JP4066805B2 - Optical switch device and optical transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical switch device and an optical transmission system used in wavelength division multiplexing (WDM) optical communication or the like.
[0002]
[Prior art]
As an optical switch device used in a WDM optical communication system, for example, there is a wavelength switching switch described in Non-Patent Document 1. This wavelength change-over switch can be reduced in size and cost by combining a plurality of input / output ports formed of optical fibers and lenses, a diffraction grating, and a MEMS mirror.
[0003]
[Non-Patent Document 1]
OFC 2002 Postdeadline Papers, FB7-1, Wavelength-selective 1 × 4 switch for 128 WDM channels at 50 GHz spacing
[0004]
[Problems to be solved by the invention]
However, the above prior art has the following problems. That is, since the MEMS mirror is driven only in the direction of switching the input / output optical path of the input / output port, when switching the input / output optical path of the input / output port, the optical signal reflected by the MEMS mirror crosses the adjacent input / output port. Sometimes. In this case, since unnecessary light enters the adjacent input / output port, the transmission quality of the optical signal passing through the input / output port deteriorates.
[0005]
An object of the present invention is to provide an optical switch device and an optical transmission system capable of reducing the influence on an optical signal passing through another input / output port when the input / output optical path of the input / output port is switched.
[0006]
[Means for Solving the Problems]
The present invention provides an optical switch device comprising a plurality of input / output ports for inputting / outputting optical signals and a switch means for switching input / output optical paths of the input / output ports, wherein the switch means is one of the plurality of input / output ports. An optical component that reflects an optical signal input from the input / output port toward another input / output port, first drive means for driving the optical component to switch the input / output optical path of the input / output port, and an optical signal have a second driving means for driving the optical component to move between a position for reflecting in the direction deviated from the position and direction of the optical signal to the input and output ports to be reflected in a direction towards the input port, The optical component is tiltably provided on the cantilever beam supported by the base, the first drive means is a means for tilting the optical component with respect to the cantilever beam, and the second drive means is a tilt of the optical component. Different from direction Is characterized in that a means for moving the optical component in the direction.
[0007]
In such an optical switch device of the present invention, when the input / output optical path of the input / output port is switched, the light is first reflected from the position (normal position) where the optical signal is reflected in the direction toward the input / output port by the second driving means. The optical component is moved to a position (reflecting position) where the signal is reflected in a direction shifted from the direction toward the input / output port. Subsequently, the optical component is driven by the first driving means so that the input / output optical path of the input / output port is switched. Thereafter, the optical component is returned from the retracted position to the normal position by the second driving means. As described above, the optical component is moved to the retracted position by the second driving unit in advance, and then the optical component is driven by the first driving unit to switch the input / output optical path of the input / output port. In the middle of the switching, the optical signal reflected by the optical component does not cross other input / output ports that are not to be switched. Accordingly, since light leaking to other input / output ports is reduced, the influence on the optical signal passing through the input / output ports can be reduced. Furthermore, the structure of the switch means having the optical component, the first drive means, and the second drive means can be simplified.
[0008]
Preferably, the optical system further includes an optical demultiplexing element for demultiplexing the wavelength multiplexed optical signal input from the input / output port for each wavelength, and the switch means includes an optical component corresponding to each signal light demultiplexed for each wavelength. Have more than one. As a result, since the optical switch device of the present invention can be used as a wavelength switching switch, an optical ADM (Add Drop Multiplexer) or the like for adding or dropping a signal of an arbitrary wavelength from wavelength-multiplexed optical signals can be simply configured. Can be realized.
[0010]
In this case, preferably, the first driving means has a first electrode provided on the base and a first voltage source for supplying a voltage to the first electrode, and the second driving means is provided on the base. A second electrode; and a second voltage source for supplying a voltage to the second electrode. In this case, since the optical component is driven by an electrostatic force, it is possible to save almost no current and to save power.
[0013]
Preferably, the switching time of the input / output optical path of the input / output port is 10 ms or less. As a result, when the input / output optical path of the input / output port is switched, light is less likely to leak to other input / output ports that are not to be switched, so that the influence on the optical signal passing through the input / output port can be further reduced. .
[0014]
Preferably, when the input / output optical path of the input / output port is switched, the crosstalk to the other input / output port is −25 dB or less. As a result, there is almost no influence on the optical signal passing through other input / output ports that are not to be switched.
