JP2004191779A - Variable light attenuator and variable light attenuating device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense a high voltage, to broaden the range of movement of a shutter, to easily control attenuation, and to stably obtain desired attenuation. <P>SOLUTION: The incident end of an optical waveguide 22 is arranged with a space from the emitting end of an optical waveguide 21. An actuator 13 moves the shutter 14 to a location within the space at which the light made incident from the emitting end of the optical waveguide 21 to the incident end of the optical waveguide 22 is attenuated at the desired attenuation. The actuator 13 has beam parts 33a and 33b which form a leaf spring of which the fixed end is fixed on the substrate 31, and a connection part 34 which is connected between the beam parts 33a and 33b. The shutter 14 is provided at the connection part 34. A part of an aluminum film 38 which extends in the Y-axis direction at the connection part 34 is arranged in a magnetic field and composes an electric circuit which generates a Lorentz force to resist against a spring force of the beam parts 33a and 33b by being energized. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a variable optical attenuator whose attenuation can be controlled by an external signal, and a variable optical attenuator using the same.
[0002]
[Prior art]
Variable optical attenuators are used, for example, in optical communications and the like. There are several types of variable optical attenuators, and Patent Literature 1 below discloses a variable optical attenuator using a MEMS (Micro-Electro-Mechanical System).
[0003]
The variable optical attenuator disclosed in Patent Document 1 is shown in FIGS. FIG. 7 is a side view showing the main part, and FIG. 8 is a plan view showing the main part. In this variable optical attenuator, a MEMS device 110 is used. The MEMS device 110 has a shutter 114 that is inserted into the gap 113 between the ends 111A and 112A of the optical fibers 111 and 112 facing each other by a controlled amount. The shutter 114 is connected to the lever arm 118. The lever arm 118 is connected to a flexure portion 117 that generates a spring force. The flexure part 117 includes flexible arms 122A and 122B. The enlarged portions 125A, 125B at one ends of the flexible arms 122A, 122B are connected to the columns 120A, 120B, respectively. The other ends of the flexible arms 122A and 122B are connected to a top plate 116 as a movable electrode. Further, a bottom plate 115 as a fixed electrode is disposed on the substrate 119 so as to face the top plate 116. A reinforcing portion 123 is provided between the flexible arms 122A and 122B, and a lever arm 118 extends from the reinforcing portion 123. When the top plate 116 moves downward, the shutter 114 is moved upward by the lever arm 118 about the supporting columns 120A and 120B, and a lever structure is adopted.
[0004]
In this variable optical attenuator, when no voltage is applied between the top plate 116 and the bottom plate 115, the shutter 114 does not block the optical path between the optical fibers 111 and 112 as shown in FIG. The amount of light transmitted from the fiber 111 to the optical fiber 112 becomes maximum. On the other hand, when a voltage is applied between the top plate 116 and the bottom plate 115, the two plates 116, 115 are attracted by the electrostatic force generated between them, the top plate 116 moves downward, and the shutter 114 rises. As a result, the light enters the gap 113 between the optical fibers 111 and 112. At this time, the shutter 114 stops at a position where the electrostatic force and the spring force of the flexure portion 117 are balanced. The amount by which the optical path between the optical fibers 111 and 112 is blocked is determined according to the stop position of the shutter 114, and the amount of light transmitted from the optical fibers 111 to 112 is reduced by that amount. Then, by changing the voltage applied between the plates 116 and 115, the stop position of the shutter 114 is changed, whereby the amount of attenuation can be changed.
[0005]
As described above, in the conventional variable optical attenuator, the position of the shutter 114 is changed using the electrostatic force.
[0006]
[Patent Document 1]
US Pat. No. 6,173,105
[0007]
[Problems to be solved by the invention]
However, the conventional variable optical attenuator has a problem that a high voltage is required because the position of the shutter is moved using electrostatic force.
[0008]
In addition, as a result of the study of the present inventors, it has been found that the following problem occurs in the conventional variable optical attenuator due to the use of electrostatic force. First, since there is no linearity between the inter-electrode voltage value and the electrode interval and the range of the adjustable electrode interval is narrow, the range in which the shutter can be moved is also narrowed. Low degree of freedom in design. Second, since there is no linearity between the inter-electrode voltage value and the electrode interval, it is not easy to control the amount of attenuation. Third, there is a case where the electrodes come into contact with each other due to electric noise or mechanical vibration. In this case, both the electrodes are electrically short-circuited and the position of the shutter is stably adjusted to a desired value. The desired attenuation cannot be stably obtained because the position cannot be held.
[0009]
Here, these problems found as a result of the study of the present inventors will be described with reference to FIGS. 9 and 10.
[0010]
The present inventors modeled the conventional variable optical attenuator as shown in FIG. Then, according to the model shown in FIG. 9, when the voltage between the plates (electrodes) 115 and 116 (voltage between the electrodes) is 5 V, 10 V, 15 V, 20 V and 25 V, the interval between the plates 115 and 116 (electrode interval) The electrostatic force between the plates 115 and 116 for d1 was calculated, and the spring force of the flexure portion 117 for the electrode interval d1 was calculated. FIG. 10 shows the calculation results. Further, based on the calculation results, how the electrostatic force and the spring force are balanced (that is, where the plate 116 is located) was examined.
[0011]
In the model shown in FIG. 9, only the spring force and the electrostatic force are applied to the plate 116 in exactly opposite directions. The flexure portion 117 is an ideal spring. The plates 115 and 116 are parallel plates, and the relative dielectric constant between them is 1.
[0012]
In the above calculation, it is assumed that the plates 115 and 116 are square flat plates of 50 μm square, and the initial value of the electrode interval d1 (the electrode interval when no inter-electrode voltage is applied, and the electrode interval where the spring force becomes zero). This state corresponds to the point S in FIG. 10) is 10 μm, and the spring constant of the flexure portion 117 is 3 × 10 ^-2 (N / m).
[0013]
In addition, the notation of the numerical value on the vertical axis of FIG. 10 will be described. For example, “3.0E-07” is changed to “3.0 × 10 ⁻⁰⁷ It means "." This is the same for the notation of numerical values on the vertical axis in FIG. 6 described later.
[0014]
In FIG. 10, a solid line indicates the electrostatic force, and a broken line indicates the spring force. If the solid line is above the broken line, the electrostatic force is stronger than the spring force, and the electrodes 115 and 116 are attracted to each other, and the electrode gap d1 is reduced. For example, when the voltage between the electrodes is 25 V, the solid line is always above the broken line, so the electrode 116 starts from the position of 10 μm interval and the electrode interval becomes narrower, but the electrostatic force always exceeds the spring force. It does not stop until both electrodes 115 and 116 come into contact.
[0015]
On the other hand, when the voltage between the electrodes is 15 V, the solid line and the dashed line intersect at the time when the electrode interval is 9 μm, and when it is less than that, the spring force is greater. When the voltage between the electrodes is 20 V, the voltage is just before the solid line and the broken line intersect, and the intersection is near 7 μm. Therefore, when the electrode spacing is 7 μm or less, the electrostatic force and the spring force cannot be balanced. That is, the operating range as the electrode interval is only 10 μm to 7 μm, which is very narrow. Further, when looking at the balance points A, B, C, and D when the inter-electrode voltage is set to 5 V, 10 V, 15 V, and 20 V, it can be seen that there is no linearity between the inter-electrode voltage value and the electrode interval.
[0016]
Further, when the device is operated at about 20 V and it is tried to stop at around 7 μm, the vicinity is very unstable around 7 μm, and the balance is temporarily lost due to electric noise or mechanical vibration. Once in the left area, the electrostatic force is always greater than the spring force, and the electrodes 115 and 116 come into contact.
