Optical switch

An optical switch comprises a light transmission portion, an optical path-changing portion, an actuator portion and light transmission channels; said light transmission portion having a light reflecting plane provided on one part of a plane facing the changing portion to totally reflect light; said optical path-changing portion being provided in proximity to the light reflecting plane and having an optical path-changing member for reflecting or scattering light; said actuator portion having a mechanism being displaced and transmitting displacement to the optical path changing portion; and said light transmission channels having optical wave guiding bodies and being provided in three directions with the light reflecting plane as a starting point. Switching or dividing of an optical path is conducted by contacting or separating the optical path-changing portion to or from the light reflecting plane by displacement of the actuator portion.

TECHNICAL FIELD

The present invention relates to an optical switch. More specifically, the present invention relates to an optical switch suitable for an optical communication system, an optical storage device, an optical arithmetic unit, an optical recorder, an optical printer and so forth, particularly, for the optical communication system in which a multichannel optical switch is desired to perform switching for each specific beam.

BACKGROUND ART

With recent developments in optical communication technology, optical switches have been sought that allow high-speed response, size reduction, high integration, low power consumption, and reduction of signal attenuation.

Conventionally-known optical switches include the ones in which liquid crystal is used, optical fibers are moved by a mechanical device using an electromagnet, a micromirror is used and so forth.

However, the optical switch using liquid crystal performs switching on the basis of molecular orientation, so that the optical switch has been slow in response and has not been easily adapted to optical communication requiring high-speed communication. There also has been a problem in that utilization efficiency of light is low since a polarizing plate has to be employed.

In the optical switch in which optical fibers are moved by a mechanical device using an electromagnet, the device could not be reduced in size and it has been difficult to meet the demands for a high degree of integration. Additionally, there has been a problem in that power consumption is large as switching is performed by the mechanical operations of an electromagnet.

In the optical switch using a micromirror, the manufacturing process becomes complex and the manufacturing costs are thus high, which is troublesome. There also has been a problem in that attenuation of signals is large since the light is required to propagate through the atmosphere.

In addition to these optical switches, an optical switch is proposed that performs switching by utilizing the change in refractive indexes of optical waveguides due to electro-optic effects during the application of electric fields to the optical waveguides.

However, in this type of optical switch, there is a problem in that the switch is likely to be affected by interference from electric fields applied by other switches by which the other optical waveguides are controlled. Particularly, when an optical switch is reduced in size, electrodes to apply electric fields to each optical waveguide inevitably get close to each other, increasing the interfering effect of electric fields between adjacent optical waveguides and generating errors due to crosstalk and so forth, which has been troublesome.

Additionally, an optical switching element has been proposed that has: a light guide portion for performing light transmission by confining light internally by total reflection; an optical switching portion for extracting the light confined internally to the outside of the light guide portion when the optical switching portion is in contact with the light guide portion, and then reflecting the extracted light into the direction of the desired light guide portion; and a driving portion for driving the optical switching portion (JP-A-11-202222).

However, this optical switching element is configured to let the light guide portion extend light transmission of input light only in one direction. At the same time, the switching element unintentionally outputs the light that is input to the light guide portion, to the outside by contacting the switching portion to an unspecific total reflecting plane of the light guide portion. In other words, the switch only turns light on or off. Accordingly, the following configurations cannot be achieved: a switching element as an optical switch that outputs specific input light after switching or dividing the optical path thereof to a plurality of specific output side ends; an optical switch that outputs a plurality of specific input light to specific output ends by switching each optical path of the input light; and a multichannel optical switch that outputs a plurality of specific input light after switching or dividing the input light to a specific plurality of output ends. Although the switching element may be applicable to objects such as an image display, it has been practically difficult to apply the switching element to an optical communication system.

Moreover, in addition to the configuration whereby the light guide portion extends light transmission only in one direction, the optical switching element is configured to utilize infinitely repeated total reflection of the light guide portion. Thus, an emitting direction at the switching portion, in consideration of refraction at an interface between atmosphere and the light guide portion, is restricted to a deeper angle than the total reflection angle thereof; in other words, an almost vertical direction to the total reflecting plane. Even in this sense, switching to transmit light into different directions for each specific light could not be performed.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the aforementioned problems, and the object of the present invention is to provide an optical switch suitable for an optical communication system, that solves the problems of conventional optical switches, and allows for low power consumption, a high-speed response, size reduction and high integration, significant reduction of signal attenuation and, furthermore, switching per specific input light.

The present inventors, after thorough research to solve the above-noted problems, have discovered that the object mentioned above may be achieved by: providing a light transmission portion having optical transmission channels, consisting of optical wave guiding bodies, in at least three directions with a light reflecting plane at one part on a surface of a light transmission portion, facing an optical path-changing portion, as a starting point. The optical path-changing portion is contacted or separated from the light reflecting plane of the light transmission portion at wavelength levels of input light based on displacement of an actuator portion.

Specifically, according to the present invention, there is provided an optical switch including at least a light transmission portion, an optical path-changing portion and an actuator portion. The light transmission portion has a light reflecting plane provided on at least one part of a plane facing the optical path-changing portion to totally reflect light. Light transmission channels are provided having optical wave guiding bodies in at least three directions with the light reflecting plane functioning as a starting point. The optical path-changing portion is provided in proximity to the light reflecting plane of the light transmission portion in a movable condition and has an optical path-changing member for at least reflecting or scattering light. The actuator portion has a mechanism that is displaced by external signals and transmits the displacement to the optical path-changing portion. The switching or dividing of an optical path is carried out by contacting or separating the optical path-changing portion to or from the light reflecting plane of the light transmission portion by displacement of the actuator portion in response to the external signals. An optical path where the input light from the light transmission channels is totally reflected at the light reflecting plane of the light transmission portion and is transmitted to a specific light transmission channel on an output side when the optical path-changing portion is separated from the light reflecting plane of the light transmission portion. Additionally, an input light from the light transmission channel can be reflected or scattered at the optical path-changing portion, and transmitted to a specific one or more light transmission channels on the output side when the optical path-changing portion is contacted to the light reflecting plane of the light transmission portion.

It is preferable, in the present invention, that the actuator portion has a piezoelectric/electrostrictive element including a piezoelectric/electrostrictive layer and at least one pair of electrodes arranged on one part of the piezoelectric/electrostrictive layer. A vibrating member is provided in contact with at least one part of the piezoelectric/electrostrictive element to support the piezoelectric/electrostrictive element and convert strain of the piezoelectric/electrostrictive layer into bending displacement or vibrations. A fixing member is provided to fix at least one part of the vibrating member so as to vibrate the vibrating member. A displacement transmission member is provided arranged between the optical path-changing portion and the piezoelectric/electrostrictive element and transmits displacement of the piezoelectric/electrostrictive element to the optical path-changing portion.

It is preferable that a ceramic substrate is constituted by unitarily sintering the vibrating member and the fixing member, and that a recessed portion or a hollow portion is formed in the substrate which gives the vibrating member a thin structure. Moreover, the actuator may be a so-called stacked actuator composed of a laminated body in which an anode layer of linking multiple layers as anodes and a cathode layer of linking multiple layers as cathodes are alternately laminated on the piezoelectric/electrostrictive layer composed of ceramics therebetween.

In the present invention, it is more preferable that the light transmission portion includes two or more layers having different light refractive indexes, and that the light transmission channels of the light transmission portion include optical waveguides.

Additionally, the light transmission portion may be configured by joining at least two optical wave guiding bodies to one optical wave guiding body so as to form light transmission channels in at least three directions with the light reflecting plane of the light transmission portion acting as a starting point. Moreover, in the present invention, it is preferable that a condenser lens or a collimator lens is arranged at each of a plurality of light-signal input ends and/or light-signal output ends of the light transmission portion, and that light signals are input and output through the condenser lens or the collimator lens.

In addition, in the present invention, the optical path-changing portion preferably has a light introduction member made of a transparent material. The optical path-changing member may be a light reflector for specularly reflecting or diffusely reflecting light, or a light scattering body for scattering light. In the present invention, the optical path-changing portion may be constituted by a light reflector for diffusely reflecting light or a light scattering body. The light reflector for specularly reflecting or diffusely reflecting light may be a light reflecting film that is integrally formed on a plane of the light introduction member on the side of the displacement transmission member.

Additionally, according to the present invention, a multichannel optical switch having a plurality of the optical switches mentioned above is provided.

As an embodiment in a multichannel optical switch of the present invention, a multichannel optical switch may be included in which each light transmission channel of a plurality of optical switches is formed of a single light transmission portion. The multichannel optical switch is configured to let a part of each light transmission channel share a part of channels by crossing each other.

Other embodiments in multichannel optical switches of the present invention may include the following examples: A switch in which a plurality of optical switches are constituted by linking one input-side channel to one output-side channel between adjacent optical switches, and switching the light input from input ends in an optical switch at each optical path-changing portion of a plurality of optical switches including the optical switch. A switch in which a plurality of optical switches are constituted by at least one optical switch having a plurality of input-side channels and at least one optical switch having a plurality of output-side channels and in which one input-side channel is linked to one output-side channel between adjacent optical switches, and switching the light input from input ends of a plurality of optical switches at the optical path-changing portion of the plurality of optical switches. A switch having a plurality of optical switches in which one input-side channel is linked to one output-side channel between adjacent optical switches by means of optical fiber, and switching at least the light input from input ends in an optical switch at each optical path-changing portion of a plurality of optical switches, or the like.

In the present invention, the multichannel switch, furthermore, may include: The switch in which a plurality of the multichannel switches are arranged in a row; or the switch that has a plurality of the multichannel optical switches, and in which each multichannel optical switch is arranged by locating at least one part of output ends themselves of each light transmission channel in each multichannel optical switch in an arc condition with an input end in an outer light transmission channel, which is disposed separately from each multichannel optical switch, at a center.

Furthermore, the multichannel optical switch may include: The switch in which an optical divider or an optical coupler is joined to a light-signal input end or a light-signal output end of a light signal of each light transmission channel in the multichannel optical switches to branch or collect at least one part of light transmission channels. The switch in which an optical demultiplexer filter or an optical multiplexer is joined to a light-signal input end or a light-signal output end of each light transmission channel in the multichannel optical switches to branch or collect at least one part of light transmission channels. The switch in which each output end or each input end of a plurality of the multichannel optical switches is linked to a plurality of input ends or output ends in at least another similar multichannel optical switch.

Moreover, in the multichannel optical switch of the present invention, it is preferable that each optical path-changing portion has a light reflector and at least two kinds of light reflection angles shared among the optical path-changing portions.

The whole description of the specification of U.S. patent application Ser. No. 09/799,329 filed on Dec. 27, 2000 is incorporated herein by reference.

DETAILED DESCRIPTION THE INVENTION

FIGS.1(a), (b), and (c) are explanatory views schematically showing one embodiment of an optical switch of the present invention: FIG.1(a) shows a state in which an optical path-changing portion is separated from a light transmission portion, FIG.1(b) shows a state in which the optical path-changing portion is in contact with the light transmission portion, and FIG.1(c) shows a plane facing the optical path-changing portion and a plane corresponding to the optical path-changing portion in the light transmission portion. In addition, FIGS.23(a) and23(b) are explanatory views schematically showing a state of operation of another embodiment of an optical switch of the present invention.

As shown in FIG.1(a), under a condition where an actuator portion11is activated by external signals such as voltage in the optical switch of one embodiment of the present invention, an optical path-changing portion8is separated from a light transmission portion1by displacement of the actuator portion11. Light21that is input to light transmission channel2of the light transmission portion1, is totally reflected at a light reflecting plane1aof the light transmission portion1where a refractive index is adjusted to a predetermined value, without transmitting the light. The light is transmitted to one light transmission channel4on an output side.

On the other hand, when the actuator portion11is reversed to a non-activation state from this condition, the displacement of the actuator11is reset as shown in FIG.1(b). A light introduction member9of the optical path-changing portion8contacts the light transmission portion1at a distance less than a wavelength of light. Thus, the light21input to the light transmission channel2is taken to the light introduction member9from the light transmission portion1, and is transmitted through the light introduction member9. The light21transmitted through the light introduction member9reaches an optical path-changing member10. The light is reflected at a reflecting plane10aof the optical path-changing member10constituted with a light reflector which specularly reflects light (hereinbelow sometimes referred to as “a specular reflector”), and is transmitted to another output-side light transmission channel5in a direction different from the direction of the light reflected at the light reflecting plane10aof the optical path-changing member10. On the other hand, as shown in FIGS.23(a) and23(b), the optical path-changing member10includes a light scattering body10fwhich scatters light, or a light reflector which diffusely reflects light (not illustrated, and hereinbelow sometimes referred to as “a diffuse reflector”). The light21which reached the optical path-changing member10changes its optical path in various directions as a result of the light scattering body10for the diffuse reflector and is emitted outside. As a result, the light is transmitted to a plurality of output-side light transmission channels4,5simultaneously.

The optical switch of the present invention shown in FIGS.1(a),1(b), and FIGS.23(a),23(b) performs optical switching. That is, the specific light21introduced into the light transmission channel2of the light transmission portion1may be transmitted to one or more different light transmission channels4,5by optionally switching or dividing an optical path based on external signals such as voltage to the actuator portion11.

Thus, in the optical switch of the present invention, traveling directions of input light or output light may be varied. At the same time, each input light21may be reflected at the light reflecting plane1aof the light transmission portion1or the light reflecting plane10aof the optical path-changing portion8, and may be transmitted to specific output-side transmission channels4,5for each reflected light thereof. Thus, an optical switch may be achieved in which a great number of optical paths may be optionally selected for specific light. In addition, if an optical path-changing portion8provided with a light scattering body10for a diffuse reflector is prepared according to a use, there is realized an optical switch capable of dividing an optical path of the input light21and transmitting the light to a plurality of light transmission channels4,5simultaneously. Additionally, the light transmission channels4,5are switched not by the change in refractive indexes due to physical effects, for instance, electro-optic effects and so forth unique to a material, but by the mechanical operations of contacting or separating the optical path-changing portion8from the light transmission portion1. Thus, not only the size may be reduced but also highly-integrated multichannel switches may be realized without causing problems such as crosstalk. Furthermore, the moving distance of the optical path-changing portion8to perform switching is only in a wavelength order of light, so that high-speed switching may be performed. Moreover, since there is no need for moving the light transmission channels2,4,5themselves, switching can be performed with low power consumption. Also, optical switching may be basically performed in a closed space and there is no need for switching the light that transmits through the atmosphere, so that attenuation of signals relating to switching may be greatly restrained.

Embodiments of the present invention will be explained in detail below for each component based on the drawings.

1. Light Transmission Portion

As shown in FIGS.1(a),1(b),23(a) and23(b), the light transmission portion1in the present invention has the light reflecting plane1athat is provided at least at one part of a surface1dfacing the optical path-changing portion8described below, for reflecting light. The light transmission channels2,4,5, which comprise an optical wave guiding body, transmit light in at least three directions with the light reflecting plane1aoperating as a starting point. Accordingly, as described above, an optical switch is provided in which multiple optical paths may be optionally selected for each specific light or the optical path for the input light21is divided and the light is transmitted to a plurality of light transmission channels simultaneously. Attenuation of signals relating to switching may be restrained to a high degree.

As shown in FIGS.1(a) and1(c), the light reflecting plane1aarranged in the light transmission portion1of the present invention is required to include a part of the portion1bcorresponding to the optical path-changing portion8, in a plane of surface1dfacing the optical path-changing portion8described below. The light reflecting plane1amay also include a plane other than a portion1bcorresponding to the optical path-changing portion8. However, it is preferable that the light reflecting plane1aincludes the portion1bcorresponding to the optical path-changing portion8in order to switch input light effectively.

In addition, the light reflecting plane1aarranged in light transmission portion1to be a starting point of each of the light transmission channels2,4,5, is required to be designed so as to include a plane where the light21input in the light transmission channel2projects into the plane of surface1dof the light transmission portion1which faces the optical path-changing portion8in consideration of disposition of each of the light transmission channels2,4, and5. However, in the present invention, it is not required to make all of the plane1dof the light transmission portion1which faces the optical path-changing portion8, the light reflecting plane1aso long as the light reflecting plane1aincludes a plane where the input light21projects.

The light transmission channels2,4, and5provided in the light transmission portion1of the present invention may include a plurality of light signal input ends and/or light signal output ends, as shown in FIGS.1(a), (b).FIG. 2consists of a single optical wave guiding body and is substantially formed with the light transmission channels2,4,5oriented toward at least three directions, with the light reflecting plane1aof the light transmission portion1being a starting point by providing, at a part of the optical wave guiding body, a plurality of light-signal input ends43and/or light-signal output ends44having a face roughly orthogonal to the input and output direction of light.

However, as shown inFIG. 3, in the light transmission portion1of the present invention, the light transmission channels2,4,5are preferably formed by an optical waveguide1c. If the light transmission channels2,4,5are formed by an optical waveguide1c, light can be transmitted in a narrower space and the attenuation of signals that is troublesome in the case of long-distance communications can be reduced to a high degree.

The optical switch of the present invention may be configured to directly input and output light between optical fibers6or the like and the light transmission portion1by joining the optical fibers6or the like to a plurality of light-signal input ends43and/or light-signal output ends44of the light transmission portion1with an adhesive (not illustrated) or the like. Or, the optical switch may be configured to input and output light between optical fibers6or the like and the light transmission portion1through prisms (not illustrated), by arranging the prisms at a plurality of the light-signal input ends43and/or the light-signal output ends44of the light trans-mission portion1. However, it is preferable to configure the optical switch to input and output light between optical fibers6or the like and the light transmission portion1through lenses7, by arranging the lenses7such as a condenser lens and a collimator lens, at a plurality of the light-signal input ends43and/or the light-signal output ends44of the light transmission portion1as shown in FIGS.1(a), (b), (c) andFIG. 2, thus reducing input and output loss due to light divergence. Particularly, in the optical switch in which the light transmission channels2,4,5(3) composed of an optical wave guiding body are not restricted to a specific direction as shown in FIGS.1(a), (b), (c) andFIG. 2, loss due to light divergence at the light transmission portion1is reduced. Thus, it is preferable to focus light by a condenser lens7and input and output the light between the lens and the light transmission portion1.

Moreover, in the optical switch shown in FIGS.1(a), (b), andFIG. 2, since loss due to light divergence at the light transmission channels2,4,5(3) can be reduced by shortening an optical path length and since loss of light can be reduced by increasing the probability that the scattered light65released in various directions is transmitted to the light transmission channels2,4and5in an optical switch shown inFIG. 23, it is preferable to reduce the thickness indicated as t in the figures. Specifically, the thickness is preferably 1 mm or less, or more preferably 0.5 mm or less.

Furthermore, in an optical switch dealing with specular reflection light as shown in FIGS.1(a),1(b), the directions of the light transmission channels2,4,5are properly determined by relations with refractive indexes between the light wave guiding body, constituting the light transmission channels2,4,5, and the open air (generally air), and by relations with reflection angles at the light reflection member10of the optical path-changing portion8described later.

Similarly, in an optical switch dealing with scattering light65or diffusion light (not illustrated) as shown inFIG. 23, the directions of the light transmission channels2,4,5are properly determined in consideration of a relation of a refractive index between an optical wave guiding body constituting the light transmission channels2,4,5and the open air (generally air).

However, in an optical switch dealing with specular reflection light as shown in FIGS.1(a),1(b), the light transmission channels2,4,5may extend into directions that are appropriate only in these relations. For example, as shown inFIG. 4, in the optical switch having the light transmission channels2a,2b,4a,4b,5a,5bcomposed of an optical waveguide, the light transmission channels can be extended without being paralleled as an input-side light transmission channel2aand another input-side light transmission channel2b. The directions where the transmission channels extend may be changed halfway within a range where light totally reflects in the optical waveguide to form each of the light transmission channels2a,2b,4a,4b,5a,5bby combining straight optical waveguides and non-straight optical waveguides.

