JP3382209B2 - Fiber type optical switch - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber type optical switch used in the field of optical communication.

[0002]

2. Description of the Related Art An optical switch has a structure in which an optical path is switched by using a movable yoke position of a magnetic circuit.
No. 268212 discloses one.

In that publication, the positioning pin and the trapezoidal groove for positioning are mechanisms for positioning the movable optical fiber holding member with respect to the fixed optical fiber fixing member. An actuator for moving the movable optical fiber holding member is fixed to the substrate. It is described that the actuator is composed of a coil and a permanent magnet, and the movable optical fiber holding member is displaced by alternately attracting the soft magnetic member fixed to the movable optical fiber holding member.

[0004]

The structure in which a trapezoidal groove is used for positioning with a positioning pin is an excellent structure for realizing an optical switch with a small insertion loss. However, it is necessary to accurately process all four surfaces forming the trapezoidal groove for positioning, which causes an increase in manufacturing cost.

Further, in some cases, even if all four surfaces constituting the positioning trapezoidal groove are accurately processed, there is a problem that the optical fiber is misaligned at the time of switching.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical switch which is excellent in mass productivity and has reduced optical coupling loss.

[0007]

As a result of intensive studies to solve the above problems, the inventor of the present invention has found a mechanism for generating a positional deviation of optical fibers at the time of switching, and has reached the present invention.

For example, for the above-mentioned purpose, the first block (movable fiber holding block) to which the end of the first optical fiber is fixed and the second block (fiber holding block) to which the end of the second optical fiber is fixed. In a fiber type optical switch that is provided facing each other and switches the optical path by relatively moving the first block with respect to the second block, a block moving means for moving the first block by magnetic force, A pair of grooves formed in the first block, a pair of guide pins having one end inserted into the groove and the other end fixed to the second block, and the first to cover the groove. And a pressing plate disposed in the block, the pair of grooves are formed in a direction along the longitudinal direction of the first optical fiber with the first optical fiber interposed therebetween. The guide pin is dimensioned in the depth direction of the groove has a smaller cross section than the depth of the groove, is solved by further comprising a configuration requirements below.

(1): The first block is a soft magnetic material, one of the guide pins contacts the side wall of the groove near the first fiber side and the pressing plate, and the other of the guide pins. The widths of the pair of grooves are configured such that the contacting portion contacts only the pressing plate.

(2): The pressing plate is a soft magnetic material,
The width of the pair of grooves is configured such that one of the guide pins contacts the side wall of the groove farther to the first fiber side and the pressing plate, and the other of the guide pins contacts only the pressing plate. Was it.

According to this structure, the number of positioning walls and surfaces that require precision processing can be minimized, and the displacement of the optical fiber at the time of switching can be prevented. The positioning mechanism for aligning the optical axes of the fiber and the second fiber with high accuracy can be achieved at low cost.

[0012]

1 is a top view showing the overall structure of an optical switch according to an embodiment of the present invention. Optical fiber 10
2 is the base 10 by the fiber holding block 103.
It is fixed at 4. The end of the optical fiber 102 to which the input optical signal 101 is input is fixed to a movable fiber holding block 106 made of soft magnetic ceramics having a movable structure. An end of a highly rigid guide pin 105 is slidably inserted into a groove formed in the movable fiber holding block 106. The other end of the guide pin 105 is fixed to a fiber holding block 107 made of soft magnetic ceramics. The movable area of the movable fiber holding block 106 is defined by the width of the groove described above by the guide pin 105.

An optical fiber 110 is fixed to the fiber holding block 107, and an output optical signal 111a or 111b is output from the optical fiber 110. The movable fiber holding block 106 is sandwiched by the yoke 109 while ensuring a swinging space. A permanent magnet 112 is magnetically connected to the yoke 109, and further, coils 108a and 108b are wound around the yoke 109. These parts are joined to the base 104,
The base 104 is bonded to or integrally formed with the package base 100.

When the movable fiber holding block 106 is on the side of the coil 108a as shown by the solid line, the optical fiber 102 is coupled to the first and third optical fibers 110 from the top. As a result, the input optical signal 101 is output from the present optical switch as the output optical signal 111a. Movable fiber holding block 106
Is continuously held at the position indicated by the solid line by the magnetic force of the permanent magnet 112 acting through the yoke 109.

