Method for producing a slab waveguide for non-linear integrated optics
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
- Filing Date
- 2024-08-07
- Publication Date
- 2026-07-08
Smart Images
Figure EP2024072347_06032025_PF_FP_ABST
Abstract
Description
[0001] Fraunhofer Society for the Promotion of Applied Research
[0002] Hansastraße 27c, 80686 Munich, Germany
[0003] Method for producing a layered waveguide for nonlinear integrated optics
[0004] The invention relates to a method for producing a layered waveguide for non-linear integrated optics according to the features of the preamble of claim 1 and a layered waveguide for non-linear integrated optics according to the features of the preamble of claim 10.
[0005] For many applications in photonic quantum technology, waveguide materials with high Nonlinearities of large
[0006] Interest, whereby represents the electrical susceptibility with order n = 2 or 3. In conventional photonic devices, nonlinearities are used, for example, for (electro-)optical phase modulation, frequency conversion, or supercontinuum generation. Furthermore, these materials can be used in quantum photonic applications to generate entangled photon pairs. The disadvantages of such waveguides are their high absorption and poor waveguiding properties.
[0007] Silicon (Si) or silicon nitride waveguide platforms, which have low absorption and good waveguiding properties, are established in the photonics industry. The disadvantage of these waveguides is that they exhibit only low optical nonlinearities. The present invention is based on the object of developing a method for producing layered waveguides with high nonlinearities and simultaneously improved waveguiding properties and corresponding layer waveguides with high nonlinearities while providing improved waveguiding properties.
[0008] The object is achieved according to the invention by a method for producing a layer waveguide for nonlinear integrated optics according to the features of claim 1.
[0009] According to the invention, a method for producing a layered waveguide for non-linear integrated optics is proposed, comprising the steps: i) providing a carrier substrate with one or more carrier substrate layers, wherein the one or the uppermost carrier substrate layer has a refractive index n Tii) applying a plurality of waveguide layers one above the other to the carrier substrate; iii) structuring the layer waveguide by lateral structuring of at least one waveguide layer; wherein the application of one or more waveguide layers in ii) and the shaping of at least one waveguide layer in iii) takes place a) successively or b) alternately.
[0010] It is essential that in step ii) at least one optically non-linear layer and above and / or below at least one high-index layer with a refractive index n H be applied, where n H > n T applies.
[0011] Furthermore, the object is achieved by a layer waveguide for non-linear integrated optics according to the features of claim 10. According to the invention, a layer waveguide for non-linear integrated optics is proposed, comprising: a carrier substrate with one or more carrier substrate layers, wherein the one or the uppermost carrier substrate layer has a refractive index n T and at least two waveguide layers arranged on the carrier substrate, wherein the layer waveguide is formed by at least one of the waveguide layers.
[0012] It is essential that the waveguide layers have at least one optically non-linear layer and above and / or below at least one high-index layer with a refractive index n H where n H > n T applies.
[0013] One advantage achieved by the invention relates to the improvement of the waveguiding properties of waveguides functionalized with an optically nonlinear layer, for example, made of silicon (Si) or silicon nitride, through lower radial radiation and lower absorption, while simultaneously increasing the nonlinear efficiencies achieved in the waveguides by improving the overlap of the highest mode intensities with the nonlinear functionalization. The nonlinear response of the waveguide is preferably caused solely or predominantly by the optically nonlinear layer.
[0014] In particular, the invention enables the production of smallest, low-loss components with improved, optimized efficiency in electro-optical modulation and improved spontaneous nonlinear conversion processes such as four-wave mixing and downconversion. Furthermore, the method is characterized by simple industrial integration and scalability of the process steps required to realize waveguides functionalized with optically nonlinear layers. The method according to the invention and the layer waveguide according to the invention make it possible to achieve the high Nonlinearities of the nonlinear layer to determine the effective Nonlinearities in
[0015] Waveguide architectures with simultaneously improved waveguiding properties. This makes layered interconnections and derived optical components feasible, which have higher effective / (2) , have nonlinearities in combination with good waveguiding properties (mode confinement).
[0016] The geometry of the layer waveguide according to the invention, preferably produced by the method according to the invention, enables an overlap of the mode guided in the layer waveguide with the optically nonlinear layer in order to make its optical properties efficiently usable in photonic circuits.
