Silicon-based on-chip light source integrated with an end-face coupler

Abstract

The present invention discloses a silicon-based on-chip light source integrated with an end-face coupler, which includes an inverted-ridge waveguide silicon-based laser and an end-face coupler. Among them, the inverted-ridge waveguide silicon-based laser includes: a substrate, the substrate forms a beam located in the middle section of the substrate through a rectangular groove, and a first plane and a second plane located at both ends of the substrate, and a communication trench is provided on the first plane; an inverted-ridge waveguide microwire, the inverted-ridge waveguide microwire is arranged in the communication trench, and the inverted-ridge waveguide microwire is provided with a waveguide layer; a dielectric filling layer, covering the inverted-ridge waveguide microwire; the end-face coupler includes: a silicon waveguide, arranged on the second plane and the beam, and corresponding to the inverted-ridge waveguide microwire; a dielectric waveguide, covering the beam, and the dielectric waveguide is in contact with the inverted-ridge waveguide microwire; an electrode, including an upper electrode and a lower electrode, the upper electrode is arranged on the dielectric filling layer and is in contact with the inverted-ridge waveguide microwire, and the lower electrode is in contact with the substrate.

Description

Technical Field

[0001] The present invention relates to the field of silicon-based optoelectronic integration, and particularly to a silicon-based on-chip light source integrated with an end-face coupler. Background Art

[0002] With the improvement of the integration degree of integrated circuits, the bandwidth, power consumption, speed, time delay, etc. of devices cannot develop as expected. At present, silicon-based optoelectronic integration technology has become an inevitable trend in the development of information technology and a common consensus in the industry. Silicon-based selective area epitaxial lasers are considered an ideal on-chip light source for optical dense integration. Since silicon is an indirect bandgap material, an effective silicon-based light source has always been a major problem in silicon-based optoelectronic dense integration. The coupling between silicon-based selective area epitaxial lasers and silicon waveguides is very crucial, and there is currently no standard coupling scheme. Summary of the Invention

[0003] Based on this, the present invention proposes a silicon-based on-chip light source integrated with an end-face coupler, which has the advantages of high alignment accuracy, low cost, batch production feasibility, easy implementation, and optical dense integration capability.

[0004] According to one aspect of the present invention, there is provided a silicon-based on-chip light source integrated with an end-face coupler, comprising an inverted-ridge waveguide silicon-based laser and an end-face coupler;

[0005] The above-mentioned inverted-ridge waveguide silicon-based laser includes:

[0006] A substrate, the substrate forms a beam located in the middle section of the substrate through the above-mentioned rectangular groove, and

[0007] A first plane and a second plane located at both ends of the substrate, a communication trench is provided on the first plane;

[0008] An inverted-ridge waveguide micro wire, the inverted-ridge waveguide micro wire is arranged in the above-mentioned communication trench;

[0009] A dielectric filling layer, covering the above-mentioned inverted-ridge waveguide micro wire;

[0010] The above-mentioned end-face coupler includes:

[0011] A silicon waveguide, arranged on the second plane and the beam, and corresponding to the above-mentioned inverted-ridge waveguide micro wire;

[0012] A dielectric waveguide, covering the beam, and the dielectric waveguide is in contact with the above-mentioned inverted-ridge waveguide micro

[0013] wire;

[0014] An electrode, including an upper electrode and a lower electrode, the upper electrode is arranged on the above-mentioned dielectric filling layer and is in contact with the above-mentioned inverted-ridge waveguide micro wire, and the lower electrode is in contact with the substrate.

[0015] According to an embodiment of the present invention, the silicon waveguide includes a connected tapered silicon waveguide and a straight silicon waveguide, and the straight silicon waveguide serves as an output end of an on-chip optical transmitter and is connected to a silicon photonic chip.

[0016] According to an embodiment of the present invention, the dielectric waveguide wraps the tapered silicon waveguide.

[0017] According to an embodiment of the present invention, the length of the dielectric waveguide is not less than the length of the tapered silicon waveguide covered by the dielectric waveguide.

[0018] According to an embodiment of the present invention, the material of the dielectric waveguide is SiN x , SiO x N y , BCB, SiO2 or more.

