Low-cost miniaturized three-port two-stage isolation optical circulator

Abstract

The utility model relates to a low-cost miniaturized three-port two-stage isolation optical circulator, which comprises a first collimator, a circulator core and a second collimator which are sequentially arranged, and is characterized in that the circulator core comprises a first polarization splitting prism, a half-wave plate, a Faraday optical rotation crystal, a second polarization splitting prism and a rhombic prism; the right end face of the section of the first polarization splitting prism is attached to the left end face of the half-wave plate, the half-wave plate and the Faraday optical rotation crystal form an optical rotation combination, the left end face of the second polarization splitting prism is attached to the right end face of the Faraday optical rotation crystal, and the rhombic prism is located above the second polarization splitting prism. The first collimator is a double-fiber collimator, and the second collimator is a single-fiber collimator. The double-stage isolation optical circulator is reasonable in design, realizes a compact and small double-stage isolation optical circulator structure, not only can effectively improve the isolation degree of the optical circulator, but also can remarkably reduce the size and the cost of the optical circulator, and provides powerful support for further development of an optical fiber communication system.

Description

Technical Field

[0001] The utility model relates to a low-cost miniaturized three-port double-stage isolation optical circulator. Background Art

[0002] Optical circulators are important optical communication devices, widely used in fiber-optic communications, fiber-optic sensing, fiber-optic lasers, and other fields. They are multi-port, non-reciprocal devices that enable unidirectional transmission of optical signals. They are typically used to transmit an input optical signal from one port to the next sequential port without returning or transmitting to other ports. In fiber-optic communication systems, optical circulators are often combined with other devices such as fiber Bragg gratings (FBGs) and optical switches to achieve feature-rich optical signal processing and transmission. Traditional optical circulators mostly use magneto-optical materials, such as yttrium-doped iron garnet (YIG), to achieve unidirectional transmission of optical signals through the Faraday effect. However, with the advancement of optical communication technology, the performance requirements of fiber-optic systems continue to increase, such as low insertion loss, high isolation, wide bandwidth, miniaturization, and low cost. Traditional optical circulators are gradually unable to meet these increasingly stringent requirements.

[0003] In recent years, researchers have proposed the concept of a dual-stage isolation optical circulator to further improve the performance of optical circulators. By adding an additional optical isolator within the circulator, dual-stage isolation optical circulators significantly improve device isolation. This dual-stage isolation optical circulator effectively prevents reflected light from interfering with the signal source, ensuring signal integrity and transmission efficiency. It is suitable for high-speed, long-distance, and high-capacity fiber-optic communication network systems. However, existing dual-stage isolation optical circulators are typically complex, bulky, and expensive, which to some extent limits their application. Utility Model Content

[0004] The present invention aims to improve the problems existing in the above-mentioned prior art, that is, the technical problem to be solved by the present invention is to provide a low-cost miniaturized three-port two-stage isolated optical circulator.

[0005] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is: a low-cost miniaturized three-port two-stage isolated optical circulator, comprising a first collimator, a circulator core and a second collimator arranged in sequence, the circulator core comprising a first polarization beam splitter prism, a half-wave plate, a Faraday rotator crystal, a second polarization beam splitter prism, and a rhombus prism, the right end face of the cross section of the first polarization beam splitter prism is bonded to the left end face of the half-wave plate, the half-wave plate and the Faraday rotator crystal constitute an optical rotation combination, the left end face of the second polarization beam splitter prism is bonded to the Faraday rotator crystal, and the right end face of the cross section of the first polarization beam splitter prism is bonded to the left end face of the half-wave plate. The right end face of the crystal is bonded, and the rhombus prism is located above the second polarization splitter prism; the first collimator is a dual-fiber collimator and has a first port and a third port, and the second collimator is a single-fiber collimator and has a second port. The first collimator is used to collimate the output light of the first port into parallel light, and couple the collimated parallel light output from the second port through the circulator core to the third port for reception. The second collimator is used to receive the collimated parallel light output from the first port through the circulator core at the second port, and collimate the output light from the second port into parallel light.

[0006] Furthermore, the cross-sections of the first polarization splitter prism and the second polarization splitter prism are both trapezoidal structures, a first polarization splitter film is provided inside the first polarization splitter prism, and a second polarization splitter film is provided inside the second polarization splitter prism, and the first polarization splitter film and the second polarization splitter film are used to separate or synthesize P-polarized light and S-polarized light in the signal light.

[0007] Furthermore, the first polarization splitting film is parallel to the lower end face of the first polarization splitting prism; the second polarization splitting film is parallel to the upper end face of the second polarization splitting prism, and the lower end face and right end face of the second polarization splitting prism are both provided with high reflection films.

[0008] Furthermore, the cross-section of the rhombus prism is a parallelogram structure.

[0009] Furthermore, the collimated parallel light of the first port is directed horizontally downward at an angle A, and the collimated parallel light of the third port is directed horizontally upward at an angle A. The collimated parallel light of the first port and the third port form an angle 2A, and the light of the two ports is symmetrical about the axis of the first collimator in the horizontal direction.

[0010] Furthermore, the right end face of the second polarization beam splitter prism is parallel to the left end face of the second polarization beam splitter prism, and the angle between the lower end face and the right end face of the second polarization beam splitter prism is 90°-B. The angles A and B satisfy the following relationship: , where n1 is the refractive index of air and n2 is the refractive index of the second polarization beam splitter prism.

[0011] Furthermore, it also includes a glass outer sealing tube and a magnetic ring sleeved on the outside of the glass outer sealing tube. The first collimator and the second collimator are respectively arranged at two opposite ends of the glass outer sealing tube. A circulator core base is provided inside the glass outer sealing tube. The circulator core is installed in the circulator core base. The magnetic ring corresponds to the position of the circulator core.

[0012] Compared with the existing technology, the utility model has the following effects: the utility model has a reasonable design and realizes a compact and small dual-stage isolation optical circulator structure, which can not only effectively improve the isolation of the optical circulator, but also significantly reduce its size and cost, providing strong support for the further development of optical fiber communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the main structure of an embodiment of the utility model;

[0014] Figure 2 Schematic diagram of the angle of light emitted by the first collimator;

[0015] Figure 3 is a schematic diagram of the angle at which the first collimator rotates relative to the circulator core;

[0016] Figure 4 Schematic diagram of the structure of the circulator core;

[0017] Figure 5 Schematic diagram of light propagation from the input optical fiber to the right end face of the second polarization beam splitter prism;

[0018] Figure 6 Schematic diagram of light propagation from the right end face of the second polarization beam splitter prism to the common end optical fiber;

[0019] Figure 7 Schematic diagram of light propagation from the common end optical fiber to the lower end face of the second polarization beam splitter prism;

[0020] Figure 8 Schematic diagram of light propagation from the lower end face of the second polarization beam splitter prism to the receiving end optical fiber.

[0021] In the picture:

[0022] 101-first collimator; 102-circulator core base; 103-circulator core; 104-second collimator; 105-

[0023] Glass outer sealing tube; 106-magnetic ring; 301-first polarization beam splitter prism; 302-half-wave plate; 303-Faraday rotator crystal; 304-second polarization beam splitter prism; 305-rhombic prism; 3011-first polarization beam splitter film; 3012-second polarization beam splitter film; 3013-first high-reflection film; 3014-second high-reflection film; first port - Port 1; second port - Port 2; third port - Port 3.

[0024] The short bidirectional arrows indicate the P polarization state, and the dots indicate the S polarization state. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0026] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "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 the present invention, 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. Therefore, they should not be understood as limitations on the present invention.

[0027] like Figure 1 As shown, the present invention provides a low-cost, miniaturized, three-port, two-stage isolated optical circulator, comprising a first collimator 101, a circulator core 103, and a second collimator 104, which are sequentially arranged. The collimator 101 and the second collimator 104 are also included in the sequence. The collimator 101 and the second collimator 104 are respectively arranged at two opposite ends of the glass outer seal 105. A circulator core base 102 is provided within the glass outer seal 105. The circulator core 103 is mounted within the circulator core base 102. The magnetic ring 106 corresponds to the position of the circulator core 103.

