KR100398803B1 - Optical switch actuated with multiphase driving voltage and having multiple rotation axes - Google Patents

Abstract

The present invention relates to an optical wavelength switch for use in an optical communication network. In the optical wavelength switch of the present invention, four or more pairs of vertical driving electrodes are disposed around the driving layer to rotate the driving layer about a plurality of rotation axes according to the pattern of driving voltage applied to each driving electrode, thereby allowing incident light to be diverted. Can be effectively increased to increase the capacity of a switching system comprising an array of wavelength switch elements. The optical wavelength switch according to the present invention is rotated by the electric attraction force and the repulsive force acting by the driving voltage of the different polarity applied to the upper and lower driving electrodes, the conventional optical wavelength switch using the electrostatic force even when using a relatively low driving voltage High speed operation is possible compared to the device. In addition, the optical wavelength switch of the present invention can relatively reduce the difference between the voltage applied to the drive layer and the vertical drive electrode, thereby preventing defects caused by the discharge phenomenon between the drive layer and the drive electrode.

Description

OPTICAL SWITCH ACTUATED WITH MULTIPHASE DRIVING VOLTAGE AND HAVING MULTIPLE ROTATION AXES}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wavelength switch used to transmit an optical signal in a desired path in an optical communication network. In particular, the present invention relates to a driving layer by applying a multiphase driving voltage to at least four pairs of vertical driving electrodes installed around a driving layer equipped with a micromirror. The present invention relates to an optical wavelength switch capable of setting various optical communication paths by rotating about four or more rotation axes.

Conventionally, in order to establish a communication path of an optical communication network, a method of receiving an optical signal and converting the optical signal into an electrical signal and switching the electrical signal path after switching the electrical signal to an optical signal is used. In this method, the optical signal is converted into an electrical signal and then converted back to an optical signal. Therefore, the transmission efficiency of the optical communication network is degraded and the cost of constructing the network is high. In order to solve this problem, an optical wavelength switch technology has been recently developed to switch an optical signal directly to a desired path without converting the optical signal into an electrical signal. One widely used technique for constructing an optical wavelength switch is to use a micro-electro-mechanical system (MEMS) composed of an array of small mirrors in which the angle of the reflecting surface can rotate at a predetermined angle in response to a drive signal input. . The miniature mirror constituting the MEMS is used to form an optical communication path of a desired shape by rotating by a predetermined angle in response to the input of the drive signal to reflect the incident light input from the input optical fiber to the selected output optical fiber.

Conventional optical wavelength switches in the form of MEMS are typically implemented in the form of cantilever micromirrors and torsion beam micromirrors. The cantilever micromirror has a mirror in the form of a cantilever extending from the base, and the mirror is connected to the base by an elastic flexure to change the path of incident light. The torsion beam micromirror has a structure similar to the cantilever micromirror, except that the mirror is supported by a pair of torsion beams, which are connected to opposite sides of the mirror and are deformed by rotational forces acting on the mirror. Thus, the torsion beam micromirror may change the path of incident light by rotating about one rotation axis formed by a pair of torsion beams according to the type of driving signal applied thereto.

Conventional MEMS light-wavelength switches in the form of cantilever and torsion beams apply a driving voltage to a mirror driving electrode disposed on the base side on which the micromirror is mounted to generate a rotational force of the mirror by using electrostatic force induced by the driving voltage. However, in the conventional optical wavelength switch, only one driving electrode is disposed on one side of the micromirror, thereby overcoming the elastic force of the cantilever and the torsion beam and rotating the micromirror, and also the micromirror for the driving signal according to the demand for high speed optical switch operation. In order to shorten the response time, relatively high voltage should be applied to the driving electrode. However, when a high voltage is applied to the mirror driving electrode, an arc discharge occurs between the micromirror and the driving electrode, so that the rotation angle of the mirror cannot be accurately controlled and the micromirror or the driving electrode is damaged. In addition, when a high voltage is applied to the driving electrode, it takes time to erase the charged charge between the driving electrode and the micromirror when applying a voltage of opposite polarity to the driving electrode to change the angle of the micromirror. The problem of delayed time is issued.

In addition, in the conventional cantilever or torsion beam type MEMS optical wavelength switch, since the micromirror is rotated around only one rotation axis by the driving voltage, the incident light signal cannot be reflected in various paths, thereby limiting the capacity of the optical switching system. There was. Conventional cantilever type MEMS switch elements have only one off state position and one on state position to serve to turn on and off the optical signal. Conventional torsion beam type MEMS switches typically have one off position and two on states. It only has the function of taking the position and selecting two optical signal paths in the on state of the switch. With these switch elements, a switch array including a large number of switch elements must be used to form the number of optical signal paths required by the switching system capacity. Therefore, the structure of the switching system becomes complicated and the manufacturing cost increases. have.

Therefore, in order to solve the problem of the conventional MEMS optical wavelength switch, there is a demand for an optical wavelength switch element capable of operating at a high speed even with a relatively low driving voltage and allowing one switch element to selectively set various optical signal paths. .

