LOCALIZATION OF OPTICAL COUPLING POINTS

Description

Field of invention

[0001] The present invention lies in the field of optical interconnection of optical components by means of an optical coupling point and relates to a method and an arrangement for localizing an optical coupling point as well as a method for generating a microstructure at an optical coupling point. The optical components can be, for example, micro-optical components such as lasers, optical fibers, optical chips with passive or active waveguides, photodetectors, lens systems, or optical filters. Other types of optical components are conceivable. The present methods and arrangement are particularly applicable in integrated optics and optical assembly and interconnection technology. However, further areas of application are possible. State of the art

[0002] According to the prior art described in Hasegawa M: "Alignment Method of Polymer Waveguide and Optical Component Using Fluorescence", Japan Journal of Applied Physics, Vol. 44, No. 33-36, pages L1085-L1087, methods and arrangements for locating an optical coupling point are known. Depending on the type of optical component, the position and orientation of the optical coupling point can be determined, in particular, by a combination of camera images and a confocal detection method of an imaging system, which may be part of a lithography system. It is often necessary for the optical components to be transparent to the light used to detect the coupling point and / or to exhibit a contrast with respect to refractive index, color, or reflectance that is detectable by an imaging optical device. However, this is not the case in many material systems.In the field of integrated optics, for example, optical fibers, optical fiber arrays, or material systems for integrated optical chips exhibit very low refractive index contrast, which significantly complicates the detection of waveguides at the optical coupling point. Furthermore, optical chips or individual layers of these chips may not be transparent at the wavelengths used for coupling point detection; this is particularly true when the waveguide to be detected is obscured by metallization. In addition, many optical components lack optically detectable features, such as alignment marks, that would allow the location and / or orientation of the optical coupling point to be determined.

[0003] As described in Katagiri, T. et al., Optical microscope observation method of a single-mode opticalfiber core for precise coreaxis alignment, Journal of Lightwave Technology, 2(3), 1984, pp. 277-28, a common technical requirement, particularly with optical fibers, is to identify their cores as precisely as possible. This is especially necessary when joining two optical fibers in so-called "splicing" processes. Despite the low refractive index contrast of typical optical fibers, interfaces between the fiber core and cladding can be detected under optical microscopes by a slight shadowing effect when using suitable back-collimated flood illumination. This requires that the fiber axis is approximately located in the focal plane of the microscope. However, in many cases, it is not possible to implement back-collimated flood illumination. For example, in optical modules such as...Optical transmitters, optical fibers, and waveguides are usually mounted on non-transparent substrates, making back-illumination impossible. In other cases, the optical fibers are bundled into fiber arrays, so that a faint umbra is superimposed on other optically higher-contrast structures within the fiber array, thus significantly hindering detection.

[0004] US 2006 / 0067625 A1 discloses a device and method that establishes an optical connection between a waveguide and an optical connection component that introduces light into the waveguide or receives light emitted from the waveguide. The device comprises an excitation light source that emits light into the waveguide via the optical connection component, causing the waveguide to fluoresce; a viewing unit that observes the waveguide from a side face, this side face being different from the end face through which light is coupled into or emitted from the waveguide, and that receives fluorescence light emitted from the waveguide; and a connection-setting component that adjusts the optical connection between the optical connection component and the waveguide based on the intensity of the received fluorescence light.

[0005] WO 2017 / 059960 A1 discloses a further method for detecting the fiber core of an optical fiber when viewed from above a facet, with the viewing direction perpendicular to the facet and parallel to the axis of the fiber core. To improve the visibility of the fiber core at one end, additional light can be coupled into the fiber core from the other end of the fiber. However, it is necessary to collect the light coupled out of the fiber core using the imaging system. This proves particularly difficult when the optics of a lithography system are to be used for imaging. Often, the axes of the optical fiber or the optical waveguide to be located lie in the focal plane of the lithography system, so that the light coupled out along the axis cannot be detected even with the aid of high numerical aperture lenses.

[0006] WO 2018 / 024 872 A1 discloses a method and a device for the lithographic production of a target structure on a non-planar starting structure by exposing a photoresist using at least one lithography beam.The method comprises the following steps: a) capturing a topography of a surface of a non-planar source structure; b) using at least one test parameter for the lithography beam and determining an interaction of the lithography beam with the source structure and the resulting change in the lithography beam and / or the target structure to be produced; c) determining at least one correction parameter for the lithography beam such that the change in the lithography beam and / or the target structure to be produced caused by the interaction of the lithography beam with the source structure is reduced; and d) producing the desired target structure on the source structure by exposing the photoresist using the at least one lithography beam and the at least one correction parameter for the lithography beam.

[0007] As described, for example, in Barry R. Masters, Review of Handbook of Biological Confocal Microscopy, Third Edition, Journal of Biomedical Optics 13(2), 029902, 2008, imaging techniques from the field of fluorescence microscopy can also be used to localize an optical coupling point. For this purpose, fluorescence radiation can be spatially resolved and / or spatially resolved in a sample under investigation, and the resulting contrast can be used for imaging.

[0008] According to Denk, Winfried, James H. Strickler, and Watt W. Webb, Two-photon laser scanning fluorescence microscopy, Science Vol. 248, No. 4951, 1990, pp. 73-76, spatially resolved excitation can also be achieved using multiphoton absorption processes. Object of the invention

[0009] Based on this, the object of the present invention is to provide a method and an arrangement for localizing an optical coupling point, as well as a method for generating a microstructure at the optical coupling point, which at least partially overcome the aforementioned disadvantages and limitations of the prior art. The method and the associated arrangement are intended to be particularly suitable for use in lithography systems with which structures such as optical waveguides, lenses, mirrors, or other functional elements that are optically connected to or aligned with the coupling point to be detected can be generated with very precise alignment at the optical coupling point.To achieve the lowest possible coupling losses in the optical connection between the optical coupling point to be located and the lithographically produced structures, the most precise possible localization of the optical coupling point with respect to position and orientation in the coordinate system of the lithography unit is desirable. For this purpose, a relative positioning tolerance of preferably better than 1 µm, particularly preferably better than 200 nm, and especially better than 50 nm, is highly desirable. Disclosure of the invention

[0010] This problem is solved by a method and an arrangement for localizing an optical coupling point, as well as by a method for generating a microstructure at the optical coupling point, with the features of the independent claims. Advantageous embodiments, which can be implemented individually or in any combination, are described in the dependent claims.

[0011] Furthermore, the terms "preferably", "in particular", "for example", or similar terms are used in the following in conjunction with optional features without limiting alternative embodiments. Features introduced by these terms are therefore optional, and it is not intended that these features limit the scope of protection of the claims, and in particular the independent claims.

[0012] In a first aspect, the present invention relates to a method for locating an optical coupling point, comprising the following steps, which are preferably carried out in the specified order, beginning with step a) and ending with step d), wherein one or more, in particular immediately successive, steps can also be carried out at least partially simultaneously: a) Providing an optical component comprising an optical coupling point, wherein the optical coupling point has an interaction area that lies outside a volume enclosed by the optical component; b) Generating optical radiation in a generation area, wherein the generation area overlaps at least partially with the interaction area of ​​the optical coupling point, and wherein a medium located in the generation area is illuminated by light, which is modified by the medium in such a way that the optical radiation is generated; c) Detecting at least a portion of the generated optical radiation in a detection area, wherein the detection area overlaps at least partially with the interaction area of ​​the optical coupling point, and determining a spatially resolved distribution of the detected portion of the generated optical radiation;and d) Determining the localization of the optical coupling point from the determined spatially resolved distribution of the detected part of the generated optical radiation, ; wherein the detection of at least part of the generated optical radiation takes place through the optical coupling point.

[0013] According to step a), an optical component is provided. The term "optical component" refers to at least one optical element designed to emit, receive, modify, or transmit light. The optical component may, for example, comprise an optical fiber or be deposited on a planar or non-planar substrate and preferably be fabricated by a two- or three-dimensional microstructuring process. In the case of a substantially planar structure, the optical component may also be referred to as an "optical chip." An optical component may comprise a single or multiple optical elements.Preferably, the optical component is selected from the group comprising light-guiding single-mode or multi-mode fibers made of organic or inorganic materials; semiconductor-based integrated optical chips, in particular lasers, optical amplifiers, photodiodes, superluminescent diodes or silicon photonic chips; integrated optical chips based on semiconductors or dielectric materials, preferably glasses, silicon dioxide, silicon nitride or polymers; optical circuit boards; or optical elements for free-beam optics, in particular lenses, beam splitters, insulators, thin-film filters, mirrors, or diffraction gratings. The optical components can comprise optical waveguides with low index contrast, e.g., glass-based optical waveguides, or waveguides with medium or high index contrast, e.g., semiconductor-based waveguides. Other types of optical components are conceivable, in particular filters, power dividers, or electro-optical modulators.The optical component can, in principle, comprise any combination of the aforementioned optical elements.

[0014] The optical component provided according to step a) includes an optical coupling point. The term "optical coupling point" refers to a part of the optical component to be connected, through which light can be coupled into or emitted from the component. In simple optical components, such as optical fibers or edge-emitting integrated optical chips, the optical coupling point is often also referred to as a "facet" or "waveguide facet." In photodiodes, the optical coupling point is often identical to a so-called "active area" of the pn junction used for detection, within which the incident light leads to the generation of an electrical signal. In lasers, it can be the light-emitting area on the edge or on the surface of the corresponding chip.More complex designs of optical coupling points can be implemented, for example, as so-called grating couplers (see Taillaert, Dirk, Peter Bienstman, and Roel Baets, Compact efficient broadband grating coupler for silicon-on-insulator waveguides, Optics Lett. 29 (23), 2004, pp. 2749-51) in silicon photonics or as so-called "inverse tapers" or etched micromirrors (see Behfar, Alex et al., Horizontal cavity surface-emitting laser (HCSEL) devices, Vertical-Cavity Surface-Emitting Lasers IX. Vol. 5737, International Society for Optics and Photonics, 2005). The optical coupling points can include or be equipped with beam-shaping elements already produced by multiphoton polymerization.

[0015] The optical coupling point has an interaction area. The term "interaction area" of the optical coupling point refers to a spatial region that optically interacts with the coupling point. A selected point within this spatial region then interacts with the optical coupling point. (1) if light emitted from the optical coupling point can at least partially reach the selected point of the spatial region, or (2) if optical radiation emitted by an isotropically radiating point light source placed at the selected point of the spatial region can at least partially be coupled into the optical coupling point.

[0016] In case (1), the selected point in the spatial region lies within a so-called "emission range" of the optical coupling point; in case (2), it lies within a so-called "acceptance range" of the optical coupling point. The emission range of the coupling point can be described, based on a common definition for so-called "Gaussian beams," as follows: A point belongs to the emission range of the optical coupling point if the intensity of the light emitted by the optical coupling point measured at that point is more than 1 / e 2 times the maximum intensity value measured at the same distance from the optical coupling point, for example, on the axis of the Gaussian beam.Similarly, the acceptance range can be defined as follows: A point belongs to the acceptance range of the optical coupling point if the coupling efficiency of the light emitted by a point light source at that point is more than 1 / e 2< times the maximum coupling efficiency achieved by a point light source optimally positioned at the same distance from the optical coupling point, for example, on the axis of the Gaussian beam. Depending on the specific application, a different factor, such as 0.01 (-20 dB) or 0.001 (-30 dB), can be used instead of the aforementioned factor of 1 / e 2<. The interaction range assigned to each selected optical coupling point can therefore alternatively be referred to as the "acceptance range" or the "emission range".In a particularly preferred embodiment of the present invention, the interaction region lies outside a volume encompassed by the optical component. In an alternative embodiment, however, the interaction region can also encompass wholly or partially the volume of the optical component or of a waveguide core encompassed by the optical component. In the case of an exemplary optical component comprising a simple waveguide at the end of which the optical coupling point is arranged, the interaction region can have a conical volume, also referred to as an "acceptance cone" or "emission cone".

[0017] According to step b), optical radiation is generated in a spatial region referred to as the "generation region." The terms "generation" and "production" in relation to optical radiation denote the provision of optical radiation, in particular by irradiating the generation region with light, whereby the light in the generation region can be modified in such a way as to generate the optical radiation. Various effects can be used to generate the radiation, such as those based on light scattering, phosphorescence, fluorescence, luminescence, or related processes. In processes based on light absorption and subsequent emission, the simultaneous or sequential absorption of multiple photons can also be used.The optical radiation used for excitation can be provided by the optical coupling point itself or by a separate optical system that may be set up to generate a laser beam.

[0018] The term "light" refers to photons provided by a light source that generate the desired optical radiation in the generating area. The light emitted into the generating area to produce the optical radiation can be provided as constant-power optical waves or in the form of short light pulses; that is, the light source can be designed as a continuous-wave light source or as a pulsed light source. In the case of a pulsed light source, light pulses with a pulse duration of preferably at most 10 ps, ​​more preferably at most 1 ps, more preferably at most 200 fs, and more preferably at most 100 fs, can be used at a repetition rate of preferably at least 1 MHz, more preferably at least 10 MHz, more preferably at least 25 MHz, and more preferably at least 100 MHz.For this purpose, laser light sources selected from fiber-based femtosecond lasers or pulsed solid-state lasers such as titanium-sapphire lasers or diode lasers are particularly suitable, which can be combined with frequency conversion units, for example for frequency doubling, sum frequency generation, or difference frequency generation. In this preferred configuration, the light source can be used in particular to excite the luminescence of multiphoton absorption processes. For example, multi-stage absorption processes can also be used to excite the luminescence radiation, whereby part of the excitation or de-excitation light can be directed into the generation area via the optical component and another part via the lens.

[0019] The optical radiation generated according to step b) can, in principle, comprise any type of optical radiation having a wavelength in the range of the optical spectrum or an adjacent spectral range. While the visible optical spectrum has wavelengths from 380 nm to 780 nm, the infrared spectral range comprises wavelengths from 780 nm to 1 mm, in particular from 780 nm to 3 µm (near-infrared, "NIR") or from 3 µm to 8 µm (mid-infrared, "MIR"), and the ultraviolet spectral range comprises wavelengths from 1 nm to 400 nm, preferably from 100 nm to 400 nm, in particular from 400 nm to 315 nm ("UV-A"), from 315 nm to 280 nm ("UV-B") or from 280 nm to 100 nm ("UV-C").

[0020] According to step b), the generation area overlaps at least partially with the interaction area of ​​the optical coupling point. The two areas may have an overlap that is smaller than either of them; alternatively, the two areas may be completely identical, or one area may be completely encompassed by the other.

[0021] According to step c), at least a portion of the generated optical radiation is detected within a detection area, and a spatially resolved distribution of the detected portion of the generated optical radiation is determined, whereby the detection area overlaps at least partially with the interaction area of ​​the coupling point. Here, too, the two areas can have an overlap that is smaller than either of the two areas; alternatively, the two areas can be completely identical, or one area can be completely encompassed by the other.

[0022] The terms "detection" and "acquisition" with respect to the generated optical radiation refer to a metrological recording of the optical radiation or a portion thereof, particularly with regard to its power. The detected radiation may be subjected to further modifications, especially filtering with respect to a wavelength or polarization, before the power is determined. In a case where the optical coupling point is used to detect the generated optical radiation, it is possible to measure how well the optical radiation from a given source location within the generation area can couple into the optical coupling point.In another case, where a separate optical system is used to detect the generated optical radiation, the optical system can, in particular, measure the power of the optical radiation or a portion thereof at a specific point of generation within the generation area. In both cases, it is sufficient that a portion of the optical radiation generated in an area overlapping the generation area with the detection area is detected, while another portion of the optical radiation may be emitted in spatial directions that cannot be detected by a measuring unit designed for optical radiation detection.

[0023] With regard to spatially resolved distribution, the terms "determine" and "ascertain" refer to the determination of the spatially resolved distribution of the portion of the generated optical radiation detected within the detection range, in particular by identifying and evaluating recorded measurements and / or by applying a model for the optical coupling point or the interaction area of ​​the optical coupling point. The term "spatially resolved distribution" with respect to optical radiation denotes a quantity that is specified as a function of a spatial position, preferably in the form of a position vector in a three-dimensional coordinate system, within a spatial region. In particular, the quantity used here can be, depending on the location, the power of the detected optical radiation or the coupling efficiency of the optical power generated by the optical system at the respective spatial position.

[0024] According to step d), the desired localization of the optical coupling point is determined from the spatially resolved distribution of the portion of the generated optical radiation detected within the detection range, as determined during step c). The term "localization" includes both a specification of a spatial position and an orientation of the optical coupling point or the interaction area of ​​the optical coupling point. The information regarding the spatial position can, in particular, include a position vector in a coordinate system, preferably a three-dimensional coordinate system.The orientation information can, in particular, comprise one or more three-dimensional orientation vectors, especially preferably in the same coordinate system used to specify the position vector, wherein one of the orientation vectors preferably indicates a direction in which light can be emitted from the optical coupling point or from which efficient coupling of light into the optical coupling point is possible. As explained in more detail below, in a particularly preferred embodiment, the position vector and the orientation vector can be specified in a three-dimensional coordinate system defined by a lithography system used in a lithography process.For diverging beams, an optical axis of a beam emitted or received by the optical coupling point can be used to describe its orientation or interaction area. Additionally, at least one further orientation vector can be specified, in particular an orientation vector that defines a rotational orientation of the coupling point with respect to an optical axis, and thus, in particular, specifies a spatial direction of a polarization of the light emitted or received by the coupling point.