[0028] In this embodiment, the glass outer sealing tube 105 is used to bond and fix the circulator core base 102, the first collimator 101, and the second collimator 104, thereby performing a mechanical fixing function. The circulator core base 102 is used to bond and fix the circulator core 103, thereby performing a mechanical fixing function. The magnetic ring 106 is used to provide a magnetic field so that the Faraday rotator crystal of the circulator core 103 can rotate the polarization direction of the input light under the magnetic field.

[0029] In this embodiment, the first collimator 101 is a dual-fiber collimator and has a first port Port1 and a third port Port3. The second collimator 104 is a single-fiber collimator and has a second port Port2. The first collimator 101 is used to collimate the output light of the first port into parallel light, and couple the collimated parallel light output from the second port Port2 through the circulator core 103 to the third port Port3 for reception. The second collimator 104 is used to receive the collimated parallel light output from the first port through the circulator core 103 at the second port Port2, and collimate the output light from the second port Port2 into parallel light. The circulator core 103 allows light to pass along a specified path.

[0030] In this embodiment, Figure 4 As shown, the circulator core 103 includes a first polarization beam splitter prism 301, a half-wave plate 302, a Faraday rotator crystal 303, a second polarization beam splitter prism 304, and an rhombus prism 305. The right end face of the cross section of the first polarization beam splitter prism 301 is bonded to the left end face of the half-wave plate 302, and the left end face of the Faraday rotator crystal 303 is bonded to the right end face of the half-wave plate 302. The half-wave plate 302 and the Faraday rotator crystal 303 form a polarization combination, which rotates the polarization direction by 90° when light propagates from left to right, and does not rotate the polarization direction when light propagates from right to left. The left end face of the second polarization beam splitter prism 304 is bonded to the right end face of the Faraday rotator crystal 303, and the rhombus prism 305 is located above the second polarization beam splitter prism 304. The refractive index n2 of the first polarization beam splitter prism 301 and the second polarization beam splitter prism is 1.5.

[0031] In this embodiment, Figure 4 As shown, the cross-sections of the first polarization beam splitter prism 301 and the second polarization beam splitter prism 304 are both trapezoidal structures, and the cross-section of the rhombus prism 305 is a parallelogram structure.

[0032] In this embodiment, Figure 4 As shown, the first polarization beam splitter prism 301 is internally provided with a first polarization beam splitter film 3011 that divides it into upper and lower portions. The first polarization beam splitter film 3011 is parallel to the lower end surface of the first polarization beam splitter prism 301. The second polarization beam splitter prism 304 is internally provided with a second polarization beam splitter film 3012 that divides it into upper and lower portions. The second polarization beam splitter film 3012 is parallel to the upper end surface of the second polarization beam splitter prism 304. The right end surface of the second polarization beam splitter prism 304 is provided with a first high-reflection film 3013, the lower end surface is provided with a second high-reflection film 3014, and the upper end surface of the second polarization beam splitter prism 304 is provided with a high-reflection film. The first polarization beam splitter film 3011 and the second polarization beam splitter film 3012 are used to separate or combine P-polarized light and S-polarized light in the signal light.

[0033] In this embodiment, the first port port1 and the third port port3 are both located on the left end surface of the first polarization beam splitting prism 301 , and the second port port2 is located on the right end surface of the rhombus prism 305 .

[0034] In this embodiment, Figure 2 As shown, the collimated parallel light from the first port port1 is directed horizontally downward at an angle A, and the collimated parallel light from the third port port3 is directed horizontally upward at an angle A. The collimated parallel light from the first port port1 and the third port port3 form an angle 2A, and the light from the two ports is symmetrical in the horizontal direction about the axis of the first collimator 101. Preferably, the angle A is 3°, that is, the collimated parallel light from the first port is directed horizontally downward at an angle A=3°, and the collimated parallel light from the third port is directed horizontally upward at an angle A=3°.

