CN111934196B

CN111934196B - Electrically-driven on-chip integrated erbium-doped waveguide amplifier and preparation method thereof

Info

Publication number: CN111934196B
Application number: CN202010600408.8A
Authority: CN
Inventors: 王兴军; 周佩奇; 王博; 何燕冬
Original assignee: Peking University
Current assignee: Peking University
Priority date: 2020-06-28
Filing date: 2020-06-28
Publication date: 2021-12-10
Anticipated expiration: 2040-06-28
Also published as: CN111934196A

Abstract

The embodiment of the invention provides an electrically driven on-chip integrated erbium-doped waveguide amplifier and a preparation method thereof, wherein the electrically driven on-chip integrated erbium-doped waveguide amplifier comprises the following steps: the light source comprises a silicon substrate, a DBR bottom reflector, an optical waveguide, a gain medium layer, a DBR top reflector, a bonding layer and a III-V family pumping layer which are sequentially arranged on a light path, wherein the III-V family pumping layer generates pumping light through electroluminescence, the gain medium layer is indirectly driven electrically in the intersecting direction of signal light transmission to generate amplification, and the III-V family semiconductor light source is integrated on the bonding layer in an epitaxial growth or surface mount bonding mode; the DBR bottom reflector and the DBR top reflector form a DBR resonant cavity, and pumping power in the gain medium layer is improved; the optical waveguide and the gain medium layer form a hybrid waveguide structure. The invention adopts the III-V group semiconductor laser as a pump, thus realizing electroluminescence; the III-V group semiconductor laser is integrated on the optical waveguide amplifier in a growth or patch bonding mode, and the process is simple and the cost is low.

Description

Electrically-driven on-chip integrated erbium-doped waveguide amplifier and preparation method thereof

Technical Field

The invention relates to the technical field of photoelectron, in particular to an electrically-driven on-chip integrated erbium-doped waveguide amplifier and a preparation method thereof.

Background

In recent years, the micro-electronics technology is rapidly developed according to moore's law and gradually tends to a bottleneck, and a silicon-based optoelectronic technology for realizing the integration of an optoelectronic device on a chip based on the micro-electronics technology is attracting more and more attention. The method fully exerts the advantages of mature process, high integration level, low cost, low price and the like of the microelectronic technology, and the advantages of high transmission rate, large bandwidth, strong anti-interference capability and the like of optical communication, and plays an increasingly important role in the field of communication. On-chip optoelectronic devices, such as modulators, detectors, wavelength division multiplexers, etc., have grown mature and are being commercialized.

With the increase of the integration level of the on-chip optoelectronic device, the problem of optical signal propagation loss becomes more and more serious. Therefore, how to realize an on-chip optical waveguide amplifier is a problem that must be solved by the development of the current silicon-based optoelectronic technology. However, silicon is an indirect bandgap material, excited radiation requires phonon participation, and the light-emitting efficiency is low, so that it is difficult to implement an on-chip waveguide amplifier. At present, there are two main solutions for solving the on-chip waveguide amplifier: III-V semiconductor material based amplifiers and rare earth ion based erbium doped waveguide amplifiers.

A III-V semiconductor amplifier employs a direct bandgap semiconductor material as a gain medium. The band gap width is adjustable, and different semiconductor materials are adopted, so that the gain in different wavelength ranges can be realized; the preparation process is simple, the process is mature, large-scale production is easy to realize, and the cost is reduced; the electric drive can be realized, an external light source is not needed, and the on-chip integration application is facilitated. Group III-V semiconductor amplifiers have been greatly developed for their superior performance. However, the material itself is difficult to grow epitaxially on a silicon substrate, which is not favorable for silicon-based integration; meanwhile, group III-V semiconductor amplifiers in the 1.5 μm band are difficult to implement, limited by the material bandgap.

Therefore, there is a need for a waveguide amplifier that can be integrated on-chip.

Disclosure of Invention

In order to solve the above problems, embodiments of the present invention provide an electrically driven on-chip integrated erbium-doped waveguide amplifier and a method for manufacturing the same.

