A co-located circulator and method of making the same

Abstract

The application discloses a same-side circulator and a preparation method thereof. The same-side circulator sequentially comprises a multi-core tail fiber, a polarization beam splitting prism, a first optical rotation unit, a collimating lens, a second optical rotation unit, a Wollaston prism and a mirror. The first optical rotation unit comprises a first half-wave group and a second half-wave group. First port exit light sequentially passes through the polarization beam splitting prism, the first half-wave group, the collimating lens, the second optical rotation unit and the Wollaston prism to reach the mirror, and after reflection, sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the first optical rotation unit and the polarization beam splitting prism. Second port exit light sequentially passes through the polarization beam splitting prism, the first optical rotation unit, the collimating lens, the second optical rotation unit and the Wollaston prism to reach the mirror, and after reflection, sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the first half-wave group and the polarization beam splitting prism. The application can improve reliability and miniaturization, and can be widely applied to the technical field of optical devices.

Description

Technical Field

[0001] This application relates to the field of optical device technology, and in particular to a same-side circulator and its fabrication method. Background Technology

[0002] See Figure 1 A typical optical circulator has three ports: Port1, Port2, and Port3. Optical signals from Port1 pass through the circulator to Port2, and from Port2 to Port3. Optical signals from Port3 do not pass through the circulator, thus forming a non-blocking circular transmission of optical signals. Therefore, an optical circulator is a non-reciprocal passive optical device, widely used in single-fiber bidirectional transmission systems. In related technologies, the miniaturization and reliability of same-side circulators need further improvement. Summary of the Invention

[0003] The main objective of this application is to propose a same-side circulator and its fabrication method, which aims to improve reliability and miniaturization.

[0004] To achieve the above objectives, one aspect of this application proposes a same-side circulator, which sequentially includes a multi-core pigtail, a polarizing beam splitter, a first optical rotation unit, a collimating lens, a second optical rotation unit, a Wollaston prism, and a reflector. The first optical rotation unit includes a first half-wave group and a second half-wave group. Light emitted from the first port of the multi-core pigtail sequentially passes through the polarizing beam splitter, the first half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to reach the reflector, and after being reflected by the reflector, sequentially passes through the Wollaston prism and the second optical rotation unit. The optical unit, the collimating lens, the second half-wave group, the first half-wave group, and the polarizing beam splitter are emitted from the second port of the multi-core pigtail. The light emitted from the second port of the multi-core pigtail passes sequentially through the polarizing beam splitter, the first half-wave group, the second half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to reach the reflecting mirror. After being reflected by the reflecting mirror, the light passes sequentially through the Wollaston prism, the second optical rotation unit, the collimating lens, the first half-wave group, and the polarizing beam splitter, and is emitted from the third port of the multi-core pigtail.

[0005] In some embodiments, the leading edge of the multi-core pigtail is coated with an anti-reflection film and ground to a preset angle.

[0006] In some embodiments, the first half-wave group includes two 22.5° optical axis half-wave plates, which are arranged side by side and mirror symmetrically. The second half-wave group includes a 45° optical axis half-wave plate, which is arranged at a preset position of the first half-wave group and does not fully cover it.

[0007] In some embodiments, the collimating lens includes a spherical lens or a graduated refractive index lens.

[0008] In some embodiments, the second optical rotation unit includes a Faraday optical rotation plate.

[0009] In some embodiments, the Wollaston prism comprises two wedge-shaped plates with their optical axes perpendicular to each other.

[0010] In some embodiments, the tilt angle of the reflector is determined based on the tilt angle of the first port and the tilt angle of the second port.

[0011] In some embodiments, the deflection angle of the Wollaston prism is determined based on the tilt angle of the reflector, the tilt angle of the second port, and the tilt angle of the third port.

[0012] To achieve the above objectives, another aspect of this application provides a method for preparing a same-side circulator, comprising: The polarizing beam splitter is fixed to the front end face of the multi-core pigtail. The first optical rotation unit is fixed on the surface of the polarizing beam splitter; The relative position between the multi-core pigtail and the collimating lens is fixed, with the front end face of the multi-core pigtail located at the rear focal point of the collimating lens; The second optical rotation unit and the Wollaston prism are attached and fixed inside the magnetic ring. The Wollaston prism is fixed through one side of the magnetic ring so that the optical axis of the Wollaston prism is aligned with the polarization state of the collimated beam. Adjust the tilt angle of the reflector to minimize insertion loss and fix the other side of the magnetic ring.

