JPS5810726B2 - optical circulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, output light is obtained at a second port based on the incident light on the first port, and output light is obtained at the third port based on the incident light on the second port. An optical circular lake in which light emitted from the fourth port is obtained based on the light incident on the third port, and light emitted from the first port is obtained based on the light incident on the fourth port. This invention relates to improvements in optical circulators that have improved functionality.

As shown in FIG. 1, this type of optical circulator is conventionally designed so that the angle between the polarization direction of the incident light and that of the output light is approximately 45 degrees by receiving a predetermined magnetic field in the thickness direction. magneto-optical effect plate 1 and its opposing surfaces 2
It has polarizing prisms 3 and 4 arranged to face each other in a and 2b, respectively, and now the thickness direction of the magneto-optic effect plate 1 is Z.
The axial direction, the plane perpendicular to the Z-axis direction is the X-Y plane,
When the mutually extending directions perpendicular to each other on the Y plane are the X-axis direction and the Y-axis direction, and the planes orthogonal to the X-axis direction and the Y-axis direction are respectively the Y-Z plane and the X-Z plane, a polarizing prism 3
If the plane 5 parallel to the X-Z plane of the polarizing prism 4 is set as the first port P1 and the linearly polarized light L1 in the X-axis direction is incident as incident light from the first port, then
Linearly polarized light L1' in a direction tilted by 45 degrees with respect to the Y-axis direction is outputted from a surface 6 which is parallel to the surface rotated by approximately 45 degrees on the X-Y plane with respect to the plane as the second port. 45 in the Y-axis direction from port P2 of text box 2
If the linearly polarized light L2 in the tilting direction is made incident as incident light, then the linearly polarized light L2' in the Y-axis direction is transmitted from the surface 7 of the polarizing prism 3 parallel to the X-Y plane to the third port P3. It is obtained as an emitted light and is further transmitted to the third port P.
3, if the linearly polarized light L3 in the Y-axis direction is incident as the incident light, then based on this, it is used as the fourth port P4 from the surface 8 of the polarizing prism 4 parallel to the X-Y plane at 45 degrees with respect to the Y-axis direction. If the linearly polarized light L3' in the direction of inclination is obtained as the output light, and if the linearly polarized light L4 in the direction of inclination of 45° with respect to the Y-axis direction is made incident as incident light from the fourth port P4, the A configuration has been proposed in which linearly polarized light L4' in the X-axis direction can be obtained as output light from one port.

However, in the case of such a conventional optical circulator, unless the incident light on the first port P1 has a linearly polarized component in the X-axis direction, no output light is obtained at the second port P2, and the Unless the incident light has a linearly polarized component in a direction inclined at 45 degrees with respect to the Y-axis direction, no output light will be obtained at the third port. Unless the incident light has a linearly polarized component tilted by 45 degrees with respect to the Y-axis direction, no output light will be obtained from the fourth port, and furthermore, unless the incident light to the fourth port has a linearly polarized component tilted at 45 degrees with respect to the Y-axis direction, no output light will be obtained from the first port. No output light is obtained,
Therefore, if the incident light to the first port has a linearly polarized component in the X-axis direction and a linearly polarized component in the direction orthogonal to this, the output light obtained from the second port will be different from the incident light. If the incident light to the port of text box 2 has a linearly polarized component in a direction inclined at 45 degrees with respect to the Y-axis direction and a linearly polarized component in a direction perpendicular to this, the third The output light obtained from the port is obtained with a certain loss compared to the input light,
Furthermore, if the incident light to the third port has a linearly polarized component in the Y-axis direction and a linearly polarized component in the direction orthogonal to this, the output light obtained from the fourth port will have a large loss with respect to the incident light. , and furthermore, the fourth
If the incident light to the first port has a linearly polarized component tilted at 45 degrees with respect to the Y-axis direction and a linearly polarized component perpendicular to this, the output light obtained from the first port will be different from the incident light. Gains come at a cost.

Therefore, in the case of the above-mentioned conventional optical circulator, it is assumed that multi-mode light is obtained from an optical waveguide such as an optical fiber, and when that light is the above-mentioned incident light, the output light based on the incident light is the incident light. It had the disadvantage that it was obtained with a certain loss to light.