In a first aspect, an embodiment of the present invention provides an electrically driven on-chip integrated erbium-doped waveguide amplifier, including: silicon substrate, DBR bottom reflector, optical waveguide, gain medium layer, DBR top reflector, bonding layer and III-V family pumping layer that set gradually on the light path, wherein:

the III-V family pumping layer is used for generating pumping light through electroluminescence, the gain medium layer is indirectly electrically driven to amplify in the intersecting direction of signal light transmission, and the III-V family semiconductor light source is integrated on the bonding layer in an epitaxial growth or patch bonding mode;

the DBR bottom reflector and the DBR top reflector form a DBR resonant cavity, and the DBR resonant cavity is used for improving the pumping power in the gain medium layer;

the optical waveguide and the gain medium layer form a hybrid waveguide structure.

Preferably, the gain medium layer is made of erbium-doped material.

Preferably, the gain medium layer is: a mixture of erbium-doped material and silicon nitride.

Preferably, the gain medium layer is located in a vertical direction of the DBR resonance cavity so that the pump light can resonate in the gain medium layer.

Preferably, the materials of the DBR resonant cavity are silicon dioxide and silicon nitride.

Preferably, the optical waveguide is an on-chip SOI waveguide.

Preferably, the group iii-v pumping layer is a group iii-v LED active layer composed of group iii-v semiconductor light sources.

In a second aspect, an embodiment of the present invention provides a method for manufacturing an electrically driven on-chip integrated erbium-doped waveguide amplifier, including:

alternately depositing silicon dioxide and silicon nitride on a silicon substrate to form a DBR structure;

alternately depositing for a preset number of times according to silicon dioxide and silicon nitride with preset thickness to form a grating below the DBR;

depositing silicon on the grating below the DBR, and forming a silicon waveguide structure by coating, exposing, developing and etching through a photoetching method;

depositing erbium materials on the grating below the DBR except the silicon waveguide to form a gain medium layer;

depositing silicon dioxide and silicon nitride on the gain medium layer to form an upper DBR grating, and alternately depositing twice;

depositing a buffer layer on the grating above the DBR;

and integrating the III-V group semiconductor laser on the buffer layer by epitaxial growth or patch bonding.

Preferably, the iii-v semiconductor laser is integrated on the buffer layer by epitaxial growth or by means of die bonding, and specifically includes:

depositing a silicon dioxide or silicon nitride film on the III-V group semiconductor laser by adopting PECVD as a bonding dielectric layer;

chemically and mechanically polishing the bonding medium layer to ensure that the surface roughness of the bonding medium meets the bonding requirement;

reducing the hydrogen and water content in the bonding medium by thermal annealing, and performing surface activation by RIE;

Preferably, the thickness of the erbium material is an integer multiple of a half wavelength of the pump light.

The embodiment of the invention provides an electrically-driven on-chip integrated erbium-doped waveguide amplifier and a preparation method thereof.A III-V group semiconductor laser is used as a pump to realize electroluminescence and complete integration of a silicon-based optical waveguide amplifier without an external pump light source; meanwhile, the III-V group semiconductor laser is integrated on the optical waveguide amplifier in a growth or patch bonding mode, so that the process is simple and the cost is low.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of an electrically driven on-chip integrated erbium-doped waveguide amplifier according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating reflectivity spectra of a grating at different periods according to an embodiment of the present invention;

FIG. 3 is a graph showing the reflectivity change at 980nm for different grating periods according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating the enhanced effect of the pump light in the lower cavity with different numbers of grating cycles in the embodiment of the present invention compared to the pump light without the DBR structure;

FIG. 5 is a diagram illustrating the distribution of the optical field in the erbium material in an embodiment of the present invention;

FIG. 6 is a schematic diagram of an amplifier fabrication process according to an embodiment of the present invention;

fig. 7 is a flowchart of a method for manufacturing an electrically driven on-chip integrated erbium-doped waveguide amplifier according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

At present, on-chip amplification is a necessary technology in a silicon-based optoelectronic chip, but a reliable on-chip waveguide amplifier is still not completely realized; although erbium doped materials are well known as suitable materials for optical amplifiers, erbium doped optical waveguide amplifiers cannot be directly electrically pumped and conventional waveguide structures cannot meet the requirements by confining most of the signal light to silicon.

