Microdisk modulator

Abstract

A micro-disk modulator provided by an embodiment of the present invention comprises: a substrate layer; a planar waveguide layer located on the substrate layer; a coupling waveguide and a micro-disk resonance structure arranged in parallel in the planar waveguide layer, the micro-disk resonance structure comprising a first doping structure and a second doping structure stacked in sequence along the thickness direction of the substrate layer, the first doping structure and the second doping structure have opposite doping types, the projection of the second doping structure on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer; and an electrode electrically connected to the micro-disk resonance structure.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a micro-disk modulator. Background Art

[0002] Drawing on the development path of large-scale integrated circuits, research is being conducted at home and abroad to integrate active devices (such as modulators, detectors, etc.) and optical waveguide devices (such as splitters / combiners, etc.) onto a substrate to achieve photonic integrated chips with similar advantages to large-scale integrated circuits. Photonic integrated chips have the characteristics of low cost, small size, low power consumption, flexible expansion and high reliability. In the process of optical fiber communication, the intensity of light can be controlled by electro-optic modulators. Therefore, electro-optic modulators occupy an important position in optical fiber communication systems. At the same time, electro-optic modulators are also one of the important optoelectronic devices in photonic integrated chip solutions.

[0003] In recent years, silicon-based electro-optic modulators are an important research direction in electro-optic modulators, and they play a vital role in optical cross-connect (OXC) and optical differential multiplexing (OADM) in the field of optical communications. There are two main types of silicon-based electro-optic modulators: one is the electro-refractive index electro-optic modulator, which realizes the change from phase to intensity through an interferometer or resonant device, and finally realizes the modulation of optical signals; the other is the electro-absorption electro-optic modulator, which changes the imaginary part of the refractive index through an external electric field, thereby directly changing the intensity change of the light wave in the electro-optic modulator, and finally realizes the modulation of optical signals.

[0004] At present, a variety of silicon-based electro-optic modulators have been successfully designed and manufactured, and various technical indicators have been gradually improved. However, the comprehensive performance is still far behind the mature lithium niobate electro-optic modulator, and it cannot meet the future development requirements of optical interconnection and optical communication. Specifically, since the photoelectric effect of silicon material itself is very weak compared with other materials, the change of the applied electric field makes the change of the refractive index of silicon material relatively small. In order to overcome this shortcoming, it is necessary to increase the size of the electro-optic modulator to achieve a better modulation effect. In order to achieve small-size integration, scientific researchers have studied many novel structures, among which the micro-disk modulator is a structure with a more obvious effect. In the related technology, it is necessary to reduce the size of the micro-disk modulator while further improving the modulation efficiency of the micro-disk modulator, thereby improving the integration of the photonic integrated chip and reducing the preparation cost. Summary of the invention

[0005] In view of this, an embodiment of the present invention is intended to provide a micro-disk modulator.

[0006] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] The microdisk modulator comprises:

[0008] substrate layer;

[0009] a planar waveguide layer located on the substrate layer;

[0010] A coupled waveguide and a micro-disk resonant structure are arranged in parallel in the planar waveguide layer, wherein the micro-disk resonant structure comprises a first doping structure and a second doping structure which are sequentially stacked along the thickness direction of the substrate layer, wherein the first doping structure and the second doping structure have opposite doping types, and the projection of the second doping structure on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer; and

[0011] An electrode is electrically connected to the micro-disk resonant structure.

[0012] In the above scheme, the first doping structure includes a first doping region and a second doping region of the same doping type as the first doping region and at least partially surrounding the first doping region; the second doping structure includes a third doping region and a fourth doping region of the same doping type as the third doping region and surrounding the third doping region; wherein the first doping structure and the second doping structure are physically connected to the fourth doping region through the first doping region; and the second doping region has no physical contact with the third doping region.

[0013] In the above solution, the projection of the first doping structure on the preset plane is a fan-shaped ring.

[0014] In the above solution, the first doping region and the second doping region include N-type doping, and the third doping region and the fourth doping region include P-type doping.

[0015] In the above solution, the top surface of the coupling waveguide is flush with the top surface of the second doping structure; the first doping structure is located in the slab waveguide layer and the top surface of the first doping structure is flush with the top surface of the slab waveguide layer.

[0016] In the above solution, the electrode includes a first electrode and a second electrode; wherein the first electrode is located in the second doping region, and the second electrode is located in the third doping region.

[0017] In the above scheme, the projection of the coupled waveguide on the preset plane is a long strip; the projections of the first doped region and the second doped region on the preset plane are both fan-shaped, the projection of the third doped region on the preset plane is a circle, and the projection of the fourth doped region on the preset plane is a ring.

[0018] In the above solution, the diameter width of the physical contact point between the first doping region and the fourth doping region ranges from 300 nanometers to 600 nanometers.

[0019] In the above solution, the micro-disk modulator further comprises a covering layer covering the slab waveguide layer, the coupling waveguide and the micro-disk resonant structure, and the refractive index of the covering layer is smaller than the refractive index of the slab waveguide layer.

[0020] In the above solution, the material of the substrate layer includes silicon dioxide; the material of the planar waveguide layer includes single crystal silicon; the material of the first doping structure includes single crystal silicon; and the material of the second doping structure includes single crystal silicon.

[0021] The micro-disk modulator provided by the embodiment of the present invention comprises: a substrate layer; a planar waveguide layer located on the substrate layer; a coupling waveguide and a micro-disk resonant structure arranged in parallel in the planar waveguide layer, wherein the micro-disk resonant structure comprises a first doping structure and a second doping structure sequentially stacked in the thickness direction of the substrate layer, wherein the first doping structure and the second doping structure have opposite doping types, and the projection of the second doping structure on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer; and an electrode electrically connected to the micro-disk resonant structure. In the embodiment of the present invention, a vertical PN junction electrical modulation structure is formed at the junction of the first doping structure and the second doping structure by sequentially stacking the first doping structure and the second doping structure in the thickness direction of the substrate layer, and the vertical PN junction electrical modulation structure can increase the overlapping area between the PN junction depletion region and the light wave mode field, improve the interaction between the light wave and the carrier, and thus improve the modulation efficiency; at the same time, the vertical PN junction electrical modulation structure can reduce the size occupied by the modulation structure, thereby reducing the size of the micro-disk modulator, thereby improving the integration of the photonic integrated chip and reducing the preparation cost. In addition, compared with a micro-ring modulator with a vertical PN junction, a micro-disk modulator has a simple structure and does not require the formation of a polysilicon micro-ring on a silicon material after forming a single-crystal silicon micro-ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A cross-sectional schematic diagram of a micro-disk modulator provided by an embodiment of the present invention;

[0023] Figure 2 for Figure 1 Schematic diagram of the cross section along the AA direction;

[0024] Figure 3 for Figure 1 Schematic diagram of the cross section along the BB direction. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] In the description of the present invention, it is necessary to understand that the terms "length", "width", "depth", "up", "down", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In the embodiments of the present invention, the term "substrate" refers to the material on which subsequent material layers are added. The substrate itself can be patterned. The material added on top of the substrate can be patterned or can remain unpatterned. In addition, the substrate can include a variety of semiconductor materials, such as silicon, germanium, gallium arsenide, indium phosphide, etc. Alternatively, the substrate can be made of non-conductive materials, such as glass, plastic, or sapphire wafers.

[0028] In an embodiment of the present invention, the term "layer" refers to a material portion including an area with a thickness. The layer may extend over the entirety of the lower or upper structure, or may have a range that is smaller than the range of the lower or upper structure. In addition, the layer may be a region of a homogeneous or inhomogeneous continuous structure having a thickness that is less than the thickness of the continuous structure. For example, the layer may be located between the top surface and the bottom surface of the continuous structure, or the layer may be between any horizontal faces at the top surface and the bottom surface of the continuous structure. The layer may extend horizontally, vertically and / or along an inclined surface. The layer may include multiple sublayers. For example, an interconnect layer may include one or more conductors and contact sublayers (where interconnects and / or via contacts are formed), and one or more dielectric sublayers.