Therefore, the present invention aims to propose a novel optical circulator of this kind that does not have these drawbacks, which will become clear from the following detailed description of embodiments of the present invention with reference to the drawings.

FIG. 2 shows a first embodiment of the present invention, in which the first optical system A
1, and second and third optical systems A2 and A3 arranged opposite to each other with the optical system A2 and A3 sandwiched therebetween.

The first optical system A1 includes first and second birefringent crystal plates B1 and B2, which are arranged facing each other with a predetermined interval, and a predetermined birefringent crystal plate arranged between the second birefringent crystal plates B1 and B2. A magneto-optic effect board which is made to receive a magnetic field in the thickness direction so that the angle between the polarization direction of the incident light and that of the outgoing light is obtained by a 45° intertwining path, and a birefringent crystal board Bj and B2, for example, the birefringent crystal plate B2 and the magneto-optic effect plate are disposed facing each other, and the angle between the polarization direction of the incident light and that of the output light is approximately 45°. The optically active or anisotropic crystal plate E thus obtained, and the converging lens disposed on the surface of the birefringent crystal plate B1 opposite to the birefringent crystal plate B2 side and facing the birefringent crystal plate B1. It is composed of F.

As is clear from reference to FIG. 3, the optical system A2 of the text box 2 includes a first branching/synthesizing circuit H1 consisting of a third birefringent crystal plate B3 and a converging lens G1 disposed opposite thereto. 1 and a third optical waveguide, for example, a first optical waveguide made of an optical fiber.
As is clear from the figure, a first optical waveguide, which is disposed with one free end surface a facing one surface C of the birefringent crystal plate B3 via a converging lens G, is connected to a second optical waveguide similar to 1. 1 and 2 in the optical waveguide, and 1 and 2 in the first and second optical waveguides arranged with one free end surface a facing the other surface d of the birefringent crystal plate B3 with a predetermined distance from each other. 3 and 4 are constructed as third and fourth optical waveguides similar to those of 2.

In this case, in the branching/combining circuit H1, light containing two linearly polarized components in mutually orthogonal directions is propagated through the optical waveguide 2 toward the end face d, and the light is transmitted from the end face a to the incident light ( If the incident light QO enters the birefringent crystal plate B3 from the surface C side through the lens G1, the light beams are orthogonal to each other within the birefringent crystal plate B3. The light is split into two linearly polarized components, each of which is obtained as an output light (denoted as Q1 and Q2, respectively) from a position centered on a point on the surface d that maintains a predetermined interval, and then The two output lights Q1 and Q2 thus obtained enter the optical waveguides 3 and 4 from their end surfaces a, and these two output lights Q1 and Q2 enter the optical waveguides 3 and 4 respectively. The above-mentioned output lights Q1 and Q2 are made to propagate in the direction opposite to the end face d side of the optical waveguide 3 and 4 in the direction opposite to the end face d side of the optical waveguide. If similar lights are respectively propagated and emitted from the respective end faces a, then those lights will be transmitted to the birefringent crystal plate B.
3 from its surface d side, and these are combined in the birefringent crystal plate B3, and the combined light is reflected from the above-mentioned incident light QO from a position centered on a predetermined point on the surface C. The same light is emitted, enters the optical waveguide 2 from its end surface a through the lens G1, and propagates into the optical waveguide 2 in the direction opposite to its end surface d. This is how it is done.

Further, the third optical system A3 has the same configuration as the second optical system A2, so a detailed explanation thereof will be omitted, but like the second optical system A2, the first branching/synthesizing circuit H1 has the same structure as the second optical system A2. A fourth birefringent crystal plate B4 and converging lens G2 corresponding to the corresponding birefringent crystal plate B3 and converging lens G1, respectively.
A second branching/synthesizing circuit H2 consisting of the first, second, third and fourth optical waveguides 1. 2. 5th corresponding to 3 and 4 respectively. 6th. 5°K for the seventh and eighth optical waveguides
6. 7 and 8.

In this case, the thickness direction of the birefringent crystal plate B1 of the optical system A1 of Kintetsu 1 is the Z-axis direction, and the plane orthogonal to the Z-axis direction is the X-Y
The mutually orthogonal extending directions on the X-Y plane are the X-axis direction and the X-axis direction, and the X-axis direction and the plane orthogonal to the X-axis direction are the Y-Z plane and the X-Z plane, respectively. time, 1st
The birefringent crystal plates B1 and B2, the magneto-optic effect plate, and the optically active or anisotropic crystal plate E in the optical system A1 are arranged with their planes parallel to the X-Y plane. In addition, the lens F is arranged with its optical axis in the Z-axis direction.

1. to the optical waveguide of optical system A2 of text box 2. 3 and 4 are
One end face of 1 on the optical waveguide and 3 and 4 on the optical waveguide.
with the other end face of the
- The surface e of the birefringent crystal plate B1 of the first optical system A1 on the opposite side to the birefringent crystal plate B2 side, so that the birefringent crystal plate B1 of the first optical system A1 is located on the first plane parallel to the Y plane with a predetermined distance from each other. 3. facing the optical waveguide through the lens F. They are arranged sequentially in the order of Kl and 4.

In this case, the optical waveguides Kl, 3, and 4 are actually arranged in such a manner that their free ends lie on a plane parallel to the common X-Y plane. be.

Furthermore, 5. is attached to the optical waveguide of the third optical system A3. 7 and 8 have one end face of 5 on the optical waveguide and the other end face of 7 and 8 on the optical waveguide, and their optical axes are parallel to the Z-Y plane common to them. The first plane is located on a second plane, which may be the same as the first plane, at a predetermined distance from each other.
The optical waveguide 7. to 5
and 8 are arranged in sequence.

In this case, 5. In addition, 7 and 8 are arranged such that their free end faces lie on a plane parallel to the common X-Y plane.

Furthermore, as will become clear later, the lens F is part of the second optical system A.
1 to the optical waveguide of 2. 5. The light from the free end surfaces of A3 and A3 is transmitted to the optical waveguide of the third optical system A3. 7 and 8 on a predetermined free end surface of the optical waveguide of the third optical system A3. The light from the free end surfaces of 7 and 8 is transferred to the optical waveguide Kl of the second optical system A2, 3 and 4.
It is configured to converge onto a predetermined free end face among the free end faces of the free end face.

Birefringent crystal plates B1 and B2 of optical system A1 of text box 1 are arranged in such a manner that their optical axes lie on a third plane parallel to the common Z-Y plane. It is something.

The above is the configuration of the first embodiment of the present invention. According to this configuration, the birefringent crystal plate B1 side of the lens F on the optical axis of the lens F of the optical system A1 of Kintetsu 1 are the points on the opposite side and the points on the opposite side of the optical rotation or anisotropic crystal plate E of the birefringent crystal plate B2 are points M1 and M2, respectively, and between the lens F and the birefringent crystal plate B1; the birefringent crystal Between the plate B1 and the magneto-optic effect plate; between the magneto-optic effect plate and the optically active or anisotropic crystal plate E; between the optically active or anisotropic crystal plate E and the birefringent crystal plate B2
and the optical rotation of the birefringent crystal plate B2 or the anisotropic crystal plate E
The spatial regions on the opposite side are Z1; Z2; Z3; Z4, respectively.
; and Z5, as shown in FIG. 4 when viewed from area Z1 at point M1, linearly polarized light 811 in the X-axis direction and linearly polarized light S21 in the Y-axis direction are both centered 011 and 021 on the light of lens F. Two linearly polarized lights such as those that exist on the axis8
10 and 520 (not shown) are arranged, the center is 011 in area Z1 as shown in FIG.
and linearly polarized light 8 existing on the same point as shown in 021.
Linearly polarized lights S11 and S21 having the same polarization direction as those based on S10 and S20 are mutually polarized in the Y-axis direction as shown by centers 012 and 022, respectively, due to the presence of the birefringent crystal plate B1 in region Z2. The linearly polarized lights S11 and S can be separated from each other.
Linearly polarized lights 812 and S22 having the same polarization direction as those based on 21 are mutually Y as shown by centers 013 and 023, respectively, due to the presence of a magneto-optic effect plate in region Z3.
The linearly polarized lights S13 and 823 whose polarization directions are rotated clockwise by approximately 45 degrees with respect to their polarization directions based on the linearly polarized lights S12 and 822 separated in the axial direction have optical rotations or differences in the region Z4. Due to the presence of the oriented crystal plate E, the centers of the linearly polarized lights 813 and 823 are spaced apart from each other in the Y-axis direction as shown by 014 and 024, respectively. The linearly polarized lights 814 and S24 whose polarization directions are rotated clockwise are based on the linearly polarized lights 814 and S24 whose centers lie on the same point as indicated by 015 and 025, respectively, due to the presence of the birefringent crystal plate B2 in the region Z5. Linearly polarized light 815 with the same polarization direction as the polarization direction of
and 825 are obtained, and therefore, on the X-Y plane including point M2, linearly polarized light 515 (not shown) whose polarization direction based on linearly polarized light S10 is the Y-axis direction and linearly polarized light 515 (not shown) whose polarization direction is based on linearly polarized light S20 is the X-axis direction. Linearly polarized light 525 (not shown) is obtained with their centers both on the optical axis of the lens F.

