阅读说明：本技术 一种磁光隔离器芯及其制作方法、磁光隔离器 (Magneto-optical isolator core, manufacturing method thereof and magneto-optical isolator ) 是由 郑熠 吴少凡 王帅华 黄鑫 徐刘伟 于 2019-10-08 设计创作，主要内容包括：本发明公开了一种磁光隔离器芯及其制作方法、磁光隔离器,属于光纤通讯技术领域,能够解决现有磁光隔离器插入损耗较大,封装成品率较低的问题。所述磁光隔离器芯包括中空柱状的磁环和柱状的磁光晶体；磁环的内壁上设置有第一焊接金属层；磁光晶体的外壁上设置有第二焊接金属层,磁环的内径小于磁光晶体的外径,磁环在经过降温冷缩后可套设在磁光晶体上,以使第一焊接金属层和第二焊接金属层在磁环温度回升后压焊连接。本发明用于制作磁光隔离器芯。(The invention discloses a magneto-optical isolator core, a manufacturing method thereof and a magneto-optical isolator, belongs to the technical field of optical fiber communication, and can solve the problems of large insertion loss and low packaging yield of the existing magneto-optical isolator. The magneto-optical isolator core comprises a hollow columnar magnetic ring and a columnar magneto-optical crystal; a first welding metal layer is arranged on the inner wall of the magnetic ring; the outer wall of the magneto-optical crystal is provided with a second welding metal layer, the inner diameter of the magnetic ring is smaller than the outer diameter of the magneto-optical crystal, and the magnetic ring can be sleeved on the magneto-optical crystal after being cooled and shrunk, so that the first welding metal layer and the second welding metal layer are connected in a pressure welding mode after the temperature of the magnetic ring rises. The invention is used for manufacturing the magneto-optical isolator core.)

1. A magneto-optical isolator core is characterized by comprising a hollow columnar magnetic ring and a columnar magneto-optical crystal;

a first welding metal layer is arranged on the inner wall of the magnetic ring; the magneto-optical crystal is characterized in that a second welding metal layer is arranged on the outer wall of the magneto-optical crystal, the inner diameter of the magnetic ring is smaller than the outer diameter of the magneto-optical crystal, and the magnetic ring can be sleeved on the magneto-optical crystal after being cooled and shrunk, so that the first welding metal layer and the second welding metal layer are connected in a pressure welding mode after the temperature of the magnetic ring rises.

2. A magneto-optical isolator core as claimed in claim 1, wherein a connecting metal layer is further provided between the inner wall of the magnetic ring and the first weld metal layer; the connecting metal layer is used for connecting the first welding metal layer with the inner wall of the magnetic ring.

3. A magneto-optical isolator core according to claim 1 or 2, further comprising a first wedge plate, a second wedge plate, a first support bracket and a second support bracket;

a first mounting groove is formed in one end face of the magnetic ring, and the first wedge angle piece can be assembled in the first mounting groove; the first support frame is provided with a first protruding structure in the center, and the first protruding structure is used for being matched with the first wedge angle piece to fill the first installation groove;

a second mounting groove is formed in the other end face of the magnetic ring, and the second wedge angle piece can be assembled in the second mounting groove; the center of the second support frame is provided with a second protruding structure, and the second protruding structure is used for being matched with the second wedge angle piece to fill the second mounting groove.

4. A magneto-optical isolator core according to claim 3, further comprising a cylindrical housing having one open end, and an end cap for closing the housing opening;

the magnetic ring, the magneto-optical crystal, the first wedge angle piece, the second wedge angle piece, the first support frame and the second support frame are all assembled in the shell, the first support frame abuts against the bottom surface of the shell, and the second support frame abuts against the end cover.

5. A magneto-optical isolator core according to claim 4, wherein the housing, the end cap, the first support bracket and the second support bracket each have a central bore coaxial with the magneto-optical crystal, the central bore having an aperture larger than an outer diameter of the magneto-optical crystal.

6. A magneto-optical isolator core according to claim 2, wherein said first solder metal layer and said second solder metal layer are both gold layers and said connecting metal layer is a copper layer.