[0019] According to an embodiment of the present invention, the substrate includes a silicon bottom layer and a buried oxide layer, an etched structure covering the beam is formed on the buried oxide layer, the silicon bottom layer below the beam is etched to form a cavity penetrating the rectangular groove, and a cantilever structure serving as the beam is formed through the rectangular groove and the cavity.

[0020] According to an embodiment of the present invention, the connecting grooves include rectangular silicon dioxide grooves formed in the buried oxide layer and V-shaped grooves formed in the silicon bottom layer;

[0021] The aspect ratio of the rectangular silicon dioxide trench is greater than 2.

[0022] According to an embodiment of the present invention, the inverted ridge waveguide microwire is provided with a waveguide layer, and the lower end of the waveguide layer is in contact with the inner wall of the rectangular silicon dioxide groove.

[0023] According to an embodiment of the present invention, the silicon bottom layer is an N-type heavily doped silicon layer.

[0024] According to an embodiment of the present invention, the beam has the same width as the dielectric waveguide, and the width of the beam is greater than the width of the connecting groove.

[0025] It can be seen from the above technical solution that the silicon-based light source with integrated end-face coupler provided by the present invention has the following beneficial effects:

[0026] The present invention designs an inverted ridge waveguide laser and an end coupler on the same substrate. The inverted ridge waveguide laser is prepared by selective area epitaxy, and a silicon-based light source solution that can be coupled into a silicon waveguide is provided. The light-emitting surface and the silicon waveguide are in the same plane, which is beneficial to improving the coupling efficiency of light from the laser to the silicon waveguide.

[0027] The silicon-on-chip light source integrated with an end-face coupler provided by the present invention has beams and connecting trenches fabricated in a silicon dioxide layer, and this structure greatly increases the stability of the cantilever structure. It has the advantages of high alignment accuracy, low cost, mass producibility, easy implementation, and optical dense integration, etc., providing an optional silicon-based light source solution for optical dense integration. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of the silicon-on-chip light source integrated with an end-face coupler according to an embodiment of the present invention;

[0029] Figure 2 It is a schematic cross-sectional diagram of the silicon-on-chip light source integrated with an end-face coupler according to an embodiment of the present invention;

[0030] Figure 3 It is a top view schematic diagram of a silicon waveguide and a dielectric waveguide according to an embodiment of the present invention;

[0031] Figure 4 It is a schematic cross-sectional diagram of two dielectric waveguide structures according to an embodiment of the present invention;

[0032] Figure 5 It is a schematic structural diagram of a buried oxide layer according to an embodiment of the present invention;

[0033] Figure 6 It is a schematic structural diagram of a lower electrode fabricated on the lower surface of a silicon bottom layer of a substrate according to an embodiment of the present invention;

[0034] Figure 7 It is a schematic structural diagram of a lower electrode fabricated on the upper surface of an extended portion of a silicon bottom layer of a substrate according to an embodiment of the present invention.

[0035] Reference Numerals:

[0036] 1 - Substrate;

[0037] 101 - Silicon bottom layer; 102 - Buried oxide layer; 103 - Etching structure; 104 - Beam;

[0038] 2 - Inverted ridge waveguide microwire;

[0039] 201 - Waveguide layer;

[0040] 3 - Dielectric waveguide;

[0041] 301 - Low refractive index dielectric waveguide; 302 - High refractive index dielectric waveguide;

[0042] 4 - Silicon waveguide;

[0043] 401 - Tapered silicon waveguide; 402 - Straight silicon waveguide;

[0044] 5 - Lower electrode;

[0045] 6 - Power - on stage;

[0046] 7 - Dielectric filling layer. Detailed implementation mode

[0047] To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0048] Currently, silicon - based optoelectronic integration technology has become an inevitable trend in the development of information technology and a common consensus in the industry. Silicon - based selective - area - epitaxy lasers are considered an ideal on - chip light source for optical dense integration. Since silicon is an indirect bandgap material, an effective silicon - based light source has always been a major problem in silicon - based optoelectronic dense integration. The coupling between a silicon - based selective - area - epitaxy laser and a silicon waveguide is very crucial, and there is currently no standard coupling scheme.