[0029] In the embodiments of the present invention, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0030] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0031] In optical communication systems, electro-optic modulators are a key component. Currently, there are generally three types of commercial electro-optic modulators: electro-optic modulators based on lithium niobate, electro-optic modulators based on III-V materials, and silicon-based electro-optic modulators. However, the modulation efficiency of traditional lithium niobate modulators is low and the modulator size is large; the production cost of electro-optic modulators based on III-V materials is very high. Silicon-based modulators are compatible with the currently mature complementary metal oxide semiconductor (CMOS) process, so they can be processed and prepared on a large scale, reducing the production cost of electro-optic modulators.

[0032] Due to the centrosymmetric structure of silicon materials, there is no Pockels effect, and the Kerr effect and Franz-Keldish effect of silicon materials are also extremely weak; even if 10 5 The electric field of V / cm produces a refractive index change of less than 10 -5 , it is not realistic to use the Kerr effect and Franz-Keldish effect to achieve electro-optic modulation. Therefore, in silicon materials, the most effective electro-optic effect is the plasma dispersion effect. This effect can be expressed as: the refractive index of the material decreases with the increase of the carrier concentration in the material, and the absorption coefficient of the material to the light field increases with the increase of the carrier concentration. By using this effect, the carrier concentration in the silicon waveguide can be changed by applying an external voltage signal, and the transmission characteristics of light in the waveguide can be changed. Then, through a certain optical structure, such as a micro-disk resonant cavity, the purpose of electro-optic modulation can be achieved. Since the plasma dispersion effect is quite significant in electro-optic modulators, silicon-based electro-optic modulators are currently mainly realized through the plasma dispersion effect of free carriers in silicon materials.

[0033] In the related art, considering that the modulation efficiency of the plasma dispersion effect modulator is very low, in order to achieve the ideal modulation depth, the modulator needs to be designed to be very long, generally several millimeters in length, which results in a large size of the modulator, making it difficult to further improve the integration, thereby increasing the preparation cost. The use of resonant structures such as micro-ring resonators, micro-disk resonators or photonic crystal resonators can greatly reduce the size of the modulator. Modulators based on micro-rings and micro-disks have the advantages of small size, high sensitivity and easy integration, and have always attracted the attention of researchers in the industry. Usually, a micro-ring modulator includes a micro-ring resonator composed of a ring waveguide; a micro-disk modulator includes a disk-shaped resonator.

[0034] In the related art, the micro-disk modulator generally includes a P-type doped region and an N-type doped region arranged in parallel along the horizontal direction (parallel to the surface of the substrate layer), and the P-type doped region and the N-type doped region constitute a lateral PN junction. Since the lateral PN junction is easier to prepare, the micro-disk modulator generally adopts a lateral PN junction. However, the interaction between the lateral PN junction and the light field is small, which will lead to a low modulation efficiency of the micro-disk modulator, thereby affecting the size of the micro-disk modulator.

[0035] Based on this, an embodiment of the present invention aims to provide an ultra-small micro-disk modulator. In the embodiment of the present invention, a first doping structure and a second doping structure are stacked in sequence along the thickness direction of the substrate layer, and a vertical (perpendicular to the surface of the substrate layer) PN junction electrical modulation structure is formed at the junction of the first doping structure and the second doping structure. The vertical PN junction electrical modulation structure can increase the overlapping area between the PN junction depletion region and the light wave mode field, improve the interaction between the light wave and the carrier, and thus improve the modulation efficiency; at the same time, the vertical PN junction electrical modulation structure can reduce the size occupied by the modulation structure, thereby reducing the size of the micro-disk modulator, thereby improving the integration of the photonic integrated chip and reducing the preparation cost. In addition, compared with a micro-ring modulator with a vertical PN junction, the micro-disk modulator has a simple structure and does not need to continue to form a polycrystalline silicon micro-ring on the silicon material after forming a single-crystal silicon micro-ring.

[0036] An embodiment of the present invention provides a micro-disk modulator, comprising:

[0037] substrate layer;

[0038] a planar waveguide layer located on the substrate layer;

[0039] A coupled waveguide and a micro-disk resonant structure are arranged in parallel in the planar waveguide layer, wherein the micro-disk resonant structure comprises a first doping structure and a second doping structure which are sequentially stacked along the thickness direction of the substrate layer, wherein the first doping structure and the second doping structure have opposite doping types, and the projection of the second doping structure on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer; and

[0040] An electrode is electrically connected to the micro-disk resonant structure.

