A fully silicon homotype doped germanium optical waveguide modulator

Abstract

This invention discloses an all-silicon isomorphically doped germanium optical waveguide modulator, belonging to the field of silicon-based optoelectronic device technology. The modulator includes a metal electrode, a silicon oxide upper cladding, a waveguide layer, and a silicon oxide lower cladding stacked sequentially along a first direction. The waveguide layer includes a germanium absorption layer and a thin silicon layer, with the germanium absorption layer located between the thin silicon layer and the silicon oxide upper cladding. An isomorphically doped region structure is provided within the thin silicon layer below the germanium absorption layer. A via structure is provided within the silicon oxide upper cladding, electrically connecting the metal electrode and the thin silicon layer. This invention, by employing a single type of carrier doping structure, namely P-I-P and N-I-N structures, instead of the traditional P-I-N junction, reduces device capacitance, increases modulation bandwidth, and selectively optimizes extinction ratio or insertion loss. Furthermore, the process is fully compatible with CMOS and easy to integrate.

Description

Technical Field

[0001] This invention relates to the field of silicon-based optoelectronic device technology, and more specifically to an all-silicon isomorphically doped germanium optical waveguide modulator. Background Technology

[0002] With the explosive growth of data communication capacity, the demand for high-speed, low-power, and low-cost optoelectronic devices in optical interconnect systems is becoming increasingly urgent. Silicon-based photonics has become the mainstream technology in the field of optoelectronic integration due to its high compatibility with complementary metal-oxide-semiconductor (CMOS) processes, low optical transmission loss in communication bands (O-band to C-band), and high refractive index which is conducive to device miniaturization.

[0003] Optical waveguide modulators are core active devices in optical transmission links, and their performance directly determines signal quality. The modulation bandwidth of existing germanium-silicon optical waveguide modulators is mainly limited by the resistor-capacitor (RC) time constant.

[0004] To reduce the RC constant and improve bandwidth, traditional technologies often require more complex device structures (such as introducing additional doped regions or special electrode layouts) or more demanding process steps, which significantly increases manufacturing costs and process complexity. How to effectively reduce the equivalent capacitance of the modulator, improve bandwidth, and simultaneously maintain key performance indicators such as extinction ratio and insertion loss without significantly increasing process complexity is a pressing technical challenge in this field. Summary of the Invention

[0005] This invention addresses the technical shortcomings of existing germanium optical waveguide modulators, which have to increase structural complexity or manufacturing difficulty in order to reduce the RC time constant. It provides an all-silicon homo-doped germanium optical waveguide modulator, which aims to reduce device capacitance and increase modulation bandwidth without increasing manufacturing difficulty, and can selectively optimize extinction ratio or insertion loss according to application requirements.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An all-silicon isomorphically doped germanium optical waveguide modulator includes: metal electrodes, an upper silicon oxide cladding, a waveguide layer, and a lower silicon oxide cladding stacked sequentially along a first direction;

[0008] The waveguide layer includes a germanium absorption layer and a thin silicon layer, wherein the germanium absorption layer is located between the thin silicon layer and the silicon oxide cladding;

[0009] The thin silicon layer beneath the germanium absorber layer contains a homogeneous doped region structure.

[0010] The silicon oxide cladding has a through-hole structure, which electrically connects the metal electrode to the thin silicon layer.

[0011] Furthermore, the thin silicon layer is provided with a first isomorphic doped region and a second isomorphic doped region, and the first isomorphic doped region and the second isomorphic doped region are separated by an intrinsic silicon region.

[0012] Furthermore, both the first and second isomorphic doped regions are N-type doped regions, forming an NIN structure; or, both the first and second isomorphic doped regions are P-type doped regions, forming a PIP structure.

[0013] Furthermore, along the first direction, the lower surface of the germanium absorber layer overlaps with the intrinsic region located between the first isomorphic doped region and the second isomorphic doped region by a vertical projection; and each of the first isomorphic doped region and the second isomorphic doped region has a portion that overlaps with the lower surface of the germanium absorber layer by a vertical projection.

[0014] Furthermore, the optical signal is injected from the thin silicon layer region beneath the germanium absorption layer via waveguide coupling.

[0015] Furthermore, the via structure includes a first via and a second via respectively connecting the metal electrode to the first homogeneous doped region and the second homogeneous doped region; the metal electrode connected to the first homogeneous doped region is an N electrode, and the metal electrode connected to the second homogeneous doped region is a P electrode; the P electrode is used to apply a reverse bias voltage, and the N electrode is used to ground.

[0016] Furthermore, the thin silicon layer also includes a silicon waveguide structure formed by etching; one end of the silicon waveguide structure is connected to a grating coupler or an end-face coupler along the light propagation direction, and the other end is connected to the same-type doped region structure and the germanium absorption layer.

[0017] Furthermore, it also includes a silicon substrate layer disposed below the silicon oxide undercoat.

[0018] Furthermore, the germanium absorber layer is grown and prepared using a low-temperature buffer layer technique.

[0019] Compared with the prior art, the present invention provides an all-silicon isomorphically doped germanium optical waveguide modulator, which has the following beneficial effects:

[0020] 1. This invention implements only a single type of doping (all N-type or all P-type) within the thin silicon layer. Compared with the traditional lateral PIN structure that requires two different types of doping, it significantly simplifies the doping process steps, is fully compatible with standard CMOS processes, and reduces manufacturing costs and process control difficulty.

[0021] 2. Capacitance Reduction and Bandwidth Improvement of this Invention: This invention employs a homo-doped structure, avoiding the formation of large-area depletion layer capacitance in traditional PIN junctions. The device's equivalent capacitance is mainly dominated by geometric capacitance, significantly reducing the total capacitance and thus weakening the limitation of the RC time constant on the modulation bandwidth. Experimental results show that the 3dB bandwidth is improved to 1.17-1.45 times that of the traditional structure.

[0022] 3. When using PIP-type homo-doping, the change in electric field within the germanium absorption region caused by the applied reverse bias is significantly greater than that of the traditional PIN structure, resulting in enhanced electro-absorption effect. Measured extinction is improved by approximately 16.7% compared to the traditional structure. When using NIN-type homo-doping, the built-in electric field within the germanium absorption region is extremely small (close to zero) under zero bias, effectively reducing insertion loss. Measured insertion loss is approximately 7.2% lower than the traditional structure. Simultaneously, N-type doping makes it easier to achieve low-resistance ohmic contacts, further reducing contact resistance and benefiting high-frequency applications.

[0023] In summary, this invention comprehensively improves the core performance of the modulator, such as capacitance, bandwidth, extinction ratio, and insertion loss, without increasing the difficulty of the manufacturing process, and has significant novelty, inventiveness, and practicality. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0025] Figure 1(a) is a three-dimensional structural schematic diagram of the all-silicon isomorphically doped germanium optical waveguide modulator provided in an embodiment of the present invention;

[0026] Figure 1(b) is a schematic diagram of the cross-sectional structure of the all-silicon isomorphically doped germanium optical waveguide modulator provided in the embodiment of the present invention along the direction perpendicular to the light propagation.

[0027] Figure 2 This is a simulation diagram of the optical field distribution in the germanium absorption region provided in an embodiment of the present invention;

[0028] Figure 3(a) is a comparison of the electric field distribution of the embodiments of the present invention (PIP, NIN) and the traditional PIN structure under 0V bias.

[0029] Figure 3(b) is a comparison of the electric field distribution of the embodiment of the present invention and the traditional PIN structure under a -3V bias voltage;

[0030] Figure 4 This is a comparison diagram of the capacitance-voltage characteristics of the embodiments of the present invention and the traditional PIN structure;

[0031] Figure 5This is a comparison chart of the 3dB bandwidth response of the embodiment of the present invention and the traditional PIN structure.

[0032] The meanings of the markings in the attached diagram are as follows:

[0033] 01: Silicon substrate; 02: Lower silicon oxide cladding; 03: Thin silicon layer; 03a: First isomorphous doped region; 03c: Second isomorphous doped region; 03d: Silicon waveguide structure; 04: Germanium absorption layer; 05: Upper silicon oxide cladding; 06: Metal electrode; 06a: Through-hole structure. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] This application provides an all-silicon isomorphically doped germanium optical waveguide modulator, aiming to solve the technical problem of poor overall performance of existing germanium optical waveguide modulators without increasing process complexity. The two isomorphically doped structures provided by this invention, namely PIP-type and NIN-type germanium optical waveguide modulators, can effectively reduce device capacitance and increase modulator bandwidth. Specifically, the PIP-type structure can further improve the extinction ratio of the modulator, while the NIN-type structure can further reduce the insertion loss and contact resistance of the modulator.