[0013] The embodiments of this application include at least the following beneficial effects: This application provides a same-side circulator and its preparation method. The same-side circulator sequentially includes a multi-core pigtail, a polarizing beam splitter, a first optical rotation unit, a collimating lens, a second optical rotation unit, a Wollaston prism, and a reflector. The first optical rotation unit includes a first half-wave group and a second half-wave group. The light emitted from the first port of the multi-core pigtail sequentially passes through the polarizing beam splitter, the first half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to reach the reflector. After being reflected by the reflector, it sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the second half-wave group, the first half-wave group, and the polarizing beam splitter, and is emitted from the second port of the multi-core pigtail. The light emitted from the second port of the multi-core pigtail sequentially passes through a polarizing beam splitter, a first half-wave group, a second half-wave group, a collimating lens, a second optical rotation unit, and a Wollaston prism before reaching the reflecting mirror. After being reflected by the reflecting mirror, it sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the first half-wave group, and the polarizing beam splitter before exiting from the third port of the multi-core pigtail. By placing the polarizing beam splitter and the first optical rotation unit before the collimating lens, some components are moved forward, effectively reducing the size of the same-side circulator and facilitating miniaturization. The two beams emitted from the polarizing beam splitter achieve complementary optical path exchange after reflection by the reflecting mirror, reducing polarization mode dispersion and improving the performance and reliability of the same-side circulator. Attached Figure Description

[0014] Figure 1 This is an optical path diagram of an optical circulator in the related technology provided in the embodiments of this application; Figure 2 This is a side sectional view of a same-side annulus provided in an embodiment of this application; Figure 3 This is a side sectional view of another same-side annulus provided in an embodiment of this application; Figure 4 This is the optical path diagram of the polarizing beam splitter provided in the embodiments of this application; Figure 5 This is the optical path diagram of the half-wave plate provided in the embodiments of this application; Figure 6 This is a structural diagram of the first optical rotation unit provided in the embodiments of this application; Figure 7 This is the optical path diagram of the collimating lens provided in the embodiments of this application; Figure 8 This is the optical path diagram of the second optical rotation unit provided in the embodiments of this application; Figure 9 This is a structural and optical path diagram of the Wollaston prism provided in an embodiment of this application; Figure 10 This is an optical path diagram from the first port to the second port provided in an embodiment of this application; Figure 11This is the optical path diagram from the second port to the third port provided in the embodiments of this application; Figure 12 This is a polarization state change diagram from the first port to the second port provided in an embodiment of this application; Figure 13 This is a polarization state change diagram from the second port to the third port provided in an embodiment of this application; Figure 14 This is a flowchart of the method for preparing the same-side circulator provided in the embodiments of this application. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0016] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0017] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0019] See Figure 2 and Figure 3This application provides a same-side circulator, which sequentially includes a multi-core fiber optic cable 1-1, a polarizing beam splitter 1-2, a first optical rotation unit 1-3, a collimating lens 1-4, a second optical rotation unit 1-5, a Wollaston prism 1-6, and a reflector 1-7. The first optical rotation unit 1-3 includes a first half-wave group and a second half-wave group. Light emitted from the first port (Port1) of the multi-core fiber optic cable 1-1 passes sequentially through the polarizing beam splitter 1-2, the first half-wave group, the collimating lens 1-4, the second optical rotation unit 1-5, and the Wollaston prism 1-6 to reach the reflector 1-7. After being reflected by the reflector 1-7, it passes sequentially through the Wollaston prism 1-6 and the second optical rotation unit 1-5. The collimating lens 1-4, the second half-wave group, the first half-wave group, and the polarizing beam splitter 1-2 exit from the second port (Port2) of the multi-core pigtail 1-1. The light emitted from the second port (Port2) of the multi-core pigtail 1-1 passes sequentially through the polarizing beam splitter 1-2, the first half-wave group, the second half-wave group, the collimating lens 1-4, the second optical rotation unit 1-5, and the Wollaston prism 1-6 to reach the reflecting mirror 1-7. After being reflected by the reflecting mirror 1-7, the light passes sequentially through the Wollaston prism 1-6, the second optical rotation unit 1-5, the collimating lens 1-4, the first half-wave group, and the polarizing beam splitter 1-2, and exits from the third port (Port3) of the multi-core pigtail 1-1.

[0020] In some embodiments, the leading edge of the multi-core pigtail is coated with an anti-reflection film and ground to a preset angle.