7. A magneto-optical isolator core as claimed in claim 2 or 6, wherein said connection metal layer is formed on an inner wall of said magnetic ring by an electroplating process; the first welding metal layer is manufactured on the connecting metal layer through an electroplating process;

the second welding metal layer is manufactured on the outer wall of the magneto-optical crystal through an ion sputtering process.

8. A method of making a magneto-optical isolator core as claimed in any one of claims 1 to 7, said method comprising:

manufacturing the first welding metal layer on the inner wall of the magnetic ring, and manufacturing the second welding metal layer on the outer wall of the magneto-optical crystal;

cooling the magnetic ring to a first preset temperature so that the magnetic ring can be sleeved on the magneto-optical crystal;

sleeving the magnetic ring on the magneto-optical crystal, and heating the magnetic ring to enable the first welding metal layer and the second welding metal layer to be connected in a laminating welding mode, so that the magneto-optical isolator core is obtained.

9. The method as claimed in claim 8, wherein before the step of forming the first weld metal layer on the inner wall of the magnetic ring, the method further comprises:

manufacturing a connecting metal layer on the inner wall of the magnetic ring; the connecting metal layer is used for connecting the first welding metal layer with the inner wall of the magnetic ring.

10. A magneto-optical isolator comprising the magneto-optical isolator core according to any one of claims 1 to 7.

Technical Field

The invention relates to a magneto-optical isolator core, a manufacturing method thereof and a magneto-optical isolator, and belongs to the technical field of optical fiber communication.

Background

In recent years, with the development of optical fiber communication technology, a magneto-optical device utilizing interaction between light and magnetism has been attracting attention, and a magneto-optical isolator is a magneto-optical device applied to the field of communication. The magneto-optical isolator is also called as optical isolator, and is an optically passive device with nonreciprocal transmission, which has low insertion loss to forward transmission light and has great attenuation to reverse transmission light. Since the magneto-optical isolator allows light to pass in one direction only and blocks light from passing in the opposite direction, light reflected by the optical fiber echo can be well isolated by the magneto-optical isolator, which makes the magneto-optical isolator an essential optical component in high-speed or long-distance optical fiber communications.

The existing magneto-optical isolator is based on the non-reciprocity of the faraday effect, and generally comprises a faraday rotor consisting of a magnetic ring and a magneto-optical crystal, wedge-shaped sheets respectively arranged on the light inlet side and the light outlet side of the faraday rotor, and the like. In the manufacturing process of the existing magneto-optical isolator, the magnetic ring and the magneto-optical crystal and the magnetic ring and the wedge angle sheet are generally bonded by glue, however, the glue can penetrate into the light passing surface of the magneto-optical crystal during bonding to pollute the light passing surface, so that the insertion loss of the magneto-optical isolator is large, and the packaging yield is low.

Disclosure of Invention

The invention provides a magneto-optical isolator core, a manufacturing method thereof and a magneto-optical isolator, which can solve the problems of large insertion loss and low packaging yield of the existing magneto-optical isolator.

The invention provides a magneto-optical isolator core, which comprises a hollow columnar magnetic ring and a columnar magneto-optical crystal; a first welding metal layer is arranged on the inner wall of the magnetic ring; the magneto-optical crystal is characterized in that a second welding metal layer is arranged on the outer wall of the magneto-optical crystal, the inner diameter of the magnetic ring is smaller than the outer diameter of the magneto-optical crystal, and the magnetic ring can be sleeved on the magneto-optical crystal after being cooled and shrunk, so that the first welding metal layer and the second welding metal layer are connected in a pressure welding mode after the temperature of the magnetic ring rises.

Optionally, a connection metal layer is further disposed between the inner wall of the magnetic ring and the first welding metal layer; the connecting metal layer is used for connecting the first welding metal layer with the inner wall of the magnetic ring.

Optionally, the magneto-optical isolator core further comprises a first wedge plate, a second wedge plate, a first support frame and a second support frame; a first mounting groove is formed in one end face of the magnetic ring, and the first wedge angle piece can be assembled in the first mounting groove; the first support frame is provided with a first protruding structure in the center, and the first protruding structure is used for being matched with the first wedge angle piece to fill the first installation groove; a second mounting groove is formed in the other end face of the magnetic ring, and the second wedge angle piece can be assembled in the second mounting groove; the center of the second support frame is provided with a second protruding structure, and the second protruding structure is used for being matched with the second wedge angle piece to fill the second mounting groove.

