Highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure and preparation method

Abstract

The present invention discloses a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure and a preparation method, wherein the device structure includes: a substrate layer, including a silicon substrate layer and a buried oxide SIO2 layer; a silicon waveguide, located on the substrate layer, including a first silicon waveguide part and a second silicon waveguide part, arranged along a preset direction, and a preset distance between the first silicon waveguide part and the second silicon waveguide part; a semiconductor optical amplifier, a slot structure with a preset height is provided at the bottom, so that the semiconductor optical amplifier is buckled above the first waveguide part, the second waveguide part and the gap between the two through the slot walls on both sides of the slot structure; the width of the slot is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide; a cover layer, located on the semiconductor optical amplifier, is used to integrate SOA and silicon waveguide, and protect the semiconductor optical amplifier from water and oxygen in the atmosphere. In this scheme, the integration process is relatively simple, and there is no waste of SOA epitaxial materials.

Description

Technical Field

[0001] The present invention relates to the field of integrated optical technology, and in particular to a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure and a preparation method thereof. Background Art

[0002] Silicon-based photonic chips are compatible with standard semiconductor processes and have the advantages of low cost, mature process, and high integration. They are widely used in the industry. Semiconductor optical amplifiers (SOAs) are optoelectronic devices that use III-V semiconductor materials as gain to amplify or provide gain to external photons. Silicon-based integrated SOAs can amplify weak optical signals in silicon-based photonic chip circuits and are indispensable devices in silicon-based photonic chip circuits. When the signal is transmitted in multiple optical devices, SOAs can increase the output optical power and keep the signal power level stable. However, due to the different crystal structures and properties of SOA and silicon-based materials, there is a large lattice mismatch and thermal expansion coefficient mismatch between the two, and SOA devices cannot be directly prepared on silicon. Therefore, SOA and silicon-based photonic chips can only be hybrid integrated through heterogeneous bonding to increase the optical signal in the silicon-based optical chip circuit.

[0003] At present, there are two main methods for integrating SOA on silicon substrates: one is to integrate SOA devices directly on silicon photonic chips through flip-chip bonding; the other is to integrate SOA epitaxial thin film materials onto the surface of silicon photonic chips through wafer bonding, such as polymer benzocyclobutene (BCB) or polished silicon dioxide (SiO2).

[0004] Although the flip-chip bonding technology is relatively mature and can fully utilize the optical gain characteristics of SOA, it requires extremely high alignment accuracy between the two, and has high requirements on the accuracy and cost of the equipment. In particular, the SOA and silicon waveguide must undergo mode conversion to achieve the transmission of optical signals from silicon waveguide to SOA, which in turn leads to the complexity of the integration process.

[0005] By integrating SOA epitaxial thin film materials onto the surface of silicon photonic chips through wafer bonding, epitaxial layers of III-V materials can be integrated onto silicon photonic devices such as silicon waveguides. Light generated by III-V materials enters the silicon waveguide through evanescent wave coupling, completing the hybrid integration of on-chip SOA and silicon photonic chips. However, since only large-area epitaxial thin film materials can be integrated onto the surface of silicon photonic chips, the surface flatness of silicon photonic chips is very high. Therefore, the fewer device structures on the silicon substrate before integration, the better. After integration, the silicon substrate is structurally prepared, which not only increases the difficulty of the process but also wastes a large amount of SOA epitaxial materials, further increasing costs.

[0006] In summary, the existing technical solutions lack a semiconductor optical amplifier integration technical solution with a simple integration process and without wasting SOA epitaxial materials and increasing costs. Summary of the invention

[0007] The present invention provides a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure and a preparation method, which effectively solves the problem in the prior art of lacking a semiconductor optical amplifier integration technology solution with a simple integration process and no waste of SOA epitaxial materials leading to increased costs.

[0008] In a first aspect, according to an embodiment of the present invention, there is provided a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, comprising:

[0009] A substrate layer, comprising a silicon substrate layer and a buried oxide SIO2 layer located on the silicon substrate layer;

[0010] A silicon waveguide, located on the substrate layer, the silicon waveguide comprising a first silicon waveguide portion and a second silicon waveguide portion, the first silicon waveguide portion and the second silicon waveguide portion are arranged along a preset direction, and the first silicon waveguide portion and the second silicon waveguide portion are spaced a preset distance apart;

[0011] A semiconductor optical amplifier, wherein a base at the bottom is provided with a slot structure of a preset height in the length direction, so that the semiconductor optical amplifier is buckled above the first waveguide part, the second waveguide part and the gap therebetween through the slot walls on both sides of the slot structure; the width of the slot is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide; the length direction is the direction of propagation of the optical signal in the silicon waveguide;

[0012] The cover layer is located on the semiconductor optical amplifier and is used for integrating the SOA with the silicon waveguide and protecting the semiconductor optical amplifier from the attack of water and oxygen in the atmosphere.

