JP2620321B2 - Light switch - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch, and more particularly, to a so-called 1 × N optical switch that switches and connects one optical fiber and a plurality of optical fibers. And an optical switch for mechanically performing switching.

(Prior art)

Various 1 × N switches are conceivable, and the followings have been studied and realized in the optical axis alignment of the switching optical fibers.

For example, a paper entitled “High-density 1 × 1000 optical switch using ceramic ferrule” presented by Sugimoto et al. , A paper entitled “Large-scale low-loss 1 × N optical switch” presented by Furukawa et al. At the 70th Anniversary National Convention and a presentation by Kojima et al. In addition, there is an article shown in a paper or the like entitled "Result of 30,000 times of detachable test of connector switching type optical switch". In the 1 × N optical switch shown in these articles, ferrules, which are components of an optical connector, are arranged two-dimensionally or one-dimensionally.
It is attached to a device that moves the opposing ferrule two-dimensionally or one-dimensionally. Then, an optical fiber is connected to a ferrule arranged two-dimensionally or one-dimensionally, and an optical fiber is also connected to a ferrule that is moved on one side.
The ferrules are selectively connected to the arranged ferrules to switch the optical fiber transmission lines.

As another example, there is a switch of a type that drives a prism by electromagnetic force and switches a transmission path of light propagating through the prism, such as an optical channel selector manufactured by Anritsu Corporation as a communication measuring instrument. .

Further, "Letters Cascaded for Multimode Optical Fibers for Single-mode and Multi-mode Optical Fibers" published by A.W., C.I., and Young on page 571 of Vol. 17, No. 16, August 6, 1981, Electronics Letter, Electron
ics Letters 6th August, 1981, Vol. 17, No. 16 page 571,
“CASCADED MULTIPOLE SWITCHES FOR SINGLE-MODE AND
MULTIMODE OPTICAL FIBER "WCYOUNG" shows a mechanically driven optical switch.

[Problem to be solved by the invention]

However, in the 1 × N optical switch in which the ferrules described in the above document are arranged two-dimensionally or one-dimensionally, as the number of switching cores increases, the size of the arrangement part arranged two-dimensionally or the like increases. However, the entire device becomes too large. Therefore, the number of switching hearts cannot be increased. Also, in this type of 1 × N optical switch, the optical axes of the optical fibers to be connected are aligned with each other.
Since the optical connector uses the outer diameter alignment of the ferrule, which is a component, the outer diameter of the ferrule is worn when the ferrules are connected to each other. Therefore, the number of repetitive switching is limited, and there is a problem in long-term reliability and durability. In addition, dust is generated due to the abrasion and may adhere to the end face of the optical fiber in the ferrule. In such a case, the connection loss increases. Furthermore, when applying the method of switching connection of the optical fiber itself using spatial connection to an optical switch in which optical fibers are two-dimensionally arranged, a high-precision positioning device has been required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical switch which solves the above-mentioned problems and has high reliability and durability against repetitive switching, and enables accurate optical axis alignment of optical fibers to be connected. .

[Means for solving the problem]

An optical switch according to the present invention includes a first switch in which a light source is connected to one end.
An optical fiber, one end of which is opposed to the other end of the first optical fiber by a predetermined distance, and a second optical fiber whose optical axis is aligned with the first optical fiber;
An optical path switching means which is inserted with a predetermined gap into a space between the first and second optical fibers and is movable on a plane perpendicular to the optical axis direction of the first and second optical fibers; Facing the end face of the optical fiber, and extending in parallel with the optical axis of the first optical fiber in the vicinity of the facing portion;
A third optical fiber of which the opposing portion is fixed in the optical path switching means, and an optical axis of the second optical fiber which opposes the end face of the second optical fiber on the side of the separated portion, and near the opposing portion; And the optical axis near the facing portion of the third optical fiber coincides with the optical axis near the facing portion of the third optical fiber, and the facing portion is fixed in the optical signal switching means. An optical fiber, moving means for moving the optical path switching means on a plane perpendicular to the optical axis direction of the first and second optical fibers, and an end opposite to the third optical fiber and the facing part The optical output from the optical fiber is detected, the moving means is controlled so that the optical output becomes maximum, the optical signal switching means is moved, and the facing portion between the first optical fiber and the third optical fiber is controlled. Optical path switching by performing optical axis alignment with Characterized in that it comprises a control means for axial alignment of the optical axis between the fourth of said second optical fiber and the optical axis of the optical fiber at the opposite end of the unit.

[Action]

Since the optical switch of the present invention is configured as described above, there is no contact portion when switching the optical switch. Also, when switching the optical switch, the axis alignment is performed using feedback control, thereby always enabling accurate axis alignment.

〔Example〕

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

FIG. 1 is a partially exploded perspective view of an embodiment of an optical switch according to the present invention.

As shown in the figure, the optical switch 1 includes an optical fiber holding unit 10 for holding a plurality of optical fibers, an optical path switching member 20 for switching optical paths, a moving mechanism 30 for moving the optical path switching member 20, and a moving mechanism 30. And a control mechanism 40 for controlling the

FIG. 2 is a perspective view of the optical fiber holding unit 10. In this figure, the optical fiber holding section shown in FIG. 1 is shown upside down. As shown in the figure, a plurality of optical fibers 11 are arranged in an optical fiber holding portion 10 in a V-shaped groove 13 on a two-stage silicon plate 12 in parallel at a pitch of P = 0.25 mm, for example. A groove 14 that crosses the optical fiber 11 is formed at the center. The apex angle of the V-groove 13 is 60 degrees, and its depth is set so that an optical fiber having an outer diameter of 125 μm can be inserted. on the other hand,
The groove 14 has a width l1 = 5 mm and a depth d2 = 0.2 mm, and is formed at a depth at which at least the core of the optical fiber 11 fixed in the silicon substrate 12 is exposed. And this groove 14
Are inclined about 5 degrees (.theta.) With respect to the direction perpendicular to the optical axis of the optical fiber 11, as shown in FIG. This is to prevent the reflection of light on the side surface of the optical path switching member 20. Further, the optical fiber 11 is divided into two parts by the groove 14. One optical fiber divided by groove 14
After the side opposite to the groove 14 side of 11a and the end 11c are bundled into one,
It is optically coupled to a light source 15. Groove 1 of the other optical fiber 11b
An end 11d opposite to the fourth side is a signal input / output side of this optical switch. In this embodiment, a halogen lamp is used as the light source 15, and the optical fiber 11 is an optical fiber normally used for communication, and has a finished outer diameter of 250 μm. It was used. The characteristics and structure of this optical fiber
= 10 μm ± 1 μm, cutoff wavelength 1.2 ± 1 μm, cladding outer diameter 125 μm, and relative refractive index difference 0.3%.

FIG. 3 is a perspective view of the optical path switching member 20. As shown in this figure, the optical path switching member 20 has a substantially rectangular parallelepiped shape, and the upper part thereof can move spatially in the groove 14. The side surface 21 is inclined by θ = 5 degrees along the inner surface of the groove 14 described above. Further, two optical fibers 22, 23 are fixed to the optical path switching member 20. The respective ends 22a, 22a of these optical fibers 22, 23 are located on the inclined side surface, and near the side surface, these optical fibers
The optical axes of 22 and 23 are on a straight line as shown by a dashed line in the figure. Further, in the optical axis direction, the optical path switching member 20 is
And a direction perpendicular to the direction X of sliding inside. The other end 22b of the optical fiber 22 is engaged with a light receiving element such as a photodiode, and an optical signal is input from the other end 23b of the optical fiber 23. FIG. 4 shows a positional relationship between the groove 14 and the optical path switching member 20 as viewed from the moving direction X of the optical path switching member 20. As shown in the figure, the optical path switching members 20 are spatially arranged with respect to the grooves 14, and these grooves 14 and the optical path switching members
The gap with 20 is d1 = about 50 μm. This gap is
When the optical path switching member 20 is moved, the optical fibers 11a and 11b fixed in the optical fiber holding unit 10 are fixed to the ends 11c and 11d of the optical fibers 11a and 11b and the optical path switching member 20 without contacting the inner surface of the groove 14. It must be selected so that the optical transmission loss between the ends 22a and 23b of the optical fibers 22 and 23 is not so large.

The moving mechanism 30 includes a pulse motor 31 and this pulse motor
The ball screw 32 is connected to a rotation shaft of the ball screw 31, and the stage 33 moves in the longitudinal direction of the ball screw 32 by the rotation of the ball screw 32. The side of the ball screw 32 opposite to the side connected to the pulse motor 31 is supported by a bearing 34. Further, as shown in the figure, a piezoelectric element 3 deforming in the X direction and the Z direction
5, 36 are installed. Further, the optical path switching member 20 is mounted and fixed on the piezoelectric elements 35 and 36. These piezoelectric elements 35 and 36 are deformed according to the direction and magnitude of the applied voltage. In this embodiment, it is configured to be slightly deformed in the X and Z directions shown in FIG. The amount of deformation is about 30 μm, and fine adjustment can be made according to the magnitude of the applied voltage. On the other hand, in the combination of the pulse motor 31 and the ball screw 32, a coarse movement operation at an interval of about 0.25 mm can be performed. By combining these coarse adjustment and fine adjustment, the optical fiber 11a and the optical fiber 2
An accurate optical axis alignment between the two can be performed.