[0017] At least one waveguide layer or one or more waveguide layers can be understood as just one layer, two layers, three layers, four layers, five layers, or more than five layers. This also applies to the at least one optically nonlinear layer and the at least one high-index layer with a refractive index n. HMultiple waveguide layers are understood to mean two, three, four, five, or more than five waveguide layers. Preferably, a maximum of 10,000 waveguide layers are deposited or formed on top of one another.
[0018] Applying one above the other is understood here as a flat application of the layers in contact with one another. Applied above and / or below, or applied above and / or below, is understood here as flat layers that are applied one above the other in contact and arranged in such a way. The a) successive steps of applying several waveguide layers in ii) and forming at least one waveguide layer in iii) are understood, for example, to mean that first several waveguide layers in ii) are applied to the carrier substrate and then at least one waveguide layer is formed in iii).
[0019] The b) alternating steps of applying a plurality of waveguide layers in ii) and forming at least one waveguide layer in iii) are to be understood, for example, as meaning that first one or more waveguide layers in ii) are applied to the carrier substrate, from this one or more waveguide layers at least one waveguide layer is or are subsequently formed in iii), and then one or more further waveguide layers is or are applied in ii), which can preferably then be formed in a further step iii).
[0020] Underneath at least one optically non-linear layer and above and / or below at least one high-index layer with a refractive index n Hare applied is to be understood that in step ii) as waveguide layers at least one optically non-linear layer and above or below at least one high-index layer with a refractive index n H are applied, or that in step ii) as waveguide layers at least one optically non-linear layer is applied between at least one high-refractive index layer with a refractive index n H be applied.
[0021] Thus, for example, at least one optically non-linear layer and above it at least one high-refractive layer with a refractive index n H be applied or arranged. Furthermore, for example, at least one optically non-linear layer and, underneath, at least one high-index layer with a refractive index n Hbe applied or arranged. Furthermore, for example, at least one optically non-linear layer can be arranged between at least one high-index layer with a refractive index n H be applied or arranged. Furthermore, for example, at least one optically non-linear layer and at least one high-index layer with a refractive index n H be applied or arranged several times one above the other alternately.
[0022] Underneath at least one optically non-linear layer and above and / or below at least one high-index layer with a refractive index n H It is to be understood that the waveguide layers have at least one optically non-linear layer and above or below at least one high-index layer with a refractive index n Hor that the waveguide layers have at least one optically non-linear layer between at least one high-refractive index layer with a refractive index n H have.
[0023] It can be provided that the application of the one or more waveguide layers in step ii) and / or the formation, i.e. the lateral structuring, of one or more waveguide layers in step iii) takes place based on the selection of the modes and / or wavelengths to be transported. The application influences the thickness of the layer waveguide, wherein the structuring influences the width of the layer waveguide. By adjusting the thickness and width of the layer waveguide, a high transmission of the desired mode(s) for the desired wavelength(s) can be achieved. It can be provided that the layer waveguide is designed for wavelengths in the range between 200 nm and 2000 nm, preferably in the range from 300 nm to 900 nm and / or 1200 nm to 1600 nm.
[0024] It can be provided that the application of the one or more waveguide layers in step ii) and / or the formation of the one or more waveguide layers in step iii) is determined by numerical simulations and / or analytical calculations, taking into account the wavelength(s) of the mode(s) to be guided. The numerical simulation and / or analytical calculations can easily adapt the layers constituting the layer stack, the width of the waveguide to be structured, and preferably the thickness of a cladding layer to the wavelength of the mode to be guided in such a way that the mode properties, such as minimal radiation losses and absorption, are combined with the highest light intensity in the optically nonlinear layer located in the waveguide.
[0025] It can be provided that the thickness and / or width of the waveguide layers, and preferably the thickness of the cladding layer, is adapted to the mode properties corresponding to the wavelength of the mode to be guided, by combining the mode properties with the highest light intensity in the optically nonlinear layer located in the layered waveguide. Mode properties include, for example, the radiation losses and absorption in the layered waveguide. This makes it possible to provide layered waveguides with low radiation losses and low absorption.