[0017]
The present invention has been made in view of such circumstances, and (1) a high voltage is not required, and (2) a range in which a shutter can be moved is widened, thereby increasing design flexibility. (3) The relationship between the signal and the position of the shutter becomes linear, thereby facilitating the control of the amount of attenuation, and (4) preventing the balance from being lost due to electrical noise or mechanical vibration. A variable optical attenuator and a variable light using the variable optical attenuator, which can simultaneously obtain the four advantages of being able to obtain a desired amount of attenuation stably without the risk of causing an electrical short circuit. It is an object to provide a damping device.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a variable optical attenuator according to a first aspect of the present invention includes a first optical waveguide for guiding incident light, and an incident end disposed at a distance from an output end of the first optical waveguide. The second optical waveguide, a shutter that can advance into the space, and attenuate light incident from the output end of the first optical waveguide to the input end of the second optical waveguide with a desired attenuation. An actuator that moves the shutter at a position, the actuator includes a fixed portion, and a movable portion that can move with respect to the fixed portion and that is provided so that a spring force according to the position acts. Wherein the movable section has a current path arranged in a magnetic field to generate a Lorentz force against the spring force when energized, and the shutter is provided in the movable section.
[0019]
A variable optical attenuator according to a second aspect of the present invention is the variable optical attenuator according to the first aspect, wherein the movable portion is formed of a thin film.
[0020]
A variable optical attenuator according to a third aspect of the present invention includes the variable optical attenuator according to the first or second aspect, and a magnetic field generator that generates the magnetic field.
[0021]
A variable optical attenuator according to a fourth aspect of the present invention is the variable optical attenuator according to the third aspect, further comprising a control unit for controlling at least one of the current in the current path and the magnetic field.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a variable optical attenuator according to the present invention and a variable optical attenuator using the same will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic plan view schematically showing a variable optical attenuator according to one embodiment of the present invention. In FIG. 1, a line that should be a hidden line (broken line) is also indicated by a solid line in order to clarify the positional relationship between the elements in a plan view. 2 to 4 show respective operation states, and are schematic cross-sectional views along line X1-X2 in FIG. For convenience of explanation, an X axis, a Y axis, and a Z axis that are orthogonal to each other are defined as shown in FIGS. 1 and 2. The surface of a later-described substrate 31 of the variable optical attenuator 1 is parallel to the XY plane. In the Z-axis direction, the direction of the arrow is called + Z direction or + Z side, and the opposite direction is called -Z direction or -Z side, and the same applies to the X-axis direction and Y-axis direction. The + side in the Z-axis direction may be referred to as an upper side, and the − side in the Z-axis direction may be referred to as a lower side.
[0024]
As shown in FIGS. 1 to 4, the variable optical attenuator according to the present embodiment includes a variable optical attenuator 1 and a magnet as a magnetic field generating unit that generates a magnetic field for the variable optical attenuator 1 as described later. 2 and a control unit 3 that supplies a control signal (current signal in the present embodiment) for realizing the attenuation indicated by the attenuation command signal to the variable optical attenuator 1 in response to the attenuation command signal. And
[0025]
The variable optical attenuator 1 includes a support 11 made of ceramic or the like, an optical waveguide substrate 12, an actuator 13, and a shutter 14 mounted on the actuator 13.
[0026]
The optical waveguide substrate 12 includes an optical waveguide 21 that guides incident light, an optical waveguide 22 that guides outgoing light after attenuation, and a groove 23 having, for example, a width of about 10 μm as a shutter receiving recess that receives the shutter 14. I have. As shown in FIG. 1, one end of the optical waveguide 21 (the output end of the optical waveguide 21) and one end of the optical waveguide 22 (the input end of the optical waveguide 22) are opposed to the groove 23 so as to face each other at an interval. The side that is exposed. The other end of the optical waveguide 21 (the incident end of the optical waveguide 21) is exposed on the end face of the optical waveguide substrate 12, and the other end of the optical waveguide 21 is connected to an optical fiber 15 for guiding incident light. Similarly, the other end of the optical waveguide 22 (the emission end of the optical waveguide 22) is exposed on the end face of the optical waveguide substrate 12, and the other end of the optical waveguide 22 is connected to the optical fiber 16 for guiding the emitted light.
[0027]
The actuator 13 is configured to move the shutter 14 to a position where the light incident from the output end of the optical waveguide 21 to the input end of the optical waveguide 22 is attenuated by a desired attenuation amount, and is configured as a MEMS in the present embodiment. Have been. The actuator 13 includes a substrate 31 mounted on the support base 11, legs 32a and 32b, and two band-shaped beam portions extending in parallel in the X-axis direction in plan view as viewed in the Z-axis direction. 33a and 33b, and a connecting portion 34 which is provided at the distal end (free end, end in the + X direction) of the beam portions 33a and 33b and mechanically connects between them and has a rectangular shape in plan view. In this embodiment, an insulating substrate such as a glass substrate is used as the substrate 31. For example, if an insulating film is formed over the substrate 31, a substrate of any material such as a silicon substrate may be used as the substrate 31. it can.
[0028]
The fixed end (the end in the −X direction) of the beam 33 a is a leg 32 a having a rising portion that rises from the substrate 31 via a wiring pattern 35 a (not shown in FIG. 1) made of an Al film formed on the substrate 31. Is mechanically connected to the substrate 31 via the. Similarly, the fixed end (the end in the −X direction) of the beam portion 33b has a leg having a rising portion that rises from the substrate 31 via a wiring pattern 35b (not shown) made of an Al film formed on the substrate 31. It is mechanically connected to the substrate 31 via the portion 32b. As described above, the free ends of the beams 33a and 33b are mechanically connected by the connecting portion 34, and the fixed ends of the beams 33a and 33b are mechanically connected to the substrate 31 via the legs 32a and 32b, respectively. Have been. Therefore, in the present embodiment, the beam portions 33a and 33b and the connection portion 34 as a whole constitute a movable portion having a cantilever structure. In the present embodiment, the substrate 31 forms a fixing part. Note that a protective film 36 such as a silicon oxide film is formed on regions other than the vicinity of the legs 32a and 32b in the wiring patterns 35a and 35b, and on other regions on the substrate 31.
[0029]
The beam portion 33a is a thin film in which a lower SiN film 37 and an upper Al film 38 are laminated, and is configured to function as a leaf spring. The Al film 38 in the beam 33a is used as a part of a wiring to a current path for Lorentz force described later.
[0030]
As shown in FIG. 2, the beam 33a bends upward (opposite to the substrate 31, in the + Z direction) due to the stress of the films 37 and 38 when the drive signal (the current for Lorentz force) is not supplied. ing. In FIG. 2, for convenience, the beam portion 33a is described as if it is bent at the base and extends obliquely upward in a straight line. However, actually, the beam portion 33a is entirely curved. Such a curved state can be realized by appropriately setting the film forming conditions of the films 37 and 38.
[0031]
In the present embodiment, the leg 32a is configured by the SiN film 37 and the Al film 38 constituting the beam 33a extending continuously as they are. The Al film 38 is electrically connected to the wiring pattern 35a via an opening formed in the SiN film 37 at the leg 32a.
[0032]
The beam 33b and the leg 32b have exactly the same structure as the beam 33a and the leg 32a, respectively.
[0033]
The connecting portion 34 is composed of a SiN film 37 and an Al film 38 which extend continuously from the beam portions 33a and 33b. The connection portion 34 is provided with a shutter 14 made of Au, Ni, another metal, or another material. As shown in FIG. 1, a part of the Al film 38 above the connection portion 34 extends in the Y-axis direction.
[0034]
As can be understood from the above description, the Al film 38 causes the wiring pattern 35b under the leg 32b (not shown) from the wiring pattern 35a under the leg 32a to the beam 33a → the connecting portion 34 → the beam 33b →. ) Is formed. Of these current paths, the current path along the Y-axis direction at the connection portion 34 is a portion that generates Lorentz force toward the Z-axis direction when placed in a magnetic field in the X-axis direction. Since this portion is placed in the magnetic field in the X-axis direction generated by the magnet 2 as described later, when a current (current for Lorentz force) is passed through the current path, the Al film extending in the Y-axis direction at the connection portion 34 A Lorentz force (driving force) acts on the portion 38 in the Z direction. Whether the direction of the Lorentz force is the + Z direction or the −Z direction is determined by the direction of the Lorentz force current and the direction of the magnetic field. In the present embodiment, as described above, the Lorentz force current In the state in which the Lorentz force is not supplied, as shown in FIG. 2, the direction of the Lorentz force current may be determined so that the Lorentz force is generated only in the −Z direction. However, for example, in a state where the Lorentz force current is not supplied, if the current does not curve upward or downward as shown in FIG. 3, the direction of the Lorentz force current can be changed to any direction. It is good to keep it. When the current for the Lorentz force is curved downward as shown in FIG. 4 in a state where the current for the Lorentz force is not supplied, the direction of the current for the Lorentz force is determined so that the Lorentz force is generated only in the + Z direction. Just fine.