Here, the coil 108 is supplied from a power source (not shown).
A current is applied to a in a direction that weakens the magnetic flux in the yoke 109,
On the other hand, when a current is made to flow through the coil 108b in the direction of strengthening the magnetic flux in the yoke 109, the movable fiber holding block 106 is attracted to the coil 108b side and switched to the position shown by the broken line. Once switched, the permanent magnet 1 works through the yoke 109 even if the current is cut off.
The magnetic force of 12 keeps it held at the position indicated by the broken line. At this time, the optical fiber 102 is coupled to the second and fourth optical fibers from the top among the optical fibers 110.
As a result, the input optical signal 101 is output from the present optical switch as the output optical signal 111b.

Further, if the direction of the current is reversed again and the currents are respectively applied to the coils 108a and 108b, the movable fiber holding block 106 is attracted to the coil 108a side and switched to the position shown by the solid line and held. As described above, in the present optical switch, the path of light can be switched by changing the direction of the current flowing through the coils 108a and 108b.

In the present embodiment, the optical signal is input from the fiber holding block 103 side and output from the fiber holding block 107 side. On the contrary, the optical signal is input from the fiber holding block 107 side. Even when input and output from the fiber holding block 103 side, switching of optical signals can be performed in exactly the same manner.

Next, the optical switching principle of the optical switch will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the cross-sectional structure of the light switching portion (movable fiber holding block) of the optical switch.

The guide pins 105a and 105b are provided in the groove 20.
2a and 202b, the upper opening of the groove is covered with a pressing plate 201, and the cross section of the guide pin movable region perpendicular to the axis of the guide pin 105 has a quadrilateral shape close to a trapezoid. The movable fiber holding block 106 includes
A force N acts in the arrow directions 203 and 204.

The movable fiber holding block 106 includes:
Groove 2 sized so that the guide pins 105a and 105b can move
02a and 202b are formed. Guide pins 105a and 105b are inserted into the respective grooves.
The movable fiber holding block 106 is the guide pin 105.
By moving left and right on the paper with respect to a and 105b,
The movable fiber holding block 106 is positioned.
The optical fiber 102 is a movable fiber holding block 10.
Since it is fixed and held in the V groove provided in 6, the position of the tip of the optical fiber 102 can be switched by moving the movable fiber holding block 106.

However, in FIG. 2, in order to facilitate understanding of the operation, the position of the movable fiber holding block 106 is fixed and the position is displayed as if the guide pins 105a and 105b have moved. Actually, as described above, the movable fiber block 106 moves without moving the guide pins 105a and 105b.

The switching force N acts as indicated by an arrow 203 so that the movable fiber holding block 106 is guided by the guide pin 1.
When moving to the right with respect to 05a and 105b, the guide pin 10 for the movable fiber holding block 106
The positions of 5a and 105b are as shown by the solid line. As a result, the guide pin 105a is provided on the side wall of the groove 202a farther from the optical fiber 102 (hereinafter referred to as the outer wall).
The position of the guide pin 105b is determined by contacting a side wall (hereinafter referred to as an inner side wall) of the groove 202b near the optical fiber 102.

On the contrary, the switching force N is indicated by the arrow 204.
When it acts as described above, the movable fiber holding block 106 moves to the left with respect to the guide pins 105a and 105b. Thereby, the guide pins 105a, 105
The position of b is as shown by the dotted line. That is, the guide pin 105a is attached to the inner wall of the groove 202a by the guide pin 1a.
05b comes into contact with the outer wall of the groove 202b to be positioned.

Therefore, in order to improve the switching accuracy of the optical fiber 102, the processing accuracy of the grooves 202a and 202b of the movable fiber holding block 106 and the guide pin 105a,
It is necessary that the positional accuracy of 105b is extremely high. For example, the coupling loss of light due to the displacement in the translation direction is 1 dB.
In order to achieve the following, it is necessary to suppress the dimensional accuracy of each surface of the grooves 202a and 202b to 2.5 μm or less.