The embodiment of the invention realizes an electrically driven on-chip integrated adjustable erbium-doped waveguide amplifier. An electrically driven III-V family semiconductor laser is used as a pump, and an erbium-doped material is used as a gain medium, so that the high gain on a chip is realized while the electric drive is realized. By simulating and designing the hybrid waveguide structure, most of power is limited in a gain medium while signal light propagates along the waveguide, so that higher on-chip gain can be realized.

The structure of the waveguide amplifier in the embodiment of the invention is mainly divided into three important parts: the laser comprises a vertical structure resonant cavity based on distributed Bragg feedback (DBR), a hybrid waveguide structure consisting of a waveguide and a gain medium, and a patch-integrated III-V group semiconductor laser pump.

The III-V group semiconductor laser is integrated on the on-chip waveguide amplifier by adopting a growth or patch bonding mode. The laser with 980nm downward radiation is used as the pumping of the gain medium, so that the problem that the on-chip waveguide amplifier needs external optical pumping and is not beneficial to on-chip integration is solved.

The center of the reflection spectrum of the vertical structure resonant cavity of the distributed Bragg feedback (DBR) is the wavelength of the pump light, and the vertical structure resonant cavity is used for reflecting the pump light. Because the pump light radiated by the III-V group semiconductor laser downwards propagates, the pump power transmitted to the substrate through the gain medium can be dissipated, and more pump light can be limited in the gain medium by designing the DBR resonant cavity with the vertical structure, so that the pumping efficiency is improved, and the gain is improved.

The waveguide structure for signal light propagation adopts a hybrid waveguide structure. To realize higher on-chip gain, more signal light is required to be confined in the gain medium, and the overlapping area of the pump light and the signal light in the gain medium is increased, so that the gain is increased.

Fig. 1 is a schematic structural diagram of an electrically driven on-chip integrated erbium-doped waveguide amplifier according to an embodiment of the present invention, where the amplifier includes: a silicon substrate 101, a DBR bottom mirror 102, an optical waveguide 103, a gain medium layer 104, a DBR top mirror 105, a bonding layer 106, and a iii-v pump layer 107 disposed in sequence on an optical path, wherein:

the optical waveguide and the gain medium layer form a hybrid waveguide structure to realize optical field distribution and transmission.

For convenience of description, in all embodiments of the present invention, the signal light with a wavelength of 1.5 μm is amplified by a pump light with a wavelength of 980nm as a waveguide, but the present invention is not limited to the scope of the embodiments of the present invention.

In the figure, the DBR grating close to the silicon substrate is a DBR bottom reflector, the erbium-doped gain material represents a gain medium layer, the upper DBR grating is a DBR top reflector, the buffer layer is a bonding layer, and the III-V semiconductor laser is a III-V pumping layer.

Specifically, in the electrically-driven on-chip integrated erbium-doped waveguide amplifier provided in the embodiment of the present invention, the silicon substrate is disposed on a plane formed by an X axis and a Y axis, the light source for generating the pump light is a layered structure and is uniformly laid on the upper surface of the silicon substrate, and the generated pump light propagates in a direction away from the silicon substrate along the Z axis.

In the embodiment of the invention, the III-V family pumping layer is a III-V family semiconductor light source which is used as a pumping source, pumping light is generated through electroluminescence, and the pumping light indirectly drives the gain medium layer to generate amplification in the intersecting direction of signal light transmission.

The DBR bottom reflector and the DBR top reflector form a DBR resonant cavity together, the DBR resonant cavity is used for improving pumping power in the gain medium layer, and the optical waveguide and the gain medium layer form a mixed waveguide structure to realize distribution and transmission of an optical field.

The embodiment of the invention provides an electrically-driven on-chip integrated erbium-doped waveguide amplifier, wherein a III-V group semiconductor laser is used as a pump, so that electroluminescence is realized, and the complete integration of a silicon-based optical waveguide amplifier without an external pump light source is realized; meanwhile, the III-V group semiconductor laser is integrated on the optical waveguide amplifier in a growth or patch bonding mode, so that the process is simple and the cost is low.

