JP2010217779A - Optical switch and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical switch that effectively suppresses crosstalk and Rabbit Ear equally to use of a tertiary or higher function which may result in high cost without using the high-order function, and to provide a method of controlling the optical switch. <P>SOLUTION: A calculation unit 17 calculates axis voltages Vx and Vy for rotating a mirror 1041 on an (x) axis and a (y) axis, respectively, by a prescribed amount from a control variable Vt. An electrode control unit 18 calculates driving voltages to be applied to electrodes from the Vx and Vy, respectively, and applies the voltages to corresponding electrodes. A comparator 13 determines a deviation to a target value of detection results. An adder 15 adds a compensation amount corresponding to the deviation to the control variable Vt and negatively feeds the deviation back to the control variable Vt. Consequently, the operation of the mirror having the two axes can be controlled with one control variable Vt without using any high-order function, so that the operation of the mirror that achieves reduction in crosstalk and suppression of Rabbit Ear can be achieved at low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical switch used in a communication optical transmission device, a wavelength routing device, and the like, and an optical switch control method.

  In recent years, in the field of optical communication, high-speed communication utilizing the characteristics of light has been realized by transmitting an optical signal to a partner without converting it into an electrical signal. Also, it has been realized to perform large-capacity optical transmission using one optical fiber by WDM (Wavelength Division Multiplexing) technology that multiplexes one optical signal corresponding to one wavelength. With the development of such optical communication technology, an optical switch that switches a path without converting an optical signal into an electric signal or the like has attracted attention.

  The optical switch has been promoted to have higher functionality as the optical communication network becomes larger. Conventionally, a simple 1 × 2 switch having one input port and two output ports has been used. However, in recent years, it has hundreds of input ports and output ports and can perform optical path control in units of ten thousand units. A matrix switch that can be used, a wavelength selection switch that selects an arbitrary wavelength from several tens of wavelengths, and outputs the selected wavelength from any of a plurality of output fibers have been proposed. A spatial optical system optical switch can realize these switches with high functionality and small size.

  Spatial optical system optical switches achieve high functionality and miniaturization by three-dimensionally arranging spatial optical components such as lenses and mirrors along with optical fibers. For such a spatial optical switch, a micromirror device (see, for example, Patent Document 1) created by MEMS (Micro Electro Mechanical Systems) technology is often used. The MEMS micromirror device is a device that applies a voltage to an electrode disposed opposite to a mirror and rotates the mirror around a rotation axis by an electrostatic force generated between the electrode and the mirror. Since the MEMS micromirror device can rotate the mirror by a plurality of rotating shafts, for example, in addition to the first rotating shaft that realizes switching of the optical path, the MEMS micromirror device has a first orthogonal to the first rotating shaft. The optical loss can be controlled by tilting the mirror about the rotation axis 2 and the power of the optical signal passing through the mirror can be controlled to an arbitrary value. The optical power control is used, for example, in a WDM optical network to suppress power variation between optical signals caused by a wavelength gain / loss difference in an optical transmission line. Since this function is related to the number of nodes that can be connected, it is an indispensable function for future wavelength selective switches for wavelength division multiplexing optical networks.

  Such a wavelength selective switch is required to have high optical performance as the optical network becomes larger. For example, when an optical signal passes through multiple nodes, an optical amplifier is provided to compensate for the optical loss. However, the wavelength selective switch has a transmission spectrum that can amplify only the necessary signal component. The spectrum is required to pass only the necessary band. In addition, since the number of ports also increases, the optical signal level that leaks to the adjacent ports, generally called port crosstalk (PXT), must be sufficiently suppressed below the required value.

  An example of such a wavelength selective switch is shown in FIGS. Here, the wavelength selective switch 100 shown in FIG. 7 adds a plurality (maximum m-waves) of channel (wavelength) signals input from a plurality of input ports and outputs the combined signal from one output port. Switch. On the other hand, the wavelength selective switch 200 shown in FIG. 8 is a drop-type wavelength selective switch that outputs a plurality of channel signals (maximum m waves) input from one input port from one of the plurality of output ports. is there. 7 and 8, equivalent components are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

  A wavelength selective switch 100 shown in FIG. 7 includes n input-side optical fibers 101-1 to 101-n that function as input ports, one output-side optical fiber 102 that functions as an output port, and an input-side optical fiber. A diffraction grating 103 that diffracts input light from 101-1 to 101-n and demultiplexes it into a maximum of m optical signals having different wavelengths, and reflects an optical signal diffracted by the diffraction grating 103 for each wavelength. MEMS mirror devices 104-1 to 104-m that output from the output-side optical fiber 102; a demultiplexer 105 that demultiplexes the optical signal branched from the output-side optical fiber 102 for each of m specific wavelengths; Photodiodes 106-1 to 106-m for monitoring each light demultiplexed by the demultiplexer 105, and detection results of the photodiodes 106-1 to 106-m are A / D converted. / D converter 107, and a mirror control circuit 108 for controlling the driving of the MEMS mirror device 104-1 to 104-m based on the output from the A / D converter 107. Here, each mirror of the MEMS mirror devices 104-1 to 104-m is rotatable about the x axis in the direction in which the mirrors are arranged and the y axis orthogonal to the x axis. The optical fibers 101-1 to 101-n are arranged in the direction along the y-axis.

  The wavelength selective switch 200 shown in FIG. 8 diffracts input light from one input-side optical fiber 101, n output-side optical fibers 102-1 to 102-n, and input-side optical fiber 101, and wavelength. Diffracting grating 103 which demultiplexes into a maximum of m optical signals having different wavelengths, and the optical signal diffracted by this diffraction grating 103 is reflected for each wavelength and output from the corresponding output side optical fibers 102-1 to 102-n. MEMS mirror devices 104-1 to 104-m to be combined, a combiner 109 for combining the outputs from the output-side optical fibers 102-1 to 102-n, and m specific light beams combined by the combiner 109 A demultiplexer 105 that demultiplexes each wavelength, a photodiode 106-1 to 106-m that monitors each light demultiplexed by the demultiplexer 105, and the photodiode 106-1 to 106-m. An A / D converter 107 that A / D converts the detection result, and a mirror control circuit 108 that controls the driving of the MEMS mirror devices 104-1 to 104-m based on the output from the A / D converter 107. I have. Here, each mirror of the MEMS mirror devices 104-1 to 104-m is rotatable about the x axis in the direction in which the mirrors are arranged and the y axis perpendicular to the x axis, and the output side The optical fibers 102-1 to 102-n are arranged on the locus of the light beam when the mirror is rotated around the x axis.

  Here, the difference between the wavelength selective switch 100 shown in FIG. 7 and the wavelength selective switch 200 shown in FIG. 8 is the difference in the input / output direction whether it is an N-input 1-output Add type or a 1-input N-output Drop type. The difference and the configuration for monitoring the signal light power on the output side accompanying this, that is, in the wavelength selective switch 100 shown in FIG. 7, a part of the optical power from the output side optical fiber 102 is simply branched and the channel (wavelength 8), the wavelength selective switch 200 shown in FIG. 8 branches the optical signal from each of the plurality of output side optical fibers 102-1 to 102-n. Then, after the signals are combined into one by the combiner 109, the signal is input to the demultiplexer 105 for separating the signals for each channel. Other configurations and operating principles are the same for both.

  For convenience, FIG. 9 shows a simplified version of the wavelength selective switch 100 shown in FIG. 7 with a focus on one channel.

  The wavelength selective switch 100 shown in FIG. 9 includes inputs from n input side optical fibers 101-1 to 101-n, one output side optical fiber 102, and input side optical fibers 101-1 to 101-n. A diffraction grating 103 that diffracts light, a MEMS mirror device 104 that reflects an optical signal diffracted by the diffraction grating 103 and outputs it from the output side optical fiber 102, and a part of the output from the output side optical fiber 102 is branched. A coupler 110 for converting the optical signal branched by the coupler 110 into an electrical signal, an A / D converter 107 for A / D converting the electrical signal from the photodiode 106, and the A / D And a mirror control circuit 108 for controlling the driving of the MEMS mirror device 104 based on the output from the D converter 107. Here, the input side optical fibers 101-1 to 101-n, the output side optical fiber 102, the diffraction grating 103, and the MEMS mirror device 104 constitute a spatial optical system switch unit 300. The photodiode 106, the A / D converter 107, and the mirror device circuit 108 constitute a drive control unit 400.