In such an optical switch, the degree of freedom in the shapes of the light transmission channels2a,2b,4a,4b,5a,5bis high, and smaller optical switches may be realized.

The optical wave guiding body, constituting the light transmission channels2,4,5, in the present invention has refractive indexes to confine introduced light internally and then transmit the light. The body may be composed of a material having a single refractive index. However, the body is preferably composed of two or more layers having different refractive indexes since light divergence toward laminated layers may be restrained.

Moreover, as shown inFIG. 3, it is particularly preferable that each light transmission channel2,4,5is formed of an optical waveguide. This is because the light transmission channels2,4,5may be easily prepared in complex shapes, and the optical waveguide may be easily joined to each other. In addition to the characteristics of the layered optical wave guiding body, light divergence inside the layers is also restrained, so that light may be transmitted with an extremely small loss.

In the present specification, “optical waveguides” indicate the ones that are composed of a transparent material having a distribution of different refractive indexes and perform light transmission by confining light internally.

The optical wave guiding body is, for instance, one made of: glass, quartz, transparent plastic, transparent ceramics, or the like; a laminated body made of multiple layers having different refractive indexes; and substrates provided with a coating layer of a transparent material on a surface, or the like.

Particularly, as the optical waveguide, there is exemplified the one having a substrate consisting of glass such as quartz glass and alkali borosilicate glass, insulator crystal such as lithium niobate and yttrium iron garnet, compound semiconductor such as gallium arsenide and indium phosphide, plastic (polymer) such as polymethylmethaacrylate (PMMA) and polyimide, or the like. The substrate is formed with a film thereon including a material having a refractive index changed by doping an impurity and so forth to the common system of the material used as the substrate. Also the substrate can include a layer or portion having a different refractive index formed by directly diffusing an impurity and so forth into the aforementioned substrate.

The methods of forming a film on a substrate include, for instance, sputtering method, vacuum deposition methods such as molecular beam epitaxy (MBE), chemical vapor deposition (CVD), liquid phase epitaxy (LPE), vapor phase epitaxy (VPE), thermal polymerization used to form a plastic layer, and so forth. As a method for diffusing impurities or the like, there may be employed impurity ion implantation, impurity ion diffusion, or the like. Moreover, in forming multiple layers, these methods may be repeated. The number of layers may be appropriately selected based on desired objectives. Additionally, in the case of an optical waveguide, the film or layer formed by the above-noted means has to be patterned to provide predetermined light transmission channels2,4,5. The patterning may be performed by, for instance, removing unnecessary portions in photolithography or the like, or by preliminarily setting a masking material on the above-noted substrate and then forming a film or diffusing an impurity to provide predetermined light transmission channels2,4,5.

As shown in FIGS.1(a), (b), and (c), the optical path-changing portion8of the present invention is provided in proximity to the light reflecting plane1aof the light transmission portion1in a movable condition, and it possesses at least a light reflection member10for reflecting or scattering light.

In this way the light21in the light transmission channel2may be optionally reflected (specularly reflected or diffusely reflected) or scattered by the optical path-changing member10to switch the light21to an optical path different from the optical path which the light21is reflected by the light reflecting plane1aof the light transmission portion1or to divide the light21to a plurality of light transmission channels4,5when the optical path-changing portion8is brought into contact with the light transmission portion1.

Moreover, since light may be switched by mechanical operations such as contact or off-contact from the light transmission portion1by displacement of the actuator portion11as mentioned later, a compact and highly-integrated multichannel optical switch may be manufactured without any problems such as crosstalk. In particular, it is very advantageous in an optical switch where an optical path is switched as shown in FIG.1. Furthermore, since the moving distance of the optical path-changing portion8for switching is only in the order of light wavelength, high-speed switching may be performed and an optical path itself does not have to be moved, thus reducing power consumption.

Herein, the meaning of being in “proximity to” the light transmission portion1is defined to mean the optical path-changing portion8is arranged from the light reflecting plane1aof the light transmission portion1at a distance longer than a wavelength of input light21when the actuator portion11is in a non-operable or operable state; and the optical path-changing portion is arranged from the light transmission portion1at a distance shorter than a wavelength of input light21when the actuator portion11is in the reverse condition thereto.

For instance, as shown in FIG.1(a), when the actuator portion11is at an operable state, the optical path-changing portion8may be arranged from the light reflecting plane1aof the light transmission portion1at a distance longer than a wavelength of input light21. As shown in FIG.1(b), when the actuator11is in a non-operable state, the optical path-changing portion8may be arranged from the light reflecting plane1aof the light transmission portion1at a distance same as a wavelength of input light21or shorter. On the contrary, as shown inFIG. 5, the optical path-changing portion8may be arranged from the light transmission portion1at a distance that is the same as a wavelength of input light21or shorter when the actuator portion11is in an operable state. When the actuator portion11is in a non-operable state, the optical path-changing portion8may be arranged from the light transmission portion1at a distance longer than a wavelength of input light21. These differences are based on the structure of a piezoelectric/electrostrictive element, and the driving methods thereof.

An optical path-changing portion8in the present invention may be provided with a specular reflector10dshown in FIGS.1(a),1(b), or a light scattering body10fshown in FIGS.23(a),23(b), or a diffuse reflector (not illustrated). More specifically, the optical switch may include an optical path-changing portion8provided with the specular reflector10das shown in FIGS.1(a),1(b) in the case where the purpose is to switch a specific optical path to another specific optical path. The optical switch may include an optical path-changing portion8provided with the light scattering body10fas shown in FIGS.23(a),23(b) or the diffuse reflector (not illustrated) in the case where the purpose is to divide an optical path to a plurality of other optical paths.

In the present invention, in an optical switch where the optical path-changing portion8is provided with the specular reflector10d, it is preferable that the specular reflector10dexhibits total reflection.

Reflection angles at the specular reflector10dmay be appropriately determined based on the configuration of switches in accordance with the desired application. In addition to the reflection member to reflect light provided having an inclined surface with predetermined angle as shown in FIGS.1(a), (b), and (c), the reflection member may include, for example, a plate optical path-changing member10arranged in a flat condition at an angle of 0° as shown in FIG.9. The optical path shown by a broken line inFIG. 9shows an optical path when the optical path-changing portion8is brought into contact with the light transmission portion1.

Also, reflection angles of the specular reflector10dmay be the angles, as shown in FIGS.1(a), (b), and (c), to switch an optical path of light21that is input to one light transmission channel2and is transmitted to the light transmission channel4on an output side, to an optical path of light that is reflected at the specular reflector10dof the optical path-changing portion8and is transmitted to the light transmission channel5on another output side. The reflection angles of the light reflection member10may be the reflection angles, as shown inFIG. 2, to switch an optical path of light (not illustrated) that is input to the light transmission channel2on an input side and is transmitted to the light transmission channel4on an output side, to an optical path of light21that is input to the light transmission channel3on another input side and is transmitted to the light transmission channel4on the same output side. In the case that the specular reflection is total reflection, this reflection angle satisfies conditions of total reflection.

The specular reflector10din the present invention includes, for instance, a plate specular reflector made of a light reflecting material that is arranged with a predetermined inclination, or a specular reflector such as a trigonal prism and a rectangular parallelepiped made of a light reflecting material that is arranged with a predetermined inclination, and so forth.

The specular reflector may also include an electrode16having a light reflecting surface as described later and having functions as the specular reflector10das shown in FIG.7. Furthermore, as shown inFIG. 5, the specular reflector10dmay have a substrate10cof a trigonal prism, rectangular parallelepiped and so forth formed with a light reflecting film10b. The specular reflector10das shown inFIG. 6may be the one having the light reflecting film10bitself that is formed integrally on the light introduction member9of a trigonal prism, a rectangular parallelepiped or the like at the side of a displacement transmission member12, and so forth.

Among them, since reflection angles of a light reflection member may be accurately set, the light reflection member10having the substrate10cof a, trigonal prism, rectangular parallelepiped or the like formed with the light reflecting film10b, as shown inFIG. 5, or a reflector such as a trigonal prism and a rectangular parallelepiped made of a light reflecting material that is arranged with a predetermined inclination is preferable.

Also, it is preferable that the light reflecting film10bis formed integrally on the light introduction member9of a trigonal prism, a rectangular parallelepiped or the like at the side of the displacement transmission member12as shown in FIG.6and the displacement transmission member12may be made of an elastic material in the point that the number of components can be reduced, manufacturing costs may be low, and contact precision between the optical path-changing portion8and the light transmission portion1may improve.

The light reflecting film10bis formed on the light introduction member9on the side of the displacement transmission member12in the optical switch shown in FIG.6. This is because precision of reflection angles could not be maintained due to the characteristics of the displacement transmission member12if the film is formed on the displacement transmission member12. Accordingly, it is preferable that the light introduction member9has a hardness so as not to change the angle of a light reflection member by the operation of the actuator portion11in such an optical switch.

Materials having high reflective efficiency of light are preferable for the specular reflector in the present invention. The materials include, for instance, single metal, alloy, glass, ceramics, rubber, organic resin and so forth by itself or the combination of two or more kinds thereof. The single metal and the components of the alloy include aluminum, titanium, chromium, iron, cobalt, nickel, silver, copper, tin, tantalum, tungsten, iridium, platinum, lead, and so forth.

When two or more kinds of these materials are used in combination, the light reflection member10may contain two or more kinds of the materials uniformly, but may also be a layered member, each of the layers consisting of a material different from the others. Additionally, the optical path-changing member10, as a whole, may consist of the materials. As shown inFIG. 6, the member may be one formed with the light reflecting film10bon the surface.

As method of forming the light reflecting film10b, there may be employed, for instance, thin film forming methods such as a vacuum deposition method, a sputtering method, a plating method, an ion plating method, an ion beam method, or a CVD method.

On the other hand, in an optical switch where an optical path-changing portion8as shown inFIG. 23is provided with a light scattering body10for a diffuse reflector (not illustrated), an angle of the surface is not preferred, and the light scattering body10for a diffuse reflector may be disposed in a position where a loss of scattering light65or diffuse reflection light is small from a positional relation with each of the light transmission channels2,3and4.

In addition, a diffuse reflector in the present invention may have the same structure basically as the aforementioned specular reflector and have a roughened reflecting surface. The roughening may be within a suitable range in consideration of a wavelength of light to be transmitted, and a general method of roughening may be employed.

A light scattering body10din the present invention may be prepared by dispersing, for example, a ceramic powder of zirconia, titania or the like, a metal oxide powder of lead oxide or the like, a mixture powder thereof, or the like, in, for example, an epoxy, acrylic, or silicone transparent resin in view of emission efficiency and maintaining flatness.

At this time, the light scattering body10dpreferably includes 10-100 mass parts of a ceramic powder, a metal oxide powder, or a mixture thereof relative to 100 mass parts of the transparent resin.

In addition, in the case that the whole optical path-changing portion is constituted with the light scattering body10f, it is preferable that 10-100 mass parts of a glass powder having an average particle size of 0.5-10 μm is further mixed with the composition relative to 100 mass parts of a ceramic powder. In a light scattering body10dhaving such a composition, contact ability and separating ability with a light transmission portion are improved.

In the present invention, a light introduction member9is not always necessary, and in, for example, an optical switch where an optical path-changing portion8as shown in FIGS.23(a) and23(b) is provided with a light scattering body10for a diffuse reflector (not illustrated), the optical path-changing portion8may be constituted only by the light scattering body10for the diffuse reflector and have a structure whereby the light scattering body10for the diffuse reflector is brought into direct contact with the light transmission portion.

However, in an optical switch where the optical path-changing portion8as shown in FIGS.1(a) and1(b) is provided with a specular reflector10d, it is preferable that a light introduction member9of a transparent material is disposed on the specular reflector10din the point that a contact ability between the optical path-changing portion8and the light transmission portion1can be optimized by specializing a light introduction function and an optical path-changing function.

In addition, even in an optical switch where an optical path-changing portion8is provided with a light scattering body10for a diffuse reflector (not illustrated), it is preferable to have a light introduction member9of a transparent material on the light scattering body10for the diffuse reflector as shown inFIG. 24in the similar point as in the optical switch provided with a specular reflector.

As shown inFIG. 24, in an optical switch where an optical path-changing portion8is provided with a light scattering body10for a diffuse reflector (not illustrated), in the case where light is input almost perpendicularly to a reflecting plane1aof the light transmission portion1from the light transmission channel3, the input light21is divided to be transmitted to the light transmission path29and4which are divided right and left with the light transmission channel3being located therebetween.

A material of the light introduction member9is preferably a transparent material which has a smaller difference in refractive indexes with the light transmission portion1than the difference in refractive indexes between the light transmission portion1and the open air (generally air). This makes it possible to take out the light from the light transmission portion1and return the light to the light transmission channels4,5of the light transmission portion1when the optical path-changing portion8is in contact with the light transmission portion1. A transparent material having roughly the same light refractive index as the light transmission portion1is more preferable. A material to give such quality may include, for instance, glass, quartz, transparent plastic, transparent resin, transparent ceramics, and so forth.

However, in the present invention, the light introduction member9may also be entirely or partially composed of transparent liquid by providing the transparent liquid between the optical path-changing member10or the light introduction member9and the light transmission portion1. In this case, the transparent liquid effectively fills up a gap between the optical path-changing member10or the light introduction member9and the light transmission portion1, so that optical paths may be easily altered.

As a transparent liquid, there may be employed, for instance, organic solvents of low vapor pressure, oil, and so forth. A transparent liquid may be selected in consideration of a difference in refractive index between the liquid and the light transmission portion1and between the liquid and the light introduction member9.

As a method of holding fluid transparent liquid on the optical path-changing portion, for example, a conventional art in which a wall in an appropriate height is provided at an upper outer periphery of the optical path-changing portion8, and so forth may be adapted. However, a method is preferable in which the light introduction member9is formed with recessed and protruded parts or porous parts, and transparent solution is held in a capillary phenomenon by impregnating transparent solution thereto. In addition, when volatile transparent liquid is used, it is preferable to adapt a configuration in which the optical path-changing portion8is sealed airtight with the light transmission portion1to avoid vaporization.

On the other hand, in the light introduction member9of the present invention, the area where the light introduction member9is in contact with the light reflecting plane1aof the light transmission portion1determines the amount of light taken out to the optical path-changing member10. Thus, a surface9aof the light introduction member facing the light transmission portion1is preferably made wider so as to include a whole plane where the light21input in the light transmission channel2projects.

It is preferable that the surface9afacing the light reflecting plane1aof the light transmission portion1is flat so as to secure the surface for a contact area with the light transmission portion1. Specifically, the flatness is preferably 1 μm or less, more preferably 0.5 μm or less, and further preferably 0.1 μm or less. The flatness of the surface9afacing the light reflecting plane1aof the light transmission portion1is important in order to reduce a gap under the condition where the light introduction member9is in contact with the light reflecting plane1aof the light transmission portion1. The flatness is not necessarily limited to the one mentioned above as long as the contact part deforms in the contacting state. However, it is preferable that the flatness is small enough in comparison with a displacement of the actuator portion11.

On the other hand, the flatness of the surface9aof the light introduction member9is preferably 0.005 μm or more, and more preferably 0.015 μm or more so that separation may be securely performed when the light introduction member9in contact with the light reflecting plane1aof the light transmission portion1is separated.

“Flatness” described here includes both surface roughness and undulation.

Moreover, the thickness of the light introduction member9is preferably less than 50 μm, more preferably less than 20 μm, so as to reduce the loss of light.

The actuator portion11in the present invention has functions of displacing with external signals and of transmitting the displacement to the above-noted optical path-changing portion8, thus allowing the switching by mechanical operations, such as contacting or separating (off-contacting) the optical path changing portion from the light transmission portion.

The actuator portion11may be, for instance, one that generates displacement by an elastic body such as a plate spring. However, in view of excellent controllability and high-speed responsiveness, the actuator portion is preferably one that has a displacement transmission portion12, a piezoelectric/electrostrictive element14, a vibrating member18and a fixing member19. This type of the actuator portion11will be explained in detail below for each component.

(1) Displacement Transmission Member

The displacement transmission member12in the present invention is arranged between the optical path-changing portion8and the piezoelectric/electrostrictive element14. The member is arranged in order to transmit displacement of the piezoelectric/electrostrictive element14to the optical path-changing portion8and to set a contact area between the optical path-changing portion8and the light transmission portion1at a predetermined size. In particular, a type of piezoelectric/electrostrictive element14generating bending displacement shown inFIGS. 1,FIG. 5, or the like, is extremely effective in averaging the amount of displacement distributed within the piezoelectric/electrostrictive element14and contacting or separating a whole surface of the optical path-changing portion8evenly from the light transmission portion1.

The displacement transmission member12preferably has a configuration where the member may be in contact with both optical path-changing portion8and the piezoelectric/electrostrictive element14in a large area to allow effective transmission of displacement of the piezoelectric/electrostrictive element14to the optical path-changing portion8.

A material of the displacement transmission member12preferably has a hardness to allow direct transmission of displacement of the piezoelectric/electrostrictive element14to the optical path-changing portion8. As materials having such quality, there may be employed, for instance, rubber, organic resin, organic adhesive film, glass, and so forth. Among these, organic resin made of an epoxy-based, acrylic-based, silicone-based, polyolefine-based or the like organic material, or organic adhesive films are preferable. Organic resin or organic adhesive films in which curing and shrinkage are restrained by mixing a filler into these organic materials, are more preferable.

The displacement transmission member12is arranged by laminating the displacement transmission member12onto the piezoelectric/electrostrictive element14. The method for lamination may be, for instance, a method of lamination with an adhesive, a method of coating the above-noted material of the displacement transmission member as solution, paste or slurry onto the piezoelectric/electrostrictive element14, a method of bonding an organic adhesive film by heating, and so forth. Since an adhesive is unnecessary, the method of bonding an organic adhesive film by heating is preferable. In addition, in order to effectively utilize displacement of the piezoelectric/electrostrictive element14, it is preferable to cut the layer of the displacement transmission member12into about the same shape as the piezoelectric/electrostrictive element14or to provide a notch.

In an optical switch where a light transmission channel is switched with an optical path-changing portion being provided with a specular reflector, it is preferable that a plate member13is further disposed on the displacement transmission member12as shown inFIG. 8in consideration of maintaining the reflection angle of the optical path-changing member10at a predetermined angle.

As a material of the plate member13, in order to maintain flatness of the plate member13, a material in which ceramic powder such as alumina, zirconia, titania, glass or the mixture thereof is dispersed in epoxy-based, acrylic-based, silicone-based or the like organic resin, is preferable. In this case, it is preferable to have ceramic powder dispersed therein at 10 to 100 mass parts relative to 100 mass parts of organic resin.

On the other hand, the displacement transmission member12is not necessarily required. As shown inFIG. 7, displacement of the piezoelectric/electrostrictive element14may be directly transmitted to the light introduction member9without providing the displacement transmission member between the piezoelectric/electrostrictive element14and the optical path-changing portion8.

The piezoelectric/electrostrictive element14in the present invention has a piezoelectric/electrostrictive layer15, and at least one pair of electrodes16,17arranged on at least one part of the piezoelectric/electrostrictive layer15. Here, “piezoelectric/electrostrictive” means piezoelectric and/or electrostrictive.

The piezoelectric/electrostrictive element14generates displacement by the application of voltage to the electrodes16,17. An element that achieves displacement in the thickness direction of the piezoelectric/electrostrictive layer15, is preferable in the point that displacement of the piezoelectric/electrostrictive element14may be transmitted as is, as displacement or vibrations in the direction of the light transmission portion1, to an optical path-changing portion8.

The piezoelectric/electrostrictive element14may have a structure of having one piezoelectric/electrostrictive layer15, or a structure of having multi-layered piezoelectric/electrostrictive layers15of two, three or more layers. When the structure has a multi-layered piezoelectric/electrostrictive layers15, it is generally enough to dispose a pair of electrodes16,17in every piezoelectric/electrostrictive layer15. Alternatively, the piezoelectric/electrostrictive element14may have a so-called laminated (stacked) piezoelectric/electrostrictive element, where each piezoelectric/electrostrictive layer15and each electrode16,17are laminated alternately.

As a material of the piezoelectric/electrostrictive layer15, piezoelectric ceramics are preferable. However, the material may be electrostrictive ceramics, ferroelectric ceramics or antiferroelectric ceramics, and so forth. The material may either require polarization or not. Also, the material is not limited to ceramics, and may be a piezoelectric material consisting of polymer such as PVDF (polyvinylidene fluoride) and so forth, or a complex of the polymer and ceramics.

Specifically, piezoelectric ceramics or electrostrictive ceramics may include one of lead zirconate, lead titanate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead antimony stannate, lead manganese tungstate, lead cobalt niobate, barium titanate, sodium bismuth titanate, bismuth neodymiumtitanate (BNT system), potassium sodium niobate, strontium bismuth tantalate, and so forth singly, as a mixture, or as a solid solution thereof.

These ceramics are preferably a main component at 50 wt. % or more in the ceramic components constituting a piezoelectric/electrostrictive body. Particularly preferable materials are materials containing lead zirconate titanate (PZT system) as the main component, material containing lead magnesium niobate (PMN system) as the main component, material containing lead nickel niobate (PNN system) as the main component, materials containing a mixture or a solid solution of lead zirconate, lead titanate, and lead magnesium niobate as the main component, materials containing a mixture or a solid solution of lead zirconate, lead titanate, and lead nickel niobate as the main component, and materials containing sodium bismuth titanate as the main component in view of having high electromechanical coupling factor and piezoelectric/electrostrictive constant number and being easily capable of obtaining one having a stable material composition.

In the present invention, there may be employed ceramics further containing one or more oxides of lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium, bismuth, tin, and so forth. For example, to a mixture of lead zirconate, lead titanate and lead magnesium niobate as the main component, is added lanthanum and/or strontium, which sometimes enables adjustment of coercive electric field or piezoelectric properties.

As antiferroelectric ceramics, preferable ceramics are: ceramics that have lead zirconate as a main component; ceramics that have a component consisting of a mixture or a solid solution of lead zirconate and lead stannate as a main component; ceramics that have lead zirconate as a main component with lanthanum oxide added thereto; and ceramics that have a mixture or a solid solution of lead zirconate and lead stannate as a main component with lead niobate added thereto.

The thickness of the piezoelectric/electrostrictive layer15is preferably 5 to 100 μm, more preferably 5 to 50 μm, and further preferably 5 to 30 μm. Moreover, the piezoelectric/electrostrictive layer15may be either dense or porous. When the layer is porous, the porosity is preferably less than 40%.

The electrodes16,17may include, as shown inFIG. 1, FIG.8and so forth, the first electrode16formed on at least one part of a surface of the piezoelectric/electrostrictive layer15on the side of the optical path-changing portion8, and the second electrode17formed at least one part of a surface of the piezoelectric/electrostrictive layer15on the side of the substrate20as mentioned above. The first and second electrodes16,17can be formed in a comb shape on either or both surfaces of the piezoelectric/electrostrictive layer15on the side of the optical path-changing portion8or the substrate20as shown inFIG. 9(FIG. 9showing an optical switch formed on a surface on the side of the optical path-changing portion8), and so forth.

As a material for the electrodes16,17, a conductive metal that is generally solid at room temperature is employed. It is preferable to employ, for example, a single metal or alloy of two or more kinds selected from aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, rhodium, silver, tin, tantalum, tungsten, iridium, platinum, gold, lead and so forth, or a combination of two or more systems thereof.

Also, the material may be a mixture of these materials and aluminum oxide, zirconium oxide, silicon oxide, glass, a piezoelectric/electrostrictive material or the like, or a cermet thereof.

Upon selection of these materials, it is preferable to select a material for the first electrode16and the second electrode17, depending on a method of manufacturing the piezoelectric/electrostrictive element14, described later.

For example, for an electrode formed before heat treatment of the piezoelectric/electrostrictive layer15, a material containing a platinum group metal such as platinum, rhodium and palladium is preferable among the materials since the metal has resistance under a high-temperature oxide atmosphere during the heat treatment of the piezoelectric/electrostrictive layer15. An electrode material is more preferable that has a platinum group metal such as platinum, rhodium and palladium, or an alloy containing the platinum group metal such as silver-platinum, platinum-palladium and platinum-silver-palladium as a main component. On the other hand, for an electrode after heat treatment of the piezoelectric/electrostrictive layer15, there may be used a metal having low melting point, such as aluminum, gold, or silver.

In case of the piezoelectric/electrostrictive element14in which the first electrode16and the second electrode17are formed on a surface of the piezoelectric/electrostrictive layer15on the side of the optical path-changing portion8or the substrate20as shown inFIG. 9, it is preferable to form both the first electrode16and the second electrode17from the same material.

Also, the electrodes16,17may have an appropriate thickness, depending on the purposes, but preferably 0.1 to 50 μm in thickness.

A method of forming the piezoelectric/electrostrictive element14on the vibrating member18may include: (1) a method of forming a precursor of the piezoelectric/electrostrictive layer15by a press molding method with a mold or a tape forming method with slurry materials and so forth, preliminarily forming the electrodes16,17on the precursor of the piezoelectric/electrostrictive layer15by a film forming method, thermo-compression bonding the precursor of the piezoelectric/electrostrictive layer15and the electrodes16,17to the vibrating member18, and co-firing the precursor of the piezoelectric/electrostrictive layer15, the electrodes16,17and the unfired vibrating member18. (2) a method of forming a precursor of the piezoelectric/electrostrictive layer15by a press molding method with a mold or a tape forming method with slurry materials and so forth, preliminarily forming the electrodes16,17on the precursor of the piezoelectric/electrostrictive layer15by a film forming method, firing the precursor of the piezoelectric/electrostrictive layer15and the electrodes16,17to prepare a sintered piezoelectric/electrostrictive element14, and bonding the sintered piezoelectric/electrostrictive element14to the substrate20that has the vibrating member18and the fixing member19integrally by firing. (3) a method of forming the second electrode17, the piezoelectric/electrostrictive layer15and the first electrode16sequentially on the sintered vibrating member18by a film forming method, and then firing all the layers17,15, and16simultaneously or firing each of the layers17,15, and16each time, and so forth. Among these methods, the method (3) is preferable.

The word “precursor” here means a thing which has a material constituting a piezoelectric/electrostrictive layer15as the main component and which becomes a piezoelectric/electrostrictive body by a thermal treatment or being fired. In addition, the word “precursor” for an electrode or the like, which is described later, likewise means a thing which becomes an electrode or the like by a thermal treatment or the like.

As a film forming method, there may be employed, for example, thick film methods such as screen printing, dipping, electrophoresis, spraying or coating; or thin film methods such as ion beam, sputtering, vacuum deposition, ion plating, chemical vapor deposition (CVD) and plating; and so forth. Among them, thick film methods such as screen printing are preferable.

The thick film methods such as screen printing have advantages which include being able to simultaneously form leads to electrodes and terminal pads and the piezoelectric/electrostrictive layer15may be formed by using paste or slurry having ceramic particles as a main component, so that preferable piezoelectric characteristics may be obtained. Also, the piezoelectric electrostrictive element14and the vibrating member18may be joined integrally without using an adhesive, so that the methods are highly reliable and reproducible and, furthermore, they may be easily integrated.

Moreover, in case of forming patterns in a desirable shape by a film forming method, predetermined patterns may be formed by screen printing, photolithography, and so forth. Patterns may be formed by removing unnecessary parts by machining such as laser beam machining, slicing and ultrasonic machining. However, in accordance with industrial viewpoints, screen printing is preferable. Additionally, the electrodes16,17may be formed by a method of forming electrodes through a through-hole46as shown in FIG.8.

Firing temperature of the films may be properly determined, depending on the materials thereof, but the temperature is generally 500 to 1400° C. Particularly, for the piezoelectric/electrostrictive layer15, 1000 to 1400° C. is preferable. Additionally, it is preferable to fire the piezoelectric/electrostrictive layer15in the presence of a source of vaporization which controls vapor pressure of components constituting the piezoelectric/electrostrictive layer.

Moreover, any shape may be adapted for the piezoelectric/electrostrictive layer15, the first electrode16and the second electrode17, depending on the purposes. The shapes may include, for instance, polygons such as a triangle and square, curves such as a circle, ellipse and ring, comb shapes, lattice shapes, or the combination thereof.

The piezoelectric/electrostrictive layer15, the first electrode16, and the second electrode17formed on the substrate20may be formed integrally with the substrate20treating each of the layers17,15, and16with heat every time after formation of each of the layers17,15, and16as described above. Alternatively, after forming all the layers17,15, and16, these layers17,15, and16may be simultaneously treated with heat to integrate them with the substrate20. Additionally, in case of forming the first electrode16and the second electrode17by a thin film method, heat treatment is not always necessary to integrate these electrodes.

Subsequently, as a modification of the piezoelectric/electrostrictive element14of the present invention, a so-called laminated (stacked) piezoelectric/electrostrictive element will be explained.

As shown inFIG. 10, this piezoelectric/electrostrictive element34is a laminate which includes an anode layer22in which a plurality of layers functioning as anodes are linked, and a cathode layer23in which a plurality of layers functioning as cathodes are linked, and both are alternately laminated with the piezoelectric/electrostrictive layer24therebetween.