[0049] Figure 1 Schematic structural diagram of a silicon - based on - chip light source of an integrated end - face coupler according to an embodiment of the present invention.

[0050] Figure 2 Schematic cross - sectional diagram of a silicon - based on - chip light source of an integrated end - face coupler according to an embodiment of the present invention.

[0051] According to the general inventive concept of one aspect of the present invention, as Figure 1 and Figure 2 shown, a silicon - based on - chip light source with an integrated end - face coupler is provided, including an inverted - ridge - type waveguide silicon - based laser and an end - face coupler;

[0052] The inverted - ridge - type waveguide silicon - based laser includes:

[0053] Substrate 1, on which a beam 104 located in the middle section of Substrate 1 and a first plane and a second plane located at both ends of Substrate 1 are formed through a rectangular groove. A communication trench is provided on the first plane;

[0054] Inverted - ridge - type waveguide microwire 2, which is arranged in the communication trench;

[0055] Dielectric filling layer 7, covering the inverted - ridge - type waveguide microwire 2;

[0056] The end - face coupler includes:

[0057] Silicon waveguide 4, which is arranged on the second plane and the beam 104, and is correspondingly arranged with the inverted - ridge - type waveguide microwire 2;

[0058] Dielectric waveguide 3, which covers the beam 104 and is in contact with the inverted - ridge - type waveguide microwire 2;

[0059] The electrodes include an upper electrode 6 and a lower electrode 5 . The upper electrode 6 is disposed on the dielectric filling layer 7 and contacts the inverted ridge waveguide microwire 2 . The lower electrode 5 contacts the substrate 1 .

[0060] The present invention designs an inverted ridge waveguide laser and an end face coupler on the same substrate 1. By designing the inverted ridge waveguide laser and the end face coupler on the same substrate 1, the inverted ridge waveguide laser can be coupled to the silicon substrate of the silicon waveguide 4, and a silicon substrate light source solution that can be coupled to the silicon waveguide 4 is provided. The light emitting surface and the silicon waveguide 4 are in the same plane, which is conducive to the coupling of light from the laser to the silicon waveguide 4.

[0061] The silicon-based on-chip light source with integrated end-face coupler provided by the present invention further adopts the method of processing beam 104 and connecting grooves on substrate 1 to make the silicon waveguide 4 and submicron wire have no alignment error, so as to realize the coupling between silicon-based selective epitaxial laser and silicon waveguide 4. It has the advantages of high alignment accuracy, low cost, batch production, easy implementation, and light-intensive integration. It provides an optional silicon-based light source solution for light-intensive integration.

[0062] According to the embodiment of the present invention, the dielectric filling layer 7 is used to flatten the top of the inverted ridge waveguide microwire 2 , so as to facilitate the preparation and support of the upper electrode 6 .

[0063] Figure 3 FIG. 4 is a schematic top view of a silicon waveguide 4 and a dielectric waveguide 3 according to an embodiment of the present invention.

[0064] According to an embodiment of the present invention, Figure 3 As shown, the silicon waveguide 4 includes a connected tapered waveguide 401 and a straight silicon waveguide 402. The straight silicon waveguide 402 serves as the output end of the on-chip optical transmitter and is connected to the silicon photonic chip.

[0065] According to an embodiment of the present invention, the dielectric waveguide 3 wraps the tapered waveguide 401 .

[0066] The dielectric waveguide 3 and the tapered waveguide 401 jointly reduce the mode conversion loss to reduce the coupling loss.

[0067] According to an embodiment of the present invention, the tapered waveguide 401 is a tapered structure formed of one material or a plurality of overlapping tapered layers formed of one or more materials, so as to reduce coupling loss.

[0068] According to an embodiment of the present invention, the length of the dielectric waveguide 3 is not less than the length of the tapered waveguide 401 covered by it.

[0069] According to the embodiment of the present invention, the dielectric waveguide 3 is located on the upper surface of the buried oxide layer 102 and completely wraps the tapered waveguide 401 . The silicon waveguide 4 is connected to the inverted ridge waveguide microwire 2 through the dielectric waveguide 3 .