[0035] In this embodiment, Figure 3 As shown, the relative angle relationship between the first collimator 101 and the circulator core 103 is that the angular bisectors of the two outgoing light beams of the first collimator 101 rotate counterclockwise by an angle C=1.5° relative to the horizontal direction, so that the angle of the outgoing light from the first port port1 becomes 1.5 degrees downward from the horizontal, and the angle of the outgoing light from the third port port3 becomes 4.5 degrees upward from the horizontal.

[0036] In this embodiment, the right end face of the second polarization beam splitter prism 304 is parallel to the left end face of the second polarization beam splitter prism 304. The lower end face and the right end face of the second polarization beam splitter prism 304 form an angle of 90°-B. The angle B = 2°, so that the end faces of the first high-reflection film 3013 and the second high-reflection film 3014 form an angle of 88°.

[0037] In this embodiment, the angles A and B satisfy the following relationship: , where n1 is the refractive index of air and n2 is the refractive index of the second polarization beam splitter prism 304, so that the angle of the dual-fiber collimator matches the optical path of the circulator core.

[0038] In this embodiment, Figure 5 As shown, the angle bisectors of the two outgoing light beams from the first collimator 101 rotate counterclockwise relative to the incident plane of the first polarizing beam splitter prism 301, so that the angle bisectors of the two outgoing light beams from the first collimator 101 and the normal of the first polarizing beam splitter prism 301 form an angle C; the first port port1 is horizontally downwardly incident on the left end surface of the first polarizing beam splitter prism 301 at an angle AC, refracted, and then transmitted horizontally downwardly at an angle D to the first polarizing beam splitter film 3011;

[0039] The relationship between angles A, C, and D is as follows:

[0040] .

[0041] In this embodiment, the P-polarized light in the signal light is transmitted, while the S-polarized light is reflected. The S-polarized light is reflected by the lower end face of the first polarization beam splitter prism 301. After the P-polarized light and the S-polarized light respectively pass through the optical rotation combination composed of the half-wave plate 302 and the Faraday rotator crystal 303, the polarization directions of the two lights are changed, and the original P-polarized light becomes S-polarized light, and the original S-polarized light becomes P-polarized light. The rotated P-polarized light enters the second polarization beam splitter prism 304 and passes through the second polarization beam splitter film 3012. The rotated S-polarized light enters the second polarization beam splitter prism 304, is reflected by the upper end face of the second polarization beam splitter prism 304, and then by the second polarization beam splitter film. The P-polarized light and the S-polarized light are combined and transmitted to the right end face of the second polarization beam splitter prism 304 at a horizontal downward angle D.

[0042] In this embodiment, Figure 6 As shown, the signal light is reflected by the high-reflection film on the right end face of the second polarization beam splitter prism 304. The reflected light is transmitted horizontally downward to the second polarization beam splitter film 3012 at an angle D. The P-polarized light in the signal light is transmitted, and the S-polarized light is reflected. The S-polarized light is reflected by the upper end face of the second polarization beam splitter prism 304. After the P-polarized light and the S-polarized light pass through the Faraday rotator crystal 303 and the half-wave plate 302, respectively, the polarization directions of both remain unchanged. P-polarized light enters the first polarization splitter prism 301, is reflected by the lower end face of the first polarization splitter prism 301, and is then transmitted by the first polarization splitter film 3011. S-polarized light enters the first polarization splitter prism 301, is reflected by the first polarization splitter film 3011, and the two beams are combined and transmitted upward to the upper end face of the first polarization splitter prism 301, where they are reflected. They are then transmitted horizontally to the right at an angle D, where they are refracted. After refraction, they are transmitted horizontally upward at an angle E through the rhombus prism 305, where they are deflected and transmitted to the second signal port, port 2. Furthermore, the relationship between angles E and D is as follows:

[0043] .

