Photonic integrated circuit with integrated micro LED

Abstract

The present invention relates to a photonic integrated circuit comprising: an elongate waveguide having a light in-coupling surface; and an optoelectronic component arranged adjacent to or integrated into the waveguide and optically coupled to the waveguide. An optoelectronic component includes a semiconductor layer stack of a first layer of a first conductivity type, a second layer of a second conductivity type, and an active region between the first layer and the second layer, where the first layer forms a bottom surface of the semiconductor layer stack and the second layer forms a top surface of the semiconductor layer stack, and where the second layer forms a top surface of the semiconductor layer stack. A side surface of the semiconductor layer stack connects the top surface and the bottom surface. The photonic integrated circuit further includes a reflective bottom contact element covering the bottom surface and a reflective top contact element covering at least a portion of the top surface. Thus, the light in-coupling surface is adjacent to the at least first side surface of the semiconductor layer stack, and the optoelectronic component is configured to emit light through the at least first side surface of the semiconductor layer stack into the waveguide.

Description

[0001] This application claims priority to German patent application DE 10 2023 113 827.8, filed on May 25, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a photonic integrated circuit having integrated optoelectronic components such as micro-LEDs (µ-LEDs) and a method for manufacturing such a photonic integrated circuit. Background Technology

[0003] The use of light from LEDs in photonic integrated circuit (PIC) structures is desirable due to the significantly lower cost compared to lasers. However, the coupling efficiency of LEDs in PIC structures is currently very low because LEDs emit no directional radiation but have a wide beam angle distribution, even approaching that of a Lambertian beam. Furthermore, the broader spectrum of LED light compared to lasers creates coupling problems, as typical coupling grating structures are wavelength-sensitive. This, combined with the overall difficulty in designing coupling structures that can receive incident light with a wide range of incident angles and guide it into a single waveguide, leads to the current use of expensive lasers as the light source for PICs.

[0004] The purpose of this application is to overcome at least some of the aforementioned problems and to provide an improved photonic integrated circuit and a method for manufacturing the improved photonic integrated circuit. Summary of the Invention

[0005] This and other objectives are addressed through the subject matter of the independent claims. Features and additional aspects of the proposed principles are outlined in the dependent claims.

[0006] This invention enables the efficient use of LED-based light sources in conjunction with PIC (Polymer Array of Integrated Circuits) structures. It addresses the low coupling efficiency of LED light to the PIC structure by directly integrating side-emitting, optionally asymmetrically shaped microLEDs into the PIC. Therefore, the microLEDs are primarily emitted directly in-plane into the PIC waveguide environment in a guided mode manner. The microLEDs are designed to emit light only from specific surfaces, while other surfaces are coated with reflectors. The shape of the microLEDs themselves can be asymmetrical (e.g., triangular or parabolic), resulting in a collimation effect within the microLEDs themselves, leading to a narrower angular distribution of light emanating from the microLEDs within the waveguide plane. In principle, side-emitting microLEDs can be directly connected to a ridge waveguide bus. However, these microLEDs can also be first emitted into a planar waveguide environment with an adiabatic transition zone to further improve coupling efficiency.

[0007] The main advantages of such photonic integrated circuits can be, for example:

[0008] - LED light is efficiently coupled into the ridge waveguide;

[0009] - Low-cost light sources (micro LEDs) can be used;

[0010] - Avoid using complex insertion grating nanostructures;

[0011] - Back-reflected light from the side surface of the micro-LED is redirected inside the micro-LED via its asymmetrically arranged reflective surfaces, which causes more directional outgoing light and thus achieves higher coupling efficiency with the PIC structure.

[0012] - This technology can be combined with CMOS technology to enable direct contact between micro-LEDs and electronic components;

[0013] - The design of the metal reflector allows for the direct use of the metal reflector as an electrical contact;

[0014] - A similar design can be used as a detector that has all the advantages mentioned above.

[0015] According to a first aspect, a photonic integrated circuit is provided. The photonic integrated circuit includes an elongated waveguide having an optical insertion surface, and optoelectronic components disposed adjacent to or integrated into the waveguide. The optoelectronic components are optically coupled to the waveguide and include a first layer of a first conductivity type, a second layer of a second conductivity type, and a semiconductor layer stack in an active region between the first and second layers. The first layer forms a bottom surface of the semiconductor layer stack relative to the active region, and the second layer forms a top surface of the semiconductor layer stack relative to the active region. Furthermore, side surfaces of the semiconductor layer stack connect the top and bottom surfaces.

[0016] The photonic integrated circuit also includes a reflective bottom contact element covering the bottom surface and a reflective top contact element covering at least a portion of the top surface. Thus, the optoelectronic component is arranged such that the light-introducing surface is adjacent to at least a first side surface of the semiconductor layer stack, and the optoelectronic component is configured to emit light through at least the first side surface of the semiconductor layer stack into the waveguide.

[0017] By associating or integrating optoelectronic components with or into the waveguide, the low coupling efficiency in LED-to-PIC structures can be addressed, provided that the optoelectronic components emit light into the waveguide at least through their side surfaces. Therefore, the optoelectronic components are designed to emit light only from specific surfaces, while other surfaces are coated with reflectors, allowing the optoelectronic components to emit light directly into the waveguide primarily in a guided mode.

[0018] In some aspects, the active region extends substantially parallel to the main extension direction of the elongated waveguide. The optoelectronic component can be specifically arranged relative to the waveguide such that the main extension direction of the elongated waveguide forms an angle between 60° and 120° with the first side surface, or is substantially perpendicular to the first side surface. Simultaneously, the active region can extend substantially parallel to the top and / or bottom surfaces. Accordingly, it can be ensured that light generated within the active region by the optoelectronic component is emitted into the waveguide at least through its side surfaces.

[0019] In some cases, the reflective top contact element completely covers the top surface. Accordingly, light generated in the active region can be emitted only through the side surfaces (multiple) of the semiconductor layer stack. However, in cases where the reflective top contact element only covers a portion of the top surface, light generated in the active region can also be emitted through the uncovered portion of the top surface.

[0020] In some aspects, the reflective top contact element covers not only at least a portion of the top surface but also a second side surface of the semiconductor layer stack opposite the first side surface. Accordingly, light generated in the active region can be emitted only through the other side surfaces(s) of the semiconductor layer stack, and in particular can be guided to the main extension direction of the elongated waveguide. However, it is also conceivable that the second side surface is coated with a separate reflective coating not included by the top contact element.

[0021] In some aspects, the reflective top contact element covers all side surfaces of the semiconductor layer stack except for the first side surface. Accordingly, light generated in the active region can be emitted only through the first side surface of the semiconductor layer stack, and in particular, can be guided to the main extension direction of the elongated waveguide. However, it is also conceivable that the surfaces other than the first side surface are coated with a separate reflective coating not included by the top contact element.

[0022] In cases where the optoelectronic component comprises only one side surface, such as in the case of a cylindrical semiconductor layer stack, it is conceivable that the first side surface formed by the housing surface of the semiconductor layer stack can be locally coated by means of a reflective top contact element or a separate reflective coating not included by the top contact element. For example, only the front region of the housing surface can be coated by means of a reflective top contact element or a separate reflective coating not included by the top contact element. Accordingly, light generated in the active region can be emitted only through the front side region of the semiconductor layer stack, and in particular, can be guided to the main extension direction of the elongated waveguide. In some aspects, the light-introducing surface is adjacent to all the side surfaces of the semiconductor layer stack that are not covered by a reflective coating / structure and / or the portions of the top surface that are not covered by a reflective coating / structure. Therefore, the light-introducing surface can not only be a single planar surface, but also a surface structure of multiple "separate" surfaces. Furthermore, the optoelectronic component can then be configured to emit light through all these surfaces(multiple) of the semiconductor layer stack into the waveguide via the light-introducing surface.

[0023] In some aspects, a dielectric material layer is disposed between the reflective top contact element and the side surfaces (multiple) of the semiconductor layer stack. In this way, short circuits that may be caused by the reflective top contact element inside the optoelectronic component can be prevented when the reflective top contact element is in electrical contact with the bottom contact element, or when the reflective top contact element is electrically connected to the first and second layers or to both the top and bottom contact elements.

[0024] In some aspects, an optical coupling element is arranged between the optoelectronic component and the optical coupling surface. The optical coupling element can be, for example, a basic transparent adhesive that holds the optoelectronic component to the optical coupling surface, and can particularly be a refractive index matching material to improve the coupling efficiency between the optoelectronic component and the waveguide. The refractive index matching material can be, for example, a substance such as a liquid, binder (adhesive), or gel, having a refractive index very close to that of the waveguide. When two substances with the same refractive index come into contact, light propagates from one direction to the other without reflection or refraction.

[0025] In some aspects, optoelectronic components are disposed within a waveguide or a cavity of waveguide material. The waveguide may be located, particularly at one end of its ends or at another point along its main extension direction, and the cavity extends from the upper surface of the waveguide at least into the waveguide medium. The optoelectronic components may be disposed, particularly within the cavity of the waveguide, such that the optoelectronic components emit light into the waveguide through at least a first side surface of a stack of semiconductor layers. The optical insertion surface may be formed, particularly, by one, several, or all of the boundary surfaces of the cavity.

[0026] In some aspects, the cavity is filled with an encapsulation material, particularly a reflective encapsulation material for encapsulating optoelectronic components disposed within the cavity. Specifically, the encapsulation material can act as a reflective coating on the portions of the side surfaces(multiple) and / or top surfaces of the semiconductor layer stack that are not covered by reflective top contact elements. The encapsulation material can cover all side surfaces except the first side surface, can cover only the side surfaces adjacent to the first side surface without covering the first side surface and the opposing second side surface, and / or the encapsulation material can cover the top surface not covered by reflective top contact elements to prevent undesirable light emission through the respective side surfaces(multiple) and / or top surface.

[0027] In some aspects, a waveguide includes: an optical core serving as an optical guiding medium, comprising a high refractive index material such as, for example, SiN; and an optical cladding surrounding the optical core in the circumferential direction, the optical cladding comprising a low refractive index material such as, for example, SiO2.

[0028] In some aspects, the light-introducing surface is adjacent to a second side surface of the semiconductor layer stack opposite to the first side surface. In this case, the optoelectronic component is configured to also emit light through the second side surface into the waveguide. This is particularly applicable if light is to be guided in two different directions starting from the central optoelectronic component. Specifically, the waveguide may include a cavity in the middle along its main extension direction, and the optoelectronic component may be configured to emit light into two adjacent waveguide portions. However, it is also conceivable that a second waveguide is arranged adjacent to the second side surface of the semiconductor layer stack, and the optoelectronic component is configured to emit light through the second side surface into the second waveguide. Therefore, a cavity is not required inside the waveguide. However, it should be understood that the emission of light in two different directions and therefore two different waveguides / waveguide portions by means of the optoelectronic component is merely exemplary, and the emission of light in three, four, five... directions and therefore three, four, five... different waveguides / waveguide portions by means of the optoelectronic component is also possible. In such a case, optoelectronic components can, for example, be arranged at the center and configured to emit light through their respective star-shaped side surfaces into corresponding different waveguides / waveguide sections.

[0029] In some aspects, the optical input surface is adjacent to at least a portion of the top surface, and the optoelectronic component is configured to emit light through at least a portion of the top surface into the waveguide. In this case, at least a portion of the top surface is not covered by a reflective top contact element or a reflective coating, and the optoelectronic component is directly integrated into the waveguide. Light emitted through at least a portion of the top surface enters the waveguide and is directly guided into the waveguide along the main extension direction due to internal reflections within the waveguide.

[0030] In some aspects, when viewed in top and / or side views, the semiconductor layer stack of the optoelectronic component includes an increased cross-section in the direction of the waveguide. The semiconductor layer stack can be formed, for example, in a conical, wedge-shaped, or ellipsoidal shape. In particular, the semiconductor layer stack / optoelectronic component can be formed asymmetrically to provide a structure in which the light guide within the semiconductor layer stack / optoelectronic component is enhanced when reflective material / contact elements are coated on its respective outer surfaces (side surfaces (multiple), bottom surfaces (multiple), and top surfaces (multiple)). The semiconductor layer stack / optoelectronic component can, for example, form a reflector-like structure together with reflective contact elements and / or reflective coatings, which is configured to transmit light into the waveguide at least through the first side surface in an improved manner.

[0031] In some aspects, photonic integrated circuits also include a carrier substrate on which waveguides and optoelectronic components are disposed, particularly the integrated circuit itself. The carrier substrate specifically includes an upper surface on which waveguides and optoelectronic components are disposed, with the waveguides extending therefrom.

[0032] In some aspects, the optoelectronic component is a microLED. A microLED can be, in particular, an element having a side length of less than 100 micrometers, less than 500 micrometers, less than 20 micrometers, less than 10 micrometers, or less than 5 micrometers, configured to emit light of a desired wavelength. However, the optoelectronic component can also be a microdetector (µ-detector). A microdetector can be, in particular, an element having a side length of less than 100 micrometers, less than 500 micrometers, less than 20 micrometers, less than 10 micrometers, or less than 5 micrometers, configured to detect light of a desired wavelength. In some aspects, however, the optoelectronic component can also be an LED or microLED or detector or microdetector having a side length greater than 500 micrometers, configured to emit / detect light of a desired wavelength.

