CN215264115U - Reflective optical circulator - Google Patents

Abstract

The embodiment of the utility model discloses reflection type optical circulator, include: the optical fiber collimator is used for emitting a first light beam; the optical fiber collimator comprises a plurality of optical waveguide chips or a plurality of optical fiber pins; the optical fiber collimator at least comprises a first output end, a second output/input end and a third output/input end; the central axis directions of the first output end, the second output/input end and the third output/input end are mutually parallel and are in a first plane; the light combining and splitting crystal, the polarization conversion component, the light beam deflection component, the first Faraday rotation sheet and the reflective lens are sequentially positioned on the first light beam propagation path; the light beam incident to the reflective lens is parallel to the light beam emergent after being reflected by the reflective lens; the first light beam output by the first output end is received by the second output/input end; the first light beam output from the second output/input terminal is received by the third output/input terminal. The utility model provides a reflection type optical circulator is small, simple process, cost are lower.

Description

Reflective optical circulator

Technical Field

The embodiment of the utility model provides a relate to the optical communication field, especially relate to a reflection type optical circulator.

Background

In an optical fiber communication system, the transmission of reverse light brings instability to devices and the system, an optical circulator is a non-reciprocal device with multi-port input and output, optical signals can only carry out loop transmission along a fixed path, and therefore the separation of forward and reverse transmission light is achieved, and the optical circulator is widely applied to optical communication subsystems such as a single-fiber bidirectional transmission system, a dispersion compensation unit, a wavelength blocker, a channel equalizer, a wavelength selective switch and the like.

The explosion of internet applications has promoted the large-scale construction of data centers, and high-speed data transmission between data center servers can only be realized through optical fiber interconnection technology. The optical fiber interconnection technology goes through multimode fiber parallel transmission, single-mode fiber parallel transmission and single-mode fiber wavelength division multiplexing transmission stages, wherein the wavelength division multiplexing transmission adopts four working wavelengths of 1270, 1290, 1310 and 1330 nm. In order to further save optical fiber resources, data center users put forward the requirement of wavelength division multiplexing single-fiber bidirectional transmission, and the separation of receiving and transmitting optical signals is realized through an optical circulator.

In a conventional three-port optical circulator, input/output ports thereof are located at two sides and cannot be conveniently integrated into an optical fiber transceiver module of a data center, and generally, three independent single optical fiber collimators or a three-channel optical fiber collimator array are adopted for the input/output ports, so that the port spacing is large, the sizes of other elements in the optical circulator are required to be correspondingly increased, the miniaturization design of the optical circulator is not facilitated, and the optical circulator is difficult to integrate into the optical fiber transceiver module with a compact structure.

SUMMERY OF THE UTILITY MODEL

In view of this, the embodiment of the present invention provides a reflective optical circulator, which has the advantages of small structural size, simple manufacturing process, and low cost, and meets the requirement of the wavelength division multiplexing single-fiber bidirectional transmission module in the data center.

In a first aspect, an embodiment of the present invention provides a reflective optical circulator, including:

the optical fiber collimator is used for emitting a first light beam; the optical fiber collimator comprises a plurality of optical waveguide chips or a plurality of optical fiber pins;

the optical fiber collimator at least comprises a first output end, a second output/input end and a third output/input end; wherein the central axis directions of the first output end, the second output/input end and the third output/input end are parallel to each other and in a first plane;

the polarization beam splitter prism, the polarization conversion assembly, the light beam deflection assembly, the first Faraday rotation sheet and the reflective lens are sequentially positioned on the first light beam propagation path; the light beam incident to the reflective lens is parallel to the light beam emitted after being reflected by the reflective lens;

the first light beam output by the first output terminal is received by the second output/input terminal; the first light beam output by the second output/input terminal is received by the third output/input terminal.

Optionally, the polarization splitting prism includes an oblique prism and a right-angle prism;

the rhombic prism and the right-angle prism are arranged in a gluing mode; the gluing surface is plated with a polarization beam splitting film.

Optionally, the optical fiber collimator further includes a collimating lens;

the collimating lens is used for collimating the first light beam.

Optionally, the beam deflection assembly comprises a wollaston prism;

the Wollaston prism comprises two prisms which are adjacent to each other, and the optical axes of the two prisms are vertical to each other.

