OPTOELECTRONIC MODULE

Abstract

An optoelectronic module comprises a photonic chip and a light-emitting diode chip. The light-emitting diode chip comprises a first surface, a second surface opposite the first surface, and side surfaces extending between the first surface and the second surface. The photonic chip comprises a waveguide. The waveguide comprises a core arranged between a lower cladding layer and an upper cladding layer. An opening is formed in the upper cladding layer. The light-emitting diode chip is arranged on the core in the opening such that the first surface is oriented toward the core.

Description

[0001] The present invention relates to an optoelectronic module.

[0002] This patent application claims priority from German patent application 10 2023 110 417.9, the disclosure of which is hereby incorporated by reference.

[0003] It is known in the art to use lasers to couple light into a waveguide of a photonic chip.

[0004] It is an object of the present invention to provide an optoelectronic module. This object is achieved by an optoelectronic module according to the independent claim. Preferred embodiments are disclosed in the dependent claims.

[0005] An optoelectronic module comprises a photonic chip and a light-emitting diode chip. The light-emitting diode chip comprises a first surface, a second surface opposite the first surface, and side surfaces extending between the first surface and the second surface. The photonic chip comprises a waveguide. The waveguide comprises a core arranged between a lower cladding layer and an upper cladding layer. An opening is formed in the upper cladding layer. The light-emitting diode chip is arranged on the core in the opening such that the first surface is oriented toward the core.

[0006] The optoelectronic module enables the coupling of light emitted by the LED chip into the waveguide of the photonic chip. An LED chip offers the advantage over a laser chip of being smaller and more cost-effective. Arranging the LED chip directly on the core advantageously enables efficient coupling of the light emitted by the LED chip.

[0007] In one embodiment of the optoelectronic module, a reflective box is formed around the LED chip. Advantageously, the reflective box can serve to reflect light emitted by the LED chip that is not directly coupled into the core of the waveguide toward the core, allowing the reflected light to be coupled into the core. This can increase the efficiency of the optoelectronic module.

[0008] In one embodiment of the optoelectronic module, the reflective box comprises a first polymer and a second polymer with different refractive indices. The first polymer is in contact with the side surfaces of the LED chip. The second polymer is arranged around the first polymer. Advantageously, this arrangement of the first polymer and the second polymer enables the reflection of light at an interface between the first polymer and the second polymer.

[0009] In one embodiment of the optoelectronic module, a refractive index of the first polymer matches a refractive index of the core. A refractive index of the second polymer matches a refractive index of the upper cladding layer. Advantageously, this combination of refractive indices enables efficient coupling of light emitted by the LED chip into the waveguide of the photonic chip.

[0010] In one embodiment of the optoelectronic module, a metallic mirror layer is arranged between the first polymer and the second polymer. More advantageously, providing a metallic mirror layer between the first polymer and the second polymer enables particularly effective reflection of light at the boundary between the first polymer and the second polymer.

[0011] In one embodiment of the optoelectronic module, the reflective box comprises a metallic mirror layer arranged on the second surface and on the side surfaces of the LED chip. Advantageously, a metallic mirror layer arranged on the LED chip efficiently reflects light emitted by the LED chip in a direction toward the core of the waveguide, allowing this light to be coupled into the waveguide.

[0012] In one embodiment of the optoelectronic module, a metallic mirror layer is arranged between the lower cladding layer and the core beneath the LED chip. Light emitted by the LED chip that is not coupled into the core of the waveguide can be reflected back to the core by the metallic mirror layer. The reflected light can be coupled into the core of the waveguide after reflection.

[0013] In one embodiment of the optoelectronic module, the opening of the upper cladding layer is at least partially filled with a polymer. This polymer can serve to replace the missing upper cladding layer in the opening, so that light coupled into the core of the waveguide is effectively confined to the core of the waveguide.

[0014] In one embodiment of the optoelectronic module, the core has a recess. The LED chip is arranged in the recess. This arrangement can help increase the amount of light emitted by the LED chip that is coupled into the waveguide.

[0015] In one embodiment of the optoelectronic module, the core comprises a contact section that has a greater width than adjacent sections of the core. The LED chip is arranged on the contact section of the core. This advantageously allows the use of an LED chip with a width that is greater than the width of most sections of the core.

