Abstract:
An optical switch has an input section for inputting a light beam and movable optical members each comprised of a piezoelectric actuator for inputting the light beam from the input section and for individually switching an optical path of the light beam. Each of the piezoelectric actuators has a piezoelectric body for undergoing oscillating movement and a movable body frictionally driven by oscillating movement of the piezoelectric body. A driving control device drives the piezoelectric bodies of the piezoelectric actuators and controls positions of the piezoelectric bodies to switch the optical path of the light beam. An output section outputs the light beam from the piezoelectric actuators.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical switch used in, for example, an optical network of a high-density light wavelength multiplex system and to a method of controlling the same and, more particularly, to a compact multifunctional optical switch and a method of controlling the same. 
     2. Description of the Related Art 
     In recent years, with rapid spread of the internet or the like, a communication transmitting system is shifting to a system using an optical fiber. Further, with an object of higher density formation of transmission capacity, there is being adopted a WDM (Wavelength Division Multiplexing transmission system using optical multiplexing conversion. In order to adopt the WDM system, an optical control communication module for synthesizing/dividing, switching, or attenuating optical signals having different wavelengths becomes indispensable. 
     As conventional examples of an optical switch for switching light, there are technologies disclosed in, for example, Japanese Patent Laid-Open No.301812/1992 and Japanese Patent Laid-open No.264415/1992. The former optical switch is constructed by a constitution in which waveguides are formed in a shape of a lattice, slits are provided at intersections of the waveguides, mercury, silicone and air are movably interposed at the slits and mercury or silicone interposed at the waveguides are switched by heating these to move to thereby control light. The latter switch is constructed by a constitution in which communicating tubes are provided at intersections of waveguides, a liquid is filled (sealed) in the communicating tubes while constituting gaps and sizes of the gaps are adjusted by heating the liquid and vaporizing portions thereof to thereby control light. 
     However, according to the above-described two optical switches, the waveguides, the slits and the gaps must be formed (arranged) accurately. Furthermore, mercury or the like or the liquid must be sealed. Accordingly, there poses a problem that fabrication of the optical switches is difficult. 
     Further, the temperature of mercury or the like or the liquid needs to be controlled accurately and, accordingly, the size of supplementary mechanisms other than the main body of the optical switch, such as heating mechanism, a temperature sensor and a control mechanism thereof, become large. Furthermore, the number of parts is also increased. That is, the optical switch cannot be made compact, and fabrication thereof is complicated. 
     It is an object of the invention to provide an optical switch which is compact and has high productivity and to provide a method of controlling the optical switch. 
     SUMMARY OF THE INVENTION 
     In order to resolve the above-described problems, an optical switch according to the invention characterized in comprising an input section for inputting a light beam, optical parts each having an optical path changing characteristic movable to a position of blocking the light beam of specially selected wavelength outputted from the input section, output sections provided respectively in correspondence with a case in which the optical path is not changed by the optical parts, driving means for separately driving the optical parts, and driving control means for controlling to arrange the optical parts via the driving means and selecting the output sections constituting output destinations of the light beam. The optical switch can be made compact since a temperature sensor or the like is not. Furthermore, productivity is increased since there is not a member which needs fine fabricating steps as in a conventional member such as a waveguide or the like. 
     Here, there may be constructed a constitution comprising a plurality of the optical parts in a series direction relative to the light beam and comprising the output sections in correspondence with respectives of the optical parts, and there may be constructed a constitution comprising a plurality of the input sections in a parallel direction and comprising the optical parts in correspondence with respectives of the light beams of specially selected wavelength from the input sections. 
     As a most general constitution, there is exemplified a constitution comprising two of the input sections in a parallel direction, comprising two of the output sections in the parallel direction at positions opposed to the input sections and comprising two of the optical parts for determining the output destinations of the light beams of specially selected wavelength for the respective light beams. In the case of constructing the constitution, a further large-scaled optical switch can be constituted by connecting a plurality of the optical switches, for example, in a shape of a matrix. 