[0013] Preferably, the thickness of the two groove walls of the slot is half of the width of the slot, the width of the slot is w-10w, and the height of the slot is h-10h; wherein w is the width of the silicon waveguide, and h is the height of the silicon waveguide.

[0014] Preferably, the spacing between the first waveguide portion and the second waveguide portion is 4-6 μm.

[0015] Preferably, a first tapered gradual-change structure and a second tapered gradual-change structure are respectively provided at two ends of the semiconductor optical amplifier in the length direction.

[0016] Preferably, the distance from the bottom of the first tapered gradual change structure to the top of the tip is 6 μm; the distance from the bottom of the second tapered gradual change structure to the top of the tip is 6 μm.

[0017] Preferably, a third tapered tapered structure is provided at the end of the first silicon waveguide portion close to the second silicon waveguide portion, a fourth tapered tapered structure is provided at the end of the second silicon waveguide portion close to the first silicon waveguide portion, and a tip portion of the third tapered tapered structure is opposite to a tip portion of the fourth tapered tapered structure.

[0018] Preferably, the distance between the tip of the third tapered gradual change structure and the tip of the fourth tapered gradual change structure is no more than 0.5 μm.

[0019] Preferably, the distance from the bottom of the third tapered gradual change structure to the top of the tip is 2.5 μm; the distance from the bottom of the fourth tapered gradual change structure to the top of the tip is 2.5 μm.

[0020] Preferably, the shape of the end of the card slot includes a rectangle, a triangle, or a polygon.

[0021] In a second aspect, according to an embodiment of the present invention, a method for preparing a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure is provided, comprising:

[0022] Providing a substrate layer, the substrate layer comprising a silicon substrate layer and a buried oxide SIO2 layer located on the silicon substrate layer;

[0023] A silicon waveguide including a first silicon waveguide portion and a second silicon waveguide portion is prepared on the buried oxide SIO2 layer in the substrate layer; the first silicon waveguide portion and the second silicon waveguide portion are arranged along a preset direction, and a preset distance is spaced between the first silicon waveguide portion and the second silicon waveguide portion;

[0024] A semiconductor optical amplifier is provided, wherein a slot structure with a preset height is provided on a bottom substrate of the semiconductor optical amplifier in a length direction, and the semiconductor optical amplifier is buckled above the first waveguide portion, the second waveguide portion and the gap therebetween through slot walls on both sides of the slot structure; the width of the slot structure is not less than the width of the silicon waveguide, and the height of the slot structure is not less than the thickness of the silicon waveguide;

[0025] A covering layer is prepared on the semiconductor optical amplifier by adopting PECVD process, which is used for integrating SOA and silicon waveguide and protecting the semiconductor optical amplifier from water and oxygen in the atmosphere.

[0026] This embodiment provides a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure and preparation method. A slot structure of a preset height is provided on the base layer at the bottom of the semiconductor optical amplifier, and then the semiconductor optical amplifier is buckled above the first waveguide part, the second waveguide part and the gap between the two through the slot walls on both sides of the slot structure, which can effectively improve the alignment accuracy of the semiconductor optical amplifier and the silicon waveguide, and the SiO2 film formed by the PECVD process realizes the integration of the semiconductor optical amplifier and the silicon waveguide. It can be seen that the integration process of this scheme is relatively simple, and there is no waste of SOA epitaxial material. In addition, due to the limiting effect of the slot on the silicon waveguide optical signal, the optical coupling efficiency of the silicon waveguide and the semiconductor optical amplifier can be significantly improved. In addition, in this scheme, the silicon waveguide in the overlap area with the SOA includes a first silicon waveguide part and a second silicon waveguide part separated by a preset distance. Compared with a silicon waveguide below, this scheme can avoid the optical signal being directly transmitted through the silicon waveguide below the SOA and not being amplified, so that all the optical signals in the silicon waveguide are transitioned to the SOA for amplification and transmission.

[0027] In addition, in this solution, a first tapered gradient structure and a second tapered gradient structure are provided at both ends of the device layer of the semiconductor optical amplifier in the length direction, which effectively improves the coupling rate between the silicon waveguide and the semiconductor optical amplifier SOA.

[0028] A third tapered gradient structure is provided at the end of the first silicon waveguide portion close to the second silicon waveguide portion, and a fourth tapered gradient structure is provided at the end of the second silicon waveguide portion close to the first silicon waveguide portion, which effectively guides the optical signal in the first silicon waveguide to be coupled into the semiconductor optical amplifier SOA.