[0041] In practical applications, the working principle of the micro-disk resonant structure is generally as follows: under the action of the voltage transmitted by the electrode, the light input from one end of the coupling waveguide and coupled into the micro-disk resonant structure is modulated, and the modulated light is output from the other end of the coupling waveguide.

[0042] Figure 1 Schematic cross-sectional view of a micro-disk modulator provided by an embodiment of the present invention. Figure 1As shown, the micro-disk modulator includes: a substrate layer 10; a planar waveguide layer 20 located on the substrate layer 10; a coupling waveguide 30 and a micro-disk resonant structure 40 arranged in parallel in the planar waveguide layer 20, the micro-disk resonant structure 40 includes a first doping structure 41 and a second doping structure 42 stacked in sequence along the thickness direction of the substrate layer 10, the first doping structure 41 and the second doping structure 42 have opposite doping types, the projection of the second doping structure 42 on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer 10; and an electrode 50 electrically connected to the micro-disk resonant structure 40.

[0043] Here, the substrate layer 10 is used to support the planar waveguide layer 20 and confine light in the waveguide structure in the planar waveguide layer 20. In practical applications, the material of the substrate layer 10 may include but is not limited to silicon dioxide.

[0044] The material of the planar waveguide layer 20 may include but is not limited to single crystal silicon. It should be noted that the refractive index of the planar waveguide layer 20 for light is greater than that of the cladding material adjacent to the planar waveguide layer 20, thereby generating a waveguide effect. Here, the cladding material includes the substrate layer 10 and other materials adjacent to the planar waveguide layer 20.

[0045] The coupling waveguide 30 is used to receive incident light and output outgoing light. In practical applications, the material of the coupling waveguide 30 may include single crystal silicon. The projection of the coupling waveguide 30 on the preset plane includes a long strip, and the coupling waveguide 30 and the planar waveguide layer 20 constitute a strip ridge waveguide, so as to better limit the range of the optical wave mode field; here, the preset plane is perpendicular to the thickness direction of the substrate layer 10. It should be noted that in the embodiments of the present invention, the specific structure of the coupling waveguide 30 is not limited. Specifically, the coupling waveguide 30 of the micro-disk modulator in the embodiments of the present invention may include one of a strip ridge waveguide, a strip waveguide, an L-type waveguide, or other waveguide structures with equivalent effects.

[0046] The micro-disk resonant structure 40 includes a first doping structure 41 and a second doping structure 42 stacked in sequence along the thickness direction of the substrate layer 10. The first doping structure 41 and the second doping structure 42 have opposite doping types. The materials of the first doping structure 41 and the second doping structure 42 may include single crystal silicon.

[0047] Here, the micro-disk resonant structure 40 is used to modulate the light input from one end of the coupling waveguide 30 and coupled to the micro-disk resonant structure 40 under the action of the voltage transmitted by the electrode 50, and the modulated light is output from the other end of the coupling waveguide 30. Specifically, the doping type of the first doping structure 41 is opposite to that of the second doping structure 42, so that a vertical PN junction electrical modulation structure is formed at the physical junction of the first doping structure 41 and the second doping structure 42. According to the free carrier diffusion and drift effect in the PN junction, when a forward bias is applied to the PN junction in the micro-disk resonant structure 40, a current will be injected into the PN junction depletion region under the action of the external electric field, thereby causing a sharp increase in the free carrier concentration in the PN junction depletion region; when a reverse bias is applied to the PN junction in the micro-disk resonant structure 40, the free carriers distributed in the PN junction will be drawn away. At the same time, according to the plasma dispersion effect of silicon material, when the free carrier concentration in the silicon material changes, the refractive index of the silicon material will change. Therefore, the change of free carrier concentration in the PN junction will cause the refractive index of the waveguide material in the PN junction region to change. When an external voltage is applied to the micro-disk resonant structure 40, the free carrier concentration in the PN junction will change, thereby causing the refractive index of the silicon material to change, causing the wavelength of the optical signal transmitted in the optical waveguide to shift, thereby forming a modulation effect on the optical signal.

[0048] In practical applications, the projection of the second doping structure 42 on a preset plane is circular, and the projection of the first doping structure 41 on a preset plane is fan-shaped or ring-shaped. The preset plane is perpendicular to the thickness direction of the substrate layer 10 .

[0049] In practical applications, the coupling waveguide 30 is relatively close to the microdisk resonant structure 40 (usually a few hundred nanometers), and the light input at one end of the coupling waveguide 30 can be coupled to the microdisk resonant structure 40 in the form of an evanescent wave. That is to say, the optical wave mode field in the coupling waveguide 30 will be coupled with the waveguide in the microdisk resonant structure 40, and a part of the light will penetrate into the microdisk resonant cavity. When the light penetrating into the microdisk resonant cavity meets certain conditions, it can resonate in the microdisk resonant cavity and continuously strengthen due to the effect of positive feedback. At the same time, part of the light will also couple out of the microdisk and enter the coupling waveguide 30; if certain conditions are not met, the light in the microdisk resonant cavity will continue to weaken. The other part of the light that is not coupled into the microdisk resonant cavity will be output from the other end of the coupling waveguide 30. In practical applications, when the wavelength of the transmitted light meets a specific relationship with the microdisk radius, the effective refractive index of the transmitted light in the microdisk and other parameters, the light can resonate in the microdisk and continuously strengthen due to the effect of positive feedback.

[0050] In practical applications, an external voltage is applied to the micro-disk resonant structure 40 through the electrode 50 .

[0051] In practical applications, under the condition that the radius of the microring is the same as that of the microdisk, the modulation efficiency of the microdisk modulator is higher than that of the microring modulator. This is because, if the manufacturing process is the same, the microring resonant cavity has two sidewall surfaces, while the microdisk resonant cavity relatively has only one outer surface. In this way, for the microring modulator, the light scattering caused by the roughness of the sidewall surface caused by manufacturing is stronger, and the resulting light loss will be stronger, so the modulation efficiency of the microdisk modulator is higher. In addition, compared with the microring modulator with a vertical PN junction, the microdisk modulator has a simple structure and does not need to continue to form a polycrystalline silicon microring on the silicon material after forming a single-crystal silicon microring.

[0052] In the embodiment of the present invention, the micro-disk resonant structure 40 is specially designed, that is, by stacking the first doping structure 41 and the second doping structure 42 in sequence along the thickness direction of the substrate layer 10, a vertical PN junction electrical modulation structure is formed at the physical junction of the first doping structure 41 and the second doping structure 42. It can be understood that in the micro-disk resonant structure 40 provided by the present invention, the vertical PN junction electrical modulation structure can increase the overlapping area between the PN junction depletion region and the light wave mode field, improve the interaction between the light wave and the carrier, and thus improve the modulation efficiency; at the same time, the vertical PN junction electrical modulation structure can reduce the size occupied by the modulation structure, thereby reducing the size of the micro-disk modulator, thereby improving the integration of the photonic integrated chip and reducing the preparation cost. In addition, compared with the micro-ring modulator with a vertical PN junction, the micro-disk modulator has a simple structure and does not need to continue to form a polycrystalline silicon micro-ring on the silicon material after forming a single-crystal silicon micro-ring.

[0053] In one embodiment, the first doping structure 41 includes a first doping region 41A and a second doping region 41B having the same doping type as the first doping region 41A and at least partially surrounding the first doping region 41A; the second doping structure 42 includes a third doping region 42A and a fourth doping region 42B having the same doping type as the third doping region 42A and surrounding the third doping region 42A; wherein the first doping structure 41 and the second doping structure 42 are physically connected to the fourth doping region 42B via the first doping region 41A; and the second doping region 41B has no physical contact with the third doping region 42A.

[0054] In practical applications, the projections of the first doping region 41A and the second doping region 41B on the preset plane are fan-shaped or ring-shaped; the projection of the third doping region 42A on the preset plane is circular, and the projection of the fourth doping region 42B on the preset plane is a ring-shaped surrounding the first doping region 41A. Here, when the projections of the first doping region 41A and the second doping region 41B on the preset plane are fan-shaped, the second doping region 41B partially surrounds the first doping region 41A; when the projections of the first doping region 41A and the second doping region 41B on the preset plane are ring-shaped, the second doping region 41B completely surrounds the first doping region 41A.

[0055] In practical applications, the first doping region 41A is in direct contact with the second doping region 41B to form a first doping structure 41; the third doping region 42A is in direct contact with the fourth doping region 42B to form a second doping structure 42. The first doping structure 41 and the second doping structure 42 are physically connected to form a vertical PN junction through the first doping region 41A and the fourth doping region 42B; the change in the carrier concentration in the vertical PN junction causes the change in the refractive index of the waveguide material in the PN junction area. The first doping structure 41 and the second doping structure 42 constitute a micro-disk resonant cavity. The micro-disk resonant cavity can confine the light wave to a very small range, greatly reducing the size of the electro-optic modulator.

[0056] In practical applications, the first doping region 41A is a lightly doped region, and the second doping region 41B is a heavily doped region; the fourth doping region 42B is a lightly doped region, and the third doping region 42A is a heavily doped region. It can be understood that the doping concentration of the second doping region 41B is higher than the doping concentration of the first doping region 41A, and the doping concentration of the third doping region 42A is higher than the doping concentration of the fourth doping region 42B, thereby reducing the contact resistance between the electrode and the doping region, and further improving the efficiency of the micro-disk modulator.

[0057] In practical applications, the top surface of the coupling waveguide 30 is higher than the top surface of the slab waveguide layer 20. It can be understood that the top surface of the coupling waveguide 30 is higher than the top surface of the slab waveguide layer 20, so that the coupling waveguide 30 and the slab waveguide layer 20 form a ridge waveguide structure.

[0058] In one embodiment, if Figure 2 As shown, the projection of the first doping structure 41 on the preset plane is a fan ring. In this way, compared with the case where the projection of the first doping structure 41 on the preset plane is a ring, the overlapping area between the first doping structure 41 and the coupling waveguide 30 can be reduced, thereby reducing the light loss in the coupling waveguide 30.

[0059] In practical applications, the first doping region 41A and the second doping region 41B may include either N-type doping or P-type doping; correspondingly, the third doping region 42A and the fourth doping region 42B may include either P-type doping or N-type doping.

[0060] In one embodiment, the first doping region 41A and the second doping region 41B include N-type doping, and the third doping region 42A and the fourth doping region 42B include P-type doping. Among them, the first doping region 41A is an N-type lightly doped region, and the second doping region 41B is an N-type heavily doped region; the third doping region 42A is a P-type heavily doped region, and the fourth doping region 42B is a P-type lightly doped region. Here, relative to the situation where the fourth doping region 42B includes N-type doping and the first doping region 41A includes P-type doping, under the same voltage, the carriers in the P-type doping region are holes, so that more refractive index changes can be generated, and the loss is lower. Therefore, when the fourth doping region 42B close to the coupling waveguide 30 includes P-type doping, the modulation efficiency of the microring modulator is higher.

[0061] In practical applications, the first doping region 41A (N-type lightly doped region) and the fourth doping region 42B (P-type lightly doped region) are in physical contact to form a vertical PN junction, and the carrier type in the depletion region near the P-type lightly doped region in the vertical PN junction is electrons. When a reverse bias is applied to the electrode 50, the carriers distributed in the PN junction will be drawn away. In the above embodiment, since the P-type lightly doped region, that is, the fourth doping region 42B is closer to the coupling waveguide 30, the interaction between the carriers and the light waves in the fourth doping region 42B is stronger. At the same time, since the mobility of electrons is much greater than the mobility of holes, when an external voltage is applied to the PN junction, the carriers near the P-type lightly doped region will be drawn away faster, that is, the carrier concentration in the fourth doping region 42B changes faster. Therefore, when the carrier concentration in the fourth doping region 42B close to the coupling waveguide 30 changes faster, the modulation speed is faster. That is, when the fourth doped region 42B close to the coupling waveguide 30 is a P-type lightly doped region, the modulation speed of the micro-disk modulator is faster.

[0062] In one embodiment, the top surface of the coupling waveguide 30 is flush with the top surface of the second doping structure 42. On the one hand, the top surface of the coupling waveguide 30 is flush with the top surface of the second doping structure 42, which can enhance the coupling effect and improve the interaction between the optical mode field and the carriers; on the other hand, the coupling waveguide 30 and the second doping structure 42 can be completed in the same process, thereby simplifying the process.

[0063] In one embodiment, the first doping structure 41 is located in the slab waveguide layer 20 and the top surface of the first doping structure 41 is flush with the top surface of the slab waveguide layer 20. In practical applications, the first doping structure 41 is made of the same material as the slab waveguide layer 20, and the first doping structure 41 is obtained by doping a portion of the slab waveguide layer 20 after the slab waveguide layer 20 is formed. It can be understood that the first doping structure 41 and the slab waveguide layer 20 can be completed in the same process, thereby simplifying the process. In addition, light loss caused by a structural mutation between the first doping structure 41 and the slab waveguide layer 20 can be avoided.

[0064] In one embodiment, if Figure 2 and Figure 3 As shown, the projection of the coupling waveguide 30 on the preset plane is a long strip; the projections of the first doping region 41A and the second doping region 41B on the preset plane are both fan-shaped, the projection of the third doping region 42A on the preset plane is a circle, and the projection of the fourth doping region 42B on the preset plane is a ring. In other words, the micro-disk resonant structure 40 includes a disk-shaped modulation region, and the disk-shaped modulation region changes the concentration of carriers by applying an external voltage, thereby changing the effective refractive index of the modulation region, thereby realizing the constructive and destructive phase of light.

[0065] It should be noted that Figure 1 , Figure 2 and Figure 3 This is only an example of a micro-disk modulator provided in an embodiment of the present invention, and is not intended to limit the structure of the micro-disk modulator in the present invention.

[0066] In practical applications, the coupling waveguide 30 may be a straight waveguide. When light waves enter from the input end of the straight waveguide and meet the resonance condition, the light waves are coupled into the microdisk. When the light waves at the input end do not meet the resonance condition, the light waves will not be coupled into the microdisk.

[0067] In one embodiment, the diameter width of the physical contact point between the first doping region 41A and the fourth doping region 42B may range from 300 nanometers to 600 nanometers.

[0068] In practical applications, in order to improve the efficiency of the micro-disk modulator, the width of the PN junction should cover the range of the light wave mode field in the micro-disk as much as possible, but the width of the PN junction should not be too large, otherwise it will lead to a reduction in the bandwidth of the micro-disk modulator. Generally, the width of the PN junction is selected between 300 nanometers and 600 nanometers. In the above embodiment, a vertical PN junction is formed at the physical contact between the first doping region 41A and the fourth doping region 42B, and the width of the PN junction is the diameter width at the physical contact between the first doping region 41A and the fourth doping region 42B.

[0069] In one embodiment, the electrode 50 includes a first electrode 51 and a second electrode 52; wherein the first electrode 51 is located in the second doping region 41B, and the second electrode 52 is located in the third doping region 42A. Here, the first electrode 51 and the second electrode 52 are positive and negative electrodes, respectively, and are connected to the micro-disk resonant structure 40 to form a loop. The materials of the first electrode 51 and the second electrode 52 may include at least one conductive material, such as gold, copper, aluminum, silver and / or other appropriate metal materials.

[0070] In practical applications, the projection of the first electrode 51 on the preset plane is a fan-shaped ring; the projection of the second electrode 52 on the preset plane is a circle. That is, the shape of the first electrode 51 includes a fan-shaped cylinder; the shape of the second electrode 52 includes a cylindrical shape. It should be noted that the first electrode 51 and the second electrode 52 may also include other shapes.

[0071] In one embodiment, the micro-disk modulator further includes a covering layer 11 covering the slab waveguide layer 20, the coupling waveguide 30 and the micro-disk resonant structure 40, and the refractive index of the covering layer 11 is less than the refractive index of the slab waveguide layer 20. Here, the material of the covering layer 11 includes silicon dioxide. It should be noted that the micro-disk modulator may include or exclude the covering layer 11; when the micro-disk modulator includes the covering layer 11, the material of the covering layer 11 may be selected from any material having a refractive index less than the refractive index of the slab waveguide layer 20.

[0072] It should be noted that the solution provided in the embodiment of the present invention is applicable to silicon-based micro-disk modulators, and is also applicable to micro-disk modulators based on III-V group materials such as gallium arsenide (GaAs), indium phosphide (InP) and P-type doped gallium nitride (GaN).

[0073] The micro-disk modulator provided by the embodiment of the present invention comprises: a substrate layer; a planar waveguide layer located on the substrate layer; a coupling waveguide and a micro-disk resonant structure arranged in parallel in the planar waveguide layer, wherein the micro-disk resonant structure comprises a first doping structure and a second doping structure stacked in sequence along the thickness direction of the substrate layer, wherein the first doping structure and the second doping structure have opposite doping types; and an electrode electrically connected to the micro-disk resonant structure. In the embodiment of the present invention, a vertical PN junction electrical modulation structure is formed at the junction of the first doping structure and the second doping structure by stacking the first doping structure and the second doping structure in sequence along the thickness direction of the substrate layer. The vertical PN junction electrical modulation structure can increase the overlapping area between the PN junction depletion region and the light wave mode field, improve the interaction between the light wave and the carrier, and thus improve the modulation efficiency; at the same time, the vertical PN junction electrical modulation structure can reduce the size occupied by the modulation structure, thereby reducing the size of the micro-disk modulator, thereby improving the integration of the photonic integrated chip and reducing the preparation cost. In addition, compared with the micro-ring modulator with a vertical PN junction, the micro-disk modulator has a simple structure, and does not need to continue to form a polycrystalline silicon micro-ring on the silicon material after forming a single-crystal silicon micro-ring.

[0074] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A microdisk modulator, characterized in that: include: substrate layer; a planar waveguide layer located on the substrate layer; A coupled waveguide and a micro-disk resonant structure are arranged in parallel in the planar waveguide layer, wherein the micro-disk resonant structure comprises a first doping structure and a second doping structure which are sequentially stacked in a thickness direction of the substrate layer, wherein the first doping structure is physically connected to the second doping structure, the first doping structure and the second doping structure have opposite doping types, and the projection of the second doping structure on a preset plane is circular, and the preset plane is perpendicular to the thickness direction of the substrate layer; as well as An electrode is electrically connected to the micro-disk resonant structure.

2. The microdisk modulator according to claim 1, characterized in that The first doping structure includes a first doping region and a second doping region with the same doping type as the first doping region and at least partially surrounding the first doping region; the second doping structure includes a third doping region and a fourth doping region with the same doping type as the third doping region and surrounding the third doping region; wherein the first doping structure and the second doping structure are physically connected to the fourth doping region through the first doping region; and the second doping region has no physical contact with the third doping region.

3. The microdisk modulator according to claim 1, characterized in that The projection of the first doping structure on the preset plane is a fan-shaped ring.

4. The microdisk modulator according to claim 2, characterized in that The first doping region and the second doping region include N-type doping, and the third doping region and the fourth doping region include P-type doping.

5. The micro-disk modulator according to claim 2, characterized in that The top surface of the coupling waveguide is flush with the top surface of the second doping structure; the first doping structure is located in the slab waveguide layer and the top surface of the first doping structure is flush with the top surface of the slab waveguide layer.

6. The microdisk modulator according to claim 2, characterized in that The electrodes include a first electrode and a second electrode; wherein the first electrode is located in the second doping region, and the second electrode is located in the third doping region.

7. The microdisk modulator according to claim 2, characterized in that The projection of the coupled waveguide on the preset plane is a long strip; the projections of the first doped region and the second doped region on the preset plane are both fan-shaped, the projection of the third doped region on the preset plane is a circle, and the projection of the fourth doped region on the preset plane is a ring.

8. The microdisk modulator according to claim 7, characterized in that The diameter width of the physical contact point between the first doping region and the fourth doping region ranges from 300 nanometers to 600 nanometers.

9. The microdisk modulator according to claim 1, characterized in that The micro-disk modulator further includes a covering layer covering the planar waveguide layer, the coupling waveguide and the micro-disk resonant structure, and the refractive index of the covering layer is smaller than the refractive index of the planar waveguide layer.

10. The microdisk modulator according to claim 1, wherein: The material of the substrate layer includes silicon dioxide; the material of the planar waveguide layer includes single crystal silicon; the material of the first doping structure includes single crystal silicon; and the material of the second doping structure includes single crystal silicon.

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