Optionally, the magneto-optical isolator core further comprises a cylindrical shell with an opening at one end, and an end cover for closing the opening of the shell; the magnetic ring, the magneto-optical crystal, the first wedge angle piece, the second wedge angle piece, the first support frame and the second support frame are all assembled in the shell, the first support frame abuts against the bottom surface of the shell, and the second support frame abuts against the end cover.

Optionally, the housing, the end cap, the first support frame and the second support frame all have a central hole coaxial with the magneto-optical crystal, and an aperture of the central hole is larger than an outer diameter of the magneto-optical crystal.

Optionally, the first welding metal layer and the second welding metal layer are both gold layers, and the connection metal layer is a copper layer.

Optionally, the connection metal layer is manufactured on the inner wall of the magnetic ring through an electroplating process; the first welding metal layer is manufactured on the connecting metal layer through an electroplating process; the second welding metal layer is manufactured on the outer wall of the magneto-optical crystal through an ion sputtering process.

The invention also provides a manufacturing method applied to any one of the magneto-optical isolator cores, which comprises the following steps: manufacturing the first welding metal layer on the inner wall of the magnetic ring, and manufacturing the second welding metal layer on the outer wall of the magneto-optical crystal; cooling the magnetic ring to a first preset temperature so that the magnetic ring can be sleeved on the magneto-optical crystal; sleeving the magnetic ring on the magneto-optical crystal, and heating the magnetic ring to enable the first welding metal layer and the second welding metal layer to be connected in a laminating welding mode, so that the magneto-optical isolator core is obtained.

Optionally, before the first welding metal layer is fabricated on the inner wall of the magnetic ring, the method further includes: manufacturing a connecting metal layer on the inner wall of the magnetic ring; the connecting metal layer is used for connecting the first welding metal layer with the inner wall of the magnetic ring.

The invention also provides a magneto-optical isolator comprising any one of the magneto-optical isolator cores.

The invention can produce the beneficial effects that:

1) according to the magneto-optical isolator core provided by the invention, the first welding metal layer is arranged on the inner wall of the magnetic ring, the second welding metal layer is arranged on the outer wall of the magneto-optical crystal, and the magnetic ring is cooled by utilizing the principle of expansion with heat and contraction with cold so that the inner diameter of the magnetic ring is increased after the magnetic ring is contracted, so that the magneto-optical crystal can be assembled in an axial hole of the magnetic ring, then the magnetic ring expands after the temperature rises, the inner diameter of the magnetic ring is decreased, and the second welding metal layer on the outer wall of the magneto-optical crystal assembled in the magnetic ring and the first welding metal layer on the inner wall of the magnetic ring are connected by pressure welding under the extrusion of the expansion force of the magnetic. Compared with the prior art in which connection is performed through glue, the low-temperature pressure welding connection in the invention can enable connection between the magnetic ring and the magneto-optical crystal to be firmer, and meanwhile, glue is prevented from polluting the light passing surface of the magneto-optical crystal, so that the insertion loss of the magneto-optical isolator is reduced, and the packaging yield of the magneto-optical isolator is improved.

2) According to the magneto-optical isolator core provided by the invention, the first mounting groove and the second mounting groove are respectively arranged on the two end faces of the magnetic ring, the first wedge angle sheet is assembled into the first mounting groove, and the first support frame is used for fixing the position of the first wedge angle sheet; assembling the second wedge angle piece into a second mounting groove, and fixing the position of the second wedge angle piece by using a second support frame; compared with the prior art that the connection is carried out through glue, the position of the wedge angle piece is limited in the gap between the mounting groove and the support frame, so that the position of the wedge angle piece is fixed, glue is not needed between the wedge angle piece and the magnetic ring, the glue is prevented from polluting the light passing surface of the magneto-optical crystal, the insertion loss of the magneto-optical isolator is further reduced, and the packaging yield of the magneto-optical isolator is improved.

