A high isolation optical splitter

Abstract

The present invention provides a high-isolation optical splitter for use in the field of optical communications. The high-isolation optical splitter includes an input optical fiber, a first output optical fiber, an input light splitting / combining device, a first output light splitting / combining device, an input optical rotation device, a first output optical rotation device, a first lens, an isolator core, a second lens, a second output optical rotation device, a second output light splitting / combining device, and a second output optical fiber. By adopting an integrated structural design, the high-isolation optical splitter realizes the functional integration of an optical isolator and a light splitter, which can not only realize the input of an optical signal from an input optical fiber and the distribution to two output optical fibers for output, but also realize reverse optical isolation, thereby reducing the damage to the input-end light source. In system applications, a single high-isolation optical splitter is used to replace two traditional independent optical isolators and optical splitters, which can effectively reduce the assembly space, reduce the difficulty of assembly, simplify the assembly process, and is conducive to the development of system miniaturization and integrated applications.

Description

[0001] The invention relates to the field of optical fiber communication, and in particular to a high-isolation optical splitter used in an optical amplifier system. Background Art

[0002] In fiber-optic communication systems, optical isolators, due to their unidirectional transmission performance, can effectively reduce the interference of reverse light on the transmission line to the laser, alleviate the deterioration of system transmission performance, reduce the probability of optical amplifier gain changes and self-excitation, maintain the working stability of the laser, and extend the service life of the laser. They are an important passive optical device widely used in fiber-optic communication systems. Optical splitters are another type of passive optical device that can distribute optical signals from one link to multiple links, and are also widely used in fiber-optic communication systems. In particular, in optical amplifier systems, optical isolators and optical splitters are often used in combination for reverse light isolation and power splitting after signal amplification.

[0003] The optical isolator and splitter traditionally used in optical amplification systems are two independent devices, which require a large assembly space, have high assembly costs, and have certain assembly risks.

[0004] In view of the prior art, the purpose of the present invention is to provide a high-isolation optical splitter that integrates the functions of a traditional optical isolator and an optical splitter into one device.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A high-isolation optical splitter comprises an input optical fiber, a first output optical fiber, an input light splitting / combining device, a first output light splitting / combining device, an input optical rotation device, a first output optical rotation device, a first lens, an isolator core, a second lens, a second output optical rotation device, a second output light splitting / combining device, and a second output optical fiber, which are arranged in sequence;

[0007] The input light splitting / combining device and the input optical rotation device correspond to the input optical fiber and are sequentially arranged between the end face of the input optical fiber close to the first lens and the first lens; the first output light splitting / combining device and the first output optical rotation device correspond to the first output optical fiber and are sequentially arranged between the end face of the first output optical fiber close to the first lens and the first lens; the second output light splitting / combining device and the second output optical rotation device correspond to the second output optical fiber and are sequentially arranged between the end face of the second output optical fiber close to the second lens and the second lens;

[0008] In addition, the isolator core comprises a first Faraday rotator, a beam splitter, a second Faraday rotator and a magnetic ring in which the first Faraday rotator, the beam splitter and the second Faraday rotator are arranged in sequence, and the openings at both ends of the magnetic ring are respectively opposite to the first lens and the second lens;

[0009] When the incident light beam is input from the input optical fiber, it is split after passing through the beam splitter in the isolator core, and the reflected light is output from the first output optical fiber, and the transmitted light is output from the second output optical fiber; when the incident light beam is input from the first output optical fiber, the light beams on the input optical fiber and the second output optical fiber are isolated; when the incident light beam is input from the second output optical fiber, the light beams on the input optical fiber and the first output optical fiber are isolated.

[0010] As a possible implementation, further, the first output optical fiber is combined with the input optical fiber to form a dual-fiber optical fiber head structure, and the first output optical fiber and the input optical fiber are symmetrical along the virtual central axis of the dual-fiber optical fiber head; the second output optical fiber and the first output optical fiber are both located on the same side of the virtual central axis.

[0011] Preferably, the second output optical fiber is one of the optical fibers of a dual-fiber optical fiber head, and the dual-fiber optical fiber head has the same hole spacing as the dual-fiber optical fiber head formed by the first output optical fiber and the input optical fiber.

[0012] Furthermore, the input light splitting / combining device and the input optical rotation device correspond to the input optical fiber and are sequentially arranged on the end face of the input optical fiber close to the first lens; the first output light splitting / combining device and the first output optical rotation device correspond to the first output optical fiber and are sequentially arranged on the end face of the first output optical fiber close to the first lens; the second output light splitting / combining device and the second output optical rotation device correspond to the second output optical fiber and are sequentially arranged on the end face of the second output optical fiber close to the second lens; in short, the input light splitting / combining device is fixed on the input optical fiber, and the input optical rotation device is fixed on the input light splitting / combining device; the first output light splitting / combining device is fixed on the first output optical fiber, and the first output optical rotation device is fixed on the first output light splitting / combining device; the second output light splitting / combining device is fixed on the second output optical fiber, and the second output optical rotation device is fixed on the second output light splitting / combining device.

[0013] Optionally, the input light splitting / combining device has the same size as the first output light splitting / combining device and the second output light splitting / combining device.

[0014] Furthermore, the light splitting / combining device is a displacement-type birefringent crystal, which is used to realize the light splitting / combining of o-light and e-light in the crystal; the optical axis of the birefringent crystal is oblique to the crystal surface at an angle of 45 degrees; the separation direction of o-light and e-light is perpendicular to the propagation direction of the light beam and parallel to the relative displacement direction of the input optical fiber and the output optical fiber.

[0015] Further, when the input light splitting / combining device is parallel to the optical axis direction of the first output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotator, the first output optical rotator, and the first Faraday rotator is 90 degrees; when the input light splitting / combining device is perpendicular to the optical axis direction of the first output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotator, the first output optical rotator, and the first Faraday rotator is 0 degree; when the input light splitting / combining device is parallel to the optical axis direction of the second output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotator, the second output optical rotator, and the second Faraday rotator is 0 degree; when the input light splitting / combining device is parallel to the optical axis direction of the second output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotator, the second output optical rotator, and the second Faraday rotator is 90 degrees.

[0016] Furthermore, the optical rotation device is a 1 / 2λ phase-delay quartz wave plate crystal, which is used to rotate the polarization direction of linearly polarized light; the combination of the input optical rotation device and the first output optical rotation device realizes an optical rotation angle of 45 degrees, and the combination of the input optical rotation device and the second output optical rotation device also realizes an optical rotation angle of 45 degrees.

[0017] Optionally, the input optical rotation device, the first output optical rotation device, and the second output optical rotation device have the same size.

[0018] Furthermore, the first lens and the second lens are a C lens or other lens forms with double-sided focal planes, which are used for focusing and collimating the light beam; the input optical fiber and the first output optical fiber are located at one focal plane of the first lens, and the splitting surface of the beam splitter is located at another focal plane of the first lens; the second output optical fiber is located at one focal plane of the second lens, and the splitting surface of the beam splitter is located at another focal plane of the second lens.

[0019] Optionally, the collimated light spots of the first lens and the second lens are consistent.

[0020] Optionally, the first lens and the second lens are of the same size and material.

[0021] Furthermore, the first Faraday rotator and the second Faraday rotator are magneto-optical crystals, and the rotation angle of the polarization direction of the linearly polarized light is 22.5 degrees.

[0022] Optionally, the first Faraday rotator and the second Faraday rotator are of the same size.

[0023] Furthermore, the magnetic ring is a permanent magnet used to provide the saturation magnetic field strength of the magneto-optical crystal, so that the magneto-optical crystal can achieve fixed rotation of the polarization direction of linearly polarized light; the direction of the magnetic field is parallel to the direction of light propagation.

[0024] Optionally, when linear polarized light is incident from the N-level magnetic field, the polarization direction rotates clockwise; when linear polarized light is incident from the S-level magnetic field, the polarization direction rotates counterclockwise.

[0025] Furthermore, the beam splitter is a glass flat plate with a certain thickness, and the beam splitting surface is coated with a beam splitting power TAP film or a beam splitting wavelength WDM film.