[0029] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A schematic diagram of a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure provided by an embodiment of the present invention;

[0032] Figure 2ais a schematic diagram showing that the distance between the first silicon waveguide portion and the second silicon waveguide portion is 5 μm when both the first silicon waveguide portion and the second silicon waveguide portion have no tapered structure;

[0033] Figure 2b for Figure 2a Schematic diagram of the electric field distribution of the corresponding structure AA section;

[0034] Figure 2c for Figure 2a Schematic diagram of the electric field distribution of the corresponding structure BB section;

[0035] Figure 2d for Figure 2a Schematic diagram of the electric field distribution of the corresponding structure CC section;

[0036] Figure 3a It is a schematic diagram of the integrated structure of a semiconductor optical amplifier and a silicon waveguide without a slot structure and a tapered structure;

[0037] Figure 3b for Figure 3a Schematic diagram of the electric field distribution of the corresponding structure AA section;

[0038] Figure 3c for Figure 3a Schematic diagram of the electric field distribution of the corresponding structure BB section;

[0039] Figure 3d for Figure 3a Schematic diagram of the electric field distribution of the corresponding structure CC section;

[0040] Figure 4a It is a schematic diagram of the integrated structure of a semiconductor optical amplifier with a card slot structure but no tapered structure and a silicon waveguide;

[0041] Figure 4b for Figure 4a Schematic diagram of the electric field distribution of the corresponding structure AA section;

[0042] Figure 4c for Figure 4a Schematic diagram of the electric field distribution of the corresponding structure BB section;

[0043] Figure 4d for Figure 4a Schematic diagram of the electric field distribution of the corresponding structure CC section;

[0044] Figure 5a is a graph showing the relationship between the coupling efficiency between the semiconductor optical amplifier SOA and the silicon waveguide and the width of the card slot;

[0045] Figure 5b is a graph showing the relationship between the coupling efficiency between the semiconductor optical amplifier SOA and the silicon waveguide and the depth of the card slot;

[0046] Figure 6 It is a schematic structural diagram of a semiconductor optical amplifier SOA having a first tapered structure and a second tapered structure;

[0047] Figure 7a A schematic diagram of a structure in which a gradual tapered structure is provided at each end of the SOA, and the distance from the bottom to the tip of the gradual tapered structure is 6 μm;

[0048] Figure 7b for Figure 7a Schematic diagram of the electric field distribution of the corresponding structure AA section;

[0049] Figure 7c for Figure 7a Schematic diagram of the electric field distribution of the corresponding structure BB section;

[0050] Figure 7d for Figure 7a Schematic diagram of the electric field distribution of the corresponding structure CC section;

[0051] Figure 8a A schematic diagram of a structure in which a third gradually tapered structure is provided at an end of the first silicon waveguide portion close to the second silicon waveguide portion, a fourth gradually tapered structure is provided at an end of the second silicon waveguide portion close to the first silicon waveguide portion, and the distances from the bottom to the tip top of the third and fourth gradually tapered structures are both 2.5 μm;

[0052] Figure 8b for Figure 8a Schematic diagram of the electric field distribution of the corresponding structure AA section;

[0053] Figure 8c for Figure 8a Schematic diagram of the electric field distribution of the corresponding structure BB section;

[0054] Figure 8d for Figure 8a Schematic diagram of the electric field distribution of the corresponding structure CC section;

[0055] Fig. 9 The present invention is a flowchart of a method for preparing a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0057] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0058] In order to solve the problem that the semiconductor optical amplifier integration solutions in the prior art solutions are either complicated in process or waste of SOA epitaxial materials leading to increased costs, the present invention provides a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, and also provides a method for preparing the highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure.

[0059] The embodiment of the present invention provides a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, see Figure 1 As shown, the highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure comprises:

[0060] The substrate layer 11 includes a silicon substrate layer 111 and a buried oxide SIO2 layer 112 located on the silicon substrate layer 111;

[0061] A silicon waveguide 12 is located on the substrate layer 11, and the silicon waveguide 12 includes a first silicon waveguide portion 121 and a second silicon waveguide portion 122. The first silicon waveguide portion 121 and the second silicon waveguide portion 122 are arranged along a preset direction, and a preset distance is spaced between the first silicon waveguide portion 121 and the second silicon waveguide portion 122;

[0062] The semiconductor optical amplifier 13 comprises a bottom substrate and a device layer on the substrate, and a slot structure 131 of a preset height is arranged on the bottom substrate, so that the semiconductor optical amplifier is buckled above the first waveguide part 121, the second waveguide part 122 and the gap therebetween through the slot walls on both sides of the slot structure; the width of the slot structure is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide;

[0063] Covering layer( Figure 1The semiconductor optical amplifier 13, the first silicon waveguide portion, and the second silicon waveguide portion are prepared by a PECVD process to protect the semiconductor optical amplifier from water and oxygen in the atmosphere, and integrate the semiconductor optical amplifier SOA with the silicon waveguide.