In the prior art, an erbium-doped waveguide amplifier realizes 1.5 μm light amplification by doping erbium ions. Erbium is used as a rare earth element, the light-emitting wavelength is 1.5 mu m, and the erbium-doped fiber amplifier is widely applied to erbium-doped fiber amplifiers. Erbium ions in a ground state are excited to a second excited state through 980nm or 1480nm pumping, and are attenuated to a first excited state through spontaneous radiation, so that population inversion between the first excited state and the ground state is realized, and light amplification is realized. Meanwhile, the erbium ion has long energy level service life and has the advantage of high-speed modulation. Recent research has shown that erbium doped waveguide amplifiers have begun to be integrated with other optical devices in silicon photonic systems.

However, currently all on-chip erbium-doped waveguide amplifiers still require an external pump light source, such as a pump laser for horizontal waveguide coupling. This weakness complicates optoelectronic integration schemes and does not allow complete integration of silica-based optical waveguide amplifiers.

On the basis of the above embodiment, preferably, the gain medium layer is made of an erbium-doped material.

According to the embodiment of the invention, the erbium-doped material is used as the gain medium, so that short-distance high-gain amplification on a chip can be realized.

On the basis of the above embodiment, preferably, the gain medium layer is: a mixture of erbium-doped material and silicon nitride.

In order to improve the quality of the erbium-doped thin film material, a mixed material of an erbium-doped material and silicon nitride is adopted as a gain medium, so that the loss of light waves in the gain medium is reduced.

On the basis of the above embodiment, preferably, the gain medium layer is located in a vertical direction of the DBR resonance cavity, so that the pump light can generate resonance in the gain medium layer.

Specifically, in the waveguide amplifier based on-chip integrated electrical drive provided in the embodiment of the present invention, in order to further improve the pump absorption efficiency in the gain medium layer, it is necessary to improve the pump power intensity in the gain layer.

Specifically, the DBR resonant cavity is made of silicon dioxide and silicon nitride.

In this embodiment, the resonant cavity adopts a Distributed Bragg Reflector (DBR) structure, and the materials are silicon dioxide and silicon nitride. The refractive index of silicon dioxide is 1.44 and the refractive index of silicon nitride is 2. The DBR grating period design, at a duty cycle of 50%, can be found to have a grating period of 288nm, according to the formula Λ ═ λ/2n, and thus the thickness of the alternately deposited silicon dioxide and silicon nitride is 144 nm. The design of the DBR structure optimizes the results by simulation. FIG. 2 is a diagram showing the reflectivity spectrum of the grating at different periods according to an embodiment of the present invention, and as shown in FIG. 2, the reflection bandwidth of the grating is about 300nm (0.85 μm-1.15 μm), and as the period number of the grating increases, the reflection bandwidth of the grating narrows and the reflectivity increases.

Fig. 3 is a schematic diagram illustrating the reflectivity change of 980nm with respect to the center wavelength at different grating periods in the embodiment of the present invention, as shown in fig. 3, in the DBR structure design, the lower grating mainly reflects the light incident to the substrate through the gain medium, and the grating reflectivity needs to be close to 1, so as to ensure that the pump light power is fully used for the absorption of the gain medium, and thus the period number of the lower grating is 10, thereby ensuring the high reflectivity; the reflectivity of the upper grating needs to ensure that more incident optical power is incident into the gain medium, so the reflectivity cannot be too large. Meanwhile, if the reflectivity is too small, sufficient oscillation and absorption of the pump light in the gain medium cannot be ensured.

And simulating the pumping power in the gain medium under the condition that the number of cycles of the lower grating is fixed to 10 and the number of cycles of different upper gratings, and comparing the pumping power in the gain medium with the pumping power in the case that the vertical-direction DBR is not added. Fig. 4 is a schematic diagram illustrating an enhanced effect of the pump light in the cavity without the DBR structure at different cycles of the upper grating in the embodiment of the present invention, as shown in fig. 4, when the number of cycles of the upper grating is 2, the pump power in the cavity reaches a maximum value, and compared with the case of not adding the vertical DBR, the pump power in the cavity is 4 times that in the previous case, thereby achieving a higher gain coefficient of the waveguide amplifier.

On the basis of the above embodiment, preferably, the optical waveguide is an on-chip SOI waveguide.

The embodiment of the invention takes the erbium-doped material as the gain medium, designs the on-chip hybrid waveguide structure by combining the waveguide in order to increase the limiting factor of the signal light in the gain medium, and ensures that the light wave can be more limited in the gain medium while propagating along the waveguide by simulating the structural parameters of the waveguide, thereby realizing higher on-chip gain.