[0036] The technical solution in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0037] In this invention, a metal electrode 06, a silicon oxide upper cladding layer 05, a waveguide layer, and a silicon oxide lower cladding layer 02 are stacked sequentially along a first direction. The waveguide layer includes a germanium absorption layer 04 and a thin silicon layer 03, with the germanium absorption layer 04 located between the thin silicon layer 03 and the silicon oxide upper cladding layer 05. The thin silicon layer 03 below the germanium absorption layer 04 has a homogeneous doped region structure. The silicon oxide upper cladding layer 05 includes a via structure 06a, which connects the metal electrode 06 and the thin silicon layer 03. Through this structure, this invention achieves both a reduction in device capacitance and an increase in modulator bandwidth without increasing process complexity. Specifically, the PIP-type structure can further improve the extinction ratio of the modulator, and the NIN-type structure can further reduce the insertion loss and resistance of the modulator, thereby significantly improving the overall performance of the modulator.

[0038] like Figure 1a and Figure 1bAs shown, this embodiment of the invention provides an all-silicon isomorphically doped germanium optical waveguide modulator. The modulator includes: a metal electrode 06, a silicon oxide upper cladding layer 05, a waveguide layer, a silicon oxide lower cladding layer 02, and a silicon substrate layer 01, stacked sequentially along a first direction, i.e., the vertical direction. The silicon substrate layer 01 is located below the silicon oxide lower cladding layer 02.

[0039] The waveguide layer includes a germanium absorber layer 04 and a thin silicon layer 03. The germanium absorber layer 04 is located between the thin silicon layer 03 and the silicon oxide cladding layer 05. Specifically, the germanium absorber layer 04 can be epitaxially grown on the upper surface of the thin silicon layer 03 or embedded within the thin silicon layer 03. An embedded structure means that before epitaxially growing the germanium absorber layer 04, the thin silicon layer 03 is first etched to a certain depth using an etching process, and then the germanium absorber layer 04 is epitaxially grown inside and outside the etched groove. Therefore, as... Figure 1b As shown, a portion of the germanium absorber layer 04 is embedded within the thin silicon layer 03, while another portion protrudes and sits atop the thin silicon layer 03. Optionally, the germanium absorber layer 04 is grown using a low-temperature buffer layer technique.

[0040] A homogeneous doped region structure is formed within the thin silicon layer 03 located beneath the germanium absorber layer 04. For example... Figure 1b As shown, the isomorphic doped region structure includes two symmetrically arranged isomorphic doped regions, namely the first isomorphic doped region 03a and the second isomorphic doped region 03c. The first isomorphic doped region 03a and the second isomorphic doped region 03c are separated by an undoped region, i.e., the intrinsic region. Isomorphic doping regions refer to the fact that both the first isomorphic doped region 03a and the second isomorphic doped region 03c are either N-type doped or both are P-type doped.

[0041] Furthermore, along the first direction, i.e., the vertical direction, the lower surface of the germanium absorber layer 04 vertically overlaps with the intrinsic region located between the first isomorphic doped region 03a and the second isomorphic doped region 03c. Also, a portion of each of the first isomorphic doped region 03a and the second isomorphic doped region 03c vertically overlaps with the lower surface of the germanium absorber layer 04. The width of the isomorphic doped region structure perpendicular to the first direction along the second direction, i.e., the horizontal direction, is smaller than the width of the germanium absorber layer 04 minus the width of the overlapping area between the germanium absorber layer 04 and the two isomorphic doped regions 03a and 03c.

[0042] A via structure 06a is provided within the silicon oxide cladding 05. The via structure 06a electrically connects the metal electrode 06 and the thin silicon layer 03. Specifically, the via structure 06a includes vias connecting the metal electrode 06 to a first homomorphic doped region 03a and a second homomorphic doped region 03c, respectively, with ohmic contact between the metal and semiconductor components. The metal electrode connected to the first homomorphic doped region 03a is an N-electrode, and the metal electrode connected to the second homomorphic doped region 03c is a P-electrode. During operation, the P-electrode is used to apply a reverse bias voltage, and the N-electrode is used for grounding.

[0043] In this embodiment of the invention, the thin silicon layer 03 further includes a silicon waveguide structure 03d formed by etching. One end of the silicon waveguide structure 03d is connected to a grating coupler or an end-face coupler along the light propagation direction perpendicular to the plane defined by the first and second directions; the other end is connected to the same-type doped region structure and the germanium absorption layer 04, and serves as the epitaxial region of germanium through an etched window.

[0044] During operation, optical signals in the communication band enter the silicon waveguide structure 03d through a coupler. At the other end of the silicon waveguide structure 03d, part of the optical signal directly enters the germanium absorption layer 04 and is absorbed, while the other part enters the remaining thin silicon layer region located below the germanium absorption layer 04. By changing the applied bias voltage, the strength of the light absorption effect within the germanium absorption layer 04 is altered, thereby achieving modulation of the optical signal.

[0045] To further illustrate the technical solution and beneficial effects of the present invention, two types of all-silicon isomorphically doped germanium optical waveguide modulators are selected as specific embodiments, namely Embodiment 1 (PIP type) and Embodiment 2 (NIN type). Meanwhile, a traditional PIN structure modulator is used for comparison. Specific parameters for each embodiment and the comparative structure are shown in Table 1.

[0046] Table 1 Key parameters of the embodiments and comparative structures

[0047] Silicon substrate thickness (μm) 725 725 725 Thickness of cladding layer under silicon oxidation (μm) 2 2 2 Thin silicon layer thickness (nm) 220 220 220 Germanium absorber layer thickness / width (nm) 300 / 600 300 / 600 300 / 600 Thickness of the silicon oxide cladding layer (μm) 1.1 1.1 1.1 Width of the isomorphic doped region - 03a (μm) 2 2 2 Width of the homotype doped region 2 O3c (μm) 2 2 2

[0048] Example 1 (PIP type structure)

[0049] This embodiment provides an all-silicon isomorphically doped germanium optical waveguide modulator, the basic structure of which is as described above. The first isomorphically doped region 03a and the second isomorphically doped region 03c are both P-type doped, forming a PIP structure. Each isomorphically doped region includes a heavily doped region with a width of 2 μm and a lightly doped region with a width of 700 nm. An ohmic contact is formed between the metal electrode 06 and the P-type doped region. The metal electrode connected to the first isomorphically doped region 03a is a P-electrode, and the metal electrode connected to the second isomorphically doped region 03c is an N-electrode. During operation, a reverse bias voltage, for example -3V, is applied to the P-electrode, and the N-electrode is grounded. Other structural parameters, such as the thickness of the thin silicon layer, the size of the germanium absorber layer, and the cladding thickness, are consistent with those in Embodiment 1 in Table 1.

[0050] Example 2 (NIN type structure)

[0051] The difference between this embodiment and Embodiment 1 is that both the first isotype doped region 03a and the second isotype doped region 03c are N-type doped, forming an NIN structure. An ohmic contact is formed between the metal electrode 06 and the N-type doped region. The remaining structure and parameters are the same as in Embodiment 1; please refer to the parameters of Embodiment 2 in Table 1 for details.

[0052] The extinction ratio, insertion loss, and modulation bandwidth of the conventional PIN structure modulator, the modulator of Example 1 (PIP type), and the modulator of Example 2 (NIN type) were tested respectively. The test environment was room temperature.

[0053] The extinction ratio and insertion loss were tested as follows: A 1600nm continuous light source was used, coupled into a grating coupler via optical fiber, and the optical signal was injected into the modulator. The input optical power was 7dBm, and the grating coupler loss was approximately 4.45dB. Based on this, the actual optical power entering the active region of the modulator was calculated to be approximately 2.55dBm. By adjusting the applied bias voltage, the change in output optical power was recorded, thereby extracting the insertion loss and extinction ratio of the device.

[0054] The modulator bandwidth test method is as follows: Based on a vector network analyzer, a small signal RF voltage is applied to the device using a high-frequency probe, while the modulation response of the output optical signal is monitored. The optical signal is converted into an electrical signal by a photodetector and input into the vector network analyzer to obtain the device's electro-optical transfer function S21, and then its 3dB modulation bandwidth is extracted.

[0055] Figure 2 The optical field distribution of the absorption region of the germanium waveguide structure of the present invention is shown. As can be seen from the figure, the optical field is strongest at the center of the germanium waveguide and gradually weakens towards the edge. The intensity of absorption of the optical signal varies in the germanium waveguide region with changes in the applied bias voltage, thus producing a modulation effect. To improve the modulation effect of the device, the high optical field intensity region needs to coincide with the high electric field region as much as possible. The traditional approach to enhancing the electric field intensity in the germanium waveguide region is along... Figure 2 Doping is performed on both sides of the germanium region in the horizontal direction, but this increases the manufacturing difficulty and the absorption loss of the germanium waveguide. The modulator structure proposed in this embodiment of the invention can enhance the electric field strength of the germanium waveguide absorption region without increasing the doping in the germanium absorption region, thereby improving the overall performance of the modulator.