[0044] In this embodiment, the second port Port2 is horizontally incident downwardly on the right end face of the first polarization splitting prism 301 at an angle E, causing refraction. After refraction, it is horizontally transmitted downwardly at an angle D to the upper end face of the first polarization splitting prism 301, where it is reflected and then transmitted to the first polarization splitting film 3011. The P-polarized light in the signal light is transmitted, while the S-polarized light is reflected. The P-polarized light is reflected by the lower end face of the first polarization splitting prism 301. After the P-polarized light and the S-polarized light pass through the half-wave plate 302 and the Faraday rotator crystal 303, respectively, their polarization directions change. The original P-polarized light becomes S-polarized light, and the original S-polarized light becomes P-polarized light. The rotated P light enters the second polarization splitter prism 304, is reflected by the upper end face of the second polarization splitter prism 304, and then passes through the second polarization splitter film 3012; the rotated S polarized light enters the second polarization splitter prism 304, is reflected by the second polarization splitter film 3012, and the P polarized light and the S polarized light are combined and transmitted to the lower end face of the second polarization splitter prism 304 at a vertical downward angle D.

[0045] In this embodiment, the signal light is reflected by the highly reflective coating on the lower end face of the second polarization beam splitter prism 304 at a reflection angle of BD. The reflected light is transmitted vertically upward to the second polarization beam splitter film 3012 at an angle of 2*BD. The P-polarized light in the signal light is transmitted, while the S-polarized light is reflected. The P-polarized light is reflected by the upper end face of the second polarization beam splitter prism 304. After passing through the Faraday rotator crystal 303 and the half-wave plate 302, respectively, the polarization directions of both the P-polarized light and the S-polarized light remain unchanged. The P-polarized light enters the first polarization beam splitter prism 301 and is transmitted by the first polarization beam splitter film 3011. The S-polarized light enters the first polarization beam splitter prism 301 and is reflected by the lower end face of the first polarization beam splitter prism 301 and then by the first polarization beam splitter film 3011. The two beams are combined and transmitted horizontally downward to the left end face of the first polarization beam splitter prism 301 at an angle of 2*BD. Based on the previously determined relationship between A, B, C, and D:

[0046] ;

[0047] ;

[0048] In the case of small angle incidence, the sine value is approximately equal to the angle value. It can be deduced that after 2*BD is refracted, the following refraction angle relationship is satisfied:

[0049] ;

[0050] That is, the outgoing light is transmitted horizontally downward at an angle of A+C to the third port.

[0051] In this embodiment, the range of angle A is 2 to 8 degrees, the range of angle B is 1 to 4 degrees, and the range of angle C is 0 to 4 degrees.

[0052] In this embodiment, the positions of the half-wave plate and the Faraday rotator crystal can be interchanged.

[0053] In this embodiment, all the bonding surfaces and signal port surfaces are provided with anti-reflection films.

[0054] In this embodiment, the angle 90°-B formed between the lower and right end faces of the second polarization beam splitter prism and the angle 2*A formed by the first collimator are key to achieving dual-stage isolation. The angle formed between the lower and right end faces of the second polarization beam splitter prism matches the light output cross angle of the fiber collimator, effectively separating the transmitted and reflected signals during optical signal transmission. This coordinated design of the polarization beam splitter's reflective surface and the dual-fiber angle not only avoids unnecessary signal reflections and losses, but also enhances the isolation of the optical circulator, achieving dual-stage isolation. It also makes the device's optical path layout more compact, reduces the number of required optical components, and facilitates device miniaturization, thereby reducing device complexity and manufacturing costs.

[0055] Specific implementation process:

[0056] (1) If Figure 5 As shown, light from the first port Port1 of the first collimator 101 is incident horizontally downward at an angle of AC=1.5° on the left end face of the first polarization beam splitter prism 301 and is refracted. After refraction, the light is transmitted horizontally downward at an angle of D=1° to the first polarization beam splitter film 3011. The P-polarized light in the signal light is transmitted, and the S-polarized light is reflected. The S-polarized light is reflected by the lower end face of the first polarization beam splitter prism 301. After the P-polarized light and the S-polarized light pass through the half-wave plate 302 and the Faraday rotator crystal 303 respectively, the polarization directions of the two lights change. The original P-polarized light becomes S-polarized light, and the original S-polarized light becomes P-polarized light. The rotated P-polarized light enters the second polarization splitting prism 304 and passes through the second polarization splitting film 3012. The rotated S-polarized light enters the second polarization splitting prism 304, is reflected by the upper end face of the second polarization prism 304, and then is reflected by the second polarization splitting film 3012. The P-polarized light and the S-polarized light are combined and transmitted to the right end face of the second polarization splitting prism 304, and the angle of incidence on the right end face of the second polarization splitting prism 304 is horizontally downward at D = 1°.