[0026] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: the present invention unifies the functions of the optical isolator and the spectrometer in one device through the adoption of an integrated structural design, thereby reducing the assembly space, lowering the assembly difficulty, simplifying the assembly process, and facilitating the development of system miniaturization and integrated applications.

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0028] Figure 1 It is a three-dimensional schematic diagram of the overall structure of embodiments 1 and 2 of the high isolation spectrometer of the present invention;

[0029] Figure 2 It is a three-dimensional schematic diagram of the isolator core of the high isolation spectrometer embodiments 1 and 2 of the present invention;

[0030] Figure 3 The front view and right view of the assembly structure of the reflective end of the high isolation spectrometer embodiment 1 of the present invention;

[0031] Figure 4 The front view and the left view are the assembly structure of the transmission end of the high isolation spectrometer embodiment 1 of the present invention;

[0032] Figure 5 Schematic diagram of the forward optical path of the high isolation spectrometer embodiment 1 of the present invention;

[0033] Figure 6 Schematic diagram of the reverse optical path of the high isolation spectrometer embodiment 1 of the present invention;

[0034] Figure 7 The front view and right view of the assembly structure of the reflective end of the high isolation spectrometer embodiment 2 of the present invention;

[0035] Figure 8 The front view and the left view are the assembly structure of the transmission end of the high isolation spectrometer embodiment 2 of the present invention;

[0036] Fig. 9 Schematic diagram of the forward optical path of the high isolation spectrometer embodiment 2 of the present invention;

[0037] Fig.10 Schematic diagram of the reverse optical path of embodiment 2 of the high isolation spectrometer of the present invention. DETAILED DESCRIPTION Example 1

[0038] like Figure 1 , Figure 2 As shown, the structure of this embodiment includes an input optical fiber 1, a first output optical fiber 2, an input light splitting / combining device 3, a first output light splitting / combining device 4, an input optical rotation device 5, a first output optical rotation device 6, a first lens 7, an isolator core 8, a second lens 9, a second output optical rotation device 10, a second output light splitting / combining device 11, and a second output optical fiber 12; the isolator core 8 includes a first Faraday rotator 801, a beam splitter 802, a second Faraday rotator 803, and a magnetic ring 804 arranged in sequence; when an incident light beam is input from the input optical fiber 1, it is split by the beam splitter 802 in the isolator core 8, and the reflected light is output from the first output optical fiber 2, and the transmitted light is output from the second output optical fiber 12; when an incident light beam is input from the first output optical fiber 2, the light beams on the input optical fiber 1 and the second output optical fiber 12 are isolated; when an incident light beam is input from the second output optical fiber 12, the light beams on the input optical fiber 1 and the first output optical fiber 2 are isolated.

[0039] like Figure 1 As shown, the first output optical fiber 2 and the input optical fiber 1 are combined into a dual-fiber optical fiber head, which are located on the same side of the device, and the second output optical fiber 12 is located on the other side of the device; the first output optical fiber 2 and the input optical fiber 1 are symmetrical about the central axis of the dual-fiber optical fiber head; the second output optical fiber 12 and the input optical fiber 1 are located on both sides of the central axis of the device, and are located on the same side of the central axis of the device as the first output optical fiber 2.

[0040] like Figure 3 , Figure 4As shown, the input light splitting / combining device 3 is fixed on the input optical fiber 1, and the input optical rotation device 5 is fixed on the input light splitting / combining device 3; the first output light splitting / combining device 4 is fixed on the first output optical fiber 2, and the first output optical rotation device 6 is fixed on the first output light splitting / combining device 4; the second output light splitting / combining device 11 is fixed on the second output optical fiber 12, and the second output optical rotation device 10 is fixed on the second output light splitting / combining device 11. The light splitting / combining devices 3, 4, and 11 are displacement-type birefringent crystals, which are used to realize the light splitting / combining of o-light and e-light in the crystal, and their corresponding optical axes 301, 401, and 1101 are obliquely intersected with the crystal surface at an angle of 45 degrees. The separation direction of o-light and e-light is perpendicular to the propagation direction of the light beam and parallel to the relative displacement direction of the input optical fiber and the output optical fiber. The optical rotation devices 5, 6, and 11 are 1 / 2λ phase-delay quartz wave plate crystals, which are used to rotate the polarization direction of linearly polarized light. The optical axis 501 of the input optical rotation device 5 is parallel to the crystal surface, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 0 degree; the optical axis 601 of the first output optical rotation device 6 is oblique to the crystal surface, and the angle with the x-axis is 22.5 degrees, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 45 degrees; the optical axis 1001 of the second output optical rotation device 10 is oblique to the crystal surface, and the angle with the x-axis is 22.5 degrees, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 45 degrees.

[0041] like Figure 1 , Figure 5 As shown, the first lens 7 and the second lens 9 are C lenses used for focusing and collimating the light beam; the beam splitter 802 is a glass flat plate with a certain thickness, and the beam splitting surface 8021 is coated with a beam splitting power TAP film to achieve reflection and transmission of the incident light beam in a certain proportion. The input optical fiber 1 and the first output optical fiber 2 are located at one focal plane of the first lens 7, and the beam splitting surface 8021 of the beam splitter 802 is located at another focal plane of the first lens; the second output optical fiber 12 is located at one focal plane of the second lens 9, and the beam splitting surface 8021 of the beam splitter 802 is located at another focal plane of the second lens.

[0042] like Figure 2 , Figure 5 As shown, the first Faraday rotator 801 and the second Faraday rotator 803 are magneto-optical crystals, and the rotation angle of the polarization direction of the linear polarized light is 22.5 degrees. The magnetic ring 804 is a permanent magnet, which is used to provide the saturation magnetic field strength of the magneto-optical crystal, so that the magneto-optical crystal can achieve fixed rotation of the polarization direction of the linear polarized light; the direction of the magnetic field is parallel to the direction of light propagation. When the linear polarized light is incident from the N-level magnetic field, the polarization direction rotates clockwise; when the linear polarized light is incident from the S-level magnetic field, the polarization direction rotates counterclockwise.

[0043] like Figure 5As shown, the forward optical path realized by the device is as follows: the incident light beam is input from the input optical fiber 1 along the z-axis direction, and generates separation of two linearly polarized light beams o and e in the x direction through the input light splitting / combining device 3, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linearly polarized light beams in the x and y directions pass through the input optical rotation device 5 without generating optical rotation; enter the first lens 7, and are incident on the first Faraday rotator 801 from the Nth level, and the polarization directions of the two linearly polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected and part of the light is transmitted; the reflected light is reflected back to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to be incident on the first output optical rotation device 6, and rotated 45 clockwise degrees, so far, the total optical rotation angle of the linear polarized light is 90 degrees. Since the optical axes of the first output splitter / combiner 4 and the input splitter / combiner 3 are parallel to each other, the two beams of linear polarized light enter the first output splitter / combiner 4 to generate combined light, and finally reach the first output optical fiber 2 for output; the transmitted light is transmitted to the second Faraday rotator 803, and the polarization direction rotates 22.5 degrees clockwise, passes through the second lens 9 and enters the second output optical rotation device 10, and rotates 45 degrees clockwise. So far, the total optical rotation angle of the linear polarized light is 90 degrees. Since the optical axes of the second output splitter / combiner 11 and the input splitter / combiner 3 are perpendicular to each other, the two beams of linear polarized light enter the second output splitter / combiner 11 to generate combined light, and finally reach the second output optical fiber 12 for output.

[0044] like Figure 6 As shown, the reverse optical path realized by the device is: the incident light beam is input from the first output optical fiber 2 along the z-axis direction, and passes through the first output light splitting / combining device 4 to generate the separation of two linear polarized light beams o and e in the x direction, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linear polarized light beams in the x and y directions pass through the first output optical rotation device 6 to generate optical rotation, and the polarization directions of the two linear polarized light beams are respectively rotated 45 degrees counterclockwise; enter the first lens 7, and are incident on the first Faraday rotator 801 from the Nth level, and the polarization directions of the two linear polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected , part of the light is transmitted; the reflected light is reflected back to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to enter the input optical rotation device 5 without generating optical rotation. At this point, the total optical rotation angle of the linearly polarized light is 0 degree. Since the optical axis directions of the first output light splitting / combining device 4 and the input light splitting / combining device 3 are parallel to each other, the two beams of linearly polarized light enter the input light splitting / combining device 3 without generating combined light, and the input optical fiber 1 has no light output; the transmitted light passes through the second Faraday rotator 803 and the second lens 9 in sequence, and the emission direction deviates from the second output optical fiber 12, that is, the second output optical fiber 12 has no light output.

[0045] The incident light beam is input from the second output optical fiber 12 along the z-axis direction, and passes through the second output light splitting / combining device 11 to generate separation of two linearly polarized light beams o and e in the x direction, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linearly polarized light beams in the x and y directions pass through the second output optical rotation device 10 to generate optical rotation, and the polarization directions of the two linearly polarized light beams are respectively rotated 45 degrees counterclockwise; enter the second lens 9, and are incident on the second Faraday rotator 803 from the Nth level, and the polarization directions of the two linearly polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected and part of the light is generated Transmission: The transmitted light is transmitted to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to enter the input optical rotation device 5 without generating optical rotation. At this point, the total optical rotation angle of the linearly polarized light is 0 degrees. Since the optical axis directions of the second output light splitting / combining device 11 and the input light splitting / combining device 3 are perpendicular to each other, the two beams of linearly polarized light enter the input light splitting / combining device 3 without generating combined light, and the input optical fiber 1 has no light output; the reflected light passes through the second Faraday rotator 803 and the second lens 9 in sequence, and the emission direction deviates from the first output optical fiber 2, that is, the first output optical fiber 2 has no light output. Example 2

[0046] like Figure 1 , Figure 2 As shown, the structure of this embodiment includes an input optical fiber 1, a first output optical fiber 2, an input light splitting / combining device 3, a first output light splitting / combining device 4, an input optical rotation device 5, a first output optical rotation device 6, a first lens 7, an isolator core 8, a second lens 9, a second output optical rotation device 10, a second output light splitting / combining device 11, and a second output optical fiber 12; the isolator core 8 includes a first Faraday rotator 801, a beam splitter 802, a second Faraday rotator 803, and a magnetic ring 804 arranged in sequence; when an incident light beam is input from the input optical fiber 1, it is split by the beam splitter 802 in the isolator core 8, and the reflected light is output from the first output optical fiber 2, and the transmitted light is output from the second output optical fiber 12; when an incident light beam is input from the first output optical fiber 2, the light beams on the input optical fiber 1 and the second output optical fiber 12 are isolated; when an incident light beam is input from the second output optical fiber 12, the light beams on the input optical fiber 1 and the first output optical fiber 2 are isolated.

[0047] like Figure 1 As shown, the first output optical fiber 2 and the input optical fiber 1 are combined into a dual-fiber optical fiber head, which are located on the same side of the device, and the second output optical fiber 12 is located on the other side of the device; the first output optical fiber 2 and the input optical fiber 1 are symmetrical about the central axis of the dual-fiber optical fiber head; the second output optical fiber 12 and the input optical fiber 1 are located on both sides of the central axis of the device, and are located on the same side of the central axis of the device as the first output optical fiber 2.

[0048] like Figure 7 , Figure 8 As shown, the input light splitting / combining device 3 is fixed on the input optical fiber 1, and the input optical rotation device 5 is fixed on the input light splitting / combining device 3; the first output light splitting / combining device 4 is fixed on the first output optical fiber 2, and the first output optical rotation device 6 is fixed on the first output light splitting / combining device 4; the second output light splitting / combining device 11 is fixed on the second output optical fiber 12, and the second output optical rotation device 10 is fixed on the second output light splitting / combining device 11. The light splitting / combining devices 3, 4, and 11 are displacement-type birefringent crystals, which are used to realize the light splitting / combining of o-light and e-light in the crystal, and their corresponding optical axes 301, 401, and 1101 are obliquely intersected with the crystal surface at an angle of 45 degrees. The separation direction of o-light and e-light is perpendicular to the propagation direction of the light beam and parallel to the relative displacement direction of the input optical fiber and the output optical fiber. The optical rotation devices 5, 6, and 11 are 1 / 2λ phase-delay quartz wave plate crystals, which are used to rotate the polarization direction of linearly polarized light. The optical axis 501 of the input optical rotation device 5 is parallel to the crystal surface, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 0 degree; the optical axis 601 of the first output optical rotation device 6 is oblique to the crystal surface, and the angle with the x-axis is 22.5 degrees, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 45 degrees; the optical axis 1001 of the second output optical rotation device 10 is oblique to the crystal surface, and the angle with the x-axis is 22.5 degrees, and the rotation angle of the x-axis, y-axis and 45-degree polarization direction is 45 degrees.