The piezoelectric/electrostrictive element34can utilize displacement in the Y direction, which is a direction of lamination, and in the X direction, which is a direction perpendicular to the direction of lamination. However, as shown in FIG.10(a), in the case of utilizing displacement in the Y direction of a laminate direction, it is preferable to make the piezoelectric/electrostrictive element34longer in the Y direction, direction of lamination, than in the X direction, direction perpendicular to the direction of lamination. This is because, when direction Z of displacement is Y direction, the amount of displacement is a total of displacements in a thickness direction of each piezoelectric/electrostrictive layer.

On the other hand, in utilizing displacement in the X direction, which is a direction perpendicular to the direction of lamination, as shown in FIG.10(b); the piezoelectric/electrostrictive element34is preferably longer in the X direction, than in the Y direction, which is a direction of lamination. The amount of displacement becomes a displacement in proportion with the length of each piezoelectric layer21in the X direction.

In addition, if a size in a direction different from the direction Z of displacement, i.e., X direction in a piezoelectric/electrostrictive element34shown in FIG.10(a) or Y direction in a piezoelectric/electrostrictive element34shown in FIG.10(b) is large, stress of a distortion in the direction becomes large, which influences occurrence of the main displacement (displacement in Z direction).

As a method for producing such a laminated piezoelectric/electrostrictive element34, there may be employed the following method.

As shown inFIG. 11, a precursor25of a piezoelectric/electrostrictive layer is formed by the press molding method or tape forming method with slurry materials and so forth mentioned above. On the obtained precursor25, precursors27and28of electrode layers each having predetermined pattern are formed by a film-forming method such as screen printing to obtain complex precursors255and256.

Next, these complex precursors255and256are subjected to alternate lamination and compression bonding to obtain a laminated body26having a predetermined number of each of the layers. Then, the laminated body26is fired.

Then, the fired laminated body26is cut to expose each of the electrode layers22and23to one of the two surfaces in parallel with the direction of lamination and facing each other.

Then, each of joint layers22aand23ais formed on each of the surfaces where each of the electrode layers22and23are exposed by the aforementioned film-forming method such as screen printing. The joint layers22aand23aare fired and each of the electrode layers22, which functions as an anode, are joined with other electrode layers22, and each of the electrode layers23, which functions as a cathode, are joined with other electrode layers23to obtain a laminated piezoelectric/electrostrictive element34.

The thus obtained laminated piezoelectric/electrostrictive element34is preferably cut in a direction of lamination so that portions to serve as a common fixing member19are left at constant intervals. By this method a plurality of laminated piezoelectric/electrostrictive elements34can easily be produced on the same fixing member19. In such a laminated piezoelectric/electrostrictive element34, the fixing member19can be commonly used, and the vibrating member18is not always necessary. Therefore, reducing the number of switch parts can be accomplished in some applications.

In the case of forming a plurality of laminated piezoelectric/electrostrictive element34by such a method, it is preferable that at least one of the joint layers22aand23ais preferably formed with being separated in each element.

In such a laminated piezoelectric/electrostrictive element34, the laminated body26may be formed by screen printing in addition to press molding methods, tape forming methods, or the like.

It is preferable that the electrode layers22and23constituting a part of the piezoelectric/electrostrictive element34are formed of metal having, in particular, resistance in an oxidizing atmosphere at high temperature in the case when the electrode layers are subjected to a heat treatment simultaneously with or at about the same temperature as that for firing of the piezoelectric/electrostrictive layer24. The cutting process where these electrode layers22and23are exposed may performed to the laminated body26before being fired.

Further, the joint layers22aand23aformed after firing the laminated body26may be formed with a material different from that of the electrode layers22and23. The method for producing the laminated piezoelectric/electrostrictive element34is similar to that of a general piezoelectric/electrostrictive element except for the aforementioned matters, and description for such matters is omitted here.

The vibrating member18in the present invention is in contact with at least one part of the piezoelectric/electrostrictive element14to support piezoelectric/electrostrictive element14, and converts strain of a piezoelectric/electrostrictive layer into bending displacement or vibrations.

The vibrating member18is preferably in a plate shape since this is a shape that is likely to vibrate into the direction of the light transmission portion1. In this case, the thickness of the vibrating member18is preferably the same dimension as the thickness of the piezoelectric/electrostrictive layer15described above. Thus, the vibrating member18is likely to follow sintering shrinkage of the piezoelectric/electrostrictive layer15, so that stress at an interface between the piezoelectric/electrostrictive layer15or the electrode layers16,17and the vibrating member18decreases and the layer and the member may be easily integrated.

Specifically, the member is preferably in the thickness of 1 to 100 μm, more preferably in the thickness of 3 to 50 μm, and further preferably in the thickness of 5 to 20 μm. Also, a ratio of thickness in comparison with the piezoelectric/electrostrictive layer15(vibrating member: piezoelectric/electrostrictive layer) is preferably 1:0.5 to 1:10, and more preferably 1:1 to 1:5.

It is preferable that the vibrating member18directly supports the piezoelectric/electrostrictive element14without a material such as an inorganic or organic adhesive in consideration of degeneration with the passage of time, heat resistance and weather resistance.

Also, it is preferable that a material of the vibrating member18is highly heat resistant in order to prevent the vibrating member18from degenerating during forming the piezoelectric/electrostrictive layer15or the like. Moreover, the vibrating member18preferably consists of an electric insulating material to maintain an electrical separation of the electrodes16,17and so forth when the electrodes16,17of the piezoelectric/electrostrictive element14are directly supported thereby, and leads and lead terminals that are connected thereto, etc. are formed on a surface of the vibrating member18.

Specifically, the member consisting of a highly heat resistant metal or porcelain enamel or the like in which a surface of the metal is coated with ceramics such as glass, or the member consisting of ceramics or the like may be employed. Among them, the member consisting of ceramics is preferable.

Ceramics constituting the vibrating member18may include, for example, stabilized zirconium oxide, aluminum oxide, magnesium oxide, mullite, aluminum nitride, silicon nitride, glass, and so forth. Among these, stabilized zirconium oxide is preferable since it has high mechanical strength, toughness and little chemical reaction to a piezoelectric/electrostrictive layer and electrodes. Furthermore, it is preferred that the stabilized zirconium oxide contains aluminum oxide at 0.1 to 5 mole %.

The stabilized zirconium oxide includes stabilized zirconium oxide and partially stabilized zirconium oxide. The stabilized zirconium oxide is distinguished from zirconium oxide that often generates cracks during a phase transformation between monoclinic crystals and tetragonal crystals at around 1000° C., since it has a cubic crystal structure or the like and does not generate the phase transformation.

The stabilized zirconium oxide may include ones that contain a stabilizer such as calcium oxide, magnesium oxide, yttrium oxide, scandium oxide, ytterbium oxide, cerium oxide or rare earth metal oxides at 1 to 30 mole %. In order to improve the mechanical strength of a vibrating member, stabilized zirconium oxide containing yttrium oxide is preferable. In this case, yttrium oxide is preferably contained at 1.5 to 6 mole %, or more preferably 2 to 4 mole %.

Additionally, a crystal phase of ceramics constituting the vibrating member18may be a mixed phase of cubic crystals and monoclinic crystals, a mixed phase of tetragonal crystals and monoclinic crystals, a mixed phase of cubic crystals, tetragonal crystals and monoclinic crystals, and so forth. Among them, a tetragonal crystal phase, or a mixed phase of tetragonal crystals and cubic crystals is preferable in consideration of strength, toughness and durability.

When the vibrating member18is made of ceramics, the member is composed of a plurality of crystal grains. The average size of the crystal grains is preferably 0.05 to 2 μm, or more preferably 0.1 to 1 μm, to improve the mechanical strength of the vibrating member18.

Subsequently, the fixing member19will be explained. The fixing member19in the present invention fixes at least one part of the vibrating member18so as to vibrate the vibrating member18.

The fixing member19preferably consists of ceramics, but may be the same or different ceramics from the material of the vibrating member18. There may be employed, for instance, ceramics such as stabilized zirconium oxide, aluminum oxide, magnesium oxide, titanium oxide, mullite, spinel, aluminum nitride, silicon nitride, glass, or the like. Among them, a ceramic material having zirconium oxide as a main component, a ceramic material having aluminum oxide as a main component, or a ceramic material having a mixture thereof is more preferable.

Although clay or the like is sometimes added as a firing (sintering) aid when the vibrating member18or the fixing member19is made of ceramics, it is preferable that a component that is likely to be vitrified, such as silicon oxide and boron oxide, is not contained in the ceramics excessively. An excessive amount of a component that is likely to be vitrified is advantageous in joining to the piezoelectric/electrostrictive element14. However, it becomes difficult to maintain a composition of a predetermined piezoelectric/electrostrictive layer because of promotion of reaction between the vibrating member18and a piezoelectric/electrostrictive layer upon being fired, thus resulting in the decrease in element characteristics. Specifically, it is preferable to adjust a percentage content of a material that is likely to be vitrified, such as silicon oxide and boron oxide, in a substrate, at less than 3 wt. %, or more preferably less than 1 wt. %.

It is preferable that the vibrating member18and the fixing member19are integrated to constitute the substrate20consisting of ceramics. Furthermore, a recessed portion20ashown in FIG.1and the like or a hollow portion20bshown in FIG.2and the like (hereinbelow sometimes referred to as recessed portion20aand the like for convenience of explanation) is preferably formed with giving the vibrating member18a thin structure. However, it is not necessarily required to constitute the vibrating member18and the fixing member19integrally. The fixing member19made of a metal, for instance, stainless steel, iron and so forth, may fix the vibrating member18made of ceramics. In this case, there may be employed a method where a surface of the vibrating member18is metallized and the obtained metallized layer is joined to the fixing member19by brazing, or the like.

In addition, in an optical switch without a vibrating member as a substrate as shown inFIG. 10, the substrate is preferably constituted with a material having the same component as a piezoelectric/electrostrictive layer. It is more preferable that the substrate has the same component and the same composition. A substrate of such a material can easily be bonded unitarily with a piezoelectric/electrostrictive layer.

There is no particular limitation on a shape of the recessed portion20a, or the like, formed in the substrate20. The recessed portion may be, for instance, circular, elliptic, or polygonal such as square and rectangular, or the combination thereof. However, in case of a polygonal shape, the corners are preferably trimmed in a round ridge.

In the case that it is constituted as the recessed portion20a, there is no particular limitation on its thickness (height), and it may be thick or thin. Though the thickness is generally determined according to an object of use of the hollow portion, it is preferable that it is thin without having higher thickness than it needs for functioning of the actuator portion. Particularly when it is constituted as a hollow portion, the thickness is preferable about the size of a displacement of an actuator portion to be used. By such a constitution, bending of the vibrating member is limited by a bottom portion of the hollow portion adjacent to the vibrating member in the direction of bending, and thereby the vibrating member is effectively prevented from being destroyed against application of unintended external force. It is also possible to stabilize displacement of the actuator portion at a specified amount by making use of the effect of the limitation of bending. Further, since a thickness of the actuator portion itself is decreased to make bending rigidity small; warpage or the like of the actuator portion itself is effectively corrected upon bonding/fixing the actuator portion to a light transmission portion, which can improve reliability in bonding/fixing. In addition, a volume of raw material can be reduced upon production. Thus, the constitution is advantageous also in view of production cost as well as in planning to lighten the actuator portion.

Specifically, the hollow portion20bpreferably has a thickness of 3-50 μm, more preferably 3-20 μm.

As a method of forming the substrate20by sintering the vibrating member18and the fixing member19for integration, a method of laminating layers such as a green sheet or a green tape by thermo compression bonding and subsequently sintering the layers, or the like, may be employed.

A method of forming the recessed portion20aor the like with giving the vibrating member18a thin structure may be: A method of preliminarily providing a through-hole in a predetermined shape so as to form the recessed portion20aor the like in a second layer before lamination in case of laminating, for instance, two green sheets or green tapes. A method of providing the recessed portion20aby machining such as grinding, laser machining, punching by press machining, etc., in a molded body obtained by pressure molding with a mold, casting, injection and so forth; or the like.

Moreover, in the optical switch of the present invention, it is preferable that the light transmission portion1and the substrate20are fixed with a distance between the light transmission portion1and the optical path-changing portion8by arranging a clearance forming member45on the substrate20as shown in FIG.12. In this case, as shown inFIG. 11, the clearance forming member45may be formed on an entire surface of the substrate20, except for a region where the piezoelectric/electrostrictive element14is arranged. However, the member is preferably formed in patterns so as to equalize a distance between the light transmission portion1and the optical path-changing portion8.

The optical switch in the present invention may contact or separate (off-contact) a single optical path-changing portion8from the light transmission portion1by displacement of a single actuator portion11described above, but the switch may contact or separate a single optical path-changing portion8from the light transmission portion1by displacement of a plurality of the actuators11.

4. Multichannel Optical Switch

A multichannel optical switch according to the present invention is a multichannel optical switch provided with a plurality of optical switches each comprising at least a light transmission portion, an optical path-changing portion and an actuator portion. The light transmission portion has a light reflecting plane provided on at least one part of a plane facing the optical path-changing portion to totally reflect light, and light transmission channels having optical wave guiding bodies and being provided in at least three directions with the light reflecting plane as a starting point The optical path-changing portion is positioned in proximity to the light reflecting plane of the light transmission portion in a movable condition and has an optical path-changing member for at least reflecting or scattering light. The actuator portion has a mechanism that is displaced by external signals and transmits the displacement to the optical path-changing portion. The switching or dividing of an optical path is carried out by contacting or separating the optical path-changing portion to or from the light reflecting plane of the light transmission portion by displacement of the actuator portion in response to the external signals. An optical path where the input light from the light transmission channels is totally reflected at the light reflecting plane of the light transmission portion and it is transmitted to a specific light transmission channel on an output side when the optical path-changing portion is separated from the light reflecting plane of the light transmission portion. Additionally, an input light from the light transmission channel can be reflected or scattered at the optical path-changing portion, and transmitted to a specific one or more light transmission channel(s) on the output side when the optical path-changing portion is contacted to the light reflecting plane of the light transmission portion.

Each component of the multichannel optical switch in the present invention is the same as those already mentioned for the optical switches. Accordingly, the description of each component is omitted herein, and specific embodiments of multichanneling will be shown.

In the present specification, “multichannel” indicates that there are a plurality of locations where optical switching is performed by switching an optical path between a light reflecting plane of the aforementioned light transmission portion and a light reflection member of an optical path-changing portion. The so-called “multichannel optical switch” herein includes the ones in which each component is shared between optical switches.

One embodiment in the present invention may include a multichannel optical switch in which a plurality of optical switches shown in, for instance,FIG. 1toFIG. 3are arranged in a row as in FIG.12. The multichannel optical switch performs optical switching in which an optical path of the light input to one input-side light transmission channel2is optionally switched and the light is transmitted to two or more output-side light transmission channels4,5. Or, the multichannel optical switch performs optical switching in which an optical path of each light input to two or more input-side light transmission channels2,3is optionally switched and the light is transmitted to one output-side light transmission channel4. Such a multichannel optical switch has advantages in that the structure is simple and multichanneling is easy.

An input side and an output side are distinguished simply in relation to the traveling direction of light. Even in the same configuration, input and output are differently termed by reversing a traveling direction.

Another embodiment in the present invention may include a multichannel optical switch formed with each light transmission channel2ato2c,4ato4c,5ato5cin a plurality of optical switches in a single light transmission portion1as shown in FIG.13. It is preferable that each light transmission channel2ato2c,4ato4c,5ato5c, is formed as an optical waveguide since the light transmission channels2ato2c,4ato4c,5ato5ccan be mutually arranged in proximity in such a multichannel optical switch. Also, each light transmission channel in a plurality of optical switches is mutually crossed so as to share a part of each light transmission channel2ato2c,4ato4c,5ato5c, thus greatly miniaturizing and integrating an optical switch.

Furthermore, as shown inFIGS. 14 and 15, another embodiment of the present invention may be a multichannel optical switch in which a plurality of optical switches51are constituted by a plurality of optical switches having one input channel2ato2cand a plurality of output channels4ato4c,5ato5c, and one output channel4a,4b,4cis linked with an input channel2a,2b,2crespectively between adjacent optical switches51, to perform switching of the light input from an input end portion of one optical switch in each optical path-changing portion of a plurality of optical switches including the optical switch.

The multichannel optical switch shown inFIG. 14has an advantage in that signal loss is small in light transmission since light transmission channels2a,2b,2c,4a,4b,4care composed of an optical waveguide. On the contrary, the multichannel optical switch shown inFIG. 15has an advantage in that design is simple since the light transmission portion as a whole is composed of an optical wave guiding body of the same material (the optical waveguide is excluded) and, in an essential sense, specific light transmission channels2ato2c,4ato4c,5ato5care formed.

In these multichannel optical switches, an optical path of the light input from an input end43is switched at each optical path-changing portion8a,8b,8c(not shown inFIG. 15) of a plurality of optical switches. The light is emitted from an output end44a,44b,44cand transmitted to an external signal channel.

Further, as shown inFIG. 16, another embodiment of the present invention may be a multichannel optical switch where a plurality of optical switches51join one output channel4a,4bwith input channel2b,2c, respectively, between adjacent optical switches51by an optical fiber6to perform switching of light input from input end of at least one optical switch in an optical path-changing portion of a plurality of optical switches.

According to this multichannel optical switch, similarly to the multichannel optical switch shown inFIG. 15, since the light transmission portion as a whole can be composed of an optical wave guiding body of the same material (the optical waveguide is excluded), it is easily designed. In addition, since optical transmission is performed with an optical fiber, the multichannel optical switch is more advantageous in suppressing divergence of light in comparison to that shown in FIG.15.

In this multichannel optical switch, it is preferable to unitarily form the light transmission portion1of each optical switch51in view of simplifying the design. However, the multichannel optical switch may be the one in which each optical transmission portion1of the optical switches51is independently formed.

Furthermore, another embodiment of the present invention may include a multichannel optical switch in which a plurality of the multichannel optical switches shown inFIGS. 14to16described above are arranged in a row as shown in FIG.17.

This multichannel optical switch has an advantage in that a large-scale multichanneled optical switch may be easily manufactured since a plurality of light-signal input ends and/or light-signal output ends may be easily provided, and the size is easily reduced since the configuration is simple.

Furthermore, another embodiment of the present invention may include, as shown inFIGS. 18,25, a multichannel optical switch in which optical couplers36a,36b,36care joined to output ends44a,44b,44cof each light transmission channel in the above-noted multichannel optical switch shown inFIGS. 14to16, and at least one part of light transmission channels (not illustrated) is collected. The multichannel optical switch has an advantage in that input and output signals are optionally selected and light is switched to an optional signal channel since output ends44a,44b,44cmay be shared.

In addition to the structure in which optical couplers36a,36b,36care joined to output ends44a,44b,44c, or the like, a structure in which the optical couplers are joined to an input end43becomes an optical divider wherein an optical switch by which the same light signal branches off and is transmitted to any destination is obtained. As optical couplers36a-36cor optical dividers, the light transmission channels can be collected at one point as shown in FIG.18. Another embodiment is where each of light joining channels37a-37cjoin the light transmission channels38a-38cat a plurality of points in an oblique direction. However, as shown inFIG. 26, in the multichannel optical switch shown inFIG. 25, it is preferable to dispose a substrate39provided with a groove corresponding to each of the light transmission channels38a-38cso that the groove may correspond to each of the light transmission channels38a-38c. Since a plurality of light transmission channels can be disposed with high accuracy at a predetermined pitch by disposing the substrate39in such a manner, joining between each multichannel optical switches or between a light source and a multichannel optical switch becomes easy.

Further, in the present invention, a structure in which an optical demultiplexer or an optical multiplexer is connected with the input end43or the output end44may be employed. By such a structure, an optical switch is created by which a plurality of light signals having various wavelength demultiplexed or multiplexed, and each light signal is transmitted to any channel.

Furthermore, another embodiment of the present invention may include, as shown inFIG. 19, a multichannel optical switch having a plurality of multichannel optical switches41shown inFIGS. 14-16. In the multichannel optical switch, each multichannel optical switch41is arranged so that each output end in each multichannel optical switch, for instance, at least one part of44a,44b,44cis positioned in an arc with an input end of the external light transmission channel53disposed independently from the each multichannel optical switch41as a center.

This multichannel optical switch also can transmit light output from each output end of a plurality of multichannel optical switches to a common light transmission channel as the multichannel optical switch shown inFIG. 18described above. This optical switch particularly has such an advantage that no signal loss at jointed parts is generated or minimized since it does not require jointing of light transmission channels by physical means.

In this multichannel optical switch, each multichannel optical switch41may be disposed in various positions according to the purpose and use. For example, as shown inFIG. 19, each of output ends44a,44b,44cdisposed at the same position among each output end in each multichannel optical switch may be positioned in an arc with an input end of the external light transmission channel53in the center. For example, only one output end44ain each output end may be positioned in an arc with an input end of the external light transmission channel53in the center.

In this multichannel optical switch, as shown inFIG. 19, it is preferable to dispose a lens7in each of the output ends44a,44b,44cto suppress divergence of light emitted from each of the output ends44a,44b,44c. Further, it is also preferable that the lens7is disposed in an input end of the external light transmission channel53depending on the external light transmission channel53to be employed.

Furthermore, another embodiment of the present invention may include, as shown inFIG. 20or27, a multichannel optical switch in which each output end44of a plurality of multichannel optical switches41shown inFIGS. 14-16described above, and a plurality of input ends43a,43b,43cin another identical multichannel optical switch42are linked.

Like the multichannel optical switches inFIGS. 18,19described above, this multichannel optical switch transmits the light output from each output end of a plurality of various multichannel optical switches. However, since this optical switch constitutes an optical transmission channel by directly connecting each optical-signal input end or optical-signal output end of each multichannel optical switch, the multichannel optical switch has such advantages in that the miniaturization is easy, and so forth.

As a means for directly connecting each optical-signal input end or optical-signal output end of each multichannel optical switch, an optical fiber46shown inFIG. 20or the like is preferable in the point of less light loss. Alternatively, a ball lens47may be employed as shown in FIG.27. However, when the ball lens47is used for the connection, it is necessary to adjust both the angle of incidence and the refractive index. In addition, it is preferable to amplify light with arranging a light amplifier or the like because light loss is relatively large in principle.

As still another embodiment of the present invention, there may be employed a multichannel optical switch which has a plurality of multichannel optical switches41and an optical waveguide substrate48provided with a plurality of optical waveguides49a-49fin a groove in a substrate body48aand where each output end (not illustrated) of each multichannel optical switch41is communicated with each of the optical waveguides49a-49fof the optical waveguide substrate48.

Since an aperture area can be made large by adjusting a depth or a width of the groove in the optical waveguide substrate48in this multichannel optical switch, the switch can be easily connected to a signal source (light source) such as a laser or an LED, or to a fiber. However, although the connection becomes easy, light loss is relatively large due to the variations of angle of incidence and outgoing light. Therefore, it is preferable to dispose a light amplifier for use in long-distance communications.

The optical waveguide substrate48may be structured so that a substrate48aprovided with grooves having a relatively deep depth arranged at a predetermined pitch is constituted as a clad and that an optical waveguide core50bis formed with a transparent resin or the like. It is also preferable that a clad layer is formed with a material having a slightly lower refractive index than a material for the optical waveguide core on the surface of the groove and that of the optical waveguide core of transparent resin or the like is provided independently in the groove. Such a structure enables the use of various materials such as resin, metal, glass and ceramics as a material for the substrate and/or the optical waveguide clad. In addition, it is needless to say that a material for the substrate has higher refractive index than a material for the clad in such a structure so that a light loss becomes small in such a structure. In connecting a multichannel optical switch41with an optical waveguide substrate48, they may directly contact each other besides the aforementioned optical fiber, ball lens and the like.

Further, as another embodiment of the present invention, there may be employed a multichannel optical switch in which a plurality of optical switches51are structured by at least one optical switch51having a plurality of input-side channels2ato2cand3ato3cand at least one optical switch52having a plurality of output-side channels4ato4cand5ato5cas shown in FIG.21. One output-side light transmission channel4ato4cis communicated with one input-side light transmission path2ato2ebetween adjacent optical switches51, and light input from input end43ato43dof a plurality of optical switches51is switched in an optical path-changing portion8ato8fof a plurality of optical switches51.

Furthermore, in this multichannel optical switch, each of optical path-changing portions8ato8fhas a light reflection member having at least two kinds of light reflection angles (InFIG. 21, the light reflection plane8ato8cand8dto8famong the light path-changing portions8ato8fis indicated, and light reflection angles which are mutually line-symmetrical (e.g., relation of 30° and 150°) among the light path-changing portions8ato8f. For instance, the light that is input from the input terminal43aproceeds to a light transmission channel to the optical path-changing portions8dto8fwhen the optical path-changing portions8a,8b,8care separated from the light transmission portion1. In the optical path-changing portion8din contact with the light transmission portion1, the optical path is switched to the light transmission channel5ato the output end44a, and the light is transmitted from the output end44ato an external light transmission channel. On the other hand, for instance, in the condition that the optical path-changing portion8ais brought into contact with the light transmission portion1, an optical path of the light input from the input end43bis switched to the light transmission channel4atoward the optical path-changing portion8b. The light is similarly transmitted to the light transmission path5ato5ctoward any of the output ends44ato44dcorresponding the optical path-changing portions8dto8fin any of the optical path-changing portions8dto8fwhich is brought in contact with the light transmission portion1, and transmitted to the external light transmission channel from any of the output ends44ato44d.

Thus, since this multichannel optical switch achieves a M×N type optical switch in which each light input to a plurality of input ends43ato43din one light transmission portion1is transmitted to arbitrary one of output ends of44ato44dby the operating condition of a plurality of optical path-changing portions, the multichannel optical switch has an advantage in that it is very profitable in trying miniaturization and high integration. However, the multichannel optical switches shown inFIGS. 17to19can input light signals from each input end43and process each light signal in parallel. On the other hand, in this multichannel optical switch, a slight time difference is required to input light signals to each light input end43(43ato43d).

Yet another embodiment of the present invention is a multichannel optical switch which is constituted by a plurality of optical switches51including one or more optical switch(s)51having at least an optical path-changing portion8provided with a light scattering body10f, as shown inFIG. 29, and where one output-side light transmission channel4a,4bis communicated with one input-side light transmission channel2b,2cwith an optical fiber6with an optical amplifier54being interposed therebetween. Light input from the input end in at least one optical switch is divided to numerous light transmission channels at an optical path-changing portion of one or more optical switch(s) to perform switching.

In this multichannel optical switch, light21input from a light transmission channel2ais totally reflected at a light reflecting plane1aof the light transmission portion1and transmitted to a light transmission channel4aand further to a light transmission channel2bin an optical switch where an optical path changing portion8is under a separated condition. On the other hand, in an optical switch where the optical path changing portion8is under a contact condition, light introduced from a light transmission path2bis taken to an optical path-changing portion, scattered by a light scattering body10f, and divided to light transmission channels4band5b. Though the divided light is attenuated because of the division at this time, the light is amplified with an optical amplifier when the light is transmitted to a transmission channel ahead, and the attenuated light is complemented; and thereby the optical signal is transmitted with being hardly attenuated even though the light passes a plurality of optical switches. The optical amplifier may be a semiconductor laser diode type, a fiber type, or the like.

Though a multichannel optical switch of the present invention is explained with the intention of optical communication mainly, application for an optical printer is hereinbelow described as an applied embodiment.

FIG. 22is an explanatory view schematically showing an embodiment where a multichannel optical switch of the present invention is applied to an optical printer.

As shown inFIG. 22, in this optical printer, the afore-mentioned multichannel optical switch41is adapted as a printer head61. This optical printer is provided, as basic elements, with the printer head61consisting of the multichannel optical switch41, a lens63collecting the light21output from each output end44, and a photosensitive dram62forming a latent image by the light21collected by the lens63.

In such an optical printer, a structure in which a laser light source is disposed in a shape of an array substantially may be employed. Therefore, optical parts such as a polygon mirror and a lens annexed to the polygon mirror like a conventional laser printer may be omitted and thereby a sharp minimization and decrease in cost by reducing the number of parts can be planned.

In addition, this optical printer is not the one that forms a latent image by light output from each light source disposed at every desired dot like a LED printer, but the one that forms a latent image by light output from each output end being switched and the light from the same light source at every output end disposed in accordance with every dot. Therefore, this optical printer does not have unevenness in quantity of light in each dot and does not cause a problem of decrease in quantity of light due to a temperature rise upon long-time use.

Further, this optical printer is made to be an optical printer having a desired resolution by suitably adjusting intervals for arranging each output end44of a multichannel optical switch41constituting the printer head61.

The present invention was explained above in detail based on some embodiments, but the interpretation of the present invention should not be limited to the above-mentioned embodiments. Without departing from the scope of the invention, based on the knowledge of persons skilled in the art, variations, modifications, improvements, and so forth may be added. There may be further provided an optical switch which enables to switch every specific input light and is suitable for an optical communication system.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, there is provided an optical switch that solves conventional problems of optical switches, consumes little power and, at the same time, allows high-speed response, size reduction, high integration, and reduction of signal attenuation, and further an optical switch suitable for an optical communication system, an optical storage device, an optical arithmetic unit, an optical recorder, an optical printer and so forth, and capable of switching for each specific beam.