     Further, in the case of providing a plurality of the driving means, although it is necessary to widen an interval between the optical parts such that front and rear ones of the optical parts and the driving means do not interfere with each other, when the front and rear ones of the driving means relative to the light beam are arranged in a zigzag shape between the same optical parts, the interval between the optical parts can be narrowed. That is, the optical switch can be made further compact. 
     In this case, when there is constructed a constitution in which the moving optical members integrating the driving means to the optical parts are arranged in a zigzag shape such that the driving means are disposed between the same optical parts interposing the light beam, the productivity in assembling is promoted. 
     Further, as the driving means, for example, there is used a piezoelectric actuator. In this case, when there is constructed a constitution comprising a piezoelectric body producing an elongating and contracting oscillation and a moving body frictionally driven by the elongating and contracting oscillation produced to the piezoelectric body, the optical switch can further be made compact since there is constituted the driving means which is compact and having high torque More specifically, there is used a piezoelectric actuator of a rotational type or a linear type. 
     Further, when the driving means is a piezoelectric actuator, the following constitution can be constructed. 
     First, the control means may be constructed by a constitution of inputting a preparatory signal before driving operation. In this case, the piezoelectric actuator is warmed up by the preparatory signal to thereby improve response performance and accordingly, the response of the optical switch can be promoted. 
     Further, when the control means is constructed by a constitution having a self-excited oscillating circuit, the piezoelectric actuator can be driven more efficiently. 
     Further, when there is provided a support member for movably supporting the optical part and the control means is provided to the support member, a space is effectively utilized and the optical switch can further be made compact. 
     Further, in the above-described optical switch, when the plurality of optical parts are controlled to drive simultaneously, a time period necessary for switching the optical parts can be shortened. That is, the response of an optical communication apparatus is enhanced. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing a constitution of an optical switch according to a first embodiment of the invention. 
     FIG. 2A is an outline view of a section of the optical switch of FIG.  1  and 
     FIG. 2B is an outline view of an upper face of the same. 
     FIG. 3 is a block diagram showing a constitution of a moving optical member of FIG.  1 . 
     FIG. 4 is a block diagram showing an example of a drive circuit of FIG.  1 . 
     FIG. 5 is a view of essential portions of an optical switch according to a second embodiment of the invention. 
     FIG. 6 illustrates views showing a constitution of an optical switch according to a third embodiment of the invention in which 
     FIG. 6A is a front view of essential portions and 
     FIG. 6B is a top view. 
     FIG. 7 illustrates views showing a constitution of an optical switch according to a fourth embodiment of the invention in which 
     FIG. 7A is an outline view of a vertical section, 
     FIG. 7B is an outline view of an upper face of the same and 
     FIG. 7C is an outline view of a side face. 
     FIG. 8 is a block diagram showing a constitution of an optical switch according to a fifth embodiment of the invention. 
     FIG. 9 is an outline plane view of the optical switch of FIG.  8 . 
     FIG. 10 is a block diagram showing a constitution of an optical switch according to a sixth embodiment of the invention. 
     FIG. 11 is a block diagram showing an application example of the optical switch of FIG.  10 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     (First Embodiment) 
     First, an explanation will be given of an outline constitution in reference to a block diagram. 
     As shown by FIG.  1  and FIGS. 2A and 2B, an optical switch  1  is generally constituted by an input section  10  for inputting a light beam  100 , a plurality of moving optical members  20  for bending a specially selected wavelength light beam of inputted the light beam  100  substantially by 90°, a driving control means  30  for controlling positions of the respective moving optical members  20 , and a plurality of output sections  40  constituting output destinations of the light beam  100 . That is, the optical switch  1  is an optical switch for determining a progressing direction of the light beam  100  inputted from the input section  10   b  the moving optical member  20  and thereafter outputting the light beam  100  from the output section  40 . 
     Here, as shown by FIG. 2B, the moving optical members  20  are arranged in series relative to the light beam  100  when the light beam  100  advances straight. Further, the output section  40  outputs the light beam  100  when the light beam  100  advances straight. Further, the output section  40  outputs the light beam  100  when the progressing direction is changed by the moving optical member  20 . Therefore, the output sections  40  are respectively provided for whether the moving optical members  20  change the progressing direction of the light beam  100 . 