[0015]
An optical transmission system according to the present invention includes the optical switch device described above. Accordingly, as described above, when the input / output optical path of the input / output port is switched in the optical switch device, the influence on the optical signal passing through the other input / output port that is not the switching target can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of an optical switch device and an optical transmission system according to the present invention will be described below with reference to the drawings.
[0017]
1 and 2 are schematic configuration diagrams showing an embodiment of an optical switch device according to the present invention. In each figure, for convenience of explanation, an xyz orthogonal coordinate system and an xy′z ′ orthogonal coordinate system are shown. FIG. 1 is a diagram when the optical switch device is viewed in the y-axis and y′-axis directions, and FIG. 2 is a diagram when the optical switch device is viewed in the x-axis direction.
[0018]
In each figure, the optical switch device 1 of the present embodiment includes a plurality of input / output optical fibers 2a to 2f, an array lens 3, a diffraction grating 4, a lens 5, and an optical switch array 6. . An xyz orthogonal coordinate system is used in the optical system between the input / output optical fibers 2 a to 2 f and the diffraction grating 4, and an xy′z ′ orthogonal coordinate system is used in the optical system between the diffraction grating 4 and the optical switch array 6. Is used.
[0019]
The input / output optical fibers 2a to 2f are input / output ports for inputting / outputting multiplexed optical signals (wavelength multiplexed optical signals) of, for example, four wavelengths λ _{1 to} λ ₄ and are arranged in parallel in the z-axis direction. . Here, the input / output optical fiber 2c is used as a common incident port, the input / output optical fiber 2d is used as a common output port, the input / output optical fibers 2a and 2e are used as Add ports, and the input / output optical fibers 2b and 2f are used. Is used as a drop port.
[0020]
The array lens 3 collimates the optical signals input from the input / output optical fibers 2a, 2c, and 2e and outputs the collimated optical signals to the diffraction grating 4, and collects the optical signals from the diffraction grating 4 to collect the input / output optical fibers 2b, 2b, Output to 2d and 2f.
[0021]
Diffraction grating 4, by diffraction at the diffraction angle corresponding to wavelength division multiplexed signal light from the array lens 3 to the respective wavelengths lambda ₁ to [lambda] _4, and demultiplexing the wavelength-multiplexed signal light for each wavelength lambda ₁ to [lambda] ₄ Output to the lens 5. Although the diffraction grating 4 in the figure is a transmission type, a reflection type diffraction grating may be used.
[0022]
Lens 5 outputs the optical signal of the diffraction grating 4 at demultiplexed wavelength lambda ₁ to [lambda] every ₄ to the optical switch array 6 is focused, diffracted collimates the optical signal from the optical switch array 6 grating 4 is output.
[0023]
The optical switch array 6 includes movable mirrors 7a to 7d (hereinafter sometimes collectively referred to as the movable mirror 7) that reflect the optical signals having wavelengths λ _{1 to} λ ₄ collected by the lens 5, respectively. The input / output optical paths of the output optical fibers 2a to 2f are switched.
[0024]
3 is a plan view showing a part of the optical switch array 6, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. In each figure, the optical switch array 6 has a substrate 8 made of Si or the like, and a plurality of actuator units 9 formed on the substrate 8 by using a micro electro mechanical system (MEMS) technique.
[0025]
Each actuator unit 9 has a cantilever 11 that is cantilevered via a spacer 10 on the upper surface of the substrate 8, and an annular support 12 is provided at the tip of the cantilever 11. The movable mirror 7 is supported on the annular support portion 12 via hinges 13 on both sides. The hinge 13 extends in the longitudinal direction of the cantilever 11 so that the movable mirror 7 can tilt with respect to an axis (y ′ axis) parallel to the longitudinal direction of the cantilever 11 (see FIG. 6). At the tip of the cantilever 11, a comb tooth portion 14 is provided.
[0026]
As shown in FIG. 5, a pair of substantially semicircular electrodes 15 a and 15 b for tilting the movable mirror 7 with respect to the annular support portion 12 are provided on the upper surface of the substrate 8 facing the movable mirror 7. Is provided. Further, a comb-like electrode for moving the movable mirror 7 in a direction different from the tilting direction of the movable mirror 7 by bending the cantilever 11 is provided in the vicinity of the comb tooth portion 14 on the upper surface of the substrate 8. 16 is provided.
[0027]
Such an actuator portion 9 is made of, for example, conductive Si. The reflecting surface of the movable mirror 7 is coated with, for example, Au so that the light from the lens 5 is almost totally reflected.
[0028]
The cantilever 11 and the electrodes 15a and 15b are connected via a voltage source 17, and by supplying a voltage to the electrodes 15a and 15b from the voltage source 17, the movable mirror 7 and the electrodes 15a and 15b are connected to each other. An electrostatic force is generated to tilt the movable mirror 7 with respect to the annular support 12 of the cantilever 11.
[0029]
At this time, when the voltage applied to the electrodes 15a and 15b is zero, the movable mirror 7 is in parallel with the annular support 12 as shown in FIG. In this state, the movable mirror 7 reflects the optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (common output port) 2d.
[0030]
On the other hand, when a predetermined voltage is applied to the electrode 15a, as shown in FIG. 6B, the electrode 15a side portion of the movable mirror 7 is attracted to the electrode 15a by the electrostatic force generated between the movable mirror 7 and the electrode 15a. The movable mirror 7 tilts with respect to the annular support portion 12. In this state, the movable mirror 7 reflects the optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (Drop port) 2f.
[0031]
When a predetermined voltage is applied to the electrode 15b, the electrode 15b side portion of the movable mirror 7 is attracted to the electrode 15b by the electrostatic force generated between the movable mirror 7 and the electrode 15b as shown in FIG. 6C. The movable mirror 7 tilts in the opposite direction with respect to the annular support portion 12. In this state, the movable mirror 7 reflects the optical signal from the input / output optical fiber (common incident port) 2c toward the input / output optical fiber (Drop port) 2b.
[0032]
The cantilever 11 and the electrode 16 are connected via a voltage source 18, and an electrostatic force is generated between the comb tooth portion 14 and the electrode 16 by supplying a voltage to the electrode 16 by the voltage source 18. And bend the tip end portion of the cantilever 11 downward.
[0033]
At this time, when the voltage applied to the electrode 16 is zero, as shown in FIG. 4, the cantilever 11 is in a state of extending straight. In this state, the movable mirror 7 transmits the optical signal guided from the input / output optical fibers 2a, 2c, and 2e through the array lens 3, the diffraction grating 4, and the lens 5 to the lens 5, the diffraction grating 4, and the array lens 3. Through the input / output optical fibers 2b, 2d, and 2f.
[0034]
On the other hand, when a predetermined pulse voltage is applied to the electrode 16, as shown in FIG. 7, the comb tooth portion 14 is attracted to the electrode 16 by the electrostatic force generated between the comb tooth portion 14 and the electrode 16, and the cantilever 11. The front end side portion is bent downward, and accordingly, the movable mirror 7 moves in a direction different from the tilting direction of the movable mirror 7 (see FIG. 6). As a result, the movable mirror 7 transmits the optical signals guided from the input / output optical fibers 2a, 2c, 2e through the array lens 3, the diffraction grating 4, and the lens 5 from the direction toward the input / output optical fibers 2b, 2d, 2f. Move to the retreat position where it reflects off the direction.
[0035]
Next, the operation of the optical switch device 1 configured as described above will be described. The wavelength multiplexed optical signal input from the input / output optical fiber (common incident port) 2c is collimated by the array lens 3 and incident on the diffraction grating 4, and is demultiplexed for each of the wavelengths λ _{1 to} λ ₄ . The optical signals having the wavelengths λ _{1 to} λ ₄ are reflected by the movable mirrors 7 a to ₇ d of the optical switch array 6 while being collected by the lens 5.
[0036]
At this time, in a state where the voltage applied by the voltage sources 17 and 18 of the optical switch array 6 is zero, the positions (postures) of the movable mirrors 7a to 7d are the normal positions as shown in FIG. The tilt angle of 7d is 0 degrees as shown in FIG.
[0037]
In this case, the optical signals of the wavelengths λ _{1 to} λ ₄ reflected by the movable mirrors _{7 a to} 7 d are incident on the diffraction grating 4 and are combined while being collimated by the lens 5. The combined optical signal is output from the input / output optical fiber (common output port) 2d in a state of being collected by the array lens 3. Thereby, at the time of a power failure, the wavelength multiplexed optical signal input from the input / output optical fiber 2c is output as it is from the input / output optical fiber 2d.
[0038]
Here, when wavelength switching is performed so that, for example, only an optical signal having a wavelength λ ₄ out of the wavelength multiplexed optical signal input from the input / output optical fiber 2c is output from the input / output optical fiber (Drop port) 2b, first, the wavelength is changed. in the actuator unit 9 having a movable mirror 7d for reflecting optical signals of lambda _4, a pulse voltage is applied by the voltage source 18 to the electrode 16. Then, as shown in FIG. 7, the tip end side of the cantilever 11 of the actuator unit 9 bends downward, and the movable mirror 7d moves from the normal position to the standby position. As a result, the optical axis of the optical signal having the wavelength λ ₄ reflected by the movable mirror 7d is shifted from the optical axis of the optical signal having the wavelength λ ₁ to ₃ reflected by the movable mirror 7d. Accordingly, the optical signal having the wavelength λ ₄ reflected by the movable mirror 7d is not incident on the lens 5 and does not reach the input / output optical fiber 2d.
[0039]
In this state, in the actuator section 9 having the movable mirror 7d, a predetermined voltage is applied to the electrode 15b by the voltage source 17, and the movable mirror 7d is tilted in the direction as shown in FIG. _The input / output optical fiber 2b is selected as the output port of the optical signal ₄ .
[0040]
Subsequently, the voltage applied to the electrode 16 is set to zero. Then, the cantilever 11 returns to the initial state as shown in FIG. 4 by the biasing force, and the movable mirror 7d returns from the standby position to the normal position. In this case, the optical signal of wavelength λ ₄ reflected by the movable mirror 7d is collimated by the lens 5, diffracted by the diffraction grating 4, and output from the input / output optical fiber 2b in a state of being collected by the array lens 3. Is done.
[0041]
By the way, when the actuator portion 9 does not have the comb tooth portion 14, the electrode 16, and the voltage source 18, in the above wavelength switching, the movable mirror 7d is held at the normal position shown in FIG. The tilt angle will change. That is, in the state where the optical signal having the wavelength λ ₄ reflected by the movable mirror 7d is incident on the input / output optical fiber 2d, the output optical path of the optical signal having the wavelength λ ₄ is changed from the input / output optical fiber 2d to the input / output optical fiber 2b. It will be switched.
[0042]
In this case, since the optical signal having the wavelength λ ₄ reflected by the movable mirror 7d crosses the input / output optical fiber (common incident port) 2c between the input / output optical fibers 2d and 2b, it is unnecessary for the input / output optical fiber 2c. An optical signal enters. Therefore, the optical signal passing through the input / output optical fiber 2c is affected, and the transmission quality is significantly deteriorated.
[0043]
On the other hand, in the present embodiment, the movable mirror 7d is moved from the normal position shown in FIG. 4 to the retracted position shown in FIG. 7, and the tilt angle of the movable mirror 7d is changed in this state. When the output optical path is switched to the optical fiber 2b, the optical signal having the wavelength λ ₄ reflected by the movable mirror 7d does not cross the input / output optical fiber 2c. Therefore, almost no unnecessary light leaks to the input / output optical fiber 2c, so that it is possible to prevent deterioration of the transmission quality of the optical signal passing through the input / output optical fiber 2c.
[0044]
At this time, in order to more reliably prevent light leakage to the input / output optical fiber 2c, the input / output optical path switching time is preferably 10 ms or less. In addition, when the input / output optical path is switched, the intensity of the optical signal leaking to the input / output optical fiber 2c (crosstalk to the input / output optical fiber 2c) is preferably −25 dB or less.
[0045]
FIG. 8 shows a configuration of an optical ADM as an example of an optical transmission system including the optical switch device 1 described above.
[0046]
In the figure, an optical ADM 20 has the optical switch device 1 described above. A multiplexer 21 is connected to an input / output optical fiber 2c of the optical switch device 1, and an input / output optical fiber 2d of the optical switch device 1 is connected to an optical input / output optical fiber 2d. A duplexer 22 is connected. The multiplexer 21 combines the optical signals of the respective wavelengths and guides them to one input / output optical fiber 2c. The demultiplexer 22 demultiplexes a plurality of optical signals having different wavelengths propagated through one input / output optical fiber 2d for each wavelength. Further, an add multiplexer 23 is connected to the input / output optical fibers 2a and 2e of the optical switch device 1, and a drop duplexer 24 is connected to the input and output optical fibers 2b and 2f of the optical switch device 1, respectively. Each is connected.
[0047]
By providing the optical switch device 1 in this way, it is not necessary to configure an optical ADM using a large number of m × n optical switches. Thereby, miniaturization, simplification, and cost reduction of the optical ADM can be achieved.
[0048]
The present invention is not limited to the above embodiment. For example, in the above embodiment, a mirror is used as an optical component that reflects an optical signal from the lens 5, but a prism may be used instead of the mirror.
[0049]
In the above embodiment, the electrodes 15a and 15b and the electrode 16 are provided on the substrate 8 and the movable mirror 7 is driven by electrostatic force. However, the movable mirror 7 may be driven using electromagnetic force. .
[0050]
Furthermore, in the above embodiment, the plurality of input / output ports that input and output optical signals are configured by optical fibers, but the plurality of input / output ports may be configured by planar waveguides.
[0051]
Moreover, although the said embodiment uses an optical switch device for optical ADM, the optical switch device of this invention is applicable also to an optical multiplexer / demultiplexer etc. Further, the optical switch device of the present invention is not limited to the wavelength changeover switch, and can be applied as long as the input / output optical path of the input / output port is switched.
[0052]
【The invention's effect】
According to the present invention, the first driving means for driving the optical component so as to switch the input / output optical path of the input / output port, the position for reflecting the optical signal in the direction toward the input / output port, and the optical signal toward the input / output port. Since the second driving means for driving the optical component to move between the positions reflecting in the direction shifted from the direction is provided, when switching the input / output optical path of the input / output port, other input / output ports that are not to be switched are provided. The influence on the optical signal passing through the output port can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of an optical switch device according to the present invention, and is a view when the optical switch device is viewed in the y-axis and y′-axis directions.
FIG. 2 is a schematic configuration diagram showing an embodiment of an optical switch device according to the present invention, and is a diagram when the optical switch device is viewed in the x-axis direction.
3 is a plan view showing a part of the optical switch array shown in FIGS. 1 and 2. FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
5 is a plan view of the substrate shown in FIG. 3. FIG.
FIG. 6 is a cross-sectional view showing a state in which the movable mirror is tilted with respect to the annular support portion.
7 is a cross-sectional view showing a state in which a movable mirror is moved by bending a cantilever beam in FIG. 4;
8 is a configuration diagram showing an optical ADM as an example of an optical transmission system including the optical switch device shown in FIGS. 1 and 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical switch device, 2a-2f ... Input / output optical fiber (input / output port), 3 ... Array lens, 4 ... Diffraction grating (optical demultiplexing element), 5 ... Lens, 6 ... Optical switch array (switch means), 7, 7a to 7d ... movable mirror (optical component), 8 ... substrate (base), 11 ... cantilever, 12 ... annular support, 13 ... hinge, 14 ... comb tooth, 15a, 15b ... electrode (first) Electrode, first driving means), 16 ... Electrode (second electrode, second driving means), 17 ... Voltage source (first voltage source, first driving means), 18 ... Voltage source (second voltage source, second Drive means), 20... Optical ADM (optical transmission system).

Claims (6)

In an optical switch device comprising a plurality of input / output ports for inputting / outputting optical signals, and switch means for switching input / output optical paths of the input / output ports,
The switch means includes
An optical component that reflects an optical signal input from any of the plurality of input / output ports toward another input / output port; and
First driving means for driving the optical component so as to switch an input / output optical path of the input / output port;
Second drive for driving the optical component to move between a position where the optical signal is reflected in the direction toward the input / output port and a position where the optical signal is reflected in a direction shifted from the direction toward the input / output port. It possesses the means,
The optical component is provided so as to be tiltable on a cantilever beam supported by a base,
The first driving means is means for tilting the optical component with respect to the cantilever,
The optical switch device, wherein the second driving means is means for moving the optical component in a direction different from a tilting direction of the optical component . An optical demultiplexing element for demultiplexing the wavelength multiplexed optical signal input from the input / output port for each wavelength;
2. The optical switch device according to claim 1, wherein the switch means includes a plurality of the optical components corresponding to each signal light demultiplexed for each wavelength. The first driving means includes a first electrode provided on the base, and a first voltage source for supplying a voltage to the first electrode,
3. The optical switch device according to claim 1, wherein the second driving unit includes a second electrode provided on the base and a second voltage source that supplies a voltage to the second electrode. The optical switch device according to any one of claims 1 to 3 , wherein a switching time of the input / output optical path of the input / output port is 10 ms or less. Wherein when switching the input and output optical path of the input and output ports, the other optical switch device of any one of claims 1-3, characterized in that the crosstalk is less than -25dB of the input and output ports. An optical transmission system comprising the optical switch device according to any one of claims 1 to 5 .

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