[0033] In some respects, the active region includes a quantum well or multiple quantum well structure. However, the active region may also include quantum dots or any other structure used to enhance light generation within the active region.

[0034] In some aspects, photonic integrated circuits also include multiple optoelectronic components optically coupled to the same waveguide. For example, red, green, and blue emitting LEDs can be optically coupled to one and the same waveguide to provide, for example, white light or any other desired color of light at the out-coupled surface of the waveguide by mixing the light. The optoelectronic components can be arranged, configured, and designed as described above.

[0035] In some aspects, the waveguide includes an optical combining element arranged adjacent to a plurality of optoelectronic components. This optical combining element can act as an adiabatic transition region formed by the waveguide or the waveguide material itself. An optical insertion surface adjacent to at least a first side surface of the optoelectronic components can be at least partially formed by the optical combining element.

[0036] In some aspects, the waveguide includes an outgoing coupling surface configured to be coupled to another waveguide. In particular, the photonic integrated circuit of this application may be a separate module comprising a waveguide / waveguide portion having integrated optoelectronic components according to some of the foregoing aspects, which can be integrated into a larger and more complex photonic integrated circuit.

[0037] In this application, optoelectronic components primarily refer to transmitters configured to emit light into waveguides (multiple). However, it should be understood that the foregoing embodiments and aspects can also be modified and used to indicate that the optoelectronic components are detectors configured to detect light guided from waveguides (multiple) to a detector.

[0038] In some aspects, a method for manufacturing a photonic integrated circuit according to some of the foregoing aspects is provided. The method includes the following steps:

[0039] For example, a slender waveguide can be grown on a substrate using plasma-enhanced chemical vapor deposition (PECVD) technology;

[0040] For example, cavities can be etched into waveguides using plasma etching.

[0041] For example, optoelectronic components can be arranged in the cavity using micro-transfer printing;

[0042] Optoelectronic components are electrically contacted via top and bottom contact elements using processes such as sputtering and / or photolithography; and

[0043] Optoelectronic components are encapsulated in cavities using processes such as PECVD.

[0044] In some aspects, another method for manufacturing photonic integrated circuits according to some of the foregoing aspects is provided. This method includes the following steps:

[0045] Optoelectronic components are arranged on a carrier substrate;

[0046] The optoelectronic components are electrically contacted by means of top and bottom contact elements; and

[0047] Slender waveguides are grown on a substrate to encapsulate optoelectronic components. Attached Figure Description

[0048] Further aspects and implementations based on the proposed principles will become apparent from the various embodiments and examples described in detail with reference to the accompanying drawings, wherein,

[0049] Figure 1 A photonic integrated circuit based on some aspects of the proposed principles is shown;

[0050] Figure 2Another implementation of a photonic integrated circuit based on some aspects of the proposed principles is shown;

[0051] Figure 3 and Figure 4 A side view of another implementation of a photonic integrated circuit based on some aspects of the proposed principles is shown;

[0052] Figure 5 and Figure 6 A top view shows another implementation of a photonic integrated circuit based on some aspects of the proposed principles;

[0053] Figure 7 and Figure 8 A side view and a top view of another embodiment of a photonic integrated circuit based on some aspects of the proposed principles are shown;

[0054] Figure 9 Another implementation of a photonic integrated circuit based on some aspects of the proposed principles is shown. Detailed Implementation

[0055] The following embodiments and examples disclose various aspects and combinations thereof based on the proposed principles. The embodiments and examples are not always to scale. Similarly, different elements may be shown enlarged or reduced in size to emphasize aspects. It goes without saying that the various aspects, embodiments, and examples shown in the figures can be combined with each other without contradiction to the principles of the invention. Some aspects illustrate regular structures or forms. It should be noted that in practice, minor differences and deviations from the ideal form may occur; however, these will not contradict the concept of the invention.

[0056] Furthermore, the various figures and aspects are not necessarily shown at the correct dimensions, and the proportions between the elements are not necessarily substantially correct. Some aspects are highlighted by showing them enlarged. However, terms such as "above," "over," "below," "under," "larger," and "smaller" are correctly used to represent the elements in the figures. Therefore, such relationships between elements can be inferred from the figures.