[0064] In the embodiment of the present invention, the substrate layer 11 includes a supporting silicon substrate layer 111 and a buried oxide SIO2 layer 112 located on the silicon substrate layer 111 . The buried oxide SIO2 layer 112 is used to isolate the silicon waveguide 12 from the silicon substrate layer 111 .

[0065] In the embodiment of the present invention, the silicon waveguide 12 includes two independent parts, namely a first silicon waveguide part 121 and a second silicon waveguide part 122. The propagation direction of light in the first silicon waveguide part 121 and the second silicon waveguide part 122 is the same, and the two are set at a preset distance. In order to maximize the coupling efficiency between the silicon waveguide and the semiconductor optical amplifier SOA, the distance between the first silicon waveguide part 121 and the second silicon waveguide part 122 cannot be too small. By simulating the distance between the first silicon waveguide part 121 and the second silicon waveguide part 122, when the distance between the two is 0 μm, the coupling efficiency between the silicon waveguide and the semiconductor optical amplifier SOA is, and when the distance between the two is increased to 5 μm, the coupling efficiency between the silicon waveguide and the semiconductor optical amplifier SOA is increased to, therefore, as a preferred embodiment, the spacing between the first silicon waveguide part 121 and the second silicon waveguide part in this solution is 4-6 μm.

[0066] The following will be Figure 2a Taking the structure optimization and design as an example, the optical coupling efficiency between silicon waveguide and SOA is further improved. By optimizing L2, the electric field intensity at the CC section is increased from 0.653V / m when L2=0μm to 0.771V / m when L2=5μm, and the optical coupling efficiency between silicon waveguide and semiconductor optical amplifier SOA is increased by 18%. The distribution of electric field on AA, BB and CC sections is shown in the figure. Figure 2a , 2b As shown in 2c. Figure 2b and 2c It can be seen that there is no light field distribution in the silicon waveguide. Through 2d, it can be seen that the electric field strength in the semiconductor optical amplifier is significantly enhanced, which means that the optical signal is no longer transmitted through the silicon waveguide but is all transferred through the SOA, thereby achieving the purpose of amplifying all the optical signals in the silicon waveguide by the SOA.

[0067] In an embodiment of the present invention, a semiconductor optical amplifier (SOA) includes a substrate layer and a device layer. In this solution, a slot structure 131 is provided on the substrate layer of the semiconductor optical amplifier 13, so that during integration, two slot walls of the slot structure 131 are respectively provided at the first waveguide portion 121, the gap between the first waveguide portion 121 and the second silicon waveguide portion 122, and both sides of the second silicon waveguide portion 122. In this solution, the width of the slot structure 131 is not less than the width of the silicon waveguide 12, and the height of the slot structure 131 is not less than the thickness of the silicon waveguide, so that the slot structure 131 can be provided across both sides of the silicon waveguide.

[0068] In the embodiment of the present invention, a covering layer 14 is provided at least above the device layer of the semiconductor optical amplifier 13, part of the first silicon-silicon waveguide part and part of the second silicon waveguide part, wherein the covering layer is made of a SIO2 layer, which is used to integrate the semiconductor optical amplifier and the silicon waveguide, and at the same time isolate the device layer of the semiconductor optical amplifier 13 from the air, thereby protecting the device layer of the semiconductor optical amplifier 13 from the invasion of water and oxygen in the atmosphere. At the same time, the semiconductor optical amplifier and the silicon waveguide are integrated together through the covering layer 14.

[0069] In an embodiment of the present invention, the covering layer is prepared by a PECVD process, that is, after the semiconductor optical amplifier 13 with a slot is set on both sides of the silicon waveguide, the structure is sent to a plasma enhanced chemical deposition device PECVD, and a SIO2 layer is grown by the PECVD process, thereby realizing the integration of the semiconductor optical amplifier and the silicon waveguide.

[0070] In this solution, the semiconductor optical amplifier 13 is directly buckled on both sides of the silicon waveguide through a slot structure, which can effectively improve the alignment accuracy between the semiconductor optical amplifier and the silicon waveguide, and because of the limiting effect of the slot on the silicon waveguide optical signal, the optical coupling efficiency between the silicon waveguide and the semiconductor optical amplifier can be significantly improved. In addition, in this solution, the silicon waveguide in the overlap area with the SOA is designed as two silicon waveguide parts, and the first silicon waveguide part and the second silicon waveguide part are set at a preset distance, which can avoid the optical signal being directly transmitted through the silicon waveguide under the semiconductor optical amplifier SOA and not being amplified, so that all the optical signals in the silicon waveguide are transferred to the semiconductor optical amplifier SOA for amplification and transmission.

