CN214669708U - Prism assembly for polarization light splitting, four-port circulator and coherent BIDI optical module - Google Patents

Abstract

The utility model relates to a prism subassembly for polarization beam split, including parallel first polarization beam splitter and the polarization beam splitter of second that the interval was laid, first polarization beam splitter and the polarization beam splitter of second all include right angle triangle prism and the parallelogram prism of veneer, and the cemented surface of right angle triangle prism and parallelogram prism is the PBS face, two PBS face parallel arrangement, and first polarization beam splitter and second polarization beam splitter all have two ports that supply optical signal input and/or output. A four-port circulator is also provided, comprising the prism assembly for polarization splitting. A coherent BIDI optical module is also provided, including the four-port circulator. The utility model discloses a PBS polarization beam splitting right angle triangle prism and PBS polarization beam splitting parallelogram prism glue two polarization beam splitting prisms, provide a plurality of and throw face, plane of reflection to realized multiport light path output, realized the simple and easy transmission of the port of a plurality of receiving chip.

Description

Prism assembly for polarization light splitting, four-port circulator and coherent BIDI optical module

Technical Field

The utility model relates to a circulator technical field specifically is a prism subassembly, four port circulator and coherent BIDI optical module for polarization beam split.

Background

When data transmission is performed by an existing optical module, data transmission is performed mostly through two optical fibers, one of the optical fibers is used for receiving data from a network device, and the other optical fiber is used for transmitting data to the network device. The wavelength of the filter must be complemented and used in pairs when the optical module is used, and the operating wavelengths of the two BiDi optical modules must be complemented and matched, so that the use is limited. The coherent detection technology needs a multi-channel modulation-demodulation balanced detection combination, and a common 3-port circulator cannot realize the light path transmission of more channels, so that the realization of coherent detection is limited.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a prism subassembly, four port circulator and relevant BIDI optical module for polarization beam split adopts PBS polarization beam splitting right angle triangle prism and PBS polarization beam splitting parallelogram prism to glue two polarization beam splitting prisms, provides a plurality of and throws face, plane of reflection to realized multiport light path output, realized the simple and easy transmission of the port of a more receiving chip.

In order to achieve the above object, the embodiment of the present invention provides the following technical solutions: the utility model provides a prism subassembly for polarization beam splitting, includes first polarization beam splitting prism and the polarization beam splitting prism of second that parallel and interval were laid, first polarization beam splitting prism with second polarization beam splitting prism all includes right angle triangle prism and the parallelogram prism of veneer, right angle triangle prism with the cemented surface of parallelogram prism is PBS face, two PBS face parallel arrangement, first polarization beam splitting prism with second polarization beam splitting prism all has two ports that supply optical signal input and/or output.

Furthermore, the surface of each parallelogram prism, which is opposite to the right-angle triangular prism glued with the parallelogram prism, is a total reflection surface.

Further, the parallelogram prism and the right-angle triangular prism are glued to form a flat combined surface, the combined surface is a light-transmitting surface, and the surface of the first polarization beam splitter prism parallel to the combined surface and the surface of the second polarization beam splitter prism parallel to the combined surface are both light-transmitting surfaces.

Furthermore, two ports of the first polarization beam splitter prism are respectively an incident port and a first exit port, two ports of the second polarization beam splitter prism are respectively a compatible port and a second exit port, and the compatible port has input and output; the optical signal incident from the incident port is emitted from the compatible port, and the optical signal incident from the compatible port is emitted from the first exit port and the second exit port respectively.

Further, the length of the parallelogram prism of the second polarization splitting prism is greater than that of the parallelogram prism of the first polarization splitting prism, and the second exit port is located at a position where the parallelogram prism of the second polarization splitting prism exceeds the parallelogram prism of the first polarization splitting prism.

Furthermore, the incident port and the first exit port are located on the same side of the first polarization beam splitter prism, the compatible port and the second exit port are located on the opposite sides of the second polarization beam splitter prism, and the incident port, the first exit port and the second exit port are located on the same side of the second polarization beam splitter prism.

The embodiment of the utility model provides another kind of technical scheme: the four-port circulator comprises the prism assembly for polarization splitting, and isolators are arranged at ports of the first polarization splitting prism and the second polarization splitting prism, which are used for outputting optical signals.

Further, a faraday rotation piece is arranged between the first polarization beam splitter prism and the second polarization beam splitter prism.

Further, a first half-wave plate is arranged between the first polarization beam splitter prism and the second polarization beam splitter prism, and the direction from the first half-wave plate to the Faraday magnetic rotation plate is consistent with the direction from the first polarization beam splitter prism to the second polarization beam splitter prism.

The embodiment of the utility model provides another kind of technical scheme: a coherent BIDI optical module includes the four-port circulator.

Compared with the prior art, the invention has the beneficial effects that:

1. by the circulator with four ports, more port outputs are provided compared with a three-port circulator, transmission of one more optical path is realized, and application of a coherent technology is realized.

2. The isolator and the half-wave plate are added, so that the stray light signal can be effectively prevented from returning to the transmitting chip, the isolation degree of the incident port and the compatible port is increased, the influence of the stray light on the transmitting chip is reduced, and the influence of the whole light path on transmission of the stray light signal is further reduced.

3. The PBS polarization beam splitting right-angle triangular prism and the PBS polarization beam splitting parallelogram prism are glued to form two polarization beam splitting prisms, and a plurality of light passing surfaces and reflecting surfaces are provided, so that multi-port light path output is realized, and simple transmission of one more receiving chip port is realized.

4. The magnetic block is adopted to replace a magnetic ring, so that all devices can be borne, the assembly difficulty is reduced, the size is reduced, the reliability is improved, and the performance is more stable.

5. The light-transmitting surfaces of the devices are bonded with glue films or are bonded by adopting glue with matched refractive index without gaps, the stability is good, the light path loss of the transmittance of the optical signals is increased, so that the IL (insertion loss) performance is improved, the reflection of the optical signals to the light of the air output surface is reduced, the RL (return loss) performance is improved, and the integral volume is reduced.

6. The heights of the first polarization beam splitter prism and the second polarization beam splitter prism can be increased or reduced, so that the distances among the incident port, the first exit port and the second exit port can be increased or reduced and adjusted.

Drawings

FIG. 1 is a perspective view of a four port circulator with multiple isolators according to an embodiment of the present invention;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a schematic diagram of the first and second polarization beam-splitting prisms of FIG. 1;

in the reference symbols: 1-a second polarization beam splitter prism; 2-faraday rotator; 3-a first half wave plate; 4-a first polarization beam splitter prism; 5-a second half-wave plate; 6-a first isolator; 7-a second isolator; 8-a third isolator; 9-a magnetic block; 10-a parallelogram prism; 11-a right-angled triangular prism; 12-an entrance port; 13-a compatible port; 14-a first exit port; 15-second exit port.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 and fig. 2, an embodiment of the present invention provides a four-port circulator with multiple isolators, including four ports, one of which is an incident port 12, one of which is a compatible port 13 with input and output, and the other two of which are exit ports, where the isolators are installed at both the exit ports; the optical signal incident from the incident port 12 is emitted from the compatible port 13, and the optical signal incident from the compatible port 13 is emitted from each of the two exit ports. In the embodiment, the circulator with four ports has more port outputs than the circulator with three ports, so that transmission of one more optical path is realized, and application of a coherent technology is realized. One of the four ports is a single incident port 12, two of the four ports are single exit ports, the remaining one port has both input and output, a transmitting chip is arranged at the port of the incident port 12, light output by the transmitting chip is input from the incident port 12, receiving chips are arranged at the ports of the two exit ports to receive a light signal transmitted by another transmitting module, the compatible port 13 is used as an optical fiber transmission interface, when the circulator is used in a transmitting optical module, the compatible port 13 transmits the light signal transmitted from the incident port 12 to be used as an exit port, and when the circulator is used in a receiving optical module, the compatible port 13 transmits the received light signal to be sent to the two exit ports (i.e. a first exit port 14 and a second exit port 15) to be used as the incident ports, thereby realizing a single fiber bidirectional transmission technology, i.e., the BiDi technique. When the circulator is used in an optical module, usually two optical modules are used in combination, when the compatible port 13 of the circulator of one optical module is used as an incident port, the compatible port 13 of the circulator of the other adjacent optical module is used as an emergent port, the optical module used as the incident port is a receiving optical module, and the optical module used as the emergent port is a transmitting optical module.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1 and fig. 2, the circulator further includes a first polarization splitting prism 4 and a second polarization splitting prism 1 which are arranged in parallel at intervals, the entrance port 12 and one of the exit ports are both arranged close to the first polarization splitting prism 4, and the compatible port 13 and the other exit port are both arranged close to the second polarization splitting prism 1. In this embodiment, the four ports are attached to the polarization beam splitter prism, and the first polarization beam splitter prism 4 and the second polarization beam splitter prism 1 provide a plurality of light-passing surfaces and reflecting surfaces, so that multi-port optical path output is realized, and simple transmission of one more receiving chip port is realized. Specifically, two polarization splitting prisms are spaced and arranged in parallel, and the multi-surface characteristic of the prisms can enable the whole structure to form a plurality of light paths, so that a plurality of ports are realized.

