Method for manufacturing electro-optical modulator and electro-optical modulator

Abstract

The application relates to a preparation method of an electro-optical modulator and the electro-optical modulator. A micro-nano optical fiber substrate is drawn based on a whole transmission optical fiber, opposite positive and negative tuning electrode plates are prepared in a coupling area of the micro-nano optical fiber substrate, an electro-optical waveguide prepared is parallel to the axis of the micro-nano optical fiber substrate, is adsorbed to the coupling area of the micro-nano optical fiber substrate and is located between the positive and negative tuning electrode plates, finally, the coupling area of the micro-nano optical fiber substrate with the adsorbed electro-optical waveguide is encapsulated to obtain the electro-optical modulator. Since the micro-nano optical fiber substrate is directly drawn from the transmission optical fiber, the parallel waveguide coupling structure is formed by adsorbing the electro-optical waveguide to the micro-nano optical fiber substrate, high-speed electro-optical modulation is realized, the input and output of wideband optical signals can be directly completed in the micro-nano optical fiber substrate, no additional optical fiber fusion or optical fiber coupling is needed, the electro-optical modulator belongs to a full optical fiber type electro-optical modulator, and the insertion loss of the electro-optical modulator is significantly reduced.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and in particular to a method for preparing an electro-optic modulator and the electro-optic modulator itself. Background Technology

[0002] With the popularization of big data, the Internet of Things, and artificial intelligence technologies, the communications industry has developed rapidly. Fiber optic communication, with its advantages of wide transmission bandwidth, high anti-interference capability, and low signal attenuation, has surpassed other communication methods such as cable and microwave communication, becoming the most important signal transmission method in the communications industry. Among them, the electro-optic modulator is a key component of fiber optic communication, which can realize electro-optic conversion and information loading, converting high-speed electrical signals into optical signals for high-speed, high-capacity, and long-distance transmission through optical fibers, playing an important role in the transmission quality of fiber optic communication.

[0003] In traditional optical fiber communication, electro-optic modulators are mainly classified into four categories based on their materials: lithium niobate modulators, InP-based modulators, silicon-based modulators, and organic polymer modulators. Benefiting from low waveguide loss and high electro-optic efficiency, lithium niobate electro-optic modulators have become the most widely used modulators in optical fiber communication. However, since current electro-optic modulators almost all use optical waveguides to construct Mach-Zehnder interferometer structures, both the input and output ends of broadband optical signals need to be coupled to pigtails, resulting in significant insertion loss (generally greater than 3dB). Summary of the Invention

[0004] Therefore, it is necessary to provide a method for fabricating an electro-optic modulator and an electro-optic modulator to address the technical problem of high insertion loss in traditional electro-optic modulators.

[0005] A method for fabricating an electro-optic modulator, the method comprising:

[0006] Relative positive and negative tuning electrode plates are fabricated in the coupling region of a micro / nano fiber substrate, wherein the micro / nano fiber substrate is drawn based on a transmission fiber.

[0007] An electro-optic waveguide is attached to the coupling region of the micro-nano fiber substrate along the axial direction of the micro-nano fiber substrate and located between the positive and negative tuning electrode plates. The electro-optic waveguide is made of a material with electro-optic effect.

[0008] The coupling region of the micro / nano fiber substrate with adsorbed electro-optic waveguide is encapsulated to obtain an electro-optic modulator.

[0009] In one embodiment, the electro-optic waveguide is a lithium niobate nanowire.

[0010] In one embodiment, the method further includes:

[0011] Determine the coupling wavelength of the lithium niobate nanowires;

[0012] The target design size of the lithium niobate nanowires was obtained based on the coupling wavelength analysis, and the lithium niobate nanowires were fabricated based on the target design size.

[0013] In one embodiment, the Z-axis of the lithium niobate nanowire located between the positive and negative tuning electrode plates is aligned with the direction of the electric field generated by the positive and negative tuning electrode plates.

[0014] In one embodiment, the transmission fiber is a common single-mode fiber, a photonic crystal fiber, or a microstructure fiber.

[0015] In one embodiment, the micro / nano fiber substrate is obtained by drawing the transmission fiber using a cyclic tapering and oxyhydrogen flame melting method.

[0016] In one embodiment, the positive and negative tuning electrode plates are parallel plate electrodes made of gold.

[0017] In one embodiment, the fabrication of opposing positive and negative tuning electrode plates in the coupling region of the micro / nano fiber substrate includes:

[0018] Gold material is uniformly vapor-deposited in the coupling region of the micro / nano fiber substrate, and a gold film layer of a preset thickness is obtained by controlling the vapor deposition parameters.

[0019] The middle region of the gold film layer is removed by focused ion beam micro-nano processing method, and opposite positive and negative gold parallel plate electrodes are obtained by etching.

[0020] Gold wires were welded to the positive and negative gold parallel plate electrodes using a femtosecond laser welding method to obtain opposing positive and negative tuning electrode plates.

[0021] In one embodiment, encapsulating the coupling region of the micro / nano fiber substrate to which the electro-optic waveguide is adsorbed to obtain an electro-optic modulator includes:

[0022] The coupling region of the micro / nano fiber substrate on which the electro-optic waveguide is adsorbed is filled with aerogel and cured by ultraviolet light.

[0023] An electro-optic modulator is obtained by strengthening the packaging through microwave packaging technology for optoelectronic devices.

[0024] In one embodiment, an electro-optic modulator is provided, including a micro / nano fiber substrate, positive and negative tuning electrode plates, and an electro-optic waveguide. The positive and negative tuning electrode plates are disposed in the coupling region of the micro / nano fiber substrate, and the electro-optic waveguide is adsorbed onto the coupling region of the micro / nano fiber substrate along the axial direction of the micro / nano fiber substrate and is located between the positive and negative tuning electrode plates.

[0025] The aforementioned method for fabricating an electro-optic modulator and the electro-optic modulator are based on a micro / nano fiber substrate obtained by drawing a single piece of transmission fiber. Opposite positive and negative tuning electrode plates are fabricated in the coupling region of the micro / nano fiber substrate. An electro-optic waveguide, parallel to the axis of the micro / nano fiber substrate, is then adsorbed onto the coupling region of the micro / nano fiber substrate, positioned between the positive and negative tuning electrode plates. Finally, the coupling region of the micro / nano fiber substrate with the adsorbed electro-optic waveguide is encapsulated to obtain the electro-optic modulator. Because this application uses a micro / nano fiber substrate obtained by directly drawing a transmission fiber, and then uses an electro-optic waveguide adsorbed onto the micro / nano fiber substrate to form a parallel waveguide coupling structure, high-speed electro-optic modulation is achieved. The input and output of broadband optical signals can be directly completed within the micro / nano fiber substrate without additional fiber splicing or fiber coupling, making it an all-fiber electro-optic modulator, which significantly reduces the insertion loss of the electro-optic modulator. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of a method for fabricating an electro-optic modulator in one embodiment;

[0027] Figure 2 This is a schematic diagram of the drawing process of a micro / nano fiber substrate in one embodiment;

[0028] Figure 3 This is a schematic flowchart of the fabrication method of the electro-optic modulator in another embodiment;

[0029] Figure 4 This is a schematic flowchart illustrating the steps for preparing the positive and negative tuning electrode plates in one embodiment.

[0030] Figure 5 This is a flowchart illustrating the packaging steps of an electro-optic modulator in one embodiment.

[0031] Figure 6 This is a schematic diagram illustrating the working principle of an electro-optic modulator in one embodiment. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0034] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0035] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0036] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0037] As described in the background section, with the popularization of big data, the Internet of Things, and artificial intelligence technologies, the communication industry has developed rapidly. Optical fiber communication, with its advantages of wide transmission bandwidth, high anti-interference capability, and low signal attenuation, has surpassed other communication methods such as cable and microwave communication, becoming the most important signal transmission method in the communication industry. Among these, electro-optic modulators are key components in optical fiber communication, enabling electro-optic conversion and information loading. They convert high-speed electrical signals into optical signals for high-speed, high-capacity, and long-distance transmission through optical fibers, playing a crucial role in the transmission quality of optical fiber communication. In traditional technologies, electro-optic modulators in optical fiber communication are mainly classified into four categories based on materials: lithium niobate modulators, InP-based modulators, silicon-based modulators, and organic polymer modulators. Benefiting from low waveguide loss and high electro-optic efficiency, lithium niobate electro-optic modulators have become the most widely used modulators in optical fiber communication. However, since current electro-optic modulators almost all use optical waveguides to construct Mach-Zehnder interferometer structures, both the input and output ends of broadband optical signals need to be coupled to the pigtail, resulting in significant insertion loss (generally greater than 3dB).

[0038] Based on this, this application proposes a method for fabricating an optoelectronic modulator to solve the technical problem of high insertion loss in traditional electro-optic modulators.

[0039] In one embodiment, such as Figure 1 As shown, a method for fabricating an electro-optic modulator is provided, the method comprising the following steps S100 to S600, wherein:

[0040] S100: Relative positive and negative tuning electrode plates are fabricated in the coupling region of a micro / nano fiber substrate, wherein the micro / nano fiber substrate is drawn based on a transmission fiber.

[0041] Among them, micro-nano optical fiber is the substrate element for fabricating electro-optic modulator. The coupling region it contains is a micro-nano optical fiber segment with a diameter in the micrometer to nanometer range and a constant size. Electro-optic waveguide and positive and negative tuning electrode plates that apply voltage to the electro-optic waveguide to generate electro-optic effect are set in this region. As the substrate of electro-optic modulator, it is conducive to the occurrence of waveguide directional coupling effect, thereby realizing the intensity modulation of broadband optical signal.

[0042] Specifically, there is no single way to fabricate opposing positive and negative tuning electrode plates in the coupling region of the micro / nano fiber substrate. Methods such as magnetron sputtering, electron beam evaporation, thermal evaporation, and electroplating can be used to fabricate these plates. Alternatively, positive and negative tuning electrode plates can be fabricated at corresponding positions in the coupling region of the micro / nano fiber substrate, or a single tuning electrode plate can be fabricated, and then the intermediate region can be removed using etching based on the spacing between the two electrode plates to obtain the opposing positive and negative tuning electrode plates.

[0043] Furthermore, the micro / nano fiber substrate is obtained by drawing a single piece of transmission fiber. Besides the coupling region, the drawn micro / nano fiber substrate may also include transition regions at both ends. These transition regions may include a tapered region and a region with the original diameter. It can be understood that the diameter of the tapered region gradually changes from the original diameter of the transmission fiber to the micrometer- to nanometer-scale diameter of the coupling region as the drawing process proceeds.

[0044] It is understood that the taper of the aforementioned tapered region is determined by the drawing method, and the taper of this region will affect the overall insertion loss of the micro / nano fiber during broadband optical signal transmission. Therefore, in order to minimize transmission loss during optical transmission, this application requires control over the taper of the tapered region. In one embodiment, the micro / nano fiber substrate is obtained based on the transmission fiber through cyclic tapering and oxyhydrogen flame melting. The transmission fiber can be implemented using ordinary single-mode fiber, photonic crystal fiber, or microstructured fiber.

[0045] The following explanation uses ordinary single-mode fiber as an example to illustrate the process of drawing micro / nano fiber substrates based on transmission fiber through cyclic tapering and oxyhydrogen flame melting.

[0046] Specifically, such as Figure 2 As shown, the steps for obtaining micro / nano fiber substrates based on transmission optical fibers through cyclic tapering and oxyhydrogen flame melting include:

[0047] The first motion clamp and the second motion clamp are fixed in the preset clamping position of the ordinary single-mode optical fiber, and the hydrogen-oxygen flame output device is set in the preset heating position of the ordinary single-mode optical fiber.

[0048] During the first preset time period, while outputting hydrogen-oxygen flame heating, the first motion clamp is controlled by the first long stroke displacement platform to move in the first direction at the first preset speed V0, and the second motion clamp is controlled by the second long stroke displacement platform to move in the first direction at the second preset speed V1.

[0049] During the second preset time period, while the hydrogen-oxygen flame is output for heating, the first motion clamp is controlled by the first long-stroke displacement platform to move in the second direction at the second preset speed V1, and the second motion clamp is controlled by the second long-stroke displacement platform to move in the second direction at the first preset speed V0.

[0050] The process is repeated for two preset time periods until a micro / nano fiber substrate with a preset diameter is obtained.

[0051] The running time of the first preset time period and the second preset time period can be the same, both being T, and the first direction and the second direction are opposite directions.

[0052] It can be understood that after the aforementioned first preset time period, the stretching degree of the ordinary single-mode fiber is from L0 = V0 × T in the first direction to L1 = V1 × T. That is, the single-mode fiber of length L0 is stretched by ΔL = L1 - L0 after being heated by the oxyhydrogen flame, and the heated portion of the single-mode fiber is uniformly thinned. After the aforementioned second preset time period, the single-mode fiber is again stretched from L0 = V0 × T in the second direction to L1 = V1 × T, achieving a stretching length of ΔL = L1 - L0.

[0053] Considering the first and second preset time periods as a single time cycle, the deformation of a typical single-mode optical fiber is 2ΔL. The fiber length L0, located midway between the two ΔL stretches, is stretched twice; that is, the length of the fiber at the midway point L0 remains unchanged, but its diameter is uniformly thinned. Therefore, this L0 length portion can be considered the coupling region, and the 2ΔL region can be considered the transition region.