[0016] In one embodiment of the optoelectronic module, a reflective structure is arranged on a side of the upper cladding layer opposite the core, in a vicinity of the LED chip. The reflective structure can serve to reflect light reflected by the LED chip, which has not yet been coupled into the waveguide, back to the core of the waveguide, so that this light can be coupled into the core of the waveguide after reflection.

[0017] In one embodiment of the optoelectronic module, the reflective structure comprises a microstructure. A reflective structure designed as a microstructure can enable effective reflection of light.

[0018] In one embodiment of the optoelectronic module, electrical contacts of the LED chip are arranged on the second surface. This advantageously enables the LED chip to be connected in a simple manner.

[0019] In one embodiment of the optoelectronic module, the first surface of the LED chip has a rectangular shape. Long sides of the first surface are oriented parallel to a longitudinal direction of the waveguide. This advantageously allows the first surface of the LED chip to encompass a larger size even with a limited width.

[0020] In one embodiment of the optoelectronic module, the side surfaces of the LED chip are inclined at an angle other than 90° relative to the first surface. This can advantageously increase the amount of light emitted by the LED chip that can be coupled into the waveguide.

[0021] In one embodiment of the optoelectronic module, an adhesive is arranged between the core and the first surface of the LED chip. The adhesive can have a refractive index that matches the refractive indices of the LED chip and the core.

[0022] In one embodiment of the optoelectronic module, the adhesive comprises scattering particles. Scattering particles embedded in the adhesive can increase the efficiency of coupling the light emitted by the LED chip into the waveguide.

[0023] The above-described characteristics, features and advantages of the invention, as well as the manner in which they are achieved, will be more clearly and comprehensively understood in connection with the following description of embodiments, which are explained in more detail in connection with the drawings, in which, in schematic representation, Fig. 1 shows a sectional view of parts of a variant of an optoelectronic module; Fig. 2 shows a top view of the optoelectronic module; Fig. 3 shows a sectional view of parts of a variant of an optoelectronic module; Fig. 4 shows a sectional view of parts of a variant of an optoelectronic module; Fig. 5 shows a sectional view of parts of a variant of an optoelectronic module; Fig. 6 shows a sectional view of parts of a variant of an optoelectronic module; and Fig. 7 shows a sectional view of parts of a variant of an optoelectronic module.

[0024] Fig. 1 shows a schematic sectional view of a variant of an optoelectronic module 10. For the sake of simplicity, not all components of the optoelectronic module 10 are shown. Fig. 2 shows a schematic top view of the same optoelectronic module 10.

[0025] The optoelectronic module 10 comprises a photonic chip 100. The photonic chip 100 can also be referred to as a photonic integrated circuit. The photonic chip 100 comprises a waveguide 110 extending along a longitudinal direction 111. The waveguide 110 comprises a core 200 arranged between a lower cladding layer 300 and an upper cladding layer 400. The upper cladding layer 400 is Fig. 2 not visible.

[0026] The lower cladding layer 300 and the upper cladding layer 400 typically comprise a refractive index that is less than a refractive index of the core 200.

[0027] As in Fig. 1, the upper cladding layer 400 includes an opening 410 in which the upper cladding layer 400 has been removed to expose the core 200.

[0028] The optoelectronic module 10 comprises a light-emitting diode chip 500. The light-emitting diode chip 500 has a first surface 501, a second surface 502 opposite the first surface 501, and four side surfaces 503 extending between the first surface 501 and the second surface 502.

[0029] In the Fig. 1 and Fig. In the example shown in Figure 2, the LED chip 500 comprises only epitaxial layers. A growth substrate has been removed. However, in other variants, the LED chip 500 may comprise a growth substrate or another carrier substrate.

[0030] The light-emitting diode chip 500 is designed to emit light 530, for example, visible light. The light 530 is emitted from the first surface 501 and the side surfaces 503. A mirror layer can be arranged on the second surface 502 so that no light is emitted from the second surface 502 of the light-emitting diode chip 500. Internally, the light 530 is generated in an active layer 520 of the light-emitting diode chip 500.

[0031] The LED chip 500 comprises a plurality of electrical contacts 510 for supplying the LED chip 500 with an electrical voltage and an electrical current. Fig. 1 and Fig. In the example shown in Figure 2, the electrical contacts 510 are arranged on the second surface 502 of the light-emitting diode chip 500.

[0032] The LED chip 500 is arranged on the core 200 of the waveguide 110 in the opening 410 formed in the upper cladding layer 400. The first surface 501 of the LED chip 500 is oriented toward the core 200. This arrangement serves to couple at least portions of the light 530 emitted by the LED chip 500 into the core 200 of the waveguide 110.

[0033] The LED chip 500 is attached to the core 200 using an adhesive 700. The adhesive 700 is disposed between the core 200 and the first surface 501 of the LED chip 500. The adhesive 700 may also cover the remaining surface of the core 200 exposed in the opening 410 of the upper cladding layer 400 and may also extend onto the upper cladding layer 400. Conveniently, a refractive index of the adhesive 700 is adapted to the refractive indices of the LED chip 500 and the core 200. For example, the adhesive 700 may have a refractive index with a value between those of the LED chip 500 and the core 200.

[0034] In some variants of the optoelectronic module 10, the adhesive 700 can be replaced with a different attachment material. In one example, porous GaN is used to attach the LED chip 500 to the core 200.

[0035] The adhesive 700 may include embedded scattering particles 710. Scattering particles 710 may be provided to scatter light 530 emitted by the light-emitting diode chip 500 to change an angular distribution of the light 530. This may increase the amount of light 530 successfully coupled into the core 200 of the waveguide 110. However, the scattering particles 710 may be omitted.

[0036] The first surface 501 of the LED chip 500 may include a roughening, for example, a roughening on a micrometer scale. The roughening may assist the coupling of light 530 out of the LED chip 500 at the first surface 501. Alternatively or additionally, the surface of the core 200 exposed in the opening 410 may include a roughening, for example, a roughening on a micrometer scale. Roughening the surface of the core 200 may assist the coupling of light 530 into the core 200.

[0037] Fig. 2 shows that the core 200 includes a contact section 210. A width 215 of the core 200, measured in a direction perpendicular to the longitudinal direction 111 of the waveguide 110, is greater in the contact section 210 than in adjacent sections of the core 200. At least a portion of the contact section 210 is exposed in the opening 410 of the upper cladding layer 400. The light-emitting diode chip 500 is arranged on the contact section 210 of the core 200. The contact section 210, which has a greater width 215, allows the first surface 501 of the light-emitting diode chip 500 to include a width that is greater than the width 215 of the core 200 in sections outside the contact section 210. If the greater width 215 of the contact portion 210 is not required, the contact portion 210 may comprise the same width 215 as the other portions of the core 200.

[0038] In the Fig. 1 and Fig. In the example illustrated in Figure 2, the first surface 501 of the light-emitting diode chip 500 has a rectangular shape. Longitudinal sides 504 of the first surface 501 are oriented parallel to the longitudinal direction 111 of the waveguide 110. In this way, the shape of the light-emitting diode chip 500 and its first surface 501 is optimized for placement on the long and narrow surface of the core 200. The first surface 501 of the light-emitting diode chip 500 may, for example, have a size of 1 µm × 10 µm or 10 µm × 100 µm. In other variants, however, the first surface 501 of the light-emitting diode chip 500 may have different dimensions or a different shape, such as a square.

[0039] Fig. 1 shows that the side surfaces 503 of the LED chip 500 are inclined at an angle 505 relative to the first surface 501. In the Fig. 1, the angle 505 is greater than 90°, so that the side surfaces 503 are oriented towards the core 200. This is also the case in the examples from Fig. 3 and Fig. 7, which are explained below. In other variants, however, the angle 505 may be less than 90°, so that the side surfaces 503 of the LED chip 500 are oriented away from the core 200. This is the case with the Fig. 4 and Fig. This is the case in the examples shown in Figure 5, which are explained below. The angle 505 can also be equal to 90°, as in the example from Fig. 6. In all variants of the optoelectronic module 10, the angle 505 should be selected such that a maximum of the light 530 emitted at the side surfaces 503 of the LED chip 500 is coupled into the core 200 of the waveguide 110.

[0040] The following are based on Fig. 3 to 5 variants of the optoelectronic module 10 are explained, which Fig. 1 and Fig. 2 can be supplemented with a reflective box 600 formed around the light-emitting diode chip 500.

[0041] At the Fig. In the variant of the optoelectronic module 10 shown in Figure 3, the reflective box 600 comprises a first polymer 610 and a second polymer 620. The first polymer 610 is arranged in the opening 410 of the upper cladding layer 400 around the LED chip 500 and is in contact with the side surfaces 503 of the LED chip 500. The second polymer 520 is arranged around the first polymer 610 and is in contact with the first polymer 610. The second polymer 620 is also at least partially arranged in the opening 410 of the upper cladding layer 400. In this way, the opening 410 of the upper cladding layer 400 is at least partially filled with the first polymer 610 and the second polymer 620.

[0042] The first polymer 610 and the second polymer 620 have different refractive indices. It is useful if the first polymer 610 has a higher refractive index than the second polymer 620. In one example, the refractive index of the first polymer 610 matches a refractive index of the core 200, and the refractive index of the polymer 620 matches a refractive index of the upper cladding layer 400.

[0043] In the Fig. In the example shown in Figure 3, the adhesive 700 disposed between the core 200 and the first surface 510 of the LED chip 500 is also disposed between the core 200 and the first polymer 610 and between the upper cladding layer 400 and the second polymer 620. However, it may be more expedient if the second polymer 620 is in direct contact with the upper cladding layer 400 and the first polymer 610 is in direct contact with the core 200.

[0044] Light 530 emitted at the side surfaces 503 of the LED chip 500 can be reflected by total internal reflection at an interface between the first polymer 610 and the second polymer 620. Light 530 reflected at the interface can be directed toward the core 200 so that it can be coupled into the core 200.

[0045] The interface between the first polymer 610 and the second polymer 620 has a shape selected such that a large portion of light emitted at the side surfaces 503 of the light-emitting diode chip 500 is reflected at an angle that allows coupling into the core 200 of the waveguide 110.

[0046] Fig. 4 shows a variant of the optoelectronic module 10, which corresponds to the Fig. 3 shown variant. In addition to the features associated with Fig. 3, includes the Fig. 4, a metallic mirror layer 630 is arranged between the first polymer 610 and the second polymer 620. The metallic mirror layer 630 serves to reflect light 530 emitted at the side surfaces 503 of the LED chip 500 toward the core 200, so that the reflected light 530 can be coupled into the core 200 of the waveguide 110. Compared to the variant shown in Fig. In the variant of the optoelectronic module 10 shown in Figure 3, the metallic mirror layer 630 can also reflect light 530 that is incident at an angle outside the angular range for which total reflection occurs.

[0047] The optoelectronic module 10 from Fig. 4 additionally includes a metallic mirror layer 310 disposed between the lower cladding layer 300 and the core 200 beneath the LED chip 500. The metallic mirror layer 310 can serve to reflect light 530 that reaches the core 200 at an angle of incidence outside the angular range accepted by the core 200 and, accordingly, passes through the core 200. Light 530 reflected by the metallic mirror layer 310 is given another chance to be coupled into the core 200 of the waveguide 110. This is useful if the metallic mirror layer 310 is larger than the LED chip 500 in the longitudinal direction 111.

[0048] The Fig. The optoelectronic module 10 shown in Figure 4 also differs from the one shown in Fig. 3 is that the angle 505 between the first surface 501 and the side surfaces 503 of the LED chip 500 is less than 90°. This angle 505 can allow portions of the light 530 emitted at the side surfaces 503 of the LED chip 500 to be reflected toward the core 200 in the first polymer 610, so that this light 530 is coupled directly into the core 200 of the waveguide 110.

[0049] Another difference between Fig. 3 and Fig. 4 is that in the Fig. 4, the adhesive 700 is arranged only between the core 200 and the light-emitting diode chip 500, but not under the first polymer 610 and the second polymer 620.

[0050] In other variants of the optoelectronic module 10, the Fig. 3 shown variant of the optoelectronic module 10 can be supplemented with one or some of the additional features that can be used in conjunction with Fig. 4 described above.

[0051] Fig. 5 shows a variant of the optoelectronic module 10, wherein the reflective box 600 comprises a metallic mirror layer 660 arranged on the second surface 502 and the side surfaces 503 of the LED chip 500. A passivation layer 650 can be arranged between the second surface 502 and the side surfaces 503 beneath the metallic mirror layer 660 to prevent electrical short circuits. The metallic mirror layer 660 can be referred to as a Monte Bianco mirror. The metallic mirror layer 660 serves to reflect light 530 emitted at the second surface 502 and the side surfaces 503 toward the core 200, so that reflected light can be coupled into the core 200 of the waveguide 110.

[0052] A polymer 670 is disposed around the LED chip 500 in the opening 410 of the upper cladding layer 400 to at least partially fill the opening 410. The polymer 670 may have a refractive index that matches, for example, the refractive index of the upper cladding layer 400 and may serve to complete the upper cladding layer 400. The polymer 670 may be omitted.

[0053] In the Fig. In the example shown in Figure 5, the adhesive 700 disposed between the core 200 and the LED chip 500 is also disposed between the polymer 670 and the upper cladding layer 400. However, it is possible to omit the adhesive 700 in the region so that the polymer 670 is in direct contact with the upper cladding layer 400.

[0054] Fig. 6 shows a schematic sectional view of another variant of the optoelectronic module 10. In this variant, the core 200 has a recess 220 in which a portion of the material of the core 200 has been removed. The recess 220 borders the opening 410 of the upper cladding layer 400. The light-emitting diode chip 500 is arranged in the recess 220. In this way, at least some portions of the light 530 emitted at the side surfaces 503 of the light-emitting diode chip 500 directly impinge on the core 200 and can be coupled into the core 200.

[0055] The Fig. The optoelectronic module 10 shown in Figure 6 can be supplemented with a reflective box 600, as in connection with Fig. 3 to 5, and may also include any of the additional features previously described with reference to Fig. 1 to 5 are described.

[0056] Fig. Figure 7 shows a variant of the optoelectronic module 10, which in conjunction with Fig. 1 and Fig. 2 is similar to the variant described in Fig. 7 additionally includes a reflective structure 420 disposed on an upper side 401 of the upper cladding layer 400. The upper side 401 of the upper cladding layer 400 is opposite the side of the upper cladding layer 400 that is in contact with the core 200. The reflective structure 420 is disposed near the light-emitting diode chip 500 around the opening 410 of the upper cladding layer 400.

[0057] The reflective structure 420 may serve to reflect light 530 emitted by the LED chip 500 toward the core 200 so that the reflected light 530 can be coupled into the core 200 of the waveguide 110. The reflective structure 420 may serve to reflect light 530 incident on the reflective structure 420 within the upper cladding layer 400, but may also serve to reflect or deflect light 530 incident on the reflective structure 420 from outside the upper cladding layer 400, so that the reflected or deflected light is directed toward the core 200. The reflective structure 420 may, for example, include a microstructure 425.

[0058] The optoelectronic module 10 from Fig. 7 additionally comprises a metallic mirror layer 320 arranged on a side of the lower cladding layer 300 opposite the side of the lower cladding layer 300 that is in contact with the core 200. The metallic mirror layer 320 serves to reflect light 530 that has not yet been coupled into the core 200 of the waveguide 110 toward the core 200, so that it has another chance to be coupled into the core 200 of the waveguide 110. In an alternative variant, the metallic mirror layer 320 can be arranged between the lower cladding layer 300 and the core 200, like the metallic mirror layer 310 shown in Fig. 4 is shown.

[0059] The Fig. The optoelectronic module 10 shown in Figure 7 can be supplemented with a reflective box 600, as in connection with Fig. 3 to 5, and may also include any of the additional features previously described with reference to Fig. 1 to 6 are explained.

[0060] The invention has been illustrated and described in more detail with the aid of the preferred embodiments. However, the invention is not limited to the disclosed examples. Rather, other variants may be derived therefrom by one skilled in the art. REFERENCE SYMBOL 10 optoelectronic module 100 photonic chips 110 waveguides 111 Longitudinal direction 200 core 210 Contact section 215 width 220 recess 300 lower mantle layer 310 metallic mirror layer 320 metallic mirror layer 400 upper mantle layer 401 top page 410 Opening 420 reflective structure 425 Microstructure 500 LED chips 501 first area 502 second area 503 side surface 504 long side 505 angles 510 electrical contact 520 active layer 530 light 600 reflective box 610 first polymer 620 second polymer 630 metallic mirror layer 650 passivation layer 660 metallic mirror layer 670 Polymer 700 Adhesive 710 scattering particles QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] FROM 10 2023 110 417.9

[0002]

Claims

[1] Optoelectronic module (10), comprising a photonic chip (100) and a light-emitting diode chip (500), wherein the light-emitting diode chip (500) comprises a first surface (501), a second surface (502) opposite the first surface (501), and side surfaces (503) extending between the first surface (501) and the second surface (502), wherein the photonic chip (100) comprises a waveguide (110), wherein the waveguide (110) comprises a core (200) arranged between a lower cladding layer (300) and an upper cladding layer (400), wherein an opening (410) is formed in the upper cladding layer (400), wherein the light-emitting diode chip (500) is arranged on the core (200) in the opening (410) such that the first surface (501) is oriented towards the core (200). [2] Optoelectronic module (10) according to claim 1, wherein a reflective box (600) is formed around the light-emitting diode chip (500). [3] Optoelectronic module (10) according to claim 2, wherein the reflective box (600) comprises a first polymer (610) and a second polymer (620) with different refractive indices, wherein the first polymer (610) is in contact with the side surfaces (503) of the light-emitting diode chip (500), wherein the second polymer (620) is arranged around the first polymer (610). [4] The optoelectronic module (10) of claim 3, wherein a refractive index of the first polymer (610) matches a refractive index of the core (200), wherein a refractive index of the second polymer (620) matches a refractive index of the upper cladding layer (400). [5] Optoelectronic module (10) according to one of claims 3 and 4, wherein a metallic mirror layer (630) is arranged between the first polymer (610) and the second polymer (620). [6] Optoelectronic module (10) according to claim 2, wherein the reflective box (600) comprises a metallic mirror layer (660) arranged on the second surface (502) and the side surfaces (503) of the light-emitting diode chip (500). [7] Optoelectronic module (10) according to one of the preceding claims, wherein a metallic mirror layer (310) is arranged between the lower cladding layer (300) and the core (200) under the light-emitting diode chip (500). [8] Optoelectronic module (10) according to one of the preceding claims, wherein the opening (410) of the upper cladding layer (400) is at least partially filled with a polymer (610, 620, 670). [9] Optoelectronic module (10) according to one of the preceding claims, wherein the core (200) has a recess (220), wherein the light-emitting diode chip (500) is arranged in the recess (220). [10] Optoelectronic module (10) according to one of the preceding the claims, wherein the core (200) comprises a contact portion (210) having a greater width (215) than adjacent portions of the core (200), wherein the light-emitting diode chip (500) is arranged on the contact portion (210) of the core (200). [11] Optoelectronic module (10) according to one of the preceding the claims, wherein a reflective structure (420) is arranged on a side (401) of the upper cladding layer (400) opposite the core (200) in a vicinity of the light-emitting diode chip (500). [12] Optoelectronic module (10) according to claim 11, wherein the reflective structure (420) comprises a microstructure (425). [13] Optoelectronic module (10) according to one of the preceding the claims, wherein electrical contacts (510) of the light-emitting diode chip (500) are arranged on the second surface (502). [14] Optoelectronic module (10) according to one of the preceding the claims, wherein the first surface (501) of the light-emitting diode chip (500) has a rectangular shape, wherein longitudinal sides (504) of the first surface (501) are oriented parallel to a longitudinal direction (111) of the waveguide (110). [15] Optoelectronic module (10) according to one of the preceding the claims, wherein the side surfaces (503) of the light-emitting diode chip (500) are inclined at an angle (505) different from 90° relative to the first surface (501). [16] Optoelectronic module (10) according to one of the preceding the claims, wherein an adhesive (700) is arranged between the core (200) and the first surface (501) of the light-emitting diode chip (500). [17] Optoelectronic module (10) according to claim 16, wherein the adhesive (700) comprises scattering particles (710).

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