Faraday rotator, optical isolator and optical circulator

Abstract

The utility model is suitable for the technical field of optical equipment, and provides a Faraday rotator, an optical isolator and an optical circulator. The Faraday rotator comprises a magneto-optical component and a magnetic field applying piece, and the magnetic field applying piece can apply an external magnetic field to the magneto-optical component; the magneto-optical component can enable the polarization state of the polarized light to rotate by a preset angle along a first turning direction in an external magnetic field, and the preset angle forms an optical rotation angle; the magneto-optical component is provided with a light incident surface and a reflecting surface which are oppositely arranged, a first light-transmitting film and a second light-transmitting film are sequentially arranged on the light incident surface, and a first reflecting film is arranged on the reflecting surface; when one of the first light-transmitting film and the second light-transmitting film passes through the polarized light propagating toward the first reflective film, the other passes through the polarized light and emits the polarized light to the outside of the magneto-optical member. By means of the design, the Faraday rotator can still achieve the original effect on the premise that the size of the magnetic field generating piece is reduced, and reduction of the overall size of the Faraday rotator is facilitated.

Description

Technical Field

[0001] The present application belongs to the technical field of optical equipment, and more specifically, relates to a Faraday rotator, an optical isolator, and an optical circulator. Background Art

[0002] Optical isolators and optical circulators are specialized optical devices used to control the direction of light propagation. Their nonreciprocal properties allow light to pass in one direction while blocking the reverse direction. Optical isolators effectively reduce the negative effects of reflected light on laser and optical system performance, while optical circulators also enable bidirectional communication and crosstalk prevention.

[0003] In optical isolators and optical circulators, a Faraday rotator achieves unidirectional light transmission by rotating the polarization state of polarized light. The angle of optical rotation is positively correlated with the magnetic field strength within the Faraday rotator, which in turn is related to the size of the magnetic field generator within the Faraday rotator. A larger size generally produces a stronger magnetic field effect, thereby increasing the angle of optical rotation. However, this design can increase the size of the Faraday rotator, which in turn increases the overall size and cost of the optical isolator and optical circulator. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide a Faraday rotator, an optical isolator, and an optical circulator, aiming to solve the technical problem of the large size of the Faraday rotator in the related art.

[0005] To achieve the above-mentioned purpose, according to one aspect of the present application, a Faraday rotator is provided, comprising a magneto-optical component and a magnetic field applicator, the magnetic field applicator being capable of applying an external magnetic field to the magneto-optical component; the magneto-optical component being capable of rotating the polarization state of polarized light along a first direction by a preset angle in the external magnetic field, the preset angle being formed as an optical rotation angle; the magneto-optical component having a light incident surface and a reflective surface arranged opposite to each other, the light incident surface being provided with a first light-transmitting film and a second light-transmitting film in sequence, and the reflective surface being provided with a first reflective film; the first light-transmitting film and the second light-transmitting film being capable of allowing polarized light propagating toward the first reflective film to pass through, the first reflective film being capable of reflecting polarized light toward the first light-transmitting film or the second light-transmitting film, and the first light-transmitting film and the second light-transmitting film being capable of allowing polarized light to pass through and be emitted out of the magneto-optical component; when one of the first light-transmitting film and the second light-transmitting film allows polarized light propagating toward the first reflective film to pass through, the other allows polarized light to pass through and be emitted out of the magneto-optical component.

[0006] Optionally, a second reflective film is provided on the light incident surface, which is located between the first light-transmitting film and the second light-transmitting film and can reflect the polarized light toward the first reflective film; the first reflective film can reflect the polarized light toward the second reflective film and can finally reflect the polarized light toward the first light-transmitting film or the second light-transmitting film.

[0007] According to another aspect of the present application, an optical isolator is provided, comprising an optical rotator and the aforementioned Faraday rotator; the optical rotator is located on a side of the light incident surface away from the reflective surface and is covered with a first light-transmitting film; the optical rotator is capable of allowing polarized light incident from a side of the optical rotator away from the magneto-optical component to pass therethrough, and is capable of rotating the polarization state of the polarized light by a preset angle along a second direction, the second direction being opposite to the first direction.

[0008] Optionally, the optical isolator further comprises an incident element, a polarizing element and a receiving element, wherein the incident element, the polarizing element, the optical rotator and the magneto-optical component are spaced apart along a first preset direction; the incident element is capable of emitting polarized light toward the polarizing element; the polarizing element is capable of converting the polarized light into a first preset polarized light and a second preset polarized light, and is capable of allowing the first preset polarized light to pass through, and is capable of reflecting the second preset polarized light, and the polarization state of the second preset polarized light differs from the polarization state of the first preset polarized light by 90°; the receiving element is located on a side of the polarizing element away from the magneto-optical component, and is spaced apart from the incident element along a second preset direction, and an angle is formed between the second preset direction and the first preset direction; the receiving element is capable of receiving polarized light that passes through the first light-transmitting film, the second light-transmitting film and the polarizing element in sequence; the optical rotator is capable of allowing the polarized light incident from the side of the optical rotator close to the magneto-optical component to pass through, and is capable of rotating the polarization state of the polarized light by a preset angle along the first direction.

[0009] Optionally, the polarizer includes a first polarizing prism and a second polarizing prism, the first polarizing prism covers the first light-transmitting film; the second polarizing prism is located on one side of the first polarizing prism and covers the second light-transmitting film.

[0010] Optionally, the optical isolator further includes a filter element, which is located between the incident element and the polarizing element, and between the receiving element and the polarizing element; the filter element covers the incident element and the receiving element, and is capable of allowing polarized light to pass through.

[0011] Optionally, the filter includes a first zero-degree polarizer, which is located between the incident element and the polarizer, covers the incident element, and allows polarized light to pass through; the filter also includes a second zero-degree polarizer, which is located between the receiving element and the polarizer, covers the receiving element, and allows polarized light to pass through.