[0049] like Figure 1 , Figure 5 As shown, the first lens 7 and the second lens 9 are C lenses used for focusing and collimating the light beam; the beam splitter 802 is a glass flat plate with a certain thickness, and the beam splitting surface 8021 is coated with a beam splitting power TAP film to achieve reflection and transmission of the incident light beam in a certain proportion. The input optical fiber 1 and the first output optical fiber 2 are located at one focal plane of the first lens 7, and the beam splitting surface 8021 of the beam splitter 802 is located at another focal plane of the first lens; the second output optical fiber 12 is located at one focal plane of the second lens 9, and the beam splitting surface 8021 of the beam splitter 802 is located at another focal plane of the second lens.

[0050] like Figure 2 , Fig. 9 As shown, the first Faraday rotator 801 and the second Faraday rotator 803 are magneto-optical crystals, and the rotation angle of the polarization direction of the linear polarized light is 22.5 degrees. The magnetic ring 804 is a permanent magnet, which is used to provide the saturation magnetic field strength of the magneto-optical crystal, so that the magneto-optical crystal can achieve fixed rotation of the polarization direction of the linear polarized light; the direction of the magnetic field is parallel to the direction of light propagation. When the linear polarized light is incident from the N-level magnetic field, the polarization direction rotates clockwise; when the linear polarized light is incident from the S-level magnetic field, the polarization direction rotates counterclockwise.

[0051] like Fig. 9As shown, the forward optical path realized by the device is as follows: the incident light beam is input from the input optical fiber 1 along the z-axis direction, and generates separation of two linearly polarized light beams o and e in the x direction through the input light splitting / combining device 3, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linearly polarized light beams in the x and y directions pass through the input optical rotation device 5 without generating optical rotation; enter the first lens 7, and are incident on the first Faraday rotator 801 from the Nth level, and the polarization directions of the two linearly polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected and part of the light is transmitted; the reflected light is reflected back to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to be incident on the first output optical rotation device 6, and rotated 4 degrees clockwise 5 degrees. At this point, the total optical rotation angle of the linear polarized light is 90 degrees. Since the optical axes of the first output light splitting / combining device 4 and the input light splitting / combining device 3 are parallel to each other, the two beams of linear polarized light enter the first output light splitting / combining device 4 to generate combined light, and finally reach the first output optical fiber 2 for output; the transmitted light is transmitted to the second Faraday rotator 803, and the polarization direction rotates 22.5 degrees clockwise, passes through the second lens 9 and enters the second output optical rotation device 10, and rotates 45 degrees counterclockwise. At this point, the total optical rotation angle of the linear polarized light is 0 degree. Since the optical axes of the second output light splitting / combining device 11 and the input light splitting / combining device 3 are parallel to each other, the two beams of linear polarized light enter the second output light splitting / combining device 11 to generate combined light, and finally reach the second output optical fiber 12 for output.

[0052] like Fig.10 As shown, the reverse optical path realized by the device is: the incident light beam is input from the first output optical fiber 2 along the z-axis direction, and passes through the first output light splitting / combining device 4 to generate the separation of two linear polarized light beams o and e in the x direction, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linear polarized light beams in the x and y directions pass through the first output optical rotation device 6 to generate optical rotation, and the polarization directions of the two linear polarized light beams are respectively rotated 45 degrees counterclockwise; enter the first lens 7, and are incident on the first Faraday rotator 801 from the Nth level, and the polarization directions of the two linear polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected , part of the light is transmitted; the reflected light is reflected back to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to enter the input optical rotation device 5 without generating optical rotation. At this point, the total optical rotation angle of the linearly polarized light is 0 degree. Since the optical axis directions of the first output light splitting / combining device 4 and the input light splitting / combining device 3 are parallel to each other, the two beams of linearly polarized light enter the input light splitting / combining device 3 without generating combined light, and the input optical fiber 1 has no light output; the transmitted light passes through the second Faraday rotator 803 and the second lens 9 in sequence, and the emission direction deviates from the second output optical fiber 12, that is, the second output optical fiber 12 has no light output.