3) The magneto-optical isolator provided by the invention realizes the connection of the magnetic ring and the magneto-optical crystal through a low-temperature welding technology, and realizes the position fixation of the wedge angle piece through the matching of the mounting groove and the support frame. Therefore, glue is not needed in the whole assembly process of the core of the magneto-optical isolator, and the problems of large insertion loss and low packaging yield of the magneto-optical isolator caused by the fact that glue pollutes the light passing surface of the magneto-optical crystal are completely avoided.

Drawings

FIG. 1 is a schematic diagram of a magneto-optical isolator core structure according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for manufacturing a magneto-optical isolator core according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

The embodiment of the invention provides a magneto-optical isolator core, which comprises a hollow columnar magnetic ring 11 and a columnar magneto-optical crystal 12, as shown in figure 1; a first welding metal layer is arranged on the inner wall of the magnetic ring 11; the outer wall of the magneto-optical crystal 12 is provided with a second welding metal layer, the inner diameter of the magnetic ring 11 is smaller than the outer diameter of the magneto-optical crystal 12, and the magnetic ring 11 can be sleeved on the magneto-optical crystal 12 after being cooled and shrunk, so that the first welding metal layer and the second welding metal layer are connected in a pressure welding mode after the temperature of the magnetic ring 11 rises.

The magnetic ring 11 is generally a permanent magnet magnetic ring, and the permanent magnet may be any one of ferrite, a nickel-cobalt magnet, a samarium-cobalt magnet, or a neodymium magnet, which is not limited in this embodiment of the present invention. Referring to fig. 1, the magnetic ring 11 is a cylindrical structure with a central hole. The inner wall of the magnetic ring 11 is provided with a first welding metal layer, which may be a gold layer, and since the gold layer is difficult to be directly fabricated on the inner wall of the magnetic ring 11, a connection metal layer may be disposed between the inner wall of the magnetic ring 11 and the first welding metal layer, the first welding metal layer is connected with the inner wall of the magnetic ring 11 by using the connection metal layer, which may be a copper layer. Specifically, a copper layer may be first manufactured on the inner wall of the magnetic ring 11 by using an electroplating process, the thickness of the copper layer may be controlled to be between 1 μm and 2 μm, and then a gold layer may be manufactured on the copper layer by using an electroplating process, and the thickness of the gold layer may be controlled to be between 1 μm and 2 μm.

Referring to fig. 1, the magneto-optical crystal 12 is generally cylindrical and has a shape corresponding to the axial hole of the magnetic ring 11, and the outer diameter of the magneto-optical crystal 12 is slightly larger than the inner diameter of the magnetic ring 11. A second welding metal layer, which may be a gold layer, is disposed on the outer wall of the magneto-optical crystal 12. Specifically, a gold layer can be manufactured on the outer wall of the magneto-optical crystal 12 by using an ion sputtering process, and the thickness of the gold layer can be controlled to be between 0.1 μm and 0.22 μm.

When the magnetic ring 11 and the magneto-optical crystal 12 are assembled, the temperature of the magnetic ring 11 can be cooled to-30 ℃ by using a cooling box, then the magnetic ring is placed in a liquid nitrogen cooling device, the flow rate of liquid nitrogen is controlled to enable the magnet 11 to be cooled to-120 ℃ at a constant speed, and the cooling time is about 10 minutes. The magnetic ring 11 shrinks after being cooled, the inner diameter increases, and the outer diameter of the magneto-optical crystal 12 is matched with the inner diameter of the magnetic ring 11, so that the magneto-optical crystal 12 can be assembled in the axial hole of the magnetic ring 11. When the temperature of the magnetic ring 11 rises, the magnetic ring expands, the inner diameter of the magnetic ring becomes smaller, so that the gold layer on the outer wall of the magneto-optical crystal 12 assembled in the magnetic ring 11 and the gold layer on the inner wall of the magnetic ring 11 are connected by pressure welding under the extrusion of the expansion force of the magnetic ring 11 to form a welding layer 13, thereby realizing the tight welding of the magnetic ring 11 and the magneto-optical crystal 12, and further finishing the fixation of the magneto-optical crystal 12. In practical application, before the magneto-optical crystal 12 is installed in the magnetic ring 11, the magneto-optical crystal 12 can be cooled to-30 ℃ by using a cooling box and then installed in the axial hole of the magnetic ring 11.

According to the magneto-optical isolator core provided by the invention, the first welding metal layer is arranged on the inner wall of the magnetic ring, the second welding metal layer is arranged on the outer wall of the magneto-optical crystal, and the magnetic ring is cooled by utilizing the principle of expansion with heat and contraction with cold so that the inner diameter of the magnetic ring is increased after the magnetic ring is contracted, so that the magneto-optical crystal can be assembled in an axial hole of the magnetic ring, then the magnetic ring expands after the temperature rises, the inner diameter of the magnetic ring is decreased, and the second welding metal layer on the outer wall of the magneto-optical crystal assembled in the magnetic ring and the first welding metal layer on the inner wall of the magnetic ring are connected by pressure welding under the extrusion of the expansion force of the magnetic. Compared with the prior art in which connection is performed through glue, the low-temperature pressure welding connection in the invention can enable connection between the magnetic ring and the magneto-optical crystal to be firmer, and meanwhile, glue is prevented from polluting the light passing surface of the magneto-optical crystal, so that the insertion loss of the magneto-optical isolator is reduced, and the packaging yield of the magneto-optical isolator is improved.

Further, referring to fig. 1, the magneto-optical isolator core further includes a first wedge plate 14, a second wedge plate 15, a first support frame 16 and a second support frame 17; a first mounting groove 18 is formed in one end face of the magnetic ring 11, and the first wedge piece 14 can be assembled in the first mounting groove 18; the first support frame 16 has a first raised structure in the center, and the first raised structure is used for matching with the first wedge piece 14 to fill the first mounting groove 18; a second mounting groove 19 is formed in the other end face of the magnetic ring 11, and the second wedge piece 15 can be assembled in the second mounting groove 19; the second supporting frame 17 has a second protruding structure at the center thereof for cooperating with the second wedge 15 to fill the second mounting groove 19.

Referring to fig. 1, the first support frame 16 is a circular plate with a central protrusion structure, and the shape of the protrusion structure is fitted with the first wedge piece 14, so as to ensure that a cavity formed between the first support frame 16 and the magnetic ring 11 can just accommodate the first wedge piece 14 after the assembly is completed; the second support frame 17 is also a circular plate with a central protruding structure, and the shape of the protruding structure is attached to the second wedge piece 15, so that a cavity formed between the second support frame 17 and the magnetic ring 11 can just contain the second wedge piece 15 after the assembly is completed.

According to the magneto-optical isolator core provided by the invention, the first mounting groove 18 and the second mounting groove 19 are respectively arranged on the two end faces of the magnetic ring 11, the first wedge piece 14 is assembled into the first mounting groove 18, and the first support frame 16 is used for fixing the position of the first wedge piece 14; fitting the second wedge piece 15 into the second mounting groove 19, and fixing the position of the second wedge piece 15 using the second support bracket 17; compared with the prior art that the connection is carried out through glue, the position of the wedge angle piece is limited in the gap between the installation groove and the support frame, so that the position of the wedge angle piece is fixed, glue is not needed between the wedge angle piece and the magnetic ring 11, the glue is prevented from polluting the light passing surface of the magneto-optical crystal 12, the insertion loss of the magneto-optical isolator is further reduced, and the packaging yield of the magneto-optical isolator is improved.

Referring to fig. 1, the magneto-optical isolator core further comprises a cylindrical shell 20 with one open end, and an end cover 21 for closing the opening of the shell 20; the magnetic ring 11, the magneto-optical crystal 12, the first wedge piece 14, the second wedge piece 15, the first support frame 16 and the second support frame 17 are all assembled in the shell 20, the first support frame 16 abuts against the bottom surface of the shell 20, and the second support frame 17 abuts against the end cover 21. The housing 20, the end cap 21, the first support frame 16 and the second support frame 17 each have a central hole coaxial with the magneto-optical crystal 12, and the aperture of the central hole is larger than the outer diameter of the magneto-optical crystal 12.

