JP4828571B2 - Optical switch control method and apparatus - Google Patents

Description

  The present invention provides an optical switch that continuously reflects a light beam input from an arbitrary input port between a plurality of input / output ports by a plurality of MEMS (Micro Electric Mechanical System) mirrors and outputs the light beam to an arbitrary output port. The present invention relates to an optical switch control method and apparatus for performing angle control of a plurality of MEMS mirrors that determine an output path of a light beam and stabilizing output light intensity at an output port.

  FIG. 5 shows a configuration example of the optical switch. In FIG. 5, the optical switch has a configuration in which two collimator arrays 1 and 2 in which a plurality of collimators are two-dimensionally arranged and two MEMS mirror arrays 3 and 4 in which a plurality of mirrors are two-dimensionally arranged. An input optical fiber array in which a plurality of optical fibers are two-dimensionally arranged corresponding to each collimator (input port) is connected to the input-side collimator array 1, and each collimator array 2 is connected to the output-side collimator array 2. An output optical fiber array in which a plurality of optical fibers are two-dimensionally arranged corresponding to (output port) is connected. In addition, the angle of each mirror is controlled by MEMS technology, and any input / output optical fiber can be connected (switching the output path) by a combination of mirrors reflected by the two MEMS mirror arrays 3 and 4. .

Here, the optical switch for connecting the input and output optical fibers finely adjusts the angle of each mirror as needed so that the optimum output light intensity is obtained for each output port. As a conventional adjustment method, a mirror is driven by superimposing a perturbation voltage (RF component) of a predetermined frequency on an applied voltage (DC component) that sets the angle of each mirror, and the output light intensity of each output port of the optical switch Is detected and the angle of each mirror is adjusted to optimize the output light intensity (Patent Document 1). For example, in the differential drive method, a light intensity differential value is obtained from the mirror drive (rotation) amount when the mirror to be adjusted is finely driven (rotated) and the light beam intensity at the drive position, and this light intensity differential value is obtained. Then, the next moving target position is calculated from the predetermined step amount, and the mirror is adjusted to the optimum position by sequentially moving the mirror to the target position. In the circular drive method, the mirror is driven so that the light beam reflected from the mirror draws an annular trajectory, and the intensity of the light beam at an arbitrary angle during the circular drive is detected. The angle at which the intensity is detected is calculated, and the procedure for adjusting the mirror to that angle is sequentially repeated to adjust the mirror to a position where the light beam is maximized.
JP 2004-271977 A

  By the way, during the output light intensity stabilization control that measures the output light intensity of each output port of the optical switch and stabilizes the output light intensity of each output port by adjusting the angle of the plurality of mirrors, for example, the light intensity of the input signal light May vary for some reason, or if each mirror of the optical switch vibrates due to an external factor or failure, the output light intensity being measured may periodically vary. When the fluctuation of the output light intensity matches the perturbation frequency, the output light intensity stabilization control becomes unstable, and there is a problem that the output light intensity is not stable.

  In the output light intensity stabilization control using a perturbation voltage of a predetermined frequency, the present invention malfunctions when the output light intensity fluctuation shows an abnormal value exceeding the normal value range associated with the output light intensity stabilization control. An object of the present invention is to provide an optical switch control method and apparatus that can prevent fluctuations in output light intensity due to the above.

  The first invention is applied to an optical switch that continuously reflects a light beam input from an arbitrary input port between a plurality of input / output ports by a plurality of mirrors, and outputs the light beam to an arbitrary output port. A mirror is driven by superimposing a perturbation voltage (RF component) of a predetermined frequency on an applied voltage (DC component) that sets an angle of a plurality of mirrors to be connected, and the output light intensity at each output port is detected to detect the mirror angle. In an optical switch control device that controls the output light intensity while adjusting the output, a perturbation voltage obtained by synthesizing at least two frequencies is used as a perturbation voltage, and a light intensity signal for each perturbation frequency is extracted from the output light intensity. Select a perturbation frequency that is within the normal range where fluctuations in the light intensity signal at each perturbation frequency are expected, and control the stabilization of the output light intensity based on the light intensity signal at that perturbation frequency. Provided with the means to carry out.