[0026] It can be provided that in step iii) at least one high-refractive index layer is formed above and below the at least one optically non-linear layer. It can be provided that at least one high-refractive index layer above and below the at least one optically non-linear layer is designed as a layer waveguide. Such a shaping and design is advantageous for guiding the fundamental mode of the wave to be transported. The advantage of a symmetrical design, i.e. an optically non-linear layer between at least one high-refractive index layer, is that the radiation of modes in a direction perpendicular to the direction of propagation in the waveguide is greatly reduced.Furthermore, such a design is advantageous in that the waveguide mode has a significant overlap with the nonlinear material, allowing, for example, a relatively thin optically nonlinear layer to be used while simultaneously achieving high optical nonlinearity. Another advantage is that the nonlinearity is not introduced solely by evanescent coupling, which significantly improves the enhancement of the nonlinear properties of the waveguide.
[0027] It can be provided that in step iii), the at least one high-index layer is formed above or below the optically nonlinear layer and the at least one optically nonlinear layer. It can be provided that the at least one high-index layer and the at least one optically nonlinear layer are designed as a layer waveguide. Such a shaping and configuration is advantageous for higher-mode waves to be transported, which usually have a higher evanescent field compared to the fundamental mode. Evanescence is the effect that optical waves penetrate a material in which they cannot propagate and decay exponentially beneath its surface.
[0028] It may be provided that the forming in step iii) is carried out by lithography such as imprint lithography, UV lithography, focused ion beam milling, laser lithography, two-photon lithography or electron beam lithography, and wet or dry etching. It may be provided that the refractive index n H the high-index layer n H > 1.8 applies, preferably a maximum of 10. It can be provided that for the refractive index n T the topmost carrier substrate layer n T < 1.8 applies, preferably at least 1. It can be provided that for the refractive index a sheath < 1.8 applies, preferably at least 1. It is also important that n H > n T It can be provided that the refractive index n H at least by 0.05, preferably at least by 0.1 of the refractive indices n T A larger distance allows for better mode guidance and waveguiding, while at the same time achieving a higher level of nonlinearity. The refractive index of the optically nonlinear layer can be smaller, equal to, or greater than the refractive index n H the high-index layer. If the refractive index n H smaller than the refractive index of the non-linear layer, it is advantageous if the optically non-linear layer is thin, preferably in the nm range, in order not to influence the mode guidance in the waveguide too strongly.
[0029] It can be provided that the carrier substrate is formed from one or more of the following materials and / or is provided in step i): silicon (Si), and / or silicon dioxide (SiO2), and / or sapphire, and / or III / V and II / VI semiconductors. The advantage of the materials silicon (Si) and silicon dioxide (SiO2) is that these materials represent CMOS-compatible waveguide material platforms.
[0030] It can be provided that the carrier substrate has a first carrier substrate layer made of silicon (Si) and is coated with a low-refractive-index material with low optical absorption, preferably silicon dioxide SiC>2, as a second carrier substrate layer. The advantage of this configuration is that only the uppermost layer is made of low-refractive-index material with low optical absorption, which leads to simpler production and lower costs. By applying a low-refractive-index material to a first carrier substrate layer made of silicon (Si), silicon (Si) can subsequently also be used as one or more of the waveguide layers. This makes it possible to achieve high transmission and simple production of the layer waveguide.
[0031] Under at least one optically non-linear layer there is one or more layers of material with high Understanding nonlinearities.
[0032] Nonlinear optical effects only occur in materials where the terms with susceptibilities of order greater than or equal to 2 do not vanish, i.e., are not equal to or approximately zero. Preferably, the susceptibility of order 2 and / or 3 of the optically nonlinear layer is greater than the susceptibility of order 2 and / or 3 of the high-index layer with a refractive index n H .
[0033] It can be provided that the optically non-linear layer is thinner than the at least one high-refractive-index layer, preferably thinner than the at least one formed high-refractive-index layer, preferably smaller than the height, preferably smaller than half the height, of the at least one high-refractive-index layer.