[0057] Figure 1A top view of a first embodiment of a photonic integrated circuit 1 based on some aspects of the proposed principles is shown. The photonic integrated circuit 1 includes an elongated waveguide 2 (e.g., a silicon nitride (SiN) ridge waveguide) and an optoelectronic component 4 integrated into the waveguide 2. The waveguide 2 can be described as elongated because it extends primarily along the main extension direction x compared to the vertical direction y. The optoelectronic component 4 is optically coupled to the waveguide 2 due to its integration into the waveguide 2, and light emitted from the optoelectronic component 4 is coupled into the waveguide 2 through a light-injection surface 3. Therefore, the light-injection surface 3 is directly adjacent to at least one front surface of the optoelectronic component 4 due to its integration. In the illustrated embodiment, the optoelectronic component 4 includes an asymmetrical shape, i.e., a wedge shape having a top surface, a bottom surface, and three side surfaces. Light is emitted into the waveguide 2 through the front surface; however, the other two side surfaces, as well as the top and bottom surfaces, may include a reflective coating (e.g., a metal film) to internally reflect light towards the direction of the front surface. The asymmetric shape in the xy plane, combined with the reflective coating, helps to collimate the generated light L, ensuring that most of the optical power is directed into waveguide 2. The optoelectronic component 4 is specifically a microLED having a first layer of a first conductivity type, a second layer of a second conductivity type, and an active region between the first and second layers. The microLED is, for example, a very small LED with a side length of less than 20 micrometers.

[0058] Figure 2 A side view of another embodiment of a photonic integrated circuit 1 based on some aspects of the proposed principles is shown. The photonic integrated circuit 1 includes an elongated waveguide 2 and an optoelectronic component 4 integrated into the waveguide 2. The optoelectronic component 4 is a miniature LED and includes a first layer 6 of a first conductivity type, a second layer 8 of a second conductivity type, and a semiconductor layer stack 5 of an active region 7 between the first and second layers. The semiconductor layer stack 5 is defined by a top surface 10, a bottom surface 9, and a side surface 11 connecting the top surface 10 and the bottom surface 9, forming a mesa structure in the illustrated embodiment. Therefore, the side surface 11 is inclined relative to the bottom surface 9 / top surface 10.

[0059] Waveguide 2 can be grown around optoelectronic component 4, meaning that optoelectronic component 4 is arranged in an ideal cavity 16 surrounding optoelectronic component 4 from all sides except one side. A reflective bottom contact element 12 covering bottom surface 9 is arranged on bottom surface 9. A reflective top contact element 13 covering only a portion of top surface 10 is arranged on top surface. The reflective top contact element 13 also extends from top surface 10 along second side surface 11b, thereby completely covering second surface 11b. To prevent short circuits inside optoelectronic component 4, dielectric material layer 14 is arranged at least in the region of first layer 6 and active region 7 between semiconductor layer stack 5 and top contact element 13.

[0060] The optoelectronic component 4 is configured to emit light L through a first side surface 11a opposite to the second side surface 11b and through a top surface 10 not covered by the top contact element 13. The surfaces of the cavity 16 adjacent to the first side surface 11a and the top surface 10 form the light-introduction coupling surface 3 of the waveguide 2, through which the light L emitted from the optoelectronic component 4 is coupled into the waveguide 2. Due to the reflective bottom contact element 12 and the reflective top contact element 13 extending at least along the second side surface 11b, the coupling of light L into the waveguide 2 occurs primarily in a directional manner.

[0061] Figure 3 and Figure 4 Each of the following shows a side view of another embodiment of the photonic integrated circuit 1 based on some aspects of the proposed principles. The photonic integrated circuit 1 includes an elongated waveguide 2 and an optoelectronic component 4 integrated into the waveguide 2. The optoelectronic component 4 is a miniature LED and includes a first layer 6 of a first conductivity type, a second layer 8 of a second conductivity type, and a semiconductor layer stack 5 of an active region 7 between the first and second layers. The semiconductor layer stack 5 is defined by a top surface 10, a bottom surface 9, and a side surface 11 connecting the top surface 10 and the bottom surface 9.

[0062] Waveguide 2 can be grown, for example, around optoelectronic component 4, but optoelectronic component 4 can also be disposed at the end of waveguide 2, with light coupled to the end surface of the waveguide, thereby forming optical coupling surface 3. Optoelectronic component 4 can also be "semi-embedded" in waveguide 2, such that only two opposing side surfaces of the semiconductor layer stack 5 face waveguide 2. This can be achieved, for example, by creating cavities in waveguide 2 at any location along its main extension direction x, wherein the cavities extend through the entire thickness of the waveguide, thereby dividing the waveguide into independent sections. Optoelectronic component 4 can then be disposed between the cavities of the waveguide.

