JP2003035875A - Optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switch which does not change its state in spite of the occurrence of a service interruption and curtails electric power consumption during holding of the state. SOLUTION: The position of a reflector plate placed in a movable state in an optical changing over section is set near the reflector plate or on a substrate near the reflector plate and a soft magnetic material is disposed on an opposite substrate or near the reflector plate, by which the optical switch is so constituted as to maintain the changing over position by the timing forces of attraction of a permanent magnet after the movement of the reflector plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix optical switch used for optical communication and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for optical communication capable of transmitting a large amount of information in response to advanced information and multimedia. In this optical communication field, a highly reliable optical switch is required for switching lines between subscribers.

As a conventional optical path switching device having such an optical switch, there is, for example, Japanese Patent Laid-Open No. 2000-98270. This conventional technique uses an electromagnetic force as a driving force of the mirror and has a function of holding the mirror by itself without supplying electric power. Specifically, the semi-cylindrical permanent magnets of the N pole and the S pole are combined into a cylindrical shape, and the N pole and the S pole are combined.
A cylindrical permanent magnet having a mirror attached to the boundary of the poles is prepared, and the cylindrical permanent magnet is housed in a cylindrical support portion. An electromagnet is arranged below the support. Therefore, when a current is applied to the coil of the electromagnet to form a magnetic field having an S pole in the region facing the cylindrical permanent magnet,
The N pole of the permanent magnet is attracted to the S pole of this magnetic field, and the cylindrical permanent magnet rotates to operate the mirror.

[0004]

In the above prior art, as described above, since the cylindrical permanent magnet with the mirror mounted thereon rotates within the cylindrical support member, wear of the cylindrical permanent magnet or the cylindrical housing portion is prevented. However, the reliability as an optical switch was poor.

It is an object of the present invention to provide an optical switch that has no worn parts and has improved reliability.

[0006]

The above object is to provide an optical switch for changing the optical path by inputting input light to a reflector.
A lever having one end supported on the substrate and a reflection plate fixed to the other end surface, a stress applying member superposed on the lever, and a magnet installed on the substrate are provided, and the stress is applied when the optical path is switched. When a member warps the lever and advances the optical path in a straight line, the magnet is used to attract the magnetic portion of the lever.

Further, it is achieved by polymerizing a stress applying portion and a soft magnetic material on the lever.

Further, this can be achieved by installing an adsorption relaxation means on the permanent magnet.

Further, in an optical switch for switching an optical path by inputting input light to a reflecting plate, a lever having one end supported on a substrate and a reflecting plate fixed to the other end surface, and a stress applying member superposed on the lever, Achieved by providing a silicon gel installed on the substrate, the stress applying member warps the lever when switching the optical path, and sucking the lever with the silicon gel when moving straight on the optical path. To be done.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of an optical switch element according to the present invention. In FIG. 1, 110 is a silicon substrate. 109 is a heater formed on the substrate. 10
Reference numeral 8 is a permanent magnet mounted on the heater 109.
107 is an insulating film attached on the silicon substrate 110. Reference numeral 106 is an electrode film attached on the insulating film 107. Reference numeral 105 is an insulating film attached on the electrode film 106. 101 is a mirror. 102 is a stress imparting film. Reference numeral 103 denotes a silicon cantilever for supporting the mirror 101. 104 is an electrode film formed on the cantilever 103.

An electrode film 104 attached to the cantilever 103 and an electrode film 106 attached to the insulating film 107.
Are connected to a power source (not shown), and a voltage is applied in the range of −20V to + 20V, respectively. As a material for the electrode films 104 and 106, gold is generally used, but it is also possible to use any good electric conductor such as copper or aluminum. In addition, FIG.
This shows a state in which no voltage is applied to the electrode films 104 and 106, and the cantilever 103 is held in a state of being warped from the substrate by the action of the stress applying film 102 formed by forming permalloy. . Cantilever 1
As the material of 03, glass, ceramics, or metal can be used in addition to silicon. When a metal is used, the electrode film 104 may be omitted.

The operation of this optical switch will be described with reference to FIG. For example, when a voltage of −20 V is applied to the electrode film 106 and a voltage of +20 V is applied to the electrode film 104, both electrodes 104,
106 attract each other by electrostatic force, and the position of the mirror 101 is switched to the position shown by the dotted line. Both electrodes 104,
When 106 approaches, since the insulating film 105 is formed on the electrode film 106, the electrode film 106 and the electrode film 1
There is no short circuit with 04. As the material of the insulating film 105, silica, silicon nitride, silicon carbide, alumina, glass such as polyimide, ceramics and organic materials can be used.

A permanent magnet 108 is attached to the substrate 110, and the state in which the permanent magnet 108 is attracted to the substrate side can be maintained by the magnetic attraction force with the stress applying film 102. next,
When a voltage of +20 V is applied to both the electrode films 104 and 106, both electrodes 104 and 106 repel each other due to electrostatic force, and the cantilever 103 warps from the substrate 110. When the cantilever 103 does not warp due to only electrostatic force, the heater 109 is energized to raise the temperature of the permanent magnet 108 to the Curie point or higher to reduce the magnetic force.
The cantilever 103 can be warped.

Further, the heater may be replaced with a plane coil. The planar coil is one in which a thin film of a conductor is patterned into a coil shape and an electrode is provided at the end thereof. By energizing the electrodes, a magnetic field in the direction opposite to that of the permanent magnet is applied to the cantilever from the plane coil.
By setting the direction of this magnetic field to be opposite to the direction of the magnetic field of the permanent magnet, the strength of the magnetic field applied to the cantilever can be adjusted.

Since the heater 109 is insulated from the electrode film 106 by the insulating film 107, the action of the electrode films 104 and 106 is not affected even when the heater 109 is energized. As the material of the insulating film 107, glass, ceramics, and organic materials can be used similarly to the insulating film 105. However, when a sufficient force is generated only by the electrostatic force, the heater 109 can be omitted.

Once the cantilever 103 is warped, the magnetic attraction force of the permanent magnet 108 is extremely reduced, so that even if the voltage applied to the electrodes 104 and 106 is removed, it is not attracted to the substrate side. In FIG. 1, if a light beam is applied to the part with a double circle from the front side of the paper surface of the figure, the light beam is applied to switch the reflection and the transmission by changing the state of the mirror. Moreover, each state can be retained without power.

Each of the films formed in this embodiment can be formed by sputtering, vapor deposition or CVD and can be formed by wet or dry etching. The stress applying film 102 made of Permalloy can be formed by plating. By plating, since a thick film can be formed in a short time, the production efficiency can be improved. Further, as the material of the mirror, silicon, glass and organic materials can be used. In the case of silicon and glass, the periphery of the film is removed by dry etching after the film is formed, or a product manufactured by another process is bonded onto the cantilever. A photoresist material used as a photomask can be used as the organic material. After depositing the photoresist, it is exposed to light and developed to dissolve and remove unnecessary peripheral portions to form a mirror. In any case, it is desirable to form a reflective film on the surface to improve the reflectance. The material of the reflective film is aluminum according to the wavelength band of light,
Gold, a dielectric multilayer film, etc. are applied.

In the present embodiment, silicon is used as the substrate 110, but an optical switch element can be similarly constructed by using quartz or ceramics. FIG. 2 is a view corresponding to FIG. 1 with another embodiment of the optical switch element according to the present invention. Note that the same reference numerals as those in FIG. 1 are the same, so the description thereof will be omitted. In FIG. 2, 701 is
It is a soft magnetic film. Soft magnetic film 701 and stress applying film 10
By forming 2 independently, the choice of each material can be expanded. For example, iron having a higher saturation magnetic flux density than permalloy can be used as the soft magnetic film,
A sufficient adsorption force can be obtained even with a thin film.

A material having a higher Young's modulus than a metal such as silicon nitride or silicon carbide can be used as the stress imparting film. In this case, since a sufficient stress can be generated even with a thin film, the mass of the movable part can be reduced and the time required for film formation can be shortened. Further, when a thick metal film is deposited, cracks and the like may occur, but a thin film of ceramics such as silicon nitride or silicon carbide does not easily cause these problems, which is advantageous for production. Furthermore, if silicon is used as the stress-applying film, it can be formed by the same etching process as the silicon cantilever 103, so that the production efficiency can be improved.

FIG. 3 shows another embodiment of the optical switch element according to the present invention. In FIG. 3, 801 is a cantilever. Suitable materials for the cantilever 801 are iron, nickel, cobalt and alloys thereof. With this configuration, the cantilever 801 itself has the functions of an electrode and a stress imparting film, so that the structure of the movable portion is simplified, productivity is improved, and the operating speed can be improved by weight reduction.

FIG. 4 is a structural example of a 4 × 4 matrix optical switch according to the present invention. 201 is a mirror 10 on the top
It is a cantilever equipped with 1. This cantilever 2
Reference numeral 01 is a mirror support member composed of a permalloy stress applying film and an electrode film. Reference numeral 108 is a permanent magnet located below the electrode film 106. Reference numerals 204a to 204d are lines showing the propagation path of the input light. 205a to 205d are lines showing the propagation path of the output light whose direction is changed by being reflected by the mirror 101.

Since each mirror supporting member is formed of the cantilever 210, the stress-imparting film and the electrode film, the member that is warped from the substrate 110 according to the above-mentioned operation principle retains the state as it is. On the other hand, those that are in close contact with the substrate 110 are the permanent magnet 108 on the substrate 110 and the stress imparting film 102 made of permalloy shown in FIG.
By the action of, the state of being in close contact with the substrate 110 is maintained. For example, in the case of the state shown in FIG.
a passes under the first mirror support member on the optical path,
After being reflected by the second mirror and changing its direction, the light further passes under the three mirror support members and is output as output light 205b. Similarly, input light 204b, 204
c and 204d are output lights 205d and 205a, respectively.
And 205c are output. 4 by the above operation
X4 Functions as a light matrix switch.

FIG. 5 shows an embodiment of a structure for holding a cantilever in close contact with a substrate by a permanent magnet. 105
a and 105b are insulating films. 108a, 108b
And 108c are the installation positions of the permanent magnets. When the permanent magnet 108a is installed, a magnetic attraction force acts between the permanent magnet 108a and the permalloy electrode film 104 formed on the cantilever 103. At this time, the electrode film 106 is preferably made of a non-magnetic material. Next, when the permanent magnet 108b is installed, the electrode film 106 formed on the substrate-side insulating film 107 is made of Permalloy, and a magnetic attraction force is applied between the two. At this time, the electrode film 104 is preferably made of a non-magnetic material. Further, instead of the permanent magnet 108b, the permanent magnet 108
You may install c. However, since the distance from the electrode film 106 made of permalloy becomes large, the permanent magnet 108a
In the case of a permanent magnet having the same strength as in the case where or 108b is installed, the magnetic attraction force decreases. Further, when the permanent magnet is installed on the cantilever side (movable side), the mass of the movable portion increases and the operating speed decreases. Therefore, in terms of the operating speed of the movable part, it can be said that it is desirable to install the permanent magnet 108a on the substrate side. Further, as the insulating film, the insulating film 105a and the insulating film 105b can be selected or both can be provided. Even in this case, the insulating film 10 is provided on the cantilever side.
When 5b is installed, the mass of the movable part is increased, but the effect is that the electrode film can be protected from the environment.

By the way, the permanent magnet can be composed of a thin film whose film surface is substantially parallel to the surface of the substrate. A film is formed by sputtering, and a permanent magnet thin film is formed by patterning using a photomask. As a material for the permanent magnet thin film, a cobalt chromium-based permanent magnet, a neodymium iron boron-based permanent magnet, or the like can be used. In order to increase the magnetic field applied from the permanent magnet to the cantilever, it is desirable that the permanent magnet is formed so that the magnetization direction thereof is substantially perpendicular to the film forming surface (the surface of the substrate). That is, it is desirable to impart perpendicular magnetization anisotropy to the permanent magnet thin film.

Cobalt-chromium permanent magnets include cobalt chromium (CoCr) and cobalt chromium platinum (CoCrP).
t) etc. are included. In particular, if a composition containing 10 to 20 wt% of Cr is used, the magnetic field can be strengthened. However, if the thickness of the permanent magnet thin film is too thin, the strength of the magnetic field applied to the cantilever will be weakened. Therefore, it is desirable that the film thickness of the cobalt-chrome-based permanent magnet thin film is 0.1 μm or more. In order to obtain a stronger magnetic field, the film thickness should be 0.5 μm or more. By increasing the magnetic field applied to the soft magnetic film of the cantilever to increase the force with which the permanent magnet thin film attracts the cantilever, in order to increase the magnetizing direction of the permanent magnet thin film, the magnetization direction of the permanent magnet thin film should be more than the direction parallel to the surface of the substrate. It is better to set the direction almost vertical to. The direction of magnetization can be aligned by applying a heat treatment by applying an external magnetic field in the desired magnetization direction after the permanent magnet is formed into a film.

Neodymium iron boron-based permanent magnets include neodymium iron boron (NdFeB) and those to which other additives are added. Since the magnetization of the neodymium iron boron-based permanent magnet thin film is isotropic, a larger attractive force can be obtained by using the CoCr-based permanent magnet thin film. When using a neodymium iron boron-based permanent magnet thin film, in order to obtain a sufficient magnetic field, it is desirable that the thickness of the permanent magnet thin film be 0.5 μm or more to secure a volume.

Further, in order to enhance the force of attracting the soft magnetic material film provided on the cantilever, not only the magnetic field applied to the cantilever by the permanent magnet film is strengthened, but also a soft magnetic material having a high magnetic permeability is provided on the cantilever. Good.

As mentioned above, depending on the structure of the soft magnetic film of the cantilever, when a permanent magnet thin film is used,
The thickness of the permanent magnet thin film may be 0.1 μm or more, more preferably 0.5 μm or more. The thickness of the permanent magnet thin film is preferably smaller than the thickness of the insulating film provided on the substrate.

FIG. 6 shows another embodiment of a suction holding structure for a cantilever according to the present invention. 401a is an adsorption holding material, and 401b is a permanent magnet. Adsorption holding material 401a
By installing the cantilever 103 on the substrate 11
The adsorption holding material 401a adsorbs the electrode film 104 formed on the bottom surface of the cantilever when it is adsorbed to the 0 side by electrostatic force. Even if the electrostatic force is removed, the suction holding force of the suction holding material 401a is maintained, so that the cantilever 103 is held while being held on the substrate side. Silicon gel or the like can be used as the adsorption holding material 401a. Further, a permanent magnet 401b may be used instead of the adsorbent 401a.
However, in this case, the cantilever 103 is replaced by the permanent magnet 40.
The structure is extended to a position facing 1b. Accordingly, the permanent magnet 401b can attract and hold the bottom surface of the cantilever 103.

FIG. 7 is a top view of an embodiment of the wiring of the drive electrodes and heater electrodes of the 4 × 4 optical matrix switch according to the present invention. 501 is a heater electrode, 502
Is a driving electrode.

One set of driving electrodes and one set of heater electrodes are installed for each mirror 101. In this embodiment, all the electrodes are treated independently, but the driving electrodes on the substrate side may be connected to each other to form a common electrode.
Further, the heater electrodes can also be used as a common electrode by connecting one side to each other.

FIG. 8 shows an embodiment according to the present invention in another optical switch. 601 is a mirror, 602 is a mirror supporting substrate, 603 is an elastic supporting beam shown in cross section, 604 is a movable side electrode made of permalloy, 605 is a spacer, 606 is an insulating film, 607 is a substrate side electrode, 608 is a permanent magnet, 609
Is a substrate, 610a is input light, 610b is reflected output light, 6
Reference numeral 10c is a transmitted output light, and 611 is a heater.

When the mirror 601 is separated from the substrate 609, the input light 610a is reflected by the mirror 601 and becomes the reflected output light 610b. When voltages having opposite polarities are applied to the movable electrode 604 and the substrate electrode 607 to attract them, the action of the permanent magnet 608 causes the mirror 60 to move.
1 is adsorbed and held on the substrate 609 side. In this state,
The input light 610a passes through the mirror 601 without being reflected and becomes output light 610c. By the above operation, self-holding optical switching is realized. To separate the mirror 601 from the substrate, voltages of the same polarity are applied to the movable electrode 604 and the substrate electrode 607. When the electrostatic force is insufficient, the heater 611 is energized to turn on the permanent magnet 60.
The mirror 601 can be separated from the substrate by increasing the temperature of 8 above the Curie point and decreasing the magnetic force. The heater 611 can be omitted when sufficient force is generated only by the electrostatic force.

As described above, according to the present invention, since the switching state is maintained even when the power is turned off, the state of the optical switch does not change even if a power failure occurs. In addition, it is possible to provide an optical switch with reduced power consumption when the state is held.

[0035]

According to the present invention, it is possible to provide a highly reliable optical switch having no rotating portion.

[Brief description of drawings]

FIG. 1 is a front view of an optical switch showing the structure of an optical switching element.

FIG. 2 is a front view of an optical switch showing the structure of an optical switching element.

FIG. 3 is a front view of an optical switch showing a structure of an optical switching element.

FIG. 4 is a perspective view of a 4 × 4 optical matrix switch.

FIG. 5 is a partial front view of an optical switch in which a permanent magnet and an insulating film are arranged.

FIG. 6 is a front view of an optical switch capable of self-holding without using a permanent magnet.

FIG. 7 is a top view of a 4 × 4 optical matrix switch.

FIG. 8 is a front view of another optical switch having a self-holding property by a permanent magnet.

[Explanation of symbols]

110 ... Substrate, 109 ... Heater, 108 ... Permanent magnet,
107 ... Insulating film, 106 ... Electrode film, 105 ... Insulating film, 1
01 ... Mirror, 102 ... Stress imparting film, 103 ... Cantilever, 104 ... Electrode film, 106 ... Electrode film, 201 ... Cantilever, 108 ... Permanent magnet, 204a-204d ... Input light propagation path, 205a-205d ... Output light Propagation path, 105a ... Insulating film, 105b ... Insulating film, 108a ...
Permanent magnet, 108b ... Permanent magnet, 108c ... Permanent magnet,
401a ... adsorption holding material, 401b ... adsorption material, 501 ... heater electrode, 502 ... drive electrode, 601 ... mirror,
602 ... Mirror support substrate, 603 ... Elastic support beam, 604
... Movable side electrode, 605 ... Spacer, 606 ... Insulating film, 6
07 ... Substrate side electrode, 608 ... Permanent magnet, 609 ... Substrate,
610a ... Input light, 601b ... Reflected output light, 601c ...
Transmitted output light, 611 ... Heater.

Claims (4)

[Claims] 1. An optical switch for switching an optical path by inputting input light to a reflecting plate, comprising: a lever having one end supported on a substrate and a reflecting plate fixed to the other end surface; and a magnet installed on the substrate. An optical switch characterized in that when the optical path is switched, the lever is warped by the stress applied to the lever, and when the optical path is moved straight, the magnetic portion of the lever is attracted by the magnet. 2. The optical switch according to claim 1, wherein a stress applying member and a soft magnetic material are superposed on the lever. 3. An optical switch according to claim 1, wherein the permanent magnet is provided with an attracting force relaxing means. 4. An optical switch for switching an optical path by inputting input light to a reflecting plate, a lever having one end supported on a substrate and a reflecting plate fixed to the other end surface, and a stress applying member superposed on the lever. A silicon gel disposed on the substrate, wherein the stress applying member warps the lever when switching the optical path, and the silicon gel sucks the lever when the optical path goes straight. And optical switch.