阅读说明：本技术 一种集成式光隔离器的封装方法以及集成式光隔离器 (Packaging method of integrated optical isolator and integrated optical isolator ) 是由 郑熠 吴少凡 王帅华 黄鑫 徐刘伟 于 2019-10-21 设计创作，主要内容包括：本发明公开了一种集成式光隔离器的封装方法以及集成式光隔离器,涉及光纤通讯技术领域。所述方法包括：将第一磁光晶体和双折射晶体贴合形成基板；将基板划分为前段基板、中段基板和后段基板,对中段基板对应的双折射晶体表面进行离子刻蚀,在刻蚀后的第一磁光晶体上制作磁光旋转器；将前段基板对应的双折射晶体构成起偏器,将后段基板对应的双折射晶体构成检偏器；在起偏器上耦合输入光纤,在检偏器上耦合输出光纤,从而得到集成式光隔离器。本发明在第一磁光晶体贴合双折射晶体,同时制备起偏器和检偏器,产品质量高,且加工工艺简单,加工效率高,加工成本降低。(The invention discloses a packaging method of an integrated optical isolator and the integrated optical isolator, and relates to the technical field of optical fiber communication. The method comprises the following steps: attaching the first magneto-optical crystal and the birefringent crystal to form a substrate; dividing the substrate into a front section substrate, a middle section substrate and a rear section substrate, performing ion etching on the surface of the birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on the etched first magneto-optical crystal; forming a polarizer by the birefringent crystal corresponding to the front section substrate, and forming an analyzer by the birefringent crystal corresponding to the rear section substrate; and coupling the input optical fiber on the polarizer and coupling the output optical fiber on the analyzer to obtain the integrated optical isolator. According to the invention, the first magneto-optical crystal is attached to the birefringent crystal, and the polarizer and the analyzer are prepared at the same time, so that the product quality is high, the processing technology is simple, the processing efficiency is high, and the processing cost is reduced.)

1. A method of packaging an integrated optical isolator, the method comprising:

attaching the first magneto-optical crystal and the birefringent crystal to form a substrate;

dividing the substrate into a front section substrate, a middle section substrate and a rear section substrate, carrying out ion etching on the surface of the birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on the etched first magneto-optical crystal;

forming a polarizer by the birefringent crystal corresponding to the front section substrate, and forming an analyzer by the birefringent crystal corresponding to the rear section substrate;

and coupling an input optical fiber on the polarizer and coupling an output optical fiber on the analyzer to obtain the integrated optical isolator.

2. The method of packaging an integrated optical isolator of claim 1, wherein the first magneto-optical crystal and the birefringent crystal are bonded together by a pressure welding process.

3. The method of packaging an integrated optical isolator of claim 2, wherein prior to the bonding of the first magneto-optical crystal and the birefringent crystal, the method further comprises:

respectively manufacturing a connecting metal layer on one surface of the first magneto-optical crystal and one surface of the birefringent crystal; the connecting metal layer is used for connecting the first magneto-optical crystal and the birefringent crystal in a pressure welding mode.

4. The method of packaging an integrated optical isolator of claim 3, wherein prior to fabricating the connecting metal layer from the first magneto-optical crystal and the birefringent crystal, the method further comprises:

and polishing the surfaces of the first magneto-optical crystal and the birefringent crystal which are prefabricated as connecting metal layers.

5. The method of packaging an integrated optical isolator of claim 1, wherein prior to attaching the first magneto-optical crystal and the birefringent crystal to form the substrate, the method further comprises:

thinning the birefringent crystal and/or the first magneto-optical crystal.

6. The method for packaging an integrated optical isolator as claimed in claim 1, wherein the step of fabricating the magneto-optical rotator on the etched first magneto-optical crystal comprises:

and growing a second magneto-optical crystal on the etched first magneto-optical crystal, and then manufacturing a permanent magnetic film on the second magneto-optical crystal.

7. The method of packaging an integrated optical isolator of claim 6, wherein the first magneto-optical crystal and the second magneto-optical crystal are of the same type.

8. The method for packaging an integrated optical isolator as claimed in claim 1, wherein the step of configuring the polarizer with the birefringent crystal corresponding to the front substrate comprises:

after the end face of the front section substrate is polished to form a specified included angle with the lower surface of the substrate, the corresponding birefringent crystal on the front section substrate forms a polarizer;

the specific steps of forming the analyzer by the birefringent crystal corresponding to the rear substrate are as follows:

and after the end face of the rear substrate is polished to form a specified included angle with the upper surface of the substrate, the corresponding birefringent crystal on the rear substrate forms an analyzer.

9. An integrated optical isolator comprises an input optical fiber and an output optical fiber, and is characterized by further comprising an optical isolator core arranged between the input optical fiber and the output optical fiber;

the optical isolator core comprises a first magneto-optical crystal, a polarizer, an analyzer and a magneto-optical rotator;

the polarizer is fixedly arranged on the upper surface of the front section area of the first magneto-optical crystal and is connected with the input optical fiber;

the analyzer is fixedly arranged on the upper surface of the rear section area of the first magneto-optical crystal and is connected with the output optical fiber;

the magneto-optical rotator is arranged on the upper surface of the middle section area of the first magneto-optical crystal.

10. The integrated optical isolator of claim 9, wherein the magneto-optical rotator comprises a second magneto-optical crystal and a permanent magnetic film;

the second magneto-optical crystal is fixedly arranged on the first magneto-optical crystal, and the permanent magnetic film is arranged on the upper surface of the second magneto-optical crystal.

Technical Field

The invention relates to the technical field of optical fiber communication, in particular to an integrated optical isolator and a packaging method thereof.

Background

The existence of the backward light always causes self-coupling effect between optical path systems, so that the operation of a laser becomes unstable and reflection noise is generated, the gain of an optical amplifier changes and self-excitation is generated, and the whole optical fiber communication system cannot normally operate. And the optical isolator can realize forward transmission of optical signals and simultaneously restrain reverse light.

The main principle of the optical isolator is to realize irreversible transmission of light by utilizing the nonreciprocal property of magneto-optical materials for adjusting the polarization state of the light. Therefore, an optical isolator is mainly constituted by: the polarizer realizes that polarized light is obtained from natural light; a Faraday optical rotator, also called magneto-optical rotator, made of magneto-optical crystals, completes nonreciprocal adjustment of optical polarization state; the analyzer realizes the convergence and parallel emergence of the light rays.

At present, the prior art for manufacturing an integrated optical isolator generally processes a polarizer, an analyzer and a magneto-optical rotator on a crystal substrate respectively, and has the disadvantages of complex processing technology and high processing cost.

Disclosure of Invention

In view of this, the invention provides a method for packaging an integrated optical isolator, which has the advantages of simple processing technology, high processing yield and low processing cost.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

a method of packaging an integrated optical isolator, the method comprising:

attaching the first magneto-optical crystal and the birefringent crystal to form a substrate;

dividing the substrate into a front section substrate, a middle section substrate and a rear section substrate, carrying out ion etching on the surface of the birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on the etched first magneto-optical crystal;

forming a polarizer by the birefringent crystal corresponding to the front section substrate, and forming an analyzer by the birefringent crystal corresponding to the rear section substrate;

and coupling an input optical fiber on the polarizer and coupling an output optical fiber on the analyzer to obtain the integrated optical isolator.

As a still further scheme of the invention: the first magneto-optical crystal and the birefringent crystal are bonded by pressure welding.

As a still further scheme of the invention: before the first magneto-optical crystal and the birefringent crystal are bonded, the method further comprises:

respectively manufacturing a connecting metal layer on one surface of the first magneto-optical crystal and one surface of the birefringent crystal; the connecting metal layer is used for connecting the first magneto-optical crystal and the birefringent crystal in a pressure welding mode.

As a still further scheme of the invention: before the first magneto-optical crystal and the birefringent crystal are used for manufacturing the connecting metal layer, the method further comprises the following steps:

and polishing the surfaces of the first magneto-optical crystal and the birefringent crystal which are prefabricated as connecting metal layers.

As a still further scheme of the invention: before the first magneto-optical crystal and the birefringent crystal are bonded to form the substrate, the method further comprises:

thinning the birefringent crystal and/or the first magneto-optical crystal.

As a still further scheme of the invention: the specific steps of manufacturing the magneto-optical rotator on the etched first magneto-optical crystal are as follows:

and growing a second magneto-optical crystal on the etched first magneto-optical crystal, and then manufacturing a permanent magnetic film on the second magneto-optical crystal.

As a still further scheme of the invention: the first magneto-optical crystal and the second magneto-optical crystal are of the same kind.

As a still further scheme of the invention: the specific steps of forming the polarizer by the birefringent crystal corresponding to the front section substrate are as follows:

after the end face of the front section substrate is polished to form a specified included angle with the lower surface of the substrate, the corresponding birefringent crystal on the front section substrate forms a polarizer;

the specific steps of forming the analyzer by the birefringent crystal corresponding to the rear substrate are as follows:

and after the end face of the rear substrate is polished to form a specified included angle with the upper surface of the substrate, the corresponding birefringent crystal on the rear substrate forms an analyzer.

The invention also provides an integrated optical isolator processed by applying any one of the packaging methods, wherein the isolator comprises an input optical fiber and an output optical fiber, and further comprises an optical isolator core arranged between the input optical fiber and the output optical fiber;

the optical isolator core comprises a first magneto-optical crystal, a polarizer, an analyzer and a magneto-optical rotator;

the polarizer is fixedly arranged on the upper surface of the front section area of the first magneto-optical crystal and is connected with the input optical fiber;

the analyzer is fixedly arranged on the upper surface of the rear section area of the first magneto-optical crystal and is connected with the output optical fiber;

the magneto-optical rotator is arranged on the upper surface of the middle section area of the first magneto-optical crystal.

As a still further scheme of the invention: the magneto-optical rotator comprises a second magneto-optical crystal and a permanent magnetic film;

the second magneto-optical crystal is fixedly arranged on the first magneto-optical crystal, and the permanent magnetic film is arranged on the upper surface of the second magneto-optical crystal.

The beneficial effects of the invention include but are not limited to:

(1) the invention provides a packaging method of an integrated optical isolator, which comprises the following steps: attaching the first magneto-optical crystal and the birefringent crystal to form a substrate; dividing the substrate into a front section substrate, a middle section substrate and a rear section substrate, performing ion etching on the surface of the birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on the etched first magneto-optical crystal; forming a polarizer by the birefringent crystal corresponding to the front section substrate, and forming an analyzer by the birefringent crystal corresponding to the rear section substrate; and coupling the input optical fiber on the polarizer and coupling the output optical fiber on the analyzer to obtain the integrated optical isolator. Compared with the prior art, in the embodiment of the invention, after the first magneto-optical crystal is attached to the birefringent crystal forming substrate, the magneto-optical rotator is manufactured on the middle substrate after ion etching, and the front substrate and the rear substrate form the polarizer and the analyzer. The method has the advantages of simple processing technology, high processing efficiency and low processing cost.

(2) Furthermore, the first magneto-optical crystal and the birefringent crystal are connected in a pressure welding mode, the process is simple, the connection is stable, and the processing cost is further reduced; furthermore, the first magneto-optical crystal and the second magneto-optical crystal in the embodiment of the invention are the same in type, the processing difficulty is low, the cost rate is high, and the complexity of the processing technology and the processing cost are further reduced.

(3) The integrated optical isolator provided by the invention is characterized in that a first magneto-optical crystal is attached to a birefringent crystal to form a substrate, a magneto-optical rotator is manufactured on a middle substrate after ion etching, and a polarizer and an analyzer are formed by a front substrate and a rear substrate. The packaging method has the advantages of simple process, low processing cost and high processing yield.

Drawings

FIG. 1 is a flow chart of a method for packaging an integrated optical isolator according to an embodiment of the present invention;

FIG. 2 is a front view of an integrated optical isolator according to an embodiment of the present invention;

in the figure: 1-a first magneto-optical crystal; 2-a polarizer; 3-an analyzer; 4-a second magneto-optical crystal; 5-permanent magnetic film; 6-input optical fiber; 7-output optical fiber.

Detailed Description

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

An embodiment of the present invention provides a method for packaging an integrated optical isolator, as shown in fig. 1, the method includes:

step 101, attaching the first magneto-optical crystal 1 and the birefringent crystal to form a substrate.

The first magneto-optical crystal 1 and the birefringent crystal may be configured in a rectangular parallelepiped shape or a square shape with the same size, and the birefringent crystal is covered on the first magneto-optical crystal 1.

The first magneto-optical crystal 1 may be any one of the existing magneto-optical crystals, such as: an yttrium iron garnet system YIG, a doped YIG system; gallate garnet system GGG, TGG; the rare earth aluminate garnet system TAG, TAG-TGG, etc., which is not limited by the embodiment of the invention.

The birefringent crystal may be any birefringent crystal known in the art, such as: calcite, lithium niobate, lithium tantalate, yttrium vanadate, and the like, which are not limited in the embodiment of the present invention.

102, dividing the substrate into a front section substrate, a middle section substrate and a rear section substrate, performing ion etching on the surface of the birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on the etched first magneto-optical crystal 1.

The substrate is divided into a front substrate, a middle substrate and a rear substrate, and a person skilled in the art can set the substrates according to actual conditions, which is not limited in the embodiments of the present invention.

And performing ion etching on the surface of the birefringent crystal corresponding to the middle substrate, and after the birefringent crystal on the middle substrate is completely removed, manufacturing a magneto-optical rotator on the exposed first magneto-optical crystal 1, wherein the magneto-optical rotator can be used for completing non-reciprocal adjustment of the polarization state of light and rotating the linearly polarized light by 45 degrees.

And 103, forming the polarizer 2 by the birefringent crystal corresponding to the front-stage substrate, and forming the analyzer 3 by the birefringent crystal corresponding to the rear-stage substrate.

And 104, coupling an input optical fiber 6 on the polarizer 2 and coupling an output optical fiber 7 on the analyzer 3 to obtain the integrated optical isolator.

The invention provides a packaging method of an integrated optical isolator, which is characterized in that a substrate is formed by attaching a first magneto-optical crystal 1 and a birefringent crystal; dividing a substrate into a front section substrate, a middle section substrate and a rear section substrate, performing ion etching on the surface of a birefringent crystal corresponding to the middle section substrate, and manufacturing a magneto-optical rotator on an etched first magneto-optical crystal 1; the birefringent crystal corresponding to the front section substrate forms a polarizer 2, and the birefringent crystal corresponding to the rear section substrate forms an analyzer 3; an input optical fiber 6 is coupled on the polarizer 2, and an output optical fiber 7 is coupled on the analyzer 3, so that the integrated optical isolator is obtained. According to the invention, the first magneto-optical crystal 1 is attached to the birefringent crystal, the polarizer 2 and the analyzer 3 are simultaneously prepared, the product quality is high, the processing technology is simple, the processing efficiency is high, and the processing cost is reduced.

Furthermore, the first magneto-optical crystal 1 and the birefringent crystal are bonded by pressure welding.

Wherein the birefringent crystal and the first magneto-optical crystal 1 are connected by applying pressure to the birefringent crystal.

Further, before the first magneto-optical crystal 1 and the birefringent crystal are bonded, the method may further include: respectively manufacturing a connecting metal layer on one surface of the first magneto-optical crystal 1 and one surface of the birefringent crystal; the connecting metal layer is used for connecting the first magneto-optical crystal 1 and the birefringent crystal in a pressure welding mode. The connection metal layer may be a tin film, and the tin film may be formed on the surfaces of the first magneto-optical crystal 1 and the birefringent crystal by an evaporation tin plating process.

Further, before the first magneto-optical crystal 1 and the birefringent crystal are made into the connection metal layer, the method may further include: the first magneto-optical crystal 1 and the birefringent crystal are pre-fabricated as surface finishes of the connecting metal layer. Wherein, the polishing method can be hydraulic polishing, magneto-rheological polishing, fluid polishing and the like.

Further, before the first magneto-optical crystal 1 and the birefringent crystal are bonded to form the substrate, the method may further include: the birefringent crystal and/or the first magneto-optical crystal 1 is thinned. The thinning method can be chemical mechanical grinding, magnetic fluid thinning and the like. The volume of the product can be further reduced by thinning.

Further, the specific steps of manufacturing the magneto-optical rotator on the etched first magneto-optical crystal 1 are as follows:

a second magneto-optical crystal 4 is grown on the etched first magneto-optical crystal 1, and then a permanent magnetic film 5 is formed on the second magneto-optical crystal 4.

Wherein the second magneto-optical crystal 4 may be grown on the first magneto-optical crystal 1 by proton exchange.

The permanent magnetic film 5 can be manufactured on the second magneto-optical crystal 4 by electrodeposition, magnetron sputtering, laser pulse deposition, and the like.

Further, the first magneto-optical crystal 1 and the second magneto-optical crystal 4 are of the same kind. By adopting the arrangement, the proton exchange growth difficulty of the same crystal is small, the yield is high, and the processing cost is low.

Further, the specific steps of forming the polarizer 2 from the birefringent crystal corresponding to the front substrate are as follows: after the end face of the front section substrate is polished to form a specified included angle with the lower surface of the substrate, the polarizer 2 is formed by the corresponding birefringent crystal on the front section substrate;

the specific steps of forming the analyzer 3 by the birefringent crystal corresponding to the rear substrate are as follows: after the end face of the rear substrate is polished to form a specified included angle with the upper surface of the substrate, the corresponding birefringent crystal on the rear substrate forms an analyzer 3.

Wherein the above-mentioned designated included angles are all 22.5 °, with this arrangement, the laser light input by the input optical fiber 6 can be output through the analyzer 3, while the reverse light is rotated and cannot pass through the polarizer 2.

The following illustrates the packaging method of the integrated optical isolator: firstly, plating tin on one surface of the first magneto-optical crystal 1, and plating tin on one surface of the birefringent crystal; the first magneto-optical crystal 1 is connected with the tin-plated surface of the birefringent crystal through a pressure welding process, and the first magneto-optical crystal 1 and the birefringent crystal are thinned to form a substrate. Then dividing the substrate into three parts for manufacturing a polarizer 2, a magneto-optical rotator and an analyzer 3 according to the design size, removing the birefringent crystal of the part for manufacturing the magneto-optical rotator by adopting ion etching and exposing the first magneto-optical crystal 1, growing a second magneto-optical crystal 4 on the exposed surface of the first magneto-optical crystal 1 by a proton exchange method, and manufacturing a permanent magnetic film 5 on the second magneto-optical crystal 4 to form the magneto-optical rotator. And then, polishing the end face of the part for manufacturing the polarizer 2 to form a specified included angle with the lower surface of the substrate to form the polarizer 2, and polishing the end face of the part for manufacturing the analyzer 3 to form a specified included angle with the upper surface of the substrate to form the analyzer 3. And finally, coupling the input optical fiber 6 and the output optical fiber 7 with the polarizer 2 and the analyzer 3 respectively, and packaging into an integrated optical isolator.

The following is a specific embodiment of the integrated optical isolator packaging method provided by the invention:

providing a first magneto-optical crystal 1 made of yttrium iron garnet (YIG crystal for short), and performing evaporation tin plating on one surface of the YIG crystal, wherein the coating parameters are evaporation boat current 550A, voltage 5-7V and vacuum degree (5-7) multiplied by 10^-3Pa, the thickness of the tin film is 1 μm.

Providing a birefringent crystal made of yttrium vanadate crystal (YVO)⁴Crystalline) in YVO⁴One surface of the crystal is plated with tin by evaporation, the parameters of the plating are that the current of an evaporation boat is 550A, the voltage is 5-7V, and the vacuum degree is (5-7) multiplied by 10^-3Pa, the thickness of the tin film is 1 μm.

YIG crystal and YVO are pressed and welded by vacuum⁴The tin-plated surface of the crystal is tightly welded, and the parameters of the vacuum pressure welding process are as follows: degree of vacuum (2-3) × 10^-4Pa, pressure 25Kg/cm²And the ambient temperature is 120 ℃. Then the YIG crystal and YVO are mixed⁴And thinning the crystal to form a substrate.

Then the substrate is divided into three parts for manufacturing a polarizer 2, a magneto-optical rotator and an analyzer 3 according to the design size. YVO to be used for preparing magneto-optical rotator part⁴Removing the crystal by ion etching to expose the YIG crystal surface, wherein the etching depth is about 2 μm; another YIG crystal is grown on the exposed YIG crystal face by proton exchange method, and deposited on the newly grown YIG crystal 4A permanent magnetic film 5 is deposited to constitute a magneto-optical rotator.

And then, polishing the end face of the part for manufacturing the polarizer 2 to form an included angle of 22.5 degrees with the lower surface of the substrate to form the polarizer 2, and polishing the end face of the part for manufacturing the analyzer 3 to form an included angle of 22.5 degrees with the upper surface of the substrate to form the analyzer 3.

And finally, coupling the input optical fiber 6 and the output optical fiber 7 with the polarizer 2 and the analyzer 3 respectively, and packaging into an integrated optical isolator.

Another embodiment of the present invention provides an integrated optical isolator manufactured by applying the packaging method of the integrated optical isolator described in any one of the above embodiments, as shown in fig. 2, including an input optical fiber 6 and an output optical fiber 7, and further including an optical isolator core disposed between the input optical fiber 6 and the output optical fiber 7;

the optical isolator core comprises a first magneto-optical crystal 1, a polarizer 2, an analyzer 3 and a magneto-optical rotator;

the polarizer 2 is fixedly arranged on the upper surface of the front section area of the first magneto-optical crystal 1, and the polarizer 2 is connected with the input optical fiber 6;

the analyzer 3 is fixedly arranged on the upper surface of the rear section area of the first magneto-optical crystal 1, and the analyzer 3 is connected with the output optical fiber 7;

the magneto-optical rotator is disposed on the upper surface of the middle section region of the first magneto-optical crystal 1.

The first magneto-optical crystal 1 may be any one of the existing magneto-optical crystals, such as: an yttrium iron garnet system YIG, a doped YIG system; gallate garnet system GGG, TGG; the rare earth aluminate garnet system TAG, TAG-TGG, etc., which is not limited by the embodiment of the invention.

The polarizer 2 and the analyzer 3 are birefringent crystals, and may be any birefringent crystal known in the art, such as: calcite, lithium niobate, lithium tantalate, yttrium vanadate, and the like, which are not limited in the embodiment of the present invention.

Referring to fig. 2, the end surfaces of the polarizer 2 and the front section of the first magneto-optical crystal 1 and the lower surface of the first magneto-optical crystal 1 are set to a specified angle, and the end surfaces of the analyzer 3 and the rear section of the first magneto-optical crystal 1 and the upper surface of the analyzer 3 are set to a specified angle, which is 22.5 °.

Further, the magneto-optical rotator comprises a second magneto-optical crystal 4 and a permanent magnetic film 5;

the second magneto-optical crystal 4 is fixedly arranged on the first magneto-optical crystal 1, and the permanent magnetic film 5 is arranged on the upper surface of the second magneto-optical crystal 4.

The second magneto-optical crystal 4 may be any one of the existing magneto-optical crystals, such as: an yttrium iron garnet system YIG, a doped YIG system; gallate garnet system GGG, TGG; the rare earth aluminate garnet system TAG, TAG-TGG, etc., which is not limited by the embodiment of the invention.

The permanent magnetic film 5 can be any one of an aluminum-nickel-cobalt permanent magnetic alloy, an iron-chromium-cobalt permanent magnetic alloy, a permanent magnetic ferrite, a rare earth permanent magnetic material, a composite permanent magnetic material and the like. The permanent magnetic film 5 can be manufactured on the second magneto-optical crystal 4 by electrodeposition, magnetron sputtering, laser pulse deposition, and the like.

The integrated optical isolator provided by the invention is characterized in that a polarizer 2 and an analyzer 3 are respectively arranged on the front section area and the rear section area of a first magneto-optical crystal 1, and a magneto-optical rotator is arranged in the middle section area of the first magneto-optical crystal 1; the magneto-optical rotator comprises a second magneto-optical crystal 4 arranged on a first magneto-optical crystal 1, a permanent magnetic film 5 arranged on the second magneto-optical crystal 4, an input optical fiber 6 connected with a polarizer 2 and an output optical fiber 7 connected with an analyzer 3, and isolation of reverse light is achieved.

In the embodiment, laser light input by an input optical fiber 6 is divided into linearly polarized o light and e light through a polarizer 2, the polarization direction of the linearly polarized light rotates anticlockwise by 45 degrees after passing through a magnetic light rotator, the o light and the e light are refracted together after passing through an analyzer 3 with an optical axis angle of 45 degrees, and the coupled light is output from an output optical fiber 7. The reverse light is divided into linearly polarized o 'light and e' light after passing through the analyzer 3, the polarization direction of the light is rotated by 45 degrees counterclockwise, and the polarization direction of the light is further rotated by 45 degrees counterclockwise after passing through the second magneto-optical crystal 4 coated with the permanent magnetic film 5. The o 'light and the e' light have been deflected by 90 ° respectively with respect to the polarization directions of the o light and the e light upon reaching the polarizer 2, and thus cannot be refracted together by the polarizer 2.

Thereby acting as an optical isolator.

Wherein the thickness of the coated permanent magnetic film 5 is determined by the length of the second magneto-optical crystal 4 and its Verdet constant. The angle θ by which the polarization direction of the outgoing linearly polarized light is rotated with respect to the incoming linearly polarized light can be expressed as: θ ═ VHL.

Wherein V represents a Verdet constant;

h represents the magnetic field strength of the external magnetic field acting in the direction of the principal axis of the second magneto-optical crystal 4;

l represents the distance light travels within the second magneto-optical crystal 4.

Therefore, when the rotation angle of the polarization direction of the emergent ray polarized light, the characteristics of the second magneto-optical crystal 4 and the laser wavelength are determined, namely theta, H and L are determined, V is determined; when the composition of the permanent magnet thin film 5 is selected, the thickness of the permanent magnet thin film 5 is also uniquely determined.

The above description is only for the purpose of illustrating the present invention and is not intended to limit the present invention in any way, and the present invention is not limited to the above description, but rather should be construed as being limited to the scope of the present invention.