  The second invention is applied to an optical switch that continuously reflects a light beam input from an arbitrary input port between a plurality of input / output ports by a plurality of mirrors and outputs the light beam to an arbitrary output port. A mirror is driven by superimposing a perturbation voltage (RF component) of a predetermined frequency on an applied voltage (DC component) that sets an angle of a plurality of mirrors to be connected, and the output light intensity at each output port is detected to detect the mirror angle. In the optical switch control method for controlling the output light intensity while adjusting the output, a perturbation voltage obtained by synthesizing at least two frequencies is used as the perturbation voltage, and a light intensity signal for each perturbation frequency is extracted from the output light intensity. Select a perturbation frequency that is within the normal range where fluctuations in the light intensity signal at each perturbation frequency are expected, and control the stabilization of the output light intensity based on the light intensity signal at that perturbation frequency. Do.

  Here, when there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, an arbitrary one of the perturbation frequencies is selected from the perturbation frequency, and the output light intensity using the light intensity signal. The stabilization control may be performed. Alternatively, when there are one or more perturbation frequencies within the normal range where the fluctuation of the light intensity signal is assumed, one perturbation frequency is selected from among the perturbation frequencies set in advance, and the light intensity signal is used. Then, stabilization control of the output light intensity may be performed. Alternatively, when the perturbation frequency is 1 or more within the normal range where the fluctuation of the light intensity signal is assumed, stabilization control of the output light intensity is performed using the light intensity signal obtained by synthesizing the light intensity signal of the perturbation frequency. It may be done.

  In order to control the output light intensity of the optical switch using the MEMS mirror to be constant, it is necessary to finely adjust the angle of the MEMS mirror as needed.

  In the present invention, when the perturbation voltage applied to the mirror is a composite of a plurality of frequencies, and it is determined that the light intensity signal at a certain perturbation frequency has an effect on the stabilization operation of the output light intensity, the perturbation frequency The output intensity stabilization control is performed by removing the light intensity signal. Thereby, for example, even when an input intensity fluctuation at a specific frequency occurs, output intensity stabilization control using a light intensity signal of a perturbation frequency that is not easily affected is realized, and an excessive output intensity fluctuation can be suppressed.

FIG. 1 shows an embodiment of an optical switch control device of the present invention.
In FIG. 1, the optical switch 10 shows only one set of mirrors 11 and 12 between the input port 8 and the output port 9, and the mirror of this set of mirrors 11 and 12 is used as the optical switch control device of this embodiment. A mechanism for controlling the angle and stabilizing the output light intensity will be described.

  The output light intensity stabilization control unit 21 outputs an applied voltage (DC component) that initially sets the mirror angle of the mirrors 11 and 12, and the perturbation voltage application unit 22 outputs perturbation voltages (RF components) having frequencies f1 to fn, respectively. They are superposed, combined by the combining unit 23 and input to the mirror angle control units 24 and 25. n is an integer of 2 or more. The mirror angle controllers 24 and 25 control the mirror angles of the mirrors 11 and 12 according to the applied voltage (DC component + RF component).

  The output light intensity measurement unit 27 receives the output light from the output port 9 via the optical coupler 26 and detects the output light intensity. This light intensity signal is n-branched by the branching unit 28, and the light intensity components corresponding to the perturbation frequencies f 1 to fn are extracted by the perturbation component extraction unit 29 and input to the output light intensity stabilization control unit 21. The output light intensity stabilization control unit 21 evaluates whether or not the light intensity fluctuations of the perturbation frequencies f1 to fn are within the allowable range, and based on the light intensity of the perturbation frequency where the light intensity fluctuation is within the normal range. The applied voltage (DC component) that determines the mirror angle of the mirrors 11 and 12 is feedback-controlled.

FIG. 2 shows a processing procedure in the embodiment of the optical switch control device of the present invention.
First, an applied voltage (DC component) that determines the mirror angle of the mirrors 11 and 12 is initially set (S1). Next, a perturbation voltage (RF component) having frequencies f1 to fn is superimposed on the applied voltage (DC component) of the mirrors 11 and 12, and an applied voltage (DC component + RF component) is generated by combining them (S2). Next, the mirrors 11 and 12 are driven by the applied voltage (DC component + RF component) (S3), and the output light intensity is detected (S4).

  Next, it extracts to each light intensity component of perturbation frequency f1-fn from a light intensity signal (S5), and determines whether the light intensity fluctuation | variation for each perturbation frequency f1-fn is settled in the tolerance | permissible_range (S6). ). Next, a perturbation frequency in which the light intensity fluctuation is within the normal range is selected, the output light intensity is evaluated based on the light intensity signal of the perturbation frequency (S7), and the applied voltage for controlling the mirror angle of the mirrors 11 and 12 (DC component) is reset (S8), and the process returns to the process of superimposing the perturbation voltage (RF component) in step S2. By repeating the above processing, by removing the perturbation frequency components that have abnormal light intensity fluctuations due to internal factors or disturbance factors, the output light intensity is stabilized based on the output light intensity of the perturbation frequency where the light intensity fluctuation is within the normal range. Control can be performed.

  Here, a method for determining whether or not the light intensity fluctuations of the perturbation frequencies f1 to fn are within the allowable range in step S6 and selecting the perturbation frequency in which the light intensity fluctuations are in the normal range in step S7 is shown in FIG. This will be described with reference to FIG.

  The light intensity fluctuation is judged as normal or abnormal by comparing the detected light intensity waveform with the assumed light intensity waveform and its allowable range of ± ΔdB, and the detected light intensity waveform is assumed. If it exceeds the permissible range, “abnormal” is determined, and if it is within the permissible range, “normal” is determined. In FIG. 3, the light intensity fluctuations of the perturbation frequencies f1 and fn are within the allowable range and determined as “normal”, and the light intensity fluctuation of the perturbation frequency f2 exceeds the allowable range and is determined as “abnormal”. Show. If the perturbation frequency at which the light intensity fluctuation indicates “normal” is 1 or more, the perturbation frequency used for the output light intensity stabilization control is selected according to the following three patterns.

Pattern 1: One arbitrary perturbation frequency is selected from the “normal” perturbation frequencies, and the light intensity signal is used as an evaluation target.
Pattern 2: From the “normal” perturbation frequency, one perturbation frequency based on the order set in advance is selected, and the light intensity signal is set as the evaluation target. The order set in advance is, for example, the order of low or high perturbation frequency.
Pattern 3: All of the “normal” perturbation frequencies are selected, and the combined light intensity waveform is evaluated.

  If there is no perturbation frequency at which the light intensity fluctuation indicates “normal” and all indicate “abnormal”, processing corresponding to the following three patterns is performed.

Pattern 4: All perturbation frequencies are not adopted, and the perturbation voltage is applied again without adjusting the mirror angle (return to step S1 in FIG. 2).
Pattern 5: One perturbation frequency is selected from “abnormal” perturbation frequencies based on the order set in advance, and the light intensity waveform is selected as an evaluation target. The order set in advance is, for example, the order of low or high perturbation frequency.
Pattern 6: All “abnormal” perturbation frequencies are selected, and the synthesized light intensity waveform is evaluated.

  Note that the pattern 4 is usually used, and the patterns 5 and 6 are adopted when improvement cannot be expected even if the pattern 4 is reset for some reason, for example, when an abnormality factor is known in advance.

  Further, as shown in FIG. 4, when it is known in advance that the light intensity fluctuation including the frequency fx is generated when an abnormality occurs in the device connected to the input port 8 of the optical switch 10, the following is performed. Is possible. When the fluctuation of the light intensity at the frequency fx indicates “abnormal”, an alarm is displayed as an abnormality has occurred in the device connected to the input port 8 of the optical switch 10, thereby causing a failure outside the system or a failure within the system. Can be separated. Then, the perturbation frequency may be selected by excluding the perturbation frequency fx.

The figure which shows embodiment of the optical switch control apparatus of this invention. The flowchart which shows the process sequence in embodiment of the optical switch control apparatus of this invention. The figure explaining the selection method of the perturbation frequency in which light intensity fluctuation | variation exists in a normal range. The figure which shows the operation example of the optical switch control apparatus of this invention. The figure which shows the structural example of an optical switch.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Collimator array 3, 4 MEMS mirror array 8 Input port 9 Output port 10 Optical switch 11, 12 Mirror 21 Output light intensity stabilization control part 22 Perturbation voltage application part 23 Synthesis | combination part 24, 25 Mirror angle control part 26 Optical coupler 27 Output light intensity measurement unit 28 Branch unit 29 Perturbation component extraction unit

Claims (8)

This is applied to an optical switch that continuously reflects a light beam input from an arbitrary input port between multiple input / output ports by multiple mirrors and outputs it to an optional output port. Driving the mirror by superimposing a perturbation voltage (RF component) of a predetermined frequency on the applied voltage (DC component) for setting the angle, detecting the output light intensity at each output port and adjusting the mirror angle to output light In the optical switch control device that performs control to stabilize the strength,
A perturbation voltage obtained by synthesizing at least two frequencies is used as the perturbation voltage, a light intensity signal for each perturbation frequency is extracted from the output light intensity, and the fluctuation of the light intensity signal at each perturbation frequency is within a normal range that is assumed. An optical switch control device comprising: means for selecting a perturbation frequency and performing stabilization control of the output light intensity based on a light intensity signal of the perturbation frequency. The optical switch control device according to claim 1,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, an arbitrary one of the perturbation frequencies is selected from the perturbation frequencies, and the light intensity signal is used to determine the output light intensity. An optical switch control device characterized by being configured to perform stabilization control. The optical switch control device according to claim 1,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, one perturbation frequency is selected from among the perturbation frequencies set in advance, and the light intensity signal is used. An optical switch control device characterized by being configured to perform stabilization control of the output light intensity. The optical switch control device according to claim 1,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, stabilization control of the output light intensity is performed using a light intensity signal obtained by combining the light intensity signals of the perturbation frequency. An optical switch control device characterized by being configured to perform. This is applied to an optical switch that continuously reflects a light beam input from an arbitrary input port between multiple input / output ports by multiple mirrors and outputs it to an optional output port. Driving the mirror by superimposing a perturbation voltage (RF component) of a predetermined frequency on the applied voltage (DC component) for setting the angle, detecting the output light intensity at each output port and adjusting the mirror angle to output light In the optical switch control method for performing control to stabilize the intensity,
A perturbation voltage obtained by synthesizing at least two frequencies is used as the perturbation voltage, a light intensity signal for each perturbation frequency is extracted from the output light intensity, and the fluctuation of the light intensity signal at each perturbation frequency is within a normal range that is assumed. An optical switch control method comprising: selecting a perturbation frequency and performing stabilization control of the output light intensity based on a light intensity signal of the perturbation frequency. The optical switch control method according to claim 5,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, an arbitrary one of the perturbation frequencies is selected from the perturbation frequencies, and the light intensity signal is used to determine the output light intensity. An optical switch control method characterized by performing stabilization control. The optical switch control method according to claim 5,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, one perturbation frequency is selected from among the perturbation frequencies set in advance, and the light intensity signal is used. Stabilizing control of the output light intensity is performed. An optical switch control method, comprising: The optical switch control method according to claim 5,
When there is one or more perturbation frequency within the normal range where the fluctuation of the light intensity signal is assumed, stabilization control of the output light intensity is performed using a light intensity signal obtained by combining the light intensity signals of the perturbation frequency. An optical switch control method characterized by comprising:

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