[0034] It can be provided that the optically nonlinear layer in step ii) is applied with a thickness in the nm range or in the range of the wavelength(s) of the mode(s) to be guided. It can be provided that the optically nonlinear layer is formed with a thickness in the nm range or in the range of the wavelength(s) of the mode(s) to be guided. The optimal thickness of the optically nonlinear layer depends on the desired application and can vary greatly depending on the material properties and the underlying waveguide geometry. For example, a greater thickness can result in greater nonlinearity but can also contribute to increased absorption of the mode guided in the layer waveguide. Thus, nonlinear, high-refractive-index and low-absorbing materials can assume a waveguiding function within the waveguide design and be approximately as thick as high-refractive-index layers.More strongly absorbing or less highly refractive optically nonlinear materials, on the other hand, should make up smaller portions of the waveguide to avoid excessively influencing mode guidance within the waveguide design. This allows the optical design of the waveguide to be flexibly adapted to different optically nonlinear materials intended for functionalization.
[0035] The optically nonlinear layer can be designed as a crystalline or amorphous layer. Amorphous layers have a disordered and non-crystalline structure. They are inexpensive to produce but usually have a lower efficiency than a crystalline layer.
[0036] It can be provided that the optically non-linear layer is formed from one or a combination of the following materials and / or is applied in step ii):
[0037] Metal oxide, preferably tellurium dioxide (TeO2), and / or mixed oxide, preferably indium tin dioxide (In2O3:SnO2 / ITO) or aluminum zinc dioxide (Al2O3:ZnO2 / AZO) which have high / ® nonlinearities, and / or nanoscale layer systems of oxides such as so-called nanolaminates, preferably zinc oxide (ZnO), titanium dioxide (TiO2) and / or silicon dioxide (SiO2), and / or ternary oxides / perovskites, preferably barium titanate (BaTOs) and / or lithium niobate (LiNbOs), and / or other non-centrosymmetric crystals such as gallium phosphide (GaP), and / or beta-barium borate (BBO), and / or potassium titanyl phosphate (KTP), and / or potassium dihydrogen phosphate (KDP), and / or zinc oxide (ZnO), and / or III / V Semiconductors, and / or II / VI semiconductors, and / or perovskites, and / or chalcogenide glasses which are not centrosymmetric and therefore show high second-order nonlinearities ( / ®), and / or 2D materials, preferably graphene, and / or transition metal dichalcogenides, preferably M0S2, MoSe2, WS2,WSe2, which are characterized by high / ® nonlinearities and can be encapsulated in layers for integration with waveguide structures. In addition to high / ®, ® nonlinearities, oxides and oxide nanolaminates also exhibit crucial properties for industrial usability, such as high chemical stability, good availability (low costs, short supply chains), and CMOS compatibility. This means they can be integrated into established industrial process chains and are thus ideally suited for the nonlinear hybridization of established waveguide platforms.
[0038] It can be provided that in step ii), the optically nonlinear layer is formed from an optically linear material or from a combination of optically linear materials and / or is applied in step ii), which exhibit nonlinear optical properties due to a symmetry break in the crystal structure at the interface with the high-index layer or at the interfaces between them. This allows for fine-tuning of the nonlinear effects with simultaneous low absorption.
[0039] It can be provided that in step ii) the optically nonlinear layer is applied as a layered nanolaminate. It can be provided that the optically nonlinear layer is formed as a layered nanolaminate. A layered nanolaminate consists of several thin layers of one or more of the aforementioned materials of the optically nonlinear layer. By combining different materials at the nanoscale level, optically nonlinear nanolaminates enable the control of light interactions, such as frequency doubling and parametric amplification. This enables the development of compact, energy-saving optical components for signal processing, imaging, and communication. The precise adaptation of the layer thicknesses and materials allows the fine-tuning of the nonlinear effects and enables customized solutions for specific applications in photonics.
[0040] It can be provided that the optically nonlinear layer is applied by layer deposition, preferably in step ii), preferably by physical deposition processes such as evaporation, sputtering, ion beam deposition or ion beam epitaxy, or by chemical vapor deposition (CVD), or by atomic layer deposition, or micro-transfer jetting, micro-transfer printing, or wafer bonding, and other processes. For the application of the layered nanolaminate, it is possible to produce the components both in a single combined process and in successive separate deposition processes. If the application is carried out in separate processes, the surfaces must be protected from any physical or chemical changes between the individual steps to avoid undesirable influences.