[0070] According to an embodiment of the present invention, the beam 104 has the same width as the dielectric waveguide 3, so as to reduce the substrate 1 leakage loss caused by the buried oxide layer 102 while supporting the dielectric waveguide 3 and the tapered waveguide 401.

[0071] The tapered waveguide 401 and a part of the dielectric waveguide 3 covered thereon form an end-face coupler to realize the connection between the silicon waveguide 4 and the inverted-ridge waveguide laser, and improve the mode field matching degree between the two.

[0072] Figure 4 Two dielectric waveguide structures are schematically shown.

[0073] Figure 4 (a) is a dielectric waveguide composed of one material;

[0074] Figure 4 (b) is a dielectric waveguide composed of two materials.

[0075] As Figure 4 shown, according to an embodiment of the present invention, wherein the material of the dielectric waveguide 3 is one or more of SiN x , SiO x N y , BCB, SiO2.

[0076] According to an embodiment of the present invention, the dielectric waveguide 3 can adopt a low-refractive-index dielectric waveguide 301 to wrap a high-refractive-index dielectric waveguide 302.

[0077] By adopting the low-refractive-index dielectric waveguide 301 and the high-refractive-index dielectric waveguide 302 to jointly form the dielectric waveguide 3, the coupling loss can be reduced, and the high-refractive-index dielectric waveguide 302 confines the optical field in the waveguide. Compared with the overall dielectric waveguide 3, the multi-layer dielectric waveguide 3 is more complex to fabricate, but has a higher mode conversion efficiency.

[0078] Figure 5 It is a schematic structural diagram of the buried oxide layer 102 according to an embodiment of the present invention.

[0079] According to an embodiment of the present invention, wherein the substrate 1 includes a silicon bottom layer 101 and a buried oxide layer 102. An etching structure 103 covering the beam 104 is formed on the buried oxide layer 102. The silicon bottom layer 101 below the beam 104 is etched to form a cavity communicating with a rectangular groove, and a cantilever structure serving as the beam 104 is formed through the rectangular groove and the cavity.

[0080] According to an embodiment of the present invention, the silicon bottom layer 101 is the bottom silicon of an SOI substrate, and the buried oxide layer 102 is the box layer of the SOI substrate formed by silicon dioxide.

[0081] As Figure 5As shown, by forming an etching structure 103 covering the beam 104 on the buried oxide layer 102, the part of the buried oxide layer 102 with the etching structure 103 can be used as the lower cladding of the end-face coupler to reduce the coupling loss, while supporting the silicon waveguide 4 and increasing the structural stability.

[0082] Compared with separately preparing the lower cladding and the silicon dioxide layer serving as the buried oxide layer 102, the integration of the buried oxide layer and the lower cladding greatly increases the stability of the cantilever structure.

[0083] By etching the buried oxide layer 102 and the silicon bottom layer 101 with a rectangular groove, and the etching depth is lower than that of the connecting trench, a cantilever structure serving as the beam 104 is formed to avoid the leakage loss caused by the silicon bottom layer 101.

[0084] Figure 6 This is a schematic structural diagram of the lower electrode of the embodiment of the present invention prepared on the lower surface of the silicon bottom layer of the substrate.

[0085] Figure 7 This is a schematic structural diagram of the lower electrode of the embodiment of the present invention prepared on the upper surface of the extended part of the silicon bottom layer of the substrate.

[0086] According to an embodiment of the present invention, as shown in Figure 6 and Figure 7 shown, the upper electrode 6 is prepared on the upper surface of the inverted ridge waveguide micro wire 2, and the lower electrode 5 is prepared on the lower surface of the silicon bottom layer 101 of the substrate 1 or by extending the area of the silicon bottom layer 101, the lower electrode 5 is arranged on the upper surface of the extended part of the silicon bottom layer 101.

[0087] According to an embodiment of the present invention, wherein, the connecting trench includes a rectangular silicon dioxide trench prepared on the buried oxide layer 102 and a V-shaped trench prepared on the silicon bottom layer 101;

[0088] The aspect ratio of the rectangular silicon dioxide trench is greater than 2.

[0089] The aspect ratio of the rectangular silicon dioxide trench is greater than 2, which is used to limit dislocations and obtain a high-quality inverted ridge waveguide micro wire 2.