[0057] (2) If Figure 6As shown, after the signal light is reflected by the first high-reflection film 3013 on the right end face of the second polarization beam splitter prism 304, the reflected light is transmitted horizontally downward to the second polarization beam splitter film 3012 at an angle D = 1°. The P-polarized light in the signal light is transmitted, and the S-polarized light is reflected. The S-polarized light is reflected by the upper end face of the second polarization beam splitter prism 304. After the P-polarized light and the S-polarized light pass through the Faraday rotator crystal 303 and the half-wave plate 302 respectively, the polarization directions of both the P-polarized light and the S-polarized light remain unchanged. P-polarized light is incident on the first polarization splitter prism 301, reflected by the lower end face of the first polarization splitter prism, and then transmitted by the first polarization splitter film 3011. S-polarized light is incident on the first polarization splitter prism 301, reflected by the first polarization splitter film 3011, and the two are combined and transmitted horizontally upward at an angle D = 1° to the right end face of the first polarization splitter prism 301, where they are refracted. After refraction, they are transmitted horizontally upward at an angle E = 1.5° through the rhombus prism 305, and then the optical path is turned by the rhombus prism 305 to be transmitted to the second port Port2.

[0058] (3) If Figure 7 As shown, light from the second port Port2 of the second collimator 104 is deflected by the rhombic prism 305 and then horizontally downwardly incident on the right end face of the first polarization beam splitter prism 301 at an angle of E=1.5°, where it is refracted. After refraction, it is horizontally downwardly transmitted at an angle of D=1° and reflected by the upper end face of the first polarization beam splitter prism. Then, after passing through the first polarization beam splitting film 3011, the P-polarized light in the signal light is transmitted and the S-polarized light is reflected. The P-polarized light is reflected by the lower end face of the first polarization beam splitter prism 301. After the P-polarized light and the S-polarized light pass through the half-wave plate 302 and the Faraday rotator crystal 303, respectively, the polarization directions of the two are changed. The original P-polarized light becomes S-polarized light, and the original S-polarized light becomes P-polarized light. The rotated P-polarized light enters the second polarization beam splitter prism 304, is reflected by the upper end face of the second polarization beam splitter prism, and then passes through the second polarization beam splitter film 3012; the rotated S-polarized light enters the second polarization beam splitter prism 304, is reflected by the second polarization beam splitter film 3012, and the P-polarized light and the S-polarized light are combined and transmitted to the high-reflection film 3014 on the lower end face of the second polarization beam splitter prism 304. The incident angle BD = 1°

[0059] (4) If Figure 8As shown, the signal light is reflected by the second high-reflection film 3014 on the lower end surface of the second polarization beam splitter prism 304 and then transmitted upward. The reflection angle of the second high-reflection film 3014 is BD = 1°, and the angle between this angle and the vertical direction is 2B-D = 3°. The reflected light is transmitted upward to the second polarization beam splitter film 3012 at an angle of 2B-D. The P-polarized light in the signal light is transmitted, and the S-polarized light is reflected. The P-polarized light is reflected by the upper end surface of the second polarization beam splitter prism 304. After the P-polarized light and the S-polarized light pass through the Faraday rotator crystal 303 and the half-wave plate 302, respectively, the polarization directions of both the P-polarized light and the S-polarized light remain unchanged. The P-polarized light enters the first polarization splitting prism 301 and is transmitted by the first polarization splitting film 3011. The S-polarized light enters the first polarization splitting prism 301, is reflected by the lower end face of the first polarization splitting prism 301, and then is reflected by the first polarization splitting film 3011. The two beams are combined and transmitted horizontally downward at an angle of 2B-D=3° to the left end face of the first polarization splitting prism 301, refracted, and transmitted horizontally downward at an angle of 4.5° to the third port Port3 of the first collimator 101.