[0041] It can be provided that the high-index layer with a refractive index n His formed from one or more of the following materials and / or is applied in step ii): silicon nitride (Si3N4), titanium dioxide (TiO2), amorphous silicon (aSi), hafnium oxide (HfO2), tantalum oxide (Ta2Os) and / or silicon (Si). It is essential that the refractive index n H the high-index layer is greater than the refractive index n T of the substrate material. For example, silicon (Si), titanium dioxide (TiO2) or silicon nitride (Si3N4) have a higher refractive index (n H> 1.8) than, for example, SiO2. While silicon (Si) has a very high refractive index (approx. 3.5), low absorption, and correspondingly good waveguiding in the near-infrared (NIR) range, silicon nitride (Si3N4) has a high refractive index (approx. 2.0), low absorption in the visible (VIS) to near-infrared (NIR) range, and correspondingly good waveguiding properties in a wider spectral range. Titanium dioxide (TiO2) has a very high refractive index (approx. 2.7) and low absorption in the visible (VIS) to near-infrared (NIR) range, combining the advantages of silicon nitride (Si3N4) and silicon (Si).
[0042] It can be provided that the high-index layer is applied by layer deposition, preferably in step ii), preferably by physical deposition processes such as evaporation, sputtering, ion beam deposition or ion beam epitaxy or by chemical vapor deposition, or atomic layer deposition, or micro-transfer jetting, micro-transfer printing or wafer bonding and other processes.
[0043] It may be provided that after step iii) the following step iv) is carried out: iv) Cladding the layer waveguide with a material with refractive index n^, where n H It can be provided that the layer waveguide is made of a material with refractive index n^, where n H > coated. A material with a refractive index of The advantage of a cladding is the better transmission of the waveguide through the material used with refractive index and also serves as protection against external influences.
[0044] It can be provided that the material of the uppermost carrier substrate layer with a refractive index n T is used, ie n T = This allows a waveguide with particularly good symmetrical conduction properties to be formed.
[0045] It can be provided that the application of one or more waveguide layers in ii), the shaping of at least one waveguide layer in iii) and the cladding of at least one waveguide layer in iv) take place a) one after the other or b) alternately. In such a further development according to method a), it can be provided that after the application of the one or more waveguide layers in step ii) and after the shaping in step iii), the layer waveguide is cladding on its side surfaces and / or its top side in step iv). It can be provided that the layer waveguide is cladding on its side surfaces and / or its top side. This ensures improved transmission and additional protection from all sides against external influences.
[0046] In such a further development according to method b), it can be provided that after the application of the one or more waveguide layers in step ii) and after the formation of the one or more waveguide layers in step iii), these formed one or more waveguide layers are completely or at least partially, preferably laterally, encased in step iv) and then a further one or more waveguide layers are applied to the formed waveguide layer and the encasement in a step ii). The subsequently applied further waveguide layers can be formed or not formed in a further step iii) and / or encased or not encased in a further step iv).This allows layer waveguides to be manufactured from a wide variety of materials, whereby, for example, an optically non-linear layer can be applied over a large area to a shaped high-refractive-index layer and a layer cladding it laterally.
[0047] In addition to the thickness and / or width of the waveguide layers, the thickness of the cladding layer can be adapted to the mode properties corresponding to the wavelength of the mode to be guided, by combining the mode properties with the highest light intensity in the optically nonlinear layer located within the layered waveguide. The layered waveguide can be used for nonlinear parametric processes, preferably second-order nonlinear processes or third-order nonlinear processes. This allows the layered waveguide to be used universally for a wide range of nonlinear processes.
[0048] In the case of a second-order nonlinear process, it may be a process of sum frequency generation, second harmonic generation, difference frequency mixing, spontaneous parametric generation, rectification and / or electro-optical modulation.
[0049] In the case of a third-order nonlinear process, it can be considered to be a process of self-phase modulation, supercontinuum generation, cross-phase modulation, four-wave mixing, and / or spontaneous four-wave mixing.
[0050] The thickness and / or width of the layered waveguide can be adapted to the frequency range of a pump wavelength and / or to the frequency range of the nonlinear polynomial response. By adapting to the frequency range of the pump wavelength, very efficient pumping of the nonlinear process can be achieved. By adapting to the frequency range of the nonlinear polynomial response, a high transmission of the resulting photons can be achieved.
[0051] Further embodiments of the invention are illustrated in the figures and described below. A possible embodiment of the invention is shown by way of example in the figures. This embodiment serves to explain a possible implementation of the invention and is not to be understood as limiting. They show: Fig. 1: schematic representation of a carrier substrate with applied
[0052] waveguide layers;
[0053] Fig. 2: schematic representation of a carrier substrate with applied
[0054] Waveguide layers of Fig. 1 with a shaped high-refractive-index layer;
[0055] Fig. 3: schematic representation of a carrier substrate with applied
[0056] Waveguide layers of Fig. 1 with applied material for cladding;
[0057] Fig. 4: schematic representation of a layer waveguide with a formed upper high-refractive-index layer;
[0058] Fig. 5: schematic representation of a layer waveguide with a formed upper high-refractive-index layer and an optically nonlinear layer;
[0059] Fig. 6: schematic representation of a layer waveguide with formed upper and lower high-refractive-index layer and optically nonlinear layer;
[0060] Fig. 7: schematic representation of a clad layer waveguide with only two waveguide layers and a formed high-index layer;
[0061] Fig. 8: schematic representation of a clad layer waveguide with only two waveguide layers and formed upper high-refractive-index layer and optically nonlinear layer;
[0062] Fig. 9: schematic representation of a carrier substrate with an applied waveguide layer;
[0063] Fig. 10: schematic representation of a carrier substrate with an applied waveguide layer of Fig. 9 with a formed high-refractive-index layer; Fig. 11: schematic representation of a carrier substrate with a formed high-refractive-index layer of Fig. 10 with applied cladding material;
[0064] Fig. 12: schematic representation of a layer waveguide with applied cladding material and optically nonlinear layer on the formed high-refractive-index layer and the cladding.
[0065] Fig. 1 shows a schematic representation of a carrier substrate 1 with a refractive index n T , onto which three waveguide layers 2 are already applied. The three waveguide layers 2 consist of a lower high-index layer 4 with a refractive index n H , arranged above an optically non-linear layer 3 and arranged above another high-index layer 4 with the refractive index n H . Where n H > n T .
[0066] Fig. 2 shows the carrier substrate 1 with applied waveguide layers 2 of Fig. 1 , wherein in Fig. 2 the uppermost high-refractive-index layer 4 was formed by lateral structuring of the width to form a layer waveguide 6.
[0067] Fig. 3 shows the carrier substrate 1 with the formed uppermost high-refractive-index layer 4 of Fig. 2, wherein in Fig. 3, in a subsequent step, the formed uppermost high-refractive-index layer 4 is coated with a material 5. The material 5 for the coating has a refractive index where n H > n applies.
[0068] Figures 1, 2 and 3 show the method steps for producing the layered waveguide 6 with the provision of the carrier substrate 1 and the application of several waveguide layers in Fig. 1 as well as the formation of at least one waveguide layer in Fig. 2 and the cladding in Fig. 3. In this embodiment, the production steps are carried out one after the other.
[0069] Figures 4, 5, and 6 show various embodiments of a layered waveguide 6, each with three waveguide layers 2 on the carrier substrate 1. In Fig. 4, as in Fig. 3, only the uppermost waveguide layer 2 is formed, which is then encased laterally and on the top side. In Fig. 5, the uppermost waveguide layer 2 and the optically nonlinear layer 3 are formed, which are then encased laterally and on the top side. In Fig. 6, the upper and lower waveguide layers 2 and the optically nonlinear layer 3 arranged between them are formed, which are then encased laterally and on the top side.
[0070] Figures 7 and 8 show a further embodiment of a layered waveguide 6, each with only two waveguide layers 2 on the carrier substrate 1. In these embodiments, only one optically nonlinear layer 3 and, above it, a high-refractive-index layer 4 are formed on the carrier substrate 1. In Fig. 7, only the upper waveguide layer 2 is formed, and this is subsequently encased laterally and on the top side. In Fig. 5, the uppermost waveguide layer 2 and the optically nonlinear layer 3 are formed, and these are subsequently encased laterally and on the top side. In a modification of Figures 7 and 8, the optically nonlinear layer 3 can also be formed above the high-refractive-index layer 4.
[0071] Figures 9, 10, 11, and 12 illustrate the method for producing a layered waveguide 6, wherein application, shaping, and cladding alternate in these figures. Fig. 9 illustrates the provision of the carrier substrate 1 and the application of a first waveguide layer 2 made of a high-index layer 4. In a next step, as shown in Fig. 10, this first waveguide layer 2 is shaped by lateral structuring. In the subsequent step, as shown in Fig. 11, the first shaped waveguide layer 2 is cladding on its side surfaces. Thereafter, an optically nonlinear layer 3 is applied over the shaped first waveguide layer 2 and the cladding material 5. In a further step, this optically nonlinear layer 3 could also be shaped and / or cladding, or further waveguide layers 2 could be applied, shaped, and / or cladding.
[0072] List of reference symbols 1 Carrier substrate
[0073] 2 waveguide layers
[0074] 3 optically nonlinear layer
[0075] 4 high-index layer
[0076] 5 Cladding material 6 Layer waveguide
Claims
Claims 1 . Method for producing a layer waveguide (6) for non-linear integrated optics, comprising the steps: i) providing a carrier substrate (1) with one or more Carrier substrate layers, wherein one or the topmost carrier substrate layer has a refractive index n T ii) applying a plurality of waveguide layers (2) one above the other to the carrier substrate (1); iii) forming the layer waveguide (6) by lateral structuring of at least one waveguide layer (2); wherein the application of one or more waveguide layers (2) in ii) and the forming of at least one waveguide layer (2) in iii) takes place a) successively or b) alternately; characterized in that in step ii) at least one optically non-linear layer (3) and above and / or below at least one high-index layer (4) with a refractive index n H be applied, where nH > n T applies.
2. Method according to claim 1, characterized in that the application of the one or more waveguide layers (6) in step ii) and / or the formation of the one or more waveguide layers (6) in step iii) is determined by numerical simulations and / or analytical calculation taking into account the wavelength(s) of the mode(s) to be guided.
3. Method according to claim 1 or 2, characterized in that in step iii) at least one high-refractive-index layer (4) is formed above and below the at least one optically non-linear layer (3), or that in step iii) the at least one high-refractive-index layer (4) is formed above or below the one optically non-linear layer (3) and the at least one optically non-linear layer (3).
4. Method according to one of claims 1 to 3, characterized in that the carrier substrate (1) is provided from one or more of the following materials in step i): silicon (Si) and / or silicon dioxide (SiO2), and / or sapphire, and / or III / V or II / VI semiconductors.
5. Method according to one of claims 1 to 4, characterized in that the optically non-linear layer (3) in step ii) is applied with a thickness in the nm range or in the range of the wavelength(s) of the mode(s) to be guided.
6. Method according to one of claims 1 to 5, characterized in that the optically non-linear layer (3) is applied from one or a combination of the following materials in step ii): metal oxide, preferably tellurium dioxide (TeO2), and / or mixed oxide, preferably indium tin dioxide (In2O3:SnO2 / ITO) or aluminum zinc dioxide (Al2O3:ZnO2 / AZO), and / or nanoscale layer systems of oxides such as so-called nanolaminates, preferably zinc oxide (ZnO), titanium dioxide (TiO2) and / or silicon dioxide (SiO2), and / or ternary oxides / perovskites, preferably barium titanate (BaTOs) and / or lithium niobate (LiNbOs), and / or non-centrosymmetric crystals such as gallium phosphide (GaP), and / or beta-barium borate (BBO), and / or potassium titanyl phosphate (KTP), and / or potassium dihydrogen phosphate (KDP), and / or zinc oxide (ZnO), and / or III / V semiconductors, and / or II / VI semiconductors, and / or perovskites, and / or chalcogenide glasses, and / or 2D materials, preferably graphene, and / or transition metal dichalcogenides, preferably M0S2,MoSe2, WS2, WSe2., 7. Method according to one of claims 1 to 6, characterized in that in step ii) the optically non-linear layer (3) is applied as a layer nanolaminate.