[0021] Multi-core pigtails mainly carry all input and output ports of optical signals. The front end is coated with an anti-reflection film and ground to a preset tilt angle, usually 8°, which reduces reflection and improves the product's return loss parameters.

[0022] See Figure 4 The main function of a polarizing beam splitter (PBS) is to separate natural light into two linearly polarized beams (P-beam and S-beam) with mutually perpendicular polarization states at a predetermined distance d. In some embodiments, the first half-wave group includes two half-wave plates with an optical axis of 22.5°, which are arranged side by side and mirror-symmetrical. The second half-wave group includes a half-wave plate with an optical axis of 45°, which is located at a preset position of the first half-wave group and does not fully cover it.

[0023] The first half-wave group consists of two half-wave plates with an optical axis of 22.5°, and the second half-wave group consists of one half-wave plate with an optical axis of 45°. The first and second half-wave groups together form the first optical rotation unit, enabling reciprocal conversion of the polarization state of the optical signal.

[0024] See Figure 5A half-wave plate is a reciprocal crystal, and its function is to reciprocally rotate the polarization direction of linearly polarized light. When linearly polarized light is incident perpendicularly on a half-wave plate, if the angle between the polarization direction of the incident light and the optical axis of the half-wave plate is A, the transmitted light is still linearly polarized light, and its polarization direction is rotated about the optical axis by an angle of 2A (when A=22.5°, the polarization direction is rotated by 45°; when A=45°, the polarization direction is rotated by 90°).

[0025] See Figure 6 In (a), two 22.5° half-wave plates are placed side by side to form a half-wave plate group. The optical axes of the two wave plates are at 22.5° with the y-axis and are mirror images of each other. Their function is to rotate the polarization direction of the incident ray polarized light by 45°. When two beams of polarized light with mutually perpendicular polarization states pass through the first half-wave group (when one beam passes through one of the wave plates, the other beam passes through the other half-wave plate), the polarization states of the two beams of polarized light can be transformed into parallel polarization states.

[0026] See Figure 6 In (b), a 45° half-wave plate is then placed at 1 / 3 of the total area of ​​the half-wave plate group, thus stacking them into the first optical rotation unit.

[0027] In some embodiments, the collimating lens includes a spherical lens or a graded-index lens.

[0028] Collimating lenses can be spherical lenses (C-LENS) or graded-index lenses (Grin-LENS). Their function is to collimate a rapidly diverging Gaussian beam in free space (unconstrained) into a slower-diverging Gaussian beam, thereby achieving collimation of the optical signal.

[0029] See Figure 7 The distance d between the fiber core and the horizontal central axis means that the light emitted from the fiber will form a certain crossing angle A with the horizontal central axis after being collimated by a collimating lens (taking C-LENS as an example, with curvature R and material refractive index n). The relationship between the crossing angle and the fiber core distance is determined by the following formula (Note: The expression for the crossing angle varies depending on the type of lens; this example only uses the commonly used C-LENS collimating lens).

[0030] For the circulator of this application, each port is spatially separate and non-overlapping, and the distance d between each fiber and the horizontal central axis is not consistent. Therefore, for each port, there will be three intersection angles when the light exits through the collimator lens.

[0031] Taking a three-port circulator as an example, assuming that the distances d1 / d2 / d3 of the ports Port1 / Port2 / Port3 to the horizontal central axis are A1 / A2 / A3 respectively, the intersection angles with the horizontal central axis after collimation are A1 / A2 / A3.

[0032] In some embodiments, the second optical rotator includes a Faraday rotator.

[0033] See Figure 8 The second optical rotator unit is mainly a Faraday rotator, which is a non-reciprocal crystal. Its function is to non-reciprocally rotate the polarization direction of linearly polarized light. That is, the rotation direction of the polarization state is independent of the propagation direction of the light and only depends on the direction of the applied magnetic field. When a saturated magnetic field N→S along the positive Z-axis is applied to the rotator, the polarization direction of the linearly polarized light passing through this unit will rotate counterclockwise in the XY plane (generally satisfying the right-hand screw rule).

[0034] In some embodiments, the Wollaston prism includes two wedge-shaped plates with their optical axes perpendicular to each other.

[0035] The Wollaston prism is composed of two wedge plates with mutually perpendicular optical axes. The material is a birefringent crystal, and the wedge angle is a predetermined design angle. Its function is to separate the incident natural light into two beams of linearly polarized light with mutually perpendicular polarization directions at a certain angle. With the polarization state control of the first and second optical rotation units, non-reciprocal deflection of the optical signal can be achieved.