     As shown by FIG. 2B, the input section  10  is provided with an optical fiber  10   a  and a lens  10   b . The output section  40  is also provided with an optical fiber  40   a  and a lens  40   b  similarly. 
     The moving optical part  20  is constituted by an optical part  21  and an ultrasonic actuator  22  and controls an optical signal by moving the optical part  21  to a position of blocking the optical signal or removing the optical part  21  from a blocking position by the ultrasonic actuator  22 . As shown by FIG. 2A, the moving optical member  20  is attached to a side face of a support member  20   a  (illustration of which is omitted in FIG.  2 B). 
     The optical part  21  is, for example, a slit or a mirror for refracting or reflecting the light beam  100  to thereby bend an optical path thereof substantially by 90° when the optical part  21  is arranged at a position of blocking the light beam  100  and outputting the light beam  100  from a corresponding one of the output section  40 . Further, the optical part  21  can be constituted not only by a single part but also by a plurality of parts. For example, in FIG. 2, the optical part  21  is constituted by an optical member  21   a  having a function of changing the optical path and an optical member  21   b  having at least one characteristic in optical characteristics of transmitting wavelength, absorbing wavelength, optical amount, phase and so on and can simultaneously change the optical path and control light. 
     The ultrasonic actuator  22  is, for example, a piezoelectric actuator of a rotational type and is generally constituted by a piezoelectric element  22   b  in a shape of a circular disk fixed above a fixed base  22   a , an oscillator  22   c  provided integrally with the piezoelectric element  22   b , a moving body  22   d  mounted on the oscillator  22   c  and pressing means  22   e  for ensuring contact pressure between the oscillator  22   c  and the moving body  22   d  as exemplified in FIG.  2  and FIG.  3 . Bending oscillation produced at an upper face of the piezoelectric element  22   b  is amplified by the oscillator  11   c  and is outputted from a projection (not illustrated) on the oscillator  11   c  to the moving body  22   d  as drive force. Further, the moving body  22   d  fixedly holds the optical part at one end thereof. 
     Here, the moving body  22   d  of the ultrasonic actuator  22  is formed in a rod-like shape and is rotated with a vicinity of the center as a rotational shaft. Further, the moving body according to the invention may be constituted by a plurality of members in accordance with its use. 
     Further, at the side face of the support member  20   a , there are provided two projections  20   b  on a rotational circumference of other end of the moving body  22   d  to sandwich the other end. That is, a pivoting range of the moving body  22   d  is restricted by the two projections  20   b . One of the projections  20   b  is installed such that the optical part  21  provided at the one end of the moving body  22   d  is disposed at a location of blocking the light beam  100  at a vicinity of a side end of the support member  20   a  and other of the projections  20   b  is installed such that the moving body  22   d  as well as the optical part  21  are disposed at an escaping position constituting a location at which the optical part  21  does not interfere with the light beam  100 . Further, by such structure, primary moment of the moving body  22   d  can be reduced. 
     As shown by FIG. 1, the driving control means  30  is constituted by, for example, a drive circuit  31  and control means  32 . 
     Among them, the drive circuit  31  is a well-known self-excited oscillation circuit exemplified in FIG. 4 for amplifying a periodic voltage variation between two faces of the piezoelectric element  22   b  produced by piezoelectric oscillation and using the periodic voltage variation as a drive signal of the piezoelectric element  22   b  per se. The drive circuit  31  is formed, for example, by IC and is attached on a base plate  1   a  of the optical switch  1 . 
     Here, an inverted amplifier  31   a  and an amplifier  31   b  in the drive circuit  31  are controlled by the control means  32 . Thereby, the ultrasonic actuator  22  is controlled by the control means  32 . 
     Further, the control means  32  moves to rotate the respective optical parts  21  by controlling the ultrasonic actuators  22  and at this occasion, in order to shorten a switching time period, a new one of the optical part  21  is arranged to a position of blocking the light beam  100  and at the same time, the optical part  21  arranged at the position of blocking the light beam  100  is returned to the escaping position. 