[0063] A reflective bottom contact element 12 covering the bottom surface 9 is arranged on the bottom surface 9, and a reflective top contact element 13 covering the top surface 10 is arranged on the top surface. The second side surface 11b of the semiconductor layer stack 5 is also covered by a reflective coating 22. To prevent short circuits inside the optoelectronic component 4, a dielectric material layer 14 is arranged between the semiconductor layer stack 5 and the reflective coating 22.

[0064] The optoelectronic component 4 is configured to emit light L through a first side surface 11a opposite to the second side surface 11b. The light coupling surface 3 of the waveguide 2, through which the light L emitted from the optoelectronic component 4 is coupled to the waveguide 2, is arranged directly adjacent to the first side surface 11a. Due to the reflective bottom contact element 12 and the reflective top contact element 13, as well as the reflective coating on the second side surface 11b, the coupling of light L to the waveguide 2 occurs primarily in a directional manner, as shown in the figure.

[0065] and Figure 3 In contrast, when viewed in the side view / xz plane, Figure 4 The semiconductor layer stack 5 includes an increased cross-section in the direction of waveguide 2. Specifically, the semiconductor layer stack 5 is in the form of a semi-ellipsoid, wherein the first side surface 11a acts as the open end of the ellipsoid through which light L is emitted from the optoelectronic component 4 into the waveguide. Therefore, the top and bottom surfaces are bent to act as reflector structures, which helps to collimate the generated light L, thereby ensuring that most of the optical power is guided into waveguide 2.

[0066] Figure 5 and Figure 6 Each of the following diagrams shows a top view of another embodiment of the photonic integrated circuit 1 based on some aspects of the proposed principles. The photonic integrated circuit 1 includes an elongated waveguide 2 and an optoelectronic component 4 integrated into the waveguide 2, both disposed on a carrier substrate 21. The optoelectronic component 4 is disposed in a cavity 16 at one end of the carrier substrate 21 at one end of the waveguide 2. The optoelectronic component 4 is fixed to an optical coupling surface 3 of the waveguide by means of an optical coupling element 15, using its first side surface 11a, such that the optical coupling element 15 is disposed between the optoelectronic component 4 and the optical coupling surface 3. The optical coupling element 15 may be, for example, a substantially transparent adhesive for fixing the optoelectronic component 4 to the optical coupling surface 3, and may particularly be a refractive index matching material to improve the coupling efficiency between the optoelectronic component 4 and the waveguide 2.

[0067] like Figure 6 As shown, cavity 16 can also be filled with encapsulation material 17, which in this case is a reflective encapsulation material (e.g., silicon and TiO2), to surround optoelectronic component 4 on all side surfaces except the first side surface 11a. Accordingly, in combination with, for example, reflective top contact elements and reflective bottom contact elements, the out-coupling efficiency of light from optoelectronic component 4 to waveguide 2 can be improved.

[0068] Figure 7 and Figure 8 Side and top views of another embodiment of a photonic integrated circuit 1 based on some aspects of the proposed principles are shown. The photonic integrated circuit 1 includes an elongated waveguide 2 and optoelectronic components 4 integrated into the waveguide 2, both disposed on a carrier substrate 21. The optoelectronic components 4 are disposed in a cavity 16 formed in the waveguide 2. The waveguide 2 includes: a photoconductive core 18 as a photoconductive medium, comprising a high-refractive-index material such as, for example, SiN; and a photoconductive cladding 19 surrounding the photoconductive core 18 in a circumferential direction, the photoconductive cladding 18 comprising a low-refractive-index material such as, for example, SiO2. In the illustrated embodiment, the carrier substrate 21 is in the form of an integrated circuit for powering / operating the optoelectronic components 4.

[0069] Since the optoelectronic component 4 is integrated into the waveguide 2, it is optically coupled to the waveguide 2, and the light emitted from the optoelectronic component 4 is coupled into the waveguide 2 through the light-injection surface 3 of the waveguide 2. Therefore, the light-injection surface 3 is adjacent to the first side surface 11a and the opposing second side surface 11b of the optoelectronic component 4 due to its integration. Light is emitted into the waveguide 2 through the first side surface 11a and the second side surface 11b, and the top and bottom surfaces, and optionally the other two side surfaces, also include reflective coatings (e.g., metal films forming the top and bottom contact elements) to cause the light to be internally reflected towards the first and second side surfaces.

