Acousto-optic device

Abstract

The utility model relates to an acousto-optic device, which comprises an acousto-optic medium, and a bottom electrode, a piezoelectric transducer and a surface electrode which are positioned on a first surface of the acousto-optic medium and are sequentially arranged along a first direction deviating from the acousto-optic medium, the surface electrode comprises a working part, a connecting part and a welding part which are sequentially arranged along a second direction parallel to the first surface; the working part has a preset size, and the welding part extends to the first surface along the direction towards the acousto-optic medium; the bottom electrode comprises a groove with an opening opposite to the welding part; the orthographic projection of the working part on the top surface of the piezoelectric transducer is located in the top surface of the piezoelectric transducer right above the bottom electrode, and the orthographic projection of the connecting part on the top surface of the piezoelectric transducer is located in the top surface of the piezoelectric transducer right above the groove. By controlling the size and the relative position of the surface electrode and the bottom electrode, a welding area and a working area are distinguished, the problem that welding is not firm due to the fact that the width of the surface electrode is too narrow is solved, and the contradiction between diffraction efficiency and driving power under the condition is solved.

Description

Technical Field

[0001] This application relates to the field of acousto-optic devices, and in particular to an acousto-optic device. Background Technology

[0002] An acousto-optic device is a device that utilizes the acousto-optic interaction between incident light and ultrasonic waves from a transducer to produce diffracted light. It mainly consists of a top electrode, a bottom electrode, a transducer, a bonding layer, an acousto-optic medium, a matching network, and a high-frequency socket. The electrodes are a crucial component of the acousto-optic device. When an external driving signal is provided, a potential difference is created between the top and bottom electrodes. The piezoelectric transducer then converts electrical energy into mechanical energy, thereby generating ultrasonic waves within the acousto-optic medium.

[0003] In related technologies, increasing the length of the surface electrode or increasing the driving power is often used to improve diffraction efficiency. However, increasing the length of the surface electrode leads to higher costs and greater difficulty in growing the acousto-optic crystal, and also results in an excessively small acoustic divergence angle, causing a mismatch between the optical and acoustic divergence angles, which in turn reduces diffraction efficiency. Increasing the driving power, on the other hand, results in energy waste and product heat generation, affecting performance. Utility Model Content

[0004] Therefore, it is necessary to provide an acousto-optic device that can at least improve the diffraction efficiency of the acousto-optic device, addressing the problems mentioned above in the background art.

[0005] In order to solve the above-mentioned technical problems and other problems, according to some embodiments, one aspect of this application provides an acousto-optic device, including: an acousto-optic medium and a bottom electrode, a piezoelectric transducer, and a top electrode arranged sequentially on a first surface of the acousto-optic medium and in a first direction away from the acousto-optic medium.

[0006] The electrode includes a working part, a connecting part, and a welding part arranged sequentially along a second direction parallel to the first surface; the working part has a preset size, and the welding part extends to the first surface along the direction toward the acousto-optic medium for plating solder joints;

[0007] The bottom electrode includes a groove with an opening opposite to the welding part; wherein, the orthographic projection of the working part on the top surface of the piezoelectric transducer is located within the top surface of the piezoelectric transducer directly above the bottom electrode, and the orthographic projection of the connecting part on the top surface of the piezoelectric transducer is located within the top surface of the piezoelectric transducer directly above the groove.

[0008] In the acousto-optic device described in the above embodiments, by controlling the welding part to be positioned opposite to the groove, short circuits with the bottom electrode are avoided; the working part and welding part of the meter electrode are separated, the width of the working part is preset independently, and the welding part is plated independently, thus overcoming the limitation of the solder joint size and effectively solving the problem of welding failure or weak welding when the width of the meter electrode is smaller than the width of the solder joint.

[0009] In some embodiments, the welding section includes a plurality of surface electrode solder joints;

[0010] The area of ​​the welded part shall not be less than the sum of the areas of the multiple electrode weld points.

[0011] In the above embodiments, the additional redundant design, where the total area of ​​the welded portion is greater than the sum of the minimum required areas of all weld points, ensures that the weld points do not overlap and retains process allowance, thereby improving the fault tolerance rate.

[0012] In some embodiments, the preset dimensions include: a preset length and a preset width;

[0013] The preset length is not greater than the length of the piezoelectric transducer;

[0014] The preset width is not greater than the width of the electrode solder joint.

[0015] The length is used to characterize the dimension along the second direction; the width is used to characterize the dimension along the third direction; the third direction is perpendicular to the first direction and the second direction.

[0016] In the above embodiments, the width of the working part of the dial electrode is reduced, which can improve the diffraction efficiency. At the same time, the welding part and the working part are decoupled, which avoids the dial electrode from being damaged and reduces production costs.

[0017] In some embodiments, the groove extends through the bottom electrode along a first direction;

[0018] The width of the welded part is smaller than the width of the groove.

[0019] In some embodiments, the bottom electrode includes a plurality of bottom electrode solder joints located on the top surface of the bottom electrode away from the surface electrode and the piezoelectric transducer.

[0020] In some embodiments, the preset width is associated with the spot diameter of the incident laser.

[0021] In the above embodiments, the preset width of the working part is reasonably matched with the diameter of the incident laser spot, which can meet the efficiency requirements while greatly reducing the required driving power, reducing the heat generation of the product, and making the product work more stably.

[0022] In some embodiments, the target cross-sectional shape of the electrode is selected from rectangle, circle, ellipse, polygon, rectangle and combinations thereof; the target cross-section is parallel to the second direction and the third direction.

[0023] In some embodiments, the sub-electrode is located within the groove; the sidewall of the sub-electrode is in contact with the sidewall of the weld portion, but not with the bottom electrode.

[0024] In the above embodiment, the sub-electrode is located in the groove of the bottom electrode, which reduces the entry of impurities into the gap during the transducer thinning process without causing a short circuit, thereby reducing the defect rate during the thinning process.

[0025] In some embodiments, the orthographic projection of the bottom electrode onto the first surface lies within the first surface.

[0026] In some embodiments, the matching circuit is configured such that the positive terminal is connected to the bottom electrode solder joint via a positive metal wire, and the negative terminal is connected to the top electrode solder joint via a metal wire.

[0027] The acousto-optic device provided in this application has the following unexpected technical effects:

[0028] In the embodiments provided in this application, the structural design of moving the position of the surface electrode from the center of the piezoelectric transducer to the edge and aligning it with the bottom electrode groove achieves physical decoupling of the surface electrode functional area. The welding part is independently set in the bottom electrode groove area, and its width is not limited by the micro-scale of the working part. While improving diffraction efficiency, it ensures that the solder joint size has sufficient metal pad support area, effectively solving the problem of insufficient solder joint adhesion caused by the narrowing of the electrode width in traditional designs, and reducing the alignment difficulty and operation error rate during manual or automated wire bonding. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0030] Figure 1a This is one of the schematic diagrams of acousto-optic devices related to this technology;

[0031] Figure 1b This is the second schematic diagram of an acousto-optic device related to the technology.

[0032] Figure 2 This is one of the three-dimensional schematic diagrams of the acousto-optic device provided in one embodiment of this application;

[0033] Figure 3 This is a second three-dimensional schematic diagram of the acousto-optic device provided in one embodiment of this application;

[0034] Figure 4 This is one of the top views of the acousto-optic device provided in one embodiment of this application;

[0035] Figure 5 This is a front view schematic diagram of an acousto-optic device provided in one embodiment of this application;

[0036] Figure 6 This is a second top view schematic diagram of the acousto-optic device provided in one embodiment of this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 10. Top electrode; 2. Piezoelectric transducer; 11. Bottom electrode; 4. Acousto-optic medium; 5. Bottom electrode solder joint; 6. Positive metal wire; 7. Top electrode solder joint; 8. Negative metal wire; 12. Working part; 13. Connecting part; 14. Welding part. Detailed Implementation

[0039] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0040] 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 in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0041] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0042] It should be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0043] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a direct connection or an indirect connection through an intermediate medium, or they can refer to the internal connection of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] In the design of acousto-optic devices, diffraction efficiency is one of the important indicators, which can be expressed by the following formula:

[0045]

[0046] Where η is the diffraction efficiency, λ is the wavelength of the incident laser, M2 is the acousto-optic figure of merit of the material (depending on the material itself), and P a Where is the radio frequency power, and L is the acousto-optic interaction length, i.e., the length of the surface electrode. According to the above formula, with the same electrode length L, the diffraction efficiency can be improved by reducing the width H of the surface electrode.

[0047] In related technologies, there are two cases regarding the width of the electrode:

[0048] I. For example Figure 1a As shown, when the width H1 of the surface electrode 10 is greater than the diameter of the surface electrode solder joint 7, the welding difficulty is not high.