[0012] Optionally, the optical isolator further comprises a light-blocking plate, wherein the first zero-degree polarizer, the first polarizing prism and the optical rotator are located on a first side of the light-blocking plate, the second zero-degree polarizer and the second polarizing prism are located on a second side of the light-blocking plate, and the first side and the second side are arranged opposite to each other; and / or, the first zero-degree polarizer and the second zero-degree polarizer have the same structure; and / or, the first polarizing prism and the second polarizing prism have the same structure.

[0013] According to another aspect of the present application, an optical circulator is provided, comprising a first optical rotator and the aforementioned Faraday rotator. The first optical rotator is located on a side of a light incident surface away from a reflective surface and is covered with a first light-transmitting film. The first optical rotator is capable of allowing polarized light incident from a side of the first optical rotator away from the magneto-optical component to pass therethrough and of rotating the polarization state of the polarized light by a preset angle along a second direction, the second direction being opposite to the first direction.

[0014] Optionally, the optical circulator further comprises a first collimator, a second collimator, a third collimator, a polarization component and a second optical rotation component, wherein the first collimator, the polarization component, the first optical rotation component and the magneto-optical component are spaced apart along a first preset direction; the first collimator can emit polarized light toward the polarization component; the polarization component can convert the polarized light into a first preset polarized light and a second preset polarized light, and can allow the first preset polarized light to pass through and can reflect the second preset polarized light, and the polarization state of the second preset polarized light differs from the polarization state of the first preset polarized light by 90°; the second collimator is located on a side of the polarization component away from the magneto-optical component, and is spaced apart from the first collimator along a second preset direction, and the second preset direction has an angle with the first preset direction; the second collimator can receive light that passes through the first light-transmitting film, the second light-transmitting film and the polarization component in sequence polarized light; the first optical rotator component is capable of transmitting polarized light incident on the side of the first optical rotator component close to the magneto-optical component, and is capable of rotating the polarization state of the polarized light by a preset angle along a first direction; the third collimator, the second optical rotator component, and the polarization component are spaced apart along a second preset direction; the third collimator is capable of receiving polarized light that has sequentially passed through the second light-transmitting film, the first light-transmitting film, the first optical rotator component, the polarization component, and the second optical rotator component; the second optical rotator component is capable of transmitting polarized light incident on the side of the second optical rotator component close to the polarization component, and is capable of rotating the polarization state of the polarized light by an angle twice the preset angle along a second direction, the second direction being opposite to the first direction; the second optical rotator component is also capable of transmitting polarized light incident on the side of the second optical rotator component close to the third collimator, and is capable of rotating the polarization state of the polarized light by an angle twice the preset angle along the first direction.

[0015] The Faraday rotator provided by the present application has the following beneficial effects: when rotating the polarization state of polarized light, the Faraday rotator first causes polarized light propagating toward the first reflective film to pass through one of the first and second transparent films. The polarized light is then reflected by the first reflective film toward the other of the first and second transparent films, passing through the other film and exiting the magneto-optical component, thereby extending the propagation path of the polarized light within the magneto-optical component. The angle of optical rotation is positively correlated not only with the magnetic field intensity but also with the propagation length of the polarized light within the magneto-optical component. The magneto-optical component provided with the first, second, and first transparent films in the present application can reflect polarized light within the magneto-optical component, thereby extending the propagation path of the polarized light within the component. This design enables the Faraday rotator to achieve its original effect while reducing the size of the magnetic field generating element, thus contributing to a reduction in the overall size of the Faraday rotator and thus facilitating miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 A schematic structural diagram of a magneto-optical component capable of reflecting polarized light once, provided in an embodiment of the present application;

[0018] Figure 2 A schematic structural diagram of a magneto-optical component capable of reflecting polarized light three times, provided in an embodiment of the present application;

[0019] Figure 3 A schematic structural diagram of a magneto-optical component capable of reflecting polarized light five times, provided in an embodiment of the present application;

[0020] Figure 4 A schematic diagram illustrating a forward light path of an optical isolator without a filter and a light baffle provided in an embodiment of the present application;

[0021] Figure 5 A schematic diagram illustrating a reverse light path of an optical isolator without a filter and a light baffle provided in an embodiment of the present application;

[0022] Figure 6 A schematic diagram illustrating the polarization state of polarized light in a forward optical path of an optical isolator without a filter and a light baffle provided in an embodiment of the present application;

[0023] Figure 7A schematic diagram illustrating the polarization state of polarized light in a reverse optical path of an optical isolator without a filter and a light baffle provided in an embodiment of the present application;

[0024] Figure 8 A schematic diagram illustrating a forward light path of an optical isolator without a light baffle provided in an embodiment of the present application;

[0025] Figure 9 A schematic diagram illustrating a reverse light path of an optical isolator without a light baffle provided in an embodiment of the present application;

[0026] Figure 10 A schematic diagram illustrating a forward light path of an optical isolator provided in an embodiment of the present application;

[0027] Figure 11 A schematic diagram illustrating a reverse optical path of an optical isolator provided in an embodiment of the present application;

[0028] Figure 12 A schematic diagram of the optical circulator provided in an embodiment of the present application illustrating a forward light path where light is incident on the first collimator and received by the second collimator;

[0029] Figure 13 A schematic diagram of the optical circulator provided in an embodiment of the present application showing a forward light path where light is incident on the second collimator and received by the third collimator;

[0030] Figure 14 A schematic diagram illustrating a reverse optical path of an optical circulator provided in an embodiment of the present application;

[0031] Figure 15 A schematic diagram of the polarization state of the optical circulator provided in an embodiment of the present application, in which the polarized light in the forward optical path is incident on the first collimator and received by the second collimator;

[0032] Figure 16 A schematic diagram of the polarization state of the optical circulator provided in an embodiment of the present application, in which the second collimator is incident and the third collimator receives the polarized light in the forward optical path;

[0033] Figure 17 A schematic diagram illustrating the polarization state of polarized light in a reverse optical path of an optical circulator provided in an embodiment of the present application;

[0034] The reference numerals used in the above drawings are as follows:

[0035] 100, magneto-optical component; 110, light incident surface; 111, first light-transmitting film; 112, second light-transmitting film; 113, second reflective film; 120, reflective surface; 121, first reflective film;

[0036] 200, optical rotation parts;

[0037] 300, incident piece;

[0038] 400, polarizing element; 410, first polarizing prism; 420, second polarizing prism;

[0039] 500, receiving items;

[0040] 600, filter; 610, first zero-degree polarizer; 620, second zero-degree polarizer;

[0041] 700, light barrier;

[0042] 800, first optical rotation component; 900, first collimator; 1000, second collimator; 1100, third collimator; 1200, polarization component; 1300, second optical rotation component. DETAILED DESCRIPTION

[0043] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0044] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element. The embodiments and features in the embodiments of this application may be combined with each other unless there is a conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0045] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means more than two, unless otherwise specifically defined.

[0047] As described in the background technology, optical isolators and optical circulators are two special optical devices that are mainly used to control the propagation direction of light. They have non-reciprocal properties, allowing light to pass in one direction while preventing the transmission of reverse light. Optical isolators can effectively reduce the adverse effects of reflected light on the performance of lasers and optical systems. Optical circulators also have capabilities such as bidirectional communication and crosstalk prevention. In optical isolators and optical circulators, Faraday rotators achieve unidirectional transmission of light by rotating the polarization state of polarized light. The optical rotation angle is positively correlated with the magnetic field strength in the Faraday rotator, which in turn is related to the size of the magnetic field generating element in the Faraday rotator. A larger size usually produces a stronger magnetic field effect, thereby increasing the optical rotation angle. However, this design may lead to an increase in the volume of the Faraday rotator, which in turn leads to an increase in the overall size of the optical isolator and optical circulator, increasing the cost.

[0048] Reference Figure 1 In order to solve the above problems, according to one aspect of the present application, an embodiment of the present application provides a Faraday rotator, which includes a magneto-optical component 100 and a magnetic field applicator, and the magnetic field applicator can apply an external magnetic field to the magneto-optical component 100; the magneto-optical component 100 can rotate the polarization state of polarized light along a first direction by a preset angle in the external magnetic field, and the preset angle is formed as an optical rotation angle.

[0049] The magneto-optical component 100 has a light incident surface 110 and a reflective surface 120 that are relatively arranged. A first light-transmitting film 111 and a second light-transmitting film 112 are sequentially provided on the light incident surface 110, and a first reflective film 121 is provided on the reflective surface 120. Both the first light-transmitting film 111 and the second light-transmitting film 112 can allow polarized light propagating toward the first reflective film 121 to pass through. The first reflective film 121 can reflect polarized light toward the first light-transmitting film 111 or the second light-transmitting film 112. Both the first light-transmitting film 111 and the second light-transmitting film 112 can allow polarized light to pass through and be emitted to the outside of the magneto-optical component 100.

[0050] While one of the first light-transmitting film 111 and the second light-transmitting film 112 allows the polarized light traveling toward the first reflective film 121 to pass therethrough, the other allows the polarized light to pass therethrough and emit it to the outside of the magneto-optical component 100 .

[0051] In the embodiment of the present application, the magneto-optical component 100 is a magneto-optical crystal, which can be made of materials such as neodymium iron boron (NdFeB), lanthanum ferrite (La1-xSrxMnO3), lanthanum strontium barium titanate (LSMO) or quartz; the magneto-optical crystal is in the shape of a parallelepiped or a round rod. In addition, the light incident surface 110 and the reflection surface 120 are both single planes. In other embodiments, the light incident surface 110 can also be a curved surface, a folded surface, an interface or an adjacent surface, and the reflection surface 120 can also be a curved surface, a folded surface, an interface or an adjacent surface. The magnetic field applicator is a permanent magnet or an electromagnet. The first light-transmitting film 111 is an anti-reflection film, the second light-transmitting film 112 is an anti-reflection film, and the first reflection film 121 is a high-reflection film; at the same time, the first light-transmitting film 111, the second light-transmitting film 112 and the first reflection film 121 can be installed on the corresponding surfaces by a bonding process, a hot pressing process, a deposition process, a spraying process or a coating process.

[0052] In a specific embodiment, when the Faraday rotator adjusts the polarization state of polarized light, the polarized light passes through the first light-transmitting film 111 and propagates toward the first reflective film 121. The polarized light reflected by the first reflective film 121 propagates toward the second light-transmitting film 112 and passes through the second light-transmitting film 112 to be emitted outside the magneto-optical component 100. In this case, the polarized light undergoes one reflection inside the magneto-optical component 100.

[0053] In another specific embodiment, when the Faraday rotator adjusts the polarization state of the polarized light, the polarized light passes through the second light-transmitting film 112 and propagates toward the first reflective film 121. The polarized light reflected by the first reflective film 121 propagates toward the first light-transmitting film 111 and passes through the first light-transmitting film 111 to be emitted outside the magneto-optical component 100. In this case, the polarized light undergoes one reflection inside the magneto-optical component 100.

[0054] When the Faraday rotator of the present application rotates the polarization state of polarized light, it first causes the polarized light propagating toward the first reflective film 121 to pass through one of the first light-transmitting film 111 and the second light-transmitting film 112. The polarized light is reflected toward the other of the first light-transmitting film 111 and the second light-transmitting film 112 under the reflection action of the first reflective film 121, and passes through the other to be emitted to the outside of the magneto-optical component 100, so as to extend the propagation path of the polarized light in the magneto-optical component 100. The optical rotation angle is not only positively correlated with the magnetic field intensity, but also positively correlated with the propagation length of the polarized light in the magneto-optical component 100. The magneto-optical component 100 provided with the first light-transmitting film 111, the second light-transmitting film 112 and the first reflective film 121 in the present application can reflect the polarized light in the magneto-optical component 100, thereby extending the propagation path of the polarized light in the magneto-optical component 100. This design enables the Faraday rotator to achieve the original effect while reducing the size of the magnetic field generating component, which helps to reduce the overall size of the Faraday rotator and thus helps to miniaturize the Faraday rotator.

[0055] Reference Figure 2 and Figure 3 In one embodiment, a second reflective film 113 is further provided on the light incident surface 110. The second reflective film 113 is located between the first light-transmitting film 111 and the second light-transmitting film 112, and can reflect polarized light toward the first reflective film 121; the first reflective film 121 can reflect polarized light toward the second reflective film 113, and can finally reflect the polarized light toward the first light-transmitting film 111 or the second light-transmitting film 112.

[0056] In this embodiment, the second reflective film 113 is a highly reflective film and can be mounted on the light incident surface 110 using a bonding process, a hot pressing process, a deposition process, a spraying process, or a coating process. Furthermore, the magneto-optical crystal has an angle β; the number of reflections of polarized light within the magneto-optical component 100 can be adjusted by changing the incident angle of the polarized light, the size of the first light-transmitting film 111, the size of the second light-transmitting film 112, the size of the first reflective film 121, the size of the second reflective film 113, the size of β, and the size of the polarized light spot.

[0057] In a specific embodiment, when the Faraday rotator adjusts the polarization state of polarized light, the polarized light passes through the first transparent film 111 and propagates toward the first reflective film 121. The polarized light reflected by the first reflective film 121 propagates toward the second reflective film 113, and the polarized light reflected by the second reflective film 113 propagates toward the first reflective film 121. With the cooperation of the first reflective film 121 and the second reflective film 113, the polarized light is reflected 2n+1 times (n is 1, 2, 3...), and finally reflected by the first reflective film 121 and propagates toward the second transparent film 112, and passes through the second transparent film 112 to be emitted outside the magneto-optical component 100.

[0058] In another specific embodiment, when the Faraday rotator adjusts the polarization state of polarized light, the polarized light passes through the second light-transmitting film 112 and is reflected toward the first reflective film 121. The polarized light reflected by the first reflective film 121 propagates toward the second reflective film 113, and the polarized light reflected by the second reflective film 113 propagates toward the first reflective film 121. With the cooperation of the first reflective film 121 and the second reflective film 113, the polarized light is reflected 2n+1 times (n is 1, 2, 3...), and finally propagates toward the first light-transmitting film 111 after being reflected by the second reflective film 113, and is emitted from the magneto-optical component 100.

[0059] The first reflective film 121 and the second reflective film 113 used in the present application further extend the propagation path of the polarized light in the magneto-optical component 100, which helps to further reduce the size of the magnetic field generating element while achieving the original effect, thereby reducing the overall size of the Faraday rotator.

[0060] Reference Figures 1 to 3 According to another aspect of the present application, an embodiment of the present application further provides an optical isolator, which includes the above-mentioned Faraday rotator.

[0061] When rotating the polarization state of polarized light, the optical isolator of the present application first causes polarized light traveling toward the first reflective film 121 to pass through one of the first light-transmitting film 111 and the second light-transmitting film 112. Reflected by the first reflective film 121, the polarized light is then reflected toward the other of the first and second light-transmitting films 111 and 112, passing through the other film and exiting the magneto-optical component 100, thereby extending the propagation path of the polarized light within the magneto-optical component 100. The angle of optical rotation is positively correlated not only with the magnetic field intensity but also with the propagation length of the polarized light within the magneto-optical component 100. The magneto-optical component 100 of the present application, equipped with the first and second light-transmitting films 111, 112, and first reflective film 121, can reflect polarized light within the magneto-optical component 100, thereby extending the propagation path of the polarized light within the magneto-optical component 100. This design enables the Faraday rotator to achieve its original effect while reducing the size of the magnetic field generating element, thus contributing to a reduction in the overall size of the Faraday rotator and thus facilitating miniaturization. In addition, the magneto-optical component 100 in the present application can also allow polarized light to enter from the light incident surface 110 and emit from the light incident surface 110, which not only helps to miniaturize and simplify the optical isolator, but also can effectively block reverse light, thereby improving the stability of the optical isolator and the quality and intensity of the optical signal.

[0062] Reference Figures 4 to 7 In one embodiment, the optical isolator further includes a light rotator 200, which is located on a side of the light incident surface 110 away from the reflective surface 120 and covers the first light-transmitting film 111. The light rotator 200 can allow polarized light incident from a side of the light rotator 200 away from the magneto-optical component 100 to pass through, and can rotate the polarization state of the polarized light by a preset angle along a second direction, where the second direction is opposite to the first direction.

[0063] In this embodiment, the optically active element 200 is an optically active crystal, which is a 22.5° half-wave plate or a component made of any one of quartz, sodium calcium aluminum silicate (NaCaAlSiO4), and magnesium aluminum spinel (MgAl2O4). In addition, the optically active crystal is only placed in the upper half of the central axis of the crystal.

[0064] In one specific embodiment, polarized light with a polarization state of 0° (i.e., a straight line) is incident on the optical rotator 200 from the side of the optical rotator 200 away from the magneto-optical component 100 and passes through the optical rotator 200. During this process, the polarization state of the polarized light rotates 45° counterclockwise. The polarized light then passes through the first light-transmitting film 111 and propagates toward the first reflective film 121. Finally, the polarized light is emitted from the magneto-optical component 100 through the second light-transmitting film 112. During this process, the polarization state of the polarized light rotates 45° clockwise, at which point the polarization state of the polarized light returns to 0°.

[0065] The optical rotator 200 and the Faraday rotator used in conjunction with each other in the present application can not only restore the polarization state of polarized light to ensure the integrity of the optical signal, but also reduce the attenuation and distortion of the optical signal by modulating and restoring the polarization state, thereby improving the quality and intensity of the optical signal. In addition, the above design not only helps to reduce the number of optical components in the optical isolator, reducing the difficulty and cost of assembly, but also helps to enhance the optical isolator's ability to adapt to different working conditions and light sources.

[0066] Reference Figures 4 to 7 In one embodiment, the optical isolator further includes an incident element 300, a polarizer 400, and a receiving element 500, wherein the incident element 300, the polarizer 400, the optical rotator 200, and the magneto-optical component 100 are spaced apart along a first preset direction; the incident element 300 can emit polarized light toward the polarizer 400; the polarizer 400 can convert the polarized light into a first preset polarized light and a second preset polarized light, and can allow the first preset polarized light to pass through and can reflect the second preset polarized light, and the polarization state of the second preset polarized light differs from the polarization state of the first preset polarized light by 90°.

[0067] The receiving element 500 is located on the side of the polarizing element 400 away from the magneto-optical component 100 and spaced apart from the incident element 300 along a second predetermined direction, with the second predetermined direction forming an angle with the first predetermined direction. The receiving element 500 is capable of receiving polarized light that sequentially passes through the first light-transmitting film 111, the second light-transmitting film 112, and the polarizing element 400. The optical rotator 200 allows polarized light incident from the side of the optical rotator 200 closer to the magneto-optical component 100 to pass through and rotates the polarization state of the polarized light by a predetermined angle along the first direction. In this embodiment, the incident element 300 is a collimator, the polarizing element 400 is a polarizing prism, and the receiving element 500 is also a collimator. The second predetermined direction is perpendicular to the first predetermined direction. In other embodiments, the polarizing element 400 may alternatively be a polarizer or a fiber polarizer.

[0068] When the optical isolator of the present application demonstrates forward transmission, the incident element 300 emits polarized light toward the polarizer 400. Under the action of the polarizer 400, the polarization state of the polarized light is converted into polarized light with a polarization state of 0° and polarized light with a polarization state of 90°. The polarized light with a polarization state of 0° passes through the polarizer 400 and propagates toward the optical rotator 200, while the polarized light with a polarization state of 90° is reflected by the polarizer 400. The polarized light with a polarization state of 0° becomes the first preset polarized light, and the polarized light with a polarization state of 90° becomes the second preset polarized light. The polarized light with a polarization state of 0° then passes through the optical rotator 200, during which the polarization state of the polarized light rotates 45° counterclockwise. The polarized light then passes through the first light-transmitting film 111 and propagates toward the first reflective film 121, and is emitted from the second light-transmitting film 112 to the outside of the magneto-optical component 100. During this process, the polarization state of the polarized light rotates 45° clockwise and returns to 0°. Finally, the polarized light passes through the polarizer 400 and is received by the receiving element 500, thereby realizing the forward transmission function of the optical isolator.

[0069] When the optical isolator of the present application demonstrates reverse isolation, the receiving element 500 emits polarized light as reverse light or returned light toward the polarizer 400. The polarization state of the polarized light is converted into polarized light with a polarization state of 0° and a polarization state of 90° under the action of the polarizer 400. The polarized light with a polarization state of 0° in the polarized light passes through the polarizer 400 and propagates toward the second light-transmitting film 112. The polarized light with a polarization state of 90° is reflected by the polarizer 400. The polarized light with a polarization state of 0° is formed as the first preset polarized light, and the polarized light with a polarization state of 90° is formed as the second preset polarized light. The polarized light with a polarization state of 0° then passes through the second transparent film 112 and propagates toward the first reflective film 121. It is then emitted from the first transparent film 111 and out of the magneto-optical component 100. During this process, the polarization state of the polarized light is reversed by 45° clockwise. The polarized light then passes through the optical rotator 200. During this process, the polarization state of the polarized light continues to rotate by 45° clockwise, resulting in a polarization state of 90° (i.e., an "I" shape). Finally, the polarized light is reflected by the polarizer 400, preventing it from entering the incident element 300, thereby achieving the reverse isolation function of the optical isolator.

[0070] The incident element 300, polarizer 400 and receiver 500 used in this application can not only enable the optical isolator to achieve the forward passage function, but also enable the optical isolator to achieve the reverse isolation function, thereby ensuring the unidirectional propagation of light, improving signal quality, and enhancing the overall performance of the optical isolator. The incident element 300 is set up to collimate the light beam into parallel light, ensuring that the light signal enters the subsequent optical element in a stable polarization state, laying the foundation for the effective transmission of light. The receiver 500 is set up to not only receive polarized light, but also collimate the received polarized light into parallel light.

[0071] In addition, the design in which the first light-transmitting film 111 and the second light-transmitting film 112 are both arranged on the light-incident surface 110 enables the incident element 300 and the receiving element 500 to be located on the same side of the magneto-optical component 100, thereby helping to shorten the overall length of the optical isolator.

[0072] Reference Figure 8 and Figure 9 In one embodiment, the optical isolator further includes a filter 600, which is located between the incident element 300 and the polarizer 400, and between the receiving element 500 and the polarizer 400; the filter 600 covers the incident element 300 and the receiving element 500, and is capable of allowing polarized light to pass through.

[0073] In this embodiment, the filter 600 is a zero-degree polarizer. The filter 600 can effectively filter out stray light from polarized light, effectively improving the isolation of the optical isolator. In other embodiments, the filter 600 can also be a half-wave plate, a quarter-wave plate, or a fiber polarizer.

[0074] Reference Figure 10 and Figure 11 In one embodiment, the polarizer 400 includes a first polarizing prism 410 and a second polarizing prism 420 . The first polarizing prism 410 covers the first light-transmitting film 111 . The second polarizing prism 420 is located on one side of the first polarizing prism 410 and covers the second light-transmitting film 112 .

[0075] In this embodiment, the second polarizing prism 420 is spaced apart from the first polarizing prism 410 along the second predetermined direction. This design effectively reduces the manufacturing difficulty and cost of the polarizer 400. Furthermore, to further reduce the manufacturing difficulty and cost of the polarizer 400, the first polarizing prism 410 and the second polarizing prism 420 have the same structure. In other embodiments, the structures of the first polarizing prism 410 and the second polarizing prism 420 may also differ.

[0076] Reference Figure 10 and Figure 11 In one embodiment, the optical filter 600 includes a first zero-degree polarizer 610, which is positioned between the incident element 300 and the polarizer 400. The first zero-degree polarizer 610 covers the incident element 300 and allows polarized light to pass through. This design not only effectively filters out stray light from polarized light, but also helps reduce the manufacturing difficulty and cost of the optical filter 600.

[0077] Reference Figure 10 and Figure 11In one embodiment, the filter 600 further includes a second zero-degree polarizer 620 , which is located between the receiving element 500 and the polarizer 400 . The second zero-degree polarizer 620 covers the receiving element 500 and allows polarized light to pass through.

[0078] In this embodiment, the second zero-degree polarizer 620 is spaced apart from the first zero-degree polarizer 610 along the second predetermined direction. This design not only effectively filters stray light from polarized light but also helps reduce the manufacturing difficulty and cost of the filter element 600. Furthermore, to further reduce the manufacturing difficulty and cost of the polarizer 400, the first zero-degree polarizer 610 and the second zero-degree polarizer 620 have the same structure. In other embodiments, the structures of the first zero-degree polarizer 610 and the second zero-degree polarizer 620 may differ.

[0079] Reference Figure 10 and Figure 11 In one embodiment, the optical isolator further includes a light baffle 700. The first zero-degree polarizer 610, the first polarizing prism 410, and the optical rotator 200 are located on a first side of the light baffle 700. The second zero-degree polarizer 620 and the second polarizing prism 420 are located on a second side of the light baffle 700, with the first and second sides facing each other. The light baffle 700 effectively blocks the passage of light, reduces the crosstalk effect of stray light, and effectively improves the performance of the optical isolator.

[0080] Reference Figures 12 to 17 According to another aspect of the present application, embodiments of the present application further provide an optical circulator, comprising a first optical rotator and the aforementioned Faraday rotator; the first optical rotator is located on the side of the light incident surface away from the reflective surface and is covered with a first light-transmitting film. The first optical rotator is capable of transmitting polarized light incident from the side of the first optical rotator away from the magneto-optical component and rotating the polarization state of the polarized light by a predetermined angle along a second direction, the second direction being opposite to the first direction.

[0081] In this embodiment, the first optically active component 800 is an optically active crystal, which is a 22.5° half-wave plate or a component made of any one of quartz, sodium calcium aluminum silicate (NaCaAlSiO4), and magnesium aluminum spinel (MgAl2O4). In addition, the optically active crystal is placed only in the upper half of the central axis of the crystal.

[0082] In a specific embodiment, polarized light with a polarization state of 0° (i.e., a straight line) is incident on the first optical rotating component 800 from the side away from the magneto-optical component 100 toward the first optical rotating component 800 and passes through the first optical rotating component 800. During this process, the polarization state of the polarized light rotates 45° counterclockwise. The polarized light then passes through the first light-transmitting film 111 and propagates toward the first reflective film 121. Finally, the polarized light is emitted from the second light-transmitting film 112 to the outside of the magneto-optical component 100. During this process, the polarization state of the polarized light rotates 45° clockwise, at which point the polarization state of the polarized light returns to 0°.

[0083] The first optical rotation component 800 and the Faraday rotator used in conjunction with each other in the present application can not only restore the polarization state of polarized light to ensure the integrity of the optical signal, but also reduce the attenuation and distortion of the optical signal by modulating and restoring the polarization state, thereby improving the quality and intensity of the optical signal. In addition, the above design not only helps to reduce the number of optical components in the optical circulator, reducing the difficulty and cost of assembly, but also helps to enhance the ability of the optical circulator to adapt to different working conditions and light sources.

[0084] Reference Figures 12 to 17 In one embodiment, the optical circulator further includes a first collimator 900, a second collimator 1000, a third collimator 1100, a polarization component 1200, and a second optical rotation component 1300, wherein the first collimator 900, the polarization component 1200, the first optical rotation component 800, and the magneto-optical component 100 are arranged at intervals along a first preset direction.

[0085] The first collimator 900 can emit polarized light toward the polarization component 1200; the polarization component 1200 can convert the polarized light into a first preset polarized light and a second preset polarized light, and can allow the first preset polarized light to pass through and can reflect the second preset polarized light, and the polarization state of the second preset polarized light differs by 90° from the polarization state of the first preset polarized light.

[0086] The second collimator 1000 is located on a side of the polarization component 1200 away from the magneto-optical component 100 and is spaced apart from the first collimator 900 along a second preset direction, with the second preset direction forming an angle with the first preset direction. The second collimator 1000 is capable of receiving polarized light that sequentially passes through the first light-transmitting film 111, the second light-transmitting film 112, and the polarization component 1200. The first optical rotation component 800 is capable of allowing polarized light incident on the side of the first optical rotation component 800 closer to the magneto-optical component 100 to pass through, and is capable of rotating the polarization state of the polarized light by a preset angle along the first direction.

[0087] The third collimator 1100, the second optical rotation component 1300 and the polarization component 1200 are arranged at intervals along the second preset direction; the third collimator 1100 can receive polarized light that passes through the second light-transmitting film 112, the first light-transmitting film 111, the first optical rotation component 800, the polarization component 1200 and the second optical rotation component 1300 in sequence.

[0088] The second optical rotator component 1300 allows polarized light incident from the side of the second optical rotator component 1300 close to the polarization component 1200 to pass through, and can rotate the polarization state of the polarized light along a second turn by an angle twice the preset angle, where the second turn is opposite to the first turn. The second optical rotator component 1300 can also allow polarized light incident from the side of the second optical rotator component 1300 close to the third collimator 1100 to pass through, and can rotate the polarization state of the polarized light along the first turn by an angle twice the preset angle.

[0089] In this embodiment, the polarization component 1200 is a polarizing prism, and the second optical rotation component is a 45° half-wave plate or an optical rotation crystal made of any of quartz, sodium calcium aluminum silicate (NaCaAlSiO4), and magnesium aluminum spinel (MgAl2O4). The second predetermined direction is perpendicular to the first predetermined direction. In other embodiments, the polarization component 1200 may also be a polarizing plate or a fiber polarizer.

[0090] In the optical circulator of the present application, when light is incident on the first collimator 900 and received by the second collimator 1000 in the forward direction, the first collimator 900 emits polarized light toward the polarization component 1200. The polarization state of the polarized light is converted into polarized light with a polarization state of 0° and polarized light with a polarization state of 90° by the polarization component 1200. The polarized light with a polarization state of 0° passes through the polarization component 1200 and propagates toward the first optical rotation component 800, while the polarized light with a polarization state of 90° is reflected by the polarization component 1200. The polarized light with a polarization state of 0° becomes the first preset polarized light, and the polarized light with a polarization state of 90° becomes the second preset polarized light. The polarized light with a polarization state of 0° then passes through the first optical rotation component 800, during which the polarization state of the polarized light rotates 45° counterclockwise. The polarized light then passes through the first light-transmitting film 111 and propagates toward the first reflective film 121, and is emitted from the second light-transmitting film 112 to the outside of the magneto-optical component 100. During this process, the polarization state of the polarized light rotates 45° clockwise and returns to 0°. Finally, the polarized light passes through the polarization component 1200 and is received by the second collimator 1000, thereby realizing the forward passage function of the optical circulator.

[0091] In the optical circulator demonstration of the present application, when the second collimator 1000 is incident and the third collimator 1100 receives this forward passage, the second collimator 1000 emits polarized light toward the polarization component 1200. The polarization state of the polarized light is converted into polarized light with a polarization state of 0° and a polarization state of 90° under the action of the polarization component 1200. The polarized light with a polarization state of 0° in the polarized light passes through the polarization component 1200 and propagates toward the second light-transmitting film 112, and the polarized light with a polarization state of 90° is reflected by the polarization component 1200; the polarized light with a polarization state of 0° forms the first preset polarized light, and the polarized light with a polarization state of 90° forms the second preset polarized light. The polarized light with a polarization state of 0° then passes through the second transparent film 112 and propagates toward the first reflective film 121. It is then emitted from the first transparent film 111 and out of the magneto-optical component 100, during which its polarization state is reversed 45° clockwise. The polarized light then passes through the first optical rotator component 800, during which its polarization state is further rotated 45° clockwise, resulting in a polarization state of 90° (i.e., an "I" shape). Finally, the polarized light is reflected by the polarization component 1200 toward the second optical rotator component 1300. The polarized light with a polarization state of 90° passes through the second optical rotator component 1300, during which its polarization state is rotated 90° counterclockwise and returned to 0°, allowing it to be received by the third collimator 1100, thereby achieving the forward transmission function of the optical circulator.

[0092] When the optical circulator of the present application demonstrates reverse isolation, the third collimator 1100 emits polarized light as reverse light or return light toward the second optical rotation component 1300. At this time, the polarization state of the polarized light is 0°. The polarized light passes through the second optical rotation component 1300. During this process, the polarization state of the polarized light rotates 90° clockwise. Subsequently, the polarized light with a polarization state of 90° is emitted toward the polarization component 1200 and, after being reflected by the polarization component 1200, is emitted toward the first optical rotation component 800. The polarized light with a polarization state of 90° then passes through the first optical rotation component 800. During this process, , the polarization state of the polarized light rotates 45° counterclockwise; then the polarized light passes through the first light-transmitting film 111 and propagates toward the first reflective film 121, and is emitted from the second light-transmitting film 112 to the outside of the magneto-optical component 100. During this process, the polarization state of the polarized light rotates 45° clockwise and recovers to 90°; finally, the polarization state is 90° and is emitted toward the polarization component 1200. After being reflected by the polarization component 1200, the polarized light is emitted toward the second optical rotation component 1300, so that the polarized light does not enter the second collimator 1000, thereby realizing the reverse isolation function of the optical circulator.

[0093] The first collimator 900, the second collimator 1000, the third collimator 1100, the polarization component 1200, and the second optical rotation component 1300 used in conjunction with each other in the present application can not only enable the optical circulator to achieve a forward passage function, but also enable the optical circulator to achieve a reverse isolation function, thereby ensuring unidirectional propagation of light, improving signal quality, and enhancing the overall performance of the optical circulator.

[0094] In summary, the Faraday rotator, optical isolator, and optical circulator provided in this embodiment have at least the following beneficial technical effects: when the Faraday rotator of the present application rotates the polarization state of polarized light, the polarized light propagating toward the first reflective film 121 first passes through one of the first light-transmitting film 111 and the second light-transmitting film 112. The polarized light is reflected by the first reflective film 121 toward the other of the first light-transmitting film 111 and the second light-transmitting film 112, and passes through the other to be emitted outside the magneto-optical component 100, thereby extending the propagation path of the polarized light within the magneto-optical component 100. The optical rotation angle is not only positively correlated with the magnetic field intensity, but also positively correlated with the propagation length of the polarized light in the magneto-optical component 100. The magneto-optical component 100 provided with the first light-transmitting film 111, the second light-transmitting film 112 and the first reflective film 121 in the present application can reflect the polarized light in the magneto-optical component 100, thereby extending the propagation path of the polarized light in the magneto-optical component 100. This design enables the Faraday rotator to achieve the original effect while reducing the size of the magnetic field generating component, which helps to reduce the overall size of the Faraday rotator and thus helps to miniaturize the Faraday rotator.

[0095] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A Faraday rotator, characterized in that: The device comprises a magneto-optical component and a magnetic field applying member, wherein the magnetic field applying member is capable of applying an external magnetic field to the magneto-optical component; the magneto-optical component is capable of rotating the polarization state of polarized light along a first direction by a preset angle in the external magnetic field, wherein the preset angle is formed as an optical rotation angle; The magneto-optical component has a light incident surface and a reflective surface that are arranged opposite to each other, the light incident surface is provided with a first light-transmitting film and a second light-transmitting film in sequence, and the reflective surface is provided with a first reflective film; The first light-transmitting film and the second light-transmitting film are both capable of allowing the polarized light propagating toward the first reflective film to pass therethrough, the first reflective film is capable of reflecting the polarized light toward the first light-transmitting film or the second light-transmitting film, and the first light-transmitting film and the second light-transmitting film are both capable of allowing the polarized light to pass therethrough and be emitted out of the magneto-optical component; When one of the first light-transmitting film and the second light-transmitting film transmits the polarized light traveling toward the first reflective film, the other transmits the polarized light to emit it outside the magneto-optical component.

2. The Faraday rotator according to claim 1, wherein A second reflective film is further provided on the light incident surface, the second reflective film being located between the first light-transmitting film and the second light-transmitting film and capable of reflecting the polarized light toward the first reflective film; The first reflective film can reflect the polarized light toward the second reflective film, and can finally reflect the polarized light toward the first light-transmitting film or the second light-transmitting film.

3. An optical isolator, characterized in that: The device comprises an optical rotator and the Faraday rotator according to claim 1 or 2; the optical rotator is located on a side of the light incident surface away from the reflective surface and covers the first light-transmitting film; The optical rotator can allow polarized light incident from a side of the optical rotator away from the magneto-optical component to pass through, and can rotate the polarization state of the polarized light by the preset angle along a second direction, which is opposite to the first direction.

4. The optical isolator according to claim 3, wherein: The optical isolator further comprises an incident element, a polarizing element and a receiving element, wherein the incident element, the polarizing element, the optical rotator and the magneto-optical component are arranged at intervals along a first preset direction; The incident element is capable of emitting polarized light toward the polarizer; the polarizer is capable of converting the polarized light into a first preset polarized light and a second preset polarized light, and is capable of allowing the first preset polarized light to pass through and reflecting the second preset polarized light, wherein the polarization state of the second preset polarized light differs from the polarization state of the first preset polarized light by 90°; The receiving element is located on a side of the polarizing element away from the magneto-optical component and is spaced apart from the incident element along a second preset direction, and an angle is formed between the second preset direction and the first preset direction; the receiving element is capable of receiving polarized light that passes through the first light-transmitting film, the second light-transmitting film, and the polarizing element in sequence; the optical rotator is capable of allowing polarized light incident from a side of the optical rotator close to the magneto-optical component to pass through, and is capable of rotating the polarization state of the polarized light along the first direction by the preset angle.

5. The optical isolator according to claim 4, wherein: The polarizer includes a first polarizing prism and a second polarizing prism. The first polarizing prism covers the first light-transmitting film. The second polarizing prism is located on one side of the first polarizing prism and covers the second light-transmitting film.

6. The optical isolator according to claim 5, wherein: The optical isolator further includes a filter element, which is located between the incident element and the polarizing element and between the receiving element and the polarizing element; the filter element covers the incident element and the receiving element and is capable of allowing polarized light to pass through.

7. The optical isolator according to claim 6, wherein: The optical filter comprises a first zero-degree polarizer, the first zero-degree polarizer being located between the incident element and the polarizer, the first zero-degree polarizer covering the incident element and capable of allowing polarized light to pass through; The optical filter further includes a second zero-degree polarizer located between the receiving element and the polarizer. The second zero-degree polarizer covers the receiving element and is capable of allowing polarized light to pass through.

8. The optical isolator according to claim 7, wherein: The optical isolator further includes a light barrier, wherein the first zero-degree polarizer, the first polarizing prism, and the optical rotator are located on a first side of the light barrier, and the second zero-degree polarizer and the second polarizing prism are located on a second side of the light barrier, wherein the first side and the second side are arranged opposite to each other; and / or The first zero-degree polarizer and the second zero-degree polarizer have the same structure; and / or, The first polarizing prism and the second polarizing prism have the same structure.

9. An optical circulator, characterized in that: The Faraday rotator comprises a first optical rotation component and the Faraday rotator according to claim 1 or 2; the first optical rotation component is located on a side of the light incident surface away from the reflective surface and covers the first light-transmitting film; The first optical rotation component can allow polarized light incident from a side of the first optical rotation component away from the magneto-optical component to pass through, and can rotate the polarization state of the polarized light by the preset angle along a second direction, which is opposite to the first direction.

10. The optical circulator according to claim 9, characterized in that: The optical circulator further includes a first collimator, a second collimator, a third collimator, a polarization component, and a second optical rotation component, wherein the first collimator, the polarization component, the first optical rotation component, and the magneto-optical component are arranged at intervals along a first preset direction; The first collimator is capable of emitting polarized light toward the polarization component; the polarization component is capable of converting the polarized light into a first preset polarized light and a second preset polarized light, and is capable of allowing the first preset polarized light to pass and reflecting the second preset polarized light, wherein the polarization state of the second preset polarized light differs from the polarization state of the first preset polarized light by 90°; The second collimator is located on a side of the polarization component away from the magneto-optical component and is spaced apart from the first collimator along a second preset direction, with the second preset direction forming an angle with the first preset direction. The second collimator is capable of receiving polarized light that sequentially passes through the first light-transmitting film, the second light-transmitting film, and the polarization component. The first optical rotation component is capable of allowing polarized light incident on a side of the first optical rotation component close to the magneto-optical component to pass through, and is capable of rotating the polarization state of the polarized light by the preset angle along the first direction. The third collimator, the second optical rotation component, and the polarization component are arranged at intervals along the second preset direction; the third collimator is capable of receiving polarized light that passes through the second light-transmitting film, the first light-transmitting film, the first optical rotation component, the polarization component, and the second optical rotation component in sequence; The second optical rotator component is capable of allowing polarized light incident from a side of the second optical rotator component close to the polarization component to pass therethrough, and is capable of rotating the polarization state of the polarized light along a second turn by an angle twice the preset angle, wherein the second turn is opposite to the first turn. The second optical rotator component is also capable of allowing polarized light incident from a side of the second optical rotator component close to the third collimator to pass therethrough, and is capable of rotating the polarization state of the polarized light along the first turn by an angle twice the preset angle.

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