[0025] With regard to the localization of the optical coupling point, the terms "determine" or "ascertain" refer to the determination of a quantity from other quantities that have been measured or determined based on a model. From the spatially resolved distribution of the portion of the generated optical radiation detected within the detection range, determined during step c), both the position and orientation of the optical coupling point can be determined. In addition to the position and orientation of the optical coupling point, further information about the lateral shape of the interaction area and / or other spatially dependent properties of the interaction, such as polarization dependence, can also be obtained.In most cases, the position and orientation of the optical coupling point or its interaction region can be directly deduced from the spatially dependent distribution of the power measured in the detection area, as determined according to step c). The coupling point's position can often represent a location of smallest lateral extent within the interaction region, for example, the tip of a conical region. Alternatively or additionally, the position and orientation of the optical coupling point can be determined by an observation or model-based expectation that no significant excitation of optical radiation occurs within the optical component, particularly within a waveguide it encompasses.This typically results in the appearance or disappearance of the detected optical radiation at the coupling point, particularly in the form of an abrupt contrast, which can be used to determine the position of the optical coupling point. If the optical radiation is locally excited by a separate optical system comprising a lens, it can be particularly advantageous to detect, in addition to the radiation coupled into the optical component through the optical coupling point, also portions of the radiation generated in a medium but not coupled into the optical component through the optical coupling point and detected there. Detection can be performed using the lens used for excitation or by means of an additional lens.Furthermore, the interaction region expected for the optical coupling point is generally calculable or modelable, particularly by applying Kirchhoff's diffraction integrals. By comparing the model-based interaction region or the model-based distribution of the detected optical power with the optical power measured within the detection region, the position of the optical coupling point and its interaction region can be deduced. This makes it possible to determine the position and orientation of the optical coupling point without actually measuring the spatial region encompassing the optical coupling point. The position and orientation of the optical coupling point can then be determined, for example, by extrapolating the distribution of the detected radiation determined within the interaction region.For example, in the case of a conical interaction region, it is sufficient to capture only the expanded area of ​​the cone, while the position of the cone's apex is determined by extrapolation. In a particular embodiment, the localization of the optical coupling point can be determined at a wavelength of the generated radiation and / or the light used for its generation that differs from the operating wavelength of the optical component. In this embodiment, chromatic effects, such as wavelength-dependent refraction of the optical radiation at an interface, can occur, which can be compensated for by a model. In a further embodiment, the position and orientation of the optical coupling point are sufficiently wavelength-insensitive, so that no compensation for chromatic effects is necessary.According to the invention, it is irrelevant how the optical radiation is generated in the generation area, as long as the spatially resolved distribution of the optical radiation is detected through the optical coupling point. In this case, the spatially resolved distribution of the optical radiation detected through the coupling point can be determined, for example, by sequentially generating the optical radiation at different points within or outside the interaction area with a known spatial distribution, and the optical power measured through the coupling point reflects the spatial dependence of the coupling efficiency and thus the shape of the interaction area.The term "through the optical coupling point" here refers to an embodiment according to the invention with respect to guiding the optical radiation or the light generating the optical radiation in such a way that the optical radiation or the light generating the optical radiation actually passes through the optical coupling point. Only in this way can it be ensured that the spatially resolved distribution of the detected optical radiation actually indicates the localization of the optical coupling point or the associated interaction area.

[0026] For the generation of optical radiation in the generation area, the generation area comprises at least a portion of a medium that modifies the incident light in such a way as to produce optical radiation. The generation area can be wholly or partially filled with this medium, where the term "medium" refers to a substance designed to generate optical radiation from the light incident on the generation area. By providing this medium in the generation area, the problem can be solved, in particular, that light emitted by the optical component often cannot be efficiently coupled into the lens, or conversely, that light projected into space by a lens often cannot be efficiently directed into the optical component.Advantageously, the medium can completely or at least partially fill an overlapping area between the generating and detection regions. In a particularly preferred embodiment, a sub-region of the generating or detection region can be addressed sequentially. A raster or scanning method can be used for this purpose, which, for example, can change the relative position of the lens to the optical component. Alternatively, stationary lenses can be used, and rasterization can be achieved with the aid of scanning mirrors, which allow specific sub-regions of the generating or detection region to be addressed. Alternatively or additionally, detector arrays or image sensors, such as CCD or CMOS arrays, can also be used in combination with stationary lenses for spatially resolved detection of radiation.

[0027] In a preferred embodiment, the medium located in the generation area can comprise scattering centers that scatter incident light in such a way that scattered radiation is generated which, as the desired optical radiation, can completely or at least partially fill the detection area. In an alternative, also preferred embodiment, the medium located in the generation area can contain a luminescent dye, wherein the luminescent dye, when exposed to light, generates luminescent radiation which, as the desired optical radiation, can likewise completely or at least partially fill the generation area. Single-photon or multi-photon absorption processes can be used to excite the luminescence.The term "luminescence" describes the emission of light by a substance that is designed to be excited to a higher state by absorbing energy, with a return to the ground state occurring through the emission of radiation. If the emission of radiation occurs immediately after the absorption of light, the term "fluorescence" is usually used; if the return to the ground state takes longer, the term "phosphorescence" is used. However, other types of luminescence are conceivable.Alternatively, the generation area can also contain a starting material designed to produce the luminescent dye. When exposed to the incident light, the starting material first generates the luminescent dye, which, upon further exposure to the light, then produces the desired luminescent radiation, resulting in the optical radiation within the generation area. Other types of media are conceivable.

[0028] In a particular embodiment, the optical component can wholly or partially encompass the medium that modifies the incident light in such a way as to generate optical radiation. Preferably, the medium within the optical component can be in the form of a waveguide core into which scattering or luminescent substances are introduced. Alternatively or additionally, intrinsic fluorescence of the waveguide material can be used.

[0029] In a further embodiment, the medium can comprise a photoresist, wherein the dose introduced into the photoresist for generating the optical radiation is preferably below a dose threshold for polymerization of the photoresist. The term "photoresist" can alternatively be used instead of "photoresist." The photoresist can comprise scattering centers or a luminescent dye. Preferably, an excitation wavelength, power, pulse shape, or irradiation duration for generating the optical radiation using the luminescent dye can be selected such that no unintentional exposure of the photoresist occurs. After localization of the optical coupling point according to the method described herein, a microstructure can be fabricated at the localized optical coupling point according to the method described in more detail below.

[0030] In a preferred embodiment of the present invention, the light from the optical component can be emitted through the optical coupling point in such a way that the light propagates into the interaction or emission region of the optical coupling point and generates the desired optical radiation there, which is spatially resolved and evaluated by a lens. Since direct detection of the light emitted by the optical component is generally not possible even with lenses of high numerical aperture (NA), the desired optical radiation can be detected in the entire interaction region or at least a part thereof, particularly by introducing scattering centers or luminescent dyes into the interaction region.Spatially resolved detection of the optical radiation captured by the objective lens enables direct measurement of at least a portion of the interaction area of ​​the optical coupling point. This spatially resolved detection of the optical radiation can be performed using known microscopy techniques, preferably with a camera or a confocal microscope.

[0031] In a further preferred embodiment of the present invention, light can be emitted from a separate optical system comprising a lens in such a way that the light propagates into the interaction region or acceptance region of the optical coupling point and generates the desired optical radiation there, which is then detected and evaluated by the optical component through the optical coupling point. Since even with lenses of high numerical aperture (NA) direct coupling of the light emitted by the lens into the optical component is generally not possible, the desired optical radiation can be generated in the entire interaction region or at least a part thereof and coupled into the optical coupling point, particularly by introducing scattering centers or luminescent dyes into the interaction region of the optical coupling point as described above.The detection of the optical radiation coupled into the optical component, which preferably includes a waveguide, can preferably be performed directly at an output of the optical component. For this purpose, a measuring unit, particularly preferably a power detector, especially in the form of an optical power measuring head, can preferably be attached to the output of the optical component. This detector can also be equipped with filters, for example, for detecting specific wavelengths or polarization states. This configuration can be particularly advantageous for optical fibers, such as single-core or multi-core fibers. However, the power detector can also be provided as part of the optical component, for example, in the case of integrated photodiodes, which can be configured to detect at least a portion of the power of one or more waveguides.Additionally, the coupled optical radiation can also be detected by the lens used for excitation itself, whereby, as described below, coupling points on the optical component itself can be used. Alternatively, additional lenses can be used to detect the optical radiation. Generally, a lock-in principle can be used for the metrological detection of the optical radiation in order to distinguish background radiation, such as external illumination, from the optical radiation generated for detection at the coupling point.

[0032] In a particular embodiment, coupling structures on the optical component, especially on a waveguide encompassed by the optical component and located within the addressable field of view of the lens, can be used to re-emit a portion of the optical power coupled into the optical component back towards the lens in such a way that it can be detected by the lens. Scattered radiation emitted by the waveguide, particularly as a result of imperfections such as surface roughness, or by scattering structures created for this purpose, can also be used for this purpose.In this particular configuration, the optical radiation generated in the interaction zone of the coupling point can have a wavelength that differs from the operating wavelength of the waveguide. This means that capturing the scattered radiation generated by the waveguide via radiating elements does not necessarily result in losses at the operating wavelength itself. For example, waveguide sections made of so-called "sub-wavelength gratings" (SWGs) can be used. These gratings cause the optical radiation generated in the acceptance volume to be emitted, while they do not affect, or only minimally affect, optical signals at the operating wavelength of the optical component. Furthermore, sections of the waveguide can be equipped with additional dyes that can be excited by the coupled optical radiation, and the emitted light coupled out of the waveguide can also be captured by the objective lens.

[0033] In a further embodiment, the optical component can have a group of optical coupling points, whereby it can be advantageous to integrally detect the optical radiation coupled into the entire group, particularly if the interaction regions assigned to the individual optical coupling points have sufficiently large, non-overlapping spatial regions. An example of this is a multi-core fiber at the end of which a common photodetector is attached, the active area of ​​which extends over all the cores of the multi-core fiber.

[0034] In another aspect, the present invention relates to an arrangement for localizing an optical coupling point, wherein the arrangement comprises: an optical component comprising at least one optical coupling point, wherein the optical coupling point has an interaction area that lies outside a volume encompassed by the optical component; an optical device configured to generate optical radiation in a generation area and / or to detect at least a portion of the generated optical radiation in a detection area, wherein the generation area and the detection area overlap at least partially with the interaction area of ​​the optical coupling point; and an evaluation unit configured to determine a spatially resolved distribution of a detected portion of the optical radiation and to determine the localization of the optical coupling point from the determined spatially resolved distribution of the detected portion of the optical radiation. wherein the arrangement is set up such that the detection of at least part of the generated optical radiation takes place through the optical coupling point.

[0035] The term "optical device" refers to a device designed for generating and detecting optical radiation and comprising optical components designed for this purpose, in particular a light source designed for illuminating the medium located in the generation area with light, which can shine light into the generation area via the optical coupling point or via an optical system, a measuring unit designed for detecting at least part of the generated optical radiation in a detection area, in particular in the form of a power detector, which may be included by the optical component or the optical system or which may include components of the optical component and components of the optical system, and may include an optical system designed for transmitting and optionally modifying generated and / or detected optical radiation.

[0036] Preferably, the light source can be configured as a pulsed light source, which is used to generate light pulses with a pulse duration of at most 10 ps, ​​preferably at most 1 ps, particularly preferably at most 200 fs, and especially at most 100 fs, at a repetition rate of at least 1 MHz, preferably at least 10 MHz, particularly preferably at least 25 MHz, and especially at least 100 MHz. Laser light sources such as fiber-based femtosecond lasers or pulsed solid-state lasers such as titanium-sapphire lasers are particularly suitable for this purpose. Alternatively, a continuous-wave light source can also be used.

[0037] As already mentioned, the light source is preferably configured to irradiate light into at least one spatial region, which comprises a medium for generating optical radiation by modifying the incident light. The spatial region in which optical radiation is generated by a modification of the incident light caused by the medium is hereinafter also referred to as the generation region. The generation region overlaps at least partially with the interaction region of the optical coupling point. The two regions may have an overlap area that is smaller than either of them; alternatively, the two regions may be completely identical, or one region may be completely encompassed by the other. For further details regarding the medium and its advantageous embodiments, reference is made to the remaining description.Preferably, the refractive index of the medium can be adapted to the refractive index of a lens designed to shine light onto it or to capture the generated optical radiation, in particular to improve the resolution of the lens.

[0038] As already mentioned, the term "optical system" refers to a device encompassed by the optical unit, which is configured for the transfer and optionally the modification of generated and / or detected optical radiation and, for this purpose, comprises at least one optical element, preferably at least one optical lens, wherein either the generation or the detection of optical radiation is spatially resolved. For a given vacuum operating wavelength λ of the optical component, the spatial resolution of a generation process or a detection process is preferably from 0.01 λ to 100 λ, particularly preferably from 0.05 λ to 10 λ, and especially from 0.1 λ to 10 λ. In a particularly preferred embodiment, the optical system configured for generating or detecting the optical radiation in the spatial region comprises at least one lens.To achieve high spatial resolution, lithography lenses with a high numerical aperture (NA) are particularly suitable. Here, the term "high numerical aperture" preferably refers to a numerical aperture of the lens above 0.3, particularly preferably above 0.6, and especially above 0.8 or even above 1.0. Particularly when applying the method described in more detail below for generating a microstructure at the optical coupling point, preferably by means of three-dimensional direct laser lithography, the same lens used for generating the microstructure can be used for capturing or generating the optical radiation. Besides reducing the number of components, this has the advantage that any aberrations of the lens, such as image field distortion, are negligible or at least partially compensated.In a particular embodiment, the lens can be in direct contact with a photoresist serving as an immersion medium. This photoresist can also simultaneously serve as a medium for modifying the incident light and thereby generating optical radiation. In a preferred embodiment, substances can be added to the photoresist that, with the aid of the incident light, allow the generation of optical radiation through light scattering, phosphorescence, fluorescence, luminescence, or related processes.

[0039] To determine the spatially resolved distribution of a portion of the detected optical radiation, a spatial element in which optical radiation is generated by modifying the incident light or in which generated radiation is detected can preferably be moved through the generation or detection area, and the dependence of the power of the detected radiation on the position of the spatial element can be determined. For this purpose, a beam scanner can preferably be used that allows rapid deflection of the incident beam or the detected beam, particularly perpendicular to the beam direction, across the generation or detection area. The beam scanner can preferably be selected from a so-called "galvo scanner" and a mirror scanner based on microelectromechanical systems (MEMS).The movement of the incident or detected beam along the beam direction can be achieved by moving the objective lens and / or the optical component. Alternatively, other arrangements can be used, in particular 3D scanners based on spatial light modulators or deformable mirrors. Further developments, especially based on methods from confocal microscopy or laser scanning microscopy (LSM), are also possible. laser scanning microscopy, LSM) are conceivable. The beam scanner can also be used for the lithographic production of microstructures.

[0040] In a particularly preferred embodiment, the measuring unit for determining the spatially resolved distribution of the optical radiation detected within the detection range can include a power detector, wherein the power detector is configured to determine the optical power of the optical radiation. As already explained above, the power detector can, in particular, be in the form of an optical power measuring head. Optical filters and / or beam splitters can preferably be used to select the detected optical radiation. In particular, the optical filter can include a spectral filter, which can be configured to separate the scattered radiation and the luminescent radiation. The filters used can also serve to detect selected wavelengths or polarization states.For determining the power of optical radiation, low-noise power detectors with high sensitivity for detecting small optical powers are particularly advantageous, especially PIN diodes with low-noise electronic amplifiers or photomultipliers. Alternatively or additionally, the power detector can form part of the optical component, for example, in integrated photodiodes. The measuring unit can be designed as an integral part of the optical component or the optical system, or it can comprise components of the optical component or components of the optical system. In particular, a photodiode designed as part of the optical system can be used to detect the optical radiation, while the acquisition, amplification, and evaluation of the resulting electrical signal can be performed by appropriately configured functional units of the optical system.In another preferred embodiment, the coupled optical radiation can be detected by the lens used for excitation itself, whereby, as described above, coupling points can be employed on the optical component itself. Alternatively, additional lenses can be used to detect the optical radiation. In all embodiments, a lock-in measurement principle can be used to detect the radiation and to distinguish background radiation, e.g., external illumination, from the optical radiation generated in the generation area.

[0041] The evaluation unit, which is configured to determine the localization of the optical coupling point from the acquired spatially resolved distribution of the optical radiation, may preferably be an electronically controllable device, which may in particular include a computer, a microcomputer, or a programmable chip, e.g., an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA), wherein the device can access a computer program configured to carry out at least one of the present methods. For precise localization of the interaction area of ​​the optical coupling point, the evaluation unit may be configured to perform a deconstruction of the spatial distribution of the excitation or the acquisition of the optical radiation as defined by the lens.This can be particularly advantageous if the spatial distribution of the excitation or detection in at least one spatial direction has the same or larger dimensions than the cross-section of the generating area or the detection area at the location in question.

[0042] For further details regarding the arrangement for locating the optical coupling point, in particular with regard to the optical component and the associated at least one optical coupling point, reference is made to the rest of the description in this document.

[0043] In a further aspect, the present invention relates to a method for generating a microstructure at an optical coupling point. This method comprises the following steps, which are preferably carried out in the specified order, beginning with step i), followed by step ii), although additional steps are also conceivable: i) Localization of the optical coupling point according to the optical coupling point localization method described herein; and ii) Production of a microstructure at the optical coupling point by means of a manufacturing process selected from an additive manufacturing process or a subtractive manufacturing process.

[0044] After localizing the optical coupling point, the information obtained about its position and orientation can be used to create a microstructure at the optical coupling point, in particular by deriving the position and orientation of the microstructure from the information about the localization of the optical coupling point. In a preferred embodiment, the microstructure can be an optical element directly adjacent to the optical coupling point, preferably an optical waveguide or another micro-optical element. Alternatively, the microstructure or a component thereof can be spaced apart from the optical coupling point. A preferred embodiment may include the fabrication of a microlens, a micromirror, or any combination of microlenses, micromirrors, and other micro-optical components, in particular optical waveguides.The microstructure, or a component thereof, can be aligned very precisely at the coupling point and, in particular, designed in terms of shape, position, and orientation such that efficient coupling of light with a specific amplitude and phase distribution is achieved through the microstructure into the optical coupling point. Conversely, light coupled out of the coupling point can be converted by the microstructure, or a component thereof, into a predetermined amplitude and phase distribution. Such configurations can be used, in particular, for the optical connection of two optical components, whereby the amplitude and / or phase distribution emitted by a first optical component can be modified to achieve efficient coupling into another optical component.

[0045] The term "additive manufacturing process" refers to a manufacturing process in which material is added to or applied to a starting structure, while the term "subtractive manufacturing process" refers to an alternative manufacturing process in which material is removed from the starting structure. In a preferred embodiment, material deposition or removal can be achieved using lithographic processes with suitable photoresists, in particular negative or positive resists. The optical system described above for generating or detecting optical radiation in the interaction area or parts thereof can thus also be used for the lithographic production of the microstructure at the optical coupling point. As mentioned there, the optical system can preferably include a lens with a high numerical aperture that exhibits high optical resolution.In a particularly preferred embodiment, the lens is also configured to produce three-dimensional microstructures using a three-dimensional direct-writing lithography process. Here, the term "three-dimensional direct-writing lithography process" refers to a microstructuring method that makes it possible to structure or deposit one or more materials in the form of a three-dimensional pattern or layout in an additive or subtractive manner. This allows the production of three-dimensional structures with an accuracy of preferably better than 1000 nm, particularly preferably better than 500 nm, and most preferably better than 300 nm, where the term "three-dimensional" denotes a possible shaping of the structures in one, two, or three spatial directions.The resolution of the three-dimensional direct-writing lithography process can preferably be better than 10 µm, particularly preferably better than 5 µm, and most preferably better than 2 µm, or better than 1 µm or 500 nm, where the term "resolution" refers to the largest dimension of the smallest structural element that can be produced by the process. The three-dimensional direct-writing lithography process can preferably be designed such that it can be carried out under normal atmospheric conditions and does not require a vacuum. In particular, additive or subtractive three-dimensional direct-writing lithography processes are suitable, which allow materials to be deposited or removed at a rate of preferably more than 50 µm 3< / s, more preferably more than 500 µm 3< / s, particularly preferably more than 1000 µm 3< / s, and most preferably more than 10 000 µm 3< / s.In a particularly preferred embodiment, the three-dimensional direct-writing lithography process can be based on the principle of multiphoton lithography. In a particular embodiment, the medium in which the optical radiation to be detected is generated can be provided in the form of an immersion medium that is in direct contact with the coupling point to be located, whereby the objective lens may or may not be in contact with the immersion medium itself. The immersion medium itself can be used as a photoresist for producing the desired microstructures or can be separated from the photoresist by a translucent membrane. In a preferred embodiment, substances can be introduced into the medium that, by means of the incident light, allow the generation of the optical radiation, in particular by light scattering, phosphorescence, fluorescence, or luminescence.In the case of a photoresist, it is particularly possible to utilize the fluorescence properties of an added component of the photoresist, especially a photoinitiator, or to additionally add fluorescent dyes. The excitation of luminescence or fluorescence can be based on single-photon or multi-photon processes.

[0046] For further details regarding the method for generating a microstructure at an optical coupling point, reference is made to the description of the methods and arrangement according to the invention for localizing an optical coupling point. Advantages of the invention

[0047] The present invention offers several advantages over prior art methods and optical systems. The present methods and arrangement for localizing the optical coupling point and for optionally generating a microstructure enable, in particular, precise localization of the at least one optical coupling point, achieving a relative positioning tolerance better than 1 µm, preferably better than 200 nm, and especially better than 50 nm. The term "positioning tolerance" refers to the sum of all statistical and systematic deviations from a metrologically determined position of the optical coupling point compared to its actual position.

[0048] The present method can, in particular by means of an interaction process by which the propagation direction of the light emitted into the production area from the optical coupling point to be localized or the lithography objective can be modified, enable at least a portion of the light emitted into the production area to be detected by the objective or by the coupling point to be localized. Effective modification of the propagation direction can preferably be achieved by means of scattering centers or by luminescent dyes. A particularly preferred embodiment includes the use of multiphoton fluorescence, preferably of a photoinitiator, by the lithography system. Since luminescence is excited only at the focus of the lithography system, spatially resolved detection of the interaction area with high resolution in three spatial directions is possible. Brief description of the characters

[0049] Further details and features of the present invention will become apparent from the following description of preferred embodiments, particularly in conjunction with the dependent claims. The respective features may be implemented individually or in combination with one another. The invention is not limited to these embodiments.

[0050] The exemplary embodiments are shown schematically in the following figures. Here, identical reference numerals in the figures denote identical or functionally equivalent elements, or elements corresponding to each other with respect to their functions.

[0051] Specifically, we show: Figure 1 Figure 1AFigure 1B: Schematic representation of a non-inventive example of a method for localizing an optical coupling point; Figure 2: Schematic representation of an inventive example of a method for localizing an optical coupling point; Figure 3: Schematic representation of a further embodiment, wherein the localization of an optical coupling point is achieved by excitation or detection of luminescence radiation; Figure 4: Schematic representation of a further embodiment, wherein the localization of an optical coupling point is achieved by excitation or detection of scattered radiation; Figure 5: Schematic representation of a further embodiment, wherein the optical coupling point is arranged offset by a distance from a surface of the optical component.Figure 6 shows a schematic representation of a further embodiment, wherein the localization of an optical coupling point is achieved by excitation of luminescence radiation or scattered radiation in a core of a waveguide; Figure 7 shows an embodiment of a microstructure generated at the position of the optical coupling point in the form of a dielectric free-form waveguide; Figure 8 shows an embodiment of a microstructure generated at the position of the optical coupling point in the form of a microlens; Figure 9 shows a further embodiment comprising a plurality of optical coupling points; Figure 10 shows preferred embodiments for detecting the optical radiation introduced into the optical coupling point or for coupling the light to excite the optical radiation in the interaction region of the optical coupling point; Figure 11 shows an exemplary interaction region of the coupling point of a surface-illuminated photodiode;and Figure 12 shows a preferred embodiment of an arrangement according to the invention for localizing an optical coupling point. Description of the exemplary implementations

[0052] The Figures 1A and 1BFigures 1 and 2 show schematic representations of methods for locating an optical coupling point 11, which is encompassed by an optical component 10. The coupling point 11 has an associated interaction area 15. The optical component 10 is preferably selected from the group comprising: light-guiding single-mode or multi-mode fibers made of organic or inorganic materials; semiconductor-based integrated optical chips, in particular lasers, optical amplifiers, photodiodes, superluminescent diodes or silicon photonic chips; integrated optical chips based on semiconductors or dielectric materials, preferably glasses, silicon dioxide, silicon nitride or polymers; optical circuit boards; or optical elements for free-space optics, in particular lenses, beam splitters, insulators, thin-film filters, mirrors, or diffraction gratings. The optical components can be optical waveguides with low index contrast, e.g.glass-based optical waveguides, or waveguides with medium or high index contrast, e.g., semiconductor-based waveguides. Other types of optical components 10 are conceivable, in particular filters, power dividers, or electro-optical modulators.

[0053] According to the present method, optical radiation is generated, in particular, at least in a generation area 120, wherein the generation area 120 overlaps at least partially with the interaction area 15. The generated optical radiation is detected in a detection area 130, wherein the detection area 130 also overlaps at least partially with the interaction area 15. The optical radiation generated at a selected point 16 in an overlap area between the interaction area 15 and the generation area 120 thus interacts with the optical coupling point 11, since (1) either light emitted from the optical coupling point 11 can reach the selected point 16 or (2) optical radiation that would be emitted by an isotropically radiating point light source placed at the selected point 16 can be coupled into the optical coupling point 11.

[0054] In the first case (1) the selected point of the spatial region 15 lies within a so-called "emission range" of the optical coupling point 11; in the second case within a so-called "acceptance range" of the optical coupling point 11.

[0055] In accordance with the Figures 1A and 1BFor this purpose, a medium 19 is used that at least partially fills an overlapping area of ​​the generating area 120 and the detection area 130. The medium 19 can particularly preferably comprise a substance configured to generate optical radiation from the light incident on the generating area 120. The light incident on the generating area 120 preferably serves to generate the desired optical radiation, which can in particular be scattered radiation or luminescent radiation, by means of the medium 19 within a sub-area of ​​the detection area 130. As schematically shown, the medium 19 can preferably fill an overlapping area of ​​the generating area 120, the detection area 130, and the interaction area 15 of the optical coupling point 11 to be localized, either completely or partially.

[0056] In the execution according to Figure 1AThe light for generating the optical radiation is provided by a light source 112 and emitted by the optical component 10 through the optical coupling point 11 into the interaction region 15 of the coupling point. In this case, the interaction region 15 of the optical coupling point 11 and the generation region 120 are preferably coincident, at least in the vicinity of the coupling point. At greater distances from the optical coupling point 11, it may occur that no optical radiation can be generated at a point belonging to the interaction region 15 by the light emitted by the optical coupling point 11, because the absorption or scattering of the light between the optical coupling point 11 and the point in question is too strong. The light source 112 is preferably a pulsed light source configured to generate light pulses. Alternatively, a continuous-wave light source can also be used.Determining a spatially resolved distribution of the detected optical radiation in the detection area 130 in the in . Fig. 1AThe embodiment shown is achieved using the optical system 111. For this purpose, a lens, preferably a lithography lens, can preferably be used, which performs the detection in a focal cone 60, or only in a focal point 61, or in a finite volume element surrounding the focal point 61 within the detection area 130. The position of the focal cone 60, the focal point 61, or the associated volume element can preferably be varied during the detection process by means of a beam scanner encompassed by the optical system 111, for example, in the form of a one-, two-, or three-dimensional scan. The optical radiation detected by the optical system 111 is directed to a measuring unit 110 for evaluation, which can be designed, in particular, as a power detector. Additionally or alternatively, the measuring unit 110 can comprise a camera sensor or a one-dimensional or multi-dimensional detector array.

[0057] In the execution according to Figures 1A and 1B The desired localization of the optical coupling point 11 is achieved from the spatially resolved distribution of the detected optical radiation within the detection range 130, determined by means of the measuring unit 110. For this purpose, an evaluation unit 150 is used, which is configured to determine the localization of the optical coupling point 11 from the detected spatially resolved distribution of the optical radiation.

[0058] In the embodiment according to the invention Figure 1BThe light provided by the light source 112 is emitted into the generation area 120 by means of the optical system 111 to generate the optical radiation. For this purpose, a lens, preferably a lithography lens, can preferably be used, which generates the optical radiation either in the focal cone 60 or only in a focal point 61 or in a volume element surrounding the focal point 61 within the generation area 120. In this embodiment, the spatially resolved distribution of the optical radiation in the detection area 130 is detected by the optical coupling point 11, which detects the optical radiation generated in the generation area 120, insofar as it can be coupled into the optical coupling point 11, by means of the measuring unit 110, which can be designed in particular as a power detector and which can additionally or alternatively include a camera sensor or a detector array.In this case, the interaction area 15 of the optical coupling point and the detection area 130 are preferably coincident, at least in the vicinity of the coupling point. At greater distances from the coupling point, it may occur that the optical radiation generated at a point belonging to the interaction area 15 does not reach the optical coupling point 11, or only with significant losses, because the absorption or scattering of the optical radiation between the point in question and the optical coupling point 11 is too strong.

[0059] Determining a spatially resolved distribution of the detected optical radiation in the detection area 130 is carried out in Fig. 1BThe embodiment shown is characterized by varying the position of the focal cone 60, the focal point 61, or the associated volume element within the generation area 120, preferably by means of a beam scanner encompassed by the optical system 111, during the acquisition process, for example, in the form of a one-, two-, or three-dimensional scan, while continuously determining the optical radiation acquired by the measuring unit 110. The storage and evaluation of the data and the determination of the position and orientation of the optical coupling point 11 are carried out using the evaluation unit 150, which is configured to determine the localization of the optical coupling point 11 from the acquired spatially resolved distribution of the optical radiation.

[0060] Regardless of the type of execution according to Figure 1A or 1BThe optical radiation or the light generating the optical radiation is guided in such a way that the optical radiation or the light generating the optical radiation actually passes through the optical coupling point 11. Only in this way can it be ensured that the spatially resolved distribution of the detected optical radiation actually indicates the localization of the optical coupling point 11, by relating the detected optical radiation to the optical coupling point 11 to be localized.

[0061] The localization of the optical coupling point 11 can include a specification of the position 13 and orientation 14 of the optical coupling point 11, which is in Figure 2The optical coupling point 11 is shown schematically together with its associated interaction area 15. The spatial position 13 of the optical coupling point 11 can comprise a position vector in a three-dimensional coordinate system 30, while the orientation 14 of the optical coupling point 11 can comprise one or more three-dimensional orientation vectors, one of which, for example, indicates a direction in which the light can be emitted from the optical coupling point 11 or from which efficient coupling of the light into the optical coupling point 11 is possible. It is particularly preferred that both the position vector and the orientation vector are specified in the same coordinate system 30.In the case of multiple orientation vectors, one of the orientation vectors can define a rotational orientation of the coupling point with respect to an optical axis, which is determined, for example, by the polarization of the light emitted by or detected by the coupling point.

[0062] The position 13 and orientation 14 of the optical coupling point 11 are determined by the evaluation unit 150, preferably by at least one of the following measures. A first measure can include detecting the appearance or disappearance, in particular an abrupt appearance or disappearance, of the detected optical radiation at a location within the detection range 130. A further measure can include detecting the progression, for example, the rise or fall of the detected spatially resolved distribution of the optical radiation in the detection range. A further measure can include applying a model for the optical coupling point 11, for the position-dependent coupling of the optical radiation in the generation area 120 into the optical coupling point 11, or for the distribution of the light emitted from the optical coupling point 11 to generate the optical radiation. However, other measures are conceivable.In very simple cases, such models can be based, for example, on the theory of so-called Gaussian rays, which assumes a paraxial approximation of ray propagation. Other models can employ methods of Fourier optics or the numerical description of optical field propagation.

[0063] Figure 3Figure 1 schematically shows a method in which the spatial position 13 and orientation 14 of the coupling point 11 encompassed by the optical component are detected by excitation or detection of luminescent radiation 21 in a volume element surrounding a focal point 51 of a beam 50 emitted or received by a lens 70. By spatially displacing the volume element about the focal point 51, in particular by means of a beam scanner, the spatially resolved distribution of the detected optical radiation can be determined within the detection area 120, which is at least partially filled by the medium 19. In a preferred embodiment, the lens 70 can also be used for the lithographic fabrication of microstructures. In a preferred embodiment, the detection area 120 can be at least partially filled with a substance 20 designed to generate luminescence, which assumes the role of the medium 19.This could, for example, be a photoresist that exhibits multiphoton fluorescence even when irradiated below the polymerization threshold. In the simple case of an optical waveguide 12 with a facet perpendicular to the waveguide axis, the orientation 14 of the optical coupling point 11 corresponds to an optical axis of a section of the optical waveguide 12 adjoining the optical coupling point 11. The excitation of the luminescence radiation 21 can occur either through the optical coupling point 11 or through the lithography objective 70.

[0064] Figure 4Figure 1 schematically shows a further embodiment of the present method, in which the spatial position 13 and orientation 14 of the coupling point 11 encompassed by the optical component are detected by excitation or detection of scattered radiation 26 in a volume element surrounding the focal point 61 of a beam 60 emitted or received by a lens 70. With regard to a local displacement of the volume element, particularly within the context of a one- or multi-dimensional scanning process, the description in section 2 applies. Figure 3As stated above. Here too, in a preferred embodiment, the lens 70 can also be used for the lithographic fabrication of microstructures. The scattered radiation 26 can preferably be generated by means of scattering centers 27, which scatter the light incident on the volume element 61 in such a way that the scattered radiation thereby generated can be at least partially detected. In the simple case of an optical waveguide 12, the orientation 14 of the optical coupling point 11 corresponds to an optical axis of a section of the optical waveguide 12 adjoining the optical coupling point 11. The excitation of the scattered radiation 21 can be carried out either through the optical coupling point 11 or by means of the lithography lens 70.

[0065] In a further version according to Figure 5The optical coupling point 11 is not located on a surface of the optical component 10, but is, by way of example, arranged offset from the surface of the optical component 10 by a distance d. This case can occur, for example, with a facet of the waveguide 12 that has a deflection by a distance d relative to a chip edge 18. In this case, a tip of the conical space region 15 lies within the optical component 10. The medium 19 is in direct contact with the surface of the optical component. The position of the chip edge 18 relative to the position of the optical coupling point 11 can be determined in this case by an abrupt disappearance or a sudden drop in the detected optical radiation at the chip edge 18.

[0066] Figure 6Figure 1 shows a further embodiment in which the position 13 and orientation 14 of the optical coupling point 11, formed by the waveguide 12 of the optical component 10, are detected by excitation of luminescence radiation 21 in a waveguide core 17 of the waveguide 12 itself. In this case, the waveguide core 17 preferably comprises a substance configured to generate the luminescence radiation 21. Additionally or alternatively, the waveguide core 17 can comprise another substance configured to generate scattered radiation (not shown).

[0067] The Figure 7 and 8 schematically show microstructures 100 generated at an optical coupling point using the present method for generating a microstructure, which have a precise alignment at the optical coupling point 11 with respect to position 13 and orientation 14.

[0068] Figure 7Figure 1 shows a microstructure 100 generated at position 13 of the optical coupling point 11 in the form of a dielectric free-form waveguide 101, also known as a "photonic wire bond", wherein the dielectric free-form waveguide 101 is aligned with respect to position 13 and orientation 14 of the optical coupling point 11.

[0069] Figure 8Figure 1 shows a further microstructure 100 in the form of a microlens 102, which is located at a further optical coupling point 211 formed by a further optical waveguide 212 of a further optical component 210, wherein the further optical coupling point 211 is not in direct contact with the already described optical coupling point 11, which is encompassed by the optical component 10. The position 213 and orientation 214 of the further optical coupling point 211 can also be used to design the microstructure 100. The microstructure 100 is designed based on the positions 13, 213 and the orientations 14, 214 of the two optical coupling points 11, 211 such that efficient coupling between the two optical coupling points 11, 211 is achieved. In addition to the embodiment according to Figure 10, the following further embodiments are also shown: Figure 8For efficient coupling, it may also be advantageous to create microstructures 100 at both optical coupling points 11, 211, whereby the position and orientation of both optical coupling points 11, 211 are used to design each of the microstructures 100.

[0070] Figure 9 Figure 1 shows a further embodiment in which a plurality of optical coupling points 11 are defined by facets of the waveguide cores 12 of a multi-core fiber. In this embodiment, for example, the total optical radiation coupled into all fiber cores can be integrally determined by the common measuring unit 110, whose active area extends over all waveguide cores of the multi-core fiber.

[0071] Figure 10Figure 1 schematically shows various preferred embodiments for detecting the optical radiation introduced into the optical coupling point 11 of the optical component 10, or for coupling in the light suitable for exciting the optical radiation in the interaction area 15 of the optical coupling point 11. Other embodiments, not shown here, are also possible.

[0072] In the execution according to Figure 10A The optical component 10 can comprise the light source 112 or the measuring unit 110, wherein the light source 112 or the measuring unit 110 has an optical connection with the optical coupling point 11 to be located.

[0073] In the execution according to Figure 10B For this purpose, the light source 112 or the measuring unit 110 can be arranged outside the optical component 10 and comprise a connection with the optical component 10, preferably in the form of an optical waveguide or a fiber optic cable.

[0074] In the execution according to Figure 10CThe optical component 10 can have coupling structures 113, e.g., in the form of so-called grating couplers, with which light or the detected optical radiation can be coupled out of or into the optical component 10. The coupled-in light or coupled-out optical radiation can be detected or provided either by the lithography lens 70 itself, by another lens (not shown), or by another optical element, preferably an optical fiber, or a light source, preferably a photodiode (not shown). The grating couplers can be designed to have a high coupling efficiency for the wavelength of the light or associated optical radiation transmitted within the scope of the present method, while not affecting, or only minimally affecting, optical signals at the operating wavelength of the optical component 10.

[0075] In the execution according to Figure 10D Scattered or luminescent radiation occurring within the waveguide 12 can be detected, preferably by means of the lens 70 itself or by means of a further lens. The generation of scattered radiation can be achieved here by suitable scattering structures, for example based on periodic structures. These structures can be designed such that they exhibit a high scattering efficiency for the wavelength of the light transmitted within the scope of the present method, while they do not affect, or only minimally affect, optical signals at the operating wavelength of the optical component 10.

[0076] Figure 11Figure 1 shows an example of the interaction area 15 of a surface-illuminated photodiode 105. The optical coupling point 11 corresponds here to an active surface 106 of the photodiode 105, while the normal vector of the active surface 106 of the photodiode 105 is usually considered to be the orientation of the optical coupling point 11.

[0077] Figure 12Figure 1 schematically shows a preferred embodiment of an arrangement 200 according to the invention for localizing the optical coupling point 11 in the optical component 10, which is arranged on an optical table 108 that is movable in the x, y, and z directions. The arrangement 200 is based on a three-dimensional laser lithography system with rapid beam deflection by a beam scanner 132, preferably in the form of a so-called "galvo scanner," which has been extended by additional detection channels for the optical radiation. The light source 112 comprises a femtosecond laser, which has an emission wavelength of 780 nm, a pulse duration of approximately 100 fs, and a repetition rate of approximately 100 MHz.To implement the method for localizing the optical coupling point 11, the fluorescence radiation 21 is generated by means of multiphoton excitation, whereby the light used for excitation is partially directed through the beam path of the lithography system into the generation area 120. The light used for excitation can be generated either by the same light source 112 that is also used for lithographic structuring, or by an additional light source that can be coupled into the beam path via another beam splitter (not shown). A photoresist serves as the medium 19, to which fluorescent dyes can also be added.To localize the optical coupling point 11, selected parameters, in particular the power, wavelength, and / or pulse duration of the light irradiated into the medium 19, are adjusted such that the dose introduced is preferably below the dose threshold for undesirable polymerization during detection. A portion of the fluorescence radiation 21 generated within the generation area 120 couples into the optical coupling point 11. In the present embodiment, the optical component comprises at least one optical waveguide 12, for example in the form of an optical fiber, which includes at least one waveguide core 17. The waveguide 12 is connected to the measuring unit 110, which here is in the form of a photoamplifier. photo multiplier tube)can be implemented, and which measures the fluorescence radiation 21 coupled into the at least one waveguide core 17 as a function of the spatial position of the focal point of the lithography system used for excitation. In the case of a multi-core fiber, the sum of the fluorescence radiation 21 coupled into the different waveguide cores 17 can be determined according to Figure 9 integrally recorded by means of the measuring unit 110 in the form of a photoamplifier.

[0078] Alternatively, the light source 112, suitable for exciting the optical radiation, can be connected to at least one of the waveguide cores 17 (not shown). The optical radiation is then detected by the objective 70 and fed via an arrangement designated as a fluorescence path 115 to a further measuring unit 110' in the form of a photoamplifier. In this embodiment, the entire fluorescence path 115 is formed by the objective 70 and the lenses and beam splitters upstream of it, and can additionally include the beam scanner 132. The time-resolved signal from the measuring units 110 and 110' is digitized. From the focus positions set by the beam scanner 132 and thus known in all three spatial directions, the detected optical radiation can be determined with spatial resolution, and from this, the orientation and position of the at least one waveguide core 17 can be determined.

[0079] Furthermore, as in Figure 12schematically represented, the arrangement comprises 200 further optical, optoelectronic or electronic elements, in particular further measuring units 110, light sources 112, lenses, mirrors, beam splitters or filters.

[0080] The arrangement 200 was successfully used to measure the position 13 and orientation 14 of the optical coupling point 11 of single-core and multi-core fibers. The aim of one embodiment was to detect the coupling points 11 of a seven-core fiber. In contrast to conventional single-core fibers, multi-core fibers are not symmetrical with respect to any rotation about a fiber axis, so that the position 13 of the waveguide cores 17 usually remains undefined after their assembly. To detect the waveguide cores 17, multiphoton fluorescence radiation was excited by the lithography lens 70 in a volume located upstream of an end facet of the multi-core fiber and integrally detected over all seven waveguide cores 17 by the measuring unit 110 connected to the multi-core fiber in the form of a photoamplifier.To measure the spatially resolved distribution of the fluorescence radiation, the excitation light beam was first moved laterally in a focal plane of the lithography objective 70 using the beam scanner 132. Furthermore, the focal plane itself was moved relative to the optical multicore fiber by means of an axial displacement of the objective in the z-direction using the objective drive 135. From the three-dimensionally spatially resolved distribution of the fluorescence radiation detected by the multicore fiber, the position 13 and the orientation 14 of the optical coupling points 11 assigned to the individual waveguide cores 17 can be determined. Additionally, a portion of the excited fluorescence radiation can be detected by the lithography objective 70 itself and used for imaging.The recorded measurement data in the evaluation unit 150 can be used both to determine the topology of the optical component 10 and to arrive at a more refined determination of the position 13 and the orientation 14 of the optical coupling point 11.