[0054] After N cycles of the first and second preset time periods, the single-mode fiber will eventually become a micro / nano fiber including a coupling region and two transition regions. The length of the coupling region remains L0, and the transition regions are located at both ends of the coupling region with lengths of N×ΔL respectively. Thus, the total length of the micro / nano fiber is L=2NΔL+L0. Assume that the diameter of the coupling region of the micro / nano fiber fabricated in this process is D. (N) By utilizing materials with the same volume and diameter D (N)It can be calculated using the following formula:

[0055] L0 = V0 × T

[0056] L1 = N(V1 - V0)

[0057] D (N) =D*(V0 / V1) N

[0058] In the formula, D is the diameter of a standard single-mode fiber, and N is the number of cycles. By controlling parameters such as the moving speed, running time, and number of cycles of the long-stroke displacement platform during the drawing process, the diameter of the final coupling region can be controlled. Then, based on the diameter of the coupling region and the diameter of the standard single-mode fiber, the taper of the tapered region can be obtained, minimizing the transmission loss during optical transmission.

[0059] In this embodiment, since the micro / nano fiber substrate used for transmission is drawn from ordinary single-mode communication fiber, the transmission of broadband optical signals is directly completed within the micro / nano fiber substrate. This eliminates the need for constructing a Mach-Zehnder interferometer structure using optical waveguides, and consequently avoids the fusion splicing and coupling process between the optical waveguide and the transmission fiber. This significantly reduces the insertion loss of the prepared electro-optic modulator. Furthermore, since the beginning and end of the drawn micro / nano fiber substrate are both the original diameter region (i.e., the original single-mode fiber), extremely low-loss fusion splicing between it and the broadband light source and the output fiber at the end can be achieved using existing fusion splicers, thereby enabling low-loss long-distance signal transmission.

[0060] S400: An electro-optic waveguide is attached to the coupling region of a micro / nano fiber substrate along the axial direction of the substrate and is located between positive and negative tuning electrode plates. The electro-optic waveguide is made of a material with electro-optic effect.

[0061] The electro-optic waveguide is a component that forms a parallel waveguide coupling structure with the micro / nano fiber substrate. When an optical signal passes through the micro / nano fiber substrate, a waveguide directional coupling effect occurs at wavelengths where the effective refractive indices of both are equal. This causes light at that wavelength in the core of the micro / nano fiber substrate to be coupled to the electro-optic waveguide and radiated outwards, thus forming a loss band in the output spectrum of the micro / nano fiber substrate. Furthermore, since the electro-optic waveguide is made of a material with electro-optic effects, its effective refractive index changes with the external electric field between the positive and negative tuning electrodes, causing a shift in the coupling wavelength in the transmission spectrum. This allows for modulation of the light intensity at the directional coupling wavelength. By applying different voltage signals between the positive and negative tuning electrodes, various forms of intensity modulation of the input optical signal within the micro / nano fiber substrate can be achieved. The material used to fabricate the electro-optic waveguide is not unique and can include lithium niobate, KDP-potassium dihydrogen phosphate, gallium arsenide, or cadmium telluride, among others.

[0062] Based on this, the electro-optic waveguide needs to be adsorbed onto the coupling region of the micro / nano fiber substrate along its axial direction, thereby forming a parallel waveguide coupling structure with the micro / nano fiber substrate. Specifically, after fabricating opposing positive and negative tuning electrode plates in the coupling region of the micro / nano fiber substrate, the electro-optic waveguide can be adsorbed onto the coupling region of the micro / nano fiber substrate along its axial direction, located between the positive and negative tuning electrode plates. Then, under the modulation of the external electric field between the positive and negative tuning electrode plates, the electro-optic effect of the electro-optic waveguide enables various forms of intensity modulation of the input optical signal within the micro / nano fiber substrate.

[0063] It is understood that electro-optic waveguides can also be fabricated using micro- and nano-scale processes to achieve diameters in the micrometer to nanometer range, thereby matching their dimensions with the micro- and nano-fiber substrate to enhance the directional coupling effect. Therefore, in this embodiment, the electro-optic waveguide is a nanowire electro-optic waveguide. Correspondingly, the electro-optic waveguide can be lithium niobate nanowires, KDP-potassium dihydrogen phosphate nanowires, gallium arsenide nanowires, or cadmium telluride nanowires, etc. Furthermore, when the electro-optic waveguide is a nanowire electro-optic waveguide, both the nanowire electro-optic waveguide and the micro- and nano-fiber substrate are micro- and nano-scale components. The adsorption between the two can be achieved through micromanipulation techniques, using microprobes to manipulate the nanowire electro-optic waveguide to be placed parallel to the axis of the micro- and nano-fiber substrate at a designated position above the coupling region of the micro- and nano-fiber substrate. The two can then be adsorbed based on the van der Waals forces between the nanowires, forming a parallel waveguide coupling structure. It is understandable that micromanipulation technology is a high-precision micro-operating system that can achieve multi-dimensional attitude control and rapid, efficient, and precise transfer of nanowire electro-optic waveguides based on fine motion control capabilities and real-time camera monitoring, thereby improving the waveguide directional coupling effect.