[0071] At the same time, in the process of aligning the semiconductor optical amplifier with the silicon waveguide through the slot structure 131, the two may not be fixed by any adhesive, but later, the semiconductor optical amplifier and the silicon waveguide are vacuum bonded by growing a SiO2 cover layer in PECVD. In order to improve the convenience of operation, a small amount of water vapor or liquid such as photoresist may be sprayed on the surface of the silicon waveguide or semiconductor optical amplifier to improve the adhesion between the two, and then the SiO2 cover layer is grown by the PECVD process to achieve vacuum bonding between them. This process method is simple, easy to implement, has high alignment accuracy, greatly reduces the difficulty of current silicon-based heterogeneous integration, and does not waste SOA epitaxial materials.

[0072] It is pointed out here that in order to characterize the results of electric field changes on different cross sections in the subsequent simulation processes, the positions of the cross sections where the electric field monitors are located are marked on the figure, as shown by AA, BB and CC in the figure. AA means simultaneous monitoring of the electric field changes on the cross sections where the silicon waveguide and the semiconductor optical amplifier SOA are located in the length direction; BB means simultaneous monitoring of the electric field changes on the cross sections where the silicon waveguide and the semiconductor optical amplifier SOA are located in the width direction; CC means monitoring the electric field changes on the cross section of the silicon waveguide at the other end of the semiconductor optical amplifier SOA.

[0073] Two comparative examples are listed below to illustrate the high coupling efficiency of the device structure provided by this solution:

[0074] like Figure 3a-3d As shown, it is a simulation model of the integrated structure of the semiconductor optical amplifier SOA and silicon waveguide without a slot and a taper structure, and a schematic diagram of the electric field distribution on each section AA, BB, and CC. Among them, 111 is a silicon substrate, 112 is a SiO2 buried oxide layer, and 12 is a silicon waveguide. The dimensions of the silicon waveguide are set as follows: silicon waveguide width W = 0.5μm, silicon waveguide height h = 0.22μm; the semiconductor optical amplifier adopts a forward epitaxial thin film integration solution, and the dimensions of the semiconductor optical amplifier (SOA) epitaxial film are: SOA length L1 = 10μm, SOA width W1 = 1μm, SOA height h1 = 1μm. From the AA and BB surfaces in Figures 3b and 3c, it can be clearly seen that only a small part of the optical signal is transitionally transmitted through the SOA, while most of the optical signals are directly transmitted to the other end of the SOA through the silicon waveguide. From Figure 3d From the CC surface data, we can see that the optical signal finally transmitted to the other end of the semiconductor optical amplifier SOA is only 0.291V / m (the sum of SOA transition transmission and silicon waveguide transmission). This also shows that the direct coupling efficiency between SOA and silicon waveguide is low, and most of the optical signals are scattered to the outside of SOA and silicon waveguide, resulting in the loss of optical field energy.

[0075] In order to suppress the dispersion of the light field in the silicon waveguide below the SOA and allow more optical signals to be transmitted through the SOA, this scheme proposes a slot structure designed at the bottom of the SOA to limit the dispersion of the light field in the silicon waveguide so that more optical signals can be transformed into the SOA for transitional transmission. The SOA model with a slot structure is shown in the figure. Figure 4a The electric field distribution on each cross section after simulation under the conditions of slot height h2 = 0.22 μm, slot width W3 = 0.5 μm and slot wall thickness W2 = 0.25 μm is shown in Figure 4b , 4c As shown in 4d. Figure 4b Medium AA surface and Figure 4c From the data changes on the middle BB plane, we can see that the electric field strength in the silicon waveguide below the SOA is significantly reduced, and most of the electric field is concentrated in the SOA. Figure 3a ), the SOA card slot structure design card can obviously suppress the dispersion of light in the silicon waveguide (below the SOA), so that more optical signals are guided by the card slot structure into the SOA for transition transmission. Figure 3d and Figure 4d It can be seen that the SOA slot structure can increase the optical coupling efficiency from 0.291 V / m without the slot to 0.653 V / m with the slot, and the coupling efficiency is increased by 1.24 times. Therefore, the SOA slot structure design adopted in the present invention can greatly improve the optical coupling efficiency between the two in the heterogeneous integration of SOA on a silicon substrate, thereby providing a good solution to the problem of low optical coupling efficiency in silicon-based heterogeneous integrated SOA, and has great practical application prospects.