[0049] II. Figure 1b As shown, when the width H2 of the electrode 10 is smaller than the diameter of the electrode solder joint 7, the electrode solder joint 7 contacts the piezoelectric transducer 2, effectively increasing the electrode width H2 and causing a decrease in diffraction efficiency η. Due to the different materials in contact, the solder joint has a lower degree of strength, and the metal wire solder joint is prone to incomplete soldering or detachment, creating potential hazards. In addition, since ultrasonic wire bonding machines require a certain area of ​​metal pads to support the solder joint, the narrow electrode makes it impossible for the limited load-bearing area to meet the anchoring conditions required for metallurgical bonding and atomic diffusion of the solder joint, resulting in interface peeling failure of the electrode solder joint 7.

[0050] Therefore, how to reduce the impact on welding while improving diffraction efficiency by reducing the width of the surface electrode has become one of the problems that researchers in this field urgently need to solve.

[0051] Based on this, please refer to Figure 2 This application provides an acousto-optic device, comprising: an acousto-optic medium 4 and a bottom electrode 11, a piezoelectric transducer 2, and a top electrode 10 arranged sequentially on a first surface of the acousto-optic medium 4 and in a first direction away from the acousto-optic medium.

[0052] The electrode 10 includes a working part 12, a connecting part 13, and a welding part 14 arranged sequentially along a second direction parallel to the first surface; the working part 12 has a preset size, and the welding part 14 extends to the first surface along the direction toward the acousto-optic medium 4 for plating solder joints.

[0053] The bottom electrode 11 includes a groove with an opening opposite to the welding part 14; wherein, the orthographic projection of the working part 12 on the top surface of the piezoelectric transducer 2 is located within the top surface of the piezoelectric transducer 2 directly above the bottom electrode 11, and the orthographic projection of the connecting part 13 on the top surface of the piezoelectric transducer 2 is located within the top surface of the piezoelectric transducer 2 directly above the groove.

[0054] The materials of the electrode 10 include, but are not limited to, gold (Au), silver (Ag), aluminum (Al), etc.

[0055] The materials of the bottom electrode 11 include, but are not limited to, gold (Au), silver (Ag), aluminum (Al), etc.

[0056] For example, the piezoelectric transducer 2 can be formed by stacking multiple layers of piezoelectric materials of different thicknesses in sequence, without any limitation.

[0057] Furthermore, in an optional embodiment, the welding portion 14 includes a plurality of surface electrode solder joints 7. The orthographic projection of the bottom electrode 11 onto the first surface lies within the first surface. The bottom electrode 11 includes a plurality of bottom electrode solder joints 5, which are located on the side of the top surface of the bottom electrode 11 away from the surface electrode 10 and the piezoelectric transducer 2.

[0058] The diameter of the solder joints ranges from 60μm to 120μm.

[0059] As an example, the solder joint diameter can be 60μm, 80μm, 100μm or 120μm, etc.

[0060] The target cross-sectional shape of the electrode 10 is selected from rectangle, circle, ellipse, polygon, rectangle and combination thereof;

[0061] For example, please refer to Figure 4 The rectangular area is located on the piezoelectric transducer 2, the circular area is located on the acousto-optic medium 4, and the area of ​​the welded part 14 is not less than the sum of the areas of the multiple surface electrode weld points 7.

[0062] For ease of understanding, in this embodiment, the acousto-optic medium may include a first surface located on the front side and a back surface, i.e., a second surface, opposite to the front side. Ignoring the flatness of the first and second surfaces, a direction away from the acousto-optic medium is defined as the first direction, and directions parallel to the first surface include the second direction and a third direction. For example, the arrangement direction of the working part 12, the connecting part 13, and the welding part 14 is the second direction, and the plane containing the acousto-optic medium 4 can be determined based on the second direction and the third direction. The first direction, the second direction, and the third direction can be mutually perpendicular. In this embodiment, the first direction is defined as the Z-axis direction, the second direction as the Y-axis direction, and the third direction as the X-axis direction.

[0063] Please see Figure 3 , Figure 4 and Figure 5 , Figure 3 This is a second three-dimensional schematic diagram of the acousto-optic device provided in one embodiment of this application. Figure 4 This is a top view schematic diagram of an acousto-optic device provided in one embodiment of this application. Figure 5 This is a front view schematic diagram of an acousto-optic device provided in one embodiment of this application. For better illustration, the piezoelectric transducer 2 is converted into a transparent view, retaining only the outer outline.

[0064] In the above embodiment, the processing steps are consistent with existing solutions: bottom electrode plating – piezoelectric transducer pressure welding – transducer thinning – top electrode plating. The difference lies in modifying the shape of the bottom electrode 11 to include a notch (groove), and simultaneously moving the position of the top electrode 10 from the center of the piezoelectric transducer 2 to its edge, placing it at the center of the groove in the bottom electrode 11. At this point, the welding portion 14 is isolated from the bottom electrode 11 by the groove, eliminating the risk of short circuits during welding. A separate welding portion 14 is pre-set for plating the top electrode solder joint 7, ensuring welding reliability.

[0065] Furthermore, the preset dimensions include: a preset length L3 and a preset width H3; the preset length L3 is not greater than the length of the piezoelectric transducer 2; the preset width H3 is not greater than the width of the electrode solder joint 7, specifically as follows: Figure 4 As shown.

[0066] The length is used to characterize the dimension along the second direction (OY direction); the width is used to characterize the dimension along the third direction (OX direction). For ease of understanding, the OZ direction is used to replace the first direction, the OY direction to replace the second direction, and the OX direction to replace the third direction.

[0067] In addition, the groove extends through the bottom electrode 11 along the first direction, and the width of the welding part 14 is smaller than the width of the groove.

[0068] Here, as Figure 5 As shown, the right side of the working part 12 coincides with the left side of the groove, the welding part 14 is located on the first surface of the acousto-optic medium 4, and the connecting part 13 connects the working part 12 and the welding part 14.

[0069] According to the energy conversion mechanism of piezoelectric transducers, the mutual conversion of electrical energy and mechanical energy can only be achieved when the top electrode 10, the piezoelectric material, and the bottom electrode 11 form a spatially geometrically overlapping region, ultimately exciting an ultrasonic field. For example... Figure 4 and Figure 5As shown, in the above embodiment, due to the presence of the groove in the bottom electrode 11, the final effective electrode area is determined by the geometric parameters of the working part 12, with an effective length of L3 and an effective width of H3. The connecting part 13 does not have a corresponding bottom electrode 11, therefore no sound field is generated at the location of the connecting part 13. Similarly, the welding part 14 has a width smaller than the width of the groove and does not contact the bottom electrode 11, serving only as a welding working area.

[0070] In addition, the actual effective working part 12 dimensions (preset width H3, preset length L3) can be freely controlled according to actual needs.

[0071] The preset width H3 is related to the diameter of the incident laser spot. When the diameter of the incident laser is at the μm level, an excessively large electrode width will cause a waste of driving power. The preset width of the working part 12 is reasonably matched with the spot diameter and is also reduced to the μm level. While meeting the efficiency requirements, it directly reduces the heat generated by the device, suppresses problems such as sound velocity drift and material thermal deformation caused by temperature rise, and improves the working stability.

[0072] The preset length L3 must satisfy the relationship that the acoustic divergence angle and the optical divergence angle are approximately α≈1. The specific formula is shown below:

[0073]

[0074] in, Let θ be the light divergence angle, and Δθ be the sound divergence angle. The sound divergence angle can be expressed as:

[0075] Where, λ a The wavelength of the sound at the operating frequency is given. When the wavelength is constant, the longer the preset length L3, the smaller the acoustic divergence angle. If the acoustic divergence angle is greater than the optical divergence angle, the acoustic energy in the edge region of the ultrasonic beam cannot participate in the interaction because it exceeds the beam's coverage area, resulting in acoustic energy redundancy loss. If the optical divergence angle is greater than the acoustic divergence angle, the edge rays lack the interaction of ultrasonic waves in the same propagation direction, failing to meet the Bragg diffraction condition, causing a decrease in light energy utilization and leading to a reduction in diffraction efficiency. Therefore, the selection of the preset length L3 requires comprehensive consideration.

[0076] In an optional embodiment, the acousto-optic device further includes: a sub-electrode 15 located within the groove; the sidewall of the sub-electrode is in contact with the sidewall of the welding portion, but not with the bottom electrode.

[0077] Specifically, based on the aforementioned notch (groove) design of the bottom electrode 11, a sub-electrode 15 is introduced into the notch portion. Although the sub-electrode 15 is connected to the welding portion 14 of the top electrode 10, an insulating gap exists between it and the bottom electrode 11 to ensure that they do not form an electrical path, thus avoiding the risk of short circuits. In the transducer thinning process, the sub-electrode 15 fills the groove space, forming a physical barrier that effectively prevents impurities such as grinding particles and chemical solutions from intruding into the notch area during the thinning process, thereby improving process reliability.