FIG. 3 is a cross-sectional view showing the mechanism of displacement occurring at the time of switching. In the figure, arrow 301 indicates the direction of rotation.

The movable fiber holding block 106 includes:
The switching force N acts as indicated by an arrow 203. The guide pins 105a and 105b are located on the left side of the movable fiber holding block 106. However, although the guide pin 105a is in contact with the inner wall of the groove 202a,
The guide pin 105b is not in contact with the inner wall of the groove 202b. Therefore, the movable fiber holding block 106 is
Rotational movement is possible with the center O of the guide pin 105a as the axis of rotation.

Here, the switching force N acts as shown by an arrow 203. The distance between the line of action of the switching force N and the center of the guide pin 105a is h. Guide pin 105
A rotation moment M = h · N that acts to rotate the movable fiber holding block 106 around the center of the guide pin 105a as a rotation axis acts around a. That is, the rotation moment M acts in the direction of rotating the movable fiber holding block 106 counterclockwise on the paper surface, and the movable fiber holding block 106 rotates. However, when the guide pin 105b contacts the bottom surface of the groove 202b, the movable fiber holding block 106 cannot rotate any more.
Therefore, the movable fiber holding block 106 will be held in the rotated position shown by the dotted line.

With this rotational movement, the optical fiber 102 also moves and deviates from the normal optical coupling position. This causes a decrease in optical coupling efficiency. That is, when the processing accuracy of the groove 202 of the movable fiber holding block 106 is poor, the movable fiber holding block 106 is accompanied by the switching.
In addition to the translational motion error of (1), the positional displacement due to the rotational motion may occur, and the optical fiber 102 may not be accurately positioned. Therefore, in order to reduce the optical coupling loss, it is necessary to process all the surfaces of the grooves 202a and 202b with high accuracy.

FIG. 4 is a sectional view showing the dimensional relationship of the contact portion between the guide pin and the groove. Guide pin 105 and groove 20
2, only one side of FIG. 2 or FIG. 3 is shown. Moreover, the state where the movable fiber holding block 106 is close to one side is shown.

A point on the side wall at a position of depth r from the upper surface of the block (a surface on which the pressing plate is provided to cover the groove 202) is A, a contact point between the guide pin and the side wall is B, and a center of the guide pin is the center. The radius of O and the guide pin is r. When the triangle ABO is formed by these three points, the vertex B is a right angle, and therefore the following equation holds. cos θ = r / [OA] where [OA] is the length of the side OA. Letting C be the intersection of the side OA and the guide pin outer periphery, [OA] = r + [CA]. Therefore, the following equation holds. [OA] = r + [CA] = r / cos θ Therefore, [CA] = (1 / cos θ−1) r.

Since the other side wall of the groove has an inclination of φ, the distance between the side wall of the guide pin and the side wall indicated by the broken line at the point of depth r from the block upper surface is given by the following equation. (1 / cos -1) r Next, the relationship between the switching stroke and the groove size of the optical switch of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view including a fiber holding block having a movable structure and a guide pin in a direction perpendicular to a light traveling direction.

Reference numeral 501 is a circle having a radius r (corresponding to the guide pin 105) whose center is located at a position r from the upper surface of the block and is in contact with the outer wall of the pressing plate 201 and the groove 202a.

The movable fiber holding block 106 includes:
Grooves 202a and 202b are formed, and the guide pins 105a and 10b are provided in the respective grooves 202a and 202b.
5b is inserted. A pressing plate 201 is joined to the upper surfaces of the grooves 202a and 202b so as to cover it.

In the plane of depth r from the block upper surface,
In the figure, the distance between the inner wall of the left groove 202a and the right groove 202b is a, the distance between the inner and outer walls of the left groove 202a is d1, and the distance between the inner and outer walls of the right groove 202b is d2.
And Further, the movable fiber holding block 106 is switched to the right side with respect to the guide pin, and the guide pin 10
5b and the inner wall of the right groove 202b are in contact with each other, the distance between the outer wall of the left groove 202a and the outer periphery of the guide pin 105a is c1, and the inner wall of the right groove 202b and the guide pin 10 are formed.
Let b2 be the distance from the outer periphery of 5b. Further, with the movable fiber holding block 106 switched to the left side with respect to the guide pin, the guide pin 105a and the left groove 202 are
With the inner wall of a contacting as shown by the broken line, the groove 2 on the left side
The distance between the inner wall of 02a and the outer circumference of the guide pin 105a is set to b.
1, the outer sidewall of the right groove 202b and the guide pin 105
The distance from the outer circumference of b is c2.

Now, the block is switched to the right side, and the right guide pin and the inner wall of the right groove 202b are
It is assumed that they are in contact with each other as shown by the solid line. At this time, the distance c1 between the left guide pin 105a and the outer wall of the left groove 202a is as follows. c1 = (r + b2 + a + d1)-(a + b1 + b2 + 2r
+ P) -r = d1-b1-2r-P where the outer wall of the left groove 202a and the guide pin 105a
If there is no contact, the movable fiber holding block 106
Is the center Q of the guide pin 105b. Therefore, the movable fiber holding block 106 is acted on by the moment M ′ that causes it to rotate counterclockwise on the paper surface. However, the movable fiber holding block 106 cannot rotate because the positioning pin 105a that is already in contact with the pressing plate 201 restrains this rotational movement. This prevents the optical fiber from being displaced due to the rotational movement of the fiber holding block 106.

That is, the fiber holding block 106
It can be seen that the condition in which the positioning guide pin 105a does not come into contact with the outer wall of the groove 202a in the state where is switched to the right side is a condition for preventing the rotational movement of the movable fiber holding block 106.

In other words, the guide pins 105a, 10
The center-to-center distance D of 5b is constant. Therefore, for example, when the movable fiber holding block 106 is moved to the maximum in the fiber positioning direction and the two states in which the guide pin 105 is brought into contact with one side wall and the pressing plate 201 to be positioned are drawn in an overlapping manner, Guide pin 105
When the center-to-center distance between a and 105b is a ', the movable range of the movable fiber holding block 106 is D-a', and at this time, the groove width Dm (= m at the depth r from the groove side surface of the pressing plate 201). By forming d1 and = d2) so as to have a relationship of Dm> D−a (where φ1 = φ2 = θ1 = θ2), the above-described effect can be obtained. That is, when one of the guide pins comes into contact with the inner wall of the groove of the movable fiber holding block and the holding plate, the other guide pin does not come into contact with the inner wall of the paired groove but only the holding plate. The groove width is set.

Here, when the outer wall of the left groove 202a is in contact with the circle 501 having a radius r whose center shown by the chain double-dashed line is at a position r from the top surface of the block, the distance between the side wall and the circle Be e1. If c1 is larger than e1, the left guide pin 105a and the outer wall of the groove 202a do not contact each other. That is, the relationship is c1> e1.

Therefore, d1-b1-2r-P> e1 and e1 = (1 / cos φ1-1) r, b1 =
Substituting (1 / cos θ1-1) r and rearranging, the following equation is obtained. d1> 2r + P + (1 / cos θ1-1) r + (1 / cosφ1-1) r (Equation 1) Therefore, the dimensions of the block in which the groove in which the guide pin slides are formed satisfy Equation 1. In this case, the switching operation is performed with high accuracy.

The outer wall of the right groove 202b and the guide pin 10
Regarding the positional relationship of 5b as well, when the following expression is similarly satisfied, the guide pin 105b and the outer wall of the groove 202b do not come into contact with each other, and high precision switching is realized. When the outer wall of the right groove 202a is in contact with a circle (not shown) having a radius r at a position r from the block upper surface, the distance between the outer wall and the circle is e2, then c2> e2,
Therefore, d2-b2-2r-P> e2. To this, e2
= (1 / cos φ2-1) r, b2 = (1 / cos θ2
-1) Substitute r to obtain the following equation. d2> 2r + P + (1 / cos θ2-1) r + (1 / cosφ2-1) r (Equation 2) In this embodiment, the block in which the groove is formed is the soft magnetic material. In contrast to this, when the pressing plate is a soft magnetic material, the direction of the rotational moment generated by the action of the switching force is opposite. In this case, as the condition for high-precision switching, the following equation is obtained in the same manner as in the case where the block in which the groove is formed is the soft magnetic material. d1 <2r + P + (1 / cos θ1-1) r + (1 / cosφ1-1) r (Equation 3) d2 <2r + P + (1 / cosθ2-1) r + (1 / cosφ2-1) r (Equation 4) FIG. 6 shows an example of specific dimensions in the configuration of FIG.

At a position 0.125 mm from the upper surface of the movable fiber holding block 106, the width of the grooves 202a and 202b is 0.5964 mm, and the angle formed by the perpendicular to the upper surface of the movable fiber holding block and the inner and outer walls of the grooves 202a and 202b. The radius r of the guide pins 105a and 105b is 32.5 degrees and is 0.125 mm.

When the guide pin 105a and the groove 202a are in contact with each other as shown by the broken line, the outer periphery of the guide pin and the groove 20.
The distance from the inner wall of 2a is 0.0232 mm by substituting θ = 32.5 degrees and r = 0.125 mm at (1 / cos θ−1) r. The switching stroke is 0.250 mm. From these values, the left side of equations 1 and 2 is 0.5964 mm, and the right side is 0.5464 mm. Therefore, the left side is larger than the right side and satisfies equations 1 and 2.

With the structure shown in FIG. 6, the grooves 202a, 2a
The machining error of the outer wall of 02b is 50 μm, and the machining error of the bottom is
Even if it is as large as 30 μm, it is possible to construct an optical switch in which the optical coupling loss due to the displacement of the optical fiber in the translational direction is 1 dB or less. Therefore, the movable fiber holding block 106
Can be easily processed and the manufacturing cost can be reduced.

Further, in this embodiment, the grooves 202a, 20a
Although the angle of the outer wall of 2b is set to 32.5 degrees, if this is set to 0 degrees, the groove may be machined vertically from the upper surface of the movable fiber holding block 106. In this case, since the outer wall of the grooves 202a and 202b can be efficiently processed by using a tool having a flat tip and a wide width, it is possible to further reduce the manufacturing cost.

An example of the overall configuration of the optical switch according to the present invention will be described with reference to FIG. FIG. 7 is a perspective view of a state immediately before sealing the package of the optical switch. The figure shows the state in which the cover 706 is removed from the package base 100.

The optical fiber 102 is fixed to the base 104 by the fiber holding block 103. The end of the optical fiber 102 is fixed to a movable fiber holding block 106 made of a soft magnetic ceramic having a movable structure. An end of a guide pin (not shown) is slidably inserted into the groove formed in the movable fiber holding block 106. The other end of the guide pin is fixed to a fiber holding block 107 made of soft magnetic ceramics. The movable fiber holding block 106 is sandwiched between the side yokes 705a and 705b while ensuring a swinging gap. A yoke 109 and a permanent magnet 112 are magnetically connected to the side yokes 705a and 705b, and coils 108a and 108b are connected to the yoke 109.
Is wound. These components are bonded to the base 104, and the base 104 is bonded to the package base 100. The coil electrode 70 is provided on the coils 108a and 108b.
4a, 704b are provided and these are solder 703.
a and 703b, they are electrically connected to the internal electrodes 702a and 702b. The internal electrodes 702a and 702b are electrically connected to the external electrodes 701a and 701b, respectively.

The movable fiber holding block 106 is provided with the permanent magnet 11 via the side yokes 705a and 705b.
2. The magnetic force generated by the coils 108a and 108b causes the optical fiber to oscillate, which causes the optical fiber to move.
2 and the optical fiber 110 can be switched over.

The groove formed in the movable fiber holding block 106 along which the guide pin slides has the structure shown in FIG. 6, and the position of the optical fiber 102 can be switched with high precision.

The cover 706 is bonded to the package base 100 with good airtightness, and a refractive index matching liquid injection hole 707 is used to inject a refractive index matching liquid, and the refractive index matching liquid injection hole cover 708 is airtightly provided. A switch having a coupling loss of light of 1 dB or less can be easily formed by bonding it on the injection hole 707.

[0050]

EFFECTS OF THE INVENTION Even if the machining error of the groove in which the guide pin slides is large, it is possible to construct an optical switch in which the optical coupling loss due to the displacement of the optical fiber in the translation direction is 1 dB or less, and the manufacturing cost of the optical switch is reduced. It can be reduced.

[Brief description of drawings]

FIG. 1 is a top view showing the overall structure of an optical switch.

FIG. 2 is a sectional view showing a sectional structure of an optical switching portion of an optical switch.

FIG. 3 is a cross-sectional view showing a mechanism in which a switching position shift occurs.

FIG. 4 is a sectional view showing a dimensional relationship of a contact portion between a guide pin and a groove.

FIG. 5 is a sectional view of a movable fiber holding block and a guide pin portion.

FIG. 6 is a diagram showing a specific example of dimensions.

FIG. 7 is a perspective view of a state immediately before sealing the package of the optical switch.

[Explanation of symbols]

100 ... Package base, 101 ... Input optical signal, 10
2 ... Optical fiber, 103 ... Optical fiber holding block,
104 ... Base, 105 ... Guide pin, 106 ... Movable optical fiber holding block, 107 ... Fiber holding block, 108a, 108b ... Coil, 109 ... Yoke,
110 ... Optical fiber, 111a, 111b ... Output optical signal, 112 ... Permanent magnet, 201 ... Press plate, 202 ...
Grooves, 701a, 701b ... External electrodes, 702a, 702
b ... internal electrodes, 703a, 703b ... solder, 704
a, 704b ... Coil electrode, 705a, 705b ... Side yoke, 706 ... Cover, 707 ... Refractive index matching liquid injection hole, 708 ... Refractive index matching liquid injection hole cover.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References: Kaihei 4-85412 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02B 26/00-26/08

Claims (5)

(57) [Claims] 1. A first block fixed to an end of a first optical fiber and a second block fixed to an end of a second optical fiber are provided so as to face each other, and the first block is the first block. In a fiber type optical switch that switches the optical path by relatively moving with respect to two blocks, a block moving means for moving the first block by magnetic force, a pair of grooves formed in the first block, A pair of guide pins, one end of which is inserted into the groove and the other end of which is fixed to the second block, and a pressing plate arranged in the first block so as to cover the groove,
The first block is a soft magnetic material, the pair of grooves are formed in a direction along the longitudinal direction of the first optical fiber with the first optical fiber interposed therebetween, the guide pin Has a cross-sectional shape in which the dimension in the depth direction of the groove is smaller than the depth of the groove, and one of the guide pins contacts the side wall of the groove near the first fiber side and the pressing plate, The width of the pair of grooves is configured such that the other of the grooves contacts only the pressing plate. 2. A first block fixed to the end of a first optical fiber and a second block fixed to the end of a second optical fiber are provided facing each other, and the first block is the first block. In a fiber type optical switch that relatively moves with respect to two blocks to switch the optical path, a block moving means for moving the first block by magnetic force, a pair of grooves formed in the first block, A pair of guide pins, one end of which is inserted into the groove and the other end of which is fixed to the second block; and a pressing plate arranged in the first block so as to cover the groove, The pressing plate is a soft magnetic material, the pair of grooves are formed in a direction along the longitudinal direction of the first optical fiber with the first optical fiber interposed therebetween, and the guide pin has a depth of the groove. The dimension in the depth direction is the groove It has a cross-sectional shape smaller than the depth, and one of the guide pins contacts the side wall far from the first fiber side of the groove and the pressing plate, and the other of the guide pins contacts only the pressing plate. A fiber type optical switch having a width of a pair of grooves. 3. The fiber type optical switch according to claim 1, wherein the block moving means is an actuator having a coil and a permanent magnet. 4. The pair of grooves according to claim 1 or 2, wherein the pair of grooves include two side walls, and an angle formed by the side walls and a perpendicular to a surface of the first block on which the pressing plate is disposed is: A fiber type optical switch characterized by being 90 degrees or less. 5. The fiber type optical switch according to claim 1, wherein a cross section perpendicular to the axis of the guide pin is circular.