Based on the content of the above embodiment, as an optional embodiment, the gain medium layer may be an erbium material layer, the waveguide may be an on-chip SOI waveguide, and the two may be combined to form a hybrid structure, so as to implement redistribution amplification and transmission of an optical field; alternatively, silicon nitride layers may be alternately added to the gain layers to improve waveguide quality.

The size of the silicon waveguide is designed, so that more pumping light power is limited in a gain medium while the light wave can be transmitted along the waveguide, and the size of the silicon waveguide cannot be too large. In the simulation process, under the condition that the height of the silicon waveguide is fixed to be 220nm, and the width of the silicon waveguide is 250nm, a larger limiting factor of signal light in a gain medium can be ensured; the erbium material of the gain medium is deposited by magnetron sputtering, the thickness of the erbium material is integral multiple of half wavelength of the pump light, and the thickness of the gain medium is 1.3 mu m. However, the thicker gain medium film may be annealed due to too large thermal expansion coefficient, which may cause the film to separate, increase transmission loss, and affect device performance. The thermal expansion coefficient of silicon nitride is opposite to that of erbium material, and the erbium material and the silicon nitride can be alternatively deposited, so that the film quality of the erbium material is still better after annealing.

Fig. 5 is a schematic diagram showing the optical field distribution in the erbium material according to the embodiment of the present invention, and as shown in fig. 5, the optical field is distributed sinusoidally in the gain medium due to the DBR structure on both sides. The alternating deposition of erbium material and silicon nitride is designed according to the distribution of optical field, the silicon nitride is deposited at the position with low optical field power, and the erbium silicate is deposited at the position with high optical field power, so that the film quality of erbium material can be ensured under the condition of not reducing gain.

And simulates the high-speed modulation characteristic of the device, when the same bias current is injected, the response amplitude is increased along with the increase of the frequency of the input signal and then is reduced. The frequency of the input signal corresponding to a response amplitude of-3 dB is defined as the device bandwidth. At room temperature, the maximum bandwidth is about 42GHz and the bias current is 30 mA. Such large bandwidth characteristics are predictive of the high speed modulation characteristics of the device.

On the basis of the above embodiments, preferably, the iii-v group pumping layer is a iii-v group LED active layer composed of iii-v group semiconductor light sources.

The semiconductor laser has the advantages of small volume, light weight, high photoelectric conversion rate, low cost and the like, and is widely applied to various fields. Because it is difficult to perform epitaxial growth on a silicon substrate, in this study, iii-v group semiconductor lasers are integrated onto optical waveguide amplifiers in a growth or patch bonding manner. The bonding buffer layer adopts silicon dioxide or silicon nitride, and achieves the bonding requirement through mechanical polishing, annealing and other modes, and finally, the III-V group semiconductor laser is integrated on the waveguide amplifier through an epitaxial paster mode.

In summary, the main points of the embodiments of the present invention are as follows:

1) and the structure design of the on-chip optical waveguide amplifier: in the embodiment of the invention, an erbium-doped material is used as a gain medium, an on-chip hybrid waveguide structure is designed by combining a waveguide for increasing the limiting factor of signal light in the gain medium, and the structural parameters of the waveguide are designed through simulation, so that more light waves can be limited in the gain medium while being transmitted along the waveguide, and higher on-chip gain is realized; meanwhile, in order to improve the quality of the erbium-doped thin film material, a mixed material of an erbium-doped material and silicon nitride is adopted as a gain medium, so that the loss of the light wave in the gain medium is reduced.

2) And III-V group semiconductor laser on-chip integration: erbium-doped optical waveguide amplifiers are not favorable for on-chip integration applications because of the difficulty in realizing electric pumps and the need for external light sources for optical pumps. In the embodiment of the invention, a growth or patch bonding mode is adopted, the III-V group semiconductor is integrated on the waveguide amplifier, 980nm laser is generated by electric pumping and is used as pumping of a gain medium, and therefore the on-chip electric drive waveguide amplifier is realized.

