JP2512597Y2 - Optical connector adapter for single polarization fiber - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to an optical connector adapter for optically coupling optical fibers with each other in optical communication, optical measurement, etc., and is particularly used for connecting a single polarization fiber. The present invention relates to an optical connector adapter for a single polarization fiber that prevents reflected return light.

(Prior Art and its Problems) An optical connector is composed of an adapter and a plug.

FIG. 3 is a perspective view in which a part of a conventional adapter is cut away. In the figure, 1 is a split sleeve, and 2a and 2b are male screws.

A plug having a female screw is attached to the end of the optical fiber, and when the optical fiber is connected, this plug is screwed and fixed to the male screw 2a, 2b. Further, the optical fiber is attached with a ferrule for holding the tip portion, and when the plug is connected and fixed, the ferrule is inserted into the split sleeve to position and fix the optical fiber. Therefore, when the two optical fibers to be optically coupled are connected and fixed to their male screws 2a and 2b and inserted into the split sleeve 1 and positioned and fixed, when the light is emitted from one optical fiber Can be incident on the other optical fiber and can be optically coupled to each other.

However, in the above conventional example, a part of the light is reflected by the end face of the optical fiber or the like to return light, and the laser light (LD) of the light source is adversely affected by the return light, such as a drop in output.

In order to prevent this reflected return light, it is conceivable to incorporate an optical isolator utilizing the Faraday effect into the adapter.

However, the conventional optical isolator uses a large number of expensive parts such as a magneto-optical crystal having a Faraday effect, a polarizer, an analyzer, and a magnet that gives a magnetic field to the magneto-optical crystal, and thus it is difficult to reduce the size and cost. Is.

In addition, since the polarization state of light transmitted in a normal multimode or single mode optical fiber is changed due to the bending of the fiber, etc., the one using the optical isolator as described above has the most forward loss. Even if the optical fiber and the adapter are aligned so as to be reduced, there is a drawback that the forward loss changes because the polarization plane of the light incident on the polarizer changes depending on the bending state of the optical fiber.

For such a normal multimode or single mode optical fiber, there is known a single polarization fiber that allows only a single polarization component to pass in a single mode without being affected by bending of the fiber. If this single polarization fiber is connected to an adapter using an optical assulator, the forward loss will not change due to bending of the fiber. However, as described above, the optical isolator has a large number of components, and it is difficult to reduce the size and cost, so that it is impossible to solve all the above drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide an optical connector adapter in which a single polarization fiber is connected to prevent reflected return light, and the size and cost can be easily reduced.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention is designed such that the end faces of optical fibers face each other and are positioned and fixed, and the light emitted from one end face is incident on the other end face of the optical fibers. In an optical connector adapter that is optically coupled, a magneto-optical crystal that produces a Faraday effect when a magnetic field is applied between the end faces of both optical fibers is arranged, and the optical fiber passes only a single polarization component. It is a single polarization fiber and the polarization directions of the end faces of the optical fiber are positioned at an angle of 45 ° to each other, and when the light emitted from the one end face passes through the magneto-optical crystal, the polarization face Is 45
It shall be rotated and incident on the other end face.

(Operation) Since the present invention is configured as described above, when light emitted from one single polarization fiber positioned and fixed to the optical connector adapter passes through the magneto-optical crystal in the optical connector adapter, The plane of polarization is rotated 45 °. In addition, the polarization directions of the end faces of the single polarization fiber are positioned at an angle of 45 ° to each other, and when the light emitted from one end face passes through the magneto-optic crystal, the polarization face is rotated by 45 °. The polarization direction of the exit side single polarization fiber end face with respect to the polarization direction of the exit side single polarization fiber end face. The wave front is 45 ° in the same direction as the direction of rotation by the magneto-optical crystal.
The light whose polarization plane is rotated by 45 ° is incident on the other single polarization fiber on the incident side with very little forward loss. At this time, a small amount of light is reflected by the end face of the single polarization fiber and passes through the magneto-optic crystal again, but when it passes, the polarization plane is rotated by 45 °, so Since they are orthogonal to each other, they do not enter the single polarization fiber on the exit side.

(Embodiment) FIGS. 1 and 2 show an embodiment of the present invention.
FIG. 1 is a vertical sectional view of an optical connector adapter for a single polarization fiber of this embodiment, and FIG. 2 is a single polarization fiber attached to the optical connector adapter for a single polarization fiber of this embodiment by a plug. It is a longitudinal cross-sectional view showing a state of being positioned and fixed. The same parts in FIGS. 1 and 2 are designated by the same reference numerals.

In Fig. 1, A and B are housings, 1 is a split sleeve, and 2
The parts indicated by a and 2b form male threads. Further, 3 is a magneto-optical crystal having a Faraday effect (Faraday rotator), and 4 is a magnet which gives a saturation magnetic field parallel to the optical axis to the Faraday rotator 3. Reference numerals 5a and 5b are lenses, and 6a and 6b are holding members for the lenses 5a and 5b, respectively, and the Faraday rotator 3 is held by the holding members 6a and 6b when aligned. When the ferrules are inserted into the holding members 6a and 6b through the insertion holes indicated by 7a and 7b, the ferrules are brought into contact with the end faces of the holding members to position the single polarization fiber.

In FIG. 2, 8a and 8b are plugs and 9a,
The portions indicated by 9b are connected and fixed to the male screws 2a and 2b by female screws. 10a, 10b are positioning keys for plugs 8a, 8b, 11
a and 11b are ferrules, and 12a and 12b are single polarization fibers. Note that the single polarization fiber 12a is on the output side and 12b is on the input side.

In addition, ferrules 11a and 11b and single polarization fibers 12a and 12b
For example, it is assumed that the plugs 8a and 8b are provided with a rotation adjusting mechanism so that they can rotate freely, and the rotation adjusting mechanism of the plugs 8a and 8b allows polarization of the single polarization fiber 12b with respect to the polarization plane of the single polarization fiber 12a. It is assumed that the wavefront is rotated and fixed so as to form an angle of 45 ° in the same direction as the rotation direction of the Faraday rotator 3 of the polarization plane of the emitted light.

The linearly polarized wave transmitted through the single polarization fiber 12a is collimated by the lens 5a, is incident on the Faraday rotator 3, and its polarization plane is rotated by 45 ° around the optical axis and is condensed by the lens 5b to form a single polarization. It is incident on the wave fiber 12b. The polarization plane of the single polarization fiber 12b is fixed by rotating the polarization plane of the Faraday rotator 3 about the optical axis by 45 ° in the same direction as the polarization plane of the light is rotated by the Faraday rotator 3. Therefore, the light whose polarization plane is rotated by 45 ° by the Faraday rotator 3 has very little loss and is incident on the single polarization fiber 12b and transmitted.

On the other hand, slight reflected light when light is incident on the single polarization fiber 12b or light transmitted through the single polarization fiber 12b is rotated by the Faraday rotator 3 by 45 ° on the polarization plane and the polarization plane is changed. Is orthogonal to the plane of polarization of the single polarization fiber 12a, and therefore is not incident on the single polarization fiber 12a and transmitted.

Also, since the single polarization fibers 12a and 12b can be freely rotated, it is easy to switch the single polarization fiber 12b to the output side and the single polarization fiber 12a to the input side simply by adjusting the rotation adjustment mechanism. You can

FIGS. 4 (a) and 4 (b) show switching of the incoming and outgoing directions, and FIG. 4 (a) shows the polarization plane state when the single polarization fiber 12b is on the incident side and the single polarization fiber 12a is on the outgoing side. FIG. 2B is a diagram showing a polarization plane state when the single polarization fiber 12b is switched to the emission side and the single polarization fiber 12a is switched to the incidence side. When the light propagation direction is reversed from the state of (a), the single polarization fiber 12b is rotated counterclockwise by 90 ° by the rotation adjusting mechanism to the state of (b). Since the input / output direction can be switched by adjusting the rotation adjustment mechanism in this way, when you want to reverse the light propagation direction, you do not have to bother with removing the connector adapter and re-installing it in the opposite direction. Its practicality is extremely high.

In this embodiment, the lens 5 is provided on both sides of the Faraday rotator 3.
Although a and 5b are arranged, the present invention is not limited to this, and the lens may not be arranged and the ferrules 11a and 11b may be inserted into the Faraday rotator 3 to a position near or adjacent to them. Good.

In this embodiment, the single polarization fiber 12 is attached to the plugs 8a and 8b.
Although the example in which the rotation adjusting mechanism of a and 12b is provided has been described, the present invention is not limited to this.
The male screws 2a and 2b of each are provided with notches for angular alignment at intervals of 45 ° around the optical axis, and the alignment keys 10a and 10b of the plugs 8a and 8b are provided with the polarization plates of the single polarization fibers 12a and 12b. By providing a protrusion at a position corresponding to the wave front, connect the plug by aligning the notch and the protrusion at a position where the protrusion on the plug 8a side and the protrusion on the plug 8b side form an angle of 45 ° around the optical axis. Good.

(Effect) With the configuration as described above, since the single polarization fiber is used, there is no change in the polarization state due to bending of the fiber or the like, and it is possible to prevent deterioration of the forward loss. Further, a polarizer and an analyzer, which are indispensable for the construction of the conventional optical isolator, are not required, and it is easy to reduce the size and cost. Moreover, since the incident side and the emitting side of the single polarization fibers can be easily switched, the practicality of various measurements and the like is extremely high.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of an optical connector adapter for a single polarization fiber, and FIG. 2 is an optical connector adapter for a single polarization fiber. It is a longitudinal cross-sectional view showing a state in which a single polarization fiber is connected. FIG. 3 is a perspective view in which a conventional adapter is partially cut away. FIG. 4 shows an embodiment of the present invention, (a) shows a state of polarization plane when the single polarization fiber 12b is on the incident side and the single polarization fiber 12a is on the emission side, (b). Single polarization fiber
FIG. 9 is a diagram showing a polarization plane state when 12b is switched to the exit side and single polarization fiber 12a is switched to the entrance side. 1: Split sleeve 3: Magneto-optical crystal (Faraday rotator) 4: Magnet 5a, 5b: Lens 8a, 8b: Plug 11a, 11b: Ferrule 12a, 12b: Single polarization fiber

Claims (1)

(57) [Scope of utility model registration request] 1. An optical connector adapter in which end faces of optical fibers are positioned and fixed so as to face each other, and light emitted from one end face is incident on the other end face to optically couple the optical fibers with each other. A magneto-optical crystal that generates a Faraday effect of rotating the polarization plane of passing light by 45 ° by applying a magnetic field between the fiber end faces and a magnet that applies the magnetic field in a certain direction to the magneto-optical crystal are integrally fixed, The optical fiber is a single polarization fiber that allows only a single polarization component to pass, and the end faces of both optical fibers are placed in either of the first and second states in which the mutual polarization directions form an angle of 45 °. A rotation adjusting mechanism for switching is provided, and the first
In this state, the light emitted from one end face of the optical fiber passes through the magneto-optical crystal and enters the other end face of the optical fiber,
When the light propagating direction is reversed, the rotation adjusting mechanism switches to the second state, and the light emitted from the other optical fiber end face passes through the magneto-optical crystal and enters the one optical fiber end face. An optical connector adapter for a single polarization fiber characterized by the above.