[0076] In the embodiment of the present invention, the thickness of the two groove walls of the slot is half of the width of the slot, the width of the slot is w-10w, and the height of the slot is h-10h; wherein w is the width of the silicon waveguide, and h is the height of the silicon waveguide.

[0077] The above simulation process can significantly improve the optical coupling efficiency between SOA and silicon waveguide. However, the above simulation is based on the width of the SOA slot being the same as the width of the silicon waveguide. However, in actual application, when the spacing of the SOA slot is exactly equal to the width of the silicon waveguide (W3=W), it is difficult to achieve precise buckling between the two with the current process. Therefore, in actual application, the width W3 of the SOA slot is required to be greater than the width of the silicon waveguide, that is, W3>W. However, it cannot be infinitely large, after all, the increase in the slot width will affect the coupling efficiency. Therefore, the simulation results for the width W2 and height h2 of the SOA slot are determined by the following simulation data. Figure 5a , 5bAs shown. From the figure, we can see that they have different degrees of influence on the optical coupling efficiency between the semiconductor optical amplifier SOA and the silicon waveguide: compared with the SOA without a slot structure, when the slot width is in the range of w-10w, the slot width can increase the optical coupling efficiency between the two by more than 70%, and when the slot width W2 is equal to the width W of the silicon waveguide, the effect is best, which is increased by 1.3 times; the slot height can increase the optical coupling efficiency between the two by more than 50%, and when the slot height h2 is equal to the height h of the silicon waveguide, the effect is best, which is increased by 1.3 times. However, based on the existing process level and the simulation data diagram, the slot width is set to w-10w and the slot height is set to h-10h. In order to effectively limit the optical signal in the silicon waveguide and achieve a coupling efficiency of more than 70%, this solution selects the slot wall width as half of the slot width.

[0078] In an embodiment of the present invention, a distance between the first waveguide portion and the second waveguide portion is less than or equal to 5 μm.

[0079] In the embodiment of the present invention, although the slot structure design is adopted in the semiconductor optical amplifier SOA substrate layer to significantly improve the optical coupling efficiency between SOA and silicon waveguide, Figure 4b and 4c It can be seen that a small amount of optical signals are still directly transmitted in the first silicon waveguide part and the second silicon waveguide part under the SOA. In order to avoid the optical signals being unable to be amplified due to direct transmission through the silicon waveguide under the SOA, the present invention further adopts a discontinuous structure design of the first silicon waveguide part and the second silicon waveguide part under the SOA to block the transmission path of the optical signal in the silicon waveguide, so that all the optical signals of the silicon waveguide are transitionally transmitted through the SOA to achieve the purpose of amplifying all the optical signals by the SOA. The discontinuous design structure model of the silicon waveguide under the SOA is shown in the figure. Figure 6 As shown in FIG. 1 , as a specific embodiment, the discontinuous structure is a tapered tapered structure, such as Figure 6 shown.

[0080] like Figure 7a As shown, in an embodiment of the present invention, a first tapered gradient structure 133 and a second tapered gradient structure 134 are respectively provided at both ends of the length direction of the semiconductor optical amplifier; wherein the first tapered gradient structure 133 and the second tapered gradient structure 134 have the same shape and / or structure.

[0081] Furthermore, the distance from the bottom of the first tapered gradual change structure 133 to the top of the tip is 6 μm; the distance from the bottom of the second tapered gradual change structure 134 to the top of the tip is 6 μm.

[0082] In order to further improve the optical coupling efficiency between SOA and silicon waveguide, a tapered structure taper is designed at both ends of SOA to guide the optical signal in silicon waveguide to transition to SOA. Figure 7a As shown. By optimizing the distance L4 between the bottom and the top of the tapered structure taper, the electric field strength at the CC section is increased from 0.771V / m when L4=0μm to 0.963V / m when L4=6μm, an increase of 25%. This shows that the SOA with the taper structure design can further improve the optical coupling efficiency between it and the silicon waveguide. Figure 7b , Figure 7c The electric field data of the middle (AA) section and the (BB) section show that the optical signals in the silicon waveguide are all concentrated in the middle position of the SOA for transmission, and the optical field distribution is more concentrated. In particular, there is no optical field distribution in the silicon waveguide below the semiconductor optical amplifier SOA. This further illustrates that the semiconductor optical amplifier SOA and silicon waveguide discontinuous structure used in the present invention increases the coupling efficiency between the two to as high as 96.3%, which is close to the full-efficiency coupling level. Figure 7d As shown, it is also the highest level that heterogeneous integrated SOA on silicon substrate can achieve at present.