[0064] Furthermore, the fabrication of electro-optic waveguides and micro / nano fiber substrates can be completed in advance before the fabrication of electro-optic modulators, or can be completed simultaneously with the fabrication of electro-optic modulators, without limitation.

[0065] S600: The coupling region of a micro / nano fiber substrate with adsorbed electro-optic waveguides is encapsulated to obtain an electro-optic modulator.

[0066] Specifically, the stability of the prepared optoelectronic modulator can be improved by filling and encapsulating the trenches and gaps in the coupling region. The encapsulation method is not unique; it can involve first filling the gaps with aerogel or insulating buffer material, and then encapsulating the outer surface with a reinforcing material to obtain the encapsulated electro-optic modulator.

[0067] The above-described method for fabricating an electro-optic modulator involves drawing a single piece of transmission fiber to obtain a micro / nano fiber substrate, fabricating opposing positive and negative tuning electrode plates in the coupling region of the micro / nano fiber substrate, and then attaching an electro-optic waveguide parallel to the axis of the micro / nano fiber substrate to the coupling region of the micro / nano fiber substrate, positioned between the positive and negative tuning electrode plates. Finally, the coupling region of the micro / nano fiber substrate with the attached electro-optic waveguide is encapsulated to obtain the electro-optic modulator. Because this application uses a micro / nano fiber substrate directly drawn from a transmission fiber, and then uses an electro-optic waveguide attached to the micro / nano fiber substrate to form a parallel waveguide coupling structure, high-speed electro-optic modulation is achieved. The input and output of broadband optical signals can be directly completed within the micro / nano fiber substrate without additional fiber splicing or coupling, making it an all-fiber electro-optic modulator, which significantly reduces the insertion loss of the electro-optic modulator.

[0068] In one embodiment, the electro-optic waveguide is a lithium niobate nanowire. The lithium niobate nanowire can be fabricated using a mature lithium niobate wafer fabrication process. Specifically, a lithium niobate thin film with a thickness reaching micro-nano dimensions can be fabricated first from the lithium niobate wafer, and then lithium niobate nanowires can be fabricated based on the lithium niobate thin film. It is understood that the method of shrinking the size from lithium niobate wafers and thin films to lithium niobate nanowires is not unique; it can be achieved through grinding and polishing of the lithium niobate wafer or thin film, or through conventional photolithography processes.

[0069] In this embodiment, the electro-optic waveguide is made of lithium niobate material with excellent electro-optic effect, which makes the prepared electro-optic modulator have advantages such as fast response speed, low driving voltage and low power consumption.

[0070] In one embodiment, such as Figure 3 As shown, the above-mentioned method for fabricating an electro-optic modulator further includes the following steps S200 to S300, wherein:

[0071] S200: Determine the coupling wavelength of the lithium niobate nanowires.

[0072] The coupling wavelength is the wavelength corresponding to the effective refractive index when the lithium niobate nanowire and the micro / nano fiber substrate undergo waveguide directional coupling effect. In this case, the light at this wavelength in the core of the micro / nano fiber substrate will be coupled to the lithium niobate nanowire and radiated out, thus forming a loss band in the output spectrum.

[0073] Specifically, to facilitate the modulation of broadband optical signals using the prepared electro-optic modulator, the coupling wavelength of the lithium niobate nanowire can be determined based on a specified wavelength in the communication band of the broadband optical signal. When no voltage is applied to the lithium niobate nanowire, the optical signal at the coupling wavelength (i.e., the specified wavelength in the communication band of the broadband optical signal) is almost entirely coupled to the lithium niobate nanowire and radiated outwards, resulting in a very low output light intensity. However, when the electric field of the positive and negative tuning electrodes is controlled, causing the applied voltage to the lithium niobate nanowire to change from 0 to a half-wave voltage, the effective refractive index of the lithium niobate nanowire gradually increases, the amount of optical signal coupled to the lithium niobate nanowire gradually decreases, the phase gradually changes from 0 to π, and the output light intensity gradually increases.

[0074] S300: The target design size of lithium niobate nanowires was obtained based on coupled wavelength analysis, and lithium niobate nanowires were fabricated based on the target design size.

[0075] The target design dimensions of lithium niobate nanowires can include parameters such as thickness, width, and length. The thickness of the lithium niobate nanowires can be determined based on the thickness of the prepared lithium niobate film. For example, the minimum thickness of lithium niobate films prepared in general production is 0.3 μm (micrometer) and 0.36 μm.

