CN214278570U - Compact optical isolator - Google Patents

Abstract

The utility model relates to a compact optical isolator, including metal casing and the first fiber collimator who arranges in proper order from a left side to the right side of encapsulating in the metal casing, first polarization beam splitter, first wave plate, first magneto-optical crystal, second magneto-optical crystal, the second wave plate, second polarization beam splitter and second fiber collimator, keep apart first polarization beam splitter in the core major structure, first wave plate, first magneto-optical crystal, second wave plate and second polarization beam splitter closely laminate in proper order, the axial dimensions who makes optical isolator reduces, optic fibre in first fiber collimator and the second fiber collimator adopts the heat to expand core optic fibre, make the divergence angle of facula reduce, make the radial dimensions of isolator core reduce. The optical isolator adopts fewer components, reduces the size of the isolator core main body in the axial direction and the radial direction, and has the advantages of simple and compact structure, small size, high isolation degree, low insertion loss, low polarization-related loss, low cost and the like.

Description

Compact optical isolator

Technical Field

The utility model relates to an optical communication technical field, concretely relates to compact optical isolator.

Background

The optical isolator is a passive optical device which allows optical signals to pass through in a single direction, and is used for limiting the direction of light, so that the light can be transmitted only in a single direction, the light reflected by the optical fiber echo can be well isolated by the optical isolator, and the transmission efficiency of the optical signals is improved. In modern optical fiber communication, especially 5G applications, the number of optical devices is required to be increased in a limited space to form a highly dense integrated transceiver module or system, and thus in applications where small-sized devices are required, the size of the optical isolator is highly required.

The existing optical isolator CORE is generally composed of a collimator and an isolator CORE (CORE) which are connected with input and output optical fiber ports. Generally, the isolator core adopts a birefringent crystal and a wollaston prism, so that the size of the optical isolator is large, the number of elements is large, the structure is complex, the whole optical device is difficult to miniaturize, and the requirement of the small-size optical device in the 5G era cannot be met.

SUMMERY OF THE UTILITY MODEL

In view of the above, there is a need for a compact optical isolator with simple device structure and convenient installation.

The utility model provides a compact optical isolator, includes the metal casing and encapsulates in first optical collimator, first polarization beam splitter prism, first wave plate, first magneto-optical crystal, second wave plate, second polarization beam splitter prism and the second optical collimator that arranges in proper order from a left side to the right side in the metal casing, first polarization beam splitter prism first wave plate first magneto-optical crystal second wave plate with second polarization beam splitter prism constitutes isolator core main part, first polarization beam splitter prism first wave plate first magneto-optical crystal second wave plate with second polarization beam splitter prism closely laminates in proper order to reduce the radial dimension of isolator core main part.

Further, the first optical fiber collimator, the first polarization splitting prism, the first magneto-optical crystal, the second polarization splitting prism, and the second optical fiber collimator are disposed on a central axis of the metal housing, and the first wave plate and the second wave plate are disposed on an upper half portion of the central axis of the metal housing to change a polarization state of light passing through the upper half portion of the central axis.

Further, the first optical fiber collimator comprises a first optical fiber and a first collimating lens, the second optical fiber collimator comprises a second optical fiber and a second collimating lens, and the first optical fiber and the second optical fiber adopt a thermal core expansion optical fiber so as to reduce the divergence angle of the output light spots of the first optical fiber and the second optical fiber.

Furthermore, a first polarization beam splitting film is arranged in the first polarization beam splitting prism, and an included angle between the first polarization beam splitting film and the horizontal plane is 30-45 degrees; the upper end face of the first polarization splitting prism adopts a plane provided with an optical signal absorption film, and the lower end face of the first polarization splitting prism adopts an inclined plane provided with a high-reflection film.

Furthermore, a second polarization beam splitting film is arranged in the second polarization beam splitting prism, and an included angle between the second polarization beam splitting film and the horizontal plane is 30-45 degrees; and the upper end surface and the lower end surface of the second polarization splitting prism adopt inclined planes provided with high-reflection films.

