Low-cost multi-port optical circulator

Abstract

The utility model relates to a low-cost multi-port optical circulator, which comprises a rhombic prism, a first polarization splitting prism, a first half-wave plate, a second half-wave plate, a first Faraday optical rotation crystal, a second Faraday optical rotation crystal, a second polarization splitting prism and a turning prism. The five-channel multi-stage isolation optical circulator is a low-cost optical circulator capable of realizing five-channel multi-stage isolation, meets higher requirements of an optical communication module on isolation, insertion loss and return loss, and ensures return loss gt of each channel; in addition, input light and output light of the four ports are kept parallel, coupling adjustment of the coupler is facilitated, design is simple, manufacturing is easy, good stability and reliability are achieved, and the requirement for isolation among different ports can be remarkably improved when the coupler is applied to an optical network system.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber communication, in particular to a low-cost multi-port optical circulator. Background Art

[0002] In modern optical communications and photonic integrated circuit (PIC) systems, optical circulators are core components that use the Faraday magneto-optical effect to achieve directional propagation of multi-port input and output at specific wavelengths. When the transmission order of the signal light is changed, that is, when it is not transmitted according to the specified port, its loss is very large, which can achieve isolation of the input signal. Traditional optical circulators are mainly based on three-port or multiple three-port cascade designs, and the isolation between different ports is either achieved through a single circulator core to achieve single-stage isolation, or through a circulator core array to achieve multi-stage isolation, or by adding additional optical isolators to the circulator structure to achieve the purpose of multi-stage isolation, which limits the cost and assembly space of the optical module, and limits the optical performance selection space and application in high-performance optical networks. Summary of the invention

[0003] In view of the above problems, the purpose of the present invention is to provide a low-cost multi-port optical circulator to solve the problems of insufficient isolation and multi-port application of traditional optical circulators.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A low-cost multi-port optical circulator comprises an rhombus prism, a first polarization beam splitter prism, a first half-wave plate, a second half-wave plate, a first Faraday rotator crystal, a second Faraday rotator crystal, a second polarization beam splitter prism and a turning prism;

[0006] The cross section of the rhombus prism is a parallelogram structure, which is used to change the transmission direction of the signal light;

[0007] The cross section of the first polarization beam splitter prism is an isosceles trapezoidal structure, and a first polarization beam splitter film and a second polarization beam splitter film are arranged inside the first polarization beam splitter prism, which is divided into three parts: upper, middle and lower parts;

[0008] The cross section of the second polarization beam splitter prism is a right-angled trapezoidal structure with a base angle of 45°, and a third polarization beam splitter film and a fourth polarization beam splitter film are arranged inside the second polarization beam splitter prism, which is divided into three parts: upper, middle and lower parts;

[0009] The cross section of the turning prism is an isosceles right triangle structure, which is used to reflect the signal light and make a 180° turn in the transmission direction of the signal light;

[0010] The first polarization beam splitter prism and the second polarization beam splitter prism are used to input or output signal light, and the first polarization beam splitter film, the second polarization beam splitter film, the third polarization beam splitter film and the fourth polarization beam splitter film are used to separate or synthesize P-polarized light and S-polarized light in the signal light; the first half-wave plate and the first Faraday rotator crystal are bonded together, and the second half-wave plate and the second Faraday rotator crystal are bonded together, and are both used to perform 90° polarization rotation on the signal light in a single transmission direction, and not perform polarization rotation on the signal light in another transmission direction;