[0056] Figure 3a and Figure 3b Simulation comparisons of electric field distributions for the traditional PIN structure, Example 1 (PIP type), and Example 2 (NIN type) are shown under bias voltages of 0V and -3V, respectively.

[0057] from Figure 3a and Figure 3b It can be seen that when the applied bias voltage changes from 0V to -3V, the electric field change amplitude of Example 1 (PIP type) is the largest, and the peak electric field is the highest. This indicates that the PIP structure has a greater advantage over the traditional structure in improving the modulation depth.

[0058] from Figure 3aIt can be seen that under 0V bias, the traditional PIN structure exhibits a significant built-in electric field in the germanium region, which is a major reason for its high insertion loss. In contrast, the electric field in Example 2 (NIN type) is antisymmetric in the germanium region, with the electric field strength at the center of its absorption region approaching zero, thus effectively reducing insertion loss.

[0059] Figure 4 The results show the capacitance measurements of the conventional structure, the modulators of Example 1 and Example 2, fabricated on the same wafer. Experimental data indicates that the capacitance of the embodiments of the present invention is significantly reduced compared to the conventional structure. Specifically, the capacitance of Example 1 is reduced by 22.4% compared to the conventional structure, and the capacitance of Example 2 is reduced by 22.9%. Furthermore, the resistance of the conventional structure and the embodiments was tested. Experimental data shows that the resistance of Example 1 is increased by 10.6% compared to the conventional structure, while the resistance of Example 2 is reduced by 10.7% compared to the conventional structure.

[0060] In the homo-doped structures (Examples 1 and 2), the lack of a strong built-in electric field provided by the PN junction results in a relatively weak and uneven electric field distribution, leading to a significant increase in capacitance in the low-bias region. At this point, the capacitance is primarily diffusion capacitance. As a large number of charge carriers are injected, they accumulate at the edge of the barrier region, gradually reducing the diffusion capacitance and transitioning to a mechanism dominated by barrier capacitance. At this stage, the weaker charge carrier storage capacity of the homo-doped structure causes a rapid decrease in capacitance. In contrast, the traditional PIN structure possesses a significant built-in electric field within the PN junction, which rapidly sweeps charge carriers out of the active region under reverse bias. This allows the device capacitance to be primarily controlled by the depletion layer, exhibiting a monotonically decreasing characteristic with increasing reverse bias voltage, although the rate of decrease is relatively slower compared to homo-doped structures.

[0061] Figure 5 The conventional structure modulators, Example 1 and Example 2, fabricated on the same wafer, are shown, with 3dB bandwidth data measured at -1V and -2V.

[0062] Experimental data shows that, under a -1V bias, the 3dB bandwidth of the modulator in this embodiment is approximately 1.15 times that of the conventional modulator; under a -2V bias, the 3dB bandwidth of the modulator in this embodiment is approximately 1.17 times that of the conventional modulator. Specifically, the 3dB bandwidth of the modulator in Embodiment 1 is approximately 1.17 times that of the conventional modulator, and the 3dB bandwidth of the modulator in Embodiment 2 is approximately 1.45 times that of the conventional modulator. The increased bandwidth is due to the fact that the isomorphic doped structure used in this invention alters the capacitance and resistance of the device, thereby reducing the limitation of the RC time constant on the bandwidth and ultimately improving the 3dB bandwidth.

[0063] The modulator of Example 1 (PIP type) was tested, and the results showed that its extinction ratio was 5.17dB, which is about 16.7% higher than that of the traditional PIN structure (4.43dB); its insertion loss was 4.51dB, which is about 7.6% higher than that of the traditional PIN structure (4.19dB). It can be seen that the PIP type structure significantly improves the extinction ratio while sacrificing a small amount of insertion loss.

[0064] The modulator of Example 2 (NIN type) was tested, and the results showed that its insertion loss was 3.89 dB, which was about 7.2% lower than that of the traditional PIN structure (4.19 dB); its extinction ratio was 1.19 dB, which was lower than that of the traditional PIN structure. It is evident that the NIN type structure effectively reduces insertion loss by sacrificing some extinction ratio. Furthermore, N-type doping makes it easier to achieve low-resistance ohmic contacts, which is beneficial for high-frequency applications.

[0065] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0066] First, it requires no additional process steps, is easy to manufacture, and is perfectly compatible with CMOS processes. This invention implements only a single type of doping, either all N-type or all P-type, within a thin silicon layer. Compared to traditional lateral PIN structures that require two different types of doping, it significantly simplifies the doping process, reduces manufacturing costs, and lowers the difficulty of process control.

[0067] Second, the isomorphic doping structure effectively reduces capacitance, thereby reducing the limitation of the RC time constant on the modulator bandwidth and increasing the modulator bandwidth. Simultaneously, this structure allows carrier transport to occur primarily in single-crystal germanium material with higher mobility, which is also a favorable factor for increasing device bandwidth. Experimental results show that, at a -2V bias, the 3dB bandwidth of this embodiment is increased to 1.17 times that of the conventional structure.

[0068] Third, the PIP-type structure in isomorphic doping can increase the amplitude of the electric field change in the germanium absorption region when the reverse bias changes from 0V to -3V, enhancing the electro-absorption effect and thus improving the extinction ratio of the modulator. The measured extinction ratio is approximately 16.7% higher than that of the traditional structure.

[0069] IV. The NIN-type structure in isotype doping can reduce the electric field in the germanium absorption region under 0V bias, weaken the electroabsorption effect, thereby reducing insertion loss and improving device modulation efficiency. Measured insertion loss is approximately 7.2% lower than the traditional structure. Simultaneously, N-type doping makes it easier to achieve low-resistance ohmic contacts, further reducing contact resistance and benefiting high-frequency applications.

[0070] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A silicon-based isomorphically doped germanium optical waveguide modulator, characterized in that, include: Metal electrode (06), silicon oxide upper cladding (05), waveguide layer and silicon oxide lower cladding (02) are stacked sequentially along the first direction. The waveguide layer includes a germanium absorption layer (04) and a thin silicon layer (03), wherein the germanium absorption layer (04) is located between the thin silicon layer (03) and the silicon oxide cladding (05); The thin silicon layer (03) below the germanium absorber layer (04) has a homogeneous doped region structure; The silicon oxide cladding (05) has a through-hole structure (06a) which electrically connects the metal electrode (06) and the thin silicon layer (03).

2. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 1, characterized in that, The thin silicon layer (03) has a first isomorphic doped region (03a) and a second isomorphic doped region (03c), and the first isomorphic doped region (03a) and the second isomorphic doped region (03c) are separated by an intrinsic silicon region.

3. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 2, characterized in that, The first isomorphic doped region (03a) and the second isomorphic doped region (03c) are both N-type doped regions, forming an NIN structure; or, the first isomorphic doped region (03a) and the second isomorphic doped region (03c) are both P-type doped regions, forming a PIP structure.

4. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 2, characterized in that, Along the first direction, the lower surface of the germanium absorption layer (04) overlaps with the intrinsic region located between the first isomorphic doped region (03a) and the second isomorphic doped region (03c) by a vertical projection; and each of the first isomorphic doped region (03a) and the second isomorphic doped region (03c) has a portion that overlaps with the lower surface of the germanium absorption layer (04) by a vertical projection.

5. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 1, characterized in that, Optical signals are injected from the region of the thin silicon layer (03) below the germanium absorption layer (04) via waveguide coupling.

6. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 2, characterized in that, The through-hole structure (06a) includes a first through-hole and a second through-hole respectively connecting the metal electrode (06) with the first isomorphic doped region (03a) and the second isomorphic doped region (03c); The metal electrode connected to the first homogeneous doped region (03a) is an N electrode, and the metal electrode connected to the second homogeneous doped region (03c) is a P electrode; the P electrode is used to apply a reverse bias voltage, and the N electrode is used to ground.

7. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 2, characterized in that, The thin silicon layer (03) also includes a silicon waveguide structure (03d) formed by etching; one end of the silicon waveguide structure (03d) is connected to a grating coupler or an end-face coupler along the light propagation direction, and the other end is connected to the same type doped region structure and the germanium absorption layer (04).

8. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 1, characterized in that, It also includes a silicon substrate layer (01) disposed below the silicon oxide undercoat layer (02).

9. The all-silicon isomorphically doped germanium optical waveguide modulator according to claim 1, characterized in that, The germanium absorber layer (04) is prepared by low-temperature buffer layer technology.

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