According to the present invention, four or more pairs of upper and lower driving electrodes are disposed around the driving layer, and the micromirror is rotated in any direction about a plurality of, preferably four or more rotational axes, according to a pattern of driving voltage applied to the driving electrode. It is an object of the present invention to provide a MEMS type optical wavelength switch device capable of setting various optical communication paths by reflecting an optical signal to various paths, that is, desired output optical fibers. In addition, the present invention is a good response characteristics and durability while applying a relatively low drive voltage to the drive electrode by rotating the drive layer by the electric attraction and repulsive force acting by a pair of drive electrode including the upper drive electrode and the lower drive electrode It is an object of the present invention to provide an optical wavelength switch having a.

1 is an exploded perspective view of an optical wavelength switch according to an embodiment of the present invention.

2 is a perspective view of the optical wavelength switch of FIG.

3 is a cross-sectional view taken along the axis Y of the optical wavelength switch of FIG.

4 is a cross-sectional view of an optical wavelength switch of the present invention in which a driving layer is supported by an elastic beam;

Fig. 5 is a sectional view of the optical wavelength switch of the present invention with the drive layer supported by the pivot support.

6 is a cross-sectional view of the pivot support of FIG.

7 is a perspective view of an optical wavelength switch according to another embodiment of the present invention.

8A is a plan view of an optical wavelength switch according to another embodiment of the present invention.

8B is a cross-sectional view of the optical wavelength switch of FIG. 8A.

<Explanation of symbols for the main parts of the drawings>

10: substrate

11: lower drive electrode

13: upper drive electrode

14: driving layer

17: lattice structure

19: micromirror

The present invention in order to achieve this technical object; A drive layer including a mirror supported on the substrate so as to be rotatable in any direction and reflecting incident light; Each of the four or more driving electrode pairs including a lower driving electrode and an upper driving electrode and disposed around the driving layer, wherein the driving layer is biased to a predetermined potential and the upper driving electrode and the lower driving of the at least one driving electrode pair One of the electrodes provides an optical wavelength switch to which a voltage having the same polarity as the voltage applied to the driving layer is applied and the other to which the voltage having the opposite polarity or a voltage of 0 V is applied. A predetermined voltage is applied to the driving layer, and a driving voltage having the same polarity as the voltage applied to the driving layer is applied to the upper or lower driving electrodes of one driving electrode pair and applied to the driving layer to the other driving electrode. When a driving voltage having a potential different from that of a voltage or a potential of 0 V is applied, and a driving voltage having an opposite pattern is applied to a pair of driving electrodes facing each other with the driving layer interposed therebetween, a driving voltage is generated between the driving layer and the upper and lower driving electrodes. The driving layer can be operated at high speed by the electrical repulsion and attraction force. As a main feature of the present invention, by adjusting a pattern of driving voltages applied to four or more pairs of driving electrodes provided around the driving layer, the driving layers can be rotated around a plurality of, preferably four or more rotational axes.

Hereinafter, with reference to the embodiment of the present invention shown in the accompanying drawings the structure and features of the optical wavelength switch element according to the present invention will be described in detail. 1 is an exploded view of an optical wavelength switch according to an embodiment of the present invention. For the purpose of illustration, FIG. 1 illustrates the components of the optical wavelength switch element in a separated state, but the optical wavelength switch of the present invention uses a method of stacking and etching a semiconductor such as silicon with a sacrificial layer refurbished. It should be understood that it is formed as an integral structure. Methods for processing such MEMS structures are described in MA Michalicek, JH Comtois, and HK Schriner, "Design and fabrication of optical MEMS using a four-level planarized surface-micromachined polysilicon5 process," Proc. SPIE , Vol. 3276, pp. 48-55, 1998, and many other documents are known, so a detailed description will be omitted.

Referring to FIG. 1, a substrate 10 formed of a semiconductor such as silicon is provided, and the lower driving electrode 11 and the upper driving electrode 13 are formed of a semiconductor material such as polysilicon so as to oppose the four portions of the substrate. The lower driving electrode 11 is formed by depositing a metal layer, doping conductive impurities, or using polysilicon in a predetermined region of the substrate. The lower driving electrode is electrically insulated from the substrate and is connected to a power source (not shown) that applies a predetermined driving voltage when driving the switch. The lower end portion 13A of the upper driving electrode 13 is formed in the outer region 12 of each lower driving electrode of the substrate, and the upper end portion of the upper driving electrode 13 can cover the driving layer 14 as described below. 13B is formed. It is preferable that the electrode plate of the upper drive electrode 13 has a shape corresponding to the shape of the lower drive electrode 11. The upper driving electrode may also be formed by doping impurities into the silicon or using polysilicon, but it is preferable to form the upper driving electrode using polysilicon which is easy to selectively etch during the manufacturing process of the switch element. The upper driving electrode 13 is also electrically insulated from the substrate 10, and a power source (not shown) for providing a driving signal of the optical wavelength switch is connected. As described below, the electrode plates 13B of the lower driving electrodes 11 and the upper driving electrodes 13 define the driving layers by the electric force generated when a predetermined voltage is applied to the driving layers and the driving electrodes. It must have enough area to rotate at an angle.