     Further, the control means  32  inputs a preparatory signal to the ultrasonic actuator  22  before moving to rotate the optical part  21  by actually driving the ultrasonic actuator  22 . By inputting the preparatory signal, the ultrasonic actuator  22  is brought into a warmed-up state and response in inputting the drive signal for actually driving the ultrasonic actuator  22  is promoted. 
     Here, as the preparatory signal, there is a drive signal in a direction opposed to a direction of actually driving the ultrasonic actuator  22  or a very week drive signal to a degree of not moving the moving body  22   d . In the former case the moving body  22   d  is pressed to the projection  20   b  by the drive force and the moving body  22   d  is not moved. 
     According to the optical switch  1  having the above described constitution, the output section  40  constituting the output destination of the light beam  100  can be switched by pertinently selecting the optical part  21  arranged at the position of blocking the light beam  100  by pertinently controlling the respective moving optical member  20 . That is, the optical switch  1  functions as an optical switch. 
     Further, the optical switch  1  can be made compact since a temperature sensor or the like is not necessary and is not provided with a member which needs conventional fine fabricating steps as in the waveguide and therefore, the productivity is increased. 
     Further, a control state of the light beam  100  can be maintained without operating the ultrasonic actuator  22  by conducting electricity thereto. Accordingly, energy consumption of the optical switch  1  can be reduced. 
     Further, an angle of inputting light beams and outputting light beams are not restricted 90° depend on characteristic of the optical part  21 . And, Other example of the optical part  21  is a prism or a flat plate. Moreover, The moving optical members  20  are arranged conformity by characteristic of the optical part  21  and by a fixed angle to the inputting light beam. 
     (Second Embodiment) 
     The optical switch  1  according to a second embodiment of the invention is generally constructed by a constitution similar to that of the second switch  1  according to the first embodiment. Particularly, as shown by FIG. 5, there is constructed a constitution in which an encoder  23  is provided to the moving optical member  20  without providing the projections  20   b  and the control means  32  is provided with a function of controlling the ultrasonic actuator  22  based on a result of detection from the encoder  23 . 
     The encoder  23  is constituted by slits  23   a  rotated along with the moving body  22   d  and a rotation amount detector  23   b  of a well-known optical type for detecting a rotation amount of the slits  23   a . The result of detection of the rotation amount detector  23   b  is transmitted to the control means  32 . 
     According to the embodiment, not only an effect similar to that of the first embodiment is achieved but also the moving body  22   d  can be controlled by an arbitrary angle, Further, there is not a possibility of causing a drawback accompanied by bringing the projection  20   b  into contact with the moving body  22   d.    
     (Third Embodiment) 
     Although an optical switch  2  constituting a third embodiment of the invention is generally constructed by a constitution the same as that of the optical switch  1 , as shown by FIG. 6A, a moving optical member  50  is used in place of the moving optical member  20 . Further, the drive circuit  31  is provided directly on a main plate  2   a  of the optical switch  2 . 
     As shown by FIG. 6B, the moving optical member  50  is constructed by a constitution in which the optical part  21  is linearly moved in a direction of intersecting with the light beam  100  by an ultrasonic actuator  51  which is a piezoelectric actuator of a linear type. 
     The ultrasonic actuator  51  is provided with a piezoelectric element and an oscillator in a shape of rectangular parallelepiped, amplifies bending oscillation produced at an upper face of the above-described piezoelectric element by the above-described oscillator and outputs the bending oscillation from a projection  51   a  on the oscillator as drive force. 
     Here, the optical part  21  is sandwitched by two stopper members  2   b  erected on the base plate  2   a  and is made movable between the stopper members  2   b.    
     One of the stopper members  2   b  is positioned to be brought into contact with the optical part  21  when the optical part  21  is moved to the position of blocking the light beam  100  and other of the stopper members  2   b  is positioned to be brought into contact with the optical part  21  when the optical part  21  is deviated from the position of blocking the light beam  100 . 
     Further, the preparatory signal by the control means  32  constitutes a very weak drive signal in the optical switch  1  or a signal of driving the optical part  21  in a direction of being brought into contact with the stopper member  2   b.    
