JPS5831563B2 - light switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical switch that is small and simple in structure.

Conventional mechanical optical switches include those that convert the light emitted from an optical fiber into a parallel beam using an optical lens and switch the optical path using a movable mirror or movable prism installed in the optical path of the parallel beam, and those that mechanically switch the opposing optical fiber. It is broadly divided into things that need to be changed.

FIG. 1 is an example of the former.

In FIG. 1, 1 is an input fiber, 2 and 3 are output fibers, 4°5.6 is an optical lens, and 7 is a movable mirror.

The light emitted from the input fiber 1 is turned into a parallel beam by the optical lens 4, and when the movable mirror 7 is in position A, the parallel beam is reflected at right angles to the direction of incidence, and converged into the output fiber 2 by the optical lens 5.

When the movable mirror 7 is in the position A, the parallel light beam coming out of the optical lens 4 travels straight and is converged on the output fiber 3 by the optical lens 6.

In the optical fiber switch of FIG. 1, optical lenses 4.5.
It is expensive due to the large number of precision optical parts such as the movable mirror 6 and the movable mirror T, and it also has the disadvantage of requiring a high-precision mechanism and assembly process in order to increase the weight of each optical part and the relative positional accuracy of the optical fibers.

FIG. 2 shows an example of an optical switch in which switching is performed by directly moving the fiber end without using an optical lens, a movable mirror, etc., in order to improve the above-mentioned drawbacks.

In FIG. 2, 1 is an input fiber, 2 and 3 are output fibers, 4 is a matching holding iron piece, 5 is a housing, 6 is an input fiber support part, and 7 is a driving magnetic field generator.

As shown in FIG. 2, when the alignment holding iron piece 4 is attracted to the upper corner of the housing 5 by the driving magnetic field, the alignment holding iron piece 4, in which the optical axes of the input fiber 1 and the output fiber 2 coincide, is attached to the housing 5. When it is attracted to the lower angle measuring section, the optical axes of the input fiber 1 and the output fiber 3 coincide, and switching is performed.

In the optical switch shown in FIG. 2, the optical fibers are directly opposed to obtain optical coupling, so the optical axes of the opposing optical fibers must be aligned to 1/10 or less of the core diameter.

When a fiber with a core diameter of 60 .mu..phi. is used, the optical axes of opposing optical fibers must coincide with each other within an error of 6 .mu.m, and strict precision is required for each component.

Therefore, the present invention aims to improve the above-mentioned drawbacks of the prior art, and its objectives are (1) to utilize the magnetic force acting on the ferromagnetic film provided on the movable piece of optical fiber as a driving force during switching; 2) Providing an optical axis alignment function through magnetic attraction between ferromagnetic films around opposing fiber end faces; and (3)
By providing an optical switch that mechanically aligns the optical axes of opposing fibers using the outer peripheral surface of a ferromagnetic film with a uniform thickness as a reference plane, these can be applied alone or in combination. Various optical switches can be formed by this.

The present invention is characterized by having a movable optical fiber piece in which a ferromagnetic film of uniform thickness is provided on the peripheral surface of the optical fiber by electrolytic plating, electroless plating, etc.

Examples will be described below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, in which 1 is an input fiber, 2 and 3 are output fibers, 4 is a ferromagnetic film, 5 is an end face of the input fiber, 6A and 7 is an end face of the output fiber, and 8 is an input fiber. 9 is a fiber holding member, 10 is a drive coil, and 11 is a gap in the holding member 9.

The length between the end face 5 of the input fiber 1 and the fixed end 8 is l (b).
to form a cantilever.

The output fibers 2 and 3 are fixed near the end faces 6 and 7.

In the configuration shown in FIG. 3, a hard magnetic material with a large coercive force is used for the ferromagnetic film, and the periphery of the opposing end faces 5 and the end faces 6 and 7 are
Magnetize so that different magnetic poles are generated around 0.

If a hard magnetic material with a sufficiently large coercive force is magnetized at the saturation point, a uniform magnetization distribution will be obtained, and the component F77L of the magnetic attraction between different magnetic poles perpendicular to the optical axis will be expressed by the first equation.

Here, 6m (wb/m2) is the magnetization strength of the magnetic film, a
(, @ is the outer diameter of the cladding of input fiber 1 and output fiber 2 (the outer diameter of the core if the cladding can be easily removed and a magnetic film is attached to the core), t (m) is the thickness of the magnetic film, g ( 77 +) is the gap between end faces 5 and 6, and d (b) is the axis misalignment between input fiber 1 and output fiber 2. When input fiber 1 receives the attraction force of output fibers 2 and 3 as shown in Figure 3, The origin of the axis deviation amount is selected between output fibers 2 and 3, and Fm is given by equation (4).

Here, p(b) is the distance between the optical axes of the output fibers 2 and 3.

The relationship between and d/a is shown in Fig. 4C.

−The optical axis of input fiber 1 when there is no magnetic attraction force is d
If the fixed end 8 is set so that the =00 point and a force Fe (N) in the direction perpendicular to the optical axis is applied to the vicinity of the end face 5, the relationship between the deflection amount d (b) and Fe (N) is the fifth Formula % Formula % Here, l (@ is the distance between the fixed end 8 and end face 5 of input fiber 1, E (N/rrL2) is the equivalent ratio of 10 input fibers, and ■ (rrL4) is the equivalent ratio of 10 input fibers. It is the second moment of inertia of the target i section, and is −a4 4 for an optical fiber with a circular cross section.

The equilibrium point when considering the magnetic attraction force is given by the following equation assuming that Fm in the fourth equation is equal to Fe in the fifth equation.

The right side of the sixth equation shows a linear change with respect to d/a,
Its slope is the material constant E, the δ771 button and the dimension FLsts
It can be arbitrarily selected by l.

Two typical examples are shown in Figure 4 as a straight line and a straight line.

On the straight line A, stable equilibrium points exist at the points Ha, Y and II, so a self-holding optical switch is constructed.

To switch from the state to the second state, the drive coil 10
A magnetic field perpendicular to the optical axis is applied near the end surface 5,
Equivalently, curve C is moved downward on the vertical axis to become C''.

The stable point moves to E, and if the applied magnetic field is then removed, the stable point moves to C (2), completing the switching.

For reverse switching, the current in the drive coil 10 is reversed, and C is changed to C.
This is possible by moving to ``.

At the straight exit, the initial stable point is at the origin 0 in FIG.

Similar to the above method, if the drive coil 10 moves the curve C to C', the stable point becomes .

If the applied magnetic field is removed, the stable point returns to the origin.

If the current of the drive coil 10 is reversed and C is moved to C'', the stable point becomes G.

In other words, a bipolar optical switch is constructed by reversing the polarity of the drive current.

In this embodiment, as shown in FIG. 5, if the fixed end 8 of the input fiber 1 is set at a position where the end face 5 of the input fiber 1 faces the end face 2 of the output fiber when the first drive coil is not energized, 1. A current holding type optical switch is constructed in which the input fiber 1 and the output fiber 3 are coupled only when the drive coil is energized, and the input fiber 1 and the output fiber 2 are coupled when the drive coil is not energized.

FIG. 6 shows another embodiment of the invention.

In this example, for input fiber 1, output fiber 2:
l=- and six output fibers 3 are provided.

A hard magnetic material is used as the ferromagnetic film 4, and is magnetized so that different magnetic poles are generated around the end face 5 of the input fiber and around the end faces 6, 70 of the other fibers.

The drive coil is 10.1. Two sets are provided: = and 10'.

By selecting the size and polarity of the excitation current of these two sets of drive coils, a magnetic field with a predetermined direction and strength perpendicular to the optical axis is generated near the opposing fiber end faces, and the input fiber 1 is It is possible to couple to the desired output fiber.

FIG. 7 shows another embodiment of the invention.

The input fiber 1 and the output fiber 2 have movable ends 5°6.

The input fiber 2 and the output fiber 2' have ends 5',
It is fixed to the fiber holding member 9 near 6'.

As the ferromagnetic film 4, a hard magnetic material is used.

Magnetization is performed so that magnetic poles of the same polarity are generated around the end faces 5, 5' of the input fiber 1゜1', and magnetic poles of opposite polarity are generated around the end faces 6, 6' of the output fibers 2, 2'. has been done.

Input fiber 1 and output fiber 2 are 1. Drive coil 10
The end faces 5 and 6 are set to face each other when no current is applied.

When the drive coil is energized, end surfaces 5 and 6 receive magnetic forces in mutually opposite directions perpendicular to the optical axis, and end surface 5 is coupled to end surface 6', and end surface 6 is coupled to end surface 5'.

In the embodiment VC of FIG. 7, if the positions of the input fiber 1 and the output fiber 2 are set so as to face the output fiber 2' and the input fiber 1', respectively, when the drive coil 10 is not energized, the The structure is shown in Figure 8.

When the drive coil 100 is energized, the input fiber 1 and the output fiber 2' are coupled.

By using a plurality of the structures described in the above embodiments as basic units, many pairs of optical switches can be easily constructed.

FIG. 9 shows an embodiment of the present invention as a multi-pair optical fiber switch.

This embodiment uses the structure of the embodiment shown in Fig. 3 as a basic unit binding method, 3
The units are arranged in parallel, and the fiber holding member 9 is shared.

Although three sets of drive coils 10 are used in FIG. 10, they can also be shared, and an optical switch that enables simultaneous multi-pair switching can be easily constructed.

In the above embodiments, the drive coil 10 is of the air-core solenoid type and is installed in the gap 11 of the fiber holding member 9, but the present invention is not limited to these embodiments, and as shown in FIG. Various configurations shown in are possible.

10A shows an air-core solenoid coil 10 provided outside the fiber holding member 9. In FIG.

The opening is a fiber holding member installed in the gap of the magnetic core 10-1.

In order to generate a perpendicular magnetic field component near the fiber end faces 5, 6.7, a magnetic circuit is formed in the yoke 10-2 with an air gap, and a winding 10-3 is provided around the fiber holding member. It is something.

As other embodiments of the present invention, there are various structures in which optical axis alignment between fibers is performed using the outer periphery of the magnetic film as a reference.

The optical switch shown in FIG. 11 has the same function as the optical switch shown in FIG. 3, but is characterized in that the fiber holding member 9 has a guide portion 9-1.

The guide part 9-1 is set so that the position where the movable part of the input fiber 1 stops in contact with the guide part 9-1 when moved by the magnetic field of the drive coil 10 is aligned with the optical axis of the output fiber 2 or 3. .

In this example the output fiber 2, ! , - and 3 can be operated without the magnetic films.

However, if a magnetic film is also provided on the output fiber buttons 2 and 3 as shown in Fig. 11, and the buttons are magnetized to create a magnetic attraction force between them and the input fiber 1, magnetic attraction will be applied to the drive and alignment. Power also contributes.

Obtaining optical axis alignment by providing a guide part in this way is the third step.
It is applicable not only to the structures shown in the figure but also to structures such as those shown in FIGS. 5, 6, 7, and 9.

FIG. 12 shows an embodiment in which a mechanical holding mechanism using a guide portion is introduced to the embodiment of FIG. 7.

Another embodiment of the present invention is a structure in which a soft magnetic material is used for the magnetic film.

In all the embodiments shown in 1, if an excitation coil for exciting the magnetic film in the axial direction is provided in addition to the drive coil, and if a soft magnetic material is used as the magnetic film, equal distribution functions can be obtained. That is self-evident.

Here, an embodiment will be described in which excitation and demagnetization of a magnetic film using a soft magnetic material are used for driving.

In Figure 13, button 4 is a magnetic film made of soft magnetic material, 10-2
is a yoke, and 10-3 is a solenoid coil.

When the current of the solenoid coil 10-3 is cut off, the magnetic film 4
Since the residual magnetic flux density is small, it is restored by the elastic force of the optical fiber.

When the solenoid coil 10-3 is energized, an attractive force acts between the end faces 5° and 6, and the input fiber 1 and the output fiber 2 are coupled together.

Although this embodiment is used simply as a switching contact between optical fibers, it is obvious that a configuration having the same function as the embodiment shown in FIG. 8 is possible.

It is also possible to use a combination of soft and hard magnetic materials in other embodiments of the invention.

In the embodiment of FIG. 3, the output fiber 2. ! The ferromagnetic films of the =- and output fibers 3 are made of hard magnetic materials, and are magnetized with opposite polarities.

The ferromagnetic film of the input fiber 10 is made of a soft magnetic material.

If a magnetic field smaller than the coercive force Hch of the hard magnetic material used for the output fibers 2 and 30 and the ferromagnetic film 4 is applied by the excitation coil 11 and a magnetic pole is generated around the end face 5 of the input fiber 1, the polarity can be changed. Input fiber 1 is coupled to output fiber 24 or 3, correspondingly.

If there is air between the end face 5 and the end faces 6 and 70 in FIG. It is effective to attach an antireflection film to 6 and 7.

Furthermore, if the gap in the fiber holding member 9 shown in FIG. 3 is filled with a liquid whose refractive index is close to that of the core of the optical fiber and has a predetermined viscosity, it is possible to not only reduce the loss due to reflection at the interface, but also to Vibration of the movable fiber due to operation can be suppressed.

The ferromagnetic film is formed on the surface of the core residue or cladding by vapor deposition, sputtering, electroless plating, electrolytic plating, etc., or by attaching the residue or cylindrical ferromagnetic material to the optical fiber. It can also be formed.

When a hard magnetic material with a large coercive force He (AT/m) is used as the ferromagnetic film, it is magnetized in the axial direction of the optical fiber, and the magnetization is determined by the demagnetization curve of the magnetic material and the demagnetizing field coefficient of the sample. It utilizes the magnetic poles that occur on the end face depending on the strength of the magnetic field.

In the first equation, considering the case where the magnetization is uniform in the axial direction, the areal density of the magnetic poles generated around the end face is made constant and equal to the magnetization B of the magnetic material, but strictly speaking, the magnetization distribution within the ferromagnetic film is need to be considered.

When a soft magnetic material with a small coercive force He (AT/m) is used as the ferromagnetic film, it is necessary to apply a predetermined magnetic field from the outside in the optical axis direction.

The external magnetic field can be generated by an excitation coil as shown in the embodiments of FIGS. 3 and 5, but is not limited to this, and it is also possible to use a permanent magnet that generates an equivalent magnetic field. .

The effects produced by the configuration of the present invention are as follows.

(1) Since a ferromagnetic film is provided on the circumferential surface of the optical fiber core or cladding, it is easy to obtain a ferromagnetic film that is concentric with the optical axis. The attractive force between the dissimilar magnetic poles acts to align the optical axes of the opposing optical fibers.

This eliminates the need for high-precision components and assembly adjustments required for conventional fiber optic switches.

This makes economicalization easy. (2) Since the basic component is an optical fiber, a compact multi-pair optical switch can be easily obtained by arranging them in parallel by taking advantage of the small cross-sectional area of the optical fibers.

(3) Since optical parts such as lenses are not used, insertion loss due to aberration can be reduced, and low insertion loss can be easily achieved.

(4) Since the optical switch component is an optical fiber, it can also serve as a fiber for external connection.

Loss can be reduced by reducing the number of connection locations.

(5) Since there are no sliding parts, there is no mechanical deterioration due to wear etc.

[Brief explanation of drawings]

Figures 1 and 2 A and B are structural examples of conventional optical switches.
3 is a structural example of an optical switch according to the present invention, FIG. 4 is an explanatory diagram of the operating principle of an optical switch according to the present invention, FIGS. 5, 6, A and B, 7, 8, and 9. Figures A and B, 1st
Figures 0A and 1C, Figures 11A and B, Figures 12A and B, and Figure 13 each show other embodiments of the optical switch according to the present invention. 1.1'...Input fiber, 2,2'...Output fiber 3...Output fiber, 4...Ferromagnetic film, 5,
5'...Input fiber end face, 6, 6'...7...
Output fiber end face, 8..., input fiber fixed end, 9
...Fiber holding member 9-1...Guide portion, 10.
...1 drive coil, 10-1...magnetic core, 10-2...
・Yoke, 10-3...Winding.

Claims (1)

[Claims] 1. At least one first ferromagnetic film having a ferromagnetic film of uniform thickness formed over a predetermined length on the end face or the surface near the end face.
an optical fiber, at least one second optical fiber having a similar configuration and having an end face facing the end face of the first optical fiber with a predetermined distance therebetween, and fixing the end face of the second optical fiber. , a holding member that holds the first optical fiber in a cantilever shape when the end face becomes a movable end; and a holding member that is fixed to the holding member and generates a magnetic field in a direction perpendicular to the optical axis near the end face of the first optical fiber. The first optical fiber and the second optical fiber are each provided with a drive coil, and the first optical fiber and the second optical fiber are magnetized with different types, thereby performing a self-holding optical switching action that is switched by energization of the drive coil. Features a light switch. 2. The optical switch according to claim 1, wherein the holding member has a mechanical guide mechanism at the stop position of the first optical fiber. 3 Fill the gap between the fiber holding members with a liquid whose refractive index is close to the refractive index of the core of the optical fiber and which has a predetermined viscosity to match the refractive index between the opposing optical fiber end surfaces and apply a brake to the movable fiber. Optical switch according to claim 1, characterized in that it provides: