JPH0679115B2 - Optical fiber type polarization changing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention is an optical fiber type optical polarization device which is composed of an optical fiber and which changes the polarization mode of input polarized light to a desired polarization mode and outputs it. Concerning the appearance change device.

"Prior Art" A conventional optical fiber type polarization changing device of this type is, for example, the magazine "ELECTRONICS LETTERS" 25th, Sep. 1980 Vol.16, N.
o.20, pp.778-780, “Single-mode Fiber Frartiona Wa
ve Devices And Polarization Controllers ". As shown in Fig. 1, this device has an optical fiber 12 wound around a bobbin 11 to form a coil-shaped portion 13.
The optical fibers 12 are extended from the substantially same portion of 12a in the tangential direction of the coiled portion 12a to be opposite to each other to form extension portions 12b and 12c, respectively, and the extension portions 12b and 12c are fixed portions at points 13 and 14, respectively. Fixed at 15,16. Now extension 12b, 1
A line connecting 2c is defined as the Z axis, a line perpendicular to the Z axis and perpendicular to the surface formed by the coiled portion 12a is defined as the X axis, and a line perpendicular to the Z axis and the X axis is defined as the Y axis. The surface formed by the coil-shaped portion 12a is in the YZ plane, and the bobbin 11 can rotate about the axis Z as indicated by an arrow 17.

When polarized light is incident on the optical fiber 12 from the free end on the side of the point 13, the polarized light undergoes birefringence due to the bending of the coiled portion 12a when the polarized light passes through the coiled portion 12a, Therefore, the polarized light emitted from the free end portion of the optical fiber 12 at the point 14 has a polarization state changed from the polarization state at the time of incidence.

When the polarization state of the polarized light incident on the optical fiber 12 is changing, the bobbin 11 is rotated around the axis Z according to the change, so that the polarization mode is compensated for. It is possible to emit polarized light having a wave form.

“Problems to be Solved by the Invention” In the conventional optical fiber type optical polarization mode changing device shown in FIG. 1, the optical fiber 12 is fixed at points 13 and 14, and the bobbin 11 is rotated. Bobbin 11
The optical fiber 12 is twisted due to the rotation of the optical fiber 12, and if the rotational angle of the bobbin 11 increases in one direction, the optical fiber 12 becomes fatigued.
The optical fiber 12 may be cut off.

It is an object of the present invention to provide an optical fiber type optical polarization state changing device which stabilizes the characteristics of the device and which does not give any fatigue to the optical fiber even if the coiled portion is largely rotated.

[Means for Solving the Problems] According to the present invention, the optical fibers are extended in opposite directions on the same straight line in the coil plane from both ends of the coiled portion in which the optical fibers are bent. Both extension parts are fixed to the fixing part, respectively, and the coiled part is loosely sandwiched by the first and second side plates parallel to the coil surface.
The side plate is held so as to be rotatable about the extension of the optical fiber as an axis. In order to maintain this rotation, for example, at the positions of both extension portions of the optical fiber, one ends of the first and second pipes are fixed to the first and second side plates, respectively, and the first and second pipes are respectively fixed. The optical fiber extension portion is inserted, and the first and second pipes are rotatably held by the fixed portion.

When the first and second side plates are rotated, the coil portion is also rotated, so that the polarization state of the polarized light passing through this optical fiber is changed. In this case, in the present invention, since the coiled portion of the optical fiber is not wound around the bobbin but is held loosely by being sandwiched by the first and second side plates, the twist generated by the rotation of the coiled portion causes the optical fiber itself to rotate. Compensated by rotation about the heart, there is no risk of fiber optic disconnection.

Further, a support piece is provided between the first and second side plates, and the support piece supports the coil-shaped portion. With this configuration, the shape of the coiled portion can be kept stable, and the characteristics of the device can be made stable. or,
By configuring the optical fiber with a single-layer or multi-layer cushioning material, it is possible to prevent abrasion and characteristic deterioration of the optical fiber caused by contact with the first and second side plates.

"Embodiment" FIG. 2 shows a first embodiment of the present invention. Light fiber 12
Is wound in a coil shape to form a coil-shaped portion 12a, and the optical fiber is extended in a tangential direction opposite from one point of the coil-shaped portion 12a, and these extension portions 12b and 12c are fixed to the fixing portions 15 and 16 at points 13 and 14, respectively. Fixed. No bobbin is provided on the coil-shaped portion 12a, and the coil-shaped portion 12a is held by the side plates 21 and 22 which face each other so as to be loosely sandwiched. That is, the coiled portion 12a has a coil shape of one turn in this example,
The coil surface closely faces the side plates 21 and 22. Side plate 21,
The optical fiber 22 can rotate about the optical fiber extensions 12b and 12c as shown by the arrow 17, as shown by the arrow 17.

Due to such a structure, the side plates 21 and 22 are maintained in a parallel positional relationship with each other and the arrow 17 is formed around the extension portions 12b and 12c.
When rotated like this, the coil surface of the coil-shaped portion 12a of the optical fiber also rotates, and the polarization state of the polarized light passing through the optical fiber 12 is changed as in the conventional one shown in FIG.
Since the coiled portion 12a of the optical fiber is loosely inserted between the side plates 2122, the optical fiber 12 has its own axis centered in the direction of compensating for the twist of the optical fiber 12 that occurs in accordance with the rotation of the coiled portion 12a. It will automatically rotate to the center. Therefore, according to this optical fiber type polarization changing device, the side plate is
Even if 21,22 is rotated in one direction with a large rotation angle,
Light fiber 12 does not cause fatigue,
There is no danger of cutting.

FIG. 3 shows a second embodiment of the present invention, and parts corresponding to those in FIG. 2 are designated by the same reference numerals. In this embodiment, the pipes 23a, 23b are provided at the positions of the optical fiber extension parts 12b, 12c, and one ends of the pipes 23a, 23b are sandwiched by the side plates 21, 22 and fixed to each other, and extended to the pipes 23a, 23b. The parts 12b and 12c are respectively inserted. The pipes 23a and 23b are supporting plates 24 and 25 facing each other.
And is rotatably held. Support plates 24 and 25 are base 2
Standed on 6. On the base 26, the fixing portions 15 and 16 are provided so as to project outside each other of the pipes 23a and 23b, and the optical fiber extension portions 12b and 12c derived from the pipes 23a and 23b are arranged on the fixing portions 15 and 16. , The extended portions are fixed to the fixed portions 15 and 16 by presser pieces 15a and 16a which are attached to the fixed portions 15 and 16 so as to open and close, respectively.
It is clamped and fixed to 16.

It goes without saying that this embodiment can also obtain the same operational effect as that shown in FIG.

As shown in FIG. 4, the number of turns of the coiled portion 12a may be plural. Further, as shown in FIG. 5, a plurality of coil portions 12a and 12a 'may be provided. These coiled parts 12
The a and 12a 'are rotated around the extension parts 12b and 12c as the axes, and the coiled parts 12a and 12a' are connected at the approaching positions of the extension parts 12b and 12c.

As shown in FIG. 6, the optical fiber 12 may be coated with a single layer or multiple layers of buffer material 27. Since the optical fiber 12 is protected from friction with the side plates 21 and 22 by the buffer material coating 27, a stable and highly reliable device can be realized.
As shown in FIG. 7, a support piece 28 that is in contact with or close to the outer circumference of the coil-shaped portion 12a is provided between the side plates 21 and 22. Support piece 2
Further, the curved shape of the coil-shaped portion 12a of the optical fiber is stably supported, and a stable and highly reliable device can be realized. The support piece 28 may be provided between the side plates 21 and 22 so as to be in contact with or close to the entire outer periphery of the coil-shaped portion 12a, as shown by the diagonal lines in FIG. A circular hole is formed in the toe support piece 28 by cutting one side edge of the plate-shaped body, and the coil-shaped portion 12a is arranged in the circular hole. Support piece 2
As shown in FIG. 11, the side plates 21, 22 are
A disk-shaped member is arranged between them, and the coil-shaped portion 12a is arranged so as to wind the outer peripheral surface of the disk-shaped support piece 28. In this case, the coiled portion 12a is not tightly wound around the support piece 28 as much as friction is generated.

Further, the support pieces 28 shown in FIGS. 10 and 11 may be used in combination, and the coil-shaped portion 12a may be arranged in the circular passage formed between the two support pieces 28. 10 and 11 are the fifth
Although this is an example corresponding to the drawing, the same support piece 28 in FIGS. 10 and 11 may be used in the configurations of FIGS. 2 to 4. As shown in FIG. 8, a gear 29 is fixed on one pipe 23b, and a gear 31 meshing with the gear 29 is provided. By rotating the gear 31 by, for example, a motor, the side plates 21 and 22 are moved as shown by arrows 17. It can be rotated.
Instead of the gears 29, 31, it is possible to use a rotation transmission mechanism such as a pulley and a belt.

Although the extension parts 12b and 12c are derived from the same point of the coiled part 12a in the above, the extension parts 12b and 12c may be derived from two points of the coiled part 12a. An example thereof is shown in FIG. As shown in this figure, the extension portions 12b and 12c are extended positions 12b and 12c in opposite directions on the straight line from two intersection points of straight lines intersecting the coil portion 12a in the coil plane of the coil portion 12a. Is derived so that the side plates 21 and 22 can rotate about the extensions 12b and 12c as the axes.

As described above, according to the present invention, even if the coiled portion of the optical fiber is rotated in one direction with a large rotation angle, the optical fiber is not twisted. There is an advantage that an optical fiber type optical decentering state changing device that does not cause cutting can be realized easily and in a small size.

[Brief description of drawings]

FIG. 1 is a perspective view showing the principle of a conventional optical fiber type optical polarization mode changing device, FIGS. 2 to 6 are perspective views showing an embodiment of the device of the present invention, and FIG. 7 is a view of the device of the present invention. Front view showing another example, FIG. 8 and FIG. 9 are perspective views showing still another example of the device of the present invention, and FIG. 10 and FIG. 11 are further examples of the device of the present invention, especially a support piece. It is a front view which shows the modification. 12: optical fiber, 12a: coiled part of optical fiber 12, 12b, 1
2c: extension of the optical fiber 12, 13, 14: position on the optical fiber 12, 15, 16: fixed part, 21, 22: side plate, 23a, 23b: pipe.

Continuation of front page (56) References JP-A-56-52703 (JP, A) Electronics Letters Vol. 16, No. 20, PP. 778-780

Claims (1)

[Claims] 1. A first and a second pipe which are fixed at one end of first and second pipes having a common axis and are arranged so as to have a distance equal to or larger than an inner diameter of these pipes. A side plate, a coil-shaped portion composed of a coil-shaped optical fiber that is loosely sandwiched between the first and second side plates, and optical fibers at both ends of the coil-shaped portion that penetrate the first and second pipes. As described above, the first and second extension portions extending in substantially the same straight line in opposite directions, the fixing portion for fixing the optical fiber in the first and second extension portions, and the first and second extension portions. A support piece that is provided between the second side plates and that is in contact with the coil-shaped portion and keeps the coil shape; and the first and second pipes and the first and second pipes.
An optical fiber type optical polarization mode changing device, characterized in that the side plates of the device are integrally rotatable with respect to the axis.