[0053] The incident light beam is input from the second output optical fiber 12 along the z-axis direction, and passes through the second output light splitting / combining device 11 to generate separation of two linear polarized light beams o and e in the x direction, and the polarization directions of the o and e lights are respectively in the x and y directions; the two linear polarized light beams in the x and y directions pass through the second output optical rotation device 10 to generate optical rotation, and the polarization directions of the two linear polarized light beams are respectively rotated 45 degrees clockwise; enter the second lens 9, and are incident on the second Faraday rotator 803 from the Nth level, and the polarization directions of the two linear polarized light beams are respectively rotated 22.5 degrees clockwise, and are focused on the splitting surface 8021 of the beam splitter 802, and part of the light is reflected and part of the light is generated Transmission: The transmitted light is transmitted to the first Faraday rotator 801, and the polarization direction is rotated 22.5 degrees clockwise again, and then passes through the first lens 7 to enter the input optical rotation device 5 without generating optical rotation. At this point, the total optical rotation angle of the linearly polarized light is 90 degrees. Since the optical axis directions of the second output light splitting / combining device 11 and the input light splitting / combining device 3 are parallel to each other, the two linearly polarized lights enter the input light splitting / combining device 3 without generating combined light, and the input optical fiber 1 has no light output; the reflected light passes through the second Faraday rotator 803 and the second lens 9 in sequence, and the emission direction deviates from the first output optical fiber 2, that is, the first output optical fiber 2 has no light output.

[0054] It should be noted that the embodiments disclosed herein are subject to modification and change, and replacement and equivalent components of the embodiments are well known to those skilled in the art. It should be clear to those skilled in the art that various changes made to the present invention in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims are within the scope of protection of the present invention.

Claims

1. A high isolation optical splitter, characterized in that: The optical fiber comprises an input optical fiber, a first output optical fiber, an input light splitting / combining device, a first output light splitting / combining device, an input optical rotation device, a first output optical rotation device, a first lens, an isolator core, a second lens, a second output optical rotation device, a second output light splitting / combining device, and a second output optical fiber, which are arranged in sequence; wherein the input light splitting / combining device and the input optical rotation device correspond to the input optical fiber and are arranged in sequence between the end face of the input optical fiber close to the first lens and the first lens; the first output light splitting / combining device and the first output optical rotation device correspond to the first output optical fiber. The optical fiber corresponds to and is sequentially arranged between the end face of the first output optical fiber close to the first lens and the first lens; the second output light splitting / combining device and the second output light rotation device correspond to the second output optical fiber and are sequentially arranged between the end face of the second output optical fiber close to the second lens and the second lens; in addition, the isolator core includes a first Faraday rotator, a beam splitter, a second Faraday rotator, and a magnetic ring in which the first Faraday rotator, the beam splitter, and the second Faraday rotator are arranged in sequence, and the open ends of the magnetic ring are respectively opposite to the first lens and the second lens; When the incident light beam is input from the input optical fiber, it is split by the beam splitter in the isolator core, the reflected light is output from the first output optical fiber, and the transmitted light is output from the second output optical fiber; when the incident light beam is input from the first output optical fiber, the light beams on the input optical fiber and the second output optical fiber are isolated; when the incident light beam is input from the second output optical fiber, the light beams on the input optical fiber and the first output optical fiber are isolated; The first output optical fiber and the input optical fiber are combined to form a dual-fiber optical fiber head structure, and the first output optical fiber and the input optical fiber are symmetrical along the virtual central axis of the dual-fiber optical fiber head; the second output optical fiber and the first output optical fiber are both located on the same side of the virtual central axis; The input light splitting / combining device and the input optical rotation device correspond to the input optical fiber and are sequentially arranged on the end face of the input optical fiber close to the first lens; the first output light splitting / combining device and the first output optical rotation device correspond to the first output optical fiber and are sequentially arranged on the end face of the first output optical fiber close to the first lens; the second output light splitting / combining device and the second output optical rotation device correspond to the second output optical fiber and are sequentially arranged on the end face of the second output optical fiber close to the second lens.

2. The high isolation optical splitter according to claim 1, characterized in that: The second output optical fiber is one of the optical fibers of a dual-fiber optical fiber head, and the dual-fiber optical fiber head has the same hole spacing as the dual-fiber optical fiber head formed by the first output optical fiber and the input optical fiber.

3. The high isolation optical splitter according to claim 1, characterized in that: The light splitting / combining device is a displacement-type birefringent crystal, which is used to realize the light splitting / combining of o-light and e-light in the crystal; the optical axis of the birefringent crystal is obliquely intersected with the crystal surface at an angle of 45 degrees; the separation direction of o-light and e-light is perpendicular to the propagation direction of the light beam and parallel to the relative displacement direction of the input optical fiber and the output optical fiber.

4. The high isolation optical splitter according to claim 1, characterized in that: When the input light splitting / combining device is parallel to the optical axis direction of the first output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotation device, the first output optical rotation device, and the first Faraday rotator is 90 degrees; when the input light splitting / combining device is perpendicular to the optical axis direction of the first output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotation device, the first output optical rotation device, and the first Faraday rotator is 0 degree; when the input light splitting / combining device is parallel to the optical axis direction of the second output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotation device, the second output optical rotation device, and the second Faraday rotator is 0 degree; when the input light splitting / combining device is parallel to the optical axis direction of the second output light splitting / combining device, the optical rotation angle achieved by the combination of the input optical rotation device, the second output optical rotation device, and the second Faraday rotator is 90 degrees.

5. The high isolation optical splitter according to claim 1, characterized in that: The input optical rotator, the first output optical rotator and the second output optical rotator are all 1 / 2λ phase-delay quartz wave plate crystals, used to rotate the polarization direction of linearly polarized light; the input optical rotator and the first output optical rotator are combined to achieve an optical rotation angle of 45 degrees, and the input optical rotator and the second output optical rotator are combined to achieve an optical rotation angle of 45 degrees; the input optical rotator, the first output optical rotator and the second output optical rotator are consistent in size.

6. The high isolation optical splitter according to claim 1, characterized in that: The first lens and the second lens are C lenses or double-sided focal plane lenses, which are used for focusing and collimating light beams; the input optical fiber and the first output optical fiber are located at one focal plane of the first lens, and the beam splitting surface of the beam splitter is located at another focal plane of the first lens; The second output optical fiber is located at a focal plane of the second lens, and the beam splitting surface of the beam splitter is located at another focal plane of the second lens; the collimated light spots of the first lens and the second lens are consistent.

7. The high isolation optical splitter according to claim 1, characterized in that: The first Faraday rotator and the second Faraday rotator are a magneto-optical crystal, and the rotation angle of the polarization direction of linear polarized light is 22.5 degrees; the first Faraday rotator and the second Faraday rotator are of the same size; the first lens and the second lens are of the same size and material; the input light splitting / combining device is of the same size as the first output light splitting / combining device and the second output light splitting / combining device.

8. The high isolation optical splitter according to claim 1, characterized in that: The magnetic ring is a permanent magnet, which is used to provide the saturation magnetic field intensity of the magneto-optical crystal, so that the magneto-optical crystal can realize fixed rotation of the polarization direction of linearly polarized light; the direction of the magnetic field is parallel to the direction of light propagation; when the linearly polarized light is incident from the N-level magnetic field formed by the magnetic ring, the polarization direction rotates clockwise; when the linearly polarized light is incident from the S-level magnetic field, the polarization direction rotates counterclockwise; the beam splitter is a flat glass plate, and the beam splitting surface is coated with a beam splitting power TAP film or a beam splitting wavelength WDM film.

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