Further, the first polarization beam splitting film and the second polarization beam splitting film are arranged in axial symmetry with the radial direction of the center point of the isolator core main body as an axis.

Further, the first wave plate and the second wave plate both adopt half-wave plates for polarizing the polarization state of vertically incident polarized light by 90 degrees.

Further, the first magneto-optical crystal and the second magneto-optical crystal both adopt 45-degree Faraday optical rotation sheets, magnetic rings are arranged outside the first magneto-optical crystal and the second magneto-optical crystal, and the polarization state of incident polarized light is changed by the first magneto-optical crystal and the second magneto-optical crystal under the action of a saturated magnetic field.

In the compact optical isolator, the first polarization beam splitter prism, the first wave plate, the first magneto-optical crystal, the second wave plate and the second polarization beam splitter prism in the main structure of the isolator core are sequentially and tightly attached to reduce the axial size of the isolator, and the optical fibers in the first optical collimator and the second optical collimator adopt heat core-expanding optical fibers to reduce the divergence angle of light spots, so that the size of the output light spots of the optical collimator can influence the radial size of the isolator core, and the smaller the diameter of the light spots is, the smaller the radial size of the isolator core is, and the radial size of the isolator core is reduced. The optical isolator adopts fewer components, reduces the size of the isolator core main body in the axial direction and the radial direction, and has the advantages of simple and compact structure, small size, high isolation degree, low insertion loss, low polarization-related loss, low cost and the like. The product of the utility model is simple in structure, easy to produce, low in cost, convenient to popularize.

Drawings

Fig. 1 is an exploded view of a compact optical isolator according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of forward transmission light path of the compact optical isolator according to the embodiment of the present invention.

Fig. 3 is a schematic diagram of a reverse transmission light path of a compact optical isolator according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram (parts are attached) of the isolator core of the compact optical isolator according to the embodiment of the present invention.

Fig. 5 is a schematic structural diagram of a first polarization splitting prism of a compact optical isolator according to an embodiment of the present invention.

Fig. 6 is a schematic structural diagram of a second polarization splitting prism of a compact optical isolator according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to the following embodiments and drawings.

Please refer to fig. 1, fig. 4, fig. 5 and fig. 6, which illustrate a compact optical isolator 100 according to an embodiment of the present invention, including a metal housing, and a first fiber collimator 11, a first polarization beam splitter prism 21, a first wave plate 31, a first magneto-optical crystal 41, a second magneto-optical crystal 42, a second wave plate 32, a second polarization beam splitter prism 22 and a second fiber collimator 12 which are packaged in the metal housing and sequentially arranged from left to right, wherein the first polarization beam splitter prism 21, the first wave plate 31, the first magneto-optical crystal 41, the second magneto-optical crystal 42, the second wave plate 32 and the second polarization beam splitter prism 22 constitute an isolator core main body, the first polarization beam splitter prism 21, the first wave plate 31, the first magneto-optical crystal 41, the second magneto-optical crystal 42, the second wave plate 32 and the second polarization beam splitter prism 22 are tightly attached, the structure of the isolator core main body is compact, and the radial size of the isolator core main body is reduced.

Further, the first optical fiber collimator 11, the first polarization splitting prism 21, the first magneto-optical crystal 41, the second magneto-optical crystal 42, the second polarization splitting prism 22, and the second optical fiber collimator 12 are disposed on the central axis of the metal housing, and the first wave plate 31 and the second wave plate 32 are disposed on the upper half portion of the central axis of the metal housing to change the polarization state of the light passing through the upper half portion of the central axis.

Specifically, the optical isolator includes isolator core main part with locate respectively isolator core main part both ends first fiber collimator 11 with second fiber collimator 12, first fiber collimator 11 with second fiber collimator 12 is used for collimating into parallel beam with the input light respectively and outputs to isolator core main part or will the light that isolator core main part was exported couples to in the optic fibre.