[0060] This optical circulator utilizes a unique optical path design. By rationally combining the light output cross angle of the dual-fiber collimator with the special optical path design within the optical circulator, a compact dual-stage isolation optical circulator structure is achieved. This design not only effectively improves the isolation of the optical circulator, but also significantly reduces its size and cost, providing strong support for the further development of fiber-optic communication systems.

[0061] If the present invention discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connection using bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by integral molding using a casting process) (except where it is obviously impossible to use an integrated molding process).

[0062] In addition, unless otherwise stated, the terms used in any technical solution disclosed in the above-mentioned utility model to express positional relationships or shapes include states or shapes that are approximate, similar or close thereto.

[0063] Any component provided by the present invention can be assembled from multiple separate components, or can be a separate component manufactured by an integral forming process.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and not to limit it; although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solution of the utility model, they should all be included in the scope of the technical solution for protection of the utility model.

Claims

1. A low-cost, miniaturized, three-port, dual-stage isolated optical circulator, characterized by: The optical fiber optical fiber optic cable comprises a first collimator, a circulator core, and a second collimator, which are arranged in sequence. The circulator core comprises a first polarization beam splitter prism, a half-wave plate, a Faraday rotator crystal, a second polarization beam splitter prism, and an rhombus prism. The right end face of the cross section of the first polarization beam splitter prism is bonded to the left end face of the half-wave plate. The half-wave plate and the Faraday rotator crystal form an optical rotation combination. The left end face of the second polarization beam splitter prism is bonded to the right end face of the Faraday rotator crystal. The rhombus prism is located above the second polarization beam splitter prism. The first collimator is a dual-fiber collimator having a first port and a third port. The second collimator is a single-fiber collimator having a second port. The first collimator is used to collimate the output light of the first port into parallel light and couple the collimated parallel light output from the second port through the circulator core to the third port for reception. The second collimator is used to receive the collimated parallel light output from the first port through the circulator core at the second port and collimate the output light of the second port into parallel light.

2. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 1, characterized in that: The cross-sections of the first polarization beam splitter prism and the second polarization beam splitter prism are both trapezoidal structures. A first polarization beam splitter film is provided inside the first polarization beam splitter prism, and a second polarization beam splitter film is provided inside the second polarization beam splitter prism. The first polarization beam splitter film and the second polarization beam splitter film are used to separate or synthesize P-polarized light and S-polarized light in the signal light.

3. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 2, characterized in that: The first polarization beam splitting film is parallel to the lower end face of the first polarization beam splitting prism; the second polarization beam splitting film is parallel to the upper end face of the second polarization beam splitting prism, and the lower end face and right end face of the second polarization beam splitting prism are both provided with high reflection films.

4. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 2, characterized in that: The cross section of the rhombus prism is a parallelogram structure.

5. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 1, characterized in that: The collimated parallel light of the first port is directed horizontally downward at an angle A, and the collimated parallel light of the third port is directed horizontally upward at an angle A. The collimated parallel light of the first port and the third port form an angle 2A, and the light of the two ports is symmetrical about the axis of the first collimator in the horizontal direction.

6. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 5, characterized in that: The right end face of the second polarization beam splitter prism is parallel to the left end face of the second polarization beam splitter prism. The lower end face and the right end face of the second polarization beam splitter prism form an angle of 90°-B. The angles A and B satisfy the following relationship: , where n1 is the refractive index of air and n2 is the refractive index of the second polarization beam splitter prism.

7. The low-cost, miniaturized three-port, dual-stage isolated optical circulator according to claim 1, characterized in that: The invention also includes a glass outer sealing tube and a magnetic ring sleeved on the outside of the glass outer sealing tube. The first collimator and the second collimator are respectively arranged at two opposite ends of the glass outer sealing tube. A circulator core base is arranged inside the glass outer sealing tube. The circulator core is installed in the circulator core base. The magnetic ring corresponds to the position of the circulator core.

Images