3) And designing a vertical structure resonant cavity: in the embodiment of the invention, the III-V group semiconductor laser is integrated above the waveguide amplifier in a growth or surface mounting mode, the emergent light is downward, and the pump light is transmitted through the gain medium and then is transmitted to the substrate to be dissipated. In order to improve the pumping utilization rate, a vertical resonant cavity structure is designed, so that the pumping light can resonate in the gain medium, the utilization efficiency of the pumping light is improved, and the gain is improved.

In summary, the present invention provides a novel electrically driven integrated erbium-doped waveguide amplifier on chip. The advantages of electrically driving the III-V group semiconductor laser and mature preparation process are combined, and the advantages of the erbium-doped waveguide amplifier that the 1.5 mu m high-gain adjustable optical amplification can be realized and the erbium-doped waveguide amplifier is easy to integrate with the silicon-based substrate are also combined.

The erbium-doped material is used as a gain medium, so that short-distance high-gain amplification on a chip can be realized; the III-V group semiconductor laser is used as a pump, so that electroluminescence is realized, and complete integration of the silicon-based optical waveguide amplifier without an external pump light source is realized. Meanwhile, the III-V group semiconductor laser is integrated on the optical waveguide amplifier in a growth or patch bonding mode, so that the process is simple and the cost is low; and the DBR grating structure in the vertical direction is adopted to enhance the pumping light intensity, further improve the pumping efficiency and realize higher on-chip gain. Through the combination of the ideas, the advantages of the erbium-doped material and the semiconductor material can be fully exerted, and finally, the high-gain, high-speed and adjustable optical amplification of monolithic integrated electric drive is provided.

Fig. 6 is a schematic diagram illustrating a process for manufacturing an amplifier according to an embodiment of the present invention, and fig. 7 is a flowchart illustrating a method for manufacturing an electrically-driven on-chip integrated erbium-doped waveguide amplifier according to an embodiment of the present invention, as can be seen from fig. 6 and 7, the method includes:

s1, alternately depositing silicon dioxide and silicon nitride on the silicon substrate to form a DBR structure;

s2, depositing silicon dioxide and silicon nitride alternately for a preset number of times according to a preset thickness to form a DBR lower grating;

s3, depositing silicon on the grating below the DBR, and forming a silicon waveguide structure by coating, exposing, developing and etching through a photoetching method;

s4, depositing erbium material on the grating under the DBR except the silicon waveguide to form a gain medium layer;

s5, depositing silicon dioxide and silicon nitride on the gain medium layer to form an upper DBR grating, and alternately depositing twice;

s6, depositing a buffer layer on the upper grating of the DBR;

and S7, integrating the III-V group semiconductor laser on the buffer layer by means of epitaxial growth or patch bonding.

Specifically, a silicon dioxide or silicon nitride film is deposited on the III-V group semiconductor laser by adopting PECVD as a bonding medium layer;

First, silicon dioxide and silicon nitride are alternately deposited on a silicon substrate to form a DBR structure.

And according to the simulation result, silicon dioxide and silicon nitride with the thickness of 144nm are alternately deposited for 10 times to form the lower grating.

And depositing silicon on the silicon waveguide structure, and performing gluing, exposure, development and etching by using a traditional photoetching method to form the silicon waveguide structure. Conventional silicon waveguides are typically 220nm in height. Since the optical field needs to be limited in the gain medium as much as possible, thereby realizing a larger limiting factor and higher gain, the width of the silicon waveguide cannot be too large, and is 250 nm.

Next, erbium material is deposited. Because the DBR structure is designed in the vertical direction, the pump light is required to resonate in the gain medium, so that the thickness of the erbium material is required to meet the integral multiple of the half wavelength of the pump light, and the thickness of the gain medium is 1.3um which is twice of the wavelength of the pump light in the gain medium.

Erbium materials are deposited by magnetron sputtering and require activation of optical activity by annealing. However, when the erbium material is thicker, annealing can cause film cracking, and thus alternate deposition with silicon nitride improves film quality. In order not to affect the gain of the gain medium to the signal light, silicon nitride is deposited on the portion with weaker light intensity distribution of the pump light.

Next, silicon dioxide, silicon nitride is deposited to form the upper DBR, alternating deposition twice.