[0076] Specifically, a parallel waveguide coupling structure model formed by lithium niobate nanowires and a micro / nano fiber substrate can be constructed using COMSOL physics simulation software. Then, based on the coupling wavelength (i.e., optimal energy distribution), the mode coupling characteristics of the lithium niobate nanowires and the micro / nano fiber substrate under single-mode conditions can be studied using the finite element method. The target width and length of the lithium niobate nanowires can be gradually optimized and analyzed to ensure that their coupling wavelength without voltage application matches the specified wavelength of the broadband optical signal communication band (the specified wavelength of the typical broadband optical signal communication band is 1550 nm). Furthermore, based on the target design dimensions of the lithium niobate nanowires obtained from the analysis, lithium niobate thin films can be fabricated using photolithography or other polishing processes to obtain lithium niobate nanowires.

[0077] In this embodiment, the coupling wavelength of the lithium niobate nanowire is determined by specifying the wavelength of the communication band based on the broadband optical signal. After analyzing and obtaining the target design size of the lithium niobate nanowire, the lithium niobate nanowire is then fabricated based on the target design size. This method enables the fabricated electro-optic modulator to achieve more convenient light intensity modulation based on half-wave voltage.

[0078] In one embodiment, the Z-axis of the lithium niobate nanowire located between the positive and negative tuning electrode plates is aligned with the direction of the electric field generated by the positive and negative tuning electrode plates.

[0079] Lithium niobate is a crystalline material with three crystal orientations: X, Y, and Z. The dielectric constant components differ depending on the orientation. The largest dielectric constant component is along the Z crystal orientation (γ33 = 32.2 pm / V). Therefore, to fully utilize the largest dielectric constant component γ33 of the lithium niobate crystal and efficiently adjust the refractive index of the lithium niobate nanowires, the direction of γ33 should be aligned with the direction of the applied electric field, i.e., the direction of the electric field generated by the positive and negative tuning electrodes. This ensures the electro-optic modulator achieves maximum efficiency in electro-optic modulation.

[0080] Specifically, when fabricating lithium niobate thin films based on lithium niobate wafers, the tangential direction of the lithium niobate wafer is generally the thickness direction of the lithium niobate thin film. Therefore, X-cut, Y-cut, or Z-cut can be selected when obtaining the lithium niobate thin film. However, when fabricating lithium niobate nanowires based on lithium niobate thin films, X-cut lithium niobate thin films can be processed along the Y-axis of the lithium niobate crystal, and Y-cut lithium niobate thin films can be processed along the X-axis of the lithium niobate crystal. This ensures that the Z-axis direction of the X-cut and Y-cut lithium niobate nanowires is consistent, facilitating the placement of the lithium niobate nanowires on the coupling region of the micro / nano fiber substrate in the same manner. This avoids the inability to achieve the maximum electro-optic modulation effect due to neglecting the placement direction of the Z-axis during fabrication.

[0081] In one embodiment, the positive and negative tuning electrode plates are parallel plate electrodes made of gold. It is understood that the positive and negative tuning electrode plates are two parallel plate electrodes arranged opposite each other and symmetrical about the lithium niobate nanowires, and can be made of conductive metallic materials, such as titanium, gold, chromium, platinum, etc. In this embodiment, the positive and negative tuning electrode plates are made of gold. Correspondingly, in one embodiment, such as... Figure 4 As shown, S100 includes S120 to S160, wherein:

[0082] S120: Gold material is uniformly deposited in the coupling region of the micro / nano fiber substrate, and a gold film layer of preset thickness is obtained by controlling the deposition parameters.

[0083] Specifically, gold material is uniformly deposited in the plane of the coupling region of a micro / nano fiber substrate using thermal evaporation technology. By controlling evaporation parameters such as evaporation time and current, a gold film layer of the desired preset thickness can be obtained. The preset thickness of the gold film layer can be calculated in advance based on theoretical methods. Specifically, this can be achieved by first constructing an equivalent circuit of the electro-optic modulator based on the structure of the parallel electrode plates, and then calculating the operating frequency of the electro-optic modulator based on theoretical analysis. Next, the initial structural dimensions of the electrode plates are designed in conjunction with the high-frequency operating characteristics of the system, and a circuit cascade model is established using software such as SPICE. Then, the initial structural dimensions are successively optimized using simulation results to obtain the target structural dimensions of the parallel plate electrodes. The target structural dimensions include the thickness, width, and length of the parallel plate electrodes, as well as parameters such as the spacing between the two parallel plate electrodes.