[0036] See Figure 9 In (a), the red arrow indicates the optical axis direction of the wedge plate. The wedge angles are defined by the following parameters: the optical axis of the first wedge is parallel to the Y-axis, and the X-axis of the second wedge is parallel to the Y-axis. (See also...) Figure 9 In (b), when linearly polarized light enters from the first wedge and its polarization direction is parallel to the optical axis of the first wedge, the outgoing beam will undergo a change compared to the incident light. Angular deflection (a clockwise deflection of the output light relative to the input fiber is indicated by a positive sign). See also Figure 9 In (c), when linearly polarized light enters from the first wedge plate and its polarization direction is perpendicular to the optical axis of the first wedge plate, the outgoing beam will undergo a change compared to the incident light. Angular deflection (the output light beam deflects counterclockwise relative to the input fiber, indicated by a negative sign). See the two cases for reverse transmission. Figure 9 (d) and (e) in the text.

[0037] wedge plate wedge angle With deflection angle The relationship between them is determined by the following expression:

[0038] in, n o / n e ...

[0039] In some embodiments, the tilt angle of the reflector is determined based on the tilt angle of the first port and the tilt angle of the second port.

[0040] The main function of a plane mirror is to reflect light in the forward transmission path, thus folding the light signal back and forth. Light is deflected in the opposite direction after passing through the mirror, satisfying the relationship that the angle of incidence equals the angle of reflection. Since the angle of the mirror is adjustable, let the angle between the mirror and the vertical axis (i.e., the Y-axis) be... β .

[0041] In some embodiments, the deflection angle of the Wollaston prism is determined based on the tilt angle of the reflector, the tilt angle of the second port, and the tilt angle of the third port.

[0042] From Port1 to Port2, light rays exit from Port1, pass through the collimator lens to create an angle with the horizontal axis A1, and then enter the Wollaston prism through the second optical rotation unit, where they are deflected clockwise. The angle is then reflected by the mirror and deflected counterclockwise. Passing through Wollaston again, it now deflects clockwise, producing... The angle is then coupled to Port2 via a collimating lens.

[0043] Therefore, the mathematical relationship between the angles coupled from Port1 to Port2 is as follows:

[0044] That is, relation 1:

[0045] From Port2 to Port3, light rays exit from Port2, pass through the collimator lens to create an angle with the horizontal axis A2, and then enter the Wollaston prism through the second optical rotation unit, where they are deflected counterclockwise. The angle is then reflected by the mirror and deflected clockwise. Passing through Wollaston again, it now deflects counterclockwise, producing... The angle is then coupled to Port3 via a collimating lens.

[0046] Therefore, the mathematical relationship between the angles coupled from Port2 to Port3 is as follows:

[0047] That is, relation 2:

[0048] Once the positions of Port1 / 2 / 3 are determined, the corresponding angles A1 / A2 / A3 are also determined. Adjust the reflector angles, i.e. A value is selected such that relation 1 holds, enabling Port1→Port2 coupling. Subsequently, a suitable Wollaston prism angle is chosen. This makes relation 2 true, enabling Port2→Port3 coupling.

[0049] In this embodiment, the optical path of the circulator on the same side is as follows: See Figure 10 The optical signal originates from Port1 and passes sequentially through the PBS crystal → 22.5° half-wave plate group → collimating lens → Faraday rotator → Wollaston prism → mirror → Wollaston prism → Faraday rotator → collimating lens → 45° half-wave plate → 22.5° half-wave plate group → PBS crystal before entering Port2.

[0050] See Figure 11 The optical signal originates from Port2 and passes sequentially through the PBS crystal → 22.5° half-wave plate group → 45° half-wave plate → collimating lens → Faraday rotator → Wollaston prism → reflector → Wollaston prism → Faraday rotator → collimating lens → 22.5° half-wave plate group → PBS crystal before entering Port3.

[0051] If Port4 is added, the order in which the optical path from Port3 to Port4 passes through the crystal is the same as that from Port1 to Port2, only the port positions change, so it will not be elaborated further.

[0052] In this embodiment, the polarization state changes of the same-side circulator are as follows: random polarization of natural light is represented by a double-headed cross arrow, and linear polarization is represented by a single arrow.

[0053] See Figure 12 Randomly polarized light is emitted from Port 1. After passing through (1) the PBS crystal, it is separated into two linearly polarized beams with mutually perpendicular polarization states in the X direction. After passing through (2) the 22.5° half-wave plate group, the polarization directions of the two beams are the same and form a positive 45° angle with the XY plane. After being collimated by a lens, the two beams enter (3) the Faraday rotator, and the polarization directions of the two beams are aligned with the X direction. Then they enter (4) the Wollaston prism and the plane mirror. At this time, the polarization directions of the two beams are aligned with the first wedge plate in the Wollaston prism. The optical axes are aligned parallel to each other, and the optical axes of the second wedge plate are aligned perpendicularly. With the folding effect of the mirror, the beam is deflected in the Y-axis direction, resulting in a shift from position 1 to position 2. Then it enters the (5) Faraday rotator plate again, and the polarization directions of the two beams are the same and form a negative 45° angle with the XY plane. It enters the (6) 45-degree half-wave plate, and the polarization directions are the same and form a positive 45° angle with the XY plane. It enters the (7) 22.5° half-wave plate group, and the two polarized beams return to a state of mutual perpendicularity. It enters the (8) PBS crystal, and the beams are recombined and output at Port 2.

[0054] See Figure 13 Randomly polarized light is emitted from Port2. After passing through (1) the PBS crystal, it is separated into two linearly polarized beams with mutually perpendicular polarization states in the X direction. After passing through (2) the 22.5° half-wave plate group, the polarization directions of the two beams are the same and they form a positive 45° angle with the XY plane. After entering (3) the 45° half-wave plate, the polarization directions are the same and they form a negative 45° angle with the XY plane. After being collimated by a lens, the two beams of polarized light with the same polarization direction enter (4) the Faraday rotator plate, and the polarization directions of the two beams are aligned with the Y direction. Then they enter (5) the Wollaston prism and the plane. The polarization direction of the two polarized beams is perpendicularly aligned with the optical axis of the first wedge plate in the Wollaston prism, and the optical axis of the second wedge plate is horizontally aligned. With the folding effect of the mirror, the beams are deflected in the Y-axis direction, resulting in a shift from position 2 to position 3. Then, they enter the (6) Faraday rotator plate again, and the polarization direction of the two beams is the same and forms a positive 45° angle with the XY plane. They enter the (7) 22.5° half-wave plate group, and the two polarized beams return to a state of mutual perpendicularity. They enter the (8) PBS crystal, recombined, and output at Port 3.

[0055] See Figure 14 This application also provides a method for preparing a same-side circulator, used to prepare the above-mentioned same-side circulator, comprising: Step S101: Fix the polarizing beam splitter to the front end face of the multi-core pigtail. Step S102: Fix the first optical rotation unit on the surface of the polarizing beam splitter; Step S103: Fix the relative position between the multi-core pigtail and the collimating lens, with the front end face of the multi-core pigtail located at the rear focal point of the collimating lens; Step S104: The second optical rotation unit and the Wollaston prism are attached and fixed inside the magnetic ring. The Wollaston prism is fixed through one side of the magnetic ring so that the optical axis of the Wollaston prism is aligned with the polarization state of the collimated beam. Step S105: Adjust the tilt angle of the reflector to minimize insertion loss and fix the other side of the magnetic ring.

[0056] See Figure 14The overall structure of the device, from left to right, consists of a multi-core pigtail → PBS crystal → first optical rotation unit → collimating lens → second optical rotation unit → Wollaston prism → plane mirror. (1) The PBS crystal can be fixed to the front end of the multi-core pigtail by dispensing glue through a custom bracket or direct mounting. (2) The half-wave plates involved in the first optical rotation unit are attached to the surface of the PBS crystal one by one according to the aforementioned stacking rules and fixed by dispensing glue. (3) The multi-core pigtail with the crystal attached is fixed with a clamp, and its front end is placed at the back focal point of the collimating lens by a three-dimensional adjustment frame. The positions of the two can be fixed by dispensing glue through a glass tube sleeve. (4) The second optical rotation unit is attached to the Wollaston prism clip by dispensing glue, and then the four corners are fixed inside the magnetic ring by dispensing glue. The magnetic ring with the attached crystal is placed on the collimating lens at the magnetic ring opening on the side near the second optical rotation unit. The magnetic ring is rotated to align the optical axis of the Wollaston prism with the polarization state of the collimated beam and fixed by dispensing glue. (5) Connect the light source and power meter to each port of the device, adjust the plane mirror for coupling to minimize insertion loss, and seal it to the other side of the magnetic ring port with glue. This completes the assembly of the entire device.

[0057] The embodiments of this application include at least the following beneficial effects: This application provides a same-side circulator and its preparation method. The same-side circulator sequentially includes a multi-core pigtail, a polarizing beam splitter, a first optical rotation unit, a collimating lens, a second optical rotation unit, a Wollaston prism, and a reflector. The first optical rotation unit includes a first half-wave group and a second half-wave group. The light emitted from the first port of the multi-core pigtail sequentially passes through the polarizing beam splitter, the first half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to reach the reflector. After being reflected by the reflector, it sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the second half-wave group, the first half-wave group, and the polarizing beam splitter, and is emitted from the second port of the multi-core pigtail. The light emitted from the second port of the multi-core pigtail sequentially passes through a polarizing beam splitter, a first half-wave group, a second half-wave group, a collimating lens, a second optical rotation unit, and a Wollaston prism before reaching the reflecting mirror. After being reflected by the reflecting mirror, it sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, the first half-wave group, and the polarizing beam splitter before exiting from the third port of the multi-core pigtail. By placing the polarizing beam splitter and the first optical rotation unit before the collimating lens, some components are moved forward, effectively reducing the size of the same-side circulator and facilitating miniaturization. The two beams emitted from the polarizing beam splitter achieve complementary optical path exchange after reflection by the reflecting mirror, reducing polarization mode dispersion and improving the performance and reliability of the same-side circulator.

[0058] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0059] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion.

[0060] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0061] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A same-side annular device, characterized in that, The system comprises, in sequence, a multi-core pigtail, a polarizing beam splitter, a first optical rotation unit, a collimating lens, a second optical rotation unit, a Wollaston prism, and a reflector. The first optical rotation unit includes a first half-wave group and a second half-wave group. Light emitted from the first port of the multi-core pigtail sequentially passes through the polarizing beam splitter, the first half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to reach the reflector. After being reflected by the reflector, light then sequentially passes through the Wollaston prism, the second optical rotation unit, the collimating lens, and the second... The half-wave group, the first half-wave group, and the polarizing beam splitter are emitted from the second port of the multi-core pigtail. The light emitted from the second port of the multi-core pigtail passes sequentially through the polarizing beam splitter, the first half-wave group, the second half-wave group, the collimating lens, the second optical rotation unit, and the Wollaston prism to the reflecting mirror. After being reflected by the reflecting mirror, the light passes sequentially through the Wollaston prism, the second optical rotation unit, the collimating lens, the first half-wave group, and the polarizing beam splitter, and is emitted from the third port of the multi-core pigtail.

2. The same-side annulus according to claim 1, characterized in that, The front end face of the multi-core pigtail is coated with an anti-reflection film and ground to a preset tilt angle.

3. The same-side annulus according to claim 1, characterized in that, The first half-wave group includes two half-wave plates with an optical axis of 22.5°, which are arranged side by side and mirror symmetrically. The second half-wave group includes a half-wave plate with an optical axis of 45°, which is located at a preset position in the first half-wave group and does not fully cover it.

4. The same-side annulus according to claim 1, characterized in that, The collimating lens includes a spherical lens or a graduated refractive index lens.

5. The same-side annulus according to claim 1, characterized in that, The second optical rotation unit includes a Faraday optical rotation plate.

6. The same-side annulus according to claim 1, characterized in that, The Wollaston prism comprises two wedge-shaped plates with their optical axes perpendicular to each other.

7. The same-side annulus according to claim 1, characterized in that, The tilt angle of the reflector is determined based on the tilt angle of the first port and the tilt angle of the second port.

8. The same-side annulus according to claim 1, characterized in that, The deflection angle of the Wollaston prism is determined based on the tilt angle of the reflector, the tilt angle of the second port, and the tilt angle of the third port.

9. A method for preparing a ring on the same side, characterized in that, For preparing the same-side circulator as described in any one of claims 1-8, comprising: The polarizing beam splitter is fixed to the front end face of the multi-core pigtail. The first optical rotation unit is fixed on the surface of the polarizing beam splitter; The relative position between the multi-core pigtail and the collimating lens is fixed, with the front end face of the multi-core pigtail located at the rear focal point of the collimating lens; The second optical rotation unit and the Wollaston prism are attached and fixed inside the magnetic ring. The Wollaston prism is fixed through one side of the magnetic ring so that the optical axis of the Wollaston prism is aligned with the polarization state of the collimated beam. Adjust the tilt angle of the reflector to minimize insertion loss and fix the other side of the magnetic ring.

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