The shell 20 is a cylinder structure with one closed end and one open end, the open end is provided with threads, the end cover 21 is provided with threads matched with the open end of the shell 20, the assembled magnetic ring 11, the magneto-optical crystal 12, the first wedge angle piece 14, the second wedge angle piece 15, the first support frame 16 and the second support frame 17 are placed in the shell 20, and then the position fixing of all parts of the magneto-optical isolator core is completed by screwing the end cover 21.

Another embodiment of the present invention provides a method for manufacturing a magneto-optical isolator core as described in any one of the above, as shown in fig. 2, the method comprising:

step 201, a first welding metal layer is manufactured on the inner wall of the magnetic ring 11, and a second welding metal layer is manufactured on the outer wall of the magneto-optical crystal 12.

Wherein the first and second weld metal layers may both be gold layers; the first welding metal layer can be manufactured on the inner wall of the magnetic ring 11 through a wet electroplating process, and the second welding metal layer can be manufactured on the outer wall of the magneto-optical crystal 12 through an ion sputtering process.

Step 202, cooling the magnetic ring 11 to a first preset temperature so that the magnetic ring 11 can be sleeved on the magneto-optical crystal 12.

The first preset temperature is a preset temperature, and a person skilled in the art can set the first preset temperature according to actual conditions, which is not limited in the embodiment of the present invention. Illustratively, the first preset temperature may be-120 ℃.

Step 203, sleeving the magnetic ring 11 on the magneto-optical crystal 12, and heating the magnetic ring 11 to enable the first welding metal layer and the second welding metal layer to be connected in a pressure welding mode, so that the magneto-optical isolator core is obtained.

Further, before the first welding metal layer is formed on the inner wall of the magnetic ring 11, the method may further include: manufacturing a connecting metal layer on the inner wall of the magnetic ring 11; the connecting metal layer is used for connecting the first welding metal layer with the inner wall of the magnetic ring 11. The connection metal layer may be a copper layer, and the copper layer may be formed on the inner wall of the magnetic ring 11 by a wet plating process.

The following illustrates the fabrication and assembly process of the magneto-optical isolator core: firstly, electroplating a copper layer on the inner wall of the magnetic ring 11 by a wet method, and electroplating a gold layer on the copper layer; the outer wall of the cylindrical magneto-optical crystal 12 is plated with a gold layer by ion sputtering, so that the outer diameter of the magneto-optical crystal 12 plated with the gold layer at 25 ℃ is slightly larger than the inner diameter of the magnetic ring 11 by 1-2 microns. Then liquid nitrogen is used for cooling the magnetic ring 11, when the inner diameter of the magnetic ring 11 is matched with the outer diameter of the magneto-optical crystal 12, the magneto-optical crystal 12 is installed in an axial hole of the magnetic ring 11, and when the temperature of the magnetic ring 11 is raised back to the room temperature, the magneto-optical crystal 12 and the magnetic ring 11 are sealed. Then, the first wedge angle piece 14 is placed in a first mounting groove 18 on the end face of the magnetic ring 11, and the first support frame 16 is covered, so that the first wedge angle piece 14 is just positioned in a cavity formed by the first support frame 16 and the first mounting groove 18; the second wedge piece 15 is placed in the second mounting groove 19 at the other end of the magnetic ring 11, and the second supporting frame 17 is covered, so that the second wedge piece 15 is just positioned in a cavity formed by the second supporting frame 17 and the second mounting groove 19. And finally, putting the assembled structure into the shell 20, and screwing the end cover 21 to finish the manufacture and assembly of the magneto-optical isolator core.

The following is a specific embodiment of the magneto-optical isolator core provided by the present invention:

providing a permanent magnet ring 11 made of neodymium iron boron, wherein the outer diameter of the magnet ring 11 is 10mm, the inner diameter of the magnet ring 11 is 3mm, and the length of the magnet ring is 16mm, processing a first mounting groove 18 and a second mounting groove 19 on two end faces of the permanent magnet ring 11, and the length and the width of a sinking groove are 5mm and the depth of the sinking groove is 3 mm.