[0090] According to an embodiment of the present invention, wherein, the inverted ridge waveguide micro wire 2 is provided with a waveguide layer 201, and the lower end of the waveguide layer 201 is in contact with the inner wall of the rectangular silicon dioxide trench.

[0091] According to an embodiment of the present invention, wherein, the silicon bottom layer 101 is an N-type heavily doped silicon layer, serving as the N electrode contact layer.

[0092] According to an embodiment of the present invention, wherein, the beam 104 has the same width as the dielectric waveguide 3, and the width of the beam 104 is greater than the width of the connecting trench.

[0093] The silicon-based on-chip light source integrated with an end-face coupler provided by the present invention can be completely fabricated through optoelectronic processes. The alignment of the silicon waveguide 4 and the inverted-ridge waveguide microwire 2 can be achieved by one-step lithography, ensuring zero alignment error, with high alignment accuracy, low cost, batch production feasibility, easy implementation, and the ability to perform optical dense integration. Through appropriate process design, the preparation of the silicon waveguide 4 and the connecting trench can be realized by one-step lithography, so that there is no alignment error between the silicon waveguide 4 and the submicron wire serving as the inverted-ridge waveguide microwire 2. This embodiment has the advantages of high alignment accuracy, low cost, and batch production feasibility by integrating optoelectronic processes and selecting epitaxy and controlling process errors, providing an alternative silicon-based light source solution for optical dense integration.

[0094] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A silicon-based on-chip light source with an integrated end coupler, comprising an inverted ridge waveguide silicon-based laser and an end coupler on the same substrate; The inverted ridge waveguide silicon-based laser comprises: The substrate is formed by a rectangular groove to form a beam located in the middle of the substrate, and a first plane and a second plane located at two ends of the substrate, the first plane is provided with a connecting groove, the substrate comprises a silicon bottom layer and a buried oxide layer, an etched structure covering the beam is formed on the buried oxide layer, the silicon bottom layer under the beam is etched to form a cavity penetrating the rectangular groove, and a cantilever structure as the beam is formed through the rectangular groove and the cavity; An inverted ridge waveguide microwire, wherein the inverted ridge waveguide microwire is arranged in the connecting groove; A dielectric filling layer covering the inverted ridge waveguide microwire; The end coupler comprises: A silicon waveguide is arranged on the second plane and the beam, and is arranged corresponding to the inverted ridge waveguide micron line, and the alignment of the silicon waveguide and the inverted ridge waveguide micron line is achieved by one-step photolithography; A dielectric waveguide is covered on the beam, the beam and the dielectric waveguide have the same width, and the dielectric waveguide is in contact with the inverted ridge waveguide micrometer line; The electrode comprises an upper electrode and a lower electrode, wherein the upper electrode is arranged on the dielectric filling layer and contacts the inverted ridge waveguide micrometer line, and the lower electrode contacts the substrate.

2. The light source according to claim 1, wherein, The silicon waveguide includes a connected tapered silicon waveguide and a straight silicon waveguide. The straight silicon waveguide serves as an output end of an on-chip light transmitter and is connected to a silicon photonic chip.

3. The light source according to claim 2, wherein, The dielectric waveguide wraps the tapered silicon waveguide.

4. The light source according to claim 2, wherein, The length of the dielectric waveguide is not less than the length of the tapered silicon waveguide it covers.

5. The light source according to claim 1, wherein The material of the dielectric waveguide is SiN x , SiO x N y , BCB, one or more of SiO2.

6. The light source according to claim 1, wherein, The connecting grooves include rectangular silicon dioxide grooves formed in the buried oxide layer and V-shaped grooves formed in the silicon bottom layer; The aspect ratio of the rectangular silicon dioxide trench is greater than 2.

7. The light source according to claim 6, wherein, The inverted ridge waveguide microwire is provided with a waveguide layer, and the lower end of the waveguide layer is in contact with the inner wall of the rectangular silicon dioxide groove.

8. The light source according to claim 1, wherein, The silicon bottom layer is an N-type heavily doped silicon layer.

9. The light source according to claim 1, wherein, The width of the beam is greater than the width of the connecting groove.

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