[0084] S140: The middle region of the gold film layer is removed by focused ion beam micro / nano fabrication, and opposing positive and negative gold parallel plate electrodes are etched. Specifically, based on the target structural dimensions of the parallel plate electrodes obtained from the above analysis, the middle region of the gold film layer is removed by focused ion beam micro / nano fabrication, and the entire gold film layer is separated to obtain two opposing gold parallel plate electrodes.

[0085] S160: Gold wire leads are welded to the positive and negative gold parallel plate electrodes using a femtosecond laser welding method to obtain opposing positive and negative tuning electrode plates. Specifically, two gold wire leads are precisely welded to the positive and negative gold parallel plate electrodes using high-frequency femtosecond laser welding technology. The positive and negative gold parallel plate electrodes can then be connected to the positive and negative terminals of an external power supply via the gold wire leads to obtain an electric field generated by the power supply that modulates the coupled resonance peak.

[0086] In this embodiment, by rationally designing the size and placement of the positive and negative tuning electrodes, the lithium niobate nanowires can achieve the fastest effective refractive index modulation, thereby improving the response speed of the electro-optic modulator.

[0087] In one embodiment, such as Figure 5 As shown, S600 includes the following S620 to S640, wherein:

[0088] S620: The coupling region of a micro / nano fiber substrate with an adsorbed electro-optic waveguide is filled with aerogel and cured by ultraviolet light. Specifically, a low-refractive-index aerogel is first filled from above the electro-optic waveguide and then cured by ultraviolet light irradiation, thereby achieving a simple encapsulation of the electro-optic modulator.

[0089] S640: An electro-optic modulator is obtained by enhancing the packaging using microwave packaging technology for optoelectronic devices. Further utilizing mature high-speed optoelectronic device microwave packaging technology, the simply packaged electro-optic modulator is enhanced to complete the packaging of the all-fiber electro-optic modulator, preparing for subsequent performance testing.

[0090] Based on the same inventive concept, this application also provides an electro-optic modulator prepared by the above-described method for preparing an electro-optic modulator. The solution provided by this electro-optic modulator is similar to the solution described in the above method. Therefore, the specific limitations of one or more electro-optic modulator embodiments provided below can be found in the limitations of the preparation method for the electro-optic modulator described above, and will not be repeated here.

[0091] In one embodiment, an electro-optic modulator is provided, including a micro / nano fiber substrate, positive and negative tuning electrode plates, and an electro-optic waveguide. The positive and negative tuning electrode plates are disposed in the coupling region of the micro / nano fiber substrate, and the electro-optic waveguide is adsorbed along the axial direction of the micro / nano fiber substrate in the coupling region of the micro / nano fiber substrate and is located between the positive and negative tuning electrode plates.

[0092] Specifically, the micro-nano fiber substrate is the base element of the electro-optic modulator. The coupling region it contains is a micro-nano fiber segment with a diameter ranging from micrometers to nanometers and a constant size. Electro-optic waveguides and positive and negative tuning electrodes that apply voltage to the electro-optic waveguides to generate electro-optic effects are set in this region. As the base of the electro-optic modulator, it is conducive to the occurrence of waveguide directional coupling effect, thereby realizing the intensity modulation of broadband optical signals.

[0093] Furthermore, the electro-optic waveguide is a component that forms a parallel waveguide coupling structure with the micro / nano fiber substrate. When an optical signal passes through the micro / nano fiber substrate, a waveguide-oriented coupling effect will occur at wavelengths where the effective refractive indices of both are equal. This causes the light at that wavelength in the core of the micro / nano fiber substrate to be coupled to the electro-optic waveguide and radiated out, thus forming a loss band in the output spectrum of the micro / nano fiber substrate. Furthermore, due to the electro-optic effect of the material of the electro-optic waveguide, when a voltage is applied to the electro-optic waveguide, such as... Figure 6 As shown, its effective refractive index changes with the applied electric field between the positive and negative tuning electrodes, causing a shift in the coupling wavelength on the transmission spectrum and achieving modulation of the light intensity at the directional coupling wavelength. By applying different voltage signals between the positive and negative tuning electrodes, various forms of intensity modulation of the input optical signal within the micro / nano fiber substrate can be achieved. The materials used to fabricate the electro-optic waveguide are not unique; they can be lithium niobate, KDP-potassium dihydrogen phosphate, gallium arsenide, or cadmium telluride, etc., without limitation. Based on this, the electro-optic waveguide needs to be adsorbed along the axial direction of the micro / nano fiber substrate onto the coupling region of the micro / nano fiber substrate, thereby forming a parallel waveguide coupling structure with the micro / nano fiber substrate.