Finally, it is necessary to integrate iii-v semiconductor lasers into waveguide amplifiers by means of epitaxial growth or by means of a chip. Depositing a silicon dioxide or silicon nitride film on a semiconductor light source by adopting PECVD as a bonding medium layer; then, carrying out chemical mechanical polishing on the bonding medium layer to ensure that the surface roughness of the bonding medium meets the bonding requirement; next, reducing the content of hydrogen and water in the bonding medium by thermal annealing, improving the bonding quality, and performing surface activation by RIE; and finally, integrating the III-V group semiconductor laser on the waveguide amplifier in an epitaxial paster mode.

The embodiment of the invention discloses a preparation method of an electrically-driven on-chip integrated adjustable erbium-doped waveguide amplifier, which is based on an on-chip integrated silicon-based photoelectronic technology, has the advantages of small volume, low cost, high integration level, high communication speed and the like, and is the main trend of future chip development. However, problems that remain unsolved are on-chip light sources and on-chip waveguide amplifiers. Semiconductor lasers and amplifiers based on III-V group compounds become one of the main solutions for solving on-chip light sources and amplifiers due to the advantages of electric drive, high gain, mature technology and the like. However, laser processing around 1550nm is difficult due to the material properties of iii-v compounds themselves, and is not yet commercialized. The invention combines the advantages of the semiconductor laser of III-V family compound and the erbium material, uses the semiconductor laser of 980nm as the pump, and uses the erbium material as the gain medium, thereby realizing the electric drive amplification and fully utilizing the advantages of the erbium material such as high erbium ion concentration and large gain. The semiconductor laser is attached to the waveguide amplifier in the last step in an epitaxial growth or surface mounting mode, the process steps are relatively simple, the cost is low, and the integration and commercialization of the on-chip waveguide amplifier are facilitated. In addition, in order to increase the absorption efficiency of the erbium material to the 980nm pump laser, a distributed Bragg feedback (DBR) structure in the vertical direction is designed, and through simulation design, the pumping power in the cavity is effectively improved, and the gain of the on-chip waveguide amplifier is further improved.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. An electrically driven integrated erbium doped waveguide amplifier on a chip, comprising: silicon substrate, DBR bottom reflector, optical waveguide, gain medium layer, DBR top reflector, bonding layer and III-V family pumping layer that set gradually on the light path, wherein:

the III-V family pumping layer is used for generating pumping light through electroluminescence, the gain medium layer is indirectly electrically driven to generate amplification in the intersecting direction of signal light transmission, and the III-V family semiconductor light source is integrated on the bonding layer in an epitaxial growth or patch bonding mode;

the optical waveguide and the gain medium layer form a hybrid waveguide structure;

the gain medium layer is a mixed material of an erbium-doped material and silicon nitride, and the erbium-doped material and the silicon nitride are arranged in an alternating deposition mode, so that the optical field power of the pump light at the position where the erbium-doped material is deposited is higher than the optical field power of the pump light at the position where the silicon nitride is deposited.

2. The electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 1, characterized in that the gain medium layer is located in a vertical direction of the DBR resonator to enable the pump light to resonate in the gain medium layer.

3. The electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 1, wherein the materials of the DBR cavities are silicon dioxide and silicon nitride.

4. The electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 1, characterized in that the optical waveguide is an on-chip SOI waveguide.

5. The electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 1, wherein the group iii-v pumping layer is a group iii-v LED active layer consisting of group iii-v semiconductor light sources.

6. A method for preparing an electrically driven on-chip integrated erbium-doped waveguide amplifier is characterized by comprising the following steps:

depositing a mixed material of an erbium-doped material and silicon nitride on the grating below the DBR except the silicon waveguide to form a gain medium layer;

depositing a bonding layer on the upper grating of the DBR;

and integrating the III-V semiconductor light source on the bonding layer by means of epitaxial growth or patch bonding.

7. The method for preparing an electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 6, wherein the group III-V semiconductor light source is integrated on the bonding layer by epitaxial growth or patch bonding, and specifically comprises:

depositing a silicon dioxide or silicon nitride film on the III-V group semiconductor light source by adopting PECVD as a bonding dielectric layer;

8. The method of fabricating an electrically driven on-chip integrated erbium-doped waveguide amplifier according to claim 6, characterized in that the thickness of the erbium material is an integer multiple of half the wavelength of the pump light generated by electroluminescence from the group iii-v semiconductor light source.