     That is, according to the optical switch  2 , there is achieved an effect similar to that of the optical switch  1  by switching the optical part  21  arranged to block the light beam  100  by driving the ultrasonic actuator  51 . 
     (Fourth Embodiment) 
     Although an optical switch  3  constituting a fourth embodiment of the invention is generally constructed by a constitution the same as that of the optical switch  1 , as shown by FIGS. 7A and 7B, there is constructed a constitution in which the moving optical members  20  are arranged by alternately interposing the light beam  100  and the drive circuit  31  is attached to a side face of the support member  20   a , preferably, a side face thereof on a side of attaching the moving optical member  20  with an object of compact formation of the optical switch  3 . 
     The input section  10  is provided on a slightly upper side of the moving optical members  20 . Therefore, the light beam  100  is propagated on a slightly upper side of the moving optical members  20 . 
     Further, the optical part  21  is integrated to the ultrasonic actuator  22  in a direction of bending the light beam  100  in an upper direction. 
     Further, the output section  40  is provided on the upper side of the moving optical member  20 . 
     That is, the light beam  100  is bent in the upper direction by the optical part  21  pivoted in the upper direction and is emitted from the output section  40 . 
     Further, as shown by FIG. 2B, the side faces of the support members  20   a  on the sides of attaching the moving optical members  20  are uniquely determined by to which sides the moving the optical members  20  are disposed relative to the light beam  100  and are opposed to each other by interposing the light beam  100 . Thereby, an interval necessary for installing the moving optical members  20  can be narrowed. 
     Therefore, according to the optical switch  3 , not only an effect similar to that of the optical switch  1  is achieved but also the optical switch  3  can further be compact. 
     (Fifth Embodiment) 
     According to an optical switch  4  constituting a fifth embodiment of the invention, as is generally shown by FIG.  8  and FIG. 9, a plurality of the moving optical members  20  are arranged in a shape of a matrix, further, proximately to contiguous two sides of the moving optical members  20  arranged in the shape of the matrix, the output sections  40  are installed at respective rows or columns of the respective moving optical members  20 , further, the input sections  10  are installed at one of remaining sides thereof for respective rows or columns of the respective moving optical members  20 . 
     That is, as shown by FIG. 9, the optical switch  4  is an optical switch of an M×N type for outputting the light beams  100  imputed from the respective input sections  10  from desired ones of the output sections  40  by pertinently controlling the moving optical members  20  and a single one of the optical switch  4  can deal with the plurality of light beams  100  (that is, optical signals). Therefore, in the case of dealing with a large-scaled network, a space necessary for installing the optical switch can be reduced. 
     (Sixth Embodiment) 
     As shown by FIG. 10, an optical switch  5  constituting a sixth embodiment of the invention is an optical switch having a type the same as that of the optical switch  4  and is of a 2×2 type. 
     According to the optical switch  5 , not only an effect similar to that of the optical switch  4  is achieved but also, as shown by FIG. 11, a further complicated optical switch can easily be constituted by arranging the optical switches  5  in a shape of a matrix in the same directions. That is, optical switches of various types can be fabricated at low cost by constituting basic parts by the optical switches  5  and combining the optical switches  5 . Here, further various types of optical switches can be fabricated by including also the optical switches  4  in the parts. 
     Further, the invention is not limited to the above described respective embodiments but can naturally be changed pertinently within a range not deviated from the gist of the invention also with regard to specific arrangements of constituent elements or the like. 
     For example, there may be constructed a constitution of providing a moving amount of the respective moving body, that is, positional information of the optical part from a power consumption amount and a driving direction of the respective ultrasonic actuator. 
     Further, there may be constructed a constitution of providing the projections  20   b  in the optical switch  1  according to the second embodiment. In this case, there is constructed a constitution in which the moving body  22   d  is positioned by the projections  20   b  and the position of the moving body  22   d  is recognized by the encoder  23 . 
     As described above, according to the optical switch of the invention, the optical switch can be made compact since a temperature sensor or the like is not needed, further, the productivity is increased since there is not a member which needs fine fabricating steps as in a conventional member such as a waveguide or the like.