[0078] Furthermore, in some embodiments, the acousto-optic device further includes:

[0079] The matching circuit (not shown) is configured such that the positive electrode is connected to the surface electrode solder joint 7 via the positive electrode metal wire 8, and the negative electrode is connected to the bottom electrode solder joint 5 via the negative electrode metal wire 6. When an external driving signal is provided, a potential difference is formed between the surface electrode 10 and the bottom electrode 11, and the piezoelectric transducer 2 performs electro-mechanical energy conversion, thereby generating ultrasonic waves inside the acousto-optic medium 4.

[0080] The diameter of the metal wire ranges from 20μm to 50μm, such as 20μm, 30μm, 40μm or 50μm.

[0081] The acousto-optic device provided in this application has the following unexpected technical effects:

[0082] By introducing a groove within the bottom electrode and shifting the electrode plating position, the working part and welding part of the electrode are separated, decoupling the electrode size and function. The independent welding part effectively solves the problem of inability to weld or weak welding when the electrode width is reduced to below the weld point size, preventing electrode damage due to subsequent weld point detachment and reducing production costs. Furthermore, by freely controlling the effective preset width and length of the actual working part according to actual needs, the electro-mechanical energy conversion can be concentrated in the area matching the incident laser spot, meeting usage requirements while reducing the overall driving power required by the acousto-optic device.

[0083] In addition, the acousto-optic device provided in this application embodiment is compatible with the original processing technology. Without adding extra process steps, this structure effectively reduces the welding difficulty and achieves a performance breakthrough.

[0084] Please note that the above embodiments are for illustrative purposes only and do not imply any limitation on the present invention.

[0085] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0086] 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.

[0087] The above embodiments merely illustrate 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 patent application. 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. An acousto-optic device, characterized in that, include: An acousto-optic medium and a bottom electrode, a piezoelectric transducer, and a surface electrode arranged sequentially on a first surface of the acousto-optic medium along a first direction away from the acousto-optic medium; The electrode includes a working part, a connecting part, and a welding part arranged sequentially along a second direction parallel to the first surface; the working part has a preset size, and the welding part extends to the first surface along the direction toward the acousto-optic medium for plating solder joints; The bottom electrode includes a groove with an opening opposite to the welding part; wherein, the orthographic projection of the working part on the top surface of the piezoelectric transducer is located within the top surface of the piezoelectric transducer directly above the bottom electrode, and the orthographic projection of the connecting part on the top surface of the piezoelectric transducer is located within the top surface of the piezoelectric transducer directly above the groove.

2. The acousto-optic device according to claim 1, characterized in that, The welding section includes multiple surface electrode solder joints; The area of ​​the welded part is not less than the sum of the areas of the plurality of surface electrode weld points.

3. The acousto-optic device according to claim 2, characterized in that, The preset dimensions include: preset length and preset width; The preset length is not greater than the length of the piezoelectric transducer; The preset width is not greater than the width of the electrode solder joint; Wherein, the length is used to characterize the dimension along the second direction; the width is used to characterize the dimension along the third direction; the third direction is perpendicular to the first direction and the second direction.

4. The acousto-optic device according to claim 2, characterized in that, The groove extends through the bottom electrode along the first direction; The width of the welded portion is smaller than the width of the groove.

5. The acousto-optic device according to claim 2, characterized in that, The bottom electrode includes multiple bottom electrode solder joints, which are located on the top surface of the bottom electrode away from the surface electrode and the piezoelectric transducer.

6. The acousto-optic device according to claim 3, characterized in that, The preset width is related to the diameter of the incident laser spot.

7. The acousto-optic device according to claim 3, characterized in that, The target cross-sectional shape of the electrode is selected from rectangle, circle, ellipse, polygon, rectangle and combination thereof; the target cross-section is parallel to the second direction and the third direction.

8. The acousto-optic device according to any one of claims 1-5, characterized in that, Also includes: The sub-electrode is located within the groove; the sidewall of the sub-electrode is in contact with the sidewall of the welding part, but not with the bottom electrode.

9. The acousto-optic device according to any one of claims 1-5, characterized in that, The orthographic projection of the bottom electrode onto the first surface lies within the first surface.

10. The acousto-optic device according to claim 6, characterized in that, Also includes: The matching circuit is configured such that the positive terminal is connected to the bottom electrode solder joint via a positive metal wire, and the negative terminal is connected to the top electrode solder joint via a metal wire.

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