The control mechanism 40 receives a light signal from a piezoelectric element controller 41 for controlling the piezoelectric elements 35 and 36, a pulse motor controller 42 for controlling the pulse motor 31, and an optical fiber 22, and generates an electric signal corresponding to the light intensity. A light receiving element 43 for outputting a signal, a power meter 44 for outputting a current corresponding to the intensity of the signal from the light receiving element 43, and an overall controller for inputting signals from the controllers 41 and 42 and the power meter 44
It consists of 45. In this embodiment, a light meter integrating a light receiving element 43 and a power meter 44 and incorporating a silicon-based photodiode was used, and a commercially available small computer of model HP9816 was used as the whole controller 45.

Next, a method of manufacturing the optical fiber holding unit 10 and the optical path switching member 20, which are one of the components of the present embodiment, will be described.

The optical fiber holding section 10 has a 2
An outer diameter of 12 with a vertical angle of 60 degrees
V-grooves 13 into which 5 μm optical fibers enter are formed in parallel at a pitch of 0.25 mm. Next, the optical fiber 11 is inserted into the V-groove 13 as shown in FIG. 5B and fixed with an adhesive or the like. Next, as shown in FIG. 5C, a groove 14 having a trapezoidal cross section as shown in FIG. 4 is formed at the center of the step portion. The depth of the groove is such that at least the core of the fixed optical fiber 11 is exposed.

Even if the optical fiber is inserted and fixed in the V-groove, the optical fiber is not necessarily fixed to the side surface of the V-groove as shown in FIG.
It is difficult to position accurately, and it is difficult to align the optical axes of two optical fibers. Further, the eccentricity of the outer diameter of the inserted optical fiber is not always the same. However, by dividing one optical fiber by a groove and forming two optical fibers, the end faces of the optical fibers facing each other with the groove interposed between the groove, the outer diameter of the optical fiber, and the eccentricity are almost the same. Can be considered a match. Therefore, it can be considered that the positions of the optical fibers facing each other with the groove interposed therebetween coincide with the cut surface.

Focusing on these points, the optical fiber holding unit 10 was manufactured by the manufacturing method described above.

In the manufacture of the optical path switching member 20, grooves are formed in a straight line in a substantially rectangular silicon base material. The optical fibers 22 and 23 are inserted so that the end faces are respectively located at both ends of the groove, and are fixed with an adhesive resin or the like. Then, the optical fiber 2 fixed with resin
Process silicon substrate and adhesive resin together with 2, 23
It is formed in a shape as shown in the figure. Where the optical fiber 22,
Since the end faces of 23 are inserted and fixed in grooves formed in a straight line, the optical axes of the end faces are on a straight line, and the optical axes coincide with each other.

Next, the operation principle of this embodiment will be described with reference to FIGS.
This will be described with reference to the drawings.

First, a pulse motor control signal is transmitted from the overall controller 45 to the pulse motor controller 42 in response to a switch selection signal input from outside. In response to the pulse motor control signal, the pulse motor controller 42 drives the pulse motor 31, moves the stage 33, and moves the optical path switching member 2 to the center position of the optical fiber 11b according to the switch selection signal.
The end face 23a of the 0 optical fiber 23 is made to come. And
The pulse motor 31 can stop the stage 33 at an arrangement pitch P = 0.25 mm of the optical fibers 11a and 11b. However, accurate positioning cannot be performed by the movement of the pulse motor 31, and the pulse motor 31 is in a coarse movement state. In this coarse movement state, the optical path switching member reaches the center position of the corresponding optical fiber.
Move 20. Next, fine position adjustment is performed using the piezoelectric elements 35 and 36. In this fine adjustment, the light emitted from the light source 15 is received by the light receiving element 43 via the optical fiber 11a and the optical fiber 22, and the received light intensity is detected by the power meter 44. Then, the piezoelectric controller 41 is operated by the overall controller 45 to drive the piezoelectric elements 35 and 36 so that the output of the power meter 44 becomes maximum. Here, the piezoelectric element 3
5, 36 can finely adjust the optical path switching member 20 mounted thereon in the X and Z directions. At the position of the optical path switching member 20 at which the received light intensity obtained in this way is maximum, the portion of the optical fiber 22 facing the optical fiber 11a is
And the optical axis of the optical fiber 11a coincide with each other. On the other hand, the optical axis of the portion of the optical fiber 22 facing the optical fiber 11a coincides with the optical axis of the portion of the optical fiber 23 facing the optical fiber 11b. Furthermore, the optical axis of the optical fiber 11a matches the optical axis of the optical fiber 11b. Therefore,
When the optical fiber 22 and the optical fiber 11a are aligned with the optical axis, the optical fiber 23 and the optical fiber 11b are aligned with the optical axis, and the optical signal incident from the end 23b of the optical fiber 23 is selected. Transmitted to the optical fiber 11b with low transmission loss. In addition, since the optical axis alignment state is adjusted using feedback control every time the switch is switched, accurate optical axis alignment is possible even if the optical fiber arrangement is deformed due to temperature changes applied to the entire switch. Become.

Therefore, in this embodiment, switching can be performed while always detecting the optical axis alignment state.

A 1 × 500 optical switch was prototyped according to the above embodiment, and a backscattering loss measuring system as shown in FIG. 7A was constructed to measure the connection loss. In this measurement system, the OTDR and the optical switch were connected by a 1 km optical fiber and connected via a splice. Further, a 100 m 10-fiber tape-shaped optical fiber is connected to the 500 output terminal on the output side of the optical switch for 100 m. And as a result of measurement using such a measurement system,
Average connection loss, αi = 1.2 dB or its standard deviation, α
As a result, n = 0.3 dB and the connection time per fiber was 20 seconds.

The present invention is not limited to the above embodiment, and various modifications can be considered.

Specifically, in the above embodiment, a 1 × N optical switch has been described. However, a 1 × 1 optical switch for simply turning on / off an optical signal is described.
It may be applied to an optical switch.

Further, in the above embodiment, the moving mechanism of the optical path switching member is performed by combining the pulse motor and the piezoelectric element. However, the moving mechanism is not limited to this, and may be performed by using, for example, an ultrasonic motor.

In the above embodiment, the manufacturing method of the optical fiber holding section and the optical path switching member is described. However, the manufacturing method is not limited to this, and any method may be used as long as the optical axes of the optical fibers coincide with each other. Method may be used.

〔The invention's effect〕

As described above, in the optical switch of the present invention, there is no contact on the end faces of the optical fibers to be optically coupled, and the axis can be aligned while maintaining a predetermined interval. A high optical switch can be realized. Furthermore, since the axis alignment is performed using feedback control at the time of optical axis alignment, an optical switch having stable characteristics against changes in the surrounding environment due to heat or the like can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially exploded perspective view of an optical switch according to an embodiment of the present invention, FIG. 2 is a perspective view of an optical fiber holding portion of the optical switch shown in FIG. 1, and FIG. FIG. 4 is a perspective view of an optical path switching member of the optical switch shown in FIG. 1, FIG. 4 is a view showing a positional relationship between the optical path switching member and the groove, and FIG. FIG. 6 is a diagram showing a position state of the optical fiber in the V-groove, and FIG. 7 is a diagram showing a measurement system of the optical switch according to the embodiment of the present invention. 1 ... optical switch, 10 ... optical fiber holder, 11, 11
a, 11b, 22, 23 ... optical fiber, 20 ... optical path switching member, 30 ... moving mechanism, 31 ... pulse motor, 35, 36 ...
Piezoelectric element, 40 Control mechanism.

Claims (4)

(57) [Claims] A first optical fiber having one end connected to a light source, one end of which is opposed to the other end of the first optical fiber by a predetermined distance; A second optical fiber whose axes are aligned, a plane perpendicular to the optical axis direction of the first and second optical fibers, which is inserted with a predetermined gap into a space between the first and second optical fibers; An optical path switching means movable on the upper side, facing the end face of the first optical fiber, and extending parallel to the optical axis of the first optical fiber in the vicinity of the facing portion, A third optical fiber to which an opposing portion is fixed, opposing the end face of the second optical fiber on the side of the separated portion, and extending near the opposing portion in parallel to the optical axis of the second optical fiber; The optical axis near the facing portion is in front of the third optical fiber. A fourth optical fiber which coincides with the optical axis near the facing portion and whose facing portion is fixed in the optical signal switching means; and wherein the optical path switching means is an optical axis of the first and second optical fibers. Moving means for moving on a plane perpendicular to the direction, detecting light output from an end of the third optical fiber opposite to the facing part, and controlling the moving means so that the light output is maximized. Then, the optical signal switching means is moved, and the optical axis of the first optical fiber and the opposing part of the third optical fiber are aligned, whereby the optical path switching means at the opposing part of the optical path switching means is moved. 4. An optical switch, comprising: control means for aligning the optical axis of the optical fiber with the optical axis of the second optical fiber. 2. The optical switch according to claim 1, wherein a plurality of said first and second optical fibers are provided, each of which is inserted and fixed in a V-groove formed parallel to each other. 3. The optical switch according to claim 1, wherein each of the first and second optical fibers is formed by cutting an intermediate portion of one optical fiber. 4. The optical switch according to claim 1, wherein said moving means comprises a pulse motor and a piezoelectric element.