[0070] Due to the integration of the optoelectronic element 4 within the waveguide at a location (e.g., in the middle) along the main extension direction of the waveguide, and due to the cavity 16 within the waveguide 2, the waveguide 2 is divided into two parts. The first part 2a of the waveguide extends from the first side surface 11a of the semiconductor layer stack 5 in the main extension direction x, while the second part 2b of the waveguide extends from the second side surface 11b of the semiconductor layer stack 5 in the opposite direction.

[0071] Optical coupling elements 15 are respectively arranged between the first side surface 11a and the optical coupling surface 3 of the first part 2a of the waveguide, and between the second side surface 11b and the optical coupling surface 3 of the second part 2b of the waveguide. With the aid of the optical coupling elements 15, light generated inside the optoelectronic component 4 is coupled into the waveguide 2 via the first side surface, the second side surface, and the optical coupling surface 3.

[0072] Cavity 16 is also encapsulated by means of an encapsulation material 17 surrounding the optoelectronic component 4 on all side surfaces except the first side surface 11a and the second side surface 11b. The encapsulation material 17 also surrounds the top contact element 13 and the bottom contact element 12 respectively disposed on the top surface 10 and the bottom surface 9. The top contact element 13 and the bottom contact element 12 are each configured to reflect light generated in the optoelectronic component 4 and each completely covers the top surface 10 and the bottom surface 9.

[0073] The photonic integrated circuit also includes a first contact hole 23 and a second contact hole 24, thereby electrically connecting the top contact element and the bottom contact element to the carrier substrate 21. The first contact hole extends from the top contact element 13 through the encapsulation material 17 into the carrier substrate, while the second contact hole 24 extends through a portion of the carrier substrate 21 to the bottom contact element 12.

[0074] like Figure 8 As shown, waveguide 2 may include a light combining section arranged adjacent to optoelectronic component 4. Accordingly, optoelectronic component 4 may be a larger microLED, and it is still possible for optoelectronic component 4 to couple the light from the larger microLED into a narrower waveguide 2.

[0075] Figure 9 Another embodiment of the photonic integrated circuit 1 based on some aspects of the proposed principles is shown. Here, multiple optoelectronic components 4a, 4b, 4c are integrated into the photonic integrated circuit 1 and optically coupled to a single waveguide 2. Thus, the optoelectronic components 4a, 4b, 4c can, for example, be configured to emit light of different wavelengths. Subsequently, the light is coupled to the light-injection surface 3 of the waveguide, wherein the waveguide comprises a wide waveguide environment before being focused into the ridge waveguide. The wide waveguide environment thus acts as an optical combining element 20 arranged adjacent to the multiple optoelectronic components 4a, 4b, 4c.

[0076] List of reference numerals

[0077] 1 Photonic Integrated Circuit

[0078] Waveguides 2, 2a, 2b

[0079] 3 Optical insertion surface

[0080] 4 optoelectronic components

[0081] 5, 5a, 5b, 5c semiconductor layers stacked

[0082] 6 First layer

[0083] 7 active areas

[0084] 8 Second layer

[0085] 9 Bottom surface

[0086] 10 Top Surface

[0087] 11, 11a, 11b side surfaces

[0088] 12 Bottom Contact Components

[0089] 13 Top Contact Element

[0090] 14 dielectric material layers

[0091] 15 Optical Input Couplers

[0092] 16 chambers

[0093] 17 Packaging Materials

[0094] 18 optical fiber cores

[0095] 19 Optical cladding

[0096] 20 optical combination elements

[0097] 21 carrier substrate

[0098] 22 Reflective Coating

[0099] Contact holes 23 and 24

[0100] x Main extension direction

[0101] L-light

Claims

1. Photonic integrated circuit (1) comprising: an elongated waveguide (2) having a light in-coupling surface (3); an optoelectronic component (4) arranged adjacent to or integrated into the waveguide (2) and optically coupled to the waveguide (2), the optoelectronic component (4) comprising a semiconductor layer stack (5) having: a first layer (6) of a first conductivity type; a second layer (8) of a second conductivity type; and an active region (7) between the first layer (6) and the second layer (8); wherein the first layer (6) forms a bottom surface (9) of the semiconductor layer stack (5) and the second layer (8) forms a top surface (10) of the semiconductor layer stack (5); and wherein side surfaces (11) of the semiconductor layer stack (5) connect the top surface (10) and the bottom surface (9); a reflective bottom contact element (12) covering the bottom surface (9); and a reflective top contact element (13) covering at least part of the top surface (10); wherein the light in-coupling surface (3) is adjacent to at least a first side surface (11a) of the semiconductor layer stack (5); wherein the optoelectronic component (4) is configured to emit light into the waveguide (2) through at least the first side surface (11a) of the semiconductor layer stack (5); and wherein the semiconductor layer stack (5) comprises a cross-section that increases in direction of the waveguide when viewed in a top view and / or a side view.

2. The photonic integrated circuit of claim 1, wherein, The active region (7) extends substantially parallel to a main extension direction (x) of the elongated waveguide (2).

3. The photonic integrated circuit of claim 1 or 2, wherein, The active region (7) extends substantially parallel to the top surface (10) and / or the bottom surface (9).

4. The photonic integrated circuit of any of claims 1 to 3, wherein, The reflective top contact element (13) covers the top surface (10) completely.

5. The photonic integrated circuit of any of claims 1 to 4, wherein, The reflective top contact element (13) covers a second side surface (11b) of the semiconductor layer stack (5) opposite the first side surface (11a).

6. The photonic integrated circuit of any of claims 1 to 5, wherein, The reflective top contact element (13) covers all side surfaces (11) of the semiconductor layer stack (5) except the first side surface (11a).

7. The photonic integrated circuit of any of claims 1 to 6, wherein, A layer (14) of dielectric material is arranged between the reflective top contact element (13) and the side surfaces (11) of the semiconductor layer stack (5).

8. The photonic integrated circuit of any of claims 1 to 7, wherein, A light in-coupling element (15) is arranged between the optoelectronic component (4) and the light in-coupling surface (3).

9. The photonic integrated circuit of any of claims 1 to 8, wherein, The optoelectronic component (4) is arranged in a cavity (16) in the waveguide (2).

10. The photonic integrated circuit of claim 9, wherein, The cavity (16) is filled with a packaging material (17), in particular a reflective packaging material.

11. The photonic integrated circuit of any of claims 1 to 10, wherein, The optoelectronic component (4) is a micro-LED.

12. The photonic integrated circuit of any of claims 1 to 11, wherein, The waveguide (2) comprises a light guide core (18) comprising SiN and a light guide cladding (19) surrounding the light guide core (18) in a circumferential direction, the light guide cladding (19) comprising SiO2.

13. The photonic integrated circuit of any of claims 1 to 12, wherein, The light-in-coupling surface (3) is adjacent to a second side surface (lib) of the semiconductor layer stack (5) opposite the first side surface (11a), and wherein the optoelectronic component (4) is configured to emit light into the waveguide (2) through the second side surface (lib).

14. The photonic integrated circuit of any of claims 1 to 13, wherein, The light-in-coupling surface (3) is adjacent to at least a portion of the top surface (10), and wherein the optoelectronic component (4) is configured to emit light into the waveguide (2) through the at least portion of the top surface (10).

15. Photonic integrated circuit according to any of claims 1 to 14, further comprising a plurality of optoelectronic components (4a, 4b, 4c) optically coupled to the same waveguide (2).

16. The photonic integrated circuit of claim 15, wherein, The waveguide (2) comprises a light-combining element (20) arranged adjacent to the plurality of optoelectronic components (4a, 4b, 4c).

17. The photonic integrated circuit of any of claims 1 to 16, wherein, The semiconductor layer stack (5) is formed conically, wedge-shaped or ellipsoidal.

18. Photonic integrated circuit according to any of claims 1 to 17, further comprising a carrier substrate (21), in particular an integrated circuit, on which the waveguide (2) and the optoelectronic component (5) are arranged.

19. A method for manufacturing a photonic integrated circuit (1) according to any of claims 1 to 18, the method comprising the steps of: growing the elongated waveguide (2) on a carrier substrate (21); etching a cavity (16) into the waveguide (2); arranging the optoelectronic component (4) in the cavity (16); electrically contacting the optoelectronic component (4) by means of the top contact element (13) and the bottom contact element (12); and encapsulating the optoelectronic component (4) in the cavity (16).

20. A method for manufacturing a photonic integrated circuit (1) according to any of claims 1 to 18, the method comprising the steps of: arranging the optoelectronic component (4) on a carrier substrate (21); electrically contacting the optoelectronic component (4) by means of the top contact element (13) and the bottom contact element (12); and growing the elongated waveguide (2) on the carrier substrate (21) to encapsulate the optoelectronic component (4).

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