In order to optimize the above scheme, please refer to fig. 1 and fig. 2, the incident port 12 and one of the exit ports are respectively located on the same side of the polarization beam splitter prism, the compatible port 13 and the other exit port are respectively located on an opposite side of the polarization beam splitter prism, and the incident port 12 and the two exit ports are both located on the same side of the second polarization beam splitter prism 1. In this embodiment, the specific locations of several ports are refined. Wherein, the entrance port 12 and one of the exit ports are respectively located on the same side of the first polarization beam splitter prism 4, while the compatible port 13 and the other exit port are respectively located on the opposite side of the second polarization beam splitter prism 1, and as a whole, the entrance port 12 and the two exit ports are both located on the same side of the second polarization beam splitter prism 1. Thus, after the P-polarized light input from the incident port 12 enters the first polarization splitting prism 4, the polarization state is not changed through the rotation of the opposite direction of the faraday and the optical rotation sheet, the P-polarized light is transmitted to the PBS surface of the second polarization splitting prism 1 and output from the compatible port 13, which is the transmission direction of the first light and relates to two ports, and the light input from the compatible port 13 has two polarization states, and after entering the second polarization splitting prism 1, one of the S-polarized light is reflected and transmitted on the PBS surface of the second polarization splitting prism 1 and finally output from the port arranged on the second polarization splitting prism 1, which is the transmission direction of the second light and also relates to two ports, and the other P-polarized light is transmitted from the second polarization splitting prism 1 and then undergoes the rotation of the faraday and the optical rotation sheet in the same direction, so that the polarization state is changed into S-polarized light, and then reflected by the PBS surface of the first polarization splitting prism 4, transmitted in the first polarization splitting prism 4, and finally output from an exit port provided on the first polarization splitting prism 4, which is the transmission direction of the third light, and at this time, two ports are also involved. Of course, in addition to the above, the position of the ports is not limited to the above example, and the positions and angles thereof can be adjusted, but the four-port design is not known in the prior art, and has more beneficial effects than the three-port design.

Referring to fig. 1 and 2 as an optimized solution of the embodiment of the present invention, a faraday rotator 2 is disposed between the first polarization beam splitter 4 and the second polarization beam splitter 1. Preferably, a first half-wave plate 3 is further disposed between the first polarization splitting prism 4 and the second polarization splitting prism 1, and a direction from the first half-wave plate 3 to the faraday rotation plate 2 is consistent with a direction from the first polarization splitting prism 4 to the second polarization splitting prism 1. In this embodiment, the optical signal is reflected by the first polarization splitting prism 4 and output from the exit port, and the optical signal cannot be output from the entrance port 12, by the rotation of the faraday rotation plate 2 and the first half-wave plate 3. Preferably, the rotation angle of the polarization state of light passing through the faraday rotator 2 is preferably 45 degrees.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1 and fig. 2, an isolator is also installed at the entrance port 12. In this embodiment, the input port 12 is also provided with an isolator, and thus the whole circulator has three isolators, for the sake of convenience of marking, the isolator of the input port 12 is defined as the first isolator 6, the isolator of the output port of the first polarization splitting prism 4 is defined as the second isolator 7, and the isolator of the output port of the second polarization splitting prism 1 is defined as the third isolator 8, which are both used for preventing the stray light signal from returning to the initial position. Preferably, a second half-wave plate 5 is disposed between the isolator at the entrance port 12 and the first polarization splitting prism 4, where the second half-wave plate 5 has the same effect as the first half-wave plate 3, and will not be described herein again. When the separator at the entrance 12 is a bipolar separator, the second half-wave plate 5 may not be needed.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1, where the first polarization beam splitter 4, the second polarization beam splitter 1, and the isolators at the two exit ports are all disposed on a magnetic block 9. In this embodiment, the magnetic block 9 can bear all devices, so that the assembly difficulty is reduced, the size is reduced, the reliability is improved, and the performance is more stable. Specifically, in addition to the first polarization splitting prism 4, the second polarization splitting prism 1, and the isolators at the two exit ports, all the devices mentioned in the above embodiments, such as the first isolator 6, the first half-wave plate 3, the second half-wave plate 5, and the faraday rotation plate 2, can be disposed on the magnetic block 9, which is the most different point from the existing magnetic ring. Before the device is arranged, the devices can be fixed in a gluing mode, then are integrally bonded on the magnetic block 9, and can be bonded one by one after being positioned, and both the devices and the magnetic block are feasible technical schemes. And the light-transmitting surfaces of all devices are bonded with glue films again or are bonded by adopting glue with matched refractive index without gaps, so that the stability is good, the light path loss of the transmittance of an optical signal is increased, the IL (insertion loss) performance is improved, the reflection of the optical signal to the light of the air output surface is reduced, the RL (return loss) performance is improved, and the devices are bonded together in advance and then integrally bonded on the magnetic block 9, so that the precision and the preparation efficiency can be improved. The magnet block 9 is also adopted, so that the size is greatly reduced compared with the existing multiple magnet rings. Preferably, the magnetic block 9 is made of neodymium iron boron magnet or similar permanent magnet, and the effective magnetic field intensity is as follows: 1000Gs gauss, so that a better effect can be achieved.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1 and fig. 2, heights between the first polarization splitting prism 4 and the second polarization splitting prism 1 are both adjustable. In this embodiment, the heights of the first polarization splitting prism 4 and the second polarization splitting prism 1 themselves can be increased or decreased, so that the distances of the incident port, the first exit port and the second exit port can be increased or decreased and adjusted.

Referring to fig. 1 and 2, an embodiment of the invention provides a coherent BIDI optical module including the four-port circulator with a plurality of isolators. In this embodiment, the four-port circulator is used in a coherent BIDI optical module, and the circulator with four ports has more port outputs than the three-port circulator, so that transmission of one more optical path is realized, and application of a coherent technology is realized. One of the four ports is a single incident port 12, two of the four ports are single exit ports, the remaining one port has both input and output, a transmitting chip is arranged at the port of the incident port 12, light output by the transmitting chip is input from the incident port 12, receiving chips are arranged at the ports of the two exit ports to receive a light signal transmitted by another transmitting module, the compatible port 13 is used as an optical fiber transmission interface, when the circulator is used in a transmitting optical module, the compatible port 13 transmits the light signal transmitted from the incident port 12 to be used as an exit port, and when the circulator is used in a receiving optical module, the compatible port 13 transmits the received light signal to be sent to the two exit ports (i.e. a first exit port 14 and a second exit port 15) to be used as the incident ports, thereby realizing a single fiber bidirectional transmission technology, i.e., the BiDi technique. When the circulator is used in coherent BIDI optical modules, two coherent BIDI optical modules are usually used in a matching way, when the compatible port 13 of the circulator of one coherent BIDI optical module is used as an incident port, the compatible port 13 of the circulator of the other coherent BIDI optical module adjacent to the compatible port is used as an emergent port, the coherent BIDI optical module used as the incident port is a light receiving module, and the coherent BIDI optical module used as the emergent port is a light emitting module.

Referring to fig. 1 and 2, an embodiment of the present invention provides a prism assembly for polarization splitting, including a first polarization splitting prism 4 and a second polarization splitting prism 1 that are arranged in parallel and at an interval, where the first polarization splitting prism 4 and the second polarization splitting prism 1 both include a right-angle triangular prism 11 and a parallelogram prism 10 that are glued together, the glued surfaces of the right-angle triangular prism 11 and the parallelogram prism 10 are PBS surfaces, the two PBS surfaces are arranged in parallel, and the first polarization splitting prism 4 and the second polarization splitting prism 1 both have two ports for inputting and/or outputting optical signals. In this embodiment, the PBS polarizing right-angle triangular prism 11 and the PBS polarizing parallelogram prism 10 are bonded to form two polarizing beam splitting prisms, and a plurality of light-passing surfaces and reflecting surfaces are provided, so that multi-port light path output is realized, and simple transmission of one more receiving chip port is realized. The right-angle triangular prism 11 and the parallelogram prism 10 are glued at the PBS surface to form a whole, as can be seen from FIG. 2, the gap at the lower part of the parallelogram prism 10 is filled by the right-angle triangular prism 11 to form a square structure, the bottoms of the two polarization splitting prisms are aligned, and light can pass through the square structure. Please refer to fig. 3, which is a schematic diagram of the first polarization splitting prism 4 and the second polarization splitting prism 1, which are different in size, and therefore are illustrated by using one drawing, for convenience of labeling, two PBS planes are defined as S4 planes, and the two PBS planes can implement polarization splitting, so that the prism assembly is used in a circulator to form a circulator with more ports. Preferably, the PBS surface can realize polarization splitting by plating a PBS mode, namely P light transmission and S light reflection, and the multilayer dielectric film meets the Brewster condition.

Referring to fig. 1, 2 and 3, as an optimization scheme of the embodiment of the present invention, a surface of each parallelogram prism 10 facing the right-angle triangular prism 11 glued thereto is a total reflection surface. In the present embodiment, for convenience of labeling, two total reflection surfaces are defined as S2 surfaces, and the two surfaces are total reflection surfaces to facilitate the output of the optical signals from the two exit ports.

Referring to fig. 1, 2 and 3 as an optimization scheme of the embodiment of the present invention, the parallelogram prism 10 and the right-angle triangular prism 11 are glued to form a flat combined surface, the combined surface is a light-transmitting surface, and both a surface of the first polarization beam splitter prism 4 parallel to the combined surface and a surface of the second polarization beam splitter prism 1 parallel to the combined surface are light-transmitting surfaces. In the present embodiment, for convenience of reference, the combined surfaces are defined as S3 surfaces and S5 surfaces, where the S3 surface is a surface on the parallelogram prism 10, the S5 surface is a surface on the right-angle triangular prism 11, and the surface parallel to the combined surface is defined as the S1 surface, and the S1 surface, the S3 surface, and the S5 surface are all clear surfaces. Preferably, the bottom surfaces of the parallelogram prism 10 and the right-angle triangular prism 11 are respectively an S6 surface and an S7 surface, which are both adhesive surfaces capable of being adhered to the magnetic block 9. Preferably, the S1 side is not connected to the part, faces air, and is AR coated.

As an optimization scheme of the embodiment of the present invention, please refer to fig. 1 and fig. 2, two ports of the first polarization splitting prism 4 are an incident port 12 and a first exit port 14, two ports of the second polarization splitting prism 1 are a compatible port 13 and a second exit port 15, and the compatible port 13 has both input and output; the optical signal incident from the incident port 12 is emitted from the compatible port 13, and the optical signal incident from the compatible port 13 is emitted from the first exit port 14 and the second exit port 15, respectively. In the embodiment, one of the four ports is a single incident port 12, two ports are single exit ports, and the remaining one port has both input and output, a transmitting chip is disposed at the port of the incident port 12, light output by the transmitting chip is input from the incident port 12, receiving chips are disposed at the ports of the two exit ports to receive optical signals transmitted from another transmitting module, the compatible port 13 is used as an optical fiber transmission interface, when the circulator is used in a transmitting optical module, the compatible port 13 transmits the optical signals transmitted from the incident port 12 to be used as an exit port, and when the circulator is used in a receiving optical module, the compatible port 13 transmits the received optical signals to be sent to the two exit ports (i.e. the first exit port 14 and the second exit port 15) to be used as the incident ports, thereby implementing a single fiber bidirectional transmission technology, i.e., the BiDi technique. When the circulator is used in coherent BIDI optical modules, two coherent BIDI optical modules are usually used in a matching way, when the compatible port 13 of the circulator of one coherent BIDI optical module is used as an incident port, the compatible port 13 of the circulator of the other coherent BIDI optical module adjacent to the compatible port is used as an emergent port, the coherent BIDI optical module used as the incident port is a light receiving module, and the coherent BIDI optical module used as the emergent port is a light emitting module.

To further optimize the above solution, please refer to fig. 1 and fig. 2, a length of the parallelogram prism 10 of the second polarization splitting prism 1 is greater than a length of the parallelogram prism 10 of the first polarization splitting prism 4, and the second exit port 15 is located at a position where the parallelogram prism 10 of the second polarization splitting prism 1 exceeds the parallelogram prism 10 of the first polarization splitting prism 4. In the present embodiment, as can be seen from fig. 2, the length of the parallelogram prism 10 of the second polarization splitting prism 1 is greater than the length of the parallelogram prism 10 of the first polarization splitting prism 4, so when the two polarization splitting prisms are aligned at the bottom, the parallelogram prism 10 of the second polarization splitting prism 1 is beyond the parallelogram prism 10 of the first polarization splitting prism 4, and the second exit port 15 is provided there, so that the occurrence of interference can be avoided.

As an optimized solution of the embodiment of the present invention, please refer to fig. 1 and fig. 2, the incident port 12 and the first exit port 14 are respectively located on the same side of the first polarization splitting prism 4, the compatible port 13 and the second exit port 15 are respectively located on an opposite side of the second polarization splitting prism 1, and the incident port 12, the first exit port 14 and the second exit port 15 are all located on the same side of the second polarization splitting prism 1. In this embodiment, the specific locations of several ports are refined. Wherein, the entrance port 12 and one of the exit ports are respectively located on the same side of the first polarization beam splitter prism 4, while the compatible port 13 and the other exit port are respectively located on the opposite side of the second polarization beam splitter prism 1, and as a whole, the entrance port 12 and the two exit ports are both located on the same side of the second polarization beam splitter prism 1. Thus, after the P-polarized light input from the incident port 12 enters the first polarization splitting prism 4, the polarization state is not changed through the rotation of the opposite direction of the faraday and the optical rotation sheet, the P-polarized light is transmitted to the PBS surface of the second polarization splitting prism 1 and output from the compatible port 13, which is the transmission direction of the first light and relates to two ports, and the light input from the compatible port 13 has two polarization states, and after entering the second polarization splitting prism 1, one of the S-polarized light is reflected and transmitted on the PBS surface of the second polarization splitting prism 1 and finally output from the port arranged on the second polarization splitting prism 1, which is the transmission direction of the second light and also relates to two ports, and the other P-polarized light is transmitted from the second polarization splitting prism 1 and then undergoes the rotation of the faraday and the optical rotation sheet in the same direction, so that the polarization state is changed into S-polarized light, and then reflected by the PBS surface of the first polarization splitting prism 4, transmitted in the first polarization splitting prism 4, and finally output from an exit port provided on the first polarization splitting prism 4, which is the transmission direction of the third light, and at this time, two ports are also involved. Of course, in addition to the above, the position of the ports is not limited to the above example, and the positions and angles thereof can be adjusted, but the four-port design is not known in the prior art, and has more beneficial effects than the three-port design.

As an optimized solution of the embodiment of the present invention, the first polarization splitting prism 4, the second polarization splitting prism 1, the faraday rotation plate 2, the first half-wave plate 3, the second half-wave plate 5, the first isolator 6, the second isolator 7, and the third isolator 8 are all assembled by glue bonding, the bonding form is that adjacent devices are bonded, and the bonded surfaces are all light-passing surfaces. Preferably, the glue bonding mode, whether the devices are bonded, or the devices are bonded on the magnetic block 9, or the parallelogram prism 10 and the right-angle triangle prism 11, can be performed after the glue is coated, or can be performed by adopting glue with matched refractive index. Thus, no separated gap can be ensured, and the optical path loss is small.

Referring to fig. 2 as an optimized solution of the embodiment of the present invention, a transmission path of an optical path in a device is as follows:

light signals P are incident to the compatible port 13 from the incident port 12, the P light is transmitted through the S4 polarization splitting plane of the first polarization splitting prism 4, the optical rotation directions of the P light passing through the first half wave plate 3 and the Faraday magnetic rotation plate 2 are opposite, the P light is not changed, and the S4 polarization splitting plane reaching the second trapezoidal polarization splitting prism is transmitted and output from the compatible port 13;

if a P optical signal is input from the compatible port 13, and the P light is transmitted through the S4 polarization splitting surface of the second trapezoidal polarization splitting prism, the magnetic pole of the magnetic block 9 is reversed, and the P light is changed into S light through the rotation of the faraday rotation piece 2 and the first half wave plate 3 in the same direction, the S optical signal cannot be transmitted out of the S4 polarization splitting surface of the first polarization splitting prism 4, and only can be reflected, and then reaches the first exit port 14 through the reflection of the S2 polarization splitting surface, and the first isolator 6 can make other stray light signals also cannot be output from the entrance port 12, so that the isolation degree is increased;

if the optical signal S light is incident from the optical transmission port of the compatible port 13, the S light is reflected by the S4 polarization splitting surface of the second trapezoidal polarization splitting prism, and then reflected by the S2 total reflection surface of the second polarization splitting prism 1, and is output from the second exit port 15 of the S3 surface, that is, an output optical signal of one port is added from the compatible port 13 to the second exit port 15, and further, the light cannot be output from the compatible port 13 to the incident port 12. It is demonstrated that the optical signal input from the compatible port 13 can only be output from the first exit port 14 and the second exit port 15, but not from the incident port 12, so as to achieve the purpose of unidirectional transmission of the optical signal, and at the same time, the output optical signal of the second exit port 15 of one receiving port is added, and at the same time, the second isolator 7 and the third isolator 8 are added to the first exit port 14 and the second exit port 15 respectively, so as to effectively prevent the stray light signal returning from the receiving apparatus from being isolated, and reduce the influence of the stray light signal in the whole optical path transmission.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. A prism assembly for polarization splitting, comprising: including parallel and first polarization beam splitting prism and the polarization beam splitting prism of second of laying at interval, first polarization beam splitting prism with second polarization beam splitting prism all includes right angle triangle prism and the parallelogram prism of veneer, right angle triangle prism with the veneer surface of parallelogram prism is PBS face, two PBS face parallel arrangement, first polarization beam splitting prism with second polarization beam splitting prism all has two ports that supply optical signal input and/or output.

2. The prism assembly for polarization splitting according to claim 1, wherein: the surface of each parallelogram prism, which is opposite to the right-angle triangular prism glued by the parallelogram prisms, is a total reflection surface.

3. The prism assembly for polarization splitting according to claim 1, wherein: the parallelogram prism and the right-angle triangular prism are glued to form a flat combined surface, the combined surface is a light-transmitting surface, and the surface of the first polarization beam splitter prism parallel to the combined surface and the surface of the second polarization beam splitter prism parallel to the combined surface are both light-transmitting surfaces.

4. The prism assembly for polarization splitting according to claim 1, wherein: the two ports of the first polarization beam splitter prism are respectively an incident port and a first emergent port, the two ports of the second polarization beam splitter prism are respectively a compatible port and a second emergent port, and the compatible port has input and output; the optical signal incident from the incident port is emitted from the compatible port, and the optical signal incident from the compatible port is emitted from the first exit port and the second exit port respectively.

5. The prism assembly for polarization splitting according to claim 4, wherein: the length of the parallelogram prism of the second polarization splitting prism is greater than that of the parallelogram prism of the first polarization splitting prism, and the second exit port is positioned at a position where the parallelogram prism of the second polarization splitting prism exceeds the parallelogram prism of the first polarization splitting prism.

6. The prism assembly for polarization splitting according to claim 4, wherein: the incident port and the first exit port are respectively located on the same side of the first polarization beam splitter prism, the compatible port and the second exit port are respectively located on the opposite side of the second polarization beam splitter prism, and the incident port, the first exit port and the second exit port are located on the same side of the second polarization beam splitter prism.

7. A four-port circulator, comprising: the prism assembly for polarization beam splitting comprises the prism assembly for polarization beam splitting as claimed in any one of claims 1 to 6, wherein the ports of the first polarization beam splitting prism and the second polarization beam splitting prism for optical signal output are provided with isolators.

8. The four-port circulator of claim 7 further comprising: and a Faraday magnetic rotation sheet is arranged between the first polarization beam splitter prism and the second polarization beam splitter prism.

9. The four-port circulator of claim 8 wherein: and a first half-wave plate is arranged between the first polarization beam splitter prism and the second polarization beam splitter prism, and the direction from the first half-wave plate to the Faraday magnetic rotation plate is consistent with the direction from the first polarization beam splitter prism to the second polarization beam splitter prism.

10. A coherent BIDI optical module, characterized by: comprising the four-port circulator of claim 7.

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