  Here, as shown in FIG. 10A, a specific structural example of the MEMS mirror device that rotates around two axes, the x-axis and the y-axis orthogonal to the x-axis, will be described. The mirror 1041 of the MEMS mirror device 104 is connected to any one of n input ports and one output port with respect to the x-axis, that is, in any rotation direction around the x-axis. It rotates so that there is a minimum loss between the input port and one output port. This rotates to move the direction of the optical signal in the direction in which the input ports are arranged. On the other hand, the mirror 1041 rotates about the y axis orthogonal to the x axis with respect to the y axis, and thus rotates to move the direction of the optical signal in a direction orthogonal to the direction in which the input ports are arranged. Therefore, in order to control the coupling rate from the input port to the output port, that is, the loss, it is possible to rotate either the x-axis or the y-axis, but the rotation around the x-axis governing the movement of the ports in the alignment direction is possible. The rotation is mainly used for the loss control, and the rotation around the y-axis, which controls the movement in the direction orthogonal to the port arrangement direction, is mainly used for the loss control.

  In such a wavelength selective switch 100, when performing negative feedback control, the control device 108 sets the deviation between the output power of the optical signal obtained by the photodiode 106 and the A / D converter 107 and the target value to zero. Thus, the mirror 1041 of the MEMS mirror device 104 is rotated.

  For example, as shown in FIGS. 10B to 10D, the MEMS mirror device 104 includes a mirror 1041 having a gimbal structure and electrodes 1042 a to 1042 d arranged to face the lower side of the mirror 1041. . The electrodes 1042a to 1042d are provided on the same plane substantially parallel to the main surface of the mirror 1041, the electrodes 1042a and 1042b are symmetric with respect to the x axis, and the electrodes 1042c and 1042d are symmetric with respect to the y axis. Often arranged. Since the potential of the mirror 1041 is the same as the ground potential, when a voltage is applied to the electrodes 1042a to 1042d, an electrostatic attractive force is generated between the electrodes 1042a to 1042d and the mirror 1041, and this electrostatic attractive force. And the mirror 1041 tilts to an angle that balances the restoring force of the torsion spring that supports the mirror 1041. Since there are two rotation directions of the mirror 1041 around the x axis and the y axis, if there are two voltages (that is, control variables) for controlling the rotation, the angle of the two axes can be arbitrarily controlled. In addition, it is easier to construct a control method by minimizing the number of variables than handling many variables. Therefore, four voltages (Va, Vb, Vc, Vd: hereinafter referred to as electrode voltages) applied to the four electrodes 1042a to 1042d are converted into two voltages Vx and Vy as shown in the following expressions (1) and (2). It shall be expressed as

Vx = Va−Vb (1)
Vy = Vc−Vd (2)

  By using the above equations (1) and (2), it is possible to treat the voltage that controls the rotation about the x-axis as Vx and the voltage that controls the rotation about the y-axis as Vy. Hereinafter, the voltages Vx and Vy are referred to as axial voltages. Normally, in the case of a biaxially driven mirror, in addition to the gimbal structure mirror as shown in FIGS. 10A to 10D, an axial voltage with a limited variable is used instead of the electrode voltage. In many cases, mirror drive control is performed. Further, the relationship between the electrode voltage and Vx, Vy is not necessarily limited to the relationship shown in the above formulas (1) and (2), and other relational expressions are adopted in consideration of the mirror characteristics and the like. There is also.

  In the MEMS mirror device 104, when the axial voltage Vx is changed, the mirror 1041 rotates about the x axis. As shown in FIG. 9, since the input ports are arranged in a direction perpendicular to the x-axis, there are as many rotation angles about the x-axis as connecting the input ports and output ports by the number n of the input ports. . Therefore, the number V of the input ports also exists as the voltage Vx that optimally couples each input port and output port.

  On the other hand, in the MEMS mirror device 104, when the axial voltage Vy is changed, the mirror 1041 rotates about the y axis. As shown in FIG. 9, since the input ports are arranged in a direction parallel to the y-axis, if an input port and an output port are optimally coupled (the state where the loss is minimized), the y-axis is rotated. If the rotation is given, the coupling state deteriorates and the loss between the input port and the output port increases. At this time, since the mirror is rotated in the direction orthogonal to the direction in which the input ports are arranged, the coupling state of the other ports is not affected. That is, the rotation around the y-axis only reduces the coupling efficiency with a certain port and has little influence on other ports. For this reason, the rotation around the y-axis is mainly used for loss control. The loss characteristic around the y-axis shows a mountain shape where the peak is at the point where the loss is the smallest, and the loss increases as it deviates from this peak. Therefore, there is only one voltage Vy that optimally couples a certain input port and output port.

  That is, as shown in FIG. 11, there are peaks for N ports according to the number of input ports in the direction of the Vx axis. On the other hand, there is only one peak for each port in the Vy axis direction. Therefore, the loss contour map on the Vx-Vy plane shows a characteristic shape in which N ellipses elongated in the Vy axis direction are arranged in the Vx direction. Depending on the employed mirror, the mirror may operate only in the positive direction of Vx or Vy. In such a case, the loss contour map is obtained by extracting only the operating range of the mirror from FIG.

  12A to 12C show the difference between the case where the variable for controlling the loss is taken as Vx and the case where it is taken as Vy.

  Basically, the loss control is performed using Vy, but can also be performed by rotating the mirror 1041 only in the x-axis direction using Vx as shown in FIG. 12C. However, in this case, if the loss of a certain port is to be reduced, a phenomenon called so-called crosstalk occurs in which light leaks to a port adjacent to that port. Since this crosstalk becomes noise with respect to the optical signal, it must be suppressed to a specified value or less. This specified value depends on the network design, but a low value such as less than −30 dB is required. In order to change the loss and keep the crosstalk small, as shown in FIG. 12B, it is optimal to control the loss by rotating the mirror 1041 around the y-axis orthogonal to the x-axis.

  However, when loss control is performed using only the y-axis, other optical characteristics may be degraded. Specifically, when the value of Vy is increased and the mirror 1041 is rotated at a large angle around the y axis, the diffracted light from the end face of the mirror 1041 remains in the transmission spectrum, and the end of the transmission band. Loss may remain without decreasing, and a spectrum shape in which the vicinity of both ends of the transmission band protrudes in a mountain shape may occur. This is called Rabbit Ear because it looks like it pops out like a rabbit ear. This phenomenon reduces the transmission band of the network in an optical network that passes through a plurality of wavelength selective switches and optical amplifiers because the “ear” portion is also repeatedly amplified and “grows”. Therefore, it is required to make Rabbit Ear small.

  From the viewpoint of reducing Rabbit Ear, as shown in FIG. 12C, it is desirable to control the loss using only rotation around the x axis where the direction of the diffracted light at both ends of the mirror does not fall within the transmission spectrum. However, in this case, the problem of crosstalk occurs as described above.

  Thus, crosstalk and Rabbit Ear were difficult to solve by making the axis for controlling the loss either the x-axis or the y-axis. Therefore, as shown in FIGS. 13A and 13B, the mirror 1041 is rotated around the x axis in the vicinity of the peak, and the mirror 1041 is rotated around the y axis when deviating from the peak, so that crosstalk and Rabbit Ear can be simultaneously performed. It has been proposed to solve. Since the Rabbit Ear has a large loss, that is, it becomes prominent at a position away from the peak, it makes sense to rotate the mirror 1402 around the x axis in the initial stage.