[0083] In the embodiment of the present invention, a third tapered gradual change structure 123 is disposed at the end of the first silicon waveguide portion close to the second silicon waveguide portion, a fourth tapered gradual change structure 124 is disposed at the end of the second silicon waveguide portion close to the first silicon waveguide portion, and the tip of the third tapered gradual change structure 123 is opposite to the tip of the fourth tapered gradual change structure 124. The third tapered gradual change structure 123 and the fourth tapered gradual change structure 124 have the same shape and / or structure.

[0084] Furthermore, the distance between the tip of the third tapered gradual change structure 123 and the tip of the fourth tapered gradual change structure 124 is less than 0.5 μm.

[0085] Furthermore, the distance from the bottom of the third tapered gradual change structure to the top of the tip is 2.5 μm; the distance from the bottom of the fourth tapered gradual change structure to the top of the tip is 2.5 μm.

[0086] In the embodiments of the present invention, further, see Figure 8aAs shown, a third tapered gradient structure 123 is provided at the end of the first silicon waveguide portion 121 close to the second silicon waveguide portion, and a fourth tapered gradient structure 124 is provided at the end of the second silicon waveguide portion 122 close to the first silicon waveguide portion. When the distance L3 from the bottom of the third and fourth tapered gradient structures to the top of the tip is 2.5 μm and when the distance L4 from the bottom of the first and second tapered gradient structures to the top of the tip is 6 μm, the optical coupling efficiency between the silicon waveguide and the SOA also reaches a full-efficiency coupling level of 96%, as shown in FIG. Figure 8b-8d shown.

[0087] In summary, the SOA slot and taper structure and the discontinuous structure design of the silicon waveguide proposed in the present invention improve the optical coupling efficiency by 2.31 times compared with the current silicon-based heteroepitaxial integration; compared with the case where the SOA has only a slot structure, the optical coupling efficiency is further improved by 47%, and all the optical signals in the silicon waveguide are transitionally transmitted through the SOA, so that all the optical signals in the silicon waveguide are amplified by the SOA. In particular, the light field distribution in the SOA is more concentrated and uniform, and there is basically no dispersion phenomenon.

[0088] In the embodiment of the present invention, the shape of the end of the card slot includes a rectangle, a triangle, and a polygon; similarly, the shape of the end of the first silicon waveguide portion close to the second silicon waveguide portion may also include a rectangle, a triangle, and a polygon. Similarly, the shape of the end of the second silicon waveguide portion close to the first silicon waveguide portion is set in the same manner. It is pointed out here that as a preferred embodiment, the cross-sectional shape of the end of the first silicon waveguide portion close to the second silicon waveguide portion can be set to be the same as the cross-sectional shape of the end of the second silicon waveguide portion close to the first silicon waveguide portion.

[0089] The present invention also provides a method for preparing a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, see Fig. 9 As shown, including:

[0090] Step S12, providing a substrate layer, wherein the substrate layer includes a silicon substrate layer and a buried oxide SIO2 layer located on the silicon substrate layer;

[0091] Step S14, preparing a silicon waveguide including a first silicon waveguide portion and a second silicon waveguide portion on the buried oxide SIO2 layer in the substrate layer; the first silicon waveguide portion and the second silicon waveguide portion are arranged along a preset direction, and the first silicon waveguide portion and the second silicon waveguide portion are spaced by a preset distance;

[0092] Step S16, providing a semiconductor optical amplifier, wherein a slot structure with a preset height is provided on a bottom substrate of the semiconductor optical amplifier in a length direction, and the semiconductor optical amplifier is buckled above the first waveguide portion, the second waveguide portion and the gap therebetween through slot walls on both sides of the slot structure; the width of the slot is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide; the length direction is the direction of propagation of the optical signal in the silicon waveguide;

[0093] Step S18: Using PECVD process to prepare a cover layer on the semiconductor optical amplifier for integrating SOA and silicon waveguide and protecting the semiconductor optical amplifier from water and oxygen in the atmosphere.

[0094] In this solution, vacuum heterogeneous bonding of SOA and silicon waveguide is achieved by growing SiO2 capping layer in PECVD, which increases the compactness of contact between SOA and silicon waveguide, is conducive to the coupling of light evanescent wave, and thus effectively improves the optical coupling efficiency between the two. The heterogeneous integrated SOA structure on silicon substrate proposed by the present invention not only makes the optical coupling efficiency between the two extremely high and the integration process simple, but also realizes vacuum bonding integration of SOA and silicon waveguide, further increases the stability between the two, and simplifies the steps of silicon-based heterogeneous integrated SOA.