8. Method according to one of claims 1 to 7, characterized in that the high-refractive index layer (4) with a refractive index n H made of one or more of the following materials in step ii): silicon nitride (Si3N4), titanium dioxide (TiO2), amorphous silicon (aSi), hafnium oxide (HfO2), tantalum oxide (Ta2Os) and / or silicon (Si).
9. Method according to one of claims 1 to 8, characterized in that after step iii) the following step iv) is carried out: iv) cladding the layer waveguide (6) with a material (5) with refractive index n v , where n H > n v applies.
10. Layer waveguide (6) for non-linear integrated optics, comprising: a carrier substrate (1) with one or more carrier substrate layers, wherein the one or the uppermost carrier substrate layer has a refractive index n T and at least two waveguide layers (2) arranged on the carrier substrate (1), wherein the layer waveguide (6) is formed by at least one of the waveguide layers (2), characterized in that the waveguide layers (2) have at least one optically non-linear layer (3) and above and / or below at least one high-refractive index layer (4) with a refractive index n H where n H > n T applies.
11. Layer waveguide (6) according to claim 10, characterized in that the thickness and / or the width of the waveguide layers (2) is adapted to mode properties with the wavelength of the mode to be guided, in that the mode properties with the highest light intensity are combined in the optically non-linear layer (3) located in the layer waveguide.
12. Layer waveguide (6) according to one of claims 10 or 11, characterized in that at least one high-refractive-index layer (4) above and below the at least one optically non-linear layer (3) is formed as a layer waveguide (6), or that the at least one high-refractive index layer (4) and the at least one optically non-linear layer (3) are designed as layer waveguides (6).
13. Layer waveguide (6) according to one of claims 10 to 12, characterized in that the carrier substrate (1) is formed from one or more of the following materials: silicon (Si), and / or silicon dioxide (SiO2), and / or sapphire, and / or III / V or II / VI semiconductors.
14. Layer waveguide according to one of claims 10 to 13, characterized in that the optically non-linear layer (3) has a thickness in the nm range or in the range of the wavelength(s) of the mode(s) to be guided.
15. Layer waveguide (6) according to one of claims 10 to 14, characterized in that the optically non-linear layer (3) is formed as a crystalline or amorphous layer.
16. Layer waveguide (6) according to one of claims 10 to 15, characterized in that the optically non-linear layer (3) is formed from one or a combination of the following materials: Metal oxide, preferably tellurium dioxide (TeO2), and / or mixed oxide, preferably indium tin dioxide (In2O3:SnO2 / ITO) or aluminum zinc dioxide (Al2O3:ZnO2 / AZO), and / or nanoscale layer systems of oxides such as so-called nanolaminates, preferably zinc oxide (ZnO), titanium dioxide (TiO2) and / or silicon dioxide (SiO2), and / or ternary oxides / perovskites, preferably barium titanate (BaTOs) and / or Lithium niobate (LiNbOs), and / or non-centrosymmetric crystals such as gallium phosphide (GaP), and / or beta-barium borate (BBO), and / or potassium titanyl phosphate (KTP), and / or potassium dihydrogen phosphate (KDP), and / or zinc oxide (ZnO), and / or III / V semiconductors, and / or II / VI semiconductors, and / or perovskites, and / or chalcogenide glasses, and / or 2D materials, preferably graphene, and / or transition metal dichalcogenides, preferably M0S2, MoSe2, WS2, WSe2.
17. Layer waveguide (6) according to one of claims 10 to 16, characterized in that the optically non-linear layer (3) is formed as a layer nanolaminate.
18. Layer waveguide (6) according to one of claims 10 to 17, characterized in that the high-index layer (4) with a refractive index n H made of one or more of the following materials: silicon nitride (Si3N4), titanium dioxide (TiO2), amorphous silicon (aSi), hafnium oxide (HfO2), tantalum oxide (Ta2O5) and / or silicon (Si).
19. Layer waveguide (6) according to one of claims 10 to 18, characterized in that the layer waveguide (6) is made of a material (5) with refractive index n v , where n H > n v is covered.