Further, the first fiber collimator 11 includes a first fiber 01 and a first collimating lens, the second fiber collimator 12 includes a second fiber 02 and a second collimating lens, and the first fiber 01 and the second fiber 02 employ a thermal core-expanding fiber to reduce a divergence angle of output spots of the first fiber 01 and the second fiber 02.

Specifically, for the same collimating lens, after the thermal core-expanding optical fiber is adopted, the diameter of an output light spot can be reduced to a half of that of a common optical fiber at the same position, the crosstalk between light paths is reduced, the isolation of a device is improved, the cross section of each element of the optical isolator can be reduced, and the miniaturization effect is realized on the whole volume. The first fiber collimator 11 and the second fiber collimator 12 may collimate the incident first optical fiber 01 and couple the collimated light beam to the corresponding second optical fiber 02.

Further, a first polarization splitting film 213 is disposed in the first polarization splitting prism 21, and an included angle between the first polarization splitting film 213 and a horizontal plane is 30 to 45 degrees; the upper end surface of the first polarization splitting prism 21 adopts a plane provided with an optical signal absorption film 211, and the lower end surface of the first polarization splitting prism 21 adopts an inclined plane 212 provided with a high reflection film. A second polarization splitting film 223 is arranged in the second polarization splitting prism 22, and an included angle between the second polarization splitting film 223 and the horizontal plane is 30-45 degrees; the upper end surface and the lower end surface of the second polarization splitting prism 22 both adopt inclined surfaces 221 and 222 provided with high reflection films. The first polarization splitting film 213 and the second polarization splitting film 223 are disposed axially symmetrically with respect to the radial direction of the center point of the isolator core main body. The first wave plate 31 and the second wave plate 32 both use half-wave plates for polarizing the polarization state of vertically incident polarized light by 90 degrees.

Specifically, the first polarization splitting prism 21 is divided into an upper half of the first polarization splitting prism 21 and a lower half of the first polarization splitting prism 21 along the first polarization splitting film 213, and the first polarization splitting film 213 splits incident light into two polarized lights perpendicular to each other.

Specifically, the second polarization splitting prism 22 is divided into an upper half portion of the second polarization splitting prism 22 and a lower half portion of the second polarization splitting prism 22 along the second polarization splitting film 223, and the second polarization splitting film 223 combines two beams of polarized light incident through the upper half portion of the second polarization splitting prism 22 and the lower half portion of the second polarization splitting prism 22 and perpendicular to each other into one beam.

Specifically, the first wave plate 31 and the second wave plate 32 are disposed on the upper half portion of the central axis of the metal housing, and only change the polarization state of the light passing through the upper half portion of the first polarization splitting prism 21 and then transmit the light to the upper half portion of the second polarization splitting prism 22.

Specifically, the optical signal absorption film 211 is disposed on an upper end surface of the first polarization splitting prism 21, and is configured to absorb the backward beam incident from the second fiber collimator 12.

Further, the first magneto-optical crystal 41 and the second magneto-optical crystal 42 both use 45-degree faraday rotation plates, a magnetic ring (not shown) is disposed outside the first magneto-optical crystal 41 and the second magneto-optical crystal 42, and the first magneto-optical crystal 41 and the second magneto-optical crystal 42 change the polarization state of incident polarized light under the action of a saturation magnetic field.

Specifically, after the incident polarized light passes through the first magneto-optical crystal and the second magneto-optical crystal, the polarization state is deflected by 90 °.

Referring to fig. 2, a schematic diagram of the forward transmission optical path of the compact optical isolator 100 is shown. The first optical fiber 01 inputs signal light, the first collimator 11 collimates the light beam, which is denoted as light beam 100, and emits the light beam into the first polarization splitting prism 21, the first polarization splitting prism 21 can split the light beam into two beams of P light and S light with mutually perpendicular polarization states, wherein the polarization state of the P light transmitted through the first polarization splitting film 213 is parallel to the Z axis, which is denoted as light beam 101, the reflected light is S light, and the polarization state of the S light is perpendicular to the X axis, which is denoted as light beam 102. The light beam 101 passes through said first waveplate 31, said first waveplate 31 deflecting the polarization state of the light beam 101 by 90 °, denoted as light beam 103, i.e. the polarization state of the light beam 103 is parallel to the X-axis. The light beam 102 is not changed in polarization state because it is not passed through the first wave plate 31, and is marked as light beam 104. The polarization states of the light beam 103 and the light beam 104 are the same. As the light beam 103 and the light beam 104 pass through the optical rotation means formed by the first magneto-optical crystal 31 and the second magneto-optical crystal 32, the polarization states of the light beams are simultaneously deflected by 90 °, i.e. the polarization states are both parallel to the Z-axis, denoted as light beam 105 and light beam 106, respectively. The light beam 105 is deflected by 90 with respect to its polarization state by said second wave plate 32, i.e. the polarization state of the light beam is parallel to the X-axis, denoted as light beam 107, as S-light. The beam 106 has not passed through the second waveplate 32 and remains unchanged in polarization, denoted as beam 108, as P light. Beam 107 and beam 108, due to their polarization states being perpendicular to each other, are combined into a beam of light output, denoted as beam 200, by second pbs 22. The light beam 200 is coupled into the second optical fiber 02 via the second fiber collimator 12, and the output coupling of the first optical fiber 01 to the second optical fiber 02 is completed, i.e. the forward transmission of the device is completed.

Referring to fig. 3, a schematic diagram of a reverse transmission optical path of the compact optical isolator 100 is shown. The second optical fiber 02 inputs signal light, the second collimator 12 collimates the light beam, which is denoted as light beam 200, and emits the light beam into the second polarization splitting prism 22, the second polarization splitting prism 22 splits the light beam into two beams of P light and S light with mutually perpendicular polarization states, wherein the light reflected by the second polarization splitting film 223 is S light, the polarization state of the S light perpendicular to the X axis is denoted as light beam 201, the transmitted light is P light, the polarization state of the P light is parallel to the Z axis, and the polarization state of the P light is denoted as light beam 202. The light beam 201 passes through said second wave plate 32, said second wave plate 32 deflecting the polarization state of the light beam 201 by 90 °, denoted as light beam 203, i.e. the polarization state of the light beam 203 is parallel to the Z-axis. The beam 202, however, has not passed through the second waveplate 32 and thus has an unchanged polarization, denoted as beam 204. The polarization states of beam 203 and beam 204 are the same. And then passes through the optical rotation device formed by the second magneto-optical crystal 32 and the first magneto-optical crystal 31, the polarization state of the light beam is not deflected, namely the polarization state is parallel to the Z axis and is respectively marked as a light beam 205 and a light beam 206. The light beam 205 is deflected by 90 ° in polarization by the first wave plate 31, i.e. the polarization of the light beam is parallel to the X-axis, denoted as light beam 207, which is S-light. The beam 206 has not passed through the first waveplate 31 and remains unchanged in polarization, denoted as beam 208, as P light. Because the polarization states of the light beam 207 and the light beam 208 are mutually perpendicular, the light beam is synthesized into a light beam by the first polarization splitting prism 21 and then output to the optical signal absorption film 211, and the light beam cannot be reversely coupled into the first optical fiber 01, so that the reverse isolation function of the device is realized.

As described above, an optical signal is input through the first optical fiber 01 and can be output through the second optical fiber 02; but the optical signal can not be transmitted reversely to the first optical fiber 01 by the second optical fiber 02, so that the function of the polarization-independent optical isolator is realized.

Specifically, in the compact optical isolator 100, an isolator CORE is formed based on a CORE-expanding optical fiber collimator as an input end and an output end, two polarization splitting prisms and a rotation device. The diameter of a light spot input by the CORE-expanding optical fiber is smaller, so that the radial size of the CORE of the isolator can be reduced. In addition, the polarization beam splitter prism can split any beam of unpolarized light into two beams of polarized light perpendicular to each other at a small enough longitudinal distance, and a lateral separation distance with any size is generated; conversely, two beams of polarized light perpendicular to each other may be combined into one beam.

In the above compact optical isolator 100, the first polarization splitting prism 21, the first wave plate 31, the first magneto-optical crystal 41, the second magneto-optical crystal 42, the second wave plate 32 and the second polarization splitting prism 22 in the main structure of the isolator core are sequentially and tightly attached to each other, so that the axial size of the optical isolator 100 is reduced, the optical fibers in the first optical collimator 11 and the second optical collimator 12 adopt core thermal expansion optical fibers, so that the divergence angle of light spots is reduced, the size of the light spots output by the optical collimators can affect the radial size of the isolator core, and the smaller the diameter of the light spots is, the smaller the radial size of the isolator core is, so that the radial size of the optical isolator core is reduced. The optical isolator 100 adopts fewer components, reduces the size of the isolator core main body in the axial direction and the radial direction, and has the advantages of simple and compact structure, small size, high isolation degree, low insertion loss, low polarization-related loss, low cost and the like. The product of the utility model is simple in structure, easy to produce, low in cost, convenient to popularize.

It should be noted that the present invention is not limited to the above embodiments, and other changes can be made by those skilled in the art according to the spirit of the present invention, and all the changes made according to the spirit of the present invention should be included in the scope of the present invention.

Claims (8)

1. The utility model provides a compact optical isolator which characterized in that, include the metal casing and encapsulate in first fiber collimator, first polarization beam splitter prism, first wave plate, first magneto-optical crystal, second wave plate, second polarization beam splitter prism and the second fiber collimator that arranges from a left side to the right side in proper order in the metal casing, first polarization beam splitter prism first wave plate first magneto-optical crystal second wave plate with second polarization beam splitter prism constitutes isolator core main part, first polarization beam splitter prism first wave plate first magneto-optical crystal second wave plate and second polarization beam splitter prism closely laminate in proper order to reduce the radial dimension of isolator core main part.

2. The compact optical isolator according to claim 1, wherein said first fiber collimator, said first polarization splitting prism, said first magneto-optical crystal, said second polarization splitting prism, and said second fiber collimator are disposed on a central axis of said metal housing, and said first wave plate and said second wave plate are disposed on an upper half portion of the central axis of said metal housing to change a polarization state of light passing through the upper half portion of the central axis.

3. The compact optical isolator of claim 1, wherein said first fiber collimator comprises a first optical fiber and a first collimating lens, and said second fiber collimator comprises a second optical fiber and a second collimating lens, said first optical fiber and said second optical fiber employing thermally expanded core fibers to reduce divergence angles of output spots of said first optical fiber and said second optical fiber.

4. The compact optical isolator of claim 1, wherein the first polarization splitting prism has a first polarization splitting film disposed therein, and the first polarization splitting film has an angle of 30 degrees to 45 degrees with respect to a horizontal plane; the upper end face of the first polarization splitting prism adopts a plane provided with an optical signal absorption film, and the lower end face of the first polarization splitting prism adopts an inclined plane provided with a high-reflection film.

5. The compact optical isolator according to claim 4, wherein a second polarization splitting film is disposed in the second polarization splitting prism, and an angle between the second polarization splitting film and a horizontal plane is 30 degrees to 45 degrees; and the upper end surface and the lower end surface of the second polarization splitting prism adopt inclined planes provided with high-reflection films.

6. The compact optical isolator according to claim 5, wherein said first polarization splitting film and said second polarization splitting film are disposed axisymmetrically with respect to a radial direction of a center point of said isolator core body.

7. The compact optical isolator of claim 1, wherein said first wave plate and said second wave plate each employ a half-wave plate for polarizing the polarization state of vertically incident polarized light by 90 degrees.

8. The compact optical isolator according to claim 1, wherein the first and second magneto-optical crystals each employ a 45 ° faraday rotation plate, and a magnetic ring is disposed outside the first and second magneto-optical crystals, and the first and second magneto-optical crystals change the polarization state of incident polarized light under the action of a saturation magnetic field.

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