment according to FIGS. 1 to 3, the component carrier (20) likewise contributes to surrounding the cladding structure (70). As schematically illustrated in FIGS. 1 and 2, the boundary structure (90) can be created by attaching the boundary structure (90) to the cladding structure (70). According to an embodiment according to FIG. 3, the step of creating the boundary structure can be performed by processing the shell of the cladding structure (70) while the viscoelastic cladding material is retained within the core of the cladding structure (70).
[0083] For further details regarding FIGS. 2 to 4, refer to the description in FIG. 1. Explanation of the symbols
[0084] 10: Optical assembly 20: Component Carrier 30, 31: Optical components 40, 41: Optical coupling points 50: Free-form structure 60: Material (of free-form structures) 70: At least one cladding structure 80: (Viscoelastic) Cladding Material 90: Boundary structure 100: Material (of boundary structure) 110: Gas volume 200: Method for manufacturing an optical assembly 210: Provisioning step 220: Attachment step 230: Connection Step 240: Encircling stage 250: Application step
Claims
Claim 1 An optical assembly (10), comprising: - at least one component carrier (20); - at least one optical component (30, 31) attached to the component carrier (20), wherein the optical component (30, 31) has at least one optical coupling point (40, 41); - at least one optical free-form structure (50) connected to the optical coupling point (40, 41); - at least one cladding structure (70) surrounding the optical free-form structure (50) in at least a portion of the area, wherein the cladding structure (70) comprises at least one viscoelastic cladding material (80); - at least one boundary structure (90), wherein the boundary structure (90) and at least one optical component (30, 31) form at least a partial enclosure for the cladding structure (70), and the cladding The material (80) is an optical assembly (10) having a storage modulus having a maximum value of 1000 kPa. Claim 2 An optical assembly (10) according to claim 1, wherein the storage modulus is greater than the loss modulus of the cladding material (80) by up to 1000 times. Claim 3 An optical assembly (10) according to paragraph 2, wherein the storage modulus is greater than the loss modulus of the cladding material (80) by up to 100 times, and the storage modulus has a maximum value of 100 kPa. Claim 4 In any one of claims 1 to 3, the value for the storage modulus is set in such a way that, within ambient conditions set for the use of the optical assembly (10), the cladding material (80) substantially maintains its spatial position and shape, and furthermore, at least in some area, surrounds the free-form structure (50). Claim 5 An optical assembly (10) according to any one of claims 1 to 4, wherein - the storage modulus has a value of 0.1 kPa to 60 kPa, preferably 1 kPa to 30 kPa, more preferably 2 kPa to 15 kPa; and - the loss modulus has a value of 0.01 kPa to 30 kPa, preferably 0.05 kPa to 10 kPa, more preferably 0.1 kPa to 5 kPa. Claim 6 An optical assembly (10) wherein, in any one of claims 1 to 5, with respect to the shear modulus of the cladding material (80), in the local relative movement between the cladding structure (70) and the free-form structure (50) within the ambient conditions set for use of the assembly (10), the shear stress of the cladding material (80) surrounding the free-form structure (50) is very small, so that the free-form structure (50) substantially maintains its spatial position and shape. Claim 7 An optical assembly (10) wherein, in any one of claims 1 to 6, the cladding material (80) comprises at least one liquid, locally curable polymer, and the cured cladding material (80) forms at least a portion of the boundary structure (90). Claim 8 An optical assembly (10) wherein, in any one of claims 1 to 7, the region around the free-form structure (50) corresponding to at least twice the value of the diameter of the free-form structure (50), preferably taking a value of at least 4 μm, comprises at least one liquid viscoelastic material. Claim 9 In claim 8, the liquid viscoelastic material is 1 cm 2 / s to 1,000,000 cm 2 Optical assembly (10) having a viscosity of / s. Claim 10 In any one of claims 1 to 9, the boundary structure (90) is configured in such a way that, in the event of a change in the volume of the cladding structure (70), the pressure inside the cladding structure (70) is substantially maintained constant, the optical assembly (10). Claim 11 In any one of claims 1 to 10, the boundary structure (90) comprises at least partially a cladding material (80), an optical assembly (10). Claim 12 In any one of claims 1 to 11, the boundary structure (90) comprises an optical assembly (10) including an elastic material. Claim 13 An optical assembly (10) in any one of claims 1 to 12, wherein at least a partial enclosure for the cladding structure (70) comprises a closed volume (110) that is not completely filled by the cladding material (80). Claim 14 An optical assembly (10) in any one of claims 1 to 13, wherein the cladding material (80) and the material (60) included in the free-form structure (50) are optically transparent, and the cladding material (80) has a lower refractive index than the material (60) included in the free-form structure (50). Claim 15 In any one of claims 1 to 14, - an optical assembly (10) further comprising at least one opening in at least a partial enclosure for a cladding structure (70), wherein the opening is configured for pressure equilibrium. Claim 16 In particular, a method (310) for manufacturing an optical assembly (10) according to any one of claims 1 to 15, the method comprising: a) providing at least one component carrier (20); b) attaching at least one optical component (30, 31) having at least one optical coupling point (40, 41) to the component carrier (20); c) connecting at least one optical free-form structure (50) to at least one optical coupling point (40, 41); d) surrounding the optical free-form structure (50) with at least one cladding structure (70) in at least a portion of the area, wherein the cladding structure (70) comprises at least one viscoelastic cladding material (80); e) creating at least one boundary structure (90) in such a manner that the boundary structure (90) and the optical component (30) form at least a partial enclosure for the cladding structure (70). A method (310) in which a cladding material (80) is selected in such a way that it has a storage modulus having a maximum value of 1000 kPa. Claim 17 In claim 16, the cladding material (80) is selected in such a way that the storage modulus is greater than the loss modulus of the cladding material (80) by up to 1000 times, in a method (310). Claim 18 In claim 16 or 17, the optical free-form structure (50) is manufactured by a stacked nanofabrication method, particularly preferably by 2-photon polymerization, method (310). Claim 19 In any one of claims 16 to 18, at least one liquid viscoelastic material is selected for the cladding material (80), and at least one optical free-form structure (50) is surrounded by the liquid viscoelastic material (80) in at least a portion of the area, and said liquid viscoelastic material is 1 cm 2 / s to 1,000,000 cm 2 Method (310) having a viscosity of / s. Claim 20 In claim 19, the liquid curable viscoelastic material is cured at least partially, preferably positionally selectively, during the curing step, in a method (310).