[0081] The in Figure 12The arrangement shown, in a slightly modified form, can also be used to implement the method for generating a microstructure (not shown here) at the optical coupling point 11. For this purpose, the parameters, in particular the wavelength, the power, or the pulse duration of the light emitted by the light source 112, can be varied such that polymerization of a photoresist in a spatial element in the vicinity of the focal point of the lithography beam becomes possible. By moving the focal point while simultaneously varying the incident light, spatially selectively solidified volume regions can be generated, which together form the desired microstructure. The polymerization can be based on single- or multi-photon absorption processes.In a particular embodiment, the light source can include a femtosecond laser whose output power can be varied either directly or by means of an external modulator, preferably an acousto-optic modulator. Additionally, the light source can include an adjustable pulse compressor with which the pulse duration of the light emitted into the photoresist can be varied.

[0082] In a representation of the distribution of the two-photon fluorescence power detected through the multi-core fiber in a plane at the level of the central waveguide core 17 perpendicular to the z-direction, which corresponds to the direction along the optical axis of the lithography objective 70, the fluorescence can drop off abruptly at the interface between the medium 19 and the fiber facet, since no excitation of two-photon fluorescence is possible within the optical component 10. This abrupt drop in the detected optical radiation can be used to precisely localize the fiber facet serving as the optical coupling point 11. By acquiring a stack of images at different z-positions, a three-dimensionally spatially resolved detection of the two-photon fluorescence over a volume can be achieved.This also enables virtual sections in planes perpendicular to an axis of the multi-core fibers, in which the seven cores of the multi-core fiber are clearly visible. Particularly noteworthy is that the cross-section of the fiber cores can be precisely derived from the distribution of the luminescence radiation 21 directly at the optical coupling point 11. Additionally, a spatial distribution of the portion of the luminescence radiation 21 captured by the lithography lens 70 itself can be captured analogously in an image stack from different focus heights, revealing the topology of the fiber but not the positions 13 of the respective coupling points 11. Reference symbol list

[0083] 10, 210 Optical component 11, 211 Optical coupling point 12, 212 Optical waveguide (fiber) belonging to the coupling point 13, 213 Position of the coupling point 14, 214 Direction of the coupling point 15 Interaction area of ​​the coupling point 16 Point in the overlap area 17 Waveguide core 18 Chip edge 19 Medium (interaction medium) 20 Substance designed to generate luminescence 21 Luminescence radiation (fluorescence radiation) 25 Substance designed to generate scattering 26 Scattered radiation 27 Scattering center 30 Coordinate system 40 Generated microstructure 50 Focused laser beam for generating luminescence 51 Focus point 60 Imaging focus cone of the lithography lens 61 Focus point 70 Lens (Lithography lens) 100 Microstructure 101 Aligned dielectric waveguide 102 Aligned microlens 105 Surface-illuminated photodiode 106 Active area of ​​the surface-illuminated photodiode 108 Optical stage 110110'Measuring unit 111Optical system for generating or detecting optical radiation 112Light source (pulsed light source) 113Coupling structure 114Scattering through the waveguide 115Fluorescence path 120Detection area of ​​optical radiation 130Generation area of ​​optical radiation 132Beam scanner 135Objective drive 150Evaluation unit 200Arrangement for locating an optical coupling point,

Claims

1. Method for localizing an optical coupling point (11), comprising the following steps: a) providing an optical component (10) comprising an optical coupling point (11), wherein the optical coupling point has an interaction region (15) located outside a volume encompassed by the optical component (10); b) producing optical radiation in a production region (120), wherein the production region (120) at least partly overlaps with the interaction region (15) of the optical coupling point (11), wherein light impinges on a medium (19) located in the production region (120), said light being modified by the medium (19) in such a manner that the optical radiation is thereby produced; c) capturing at least one part of the produced optical radiation in a capture region (130), wherein the capture region (130) at least partly overlaps with the interaction region (15) of the optical coupling point (11), and ascertaining a spatially resolved distribution of the captured part of the produced optical radiation; and d) determining the localization of the optical coupling point (11) from the ascertained spatially resolved distribution of the captured part of the produced optical radiation, characterized in that capturing at least the part of the produced optical radiation is effected through the optical coupling point (11).

2. Method according to the preceding claim, wherein the medium (19) comprises scattering centers (27), wherein the scattering centers (27) produce scattered radiation (26).

3. Method according to claim 1, wherein the medium (19) comprises a luminescent substance (20) or a photoinitiator that forms the luminescent substance (20), wherein the luminescent substance (20) produces luminescence radiation (21).

4. Method according to the preceding claim, wherein the luminescence radiation (21) is produced by excitation of a multi-photon absorption process in the luminescent substance (20).

5. Method according to either of the two preceding claims, wherein the medium (19) furthermore comprises a photoresist, wherein a dose that is below a dose threshold for polymerization of the photoresist is introduced into the photoresist for a purpose of producing the optical radiation.

6. Method according to any one of the preceding claims, wherein capturing the optical radiation or radiating the light for producing the optical radiation in the production region (120) is effected through an objective (70), wherein the objective (70) has a numerical aperture of at least 0.3.

7. Method according to any one of the preceding claims, wherein the radiating of the light into the production region (120) or the capture of the produced optical radiation in the capture region (130) is spatially altered, and wherein capturing the spatially resolved distribution of the optical radiation is effected through the optical coupling point (11).

8. Method according to the preceding claim, wherein the spatial change of the radiating of the light into the production region (120) or the capture of the produced optical radiation in the capture region (130) is effected by using a beam scanner (132).

9. Method according to any one of the preceding claims, wherein the localization of the optical coupling point (11) comprises an indication of position (13) and orientation (14) of the optical coupling point (11), wherein the position (13) and the orientation (14) of the optical coupling point (11) are determined by at least one of the following measures: - verifying an appearance or a disappearance of the captured optical radiation at a location within the capture region (130); - evaluating the spatially resolved distribution of the captured part of the produced optical radiation in the capture region (130); - applying a model for the optical coupling point (11), for a position-dependent input coupling of the optical radiation in the production region (120) into the optical coupling point (11) or for a distribution of the light emitted from the optical coupling point (11) for the purpose of producing the optical radiation.

10. Method for producing a microstructure (100) at an optical coupling point (11) of an optical component (10), comprising the following steps: i) localizing an optical coupling point (11) in accordance with the method according to any one of the preceding claims; and ii) producing a microstructure (100) at the optical coupling point (11) by using a manufacturing method selected from an additive manufacturing method or a subtractive manufacturing method.

11. Method according to the preceding claim, wherein one objective (70) is used both for localizing the optical coupling point (11) and for producing the microstructure (100) at the optical coupling point (11), wherein the objective has a numerical aperture of at least 0.3.

12. Arrangement (200) for localizing an optical coupling point (11), comprising - an optical component (10) comprising at least one optical coupling point (11), wherein the optical coupling point has an interaction region (15) located outside a volume encompassed by the optical component (10); - an optical device configured for producing optical radiation in a production region (120) and / or for capturing at least one part of the produced optical radiation in a capture region (130), wherein the production region (120) and the capture region (130) at least partly overlap with the interaction region (15) of the optical coupling point (11); and - an evaluation unit (150) configured for ascertaining a spatially resolved distribution of a captured part of the optical radiation and for determining the localization of the optical coupling point (11) from the ascertained spatially resolved distribution of the captured part of the optical radiation, Characterized in that the arrangement is configured in such a manner that capturing at least the part of the produced optical radiation is effected through the optical coupling point (11).

13. Arrangement (200) according to the preceding claim, wherein the optical device comprises a light source (112) configured for producing light which, upon impinging on a medium (19) located in the production region (120), is modified by the medium (19) in such a manner that the optical radiation is thereby produced.

14. Arrangement (200) according to either of the two preceding claims, wherein the optical device furthermore comprises a beam scanner (132) configured for effecting a spatial change of the radiating of the light into the production region (120) or of the capture of the produced optical radiation in the capture region (130).

15. Arrangement (200) according to any one of the three preceding claims, wherein the optical device is furthermore configured for producing a microstructure (100) at the optical coupling point (11).