As shown in FIG. 5, when looking at point M2 in area Z5, linearly polarized light 815' in the Y-axis direction and linearly polarized light 825' in the X-axis direction are both centered 015' and 025' on the optical axis of lens F. If a light source capable of producing two linearly polarized lights 816' and s26' (not shown) as shown in FIG. ′, each linearly polarized light 8 existing on the same point
Linearly polarized lights 815' and 825' in the same direction as their polarization directions based on 16' and 826' are centered at 014' and 024, respectively, due to the presence of the birefringent crystal plate B2 in region Z4.
The linearly polarized lights 81 are spaced apart from each other in the Y-axis direction as shown by '.
Linearly polarized lights 814' and 824' with the same polarization direction as those based on 5' and 825' are centered at 013' due to the presence of the optically active or anisotropic crystal plate E in region Z3.
and 023', a straight line in a direction that can be rotated counterclockwise by approximately 45 degrees with respect to the polarization directions of the linearly polarized lights 814' and 824' separated from each other in the Y-axis direction. The polarized lights 813' and 823' are centered at 012' and 02 due to the presence of the magneto-optic effect plate in region Z2.
As shown by 2', linearly polarized light beams 8 are spaced apart from each other in the Y-axis direction.
Linearly polarized lights 812' and 822', which can be rotated approximately 45 degrees counterclockwise relative to their polarization directions based on 13' and 823', respectively, are present in region Z1 due to the presence of birefringent crystal plate B1. Therefore, the centers of the linearly polarized lights 812' and 822' are spaced apart from each other in the Y-axis direction by a distance greater than the distance between the centers 012' and 022', respectively, as shown by 011' and 021', respectively. Linearly polarized lights 811' and 821' in the same direction as the polarization directions based on linearly polarized lights 812' and 822' are obtained, and therefore the polarization direction based on linearly polarized lights 816' is changed to Linearly polarized light 820' (not shown) whose polarization direction is the X-axis direction based on linearly polarized light SIO' (not shown) that is axially polarized and linearly polarized light 826'
are obtained in such a manner that their centers are largely spaced apart in the Y-axis direction.