When the four pairs of lower driving electrodes 11 and the upper driving electrodes 13 of FIG. 1 are coupled as shown in FIG. 2, the driving layer 14 is positioned in an inner space defined by each of the lower driving electrodes and the upper driving electrodes. . The drive layer 14 is made of a generally rectangular shape of a semiconductor material such as doped silicon or polysilicon, and legs 15 at each corner of the drive layer support the drive layer between the upper drive electrode and the lower drive electrode. Is formed. In this embodiment, the driving layer is described as being formed in the shape of a rectangular flat plate, but the shape of the driving layer may be variously changed, for example, may be formed in a circular shape as described below. Each leg is formed integrally with the drive layer, usually of the same material as the drive layer. When the switch is at rest, each leg 15 is in contact with an area 16 on the substrate, which is insulated from the substrate 10 and connected to an external power source. The leg 15 also serves to transfer the bias voltage applied from the region 16 to the drive layer 14 when the switch is in operation.

A mirror yoke 18 is formed at the center of the driving layer, and a micromirror 19 is mounted on the mirror yoke so that the micromirror also rotates at the same angle as the driving layer as the driving layer rotates. As shown in FIG. 1, a grating structure 17 including horizontal members and vertical members that cross each other may be formed at the center portion of the driving layer. When the central portion of the drive layer is formed of the lattice structure 17, the mirror yoke 18 and the micromirror 19 are formed at the intersection of the horizontal member and the vertical member. In some cases, only the horizontal member or the vertical member may be formed in the center of the driving layer instead of the lattice structure. The reason for forming the lattice structure or the horizontal / vertical member by patterning the center portion of the driving layer 14 is that the capacitance formed between the upper driving electrode 13, the lower driving electrode 11 and the driving layer inserted between them is formed. In order to more precisely control the electrical force acting between them and to facilitate the etching process of the sacrificial layer located between the driving layer and the substrate when manufacturing the switching device. The thickness and width of the horizontal member and the vertical member formed at the central portion of the drive layer can be appropriately adjusted as long as they are not deformed by the electrostatic force acting on the drive layer 14 during switch operation.

As shown in Figs. 1 and 2, the drive layer 14 is a semiconductor material such as polysilicon, doped silicon, etc. having good electron mobility and is preferably a single layer, preferably a lattice structure, a horizontal member or a vertical member in the center. Is patterned to have The driving layer is supported by the substrate 10 through the legs 15 formed at each corner, and is kept in contact with the upper and lower driving electrodes at a position between the upper driving electrode and the lower driving electrode as shown in FIG. 2. The drive layer is electrically insulated from the substrate, and when the optical wavelength switch operates, a predetermined bias voltage is applied to the drive layer from an external power source as described below. When a different driving voltage is applied to the upper driving electrode 13 and the lower driving electrode 11 while a constant voltage is applied to the driving layer, an electric force is applied between the driving layer and the upper and lower driving electrodes to rotate the driving layer. The micromirror 19 mounted on the driving layer is rotated. When the drive layer is rotated by an electric force acting by the drive electrode, the drive layer may contact the drive electrode, in particular the upper drive electrode. The upper drive electrode or the drive to prevent discharge due to contact between the drive layer and the drive electrode. An insulating film such as silicon oxide can be formed in the layer.

As described above, a mirror yoke 18 for mounting the micromirror 19 is formed at the center of the drive layer (the intersection of the lattice structures 17 in FIG. 1). The mirror yoke is made of a material such as polysilicon, and the micromirror 19 mounted on the mirror yoke may have any shape, but is usually formed in the form of a circle or a rectangle. The size of the mirror is appropriately adjusted according to the width and resolution of the incident beam incident on the switch element, and the reflective surface of the mirror may be formed by depositing a metal such as gold or nickel.

FIG. 2 is a perspective view illustrating an optical wavelength switch structure in which the components shown in the exploded view of FIG. 1 are combined. In FIG. 2, the lines X and Y represent rotation axes orthogonal to each side of the drive layer 25, and the lines I and II represent rotation axes in the diagonal direction of the drive layer 25. As shown in FIG. 2, four upper driving electrodes 21 to 24 are formed to cover each side of the driving layer 25, and although not shown below the upper driving electrode, the upper driving electrodes 21 to 24 correspond to each upper driving electrode. Lower drive electrodes 21 'to 24' of the same shape are formed. In the non-driving state of the switch, the driving layer 25 and the micromirror 27 are supported to be parallel to the substrate by being spaced apart from the substrate 20 by four legs 26, and the four sides of the driving layer are respectively It is inserted in a non-contact state between the electrode plate of the upper drive electrode and the lower drive electrode. In order to obtain the electric force for rotating the drive layer, it is preferable that a sufficient area of each side of the drive layer in which the lattice structure is not patterned is inserted between the upper and lower drive electrodes. In a state in which a driving electrode is not applied to the switch, the driving layer is preferably positioned in parallel with these electrodes at an intermediate point between the upper driving electrode and the lower driving electrode. In addition, the distance between the drive layer and the upper and lower drive electrodes should be such that the drive layer can tolerate the required rotation angle to switch the incident light to the desired path. Hereinafter, a process in which the switch is operated by applying a voltage to the driving layer and the driving electrode of the optical wavelength switch of FIG. 2 will be described with reference to the accompanying drawings.

3 is a cross-sectional view of the optical wavelength switch cut along the rotation axis Y of FIG. As shown in FIG. 3, in the non-driven state of the switch, the driving layer 25 is connected to the pair of lower driving electrodes 21 ′ by the two ends 25A and 25B of the driving layer, respectively, by legs 26 indicated by dotted lines. 23 ') and the pair of upper drive electrodes 21, 23 are inserted in a non-contact state and arranged in parallel with these electrodes. When the switch is driven, the driving layer is biased to a constant voltage V _D from the external power supply through the leg 26. For example, the upper driving electrode 21 on the left side of FIG. 3 is biased to the potential V _H having the same polarity as V _D. At the same time, the lower driving electrode 21 ′ is biased to V _L having a potential different from that of V _D or having a potential of 0 V. At this time, preferably, V _H may have the same polarity and potential as V _D, and V _L may have a potential of 0 V. In this case, since the driving layer and the vertical driving electrode are driven with only two voltages, V _D and 0 V, the power supply structure and voltage pattern for driving the switch can be simplified. In this state, since the upper driving electrode and the driving layer are biased with the same polarity potential, the left end 25A of the driving layer is subjected to the electric repulsion directed downward in FIG. 3 by the upper driving electrode 21. In addition, since the driving layer and the lower driving electrode 25 have potentials having different polarities from each other, or the lower driving electrode has a potential of 0 V, the left end 25A of the driving layer is formed by the lower driving electrode 21 'due to the electrostatic induction. By the electric attraction in the downward direction of FIG. Accordingly, the left end 25A of the driving layer is forced downward by the repulsive force of the upper driving electrode and the attractive force of the lower driving electrode, so that the leg 26 is in contact with the substrate 20. Keep it. At the same time, when a driving voltage opposite to the driving voltage on the left side, that is, V _L and V _H is applied to the upper driving electrode 23 and the lower driving electrode 23 ′ on the right side of FIG. 3, the upper driving electrode 23 and the driving unit are driven. An electrical attraction force is applied between the right end 25B of the layer, and electrical repulsive force is applied between the lower drive electrode 23 ′ and the right end 25B of the drive layer so that the right end 25B of the drive layer is shown in FIG. 3. It will be lifted upwards. In this case, the left end of the drive layer is pressed against the substrate while the right end is lifted up, so the drive layer 25 is eventually rotated counterclockwise about the axis X of FIG.

On the other hand, when the driving voltages opposite to those described above are applied to the upper and lower driving electrode pairs 21, 21 ′ and 23, 23 ′ located on the left and right sides of FIG. 3, the left end 25A of the driving layer is the upper driving electrode 21. Direction and the right end 25B is pulled toward the substrate to rotate clockwise about axis X of FIG. 2. Thus, the driving voltage applied to the driving in of applying a constant bias voltage V _D to the layer state 2, and left upper and lower pair of electrodes of FIG. 3 (21, 21 ') and the right upper and lower pair of electrodes (23, 23'), V _H and By selecting the pattern of V _L , the driving layer can be rotated in both directions about the axis X of FIG. 2.

In addition, the cross section of the optical wavelength switch cut along the axis X of FIG. 2 becomes the same structure as FIG. Accordingly, as described above, the driving voltages V _H and V _L are applied to the upper and lower electrode pairs 22, 22 ′ and 24 and 24 ′ on the axis X of FIG. 2 while a constant bias voltage V _D is applied to the driving layer. When applied in the same manner as described, it can be easily seen that the driving layer can be rotated clockwise and counterclockwise about the axis Y of FIG. 2. In this way, by appropriately selecting the pattern of drive voltages applied to the four pairs of drive layers, the drive layer of the optical wavelength switch of the present invention can be rotated in any direction about the axes X and Y in FIG.

Hereinafter, an operation of rotating the driving layer 25 of FIG. 2 about the diagonal axes I and II will be described. Even when the drive layer is rotated about the diagonal axis, the drive layer is biased with a constant voltage V _D. At this time, the driving voltage V _H for applying the repulsive force to the driving layer is applied to the upper driving electrodes disposed on one side of the axis I, for example, the driving electrodes 21 and 24, and the lower driving electrodes 21 ′ and 24 corresponding thereto are applied. When applying a drive voltage V _L that applies a driving force to the layers') running layer is subjected to force directed toward the substrate. At the same time, when opposite driving voltages are applied to the upper and lower driving electrodes 22, 22 'and 23 and 23' opposite to the axis I, the driving layers opposite to the axis I are directed to the upper driving electrodes 22 and 23, respectively. The drive layer is then rotated counterclockwise about axis I of FIG. 2. In addition, when the driving voltage applied to the vertical driving electrodes on both sides of the axis I is reversed, the driving layer rotates clockwise about the axis I of FIG. 2. In the same manner, it can be easily seen that by appropriately selecting the pattern of the driving voltage applied to the upper and lower driving electrode pairs on both sides of the axis II, the driving layer can be rotated in both directions about the axis II of FIG. 2. As described above, the optical wavelength switch of the present invention applies a drive electrode of the same pattern to one adjacent pair of vertical drive electrodes on the diagonal rotation axis I or II, and simultaneously applies a reversed driving voltage to the adjacent pair of vertical drive electrodes. It can be seen that it can be rotated in both directions about any diagonal rotation axis.

As described above, the optical wavelength switch according to the exemplary embodiment illustrated in FIGS. 1 and 2 selects a pattern of driving voltages applied to four pairs of vertical driving electrodes disposed on each side of the driving layer, thereby selecting the driving voltage and the driving layer. The mounted micromirror can be rotated in any direction about four axes of rotation. Accordingly, the optical wavelength switch of the present invention can form various optical communication paths by reflecting the incident optical signal in various paths using one switch element. Since the optical wavelength switch element according to the present invention can arbitrarily form various optical communication paths by selecting only a voltage pattern applied to driving electrodes using a microprocessor or the like, it can be effectively used in an optical communication system requiring a large switching capacity.

In addition, the optical wavelength switch according to the present invention rotates the driving layer by the combined force of the electric attraction force and the repulsive force acting by the upper and lower driving electrodes and is mutually reversed to two pairs of driving electrode pairs facing each other with the driving layer interposed therebetween. Since the rotational force of the driving layer is doubled by applying the driving voltage of the pattern, the driving layer can be rapidly rotated even if the difference between the bias voltages of the driving layer and the upper and lower driving electrodes, that is, V _H -V _D and V _D -V _L is relatively small. It has the advantage of excellent response characteristics. In addition, in the optical wavelength switch according to the present invention, since the potential difference between the driving layer and the vertical driving electrode is relatively small, an arc discharge occurs between the driving layer and the driving electrode, thereby preventing the problem of shortening the life of the device.

Figures 4-5 show a modified structure of the embodiment of Figures 1-3, in which Figure 4-5 uses the same reference numerals for the components corresponding to those of Figures 2-3. 4 is a cross-sectional view corresponding to FIG. 3, in which the drive layer 25 with the micromirror 27 is mounted on an elastic beam 28 extending from the lower center of the drive layer instead of the legs 26 of FIGS. 2-3. By means of being supported on the substrate 20. The elastic beam 28 also serves as a conductive line for applying a bias voltage V _D to the driving layer 25 when the optical wavelength switch is driven. When a driving voltage having an appropriate pattern is applied to the upper driving electrodes 21 and 23 and the lower driving electrodes 21 'and 23' while the driving layer is supported by the elastic beam, the driving layer 25 is applied in the same principle as described above. ) Can be rotated in any direction about the axis X of FIG. 2, and if a suitable driving voltage is applied to other electrodes, the driving layer can be rotated as described with reference to FIGS. 2-3. , I and II can be rotated in any direction to obtain the effects of the above-described embodiment.

FIG. 5 illustrates an embodiment in which the elastic beam 28 of FIG. 4 is replaced with a pivot support 29. The pivot support 29 is usually installed at the center lower end of the drive layer 25 as in the elastic beam of FIG. 4. The pivot support 29 is such that both ends 25A, 25B of the drive layer 25 are not in contact with the top and bottom drive electrodes between the upper drive electrodes 21, 23 and the corresponding lower drive electrodes 21 ', 23'. It is desirable to be designed to have a range of pivotal motions that allow it to rotate at an angle necessary to switch incident light to a desired path within a range of not.

6 is a cross-sectional view illustrating the structure of the pivot support 29 of FIG. 4. In FIG. 6, the guide member 62 is formed in a box shape or a cylindrical shape on the substrate 60. A pin joint 61 is inserted into the guide member 62, a joint neck 63 extends from the pin joint through the guide hole of the guide member, and a support plate 64 is connected to the joint connecting member. The support plate 64 is equipped with a drive layer 65 of the light wavelength switch. In some cases, the driving layer 65 of the wavelength switch may be mounted using a separate member such as a connecting beam instead of being directly mounted to the support plate 64. The pivot structure of FIG. 6 is preferably formed by stacking a polysilicon layer with a sacrificial layer remodeled and removing the sacrificial layer using etching or the like. An example of such a process is described in US Pat. No. 6,040,935 and the like.

When the driving layer of the optical wavelength switch rotates by the driving voltage applied to the driving electrode, the pin joint and the supporting plate of the pivot support of FIG. 6 rotate by the rotation angle of the driving layer. When the pivot support is rotated by a predetermined angle, the lower end of the support plate comes into contact with the guide member to stop the rotation. That is, when the driving layer is supported by the elastic beam as shown in FIG. 4, the driving layer continuously rotates at an angle where the rotational force applied by the driving electrode and the elastic force of the elastic beam are in equilibrium, whereas the driving layer is driven by the pivot support part. In the case of supporting the driving layer is rotated by a certain angle limited by the pivot structure. Therefore, the pivot structure has the advantage of allowing the drive layer to have two stable positions when the switch is driven, and the advantage of being able to rotate the drive layer more quickly because it does not exert an elastic force that prevents rotation when the drive layer is rotated. Also have. As such, the support scheme of the drive layer may be selected according to the design requirements of the optical wavelength switch.

7 is a perspective view illustrating another embodiment of the optical wavelength switch of FIGS. 1 and 2. The configuration of the optical wavelength switch of FIG. 7 is substantially the same as that of the switches of FIGS. 6 and 7, but differs in that two pairs of upper and lower driving electrodes are provided on one side of the driving layer 79. . The switch of FIG. 7 applies a driving voltage to the electrode pairs 71 to 78 consisting of an upper driving electrode and a lower driving electrode to move the driving layer 79 in any direction about the rotational axes X, Y and the diagonal rotational axes I, II. Can be rotated. To rotate the drive layer clockwise around the axis of rotation X, a voltage is applied to the electrode pairs 71 and 78 to raise the drive layer, while the drive layer is lowered to the opposite electrode pairs 74 and 75. Apply a voltage so that the force to act. Then, the driving layer rotates clockwise about the rotation axis X by the upward force applied by the electrode pairs 71 and 78 and the downward force applied by the opposite electrode pairs 74 and 75. When the driving voltage applied to the upper and lower electrodes of the electrode pairs 71, 74, 75, and 78 is reversed, the driving layer rotates counterclockwise about the rotation axis X.

In order to rotate the drive layer about the diagonal axis I, for example, a driving voltage for raising the drive layer is applied to two electrode pairs 77 and 78 away from the axis I and the opposite electrode pairs 73 and 74. When a voltage for lowering the driving layer is applied, the driving layer is rotated clockwise about the rotation axis I. Even in this case, if the driving voltage applied to the vertical driving electrodes of the electrode pairs 73, 74, 77, and 78 is reversed, the driving layer rotates in the opposite direction about the rotation axis I. By controlling the pattern of the driving voltage applied to the electrode pairs 71 to 78 in this manner, the driving layer of the optical wavelength switch can be rotated in any direction around the rotational axis X, Y and the diagonal rotational axes I, II.

In addition, a driving voltage may be applied to all eight electrode pairs when the optical wavelength switch is driven. For example, when the driving layer is to be rotated clockwise about the rotation axis X of FIG. 7 as described above, a voltage pattern for raising the driving layer is applied to the electrode pairs 71 and 78, and the opposite electrode pair ( 74 and 75 are applied with a voltage for lowering the driving layer, while the electrode pairs 72 and 77 adjacent to the electrode pairs 71 and 78 have the same polarity as the voltage applied to the upper and lower drive electrodes of the electrode pairs 71 and 78. And applying a driving voltage having a relatively low potential to exert a lift force on the driving layer, and the electrode pairs 73 and 76 adjacent to the opposite side electrode pairs 74 and 75 are disposed on the upper and lower sides of the electrode pairs 74 and 75. A lowering force may be applied to the driving layer by applying a driving voltage having the same polarity as the voltage applied to the driving electrode and preferably having a relatively low potential. Using the method of applying the driving voltage to all eight electrode pairs as described above can improve the response characteristics of the switch element compared to the case of applying the driving voltage only to the four driving electrode pairs, and finely control the deflection angle of the micromirror. There is an advantage to this. In the above, an example in which the optical wavelength switch device of FIG. 7 is rotated in a clockwise direction about the rotation axis X has been described. However, even when the driving layer is rotated in an arbitrary direction about an arbitrary rotation axis among the rotation axes Y, I, and II, In the same manner as described above, a driving voltage may be applied to all of the eight pairs of driving electrodes to rotate the driving layer.

In FIG. 7, the driving layer 79 is supported by the legs 80 as in the case of FIGS. 1 and 2, but the driving layer 79 of the optical wavelength switch of FIG. 7 is, for example, as described with reference to FIG. 4. Likewise, it may be supported by an elastic beam coupled to the substrate at the center lower portion of the driving layer (or lattice structure) or by a pivot support as shown in FIGS. 5 and 6. The support scheme of the drive layer can be selected according to the design requirements of the optical wavelength switch. In addition, although two driving electrode pairs are disposed on one side of the driving layer in the embodiment of FIG. 7, three or more driving electrode pairs may be arranged on one side of the driving layer as necessary.

In the above description, an embodiment in which the driving layer is formed in a quadrangle and one or more upper and lower driving electrodes are disposed on each side of the driving layer to rotate the driving layer about four rotation axes, but the principle of the present invention will be described below. The same may be applied to the embodiment in which the driving layer is formed in a circular shape. FIG. 8A is a plan view of the optical wavelength switch device of the present invention having a circular drive layer, and FIG. 8B is a cross-sectional view of the optical wavelength switch of FIG. 8A taken along line I of FIG. 8A. As shown in FIGS. 8A and 8B, a circular drive layer 82 in which the micromirror 81 is mounted by the elastic beam 84 is supported on the substrate 85 and eight along the circumference of the drive layer. The upper drive electrodes 83A-83H and the lower drive electrodes 83'A-83'H corresponding thereto are provided. 8A and 8B, other structures except for the shape of the driving layer 82 may be configured similarly to those described above. For example, the center portion of the circular driving layer may be patterned in a lattice structure as in the embodiment of FIG. 1 or 7. In addition, the switch structure of the present embodiment may be made of a similar material in a similar manner to the embodiment described above.

The same method as described above for each of the upper and lower driving electrodes 83A, 83'A, 83E, 83'E while applying a constant bias voltage V _D to the driving layer 82 of FIG. 8B through the elastic beam 84. By applying a driving voltage having an appropriate pattern, the driving layer 82 may be rotated in a desired direction about the axis I of FIG. 8A. In addition, when the driving electrode pair to which the driving voltage is applied and the driving voltage applied to the driving voltage are appropriately selected, the driving layer 82 may be moved about any of the rotation axes I-IV in the same manner as described with reference to FIG. 7. It can rotate in the direction. Further, in the present embodiment, for example, when a driving voltage for generating an electric force for rotating the driving layer in one direction is applied to the driving electrode pairs 83A, 83'A and 83E, 83'E of Fig. 8B, respectively, The driving voltage pairs 83H, 83'H; 83B, 83'B; 83D, 83D '; 83F, 83'F adjacent to each other also have a driving voltage for rotating the driving layer in the same direction as described with reference to FIG. Can be applied. .

8A and 8B, when the driving layer is formed in a circular shape, eight or more, for example, 12 or 16 driving electrode pairs are arranged along the circumference of the driving layer, and the six or eight rotation axes are centered. Can be rotated. When the driving layer is formed in a quadrangle, it may be difficult to rotate the driving layer about four or more rotational axes. However, when the driving layer is formed in a circular shape as in the present embodiment, a pair of driving electrodes arranged around the driving layer may be formed. By increasing or decreasing the number, the number of axes on which the drive layer is rotated can be freely selected. In addition, the driving layer 82 may be supported on the substrate 85 by the elastic beam 84 as shown in FIG. 8B, but may be supported using a pivot support as shown in FIGS. 5 and 6. Even when the driving layer is supported by the pivot support, a driving voltage may be selectively applied to a plurality of pairs of driving electrodes arranged around the driving layer to freely select a rotation axis and a rotation direction in which the driving layer is rotated. As such, the principles of the present invention can be widely applied regardless of the shape of the drive layer constituting the switch or the number or arrangement of drive electrodes.

The optical wavelength switch element of the present invention arranges four or more driving electrode pairs around the driving layer and applies various patterns of driving voltages to each driving electrode to move the driving layer and the micromirror in any direction about four or more rotation axes. The number of optical communication paths can be set as compared with the conventional optical wavelength switch which can rotate and rotate about one axis. Therefore, the switching system including the switch element of the present invention can have a greatly increased switching capacity compared to the switching system using the conventional switch element even if using the same number of switch elements. In addition, the optical wavelength switch element of the present invention is driven by rotating the drive layer equipped with the micromirror by using the combined force of the electric attraction force and the repulsive force acting by a pair of drive electrodes composed of an upper drive electrode and a lower drive electrode. Even when the difference between the voltages applied to the layer and the vertical drive electrode is lower than that of the conventional optical wavelength switch element, the optical wavelength switch can be effectively driven, a good response characteristic can be obtained, and the potential difference between the driving layer and the vertical drive electrode can be improved. It can be reduced to prevent the discharge phenomenon between the drive layer and the drive electrode.

As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this, Various modifications and modifications based on the technical idea of this invention may belong to the scope of the present invention.

Claims (22)

In the optical wavelength switch device used in an optical communication network, Switch substrates; A drive layer including a mirror supported on the substrate to be rotatable in an arbitrary direction and reflecting incident light; Four or more pairs of drive electrodes each including a lower drive electrode and an upper drive electrode and disposed around the drive layer; The driving layer is biased to a predetermined potential, and a driving voltage of the same polarity as that applied to the driving layer is applied to one of the upper driving electrode and the lower driving electrode of the at least one pair of driving electrodes, and the other And a driving voltage having a polarity or 0 V potential opposite to that applied to the driving layer. The method according to claim 1, And the driving layer has a generally rectangular shape and the driving electrode pairs are disposed at least one side of one side of the driving layer. The method according to claim 1, And the driving layer has a generally circular shape and the driving electrode pairs are arranged along the circumference of the driving layer. The method according to claim 1, The driving voltages respectively applied to the upper driving electrodes and the lower driving electrodes of the driving electrode pair to which the driving voltage is applied are reversed, and the upper driving electrodes of the driving electrode pairs facing each other with the driving layer interposed therebetween; An optical wavelength switch device applied simultaneously to each of the lower driving electrodes. The method according to claim 1, A driving voltage having the same polarity and the same potential as the bias voltage applied to the driving layer is applied to one of the lower driving electrode and the upper driving electrode of the driving electrode pair to which the driving voltage is applied, and to the other electrode. An optical wavelength switch device to which a driving voltage of 0 V is applied. The method according to any one of claims 1 to 5, And the driving layer can be rotated in any direction about any one of four or more rotation axes according to a pattern of driving voltages applied to the driving electrode pairs. The method according to any one of claims 1 to 5, And an electrode plate on which the lower driving electrode is formed, the upper driving electrode extends from the substrate, and an upper portion of the lower driving electrode covers a portion of the driving layer. The method according to claim 7, And at least a portion of the drive layer is inserted in a non-contact state between the lower drive electrode and the electrode plate of the upper drive electrode. The method according to any one of claims 1 to 5, And the driving layer is supported on the substrate such that the driving layer is positioned between the lower driving electrode and the upper driving electrode in an insulated state from the substrate by a plurality of legs formed in the driving layer. The method according to any one of claims 1 to 5, And the driving layer is supported on the substrate such that the driving layer is positioned between the lower driving electrode and the upper driving electrode in an insulated state from the substrate by one elastic beam or pivot structure. The method according to any one of claims 1 to 5, And a lattice structure, a horizontal member, or a vertical member formed at a central portion of the driving layer. The method according to any one of claims 1 to 5, And the substrate, the driving layer and the vertical driving electrode are formed of a semiconductor material such as silicon or polysilicon. The method according to any one of claims 1 to 5, And a mirror mounted on the yoke formed at the center of the drive layer. The method according to any one of claims 1 to 5, And an insulating layer formed on a surface of the driving layer or the vertical driving electrode. A drive layer comprising a switch substrate, a drive layer including a mirror supported to deflect by the substrate and reflecting incident light, and four or more drive electrode pairs formed of an upper drive electrode and a lower drive electrode and disposed around the drive layer. In the method for driving an optical wavelength switch device for optical communication, Biasing the driving layer to a predetermined potential and applying a driving voltage having the same polarity as the voltage applied to the driving layer to one of the upper driving electrode and the lower driving electrode of at least one pair of driving electrodes; And applying a driving voltage having a polarity or 0 V potential opposite to that applied to the driving layer. The method according to claim 15, The upper driving electrode and the upper driving electrode applied to the lower driving electrode, respectively, to which the driving voltage is applied; An optical wavelength switch driving method applied simultaneously to each of the lower driving electrodes. The method according to claim 15, A driving voltage having the same polarity and the same potential as the bias voltage applied to the driving layer is applied to one of the lower driving electrode and the upper driving electrode of the driving electrode pair to which the driving voltage is applied, and 0 V to the other electrode. An optical wavelength switch driving method for applying a driving voltage of. The method according to claim 15, The drive layer has a generally rectangular shape and is disposed on one side of the rotation axis about a rotation axis orthogonal to each side of the drive layer through the center of the drive layer or a rotation axis in a diagonal direction of the drive layer. A driving voltage in a form of generating a force is applied to the driving electrode pair in a direction of raising or lowering the driving layer with respect to the substrate, and a force opposite to the direction is applied to the driving electrode pair disposed on the other side of the rotating shaft. An optical wavelength switch driving method for applying a driving voltage of a type to be generated. The method according to claim 15, And the driving layer has a circular shape, and the pair of driving electrodes is disposed along the circumference of the driving layer. The method according to any one of claims 15 to 19, And the driving layer can be rotated in any direction about any one of four or more rotation axes according to a pattern of driving voltages applied to the pair of driving electrodes. The method of claim 20, A driving voltage is applied to all of the pair of driving electrodes located on one side of the rotation axis to generate an electric force that raises or lowers the driving layer with respect to the substrate, and to all of the pair of driving electrodes located on the other side in the opposite direction. The optical wavelength switch driving method is applied a driving voltage for generating a. The method according to any one of claims 15 to 19, And the driving layer is supported on the substrate in an insulated state from the substrate by an elastic beam or a pivot structure.