  However, when the axis to be rotated is switched, the target variable when switching the axis must be changed. For example, on the elliptical loss contour line as shown in FIG. Then, the loss characteristic changes greatly. For this reason, when negative feedback control is performed on the power, the control parameter must be reset every time the axis is switched in order to keep the feedback amount optimal, resulting in complicated control. End up.

  For this reason, when the loss is increased by changing Vx and Vy at the same time while having a predetermined relationship, instead of alternately switching the rotation around the x axis and the y axis as in the prior art. By rotating not only around the y-axis but also around the x-axis, the diffracted light from the end face of the mirror remaining in the transmission spectrum can be reduced and Rabbit Ear can be suppressed. In this way, since the loss characteristics change continuously, it is possible to realize light intensity control without resetting variables and control parameters.

  Here, the above-mentioned predetermined relationship is, for example, a case where Vx and Vy are expressed by a linear function of the newly introduced control variable Vt as in the following expressions (3) and (4). Show.

Vx = A · Vt + Vx ₀ (3)
Vy = B · Vt + Vy ₀ (4)

In the above formulas (3) and (4), (Vx ₀ , Vy ₀ ) is a coordinate indicating a peak on the Vx-Vy plane. When the control variable Vt is introduced, the shaft voltages having two variables can be further combined into one. As a result, when the light intensity is controlled by PID control or the like, the light intensity can be easily controlled using the control variable Vt.

  As described above, if the crosstalk can be reduced below the allowable value and the Rabbit Ear can be suppressed by rotating the mirror about the x axis and then rotating about the y axis, the above equations (3), ( Rather than expressing both expressions relating to Vx and Vy as a linear function as in 4), it is more appropriate to express the Vy side as a higher order function as in the following expressions (5) and (6).

Vx = A · Vt + Vx ₀ (5)
Vy = B · Vt ^α + Vy ₀ (6)

  In the above formula (6), α is an integer of 2 or more. FIG. 14A and FIG. 14B show the trajectory on the loss contour when a high-order function is introduced, and the loss characteristics with respect to the control variable. It can be seen that the Rabbit Ear suppression effect similar to the loss characteristics shown in FIGS. 13A and 13B can be obtained while the differential value of the loss characteristics is continuous. In this way, by using a higher-order function, it is possible to first rotate in the x-axis direction and increase the y-axis direction as the control voltage Vt increases.

JP 2003-057575 A

  However, when a high-order function is introduced to calculate the shaft voltage, the amount of change in loss with respect to the control variable Vt becomes extremely large due to nonlinearity in a region where the control variable Vt is large. This tendency becomes more prominent as the degree α of the higher order function is larger. If the loss change amount with respect to the control variable Vt is extremely different between the case where the control variable Vt is small and the case where the control variable Vt is large, it is necessary to reset the control parameter by dividing the case somewhere in the control variable Vt as in the conventional case. Since the loss characteristic is continuously changed with respect to the control variable Vt, the order must be limited. In addition, the calculation load is higher than in the case of the linear function, and the accuracy of the control variable Vt needs to be higher than the axis voltage Vy in order to ensure the calculation accuracy of the axis voltage Vy due to the nonlinearity of the high-order function. There is. For this reason, the control circuit is complicated and expensive because it requires a high-performance arithmetic unit with high arithmetic capability and high digit accuracy.

  Therefore, the present invention provides an optical switch and an optical switch control method capable of realizing effective crosstalk and suppression of Rabbit Ear equivalent to those without using a higher-order function of third order or higher that may cause high cost. The purpose is to provide.

In order to solve the above-described problems, an optical switch according to the present invention includes at least one light input unit that inputs input light, at least one light output unit that outputs output light, and a light input unit or light. A mirror device having an x-axis used for selecting an output unit and a mirror rotatably supported with respect to a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror; The optical switch includes a drive control unit that applies an electrode voltage to rotate the mirror about the x-axis and the y-axis, and a detection unit that detects the light intensity of the output light output from the light output unit. The drive control unit calculates a control variable Vt for calculating the control variable Vt corresponding to the target light intensity, and shaft voltages Vx and Vy for rotating the mirror around the x axis and the y axis from the control variable Vt. Axial power to be calculated A calculation unit; an electrode voltage applied to each electrode from Vx and Vy; an electrode voltage control unit that applies the electrode voltage to the corresponding electrode; a detection result detected by the detection unit; and a target light intensity; And a compensation unit that adds a compensation amount according to the deviation output from the comparison unit to the control variable Vt and negatively feeds back the deviation to the control variable Vt. (Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd). Assuming the length of the trajectory through which Vt passes, the shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ , and the shaft voltage Vy is Vy = (Vyd / L ² ) · which is characterized by being represented by vt ² + Vy ₀ A.

Another optical switch according to the present invention is used for selecting at least one optical input unit that inputs input light, at least one optical output unit that outputs output light, and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to the x-axis and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror, and applying an electrode voltage to the electrodes A drive control unit that rotates the X-axis and the y-axis, a detection unit that detects the light intensity of the output light output from the light output unit, and the output light detected by the detection unit for each wavelength. An optical switch including a wave demultiplexing unit, wherein the drive control unit converts the output light demultiplexed by the demultiplexing unit into an electric signal, converts the electric signal into digital, and outputs the output light. An A / D converter that outputs a light intensity value of A comparison unit for obtaining a deviation between the light intensity value of the force light and the target value of the light intensity, a compensation amount calculation unit for obtaining a compensation amount proportional to the deviation output from the comparison unit, and the compensation amount as a control variable Vt An adder that adds negative feedback, a delay unit that holds the control variable Vt with the compensation amount added for an arbitrary control period, and a mirror from the control variable Vt with the compensation amount added to the x-axis and y An axial voltage calculation unit that calculates axial voltages Vx and Vy that rotate around the axis, and an electrode voltage control unit that calculates an electrode voltage to be applied to each electrode from Vx and Vy and applies this electrode voltage to the corresponding electrode The electrodes include electrodes a and b for controlling the rotation of the mirror about the x axis, and electrodes c and d for controlling the rotation of the mirror about the y axis, and (Vx ₀ , Vy ₀ ). Coordinates on the Vx-Vy plane where the optical loss is minimized (Vxd, Vyd) arbitrary coordinates on Vx-Vy plane, L from _{(Vx 0, Vy 0) (} Vxd, Vyd) the length of the trajectory through which Vt up, the electrode voltage applied to the electrode a Assuming Va, the electrode voltage applied to the electrode b is Vb, the electrode voltage applied to the electrode c is Vc, and the electrode voltage applied to the electrode d is Vd, the axial voltage Vx is Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb, and the shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd. It is a feature.

In the optical switch, on the Vx-Vy plane, a maximum range of optical loss in the optical output unit corresponding to (Vx ₀ , Vy ₀ ) and a range in which crosstalk from the optical output unit adjacent to the optical output unit occurs. (Vxc, Vyd), and when arbitrary constants ξ and η are expressed by ξ = 2−η−2 (1-η) ^1/2 , (Vxd, Vyd) is (Vxd, Vyd) ) = (Vxc / η, Vyc / ξ).

Another optical switch according to the present invention is used for selecting at least one optical input unit that inputs input light, at least one optical output unit that outputs output light, and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to the x-axis and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror, and applying an electrode voltage to the electrodes And a drive control unit that respectively rotates the X axis and the y axis, and the drive control unit calculates a control variable Vt corresponding to a target optical loss; , An axial voltage calculation unit for calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis, respectively, from the control variable Vt, and an electrode voltage applied to each of the electrodes from Vx and Vy, and this electrode voltage And a corresponding electrode voltage control unit applied to the electrodes, (Vx _0, Vy ₀₎ coordinates on Vx-Vy plane light loss becomes minimum of, (Vxd, Vyd) any on of Vx-Vy plane If the coordinate, L is the length of the trajectory through which Vt from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd) passes, the axial voltage Vx is Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx represented by _0, the axial voltage Vy are those characterized by being represented by ^{Vy = (Vyd / L 2)} · Vt 2 + Vy 0.

Another optical switch according to the present invention is used for selecting at least one optical input unit that inputs input light, at least one optical output unit that outputs output light, and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to the x-axis and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror, and applying an electrode voltage to the electrodes And a drive control unit that respectively rotates the X axis and the y axis, and the drive control unit calculates a control variable Vt corresponding to a target optical loss; , An axial voltage calculation unit for calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis, respectively, from the control variable Vt, and an electrode voltage applied to each of the electrodes from Vx and Vy, and this electrode voltage An electrode voltage control unit that applies to a corresponding electrode, and the electrodes are electrodes a and b that control the rotation of the mirror about the x-axis, and electrodes c and d that control the rotation of the mirror about the y-axis. (Vx ₀ , Vy ₀ ) are coordinates on the Vx-Vy plane where the optical loss is minimum, (Vxd, Vyd) are arbitrary coordinates on the Vx-Vy plane, and L is (Vx ₀ , Vy ₀ ) To (Vxd, Vyd), the length of the trajectory Vt passes, the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, the electrode voltage applied to the electrode c is Vc, the electrode Assuming that the electrode voltage applied to d is Vd, the shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb, and the shaft voltage Vy is represented by ^{Vy = (Vyd / L 2)} · Vt 2 + Vy 0 and Vy = Vc-Vd And it is characterized in and.

  The optical switch further includes a storage unit that stores in advance the correspondence between the optical loss and the control variable Vt, and the control variable calculation unit acquires the control variable Vt corresponding to the target light intensity from the storage unit. Also good. The storage unit further stores in advance an approximate expression of the control variable Vt that approximates the correspondence between the optical loss and the control variable Vt, and the control variable calculator calculates the target based on the approximate expression stored in the storage unit. The control variable Vt corresponding to the light intensity to be calculated may be calculated.

The optical switch control method according to the present invention is used to select at least one optical input unit that inputs input light, at least one optical output unit that outputs output light, and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to an x-axis and a y-axis orthogonal to the x-axis, a plurality of electrodes arranged to face the mirror, and applying an electrode voltage to the electrodes A method for controlling an optical switch, comprising: a drive control unit that rotates a mirror about each of an x axis and a y axis; and a detection unit that detects the light intensity of output light output from the light output unit. A control variable calculation step for calculating a control variable Vt corresponding to the light intensity, and an axial voltage calculation step for calculating shaft voltages Vx and Vy for rotating the mirror about the x axis and the y axis, respectively, from the control variable Vt, The electrode voltage applied to each electrode is calculated from x and Vy, and the deviation between the electrode voltage control step for applying this electrode voltage to the corresponding electrode and the detection result detected by the detector and the target light intensity is obtained. A comparison step and a compensation step of adding a compensation amount according to the deviation output from the comparison unit to the control variable Vt and negatively feeding back the deviation to the control variable Vt, and (Vx ₀ , Vy ₀ ) The coordinates on the Vx-Vy plane where the optical loss is lowest, (Vxd, Vyd) are arbitrary coordinates on the Vx-Vy plane, and L passes through Vt from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd). Assuming the length of the locus, the shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ , and the shaft voltage Vy is Vy = (Vyd / L ² ) · Vt ² + Vy. It is characterized by being represented by ₀ It is intended.

According to another aspect of the invention, there is provided an optical switch control method comprising: selecting at least one optical input unit that inputs input light; at least one optical output unit that outputs output light; and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to an x-axis used in the above-mentioned and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged opposite to the mirror, and applying an electrode voltage to the electrodes A drive control unit that rotates the mirror about the x-axis and the y-axis, a detection unit that detects the light intensity of the output light output from the light output unit, and a wavelength of the output light detected by the detection unit A method of controlling an optical switch including a demultiplexing unit that demultiplexes each time, a photoelectric conversion step of converting output light demultiplexed by the demultiplexing unit into an electric signal, and digital conversion of the electric signal for output Outputs the value of light intensity A / A conversion step, a comparison step for obtaining a deviation between the light intensity value of the output light and the target value of the light intensity, a compensation amount calculating step for obtaining a compensation amount proportional to the deviation output by the comparison step, and a compensation amount An addition step for negative feedback to the control variable Vt, a delay step for holding the control variable Vt with the compensation amount added for an arbitrary control period, and a mirror from the control variable Vt with the compensation amount added An axial voltage calculation step for calculating axial voltages Vx and Vy that rotate about the x axis and the y axis, respectively, an electrode voltage to be applied to each electrode from Vx and Vy, and this electrode voltage to be applied to the corresponding electrode An electrode voltage control step, and the electrode includes electrodes a and b for controlling the rotation of the mirror about the x-axis and electrodes c and d for controlling the rotation of the mirror about the y-axis. (Vx _0, Vy ₀₎ coordinates on Vx-Vy plane light loss becomes minimum of, (Vxd, Vyd) arbitrary coordinates on Vx-Vy plane, L from the _{(Vx 0, Vy 0) (} Vxd , Vyd), the length of the trajectory through which Vt passes, the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, the electrode voltage applied to the electrode c is applied to Vc, and the electrode d is applied Assuming that the electrode voltage is Vd, the shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb, and the shaft voltage Vy is Vy = ( Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd.

In the above-described optical switch control method, the maximum range of optical loss in the optical output unit corresponding to (Vx ₀ , Vy ₀ ) on the Vx-Vy plane and crosstalk from the optical output unit adjacent to the optical output unit When the coordinates of the intersection with the resulting range are (Vxc, Vyc), and arbitrary constants ξ and η are expressed by ξ = 2−η−2 (1-η) ^1/2 , (Vxd, Vyd) is ( Vxd, Vyd) = (Vxc / η, Vyc / ξ).

According to another aspect of the invention, there is provided an optical switch control method comprising: selecting at least one optical input unit that inputs input light; at least one optical output unit that outputs output light; and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to an x-axis used in the above-mentioned and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged opposite to the mirror, and applying an electrode voltage to the electrodes And a control variable calculation step of calculating a control variable Vt corresponding to a target light intensity, the method comprising: a drive control unit that rotates the mirror about the x axis and the y axis. And an axial voltage calculation step for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and y-axis from the control variable Vt, and an electrode voltage to be applied to each electrode from Vx and Vy. And, an electrode voltage control step of applying the electrode voltage to the corresponding _{electrode, (Vx 0, Vy 0)} Vx-Vy coordinates on a plane where the light loss becomes a minimum, and the (Vxd, Vyd) Vx When an arbitrary coordinate on the −Vy plane, L is the length of the trajectory through which Vt from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd) passes, the axial voltage Vx is Vx = (− Vxd / L ² ) · It is expressed by (Vt−L) ² + Vxd + Vx ₀ , and the shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ .

According to another aspect of the invention, there is provided an optical switch control method comprising: selecting at least one optical input unit that inputs input light; at least one optical output unit that outputs output light; and an optical input unit or an optical output unit. A mirror device having a mirror rotatably supported with respect to an x-axis used in the above-mentioned and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged opposite to the mirror, and applying an electrode voltage to the electrodes And a control variable calculation step of calculating a control variable Vt corresponding to a target light intensity, the method comprising: a drive control unit that rotates the mirror about the x axis and the y axis. And an axial voltage calculation step for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and y-axis from the control variable Vt, and an electrode voltage to be applied to each electrode from Vx and Vy. And an electrode voltage control step for applying this electrode voltage to the corresponding electrode. The electrode controls electrodes a and b for controlling the rotation of the mirror about the x axis and the rotation of the mirror about the y axis. And (Vx ₀ , Vy ₀ ) are coordinates on the Vx-Vy plane where the optical loss is minimum, (Vxd, Vyd) is arbitrary coordinates on the Vx-Vy plane, and L is The length of the trajectory through which Vt from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd) passes, the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, and the electrode c is applied Assuming that the electrode voltage to be applied is Vc and the electrode voltage applied to the electrode d is Vd, the shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb. is, the axial voltage Vy ^{is, Vy = (Vyd / L 2} ) · Vt 2 + Vy 0 and V = It is characterized in that represented by Vc-Vd.

  In the optical switch control method, the control variable calculation step may acquire the control variable Vt corresponding to the target optical loss based on the correspondence between the light intensity stored in advance and the control variable Vt. . In the control variable calculation step, the control variable Vt corresponding to the target light loss is calculated based on the approximate expression of the control variable Vt that approximates the correspondence between the light intensity stored in advance and the control variable Vt. It may be.

According to the present invention, the voltage Vx is expressed by a quadratic function Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and the shaft voltage Vy is expressed by a quadratic function Vy = (Vyd / L ² ) · Vt ² + Vy _0. Crosstalk and Rabbit Ear can be suppressed by calculating based on this and rotating the mirror based on the calculated voltage. Accordingly, an arithmetic unit or the like for performing a complicated calculation using a third-order or higher function is not required, and thus it is possible to realize crosstalk and Rabbit Ear suppression at a low cost.

It is a figure which shows typically the structure of the optical switch which concerns on the 1st Embodiment of this invention. It is a figure which shows the locus | trajectory of the control variable Vt in the normalized shaft voltage. It is a figure which shows the locus | trajectory of Vt when making the point (0.43, 0.06) in FIG. 2 into the range of Vt. It is a figure which shows the locus | trajectory of Vt when making the point (0.85, 0.38) in FIG. 2 into the range of Vt. It is a figure which shows the locus | trajectory of Vt when making the point (0.96, 0.64) in FIG. 2 into the range of Vt. It is a figure for demonstrating the setting method of the control variable Vt. It is a figure which shows the locus | trajectory of Vt on a Vx-Vy plane. It is a figure which shows the relationship between Vt and a loss. It is a figure which shows typically the structure of the optical switch which concerns on the 2nd Embodiment of this invention. It is a figure which shows typically the structure of an Add type | mold wavelength selective switch. It is a figure which shows typically the structure of a Drop type | mold wavelength selective switch. It is the figure which simplified the wavelength selective switch of FIG. (A) is a figure which shows the structure of a mirror, (b) is a figure which shows the structure of a MEMS mirror apparatus, (c) is a figure which shows the rotation of the mirror around the x-axis in a MEMS mirror apparatus, (d) is a MEMS mirror. It is a figure which shows rotation around the y-axis of the mirror in an apparatus. It is a loss contour map in case the peak for N port exists. It is a loss contour map on the Vx-Vy plane. It is a figure which shows the transmittance | permeability of the Vx direction in FIG. 12A. It is a figure which shows the transmittance | permeability of the Vy direction in FIG. 12A. It is a loss contour map on the Vx-Vy plane in the case of switching a rotating shaft. It is a figure which shows the transmittance | permeability and loss of Vt in FIG. 13A. It is a figure which shows the locus | trajectory of Vt on the loss contour line at the time of introduce | transducing a high-order function. It is a figure which shows the transmittance | permeability and loss of Vt in FIG. 14A.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described. The optical switch according to the present embodiment controls the rotation of the mirror of the optical switch by proportional control (P control), which is basic control of PID control, using the control variable Vt. The drive control unit 400 of the optical switch 100 described with reference is replaced with a drive control unit 10 described later. Therefore, in the following, the same components and components as those of the optical switch 100 are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

<Configuration of optical switch>
As shown in FIG. 1, the optical switch 1 according to the present embodiment includes a spatial optical system switch unit 300 and a drive control unit 10 that controls the operation of the MEMS mirror device 104 included in the spatial optical system switch unit 300. Consists of The drive control unit 10 includes an O / E converter 11 including a photodiode that converts optical power branched from an output port using a coupler 110 into an electrical signal, and the electrical converted by the O / E converter 11. An A / D converter 12 that digitally converts the signal and obtains a value of the light intensity of the output light of the optical signal based on the branched optical power, and the light intensity of the output light obtained by the A / D converter 12 A comparator 13 for obtaining a difference between the target value and the target value (hereinafter referred to as a deviation), a compensation amount calculating unit 14 for obtaining a compensation amount proportional to the deviation, and a compensation amount calculated by the compensation amount calculating unit 14 as a control variable Vt. An adder 15 for negative feedback, a delay unit 16 comprising a memory for holding the control variable Vt to which the compensation amount has been added for an arbitrary control period ΔT in preparation for the next P control, and a compensation amount Control variable with The calculation unit 17 that calculates the shaft voltages Vx and Vy from Vt, and the electrode mirrors Va, Vb, Vc, and Vd from the shaft voltages Vx and Vy calculated by the calculation unit 17 to obtain the MEMS mirror of the spatial optical system switch unit 300 An electrode voltage control unit 18 to be applied to the device 104 and a timer 19 for executing P control at an arbitrary period ΔT.

  The drive control unit 10 includes a microprocessor such as a CPU / FPGA / ASIC, a control memory, and its peripheral circuits. The drive control unit 10 reads and executes the operation program stored in the control memory, thereby executing the hardware and the operation program. In cooperation, the above-described A / D conversion unit 12, comparator 13, compensation amount calculation unit 14, adder 15, delay unit 16, calculation unit 17, electrode voltage control unit 18, and timer 19 are realized.

  Here, the calculation unit 17 calculates the shaft voltage (Vx, Vy) from the control variable Vt based on the following expressions (7) and (8).

Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ (7)
Vy = (Vyd / L ² ) · Vt ² + Vy ₀ (8)

Here, (Vxd, Vyd) is an appropriate coordinate on the Vx-Vy voltage plane, and L is the length of the trajectory through which the control variable Vt passes from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd). . As an example, FIG. 2 shows the locus of Vt when (Vxd, Vyd) = (1, 1) and the above equations (7) and (8) are represented on the Vx-Vy voltage plane.

In FIG. 2, the locus of the control variable Vt is a region where the control variable Vt is small compared to Vy = Vx ^α where Vy is a higher-order function of Vx, for example, Vx = 0 to 0 if the region is indicated by Vx. In the range of about .8, it approaches a locus of α = 3 (third-order equation) or less, and in the region where the control variable Vt is close to (1, 1), it approaches a locus of a higher order function. Therefore, of the trajectories from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd), how much higher-order function shape trajectory is approximated is adjusted by determining the range used for control by the control variable Vt. be able to.

  For example, as shown in FIG. 3A, if the range of the control variable Vt is up to a point (0.43, 0.06) on the locus of the control variable Vt according to the equations (7) and (8), the locus of the graph is two. Approximate the shape of the next function. Similarly, as shown in FIG. 3B, if the range up to the point (0.85, 0.38) on the locus of the control variable Vt is the range of the control variable Vt, the locus of the graph approximates a cubic function shape. Similarly, as shown in FIG. 3C, if the range up to the point (0.96, 0.64) on the trajectory of the control variable Vt is the range of the control variable Vt, the trajectory of the graph approximates a quartic function shape.

  As described above, in this embodiment, the axis voltage Vx is also converted into a quadratic function using the control variable Vt, so that it is possible to take a trajectory similar to the trajectory of the higher-order function without using only the quadratic function. It becomes.

  Regarding the amount of change of the shaft voltages Vx and Vy with respect to the control variable Vt, that is, the differential value, in the case of the above formulas (5) and (6) where only the shaft voltage Vy is a higher-order function of the V control variable t, It is expressed by equations (9) and (10).

dVx / dVt = A (9)
dVy / dVt = αB · Vt ^α-1 (10)

  On the other hand, when the above equations (7) and (8) in the present embodiment are applied, they are represented by the following equations (11) and (12).

dVx / dVt = (− 2Vxd / L ² ) · (Vt−L) (11)
dVy / dVt = (2Vyd / L ² ) · Vt (12)

  Thus, in the present embodiment, the differential value is a linear expression of the control variable Vt. Here, when Expressions (9) and (10) in which only the shaft voltage Vy is a high-order function of the control variable Vt are compared with Expressions (11) and (12) in the present embodiment, Expressions (9) and (12) are compared. In (10), the differential value of the shaft voltage Vy increases with an (α−1) -order higher-order function as the control variable Vt increases. On the other hand, in equations (11) and (12), the differential value of the shaft voltage Vx is proportional to (Vt−L), and the differential value of the shaft voltage Vy is proportional to the control variable Vt, so the control variable Vt is small. By the way, the change of the control variable Vt appears linearly as a change on the Vx side, and as the control variable Vt approaches L, the change of the control variable Vt appears linearly as a change on the Vy side. For this reason, in the case where the locus of the control variable Vt is matched with a higher-order function shape whose degree is α = 3 or more, in this embodiment, the amount of change in the axial voltages Vx and Vy becomes extremely large in a region where the control variable Vt is large. You don't have to. As a result, in the present embodiment, the amount of change in the shaft voltages Vx and Vy with respect to the control variable Vt does not become extremely large while taking the locus of the high-order function, and the loss characteristic with respect to the control variable Vt is also a quadratic function. It becomes equivalent to the case.

  As a result, the mirror can be rotated along the locus of the high-order function shape without changing the shaft voltage Vy to a high-order function of α ≧ 3 of the control variable Vt, and even in a region where the control variable Vt is large. Since the change amount of the shaft voltage Vy does not increase nonlinearly, the control parameter Vt is not switched in the middle of Vt while suppressing the Rabbit Ear while keeping the loss characteristic of the control variable Vt below the allowable value. In addition, the output power can be easily controlled.

<Operation of optical switch>
Next, the operation of the optical switch 1 according to the present embodiment will be described with reference to FIG.

  When the optical signal is branched from the output port by the coupler 10, the optical signal is converted into an electric signal by the O / E converter 11, converted into a digital signal by the A / D converter 12, and the light intensity of the output light. Is calculated.

  When the light intensity of the output light of the optical signal is calculated, the comparator 13 calculates a deviation between the light intensity of the output light and the target value of the light intensity of the output light.

  When the deviation is calculated, the compensation amount calculation unit 14 calculates a compensation amount proportional to the deviation. When the output power is smaller than the target value by the deviation e, the compensation amount calculation unit 14 adds a compensation amount Kp times the deviation e to the control variable Vt. The sign of the compensation amount at the time of addition is a sign that increases the output by adding the compensation amount to the control variable Vt. By appropriately setting the value of Kp, when there is a deviation e, the control variable Vt is corrected so as to cancel the deviation e, so that the output power finally approaches the target value.

  When the compensation amount is calculated, the adder 15 adds the compensation amount to the control variable Vt so as to be negatively fed back. At this time, the delay unit 16 holds the control variable Vt to which the compensation amount is added for the next P control, and holds the control variable Vt for an arbitrary control period ΔT timed by the timer 19.

  When the compensation amount is added to the control variable Vt, the calculation unit 17 calculates the shaft voltages Vx and Vy from the control variable Vt. An example of the locus of the axial voltage (Vx, Vy) of the mirror 1041 calculated by the calculation unit 17 is shown in FIG. By using the control variable Vt as shown in FIG. 4, the shaft voltages Vx and Vy are calculated. Details of the method for setting the control variable Vt will be described later.

  When the axial voltages Vx and Vy are calculated, the electrode voltage control unit 18 uses the axial voltages Vx and Vy to apply to the electrodes 1042a to 1042d in the MEMS mirror device 104 of the spatial optical system switch unit 300. Vc and Vd are calculated and applied to the corresponding electrodes 1042a to 1042d. As a result, the mirror 1041 having two rotation axes of the MEMS mirror device 104 can be controlled by one control variable Vt, so that the operation of the mirror that achieves both reduction of crosstalk and suppression of Rabbit Ear can be performed. Thus, it can be realized seamlessly and continuously without rapidly changing the direction of the mirror as in the conventional method.

<Setting method of control variable Vt>
Next, details of the method of setting the control variable Vt will be described with reference to FIG.

  When the port of interest is Port x, the loss contours of Port x are almost concentric ellipses, and the same loss contours of Port x-1 and Port x + 1 are arranged on both sides thereof. The trajectory of the control variable Vt must cross an ellipse (thick solid line in FIG. 4) representing the maximum loss of the required loss variable range. Further, crosstalk in which light leaks to the adjacent port by changing the control variable Vt needs to be suppressed to an allowable value (adjacent crosstalk) or less. For this reason, the trajectory of the control variable Vt must not cross an ellipse (an alternate long and short dash line in FIG. 4) that gives adjacent crosstalk of adjacent ports. In addition to these two conditions, it is desirable that the locus of the control variable Vt passes (Vxc, Vyc) in FIG. In the present embodiment, (Vxc, Vyc) is referred to as a cross point because it is an intersection of an ellipse of variable loss range and an ellipse that gives adjacent crosstalk. Since this cross point is a point on the outermost ellipse of the use loss range, it can be said that the use range of the control variable Vt is determined.

Here, whether the locus connecting the origins (Vx ₀ , Vy ₀ ) and (Vxc, Vyc) is approximated to a quadratic function curve, a cubic function curve, or a higher order curve. As described above, is determined by where (Vxc, Vyc) for determining the range of Vt is determined on the locus connecting (Vx ₀ , Vy ₀ ) and (Vxd, Vyd). Therefore, as shown in the following equation (13), the ratio of Vxc and Vxd is η, and how much higher-order function curve is approximated is determined according to the value of η.

η = Vxc / Vxd (13)

  As a guideline for η, a locus is close to a quadratic function curve when η≈0.4, a cubic function curve when η≈0.85, and a quaternary function curve when η≈0.95. Further, ξ is obtained from η using the following equation (14).

ξ = 2−η−2 (1-η) ^1/2 (14)

  Note that (η, ξ) indicates a cross point on the normalized voltage plane where (Vxd, Vyd) = (1, 1), and the above equation (14) is Vx = η, Vy = ξ. , Vxd = Vyd = 1, and the equations (7) and (8) are used simultaneously to obtain ξ.

  ξ, Vyc, and Vyd also have the relationship shown in the following equation (15) similar to equation (7).

ξ = Vyc / Vyd (15)

  Therefore, when (Vxc, Vyc) and η are determined, (Vxd, Vyd) can be obtained by the following equation (16) from equations (13) to (15).

(Vxd, Vyd) = (Vxc / η, Vyc / ξ) (16)

When L is finally determined, equations (7) and (8) are determined, and the control variable Vt is calculated. Here, L can take an arbitrary value. As described above, L represents the length of the trajectory through which Vt from (Vx ₀ , Vy ₀ ) to (Vxd, Vyd) passes, and this length may be calculated. At this time, Vt, Vx, and Vy have the same scale, that is, Vt = 1 does not have to have the same length as Vx = 1 or Vy = 1 on the Vx-Vy voltage plane.

As an example, the straight line distance (shortest distance) from the origin (Vx ₀ , Vy ₀ ) to the cross point (Vxc, Vyc) so as to be the same as the above formulas (3) and (4) is the value of Vt at the cross point. The case where it is determined to be will be described. Here, when the linear distance is Lc, this Lc is expressed by the following equation (17).

Lc = (Vxc ² + Vyc ² ) ^1/2 (17)

  Here, the following expression (18) is established between Lc and L.

Lc / L = ξ ^1/2 (18)

  From the above equations (17) and (18), L can be obtained from the following equation (19).

L = Lc / ξ ^1/2 = {(Vxc ² + Vyc ² ) / ξ} ^1/2 (19)

  Thus, by determining the cross point (Vxc, Vyc) determined from the loss contour of the optical switch and η determining the shape of the trajectory, the equations (14), (16), (19) to (Vxd, Vyd) L is determined, and equations (7) and (8) are determined.

  Formula (19) is an example, and the same scale may be used as defined, or Lc may be defined according to another rule and obtained from Formula (18).

  The thus obtained (Vxd, Vyd) and L are stored in a non-volatile memory or the like in the control circuit not shown in FIG. 1 and read out when necessary to obtain the shaft voltage (Vx , Vy).

<About simulation results>
5A and 5B, assuming the function of loss (Loss [dB]) of the following equation (13), when the mirror is moved according to the present embodiment, on the quadratic function curve and on the quadratic function curve The simulation result when moving the mirror to pass is shown. In FIGS. 5A and 5B, symbol a indicates the present embodiment, symbol b indicates a quadratic function curve, and symbol c indicates a quartic function curve.

Loss (Vx, Vy) = (20 / 67.08) {(10 Vx) ² + Vy ² }
... (18)

  Here, it is assumed that the cross point (Vxc, Vyc) = (3, 60), and each curve always passes through the cross point. In this embodiment, η = 0.95 (value targeting a locus close to a quartic function). Normally, the loss is expressed by a negative value, but here, the sign is omitted and expressed by a positive value.

  As shown in FIG. 5A, the locus in the present embodiment is close to the locus of a quartic function. In particular, near the cross point where the loss is large, it almost coincides with the locus of the quartic function.

  Regarding the relationship between the control variable Vt and the optical loss, as shown in FIG. 5B, it can be said that the linearity is so high that the differential value of the loss with respect to the control variable Vt does not change, but the linearity in the present embodiment is a quadratic function. The change of the differential value is smaller than that of the linearity, and the change in the differential value is smaller, indicating that the linearity is the highest and the controllability is good. On the other hand, in the case of a quartic function, the slope is greatly different between Vt = 0 to 40 [V] and Vt = 50 to 60 [V], and the PID control parameter is switched around Vt = 45 [V]. It is better to set.

  As described above, according to the present embodiment, the calculation unit 17 causes the mirror 1041 to rotate around the x axis and the y axis by a predetermined amount from the control variable Vt based on the above equations (7) and (8). Axial voltages Vx and Vy to be moved are calculated, and a drive voltage applied to each of the electrodes is calculated from the Vx and Vy by the electrode voltage control unit 18 and applied to the electrodes corresponding to the drive voltage, and a comparator 13, the deviation of the detection result with respect to the target value is obtained, the adder 15 adds a compensation amount corresponding to the deviation to the control variable Vt, and negatively feeds back the deviation to the control variable Vt. Since it is possible to control the operation of the mirror having one control variable Vt without using a higher order function, the operation of the mirror that achieves both the reduction of crosstalk and the suppression of Rabbit Ear It can be realized seamlessly and continuously without abruptly changing the mirror orientation. As a result, it is possible to reduce crosstalk and suppress Rabbit Ear at a lower cost.

  Needless to say, the present embodiment using one control variable Vt can also be applied to I control and D control of PID control.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described. The present embodiment does not have a mirror rotation control function based on negative feedback control, and other configurations are the same as those of the first embodiment described above. Therefore, in the present embodiment, the same names and symbols are assigned to the same components as those in the first embodiment described above, and the description thereof is omitted as appropriate.

  As shown in FIG. 6, the optical switch 2 according to the present embodiment includes a spatial optical system switch unit 300 and a drive control unit 20 that controls the operation of the MEMS mirror device 104 included in the spatial optical system switch unit 300. Consists of The drive control unit 20 includes a Vt calculation unit 21, a calculation unit 17, and an electrode voltage control unit 18.

  Here, the Vt calculation unit 21 includes a data table storing the value of the control variable Vt with respect to the optical loss, or an approximate expression representing the relationship between the optical loss and the control variable Vt, and is based on the target value of the optical loss. A control variable Vt is calculated.

  Thus, when the control variable Vt is calculated by the Vt calculation unit 21, the calculation unit 17 calculates the shaft voltages Vx and Vy from the control variable Vt as in the first embodiment described above. When the axial voltages Vx and Vy are calculated, the electrode voltage control unit 18 applies the electrode voltages Va and Vb to be applied to the electrodes 1042a to 1042d in the MEMS mirror device 104 of the spatial optical system switch unit 300 from the axial voltages Vx and Vy. , Vc, and Vd are applied to the corresponding electrodes 1042a to 1042d. Thereby, the loss of the optical signal which has a wavelength corresponding to a mirror can be made into a predetermined range.

  As described above, according to the present embodiment, the control variable Vt corresponding to the target loss is calculated by the Vt calculation unit 21, and the mirror 1041 is moved from the control variable Vt to the x-axis and the y-axis by the calculation unit 17. The shaft voltages Vx and Vy to be rotated around are calculated based on the above formulas (7) and (8), and the drive voltage applied to each electrode is calculated from the Vx and Vy by the electrode voltage control unit 18. By applying the corresponding voltage, the loss of the optical signal having the wavelength corresponding to the mirror can be suppressed within a predetermined range. Thus, since the shaft voltage (Vx, Vy) can be obtained by a low-order function using one control variable Vt, the variable accuracy and calculation load due to not using a high-order function are reduced. Since a high-performance computing unit is not required, crosstalk and Rabbit Ear can be suppressed at a low cost.

  In the first and second embodiments described above, the case of an Add type wavelength selective switch has been described as an example. However, the present invention can also be applied to a Drop type wavelength selective switch as shown in FIG.

  The present invention can be applied to various devices that control the rotation of a reflecting member that can rotate around two axes, such as a MEMS mirror device.

  DESCRIPTION OF SYMBOLS 1, 2 ... Optical switch 10, 20 ... Drive control part, 11 ... O / E converter, 12 ... A / D converter, 13 ... Comparator, 14 ... Compensation amount calculation part, 15 ... Adder, 16 ... Delay unit, 17 ... calculation unit, 18 ... electrode voltage control unit, 19 ... timer, 21 ... Vt calculation unit, 101, 101-1 to 101-n ... input side optical fiber, 102, 102-1 to 102-n ... Output side optical fiber, 103 ... diffraction grating, 104 ... MEMS mirror device, 105 ... duplexer, 106-1 to 106-m ... photodiode, 107 ... A / D converter. DESCRIPTION OF SYMBOLS 108 ... Mirror control circuit, 109 ... Merger, 110 ... Coupler, 300 ... Spatial optical system switch part, 1041 ... Mirror, 1042a-1042d ... Electrode.

Claims (14)