Therefore, according to the first embodiment of the present invention described above, the optical waveguide of the second optical system A2 has 1. 3 and 4 of the free end surfaces a facing the birefringent crystal plate B1 of the first optical system A1.
5. axial spacing; and the optical waveguide of the third optical system A3.
If the distance in the Y-axis direction between the end faces facing the birefringent crystal plate B2 of the first optical system A1 in 7 and 8 is appropriately selected in advance, the second optical system A1 as shown in FIG. If light having two linearly polarized light components whose polarization directions are orthogonal to each other is made to enter the optical waveguide of the optical system A2 as the first port P1, it becomes the first optical waveguide. A second embodiment in which the system A1 passes through an optical path in which two linearly polarized light components whose polarization directions are orthogonal to each other between the birefringent crystal plates B1 and B2 are separated from each other in the Y-axis direction as shown by solid lines and dotted lines, respectively. The light passes through the optical waveguide 5 of the third optical system A3 as a second port P2, and light having two linearly polarized components whose polarization directions are orthogonal to each other is obtained as the output light Ll'. Also, as shown in Figure 7, the third
Similarly, if light having two linearly polarized components whose polarization directions are orthogonal to each other is made to enter the optical waveguide of the optical system A3 from the second port P2 as the incident light L2, it will become the first light beam. An optical path in which two linearly polarized light components whose polarization directions are orthogonal to each other from the position of the birefringent crystal plate B2 to the lens F side of the optical system A1 are spaced apart from each other in the Y-axis direction as shown by solid lines and dotted lines, respectively. The two lights pass through the optical waveguide of the second optical system A3 through 3 and 4, respectively, and enter the branching/combining circuit H1. When this is connected to the third port P3, light having two linearly polarized components whose polarization directions are orthogonal to each other is obtained as the output light L2', and as shown in FIG. 2, that is, from the third port P3, the polarization directions are similarly orthogonal to each other.
When light having two linearly polarized components is incident as incident light L3, it passes through the branching/synthesizing circuit H1 to the optical waveguide as two linearly polarized components whose polarization directions are orthogonal to each other. each separately, and the first optical system A
A second embodiment in which two linearly polarized light components whose polarization directions are orthogonal to each other pass through optical paths that are separated from each other in the Y-axis direction.
The two lights pass through the optical waveguides 7 and 8 of the third optical system A3, respectively, to the branching-combining circuit H.
2, and therefore, the light having two linearly polarized components whose polarization directions are orthogonal to each other is obtained as the output light L3' by passing it through the optical waveguide 6 to the fourth port P4, and furthermore, as shown in FIG. If light having two linearly polarized components whose polarization directions are orthogonal to each other is made to enter the optical waveguide of the third optical system A3 from the fourth port P4 as the incident light L4, as shown in FIG. The light passes through the optical waveguide via the branching/combining circuit H2 as two linearly polarized components whose polarization directions are orthogonal to each other, and the first
In the optical system A1 up to the birefringent crystal plate B1, two linearly polarized light components whose polarization directions are orthogonal to each other are Y.
Similarly, light having two linearly polarized components whose polarization directions are orthogonal to each other passes through optical paths spaced apart from each other in the axial direction and enters the optical waveguide of the second optical system A2 from the first port P1. This is obtained as the emitted light L4'.

Therefore, according to the first embodiment of the present invention described above, 1 and 2 are connected to the first and third optical waveguides of the second optical system A2, respectively.
ports 5 and 6 in the optical waveguide of the third optical system A3 as second and fourth ports, respectively. Second. Based on the incident light on the third and fourth ports, respectively, the second. Third. The function of the conventional optical circulator described above in FIG. 1 is obtained, in which output light is obtained at the fourth and first ports, and in this case, multimode light is obtained from an optical waveguide such as an optical fiber. The light shall be the first. Second. As for the incident light to the third and fourth ports, the second, third, and third ports are based on the incident light. The output light obtained at the fourth and first ports is not obtained as a result of a loss with respect to the input light as in the case of the conventional optical circulator described above in FIG. It has the following characteristics.

Next, the second embodiment of the present invention will be described.Although the detailed explanation of the drawings will be omitted, the optical rotation and anisotropy of the structure of the first embodiment of the present invention described above in FIG. The birefringent crystal plate B5 is substituted for the birefringent crystal plate E, and the birefringent crystal plate B is replaced accordingly.
1 has its optical axis on the third plane parallel to the Z-Y plane as in the case of FIG. 2, but the birefringent crystal plates B2 and B5 Approximately 45 degrees with the plane of 3
The structure is the same as that shown in FIG. 2, except that they are arranged on the fourth and fifth planes, which form an angle of approximately 90 degrees with each other. have

The above is the configuration of the second embodiment of the present invention. According to this configuration, although detailed explanation is omitted, the same thing as the case described above in Figures 4 and 5 can be considered. is the fourth
As shown in FIGS. 10 and 11 with the same reference numerals assigned to corresponding parts in FIGS. 4 and 5, results similar to those described above in FIGS. 4 and 5 can be obtained. The relationship between the incident light and the emitted light can be obtained in accordance with the above-described relationship in FIGS. 6 to 9.

Therefore, the second embodiment of the present invention described above also provides a function as an optical circulator having the same characteristics as the first embodiment of the present invention described above.

The above description has only shown a small number of embodiments of the present invention, and detailed description will be given herein, as shown in FIG. 12, for example, where parts corresponding to those in FIG. However, the lens F is omitted in the configuration shown in FIG. or1
For example, the plate surface of the birefringent crystal plate E1 may be made into a curved surface g and the same function as that of the lens F may be added to it. As shown in the figure, the detailed explanation is omitted, but in the configuration shown in Figure 2, the surface of the magneto-optic effect plate is
- In the case where the magneto-optic effect plate is placed on a plane that is inclined to a plane parallel to the Y plane, and a reflective film and an i are attached to the opposite surfaces of the magneto-optic effect plate, and by doing so, The magneto-optic effect plate shown in FIG. It is also possible to make a modification such as exchanging the positions of the plate and the optically active or anisotropic crystal plate E, and of course such a modification can also be made in the second embodiment of the present invention. Yes, and various other modifications may be made.

[Brief explanation of drawings]

Figure 1 is a systematic diagram showing a conventional optical circulator.
FIG. 2 is a schematic diagram showing the first embodiment of the optical circulator according to the present invention, FIG. 3 is a schematic diagram showing an example of its branching/combining circuit, and FIGS. 4 and 5 are 2 is a diagram showing the aspect of linearly polarized light in a spatial region for explaining the first embodiment of the present invention shown in FIG. The line diagrams, FIGS. 10 and 11, which are used to explain the operation, are the same as those shown in FIGS. 4 and 5, respectively, which are used to explain the second embodiment of the optical circulator according to the present invention.
Figures similar to the figure, Figures 12 and 13, are schematic diagrams showing other embodiments of the present invention, respectively. In the figure, AI, A2 and A3 are optical systems, B1 to B4 are birefringent crystal plates, D is a magneto-optic effect plate, E is an optical rotation or anisotropic crystal plate, F is a converging lens, and K1- and 8 are optical waveguide, H
1 and K2 indicate branching/combining circuits, respectively.

Claims (1)