[0035]
Although not shown in the drawings, the wiring patterns 35a and 35b can be connected to an external control unit 3 in the same manner as a normal silicon semiconductor element wiring method. A Lorentz force current is supplied as a control signal.
[0036]
The actuator 13 used in the present embodiment can be manufactured by using a semiconductor manufacturing technique such as film formation and patterning, etching, and formation / removal of a sacrificial layer. The shutter 14 may be formed, for example, by forming a recess corresponding to the shutter 14 in a resist, growing Au, Ni, or another metal to be the shutter 14 by electrolytic plating, and then removing the resist. Can be formed.
[0037]
In the present embodiment, the magnet 2 is a plate-shaped permanent magnet in which the + side in the X-axis direction is magnetized to the N pole and the − side to the S pole, as shown in FIGS. It is provided at a position on the + X side of the lower surface. Therefore, the magnet 2 has a substantially uniform magnetic field directed to the negative side along the X-axis direction near the portion of the Al film 38 (the Lorentz force current path) extending in the Y-axis direction at the connection portion 34 of the actuator 13. Has occurred. Of course, instead of the magnet 2, a permanent magnet having another shape, an electromagnet, or the like may be used as the magnetic field generator.
[0038]
As shown in FIGS. 1 to 4, the optical waveguide substrate 12 is bonded on the substrate 31 of the actuator 13 via the frame-shaped spacer 17, and is surrounded by the spacer 17 between the waveguide substrate 12 and the substrate 31. A refractive index matching liquid (not shown) is sealed in the space formed and the space in the groove 23 communicating therewith. Needless to say, the refractive index matching liquid does not necessarily have to be sealed, but when the refractive index matching liquid is used, the loss of the light beam is further reduced. The substrate 31 and the optical waveguide substrate 12 are aligned so that the shutter 14 can be inserted into the groove 23.
[0039]
FIG. 2 shows a state in which a current for Lorentz force is not supplied from the control unit 3 to the current path. In this case, the Lorentz force does not act on the portion of the Al film 38 extending in the Y-axis direction at the connection portion 34, and the shutter 14 completely blocks the emission end of the optical waveguide 21. Therefore, the attenuation is 100%.
[0040]
FIG. 3 shows a state in which a moderate Lorentz force current is supplied from the control unit 3 to the current path. In this case, since a moderate Lorentz force acts downward on the portion of the Al film 38 extending in the Y-axis direction at the connection portion 34, the shutter 14 applies the Lorentz force and the spring force of the beams 33a and 33b to each other. Stop at a position where the light beams are balanced, and block about the lower half of the emission end of the optical waveguide 21. Therefore, the attenuation is about 50%.
[0041]
FIG. 4 shows a state in which a large Lorentz force current is supplied from the control unit 3 to the current path. In this case, since a large Lorentz force acts downward on the portion of the Al film 38 extending in the Y-axis direction at the connection portion 34, the shutter 14 balances this Lorentz force with the spring force of the beam portions 33a and 33b. And stops at the outgoing end of the optical waveguide 21 at all. For this reason, the attenuation is almost 0%.
[0042]
The operation state is not limited to the examples shown in FIGS. 2 to 4, and the amount of Lorentz force is changed by changing the value of the current flowing from the control unit 3 to the current path to continuously reduce the attenuation from approximately 0% to 100%. Can be changed arbitrarily.
[0043]
In the present embodiment, the control unit 3 is configured to allow a current having a magnitude corresponding to the attenuation indicated by the attenuation command signal to flow through the current path in response to an external attenuation command signal. ing. The circuit configuration itself does not require a special one, and can be easily realized by a combination of a DC current source or a DC voltage source and a resistor. Further, the control unit 3 may perform open-loop control according to a table indicating a relationship between a current value and an attenuation amount measured in advance, or may use a detector that monitors the amount of light after attenuation, Based on the detection signal, feedback control may be performed such that the actual amount of attenuation is equal to the amount of attenuation indicated by the attenuation amount command signal.
[0044]
In this embodiment, the control unit 3 is configured to control the Lorentz force by controlling the current flowing through the current path. However, for example, an electromagnet is used as the magnet 2 and the control unit 3 May be configured to control only the magnetic field generated by the magnet 2 or to control both the current flowing through the current path and the magnetic field generated by the magnet 2.
[0045]
The present inventors modeled the variable optical attenuator 1 used in the variable optical attenuator according to the present embodiment as shown in FIG. Then, according to the model shown in FIG. 5, currents (wire currents) flowing through the straight electric wires 38 ′ (modeled portions of the Al film 38 extending in the Y-axis direction at the connection portions 34) are 10 mA, 20 mA, 30 mA, The Lorentz force acting on the electric wire 38 'with respect to the distance d2 between the electric wire 38' and the substrate 31 at the time of 40 mA and 50 mA was calculated, and the spring force of the beam portions 33a and 33b with respect to the distance d2 was calculated. FIG. 6 shows the result. Further, based on the calculation result, how the Lorentz force and the spring force are balanced (that is, where the electric wire 38 'is located) was examined.
[0046]
In the model shown in FIG. 5, only the spring force and the Lorentz force are applied to the electric wire 38 'in opposite directions. The beams 33a and 33b are ideal springs.
[0047]
In the above calculation, the length of the electric wire 38 ′ was set to 50 μm. The electric wire 38 'is in a uniform magnetic field having a magnetic flux density of 0.1 (T). Further, an initial value of the interval d2 (an interval in a state where no current flows through the electric wire 38 ', an interval at which the spring force becomes zero. This state corresponds to a point S in FIG. 5). Is set to 10 μm, and the spring constant of the beam portions 33a and 33b is set to 3 × 10 ^-2 (N / m).
[0048]
In FIG. 6, a solid line indicates the Lorentz force, and a broken line indicates the spring force. Since the Lorentz force is constant without depending on the distance d2 between the electric wire 38 'and the substrate 31, the broken line representing the spring force and the solid line representing the Lorentz force intersect at equal intervals. For example, if the current value of the electric wire 38 'is 10 mA, the electric wire 38' crosses at the point A, so that the electric wire 38 'starts from the start position S, and the spring force and the Lorentz force are balanced at the point A. The stop at the point A because the force becomes stronger than the Lorentz force, and the position is stably maintained. As the current value increases, the electric wire 38 'approaches the substrate 31. As shown in FIG. 6, the intersections A to E of the Lorentz force and the spring force for each current value are arranged at equal intervals, and it can be seen that there is linearity between the current value and the interval d2.
[0049]
When FIG. 10 is compared with FIG. 6, in the case of FIG. 10, the electric wire 38 'can be freely controlled in a wide range by changing the current value. Therefore, according to the present embodiment, the range in which the shutter 14 can be moved is widened, thereby increasing the degree of freedom in design.
[0050]
Further, as described above, since there is linearity between the current value and the interval d2, according to the present embodiment, the control of the amount of attenuation is facilitated.
[0051]
Further, from the relationship between the Lorentz force and the spring force shown in FIG. 6, even if the electric wire 38 'is located at any balance point, the electric wire 38' is stably held at the balance point unless the current is changed. . For this reason, even if the electric wire 38 'is once shifted due to electric noise or mechanical vibration, the electric wire 38' automatically returns to the balance point, and the balance is not broken. Therefore, according to the present embodiment, a desired damping force can be stably obtained. Needless to say, an electrical short as conventionally occurred cannot occur. That is, since the position of the connection portion 34 can be accurately controlled, it is extremely easy to control the connection portion 34 so as not to contact the substrate 31. If the connection portion 34 does not contact the substrate 31, an electrical short circuit may occur. Can't happen. Even if the connecting portion 34 comes into contact with the substrate 31 as shown in FIG. 4, only the Al film 38 as a wiring is arranged on the connecting portion 34, and there is no short-circuited electrode on the substrate 31 side. In addition, since the surface of the substrate 31 is insulated by the protective film 36 such as a silicon oxide film, and the Al film 38 is disposed above the SiN film 37 which is an insulating film, no electrical short circuit can occur. .
[0052]
In this embodiment, since a Lorentz force is used instead of an electrostatic force, it goes without saying that a high voltage is not required.
[0053]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this Embodiment.
[0054]
In the above-described embodiment, the actuator 13 has a cantilever structure manufactured by a surface MEMS process for manufacturing a thin film structure on a substrate. However, in the present invention, instead of the actuator 13, , An actuator manufactured by a substrate MEMS process of manufacturing a structure by etching a substrate, an actuator having a doubly supported structure, and a lever structure similar to the conventional variable optical attenuator disclosed in Patent Document 1 described above. May be used.
[0055]
【The invention's effect】
As described above, according to the present invention, (1) no high voltage is required, (2) the range in which the shutter can be moved is widened, and the degree of freedom in design is increased, and (3) The relationship between the signal and the position of the shutter becomes linear, thereby facilitating the control of the amount of attenuation. (4) The balance is not lost due to electrical noise or mechanical vibration. Provided is a variable optical attenuator and a variable optical attenuator using the variable optical attenuator, which can simultaneously obtain the four advantages that there is no possibility that an electrical short circuit occurs and that a desired amount of attenuation can be obtained stably. can do.
[Brief description of the drawings]
FIG. 1 is a schematic plan view schematically showing a variable optical attenuator according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a predetermined operation state, taken along line X1-X2 in FIG.
FIG. 3 is a schematic sectional view taken along line X1-X2 in FIG. 1, showing another operation state.
FIG. 4 is a schematic cross-sectional view taken along line X1-X2 in FIG. 1, showing still another operation state.
FIG. 5 is a diagram showing a model of the variable optical attenuator shown in FIGS. 1 to 4;
FIG. 6 is a diagram showing characteristics calculated based on the model shown in FIG. 5;
FIG. 7 is a side view showing a main part of a conventional variable optical attenuator.
FIG. 8 is a plan view showing a main part of the conventional variable optical attenuator shown in FIG.
FIG. 9 is a diagram showing a model of the conventional variable optical attenuator shown in FIGS. 7 and 8;
FIG. 10 is a diagram showing characteristics calculated based on the model shown in FIG. 9;
[Explanation of symbols]
1 Variable optical attenuator
2 magnet
3 control part
11 Support
12 Optical waveguide substrate
13 Actuator
14 Shutter
15, 16 optical fiber
17 Spacer
21,22 waveguide
23 grooves
32a, 32b leg
33a, 33b beams
34 Connection

Claims (4)

A first optical waveguide for guiding incident light;
A second optical waveguide having an incident end disposed at a distance from an output end of the first optical waveguide;
A shutter that can advance within the interval,
An actuator for moving the shutter to a position for attenuating light incident from the emission end of the first optical waveguide to the incidence end of the second optical waveguide with a desired attenuation amount;
With
The actuator has a fixed part, and a movable part that is movable with respect to the fixed part and is provided such that a spring force according to the position acts thereon,
The movable portion has a current path that is arranged in a magnetic field and generates a Lorentz force against the spring force when energized,
The variable light attenuator, wherein the shutter is provided in the movable part. The variable optical attenuator according to claim 1, wherein the movable portion is formed of a thin film. 3. A variable optical attenuator, comprising: the variable optical attenuator according to claim 1; and a magnetic field generator configured to generate the magnetic field. 4. The variable optical attenuator according to claim 3, further comprising a control unit that controls at least one of the current in the current path and the magnetic field.

Images