At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x axis and the y axis; and
An optical switch comprising: a detection unit that detects light intensity of output light output from the light output unit;
The drive control unit
A control variable calculator for calculating a control variable Vt corresponding to the target light intensity;
An axial voltage calculation unit for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and the y-axis, respectively, from the control variable Vt;
An electrode voltage controller for calculating an electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and applying the electrode voltage to the corresponding electrode;
A comparison unit for obtaining a deviation between the detection result detected by the detection unit and the target light intensity;
A compensation unit that adds a compensation amount according to the deviation output from the comparison unit to the control variable Vt, and negatively feeds back the deviation to the control variable Vt.
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is the lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from the above (Vx ₀ , Vy ₀ ). If the length of the trajectory through which the Vt passes to the (Vxd, Vyd) is,
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ ,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ . At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x axis and the y axis; and
A detection unit for detecting the light intensity of the output light output from the light output unit;
A demultiplexing unit for demultiplexing the output light detected by the detection unit for each wavelength,
The drive control unit
A photoelectric conversion unit that converts the output light demultiplexed by the demultiplexing unit into an electrical signal;
An A / D converter that digitally converts the electrical signal and outputs a value of the light intensity of the output light;
A comparison unit for obtaining a deviation between a value of the light intensity of the output light and a target value of the light intensity;
A compensation amount calculation unit for obtaining a compensation amount proportional to the deviation output from the comparison unit;
An adding unit for adding the compensation amount to the control variable Vt so as to negatively feed back;
A delay unit for holding the control variable Vt to which the compensation amount is added for an arbitrary control period;
An axial voltage calculator for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and the y-axis, respectively, from the control variable Vt to which the compensation amount has been added;
An electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage controller for applying the electrode voltage to the corresponding electrode,
The electrodes include electrodes a and b for controlling the rotation of the mirror about the x-axis and electrodes c and d for controlling the rotation of the mirror about the y-axis,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is the lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from the above (Vx ₀ , Vy ₀ ). The length of the trajectory through which the Vt passes to (Vxd, Vyd), the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, and the electrode voltage applied to the electrode c Is Vc, and the electrode voltage applied to the electrode d is Vd,
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd. The optical switch according to claim 1 or 2,
On the Vx-Vy plane, the (Vx _0, Vy ₀₎ in the range where crosstalk occurs from the light output section adjacent to the maximum range and the optical output of the light loss in the light output section corresponding When the coordinates of the intersection are (Vxc, Vyc) and arbitrary constants ξ and η are expressed by ξ = 2−η−2 (1-η) ^1/2 , (Vxd, Vyd) is (Vxd, Vyd) = (Vxc / η, Vyc / ξ). At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x-axis and the y-axis, respectively.
The drive control unit
A control variable calculation unit for calculating a control variable Vt corresponding to the target optical loss;
An axial voltage calculation unit for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and the y-axis, respectively, from the control variable Vt;
An electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage control unit to apply the electrode voltage to the corresponding electrode, and
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is minimum, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is the above (Vx ₀ , Vy ₀ ). And the length of the trajectory through which the Vt passes from (Vxd, Vyd) to
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ ,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ . At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x-axis and the y-axis, respectively.
The drive control unit
A control variable calculation unit for calculating a control variable Vt corresponding to the target optical loss;
An axial voltage calculation unit for calculating axial voltages Vx and Vy for rotating the mirror about the x-axis and the y-axis, respectively, from the control variable Vt;
An electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage control unit to apply the electrode voltage to the corresponding electrode, and
The electrodes include electrodes a and b for controlling the rotation of the mirror about the x-axis and electrodes c and d for controlling the rotation of the mirror about the y-axis,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is the lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from the above (Vx ₀ , Vy ₀ ). The length of the trajectory through which the Vt passes to (Vxd, Vyd), the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, and the electrode voltage applied to the electrode c Is Vc, and the electrode voltage applied to the electrode d is Vd,
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd. The optical switch according to claim 4 or 5,
A storage unit that stores in advance the correspondence between the optical loss and the control variable Vt;
The optical switch, wherein the control variable calculation unit acquires a control variable Vt corresponding to the target light intensity from the storage unit. The optical switch according to claim 4 or 5,
A storage unit preliminarily storing an approximate expression of the control variable Vt that approximates the correspondence between the optical loss and the control variable Vt;
The control variable calculation unit calculates a control variable Vt corresponding to the target light intensity based on the approximate expression stored in the storage unit. At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x axis and the y axis; and
A method of controlling an optical switch comprising: a detection unit that detects the light intensity of output light output from the light output unit;
A control variable calculating step for calculating a control variable Vt corresponding to the target light intensity;
An axial voltage calculating step of calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis from the control variable Vt;
An electrode voltage control step of calculating an electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and applying this electrode voltage to the corresponding electrode;
A comparison step for obtaining a deviation between the detection result detected by the detection unit and the target light intensity;
A compensation step of adding a compensation amount according to the deviation output from the comparison unit to the control variable Vt, and negatively feeding back the deviation to the control variable Vt,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is minimum, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is the above (Vx ₀ , Vy ₀ ). And the length of the trajectory through which the Vt passes from (Vxd, Vyd) to
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ ,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ . At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x axis and the y axis; and
A detection unit for detecting the light intensity of the output light output from the light output unit;
And a demultiplexing unit that demultiplexes the output light detected by the detection unit for each wavelength.
A photoelectric conversion step of converting the output light demultiplexed by the demultiplexing unit into an electrical signal;
An A / D conversion step of digitally converting the electrical signal and outputting a value of light intensity of the output light;
A comparison step for obtaining a deviation between a light intensity value of the output light and a target value of the light intensity;
A compensation amount calculating step for obtaining a compensation amount proportional to the deviation output by the comparison step;
An adding step of adding the compensation amount to the control variable Vt so as to negatively feed back;
A delay step of holding the control variable Vt to which the compensation amount has been added for an arbitrary control period;
An axial voltage calculating step of calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis, respectively, from the control variable Vt to which the compensation amount has been added;
Calculating an electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage control step of applying the electrode voltage to the corresponding electrode,
The electrodes include electrodes a and b for controlling the rotation of the mirror about the x-axis and electrodes c and d for controlling the rotation of the mirror about the y-axis,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is the lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from the above (Vx ₀ , Vy ₀ ). The length of the trajectory through which the Vt passes to (Vxd, Vyd), the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, and the electrode voltage applied to the electrode c Is Vc, and the electrode voltage applied to the electrode d is Vd,
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd. The method of controlling an optical switch according to claim 8 or 9,
On the Vx-Vy plane, the (Vx _0, Vy ₀₎ in the range where crosstalk occurs from the light output section adjacent to the maximum range and the optical output of the light loss in the light output section corresponding When the coordinates of the intersection are (Vxc, Vyc) and arbitrary constants ξ and η are expressed by ξ = 2−η−2 (1-η) ^1/2 , (Vxd, Vyd) is (Vxd, Vyd) = (Vxc / η, Vyc / ξ). A method for controlling an optical switch. At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x-axis and the y-axis, respectively.
A control variable calculating step for calculating a control variable Vt corresponding to the target light intensity;
An axial voltage calculating step of calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis from the control variable Vt;
Calculating an electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage control step of applying the electrode voltage to the corresponding electrode,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is minimum, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is the above (Vx ₀ , Vy ₀ ). And the length of the trajectory through which the Vt passes from (Vxd, Vyd) to
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ ,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ . At least one light input section for inputting input light;
At least one light output unit for outputting output light;
A mirror supported to be rotatable with respect to an x-axis used for selecting the light input unit or the light output unit and a y-axis orthogonal to the x-axis, and a plurality of electrodes arranged to face the mirror A mirror device having
A drive control unit that applies an electrode voltage to the electrode to rotate the mirror about the x-axis and the y-axis, respectively.
A control variable calculating step for calculating a control variable Vt corresponding to the target light intensity;
An axial voltage calculating step of calculating axial voltages Vx and Vy for rotating the mirror about the x axis and the y axis from the control variable Vt;
Calculating an electrode voltage to be applied to each of the electrodes from the Vx and the Vy, and an electrode voltage control step of applying the electrode voltage to the corresponding electrode,
The electrodes include electrodes a and b for controlling the rotation of the mirror about the x-axis and electrodes c and d for controlling the rotation of the mirror about the y-axis,
(Vx ₀ , Vy ₀ ) is a coordinate on the Vx-Vy plane where the optical loss is the lowest, (Vxd, Vyd) is an arbitrary coordinate on the Vx-Vy plane, and L is from the above (Vx ₀ , Vy ₀ ). The length of the trajectory through which the Vt passes to (Vxd, Vyd), the electrode voltage applied to the electrode a is Va, the electrode voltage applied to the electrode b is Vb, and the electrode voltage applied to the electrode c Is Vc, and the electrode voltage applied to the electrode d is Vd,
The shaft voltage Vx is expressed by Vx = (− Vxd / L ² ) · (Vt−L) ² + Vxd + Vx ₀ and Vx = Va−Vb,
The shaft voltage Vy is expressed by Vy = (Vyd / L ² ) · Vt ² + Vy ₀ and Vy = Vc−Vd. The method of controlling an optical switch according to claim 11 or 12,
The control variable calculating step acquires the control variable Vt corresponding to the target optical loss based on the correspondence between the light intensity stored in advance and the control variable Vt. Method. The method of controlling an optical switch according to claim 11 or 12,
The control variable calculation step calculates a control variable Vt corresponding to the target light loss based on an approximate expression of the control variable Vt that approximates the correspondence between the light intensity stored in advance and the control variable Vt. A method for controlling an optical switch.

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