JP4106599B2 - Operation method of optical switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a method for operating an optical switch suitable for configuring an optical signal switch, an optical signal switching device, an optical signal cross-connect, and the like arranged at a cross point of an optical communication network.
[0002]
[Prior art]
The transmission bandwidth in optical communication is steadily increasing, and coupled with the progress of wavelength multiplexing technology, it is about to be increased in speed and capacity, and the optical fiber network in the backbone communication network. In order to construct a hardware infrastructure, a connection switching device for switching the destination of an optical signal is required.
[0003]
In recent years, as an optical switch constituting such a switching device, an optical switch that uses optical deflection has appeared. For example, in the optical switch disclosed in Japanese Patent Laid-Open No. 2000-180905 (first document), The electrode is a single crystal substrate, an optical waveguide showing the electro-optic effect is formed thereon, a prism-type electrode for light deflection is formed thereon, and a thin film lens for collimating light is further provided. In addition, the optical path between the input and output ports is switched by controlling the voltage applied to the prism type electrode.
[0004]
Further, in the optical switch disclosed in Japanese Patent Laid-Open No. 2001-242396 (second document), a rotatable mirror is disposed at two positions between the input port and the output port, and the rotation angle of the mirror is controlled. The optical path is switched, and this is called a micro rotating mechanical (MEMS) type.
[0005]
Normally, in an optical switch that uses optical deflection in free space, the optical signal is stably connected to the output port. Therefore, the deflection angle is adjusted according to the degree of optical coupling, and the combined light intensity is adjusted by the deflection element. Tracking is performed to feed back to a drive parameter (for example, voltage) and control it to an appropriate value.
[0006]
For example, in the method of controlling the light deflection direction with voltage, when switching a plurality of light paths, control is performed to change the voltage applied to the electrodes of the individual light deflection elements simultaneously and independently. Thus, the switching time can be shortened.
[0007]
However, tracking control is applied when signal light is incident on the output side port in a transient state of voltage change, and an optical path may be set in an incorrect combination.
[0008]
3A and 3B are main part plan views showing an optical switch for explaining an erroneous connection at the time of switching an optical path, where FIG. 3A is a setting state (current state) of an optical path, and FIG. (C) shows an erroneous connection in an optical path setting switching transition state.
[0009]
In the figure, 1A, 2A, 3A and 4A are input side ports, 5 is an input side micro lens (first micro lens), 1B, 2B, 3B and 4B are input side optical deflection elements, and 6 is a slab. Waveguides, 1C, 2C, 3C, and 4C are output side optical deflection elements, 7 is an output side micro lens (second micro lens), and 1D, 2D, 3D, and 4D are output side ports. Here, the light deflection element is assumed to be one described in the first document.
[0010]
In FIG. 3A, 1-3 is an optical path connecting the input side port 1A and the output side port 3D, and 2-4 is an optical path connecting the input side port 2A and the output side port 4D. -2 indicates an optical path connecting the input side port 3A and the output side port 2D, and 4-1 indicates an optical path connecting the input side port 4A and the output side port 1D.
[0011]
As can be understood from the above description regarding the symbol of the optical path seen in FIG. 3A, the symbol is represented by MN, M and N are both positive integers, and M is the order of the input port. N represents the order of the output side ports, and therefore, the symbol of the optical path connecting the input side port 1A and the output side port 1D is 1-1. Hereinafter, another figure, that is, FIG. The same applies to B) and (C).
[0012]
It can be understood that (A) and (B) in FIG. 3 are compared, but all the optical paths in the set state of (A) are switched except for the optical path 3-2 connecting the input side port 3A and the output side port 2D. It is scheduled.
[0013]
3A, for example, the optical path 1-3 connecting the input side port 1A and the output side port 3D and the input side port 4A and the output side port 1D are connected. Each of the optical paths 4-1, as planned to be seen in FIG. 3B, has an optical path 1-4 connecting the input side port 1 A and the output side port 4 D with the optical path 1-3. In addition, the optical path 4-1 is switched to become an optical path 4-3 connecting the input side port 4A and the output side port 3D.
[0014]
Therefore, now, the voltage applied to the optical deflection element 3C is changed, and the state connected by the optical path 1-3 shown in FIG. 3C is indicated by the arrow (1). The light path 4-3 is switched so that light from the light can be received and connected by the optical path 4-3. At the same time, the voltage applied to the optical deflection element 2B is changed, and the optical path 2 shown in FIG. The state connected by -4 must be switched so that light can be emitted to the optical deflecting element 1C as indicated by the arrow (2), and the state must be connected by the optical path 2-1.
[0015]
However, in the middle of the switching indicated by the arrows {circle around (1)} and {circle around (2)}, there is a condition that makes it possible to establish an optical path connecting the input side port 2A and the output side port 3D. When a situation where both the optical element and the optical deflection element 3C are simultaneously satisfied occurs, an undesired optical path 2-3 is set, and feedback control for optimizing the optical power is working in the output side port 3D. In this case, the optical path 2-3 established erroneously is controlled so as to be maintained as it is.
[0016]
[Problems to be solved by the invention]
In the present invention, when an optical switch that is optically connected is operated by switching and setting an optical path that connects between a plurality of light deflecting means on the input side and a plurality of light deflecting means on the output side, An attempt is made to prevent an optical path from being set by a simple operation method.
[0017]
[Means for Solving the Problems]
In the operation method of the optical switch according to the present invention, the input light from the input side port (for example, the input side ports 1A to 4A) is converted into the first optical deflection means (for example, the first optical deflection elements 1B to 4B, The first light deflecting movable mirrors 11B to 14B) are deflected by the second light deflecting means (for example, second light deflecting elements 1C to 4C, second light deflecting movable mirrors 11C to 14C). In the optical switch that guides the output light to the output side port (for example, the output side ports 1D to 4D) as the output light between the first light deflecting means and the second light deflecting means when the optical path is switched. switch by shifting the driving timing, after the switching, the first light deflecting means or the second is based on performing tracking control with respect to the optical deflection means in accordance with the degree of optical coupling of the input light and the output light It has become.
[0018]
By adopting the above means, when switching the optical switch, feedback that increases the power of optical coupling, that is, tracking control is added, and the malfunction that the incorrect connection between the input and output ports is performed is completely eliminated. Can be prevented.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a main part plan view showing an optical switch for explaining an operation method at the time of switching an optical path according to the first embodiment of the present invention, and FIG. 1 (A) is a set state before switching of an optical path ( (Current state), (B) is the output side, that is, the state where the voltage of the second optical deflection element group is switched, and (C) is the state where the voltage is switched of the input side, ie, the first optical deflection element group. (Switching complete state) is shown, and the same symbol as that used in FIG. 3 represents the same part or has the same meaning. The first and second optical deflection elements used in the present invention may be the same as the optical deflection element having a prism type electrode described as the prior art.
[0020]
FIG. 1A is exactly the same as FIG. 3A illustrating the prior art. Therefore, an optical path 1-3 is provided between the input side port 1A and the output side port 3D. The optical path 2-4 is between the side port 2A and the output side port 4D, the optical path 3-2 is between the input side port 3A and the output side port 2D, and the optical path 4- is between the input side port 4A and the output side port 1D. It is tied with 1 respectively.
[0021]
Here, the setting in FIG. 1A is switched to the same setting as the switching schedule shown in FIG. 3B, that is, only the optical path 3-2 connecting the input side port 3A and the output side port 2D is maintained as it is. The optical path 1-4 is set between the input side port 1A and the output side port 4D, the optical path 2-1 is set between the input side port 2A and the output side port 1D, and the input side port 4A and the output side Switching is performed so as to set the optical path 4-3 with the port 3D.
[0022]
Switching Operation (1) The voltage to be applied to the electrode of each light deflection element is determined from the information regarding the current setting state seen in FIG. 1A and the information concerning the switching schedule seen in FIG. The value of the voltage is calculated from the light deflection angle required in each light deflection element.
[0023]
(2) As seen in FIG. 1B, a voltage determined for each electrode of the output side optical deflection element (second optical deflection element) group is applied.
[0024]
At this time, at the output side port where the optical path is switched, although light is incident on the output side micro lens (second micro lens), the deflection angle in the output side optical deflection element is indicated by an arrow. Therefore, light is not coupled to the output port.
[0025]
(3) As shown in FIG. 1C, a voltage determined for each electrode of the input side optical deflection element (first optical deflection element) group is applied.
[0026]
At this time, the optical path further changes as indicated by the arrow, and the input side port and the output side port to which the optical path is switched are connected to some extent, and a part of the input light can be detected. However, depending on the channel, that is, the optical path, the coupling strength may vary.
[0027]
(4) In order to optimize the light intensity at each output side port, tracking control, that is, fine adjustment of the electrode applied voltage to the input side optical deflection element or the output side optical deflection element is performed.
[0028]
In the above-described operation method, the applied voltage is set for the second optical deflection element group, that is, the output side optical deflection element group, but the applied voltage setting for the first optical deflection element group is performed first. The operation procedure to be performed can be switched in the same manner.
[0029]
In the first embodiment described above, the case of an optical switch based on an optical deflection element having a prism-type electrode whose optical deflection angle is changed by applying a voltage has been described. However, the present invention is movable. The same can be applied to an optical switch that deflects light using a mirror.
[0030]
FIG. 2 is a plan view of an essential part for explaining an optical switch which is a target of optical path switching according to the second embodiment of the present invention. In the figure, reference numerals 11A, 12A, 13A and 14A denote input side optical fibers. , 15 is a collimator lens, 11B, 12B, 13B, and 14B are first light deflection movable mirrors, 11C, 12C, 13C, and 14C are second light deflection movable mirrors, 17 is a condenser lens, and 11D, 12D, and 13D. , 14D indicate output side optical fibers, respectively.
[0031]
In this optical switch, the first and second light deflecting movable mirrors rotate to change the light deflection angle to switch the optical signal between channels, that is, between ports.
[0032]
The collimator lens and the condensing lens have a structure in which lenses made of glass or resin are integrated in an array, and are arranged and fixed so as to be optically coupled to each of the optical fibers.
[0033]
The light deflection movable mirror is a MEMS mirror in which a large number of movable mirrors are integrated on a common silicon substrate by applying micromachine technology.
[0034]
In the optical switch of FIG. 2 also, when switching the optical path, optical coupling occurs undesirably between undesired ports in the process of changing the direction of each optical deflecting movable mirror, and the optical coupling power. The possibility that an optical path is set by adding feedback to increase the frequency is exactly the same as in the first embodiment, and therefore, the rotation timing of the first and second light deflecting movable mirror groups can be changed by shifting the rotation timing. Similar to the first embodiment, the problem can be avoided.
[0035]
In both the first and second embodiments described above, it is necessary to apply a voltage so as to shift the drive timing of the first light deflector and the second light deflector. In addition, it is preferable that the applied voltage can be changed at different voltage increments so that coarse adjustment and fine adjustment are possible. First, the first light deflecting means and the second light deflecting means Any one of the light deflection means may be driven with the coarse adjustment applied voltage, then the other is driven with the coarse adjustment applied voltage, and finally one of them may be driven with the fine adjustment applied voltage.
[0036]
【The invention's effect】
In the operation method of the optical switch according to the present invention, the input light from the input side port is deflected by the first light deflecting means, and the deflected light is further deflected by the second light deflecting means. In the optical switch for guiding the output light to the output side port, the drive timing of the first light deflecting means and the second light deflecting means is shifted at the time of switching the optical path, and after the switching , the input light and Basically, tracking control is performed on the first light deflecting means or the second light deflecting means in accordance with the degree of optical coupling of the output light .
[0037]
By adopting the above configuration, when switching the optical switch, the feedback that increases the power of optical coupling, that is, the tracking control is added, and the malfunction that the erroneous connection between the input and output ports is established. It can be completely prevented.
[Brief description of the drawings]
FIG. 1 is a plan view of a principal part illustrating an optical switch for explaining an operation method when switching an optical path according to a first embodiment of the present invention.
FIG. 2 is a plan view of an essential part for explaining an optical switch that is a target of optical path switching according to a second embodiment of the present invention;
FIG. 3 is a main part plan view showing an optical switch for explaining an erroneous connection at the time of switching an optical path.
[Explanation of symbols]
1A, 2A, 3A, 4A Input side port 5 Input side micro lens (first micro lens)
1B, 2B, 3B, 4B Input side optical deflection element 6 Slab waveguide 1C, 2C, 3C, 4C Output side optical deflection element 7 Output side micro lens (second micro lens)
1D, 2D, 3D, 4D Output side port 11A, 12A, 13A, 14A Input side optical fiber 15 Collimator lens 11B, 12B, 13B, 14B First light deflection movable mirror 11C, 12C, 13C, 14C Second light Deflection mirror 17 Condensing lens 11D, 12D, 13D, 14D Output side optical fiber

Claims (4)

In an optical switch that deflects input light from an input side port by first optical deflecting means, further deflects the deflected light by second optical deflecting means, and guides the deflected light as output light to an output side port ,
When the optical path is switched, the drive timing of the first light deflecting means and the second light deflecting means is shifted and switched ,
A method of operating an optical switch , wherein after the switching, tracking control is performed on the first light deflecting unit or the second light deflecting unit in accordance with the degree of optical coupling between the input light and the output light. . In between the input and output channels, and a second light deflection element group first microphone Rollet lens group and the first light deflection element group corresponding to each channel corresponding to each channel also through the slab waveguide first optically coupled can disposed on the second microphone Rollet lens group, and the optical switch in the first optical deflecting elements and the second optical deflecting elements by changing the deflection angle of the optical switching the optical paths between the input and output channels In
When the optical path is switched, the drive voltage application timing of the first optical deflection element and the second optical deflection element is shifted, and after the switching , the first optical deflection element or the second optical deflection element or the second optical deflection element is switched according to the degree of optical coupling. A method for operating an optical switch, comprising performing tracking control on two optical deflection elements . In order to coarsely and finely adjust the light deflection angle depending on the first light deflecting means or the second light deflecting means, means for changing the applied voltage at different voltage increments is used. Either the first light deflecting means or the second light deflecting means is driven with the roughly adjusted applied voltage, and the other is then driven with the roughly adjusted applied voltage. Further, the first light deflecting means or the second light deflecting means is driven. 2. The method for operating an optical switch according to claim 1, wherein either one of the optical switches is driven with a finely adjusted applied voltage. In order to coarsely and finely adjust the light deflection angle depending on the first light deflection element or the second light deflection element, means for changing the applied voltage at different voltage increments is used, and the first light deflection is performed at the time of switching the optical path. One of the element and the second light deflection element is driven with a roughly adjusted applied voltage, the other is then driven with a roughly adjusted application voltage, and the first light deflection element or the second light deflection element is further driven. 3. The optical switch operating method according to claim 2, wherein either one of the optical switches is driven with a finely adjusted applied voltage.

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