[0095] Through the device structure prepared by this scheme, the semiconductor optical amplifier SOA is designed into a slot and taper structure, which can not only realize the pn forward mounting integration of the SOA but also realize the np reverse bonding integration; in addition, in the process of silicon-based heterogeneous integration of the semiconductor optical amplifier SOA, the slot structure in the semiconductor optical amplifier SOA is directly buckled on both sides of the silicon waveguide, which can effectively improve the alignment accuracy between the SOA and the silicon waveguide, and due to the limiting effect of the slot structure on the silicon waveguide optical signal, the optical coupling efficiency between the two can be significantly improved.

[0096] It is pointed out here that this embodiment is a preparation method embodiment corresponding to the device structure in the previous embodiment. The technical content disclosed in the device structure is also applicable in the preparation method embodiment. Similarly, the content provided in the preparation method embodiment is also applicable in the device structure embodiment. In order to avoid repetition, it will not be repeated here.

[0097] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0098] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, characterized in that: include: A substrate layer, comprising a silicon substrate layer and a buried oxide SIO2 layer located on the silicon substrate layer; A silicon waveguide, located on the substrate layer, the silicon waveguide comprising a first silicon waveguide portion and a second silicon waveguide portion, the first silicon waveguide portion and the second silicon waveguide portion are arranged along a preset direction, and the first silicon waveguide portion and the second silicon waveguide portion are spaced a preset distance apart; A semiconductor optical amplifier, wherein a base at the bottom is provided with a slot structure of a preset height in the length direction, so that the semiconductor optical amplifier is buckled above the first silicon waveguide part, the second silicon waveguide part and the gap therebetween through the slot walls on both sides of the slot structure; the width of the slot is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide; the length direction is the direction of propagation of the optical signal in the silicon waveguide; A cover layer, located on the semiconductor optical amplifier, for integrating the SOA with the silicon waveguide and protecting the semiconductor optical amplifier from water and oxygen in the atmosphere; The spacing between the first silicon waveguide portion and the second silicon waveguide portion is 4-6 μm.

2. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 1, characterized in that: The thickness of the two groove walls of the slot is half of the width of the slot, the width of the slot is w-10w, and the height of the slot is h-10h; wherein w is the width of the silicon waveguide, and h is the height of the silicon waveguide.

3. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 1, characterized in that: The two ends of the semiconductor optical amplifier in the length direction are respectively provided with a first tapered gradual change structure and a second tapered gradual change structure.

4. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 3, characterized in that: The distance from the bottom of the first tapered gradual change structure to the top of the tip is 6 μm; the distance from the bottom of the second tapered gradual change structure to the top of the tip is 6 μm.

5. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 1, 2 or 3, characterized in that: A third tapered structure is provided at the end of the first silicon waveguide portion close to the second silicon waveguide portion, a fourth tapered structure is provided at the end of the second silicon waveguide portion close to the first silicon waveguide portion, and a tip portion of the third tapered structure is opposite to a tip portion of the fourth tapered structure.

6. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 5, characterized in that: The distance between the tip of the third tapered gradual change structure and the tip of the fourth tapered gradual change structure is no more than 0.5 μm.

7. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 6, characterized in that: The distance from the bottom of the third tapered gradual change structure to the top of the tip is 2.5 μm, and the distance from the bottom of the fourth tapered gradual change structure to the top of the tip is 2.5 μm.

8. The highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure according to claim 1, characterized in that: The shapes of the end portions of the card slot include a rectangle and a triangle.

9. A method for preparing a highly efficient coupled silicon-based heterogeneous integrated semiconductor optical amplifier structure, characterized in that: include: Providing a substrate layer, the substrate layer comprising a silicon substrate layer and a buried oxide SIO2 layer located on the silicon substrate layer; A silicon waveguide including a first silicon waveguide portion and a second silicon waveguide portion is prepared on the buried oxide SIO2 layer in the substrate layer; the first silicon waveguide portion and the second silicon waveguide portion are arranged along a preset direction, and a preset distance is spaced between the first silicon waveguide portion and the second silicon waveguide portion; A semiconductor optical amplifier is provided, wherein a slot structure with a preset height is provided on a bottom substrate of the semiconductor optical amplifier in a length direction, and the semiconductor optical amplifier is buckled above the first silicon waveguide part, the second silicon waveguide part and the gap therebetween through slot walls on both sides of the slot structure; the width of the slot is not less than the width of the silicon waveguide, and the height of the slot is not less than the thickness of the silicon waveguide; the length direction is the direction in which an optical signal propagates in the silicon waveguide; and the spacing between the first silicon waveguide part and the second silicon waveguide part is 4-6 μm; A covering layer is prepared on the semiconductor optical amplifier by adopting PECVD process, which is used for integrating SOA and silicon waveguide and protecting the semiconductor optical amplifier from water and oxygen in the atmosphere.

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