Copper layer plating on the inner wall of the magnetic ring 11: the plating solution comprises 180-220 g/L copper sulfate, 120-250 g/L sulfamic acid and 0.15-0.25 g/L sodium chloride, and the solvent is water. The process flow is (1) putting a magnetic ring into the electroplating solution to be used as a cathode; (2) processing metal copper into an anode with the diameter of 1mm, and inserting the anode into an axial hole of the magnetic ring 11; (3) the direct current power supply is introduced for electroplating, and the current density is 0.2 to 0.4A/dm²The temperature is 15-35 ℃ and the time is 60-120 s.

Plating gold layer on the inner wall of the magnetic ring 11: the plating solution contains 6-20 g/L potassium iodoaurate, 3-8 g/L, EDTA 8-15 g/L tetramethylammonium iodide, and 80-130 g/L citric acid. The process flow is (1) putting the magnetic ring 11 into the electroplating solution to be used as a cathode; (2) processing metal into an anode with the diameter of 1mm, and inserting the anode into an axial hole of a magnetic ring; (3) tong (Chinese character of 'tong')Electroplating with a DC power supply at a current density of 0.3-0.6A/dm²The temperature is 15-35 ℃ and the time is 10-60 s. The inner diameter of the magnet ring 11 was measured to be 3.004mm after the electroplating.

Processing of magneto-optical crystal 12: a TGG crystal was provided having a diameter of 3.002mm and a length of 10mm, both end faces of the crystal were polished.

Gold plating on the outer wall of the magneto-optical crystal 12: sequentially putting the magneto-optical crystal 12 into alcohol and acetone, ultrasonically cleaning for 15min respectively, removing pollutants such as surface oil stain and the like, quickly putting the magneto-optical crystal into a vacuum chamber of a film plating machine after fully drying, heating to 230 ℃, and keeping the temperature for 20-30 min; (2) adjusting the Ar gas pressure to 1.3Pa, biasing to 185V, starting a gold target power supply, modulating the current by 4A, and depositing gold by medium-frequency magnetron sputtering for 70min to finish gold plating on the surface of the upper half part of the magneto-optical crystal 12; (3) the same steps are repeated to finish the gold plating on the lower half surface of the magneto-optical crystal 12. The thickness of the gold layer is controlled at 150 nm.

Assembling the magnetic ring 11 and the magneto-optical crystal 12: the magnetic ring 11 and the magneto-optical crystal 12 are simultaneously placed in a freezing cabinet, the temperature is reduced to minus 30 ℃, the magnetic ring 11 is taken out and placed in a liquid nitrogen cooler, the flow rate of liquid nitrogen is slowly adjusted, the magnetic ring 11 is uniformly cooled to minus 120 ℃ within 10 minutes, the magneto-optical crystal 12 is taken out and placed in an axial hole of the magnetic ring 11, the liquid nitrogen is closed, and after the temperature rises, because the inner diameter of the magnetic ring 11 is slightly smaller than the outer diameter of the magneto-optical crystal 12, gold layers on the outer wall of the magneto-optical crystal 12 and the inner wall of the magnetic ring 11 are uniformly pressed and tightly.

And (3) integral packaging: using YVO₄Is prepared into a first wedge piece 14 and a second wedge piece 15 with the size of 5 multiplied by 3mm³The first wedge angle piece 14 and the second wedge angle piece 15 are respectively placed into the first installation groove 18 and the second installation groove 19, the first supporting frame 16 and the second supporting frame 17 are covered, the first supporting frame and the second supporting frame are placed into the shell 20, and the end cover 21 is screwed tightly to complete packaging.

Yet another embodiment of the present invention provides a magneto-optical isolator comprising a magneto-optical isolator core as described in any one of the above. The magneto-optical isolator core realizes the connection of the magnetic ring and the magneto-optical crystal through a low-temperature welding technology, and realizes the position fixation of the wedge angle piece through the matching of the mounting groove and the support frame. Therefore, glue is not needed in the whole assembly process of the core of the magneto-optical isolator, and the problems of large insertion loss and low packaging yield of the magneto-optical isolator caused by the fact that glue pollutes the light passing surface of the magneto-optical crystal are completely avoided.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.