[0094] It is understood that electro-optic waveguides can also be fabricated using micro- and nano-scale processes to achieve diameters in the micrometer to nanometer range, thereby matching their dimensions with micro- and nano-fiber substrates to enhance the directional coupling effect of the waveguide. Therefore, in this embodiment, the electro-optic waveguide is a nanowire electro-optic waveguide. Correspondingly, the electro-optic waveguide can be lithium niobate nanowires, KDP-potassium dihydrogen phosphate nanowires, gallium arsenide nanowires, or cadmium telluride nanowires, etc.

[0095] In this embodiment, a high-speed electro-optic modulator based on micro-nano optical fiber and lithium niobate nanowire mode coupling is obtained by using a high-frequency electric field to modulate the refractive index of lithium niobate nanowire through the Pockels effect, thereby achieving high-speed modulation of the coupled light intensity of the micro-nano optical fiber core. This results in a high-speed electro-optic modulator with a significantly reduced insertion loss, while achieving a large extinction ratio, large bandwidth, and low half-wave voltage.

[0096] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0097] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for fabricating an electro-optic modulator, characterized in that, The method includes: Relative positive and negative tuning electrode plates are fabricated in the coupling region of a micro / nano fiber substrate, wherein the micro / nano fiber substrate is drawn based on a transmission fiber. A nanowire electro-optic waveguide is manipulated using a microprobe and placed parallel to the axis of the micro / nano fiber substrate above the coupling region of the micro / nano fiber substrate. This allows the nanowire electro-optic waveguide to be adsorbed onto the coupling region of the micro / nano fiber substrate based on the van der Waals forces between the nanowires, and is located between the positive and negative tuning electrode plates. The nanowire electro-optic waveguide is made of a material with electro-optic effect. The coupling region of the micro / nano fiber substrate with adsorbed nanowire electro-optic waveguides is encapsulated to obtain an electro-optic modulator.

2. The method for fabricating the electro-optic modulator according to claim 1, characterized in that, The nanowire electro-optic waveguide is a lithium niobate nanowire.

3. The method for fabricating the electro-optic modulator according to claim 2, characterized in that, The method further includes: Determine the coupling wavelength of the lithium niobate nanowires; The target design size of the lithium niobate nanowires was obtained based on the coupling wavelength analysis, and the lithium niobate nanowires were fabricated based on the target design size.

4. The method for fabricating the electro-optic modulator according to claim 2, characterized in that, The Z-axis of the lithium niobate nanowire located between the positive and negative tuning electrode plates is consistent with the direction of the electric field generated by the positive and negative tuning electrode plates.

5. The method for fabricating the electro-optic modulator according to claim 1, characterized in that, The transmission optical fiber is a common single-mode optical fiber, a photonic crystal fiber, or a microstructure optical fiber.

6. The method for fabricating the electro-optic modulator according to claim 5, characterized in that, The micro / nano fiber substrate is obtained by drawing transmission optical fibers through cyclic tapering and oxyhydrogen flame melting methods.

7. The method for fabricating the electro-optic modulator according to claim 1, characterized in that, The positive and negative tuning electrode plates are parallel plate electrodes made of gold.

8. The method for fabricating the electro-optic modulator according to claim 7, characterized in that, The fabrication of opposing positive and negative tuning electrode plates in the coupling region of the micro / nano fiber substrate includes: Gold material is uniformly vapor-deposited in the coupling region of the micro / nano fiber substrate, and a gold film layer of a preset thickness is obtained by controlling the vapor deposition parameters. The middle region of the gold film layer is removed by focused ion beam micro-nano processing method, and opposite positive and negative gold parallel plate electrodes are obtained by etching. Gold wires were welded to the positive and negative gold parallel plate electrodes using a femtosecond laser welding method to obtain opposing positive and negative tuning electrode plates.

9. The method for fabricating the electro-optic modulator according to any one of claims 1 to 8, characterized in that, The process of encapsulating the coupling region of the micro / nano fiber substrate to which the nanowire electro-optic waveguide is adsorbed, to obtain an electro-optic modulator, includes: The coupling region of the micro / nano fiber substrate on which the nanowire electro-optic waveguide is adsorbed is filled with aerogel and cured by ultraviolet light. An electro-optic modulator is obtained by strengthening the packaging through microwave packaging technology for optoelectronic devices.

10. An electro-optic modulator, prepared by the method for preparing an electro-optic modulator as described in any one of claims 1 to 9, characterized in that, The device includes a micro / nano fiber substrate, positive and negative tuning electrode plates, and a nanowire electro-optic waveguide. The positive and negative tuning electrode plates are disposed in the coupling region of the micro / nano fiber substrate, and the nanowire electro-optic waveguide is adsorbed onto the coupling region of the micro / nano fiber substrate along the axial direction of the micro / nano fiber substrate and is located between the positive and negative tuning electrode plates.

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