[0011] The right end faces of the upper and lower parts of the cross section of the first polarization beam splitter prism are respectively bonded to one end face of the first half-wave plate and the second half-wave plate, the first polarization beam splitter film is at a 90° angle to the upper end face of the upper part of the first polarization beam splitter prism, the first polarization beam splitter film is parallel to the lower end face of the lower part of the first polarization beam splitter prism, and the upper end face of the upper part and the lower end face of the lower part of the first polarization beam splitter prism are both provided with high reflection films. The second polarization beam splitter film is parallel to the first polarization beam splitter film. The first half-wave plate is bonded to one end face of the first Faraday rotator crystal, and the second half-wave plate is bonded to one end face of the second Faraday rotator crystal. The upper part of the second polarization beam splitter prism is bonded to the other end face of the first Faraday rotator crystal, and the lower part of the second polarization beam splitter prism is bonded to the other end face of the second Faraday rotator crystal; the third polarization beam splitter film forms an angle of 45° with the upper end face of the upper part of the second polarization beam splitter prism, the third polarization beam splitter film forms an angle of 45° with the lower end face of the lower part of the second polarization beam splitter prism, the fourth polarization beam splitter film is parallel to the third polarization beam splitter film, the upper end face of the upper part of the second polarization beam splitter prism is provided with a high reflection film, and the lower end face of the lower part of the second polarization beam splitter prism is provided with a high reflection film. There is a high-transmittance film; the lower end face of the lower part of the second polarization beam splitter prism is in contact with the end face where the long bottom edge of the turning prism is located; the signal port Prot1 is located on the right end face of the upper part of the first polarization beam splitter prism, the signal port Prot2 is located on the left end face of the middle part of the first polarization beam splitter prism, the signal port Prot3 is located on the left end face of the rhombus prism, the signal port Prot4 is located on the right end face of the upper part of the second polarization beam splitter prism, and the signal port Port5 is located on the right end face of the middle part of the second polarization beam splitter prism.

[0012] Further, the positions of the first half-wave plate and the first Faraday rotator crystal can be interchanged, and the positions of the second half-wave plate and the second Faraday rotator crystal can be interchanged.

[0013] Furthermore, all the bonding surfaces and signal port surfaces are provided with anti-reflection films.

[0014] Furthermore, the angle at which the signal light enters the optical circulator is 1 to 5 degrees.

[0015] The utility model adopts the above technical solution and is a low-cost optical circulator that can achieve five-channel multi-level isolation, meet the optical communication module (transceiver) higher requirements for isolation, insertion loss and return loss, ensure that the return loss of each channel is >50dB, and the input and output lights of the four ports remain parallel, which is convenient for the coupler to adjust the coupling, and has a simple design, easy to manufacture, good stability and reliability. Its application in optical network systems can significantly improve the isolation requirements between different ports. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific implementations:

[0017] Figure 1 A schematic diagram of a simplified implementation structure of the optical circulator of Example 1;

[0018] Figure 2 Schematic diagram of light propagation of signal light from Port 1 to the turning prism based on Example 1;

[0019] Figure 3 It is a schematic diagram of light propagation of an optical signal based on Example 1, which propagates from Port 1 to the turning prism and then propagates from the folding prism to Port 2 and Port 3;

[0020] Figure 4 Schematic diagram of light propagation of signal light from Port 2 to Port 4 based on Example 1;

[0021] Figure 5 This is a schematic diagram of light propagation of signal light from Port 2 to Port 5 based on Example 1;

[0022] Figure 6 It is a light propagation schematic diagram of the signal light from Port3 to Port4 and Port5 based on Example 1;

[0023] Figure 7 Schematic diagram of the optical path of a five-port optical circulator based on a single fiber collimator in Example 2;

[0024] Figure 8 This is a schematic diagram of the optical path of a two-in-one five-port optical circulator based on a dual-fiber collimator according to Example 3;

[0025] Fig. 9 is a schematic diagram of a miniaturized five-port optical circulator based on an optical port according to Example 4;

[0026] In all the drawings, the same reference numerals represent the same technical features, specifically:

[0027] The short double-headed arrows indicate the P polarization state, and the dots indicate the S polarization state. DETAILED DESCRIPTION

[0028] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0029] Please refer to Figure 1 A five-port optical circulator provided in this embodiment 1 includes an rhombus prism 101, a first polarization beam splitter prism 102, a first half-wave plate 103, a second half-wave plate 104, a first Faraday rotator crystal 106, a second Faraday rotator crystal 105, a turning prism 107, and a second polarization beam splitter prism 108;

[0030] The first half-wave plate 103 and the second half-wave plate 104 are respectively combined with the first Faraday rotator crystal 106 and the second Faraday rotator crystal 105 to form an optical rotation mechanism, and the polarization direction of the light is rotated by 90° when the light propagates from left to right, and the polarization direction is not rotated when the light propagates from right to left;

[0031] The cross section of the rhombus prism 101 is a parallelogram structure, and is used to change the transmission direction of the signal light;

[0032] The cross section of the first polarization beam splitter prism 102 is an isosceles trapezoidal structure, and a first polarization beam splitter film 1011 and a second polarization beam splitter film 1012 are arranged inside the first polarization beam splitter prism 102, which is divided into three parts: upper, middle and lower parts;

[0033] The cross section of the second polarization beam splitter prism 108 is a right-angled trapezoidal structure with a base angle of 45°, and a third polarization beam splitter film 1013 and a fourth polarization beam splitter film 1014 are arranged inside the second polarization beam splitter prism 108, which is divided into three parts: upper, middle and lower parts;

[0034] The cross section of the turning prism 107 is an isosceles right triangle structure, which is used to reflect the signal light and make a 180° turn in the transmission direction of the signal light;

[0035] The first polarization beam splitter prism 102 and the second polarization beam splitter prism 108 are used to input or output signal light, and the first polarization beam splitter film 1011, the second polarization beam splitter film 1012, the third polarization beam splitter film 1013 and the fourth polarization beam splitter film 1014 are used to separate or synthesize P polarized light and S polarized light in the signal light;

[0036] The first half-wave plate 103 and the first Faraday rotator crystal 106 are bonded together, and the second half-wave plate 104 and the second Faraday rotator crystal 105 are bonded together, and are used to perform 90° polarization rotation on the signal light in a single transmission direction, while not performing polarization rotation on the signal light in another transmission direction;

[0037] The right end faces of the upper and lower parts of the cross section of the first polarization beam splitter prism 102 are respectively bonded to the first half-wave plate 103 and one end face of the second half-wave plate 104. The first polarization beam splitter film 1011 forms a 90° angle with the upper end face of the upper part of the first polarization beam splitter prism 102. The first polarization beam splitter film 1011 is parallel to the lower end face of the lower part of the first polarization beam splitter prism 102. The upper end face of the upper part and the lower end face of the lower part of the first polarization beam splitter prism 102 are both provided with high reflection films. The second polarization beam splitter film 1012 is parallel to the first polarization beam splitter film 1011. The first half-wave plate 103 is bonded to one end face of the first Faraday rotator crystal 106, and the second half-wave plate 104 is bonded to one end face of the second Faraday rotator crystal 105. The upper portion of the second polarization beam splitter prism 108 is bonded to the other end face of the first Faraday rotator crystal 106, and the lower portion of the second polarization beam splitter prism 108 is bonded to the other end face of the second Faraday rotator crystal 105. The third polarization beam splitter film 1013 forms a 45° angle with the upper end face of the upper portion of the second polarization beam splitter prism 108, the third polarization beam splitter film 1013 forms a 45° angle with the lower end face of the lower portion of the second polarization beam splitter prism 108, the fourth polarization beam splitter film 1014 is parallel to the third polarization beam splitter film 1013, the upper end face of the upper portion of the second polarization beam splitter prism 108 is provided with a high reflection film, and the lower end face of the lower portion of the second polarization beam splitter prism 108 is provided with a high transmittance film. The lower end face of the lower portion of the second polarization beam splitter prism 108 is bonded to the end face where the long bottom side of the turning prism 107 is located. The signal port Prot1 is located on the right end face of the upper part of the first polarization beam splitter prism 102, the signal port Prot2 is located on the left end face of the middle part of the first polarization beam splitter prism 102, the signal port Prot3 is located on the left end face of the rhombus prism 101, the signal port Prot4 is located on the right end face of the upper part of the second polarization beam splitter prism 108, and the signal port Port5 is located on the right end face of the middle part of the second polarization beam splitter prism 108.

[0038] The positions of the first half-wave plate 103 and the first Faraday rotatable crystal 106 can be interchanged, and the positions of the second half-wave plate 104 and the second Faraday rotatable crystal 105 can be interchanged.

[0039] All mating surfaces and signal port surfaces are provided with anti-reflection coating. The angle of signal light entering the circulator is 1~5°.

[0040] like Figure 2As shown, the signal light is incident from Port 1 to the upper portion of the first polarization beam splitter prism 102 that is not attached to the end face of the first half-wave plate 103. After passing through the first polarization beam splitter film 1011, the P light in the signal light is transmitted, and the S light is reflected. The P light is transmitted to the second polarization beam splitter film 1012 and then transmitted. The P light is then reflected by the lower end face of the lower portion of the first polarization beam splitter prism 102. The S light passes through the first half-wave plate 103 and the first Faraday rotator crystal 106. After the P light passes through the second half-wave plate 104 and the second Faraday rotator crystal 105, the original P light becomes S light, and the original S light is converted into The light is converted into P light, and the rotated S light is incident on the lower part of the second polarization beam splitter prism 108, and is reflected by the fourth polarization beam splitter film 1014. The rotated P light is incident on the upper part of the second polarization beam splitter prism 108, and is reflected by the upper end face of the upper part of the second polarization beam splitter prism 108, and is transmitted by the third polarization beam splitter film 1013, and is transmitted by the fourth polarization beam splitter film 1014. The two are combined and transmitted to the turning prism 107. The signal light is reflected twice by the turning prism 107 and is output from the end face where the long bottom side of the turning prism 107 is located to the second polarization beam splitter prism 108.

[0041] like Figure 3 As shown, after the signal light is transmitted to the fourth polarization beam splitter film 1014, the P light in the signal light is transmitted, the S light is reflected, the P light is transmitted by the third polarization beam splitter film 1013, the P light passes through the first Faraday rotator crystal 106 and the first half-wave plate 103, and the S light passes through the second Faraday rotator crystal 105 and the second half-wave plate 104, and the polarization directions of both remain unchanged. The P light enters the first polarization beam splitter prism 102, passes through the first polarization beam splitter film 1011, and is output from the left end face of the middle part of the first polarization beam splitter prism 102 to the signal port Port2; the S light is transmitted to the first polarization beam splitter prism 102, is reflected by the lower end face of the lower part of the first polarization beam splitter prism 102, is reflected by the second polarization beam splitter film 1012, is transmitted to the rhombus prism 101, and is then reflected by the upper and lower end faces of the rhombus prism 101 and is transmitted to the signal port Port3.

[0042] like Figure 4 and Figure 5As shown, the signal light enters the first polarization beam splitter prism 102 from the signal port Port2, and after passing through the first polarization beam splitter film 1011, the P light in the signal light is transmitted, and the S light is reflected. The S light is reflected by the second polarization beam splitter film 1012 and then incident into the second polarization beam splitter prism 108, and after being reflected by the third polarization beam splitter film 1013, and after being reflected by the fourth polarization beam splitter film 1014, it is transmitted to the signal port Port5. After the P light passes through the first half-wave plate 103 and the first Faraday rotator crystal 106, the original P light is converted into S light. The rotated S light is incident into the second polarization beam splitter prism 108, and after being reflected by the upper end face of the upper part of the second polarization beam splitter prism 108, and after being reflected by the third polarization beam splitter film 1013, it is transmitted to the signal port Port4.

[0043] like Figure 6 As shown, the signal light enters the turning prism 101 from the signal port Port3, is reflected by the upper and lower end surfaces of the turning prism 101, and then enters the first polarization beam splitter prism 102. After passing through the second polarization beam splitter film 1012, the P light in the signal light is transmitted, and the S light is reflected. After the S light is reflected by the lower end surface of the lower part of the first polarization beam splitter prism 102, the S light passes through the second half-wave plate 104 and the second Faraday rotator crystal 105, and the original S light is converted into P light. The rotated P light enters the second polarization beam splitter prism 108, is transmitted by the fourth polarization beam splitter film 1014, and is transmitted to the signal port Port5. After the P light enters the middle part of the second polarization beam splitter prism 108, it is transmitted by the third polarization beam splitter film 1013 and is transmitted to the signal port Port4.

[0044] Example 2: Figure 7 As shown, the optical circulator with multi-channel input and output functions of this embodiment includes an optical circulator core composed of an rhombus prism 201, a first polarization beam splitter prism 202 (the first polarization beam splitter prism 202 has a first polarization beam splitter film 2011 and a second polarization beam splitter film 2012), a first half-wave plate 203, a second half-wave plate 204, a first Faraday rotator crystal 206, a second Faraday rotator crystal 205 (the second polarization beam splitter prism 205 has a third polarization beam splitter film 2013 and a fourth polarization beam splitter film 2014), a turning prism 207, and a second polarization beam splitter prism 208, and five single-fiber collimators 210, 220, 230, 240 and 250.

[0045] Figure 7Schematic diagram of the optical path of the five-port optical circulator based on the single fiber collimator of this embodiment. The optical signal of the signal port Port1 is collimated by the collimator 210 and then enters the first polarization beam splitter prism 202 of the circulator core, and passes through the first half-wave plate 203, the second half-wave plate 204, the first Faraday rotator crystal 206, the second Faraday rotator crystal 205, and the second polarization beam splitter prism 208 in sequence before reaching the turning prism 207. After the optical path is turned back by the turning prism, it passes through the second polarization beam splitter prism 208, the first Faraday rotator crystal 206, the second Faraday rotator crystal 205, the first half-wave plate 203, and the second half-wave plate 204 in sequence, and then respectively exits through the first polarization beam splitter prism 202 and the rhombus prism 201, and then is coupled to the signal ports Port2 and Port3 through the single fiber collimators 220 and 230, respectively.

[0046] The optical signals of signal ports Port2 and Port3 are collimated by single fiber collimators 220 and 230 and then enter the first polarization beam splitter prism 202 of the optical circulator core. The signal light emitted from signal port Port2 is coupled to the single fiber collimator 240 through the optical circulator core component and transmitted to signal port Port4; the signal light emitted from signal port Port3 is coupled to the single fiber collimator 250 through the optical circulator core component and transmitted to signal port Port5.

[0047] Example 3: Figure 8 As shown, the optical circulator with multi-channel input and output functions of this embodiment includes an optical circulator core composed of an rhombus prism 301, a first polarization beam splitter prism 302 (the first polarization beam splitter prism 302 has a first polarization beam splitter film 3011 and a second polarization beam splitter film 3012 inside), a first half-wave plate 303, a second half-wave plate 304, a first Faraday rotator crystal 306, a second Faraday rotator crystal 305, a turning prism 307, a second polarization beam splitter prism 308 (the second polarization beam splitter prism 308 has a third polarization beam splitter film 3013 and a fourth polarization beam splitter film 3014 inside), and five dual-fiber collimators 310, 320, 330, 340 and 350.

[0048] Figure 8Schematic diagram of the optical path of the five-port optical circulator based on the single fiber collimator of the present embodiment. The optical signal of the signal port Port1 is collimated by the collimator 310 and then enters the first polarization beam splitter prism 302 of the circulator core, and passes through the first half-wave plate 303, the second half-wave plate 304, the first Faraday rotator crystal 306, the second Faraday rotator crystal 305, and the second polarization beam splitter prism 308 in sequence to reach the turning prism 307. After the optical path is turned back by the turning prism, it passes through the second polarization beam splitter prism 308, the first Faraday rotator crystal 306, the second Faraday rotator crystal 305, the first half-wave plate 303, and the second half-wave plate 304 in sequence, and then respectively exits through the first polarization beam splitter prism 302 and the rhombus prism 301, and then is coupled to the signal ports Port2 and Port3 through the dual-fiber collimators 320 and 330, respectively.

[0049] The optical signals of signal ports Port2 and Port3 are collimated by dual-fiber collimators 320 and 330 and then enter the first polarization beam splitter prism 302 of the optical circulator core. The signal light emitted from signal port Port2 is coupled to the dual-fiber collimator 340 through the optical circulator core component and transmitted to signal port Port4; the signal light emitted from signal port Port3 is coupled to the dual-fiber collimator 350 through the optical circulator core component and transmitted to signal port Port5.

[0050] Example 4: Fig. 9 As shown, the optical circulator with multi-channel input and output functions of this embodiment includes a multi-channel optical circulator core 460, three single-fiber collimators 410, 440 and 450, and two optical port components 420 and 430. Fig. 9 Schematic diagram of the miniaturized five-port optical circulator based on optical port of this embodiment. The specific optical path transmission direction of this embodiment is consistent with that of embodiment 2, except that the single fiber collimators 220 and 230 used for optical signal coupling of signal ports Port2 and Port3 in embodiment 2 are replaced by optical port components 420 and 430. The above describes the specific implementation of the utility model, but those skilled in the art should understand that this is only an example, and those skilled in the art can make various changes or modifications to this implementation without departing from the principle and essence of the utility model, but these changes and modifications fall within the protection scope of the utility model.

Claims

1. A low-cost multi-port optical circulator, characterized in that: It includes an oblique square prism, a first polarization beam splitter prism, a first half-wave plate, a second half-wave plate, a first Faraday rotator crystal, a second Faraday rotator crystal, a second polarization beam splitter prism and a turning prism; The cross section of the rhombus prism is a parallelogram structure, which is used to change the transmission direction of the signal light; The cross section of the first polarization beam splitter prism is an isosceles trapezoidal structure, and a first polarization beam splitter film and a second polarization beam splitter film are arranged inside the first polarization beam splitter prism, which is divided into three parts: upper, middle and lower parts; The cross section of the second polarization beam splitter prism is a right-angled trapezoidal structure with a base angle of 45°, and a third polarization beam splitter film and a fourth polarization beam splitter film are arranged inside the second polarization beam splitter prism, which is divided into three parts: upper, middle and lower parts; The cross section of the turning prism is an isosceles right triangle structure, which is used to reflect the signal light and make a 180° turn in the transmission direction of the signal light; The first polarization beam splitter prism and the second polarization beam splitter prism are used to input or output signal light, and the first polarization beam splitter film, the second polarization beam splitter film, the third polarization beam splitter film and the fourth polarization beam splitter film are used to separate or synthesize P-polarized light and S-polarized light in the signal light; the first half-wave plate and the first Faraday rotator crystal are bonded together, and the second half-wave plate and the second Faraday rotator crystal are bonded together, and are both used to perform 90° polarization rotation on the signal light in a single transmission direction, and not perform polarization rotation on the signal light in another transmission direction; The right end faces of the upper and lower parts of the cross section of the first polarization beam splitter prism are respectively bonded to one end face of the first half-wave plate and the second half-wave plate, the first polarization beam splitter film forms an angle of 90° with the upper end face of the upper part of the first polarization beam splitter prism, the first polarization beam splitter film is parallel to the lower end face of the lower part of the first polarization beam splitter prism, the upper end face of the upper part and the lower end face of the lower part of the first polarization beam splitter prism are both provided with high reflection films, the second polarization beam splitter film is parallel to the first polarization beam splitter film, the first half-wave plate is bonded to one end face of the first Faraday rotator crystal, the second half-wave plate is bonded to one end face of the second Faraday rotator crystal, the upper part of the second polarization beam splitter prism is bonded to the other end face of the first Faraday rotator crystal, and the lower part of the second polarization beam splitter prism is bonded to the other end face of the second Faraday rotator crystal; the third polarization beam splitter film is bonded to the second polarization beam splitter prism The upper end face of the upper part of the beam splitter prism forms an angle of 45°, the third polarization beam splitting film and the lower end face of the lower part of the second polarization beam splitter prism form an angle of 45°, the fourth polarization beam splitting film is parallel to the third polarization beam splitting film, the upper end face of the upper part of the second polarization beam splitter prism is provided with a high reflection film, and the lower end face of the lower part of the second polarization beam splitter prism is provided with a high transmittance film; the lower end face of the lower part of the second polarization beam splitter prism is in contact with the end face where the long bottom edge of the turning prism is located; the signal port Prot1 is located on the right end face of the upper part of the first polarization beam splitter prism, the signal port Prot2 is located on the left end face of the middle part of the first polarization beam splitter prism, the signal port Prot3 is located on the left end face of the rhombus prism, the signal port Prot4 is located on the right end face of the upper part of the second polarization beam splitter prism, and the signal port Port5 is located on the right end face of the middle part of the second polarization beam splitter prism.

2. A low-cost multi-port optical circulator according to claim 1, characterized in that: The positions of the first half-wave plate and the first Faraday rotator crystal can be interchanged, and the positions of the second half-wave plate and the second Faraday rotator crystal can be interchanged.

3. A low-cost multi-port optical circulator according to claim 1, characterized in that: All mating surfaces and signal port faces are anti-reflection coated.

4. A low-cost multi-port optical circulator according to claim 1, characterized in that: The angle at which the signal light enters the optical circulator is 1~5°.

Images