Optionally, the polarization conversion assembly includes a glass plate, a half-wave plate, and a second faraday rotation plate;

the glass sheet is positioned on the propagation path of the second light beam emitted by the polarization beam splitter prism;

the half-wave plate is positioned on a propagation path of the third light beam emitted by the polarization beam splitter prism; the third light beam is perpendicular to the direction of propagation of the second light beam;

and the second Faraday optical rotation plate is positioned on the propagation paths of the second light beam after passing through the glass plate and the third light beam after passing through the half-wave plate.

Optionally, the included angle between the fast axis direction of the half-wave plate and the first plane is 45 °.

Optionally, the reflective lens includes a convex spherical surface and a plane, and the plane is located on a back focal plane of the convex spherical surface.

The utility model provides a reflection type optical circulator, include: the optical fiber collimator is used for emitting a first light beam; the optical fiber collimator comprises a plurality of optical waveguide chips or a plurality of optical fiber contact pins, the volume of an incident beam is further reduced, and the optical fiber collimator at least comprises a first output end, a second output/input end and a third output/input end; the central axis directions of the first output end, the second output/input end and the third output/input end are mutually parallel and are in a first plane; furthermore, by reasonably arranging each optical assembly, the first light beam sequentially passes through the polarization beam splitter prism, the polarization conversion assembly, the light beam deflection assembly, the first Faraday optical rotation sheet and the reflective lens, and meanwhile, the reflective lens ensures that the light beam incident to the reflective lens is parallel to the light beam emitted after being reflected by the reflective lens, and the first light beam output by the first output end is ensured to be received by the second output/input end; the first light beam output by the second output/input terminal is received by the third output/input terminal. The reflective optical circulator arranged in the technical scheme has the advantages of small structure size, simple preparation process and low cost, and meets the requirements of the wavelength division multiplexing single-fiber bidirectional transmission module in the data center.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments made with reference to the following drawings:

fig. 1 is a schematic structural diagram of a reflective optical circulator according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an optical waveguide chip according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a three-fiber collimator according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a structure and an optical path of a PBS prism provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of the structure and optical path of a conventional displacement crystal;

fig. 6 is a schematic diagram of an optical path in a wollaston prism according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a polarization conversion module according to an embodiment of the present invention;

fig. 8 is a schematic diagram of an optical path in a reflective lens provided in an embodiment of the present invention;

fig. 9 is a schematic diagram of an optical path of a reflective optical circulator provided by an embodiment of the present invention;

fig. 10 is a schematic diagram illustrating polarization direction changes of devices in a reflective optical circulator according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail through the following embodiments with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, not all embodiments, and all other embodiments obtained by those skilled in the art without creative efforts based on the embodiments of the present invention all fall into the protection scope of the present invention.

Examples

An embodiment of the present invention provides a reflective optical circulator. Fig. 1 is a schematic structural diagram of a reflective optical circulator according to an embodiment of the present invention; fig. 2 is a schematic structural diagram of an optical waveguide chip according to an embodiment of the present invention; fig. 3 is a schematic structural diagram of a three-fiber collimator according to an embodiment of the present invention.

As shown in fig. 1 and 2, the reflective optical circulator includes:

a fiber collimator 1 for emitting a first light beam; the optical fiber collimator 1 comprises a plurality of optical waveguide chips 10a or a plurality of optical fiber pins 10 a';

the optical fiber collimator 1 at least comprises a first output end (I), a second output/input end (II) and a third output/input end (III); the central axis directions of the first output end (I), the second output/input end (II) and the third output/input end (III) are mutually parallel and are in a first plane;

the polarization beam splitter prism 2, the polarization conversion component 3, the light beam deflection component 4, the first Faraday rotation sheet 5 and the reflective lens 6 are sequentially positioned on the first light beam propagation path; the light beam incident to the reflective lens 6 is parallel to the light beam emitted after being reflected by the reflective lens 6;

the first light beam output by the first output end is received by the second output/input end; the first light beam output by the second output/input end is received by the third output/input end.

Illustratively, as shown in fig. 1-3, the reflective optical circulator is configured to include a fiber collimator 1, and emit a first light beam, wherein the first light beam includes a laser beam with good monochromaticity. In order to further reduce the overall volume of the reflective optical circulator, the optical fiber collimator 1 is configured to include a plurality of optical waveguide chips 10a (as shown in fig. 2) or a plurality of optical fiber pins 10 a' (as shown in fig. 3) for outputting the first light beam. Along the propagation direction of the first light beam, the optical waveguide chip 10a is composed of three optical waveguides parallel to each other and close to each other, and the three optical waveguides function like three pigtails in a three-fiber stub 10 a' to emit light beams.

Furthermore, the optical fiber collimator 1 at least comprises a first output end (I), a second output/input end (II) and a third output/input end (III), wherein the central axis directions of the first output end (I), the second output/input end (II) and the third output/input end (III) are mutually parallel and are in a first plane, and according to the requirement of practical application, the first light beam is output from any one port of the first output end (I), the second output/input end (II) and the third output/input end (III). Specifically, a Polarization Beam Splitter (PBS) prism 2 is arranged on a propagation path of a first light Beam on one side of the optical fiber collimator 1, and compared with a common conventional displacement crystal, the birefringence coefficient of the PBS prism is larger, when the angle of an inclined plane coated with a PBS film in the prism is 45 degrees, the splitting ratio d/L can reach 1, and the splitting effect is good. When the first light beam is incident on the polarization beam splitter prism 2, the first light beam is split into two linearly polarized light beams with polarization directions perpendicular to each other, such as: p-polarized light and S-polarized light. The polarization conversion component 3 is arranged on one side of the polarization beam splitter prism 2, which is far away from the optical fiber collimator 1, when a first light beam emitted from the first output end is sequentially split into two light beams with mutually vertical polarization directions through the polarization beam splitter prism 2, the two light beams are changed into two linearly polarized light beams with consistent polarization directions after passing through the polarization conversion component 3, the two light beams with consistent polarization directions pass through the light beam deflection component 4, the propagation directions of the light beams are transversely displaced and deflected and then reach the first Faraday optical rotation sheet 5, the polarization directions of the two light beams enter the reflective lens 6 after being rotated through the first Faraday optical rotation sheet 5, the light beams incident to the reflective lens 6 are parallel to the light beams emitted after being reflected by the reflective lens 6 through the reasonable arrangement of the reflective lens 6, and therefore the reflective receiving is realized. The light beam reflected by the reflective lens 6 passes through the first Faraday rotation plate 5, the light beam deflection component 4, the polarization conversion component 3 and the polarization beam splitter prism 2 in sequence, and the light beam passes through the light beam deflection component 4 twice, so that the propagation direction of the light beam is deviated, and the light beam is combined by the polarization beam splitter prism 2 and then is received by the second output/input end. The circulator designed by the structure has simple structure and low cost, can further reduce the volume of the circulator and meet the requirement of a wavelength division multiplexing single-fiber bidirectional transmission module in a data center. Similarly, when the first light beam is reflected from the second output/input end and received by the third output/input end, which is not described here, a circulator with one-side input and output is realized.

To sum up, the embodiment of the present invention provides a reflective optical circulator, which emits a first light beam by setting an optical fiber collimator, where the optical fiber collimator includes a plurality of optical waveguide chips or a plurality of optical fiber pins, so as to further reduce the volume of an incident light beam, and the optical fiber collimator at least includes a first output end, a second output/input end, and a third output/input end; the central axis directions of the first output end, the second output/input end and the third output/input end are mutually parallel and are in a first plane; furthermore, by reasonably arranging each optical assembly, the first light beam is reflected by the reflective lens after sequentially passing through the polarization beam splitter prism, the polarization conversion assembly, the light beam deflection assembly and the first Faraday optical rotation sheet, and meanwhile, the reflective lens ensures that the light beam incident to the reflective lens is parallel to the light beam emitted after being reflected by the reflective lens, and the first light beam output by the first output end is ensured to be received by the second output/input end; the first light beam output by the second output/input terminal is received by the third output/input terminal. The reflective optical circulator arranged in the technical scheme has the advantages of small structure size, simple preparation process and low cost, and meets the requirements of the wavelength division multiplexing single-fiber bidirectional transmission module in the data center.

To further adjust the transmission of the first light beam, optionally, the fiber collimator 1 further includes a collimating lens 10 b; the collimating lens 10b is used for collimating the output first light beam.

Illustratively, as a possible embodiment, the fiber collimator 1 includes a plurality of fiber stub 10 a' and a collimating lens 10b (as shown in fig. 3), or the fiber collimator 1 includes a plurality of optical waveguide chips 10a and a collimating lens 10b (as shown in fig. 2). The collimating lens 10b is used for collimating and outputting the first light beam, and the optical fiber stub 10 a' and the optical waveguide chip 10a have the advantages of compact structure, stable light beam transmission and the like. Preferably, the optical fiber collimator 1 includes three optical waveguide chips 10a and a collimating lens 10b, an end face of the optical waveguide chip 10a is disposed on a front focal plane of the collimating lens, the collimating lens 10b converts the small-spot large-divergence-angle light beam emitted by the optical waveguide into a large-spot small-divergence-angle light beam, and the large-spot small-divergence-angle light beam intersects with a back focal point of the collimating lens 10b to complete collimation of the light beam and output a first light beam. The distance between the three optical waveguides and the focal length of the collimating lens 10b are properly designed, so that the included angle between the three collimated beams is matched with the deflection angle of the beam deflection component 4, and the input and output coupling of optical signals is realized. The optical waveguide chip can simultaneously realize other functions such as multiplexing/demultiplexing of a plurality of optical wavelengths, in addition to providing three optical waveguides which are close to each other and parallel to each other as input/output ports. The optical circulator with the structure can realize the hybrid integration of an integrated optical device (based on an optical waveguide) and a micro-optical device (based on a prism, a lens, a wave plate, a crystal and the like).

As shown in fig. 2, the three optical waveguides on the optical waveguide chip 10a are respectively used as input/output ports (i-c) of the optical circulator, and light beams can enter the circulator from these ports or can exit from these ports. For example, when the middle optical waveguide is located on the axis of the collimating lens 10b, the collimated light beams are transmitted along the axis, the other two optical waveguides are transversely off-axis, the light beams output by the two optical waveguides are collimated and form an included angle with the axis of the collimating lens 10b, preferably, the included angles between the light beams output by the two optical waveguides and the axis of the collimating lens 10b are the same, and three collimated light beams can intersect at a back focus F1 of the collimating lens 10b through the structural arrangement; further, the focal length of the collimating lens 10b is properly designed, so that the included angle between the three collimated light beams matches with the deflection angle of the light beam deflection assembly 4, thereby realizing input and output coupling of optical signals.

On the basis of the above embodiments, fig. 4 is a schematic diagram of the structure and the optical path of the PBS prism provided by the embodiment of the present invention; fig. 5 is a schematic diagram of the structure and optical path of a conventional displacement crystal. As shown in fig. 4, the polarization splitting prism 2 may alternatively include a rhombic prism 21 and a rectangular prism 22; the rhombic prism 21 and the right-angle prism 22 are arranged in a gluing mode; the bonded surface is plated with a polarization beam splitting film 23.

Illustratively, the PBS prism 2 includes an oblique prism 21 and a right-angle prism 22 bonded together, and the bonded surfaces of the two are coated with a Polarizing Beam Splitter (PBS) film 22, see fig. 4 (a). S light with polarization direction perpendicular to the optical meridian plane will be reflected by the PBS film layer 22, while p light with polarization direction parallel to the optical meridian plane can be transmitted from the PBS film layer 22, and the s light and the p light can travel in the PBS prism 2, see fig. 4(b) and fig. 4(c), respectively.

After a beam of natural light or arbitrarily polarized light passes through the PBS prism 2, the p-light component is output from the transmission optical path, and the s-light component is output from the reflection optical path, so as to obtain two linearly polarized lights with mutually perpendicular polarization directions and mutually parallel propagation directions, which is a polarization splitting process, as shown in fig. 4 (d). On the contrary, if two linearly polarized lights with mutually perpendicular polarization directions and mutually parallel propagation directions are input from opposite directions, a randomly polarized light is synthesized, which is a polarization light combination process.

It can be seen that the PBS prism can separate two mutually perpendicular polarized lights over a large distance in the transverse direction (perpendicular to the propagation direction of the optical path) within a short longitudinal (propagation direction of the optical path) thickness. In the conventional polarization splitting method using a shift crystal, as shown in fig. 5, even if a crystal with a high birefringence coefficient is used, the splitting ratio d/L (the ratio of the transverse splitting distance d to the longitudinal crystal thickness L) is still limited, and the splitting ratio d/L of the PBS prism 2 can reach 1. In the above embodiment, it is mentioned that the three collimated light beams output by the three fiber collimators 1 are intersected at the back focal point F of the collimating lens 10b, and the focal point is directed to the center of the middle inclined plane of the light beam conversion assembly 4 in the light beam propagation direction, that is, the optical thicknesses of the light combining and splitting element and the polarization conversion assembly 3 are smaller than the focal length of the collimating lens, so as to be placed in the focal point. The conventional shift crystal needs a thicker crystal to completely separate the two polarized light beams due to too small splitting ratio, and thus cannot be placed in the focus of the collimating lens 10b, so the PBS prism used in this embodiment can meet this requirement.

On the basis of the above embodiment, the back focus F of the collimating lens 10b points to the center of the middle inclined plane of the light beam conversion component 4, fig. 6 is a schematic diagram of the light path in the wollaston prism provided by the embodiment of the present invention, as shown in fig. 6, optionally, the light beam conversion component 4 includes a wollaston prism; the Wollaston prism comprises two prisms which are adjacent to each other, and the optical axes of the two prisms are vertical to each other. As shown in FIG. 6, when the + 45-degree polarized light beam which is incident normally at an inclination angle of +2 phi from the horizontal direction passes through the wedge plate 41 and the wedge plate 42 and then exits at an inclination angle of + phi when the + 45-degree polarized light beam is selected for use, and then enters the wedge plate 42 and the wedge plate 41 again after being reflected by the reflective lens, the-45-degree polarized light beam which is incident reversely at an inclination angle of-phi is satisfied, and the light beam exits in the horizontal direction, and at this time, the light beam which passes through the Wollaston prism for the second time is deflected by an angle phi clockwise compared with the light beam which reaches the Wollaston prism for the first time. Similarly, the first light beam output by the second output/input end passes through the Wollaston prism again, and then the light beam deflects clockwise by an angle phi.

On the basis of the above embodiment, a polarization conversion module 3 is disposed on one side of the PBS prism 2 away from the three optical fiber collimators 1, and fig. 7 is a schematic structural diagram of a polarization conversion module provided by an embodiment of the present invention. As shown in fig. 7, in which fig. 7b is a side view along direction a in fig. 7a, in the present embodiment, optionally, the polarization conversion assembly 3 includes a glass plate 31, a half-wave plate 32, and a second faraday rotator 33; the glass plate 31 is positioned on the propagation path of the second light beam exiting through the PBS prism 2; the half-wave plate 32 is positioned on the propagation path of the third light beam emitted by the PBS prism 2, and the propagation direction of the third light beam is vertical to that of the second light beam; the second faraday rotator 33 is located on the propagation path of the second light beam after passing through the glass plate 31 and the third light beam after passing through the half-wave plate 32.

Illustratively, as shown in fig. 7a, the glass plate 31 and the half-wave plate 32 are disposed above and below and side by side on two different light paths split by the PBS prism 2, and the second light beam and the third light beam split by the PBS prism 2 enter the glass plate 31 and the half-wave plate 32, respectively. Alternatively, as shown in fig. 7b, the fast axis direction of the half-wave plate is at an angle of 45 ° to the first plane. The first plane is a plane in which the central axis directions of the first output end (first), the second output/input end (second) and the third output/input end (third) are parallel to each other, and can also be understood as a horizontal plane. As shown in fig. 7b, the fast axis of the half-wave plate 32 forms an angle of 45 ° with the horizontal direction, and after linearly polarized light with the polarization direction in the horizontal (or vertical) direction passes through the half-wave plate 32, the polarization direction of the light beam is rotated by 90 ° to become linearly polarized light in the vertical (or horizontal) direction, so that the light beam is decomposed into a second light beam and a third light beam with mutually perpendicular polarization directions by the PBS prism 2, and after passing through the glass plate 31 and the half-wave plate 32, the polarization directions of the second light beam and the third light beam become consistent.

The present embodiment employs a reflective lens that has less influence on the propagation direction of light for the purpose of single-sided input/output of an incident beam. Fig. 8 is a schematic diagram of an optical path in a reflective lens provided in an embodiment of the present invention;

fig. 9 is a schematic optical path diagram of a reflective optical circulator according to an embodiment of the present invention. As shown in fig. 8 and 9, the reflective lens 6 may alternatively include a convex spherical surface and a flat surface, the flat surface is located on the back focal plane of the convex spherical surface, and on the basis of the above embodiment, the convex spherical surface faces the first faraday rotation plate 5, and the front focal point of the convex spherical surface is aligned with the central point Q of the inclined plane in the wollaston prism. Illustratively, the reflective lens 6 is a plano-convex lens, which includes a convex spherical surface and a flat surface, wherein the convex spherical surface generates refraction and focusing effects, the flat surface is located on the back focal plane of the convex spherical surface, and the flat surface is coated with a high reflective film. As shown in fig. 8, by using the reflective lens, when the light beam enters from the convex spherical surface, after being transmitted through the reflective lens 6 and reflected by the plane, the outgoing light beam is always parallel to the incident light beam, which is independent of the incident angle, thereby reducing the difficulty of adjusting the light path, improving the assembly efficiency of the device, reducing the light beam loss, controlling the propagation direction of the light beam, effectively simplifying the design of the device structure in the annular cavity, and reducing the production cost.

Based on the inventive concept provided by the above embodiments, a possible embodiment will be described below. The propagation path and the polarization direction change of the light beam in a reflective optical circulator are described with reference to fig. 1-10. As shown in fig. 9, the light beam incident from the first output port r enters the PBS prism 2, and then forms two light beams L1 and L2 having mutually perpendicular polarization directions, and the positions and polarization directions of the two light beams in the cross section are shown in fig. 10 (b). As can be seen from fig. 9, in a side view, the light beam L0 enters the displacement crystal and is split into two light beams L1 and L2, and the optical paths of the two light beams L1 and L2 are separated.

The light beams L1, L2 pass through the glass plate 31 and the half-wave plate 32 respectively, see the arrangement of the glass plate 31 and the half-wave plate 32 in fig. 7, and the fast axis direction of the half-wave plate 32, the polarization direction of the light beam L1 is unchanged, and the polarization direction of the light beam L2 will be deflected by 90 °. Thus, after the two light beams pass through the glass plate 31 and the half-wave plate 32, the polarization directions of the light beam L1 and the light beam L2 are the same, as shown in fig. 10 (c).

Then, the light beams L1 and L2 enter the second faraday rotator 33, and the polarization direction is rotated clockwise by 45 °, as shown in fig. 10 (d). At this time, the polarization direction of the light beam L1 is the same as that of the light beam L2.

Then, the light beams L1 and L2 are incident on the wollaston prism 4, respectively, and the optical paths in the wollaston prism 4 are shown in fig. 6. In the top view, the light beams L1 and L2 are linearly polarized light of +45 °, and are overlapped with each other, and enter at an inclination angle of +2 °, after passing through the wollaston prism 4, the polarization direction does not change, and the transmission direction is deflected clockwise by an angle of + and exits at an inclination angle of + phi. After passing through the wollaston prism 4, the transverse positions and polarization directions of the light beams L1 and L2 are shown in fig. 10 (e).

After passing through the wollaston prism 4, the light beams L1 and L2 enter the first faraday rotation 5 plate, and the polarization direction of the light beams L1 and L2 rotates clockwise by 45 ° because the first faraday rotation 5 rotates the polarization direction of the light beams, and as shown in fig. 10(f), the polarization directions of the light beams L1 and L2 are still parallel to each other.

The light beams emitted from the first faraday rotator 5 enter the reflective lens 6, and the side view shows that the light beams L1 and L2 parallel to each other are inverted after being reflected according to the property of the reflective lens shown in fig. 8; the top view shows that the two incident beams coincide with each other and that the two reflected beams also coincide with the incident beams.

The reflected light beams L1, L2 are reversely incident on the first faraday rotator 5 for the second time, and the polarization directions of the light beams L1, L2 are rotated by 45 ° clockwise by the rotation of the polarization direction of the light beams by the first faraday rotator 5, as shown in fig. 10 (g).

And then, the light beams L1 and L2 reversely enter the Wollaston prism 4 for the second time, at the moment, the two light beams are linearly polarized light with an angle of-45 degrees, the inclination angle of the incident light beam is-phi, the propagation direction of the light beam deflects again, the clockwise deflection angle phi is realized, and the light beam is emitted along the horizontal direction. I.e. the direction of propagation of the light beam makes an angle of 2 phi with the direction in which the light beam first strikes the wollaston prism 4 and the direction of propagation is towards the PBS prism. The positions and polarization directions of the light beams L1, L2 in the cross section at this time are shown in fig. 10 (h).

Thereafter, the light beams L1 and L2 are incident on the second faraday rotator 32 in the reverse direction for the second time, the polarization directions of the light beams L1 and L2 are rotated clockwise by 45 ° again, and as shown in fig. 10(i), the polarization direction of the reflected light beam is restored to the state before the forward light beam is incident on the second faraday rotator 32 for the first time, and the polarization directions of the two light beams L1 and L2 are still parallel to each other.

Then, the light beams L1 and L2 are incident on the half-wave plate 32 and the glass plate 31 in the reverse direction for the second time, and since the light beams L1 and L2 are reversed when passing through the reflective lens 6, the light beam L1 is incident on the half-wave plate 32, and the light beam L2 is incident on the glass plate 31, which is opposite to the case of the first normal incidence. After passing the half-wave plate 32 and the glass plate 31 for the second time, the light beam L1 is deflected 90 ° counterclockwise, while the polarization direction of the light beam L2 is unchanged. At this time, the polarization directions of the light beams L1, L2 are as shown in fig. 10(j), and the polarization directions of the light beams L1, L2 are perpendicular to each other.

When the light beams L1, L2 pass through the PBS prism 2 in the opposite direction for the second time, the two light beams L1, L2 with mutually perpendicular polarization directions are recombined to form a light beam L0, the polarization direction of which is shown in fig. 10(k), and finally the light beam L0 exits from the second output/input end of the fiber collimator.

Further, the first light beam incident from the second output/input end is emitted from the third output/input end of the optical fiber collimator 1, specifically, as shown in fig. 9, the light beam incident from the second output/input end is incident on the PBS prism 2 to form two light beams L1 and L2 with mutually perpendicular polarization directions, and the positions and polarization directions of the two light beams in the cross section are shown in fig. 10 (m). As can be seen from fig. 9, in a side view, the light beam L0 enters the PBS prism 2 and is split into two light beams L1 and L2, and the optical paths of the two light beams L1 and L2 are separated.

The light beams L1, L2 pass through the glass plate 31 and the half-wave plate 32 respectively, see the arrangement of the glass plate 31 and the half-wave plate 32 in fig. 7, and the fast axis direction of the half-wave plate 32, the polarization direction of the light beam L1 is unchanged, and the polarization direction of the light beam L2 will be deflected by 90 °. Thus, after the two light beams pass through the glass plate 31 and the half-wave plate 32, the polarization directions of the light beam L1 and the light beam L2 are the same, as shown in fig. 10 (n).

Then, the light beams L1 and L2 enter the second faraday rotator 33, respectively, and the polarization direction is rotated clockwise by 45 °, as shown in fig. 10 (o). At this time, the polarization direction of the light beam L1 is the same as that of the light beam L2.

Then, the light beams L1 and L2 are incident on the wollaston prism 4, respectively, and the optical paths in the wollaston prism 4 are shown in fig. 6. In the top view, the light beams L1 and L2 are both linearly polarized light of +45 °, and are overlapped with each other, and enter in the horizontal direction, after passing through the wollaston prism 4, the polarization direction does not change, and the transmission direction is deflected clockwise by an angle of phi and exits at an inclination angle of-phi. After passing through the wollaston prism 4, the transverse positions and polarization directions of the light beams L1 and L2 are shown in fig. 10 (p).

After passing through the wollaston prism 4, the light beams L1 and L2 enter the first faraday rotation 5 plate, and the polarization direction of the light beams L1 and L2 rotates clockwise by 45 ° because the first faraday rotation 5 plate rotates the polarization direction of the light beams, as shown in fig. 10(q), the polarization directions of the light beams L1 and L2 are still parallel to each other.

The light flux emitted from the first faraday rotator 5 enters the reflective lens 6, and as shown in fig. 8, the light fluxes L1, L2 parallel to each other are inverted after being reflected, as viewed in a side view, according to the characteristics of the reflective lens 6; viewed in plan, the two incident beams coincide with each other, and the two reflected beams also coincide with the incident beams.

The reflected light beams L1, L2 are reversely incident on the first faraday rotator 5 for the second time, and the polarization directions of the light beams L1, L2 are rotated by 45 ° clockwise by the rotation action of the first faraday rotator 5 on the polarization direction of the light beams, as shown in fig. 10 (r).

And then, the light beams L1 and L2 reversely enter the Wollaston prism 4 for the second time, at the moment, the two light beams are linearly polarized light with an angle of-45 degrees, the inclination angle of the incident light beam is + phi, the propagation direction of the light beams deflects again, the clockwise deflection angle phi is realized, and the light beams are emitted at an inclination angle of +2 phi. I.e. the direction of propagation of the light beam makes an angle of 2 phi with the direction in which the light beam first strikes the wollaston prism 4 and the direction of propagation is towards the PBS prism. The positions and polarization directions of the light beams L1, L2 in the cross section at this time are shown in fig. 10(s).

Thereafter, the light beams L1 and L2 are incident on the second faraday rotator 33 in the reverse direction for the second time, the polarization directions of the light beams L1 and L2 are rotated clockwise by 45 ° again, and the polarization directions of the reflected light beams are restored to the state before the forward light beams are incident on the second faraday rotator 33 for the first time, as shown in fig. 10(t), and the polarization directions of the two light beams L1 and L2 are still parallel to each other.

Then, the light beams L1 and L2 are incident on the half-wave plate 32 and the glass plate 31 in the reverse direction for the second time, and since the light beams L1 and L2 are reversed when passing through the reflective lens 6, the light beam L1 is incident on the half-wave plate 32, and the light beam L2 is incident on the glass plate 31, which is opposite to the case of the first normal incidence. After passing the half-wave plate 32 and the glass plate 31 for the second time, the light beam L1 is deflected 90 ° counterclockwise, while the polarization direction of the light beam L2 is unchanged. At this time, the polarization directions of the light beams L1, L2 are as shown in fig. 10(u), and the polarization directions of the light beams L1, L2 are perpendicular to each other.

When the light beams L1 and L2 pass through the PBS prism 2 in the opposite direction for the second time, the two light beams L1 and L2 with mutually perpendicular polarization directions are recombined to form a light beam L0, the polarization direction of which is shown in fig. 10(v), and finally the light beam L0 exits from the third output/input end of the optical fiber array.

Therefore, an incident light beam L0 is incident from a first output end (first) of the three optical fiber collimators, and is emitted from a second output/input end (second) after a series of changes such as light splitting, polarization direction rotation, propagation direction deflection, reflection, light combination and the like; similarly, the light beam incident from the second output/input end (c) also undergoes the same change as the light beam L0, and exits from the third output/input end (c). And because the polarization direction can only deflect towards one direction when the light beam passes through the Faraday rotator, the transmission direction can only deflect towards one direction when the light beam passes through the Wollaston prism, and the light path is irreversible, namely the light beam from the second output/input end cannot be emitted from the first output end and can only be emitted from the third output/input end, thereby ensuring the unidirectionality of the light path.

To sum up, the embodiment of the utility model provides a reflection-type optical circulator has that the structure size is little, preparation simple process, advantage with low costs, satisfies the demand of wavelength division multiplexing single fiber bidirectional transmission module in the data center.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, but that the features of the various embodiments of the invention may be partially or fully coupled to each other or combined and may cooperate with each other and be technically driven in various ways. Numerous obvious variations, rearrangements, combinations, and substitutions will now occur to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims (7)

1. A reflective optical circulator, comprising:

the optical fiber collimator is used for emitting a first light beam; the optical fiber collimator comprises a plurality of optical waveguide chips or a plurality of optical fiber pins;

the optical fiber collimator at least comprises a first output end, a second output/input end and a third output/input end; wherein the central axis directions of the first output end, the second output/input end and the third output/input end are parallel to each other and in a first plane;

the polarization beam splitter prism, the polarization conversion assembly, the light beam deflection assembly, the first Faraday rotation sheet and the reflective lens are sequentially positioned on the first light beam propagation path; the light beam incident to the reflective lens is parallel to the light beam emitted after being reflected by the reflective lens;

the first light beam output by the first output terminal is received by the second output/input terminal; the first light beam output by the second output/input terminal is received by the third output/input terminal.

2. The reflective optical circulator of claim 1, wherein the polarization splitting prism includes a rhombus prism and a right-angle prism;

the rhombic prism and the right-angle prism are arranged in a gluing mode; the gluing surface is plated with a polarization beam splitting film.

3. The reflective optical circulator of claim 1, wherein the fiber collimator further includes a collimating lens;

the collimating lens is used for collimating the first light beam.

4. The reflective optical circulator of claim 1, wherein the beam deflecting assembly includes a wollaston prism;

the Wollaston prism comprises two prisms which are adjacent to each other, and the optical axes of the two prisms are vertical to each other.

5. The reflective optical circulator of claim 1, wherein the polarization conversion assembly comprises a glass plate, a half-wave plate, and a second faraday rotator plate;

the glass sheet is positioned on the propagation path of the second light beam emitted by the polarization beam splitter prism;

the half-wave plate is positioned on a propagation path of the third light beam emitted by the polarization beam splitter prism; the third light beam is perpendicular to the direction of propagation of the second light beam;

and the second Faraday optical rotation plate is positioned on the propagation paths of the second light beam after passing through the glass plate and the third light beam after passing through the half-wave plate.

6. The reflective optical circulator of claim 5, wherein the half-wave plate has a fast axis direction at an angle of 45 ° to the first plane.

7. The reflective optical circulator of claim 1, wherein the reflective lens includes a convex spherical surface and a flat surface, the flat surface being located at a back focal plane of the convex spherical surface.

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