[Claims] 1. Consisting of a first optical system, and second and third optical systems arranged opposite to each other with the first optical system in between, the first optical system has a predetermined optical system. First and second birefringent crystal plates are arranged facing each other with a distance of . The angle between the polarization direction and that of the emitted light is approximately 4
The second optical system includes a first branching/combining circuit having a third birefringent crystal plate, and a first optical waveguide. a second optical waveguide disposed with one free end surface facing one surface of the third birefringent crystal plate; and a third optical waveguide with one free end surface kept at a predetermined distance from each other. and third and fourth optical waveguides arranged to face the other surface of the birefringent crystal plate, the third optical system having a second branching/combining optical system having a fourth birefringent crystal plate. A circuit, a fifth optical waveguide, a sixth optical waveguide disposed with one free end surface facing one surface of the fourth birefringent crystal plate, and one free end surface of the fourth birefringent crystal plate with one free end surface facing each other in a predetermined manner. seventh and eighth optical waveguides arranged to face the other surface of the fourth birefringent crystal plate with a distance therebetween, the first, third and eighth optical waveguides of the second optical system; The optical waveguide No. 4 includes one free end surface of the first optical waveguide and the third and fourth optical waveguides.
The first optical system of the first optical system is arranged such that the other free end surface of the optical waveguide is located at a predetermined distance from the other optical axis of the optical waveguide on the first plane common to them. The above second birefringent crystal plate
The fifth, seventh, and eighth optical waveguides of the third optical system are arranged to face the surface opposite to the birefringent crystal plate side, and the fifth, seventh, and eighth optical waveguides of the third optical system are arranged to face one free end surface of the fifth optical waveguide and The other free end surfaces of the seventh and eighth optical waveguides are arranged such that their optical axes are on a second plane common to them and are spaced apart from each other by a predetermined distance. A second birefringent crystal plate of an optical system is disposed to face a surface opposite to the first birefringent crystal plate, and the first optical system is connected to the first and second birefringent crystal plates. In addition to the magneto-optic effect plate, the first part of the second optical system
The light from one free end surface of the optical waveguide and the other free end surface of the third and fourth optical waveguides is transmitted to the fifth optical system of the third optical system.
or converge onto a predetermined free end surface of one of the two free end surfaces of the optical waveguide and the other free end surface of the seventh and eighth optical waveguides, or conversely, the fifth optical waveguide of the third optical system. Light from one free end surface and the other free end surface of the seventh and eighth optical waveguides is transferred to one free end surface of the first optical waveguide of the second optical system and the third and fourth optical waveguides. a lens means for converging the lens onto a predetermined free end surface of the other free end surface, and a lens means disposed between the first or second birefringent crystal plate and the magneto-optic effect plate so as to face each other. an optically active or anisotropic crystal plate configured such that the angle between the polarization direction of the incident light and that of the output light is approximately 45°; Refractive crystal plates are disposed in such a relationship that their optical axes lie on a third plane common to them, thus directing the first and second optical waveguides of the second optical system to respective third planes. 1
and a third port, the optical circulator is characterized in that it is configured to provide an optical circulator function in which the fifth and sixth optical waveguides of the third optical system are used as the second and fourth ports, respectively. 2 Consists of a first optical system, and second and third optical systems arranged opposite to each other with the first optical system in between, and the first optical system is arranged opposite to each other with a predetermined distance between them. The polarization direction of the incident light and the polarization direction of the output light are changed by receiving a predetermined magnetic field between the first and second birefringent crystal plates arranged facing each other and the first and second birefringent crystal plates. The angle it makes with it is approximately 4
The second optical system includes a first branching/combining circuit having a third birefringent crystal plate, and a first light guide. a second optical waveguide disposed with one free end surface facing one surface of the third birefringent crystal plate; and a third optical waveguide with one free end surface kept at a predetermined distance from each other. and third and fourth optical waveguides arranged to face the other surface of the birefringent crystal plate, and the third optical system includes a second branching optical system having a fourth birefringent crystal plate; a synthetic circuit, a fifth optical waveguide, a sixth optical waveguide disposed with one free end surface facing one surface of the fourth birefringent crystal plate, and one free end surface of the sixth optical waveguide disposed with one free end surface facing each other in a predetermined manner. seventh and eighth optical waveguides arranged to face the other surface of the fourth birefringent crystal plate with an interval of A fourth optical waveguide includes one free end surface of the first optical waveguide and the third and fourth optical waveguides.
The first optical system of the first optical system is arranged such that the other free end surface of the optical waveguide is located at a predetermined distance from the other optical axis of the optical waveguide on the first plane common to them. The above second birefringent crystal plate
The fifth, seventh, and eighth optical waveguides of the third optical system are shown opposite to the surface opposite to the birefringent crystal plate side, and the fifth, seventh, and eighth optical waveguides of the third optical system are located on one free end surface of the fifth optical waveguide and The other free end surfaces of the seventh and eighth optical waveguides are arranged such that their optical axes are on a second plane common to them and are spaced apart from each other by a predetermined distance. A second birefringent crystal plate of an optical system is disposed to face a surface opposite to the first birefringent crystal plate, and the first optical system is connected to the first and second birefringent crystal plates. In addition to the magneto-optic effect plate, the first part of the second optical system
The light from one free end surface of the optical waveguide and the other free end surface of the third and fourth optical waveguides is transmitted to the fifth optical system of the third optical system.
converge on a predetermined free end surface of one free end surface of the optical waveguide and the other free end surface of the seventh and eighth optical waveguides, or conversely, one of the fifth optical waveguides of the third optical system. and the other free end surface of the seventh and eighth optical waveguides are transmitted to one free end surface of the first optical waveguide of the second optical system and the third and fourth optical waveguides. a lens means for converging the light onto a predetermined free end surface of the other free end surface; 5 birefringent crystal plates, the first birefringent crystal plate is arranged with its optical axis on a third plane, and the second and fifth birefringent crystal plates have their optical axes approximately equal to the third plane above.
The first and second planes of the second optical system are arranged on the fourth and fifth planes, which form an angle of 5° and an angle of approximately 90° with each other, respectively, so that the first and second planes of the second optical system An optical circulator function is obtained in which the optical waveguides of the third optical system are used as the first and third ports, respectively, and the fifth and sixth optical waveguides of the third optical system are used as the second and fourth ports, respectively. An optical circulator featuring: