JP3720008B2 - Variable wavelength light source - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for easily manufacturing an external resonator type variable wavelength light source and widening the wavelength variable range.
[0002]
[Prior art]
In recent years, with the widespread use of the Internet, traffic on communication lines has been steadily increasing, and the limit of transmission capacity has become a serious problem.
[0003]
As a technique for solving this problem, a WDM system that transmits a plurality of optical signals having different wavelengths using a single optical fiber has been developed and used in an actual communication line.
[0004]
In such a WDM communication line, a light source capable of arbitrarily setting a wavelength, that is, a variable wavelength light source is indispensable, and an external resonator type variable wavelength light source called a Litman type is well known as this type of variable wavelength light source. .
[0005]
The external resonator type variable wavelength light source basically has the structure shown in FIG.
The variable wavelength light source shown in FIG. 23 converts the light emitted from the laser light source 2 fixed to the base 1 into parallel light by the collimator lens 3 and enters the diffraction grating 4 fixed to the base 1. The diffracted light emitted from the diffraction grating 4 with respect to the incident light is incident on the mirror 5 supported so as to be able to rotate around a predetermined position O on the surface obtained by extending the diffraction surface, and is reflected by the mirror 5. The reflected light is incident on the diffraction grating 4, and the diffracted light with respect to the reflected light is returned from the diffraction grating 4 to the laser light source 2 through the collimator lens 3.
[0006]
In the variable wavelength light source having this structure, only the wavelength component orthogonal to the reflection surface of the mirror 5 among the wavelength components of the light emitted from the laser light source 2 returns to the laser light source 2, and the laser light source 2 returns. The light having the specific wavelength is excited (resonated) to emit light having the specific wavelength (resonance wavelength).
[0007]
This resonance wavelength is determined by the angle of the mirror 5 with respect to the diffraction grating 4 and, as described above, by rotating the mirror 5 around a predetermined position on the extended surface of the diffraction surface of the diffraction grating 4, the angle of the mirror 5 is determined. In contrast, the resonance wavelength can be continuously varied.
[0008]
When an external resonator type variable wavelength light source having such a basic structure is actually used as a light source for a communication system, an actuator for rotating the mirror 5 is required to be small and capable of precise rotational movement. Yes.
[0009]
In order to satisfy this requirement, conventionally, as shown in FIGS. 24 to 27, a flat-plate actuator 6 is used, and a mirror 5 is fixed so as to stand vertically (Patent Document 1). reference).
[0010]
This actuator 6 is composed of two highly conductive silicon substrates 7 and 8 that are made of an insulating film (SiO 2). ₂ ) 9 is sandwiched and formed by performing an etching process on the upper substrate 8.
[0011]
A fan-shaped hole 10 is formed in the upper substrate 8, and a movable part 11 having a fan-shaped outer shape is formed inside thereof. The bottom surface of the hole 10 has the insulating film 9 removed by etching, and the surface of the lower substrate 7 leaks out.
[0012]
The movable portion 11 extends in a narrow width from the narrower arc-shaped edge of the hole 10 toward the wider arc-shaped edge, and is parallel to the lower substrate 7 and perpendicular to the length direction thereof. The two leaf spring portions 12 and 13 that can be bent upward, the wide arc plate 14 that connects the tips of the leaf spring portions 12 and 13 in an arc shape, and the narrower one of the holes 10 from the inner edge of the arc plate 14 Electrode portions 15 extending toward the arcuate edges of the electrode portions, and comb teeth 15a and 15b projecting at predetermined intervals on both sides of the electrode portions 15.
[0013]
As shown in FIGS. 26 and 27, the movable portion 11 is supported in a state of being slightly lifted from the upper surface of the lower substrate 7, and the arc plate 14 and the electrode portion 15 are formed by the leaf spring portion 12. , 13 can be turned on a plane parallel to the lower substrate 7 inside the hole 10 by the lateral deflection.
[0014]
Fixed electrodes 16 and 17 are disposed between the leaf spring portion 12 and the electrode portion 15 and between the leaf spring 13 and the electrode portion 15, respectively.
[0015]
The fixed electrodes 16 and 17 are fixed to the lower substrate 7 via the insulating layer 9 while being insulated from the upper substrate 8, and the comb teeth 15 a and 15 b of the electrode portion 15 of the movable portion 11 are fixed. In contrast, comb teeth 16a and 17a are formed so as to be engaged with each other with a gap therebetween.
[0016]
Although the actuator 6 shown in FIGS. 24 to 27 has the simplest structure, a plurality of electrode portions 15 are provided, and fixed electrodes 16 and 17 are provided for each of the electrode portions. Sometimes it is.
[0017]
In the case of the actuator 6 configured as described above, for example, as shown in FIG. 28, when a constant voltage V is applied between the upper substrate 8 and the fixed electrode 16, comb teeth 16 a of the fixed electrode 16. And the comb teeth 15a of the electrode part 15 of the movable part 11 generate an electrostatic force therebetween, and the electrode part 15 is attracted to the fixed electrode 16 side. At 28, it rotates counterclockwise and stops at a position where the suction force and the restoring force of the leaf springs 12, 13 are balanced.
[0018]
The stop position of the movable portion 11 can be arbitrarily changed within a predetermined range by changing the applied voltage V.
[0019]
Therefore, as described above, if the mirror 5 is fixed vertically on the movable portion 11 and the lower surface of the lower substrate 7 is fixed so as to contact the upper surface of the base 1, the diffraction grating The angle of the mirror 5 with respect to 4 can be varied within a predetermined range, and the wavelength of light emitted from the laser light source 2 can be varied with a small configuration.
[0020]
[Patent Document 1]
International Publication No. 01/43241 Pamphlet
[0021]
[Problems to be solved by the invention]
However, as described above, the actuator 6 that rotates the movable portion 11 on a plane parallel to the base substrates 7 and 8 is used, and the mirror 5 standing upright on the movable portion 11 is rotated to change the wavelength. In a variable wavelength light source having a variable structure, the mirror 5 must be fixed vertically and accurately on the movable portion 11 of the actuator 6, and this work becomes very complicated.
[0022]
Further, since the movable portion 11 of the actuator 6 described above has a four-point link structure with both ends of the two leaf spring portions 12 and 13 as fulcrums, strictly speaking, the center of rotation is not constant, and its variable angle The larger the is, the more the position of the center of rotation is displaced.
[0023]
For this reason, there was a problem that a large angle change could not be given and the wavelength variable range was narrow.
[0024]
An object of the present invention is to solve this problem and provide a variable wavelength light source that is small in size, easy to manufacture, and has a wide wavelength variable range.
[0025]
[Means for Solving the Problems]
In order to achieve the object, a variable wavelength light source according to claim 1 of the present invention is
Light emitted from a laser light source (23) fixed to a base (21) is incident on a diffraction grating (25) fixed to the base, and diffracted light emitted from the diffraction grating with respect to the incident light is emitted. The light is incident on the reflector (35) movable by the actuator (30), the reflected light reflected by the reflector is incident on the diffraction grating, and the diffracted light with respect to the reflected light is returned from the diffraction grating to the laser light source. In the external resonator type variable wavelength light source that varies the wavelength of the light emitted from the laser light source according to the change in the position of the reflector with respect to the diffraction grating,
The actuator is
A substrate (32) fixed to the base;
Connecting portions (33, 34) extending linearly from the edge of the substrate and having flexibility in at least the twisting direction;
It is connected to the substrate through the connecting portion so as to be substantially flush with the substrate, and due to the flexibility of the connecting portion, the substrate can be rotated around the extension line of the connecting portion at least on the one surface side. A movable plate (35) formed with a reflection surface (37) for reflecting diffracted light from the diffraction grating;
An electrode plate for applying an electrostatic force to the movable plate, which is fixed at a position that is insulated on at least one surface side of the substrate and a part thereof is opposed to the edge of the surface of the movable plate with a gap. 51-54, 56-59),
The reflecting surface of the movable plate receives the diffracted light from the diffraction grating. And the movable plate intersects an optical path between the laser light source and the diffraction grating. Fixed to the base at a position The movable plate is formed with a window (36) for allowing light reciprocating between the diffraction gratings from the laser light source to pass therethrough. It is characterized by that.
[0026]
The variable wavelength light source of claim 2 of the present invention is the variable wavelength light source of claim 1,
A part of the electrode plate has a comb-tooth structure, and an edge portion of the movable plate has a comb tooth that enters with a gap between the comb teeth of the electrode plate. It is characterized by that.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are views showing the entire structure of a variable wavelength light source 20 according to an embodiment of the present invention, and FIGS. 3 and 4 show the structure of the main part.
[0029]
As shown in FIGS. 1 and 2, the variable wavelength light source 20 includes a base 21 having a high step portion 21 a and a low step portion 21 b whose upper surfaces are parallel to each other, and a high step portion 21 a of the base 21. The laser light source 23 that is fixed and emits light parallel to the upper surface thereof, is fixed to the high step portion 21a of the base 21, and the collimator lens 24 that converts the light emitted from the laser light source 23 into parallel light and the low of the base 21 A diffraction grating 25 which is fixed in a state where it stands vertically on the stepped portion 21 b and receives parallel light emitted from the collimating lens 24 by the diffraction surface 25 a, and a position between the collimating lens 24 and the diffraction grating 25 on the base 21. And a mirror-integrated actuator 30 that stands vertically on the low step portion 21b.
[0030]
The diffraction grating 25 is fixed such that a diffraction groove (not shown) provided on the diffraction surface 25 a thereof is orthogonal to the upper surface of the lower step portion 21 b of the base 21. Although an example in which the collimating lens 24 is provided independently of the laser light source 23 is shown here, the collimating lens 24 can be omitted when a laser light source that emits parallel light is used.
[0031]
The actuator 30 reflects the diffracted light emitted from the diffraction grating 25 that has received the parallel light from the collimating lens 24 toward the diffraction grating 25, and lasers the diffracted light corresponding to the reflected light from the diffraction grating 25 through the collimating lens 24. A reflector for returning to the light source 23 and a mechanism for rotating the reflector with respect to the diffraction grating 25 are integrally formed.
[0032]
As shown in FIGS. 3 and 4, the actuator 30 includes a single-layer actuator body 31 formed by etching a thin substrate with high conductivity (for example, an SOI substrate described later), and the actuator body 31 described later. Electrode plates 51 to 54 and 56 to 59 for applying an electrostatic force to the movable plate 35.
[0033]
The actuator body 31 includes a substrate 32, connecting portions 33 and 34, and a movable plate 35.
[0034]
The substrate 32 includes an upper plate 32a and a lower plate 32b which are horizontally long rectangular parallel to each other, a substantially U-shaped left plate 32c which vertically connects the left ends of the upper plate 32a and the lower plate 32b, and an upper plate 32a and a lower plate 32b. The right plate 32d is a vertically long rectangular right plate 32d that vertically connects the right ends of the two, and the outer shape is rectangular and the inner shape is a laterally convex shape. The lower end surface of the lower plate 32b is brought into contact with the base 21. It is fixed to stand upright in the state.
[0035]
The connecting portion 33 extends from the center inner edge of the upper plate 32a of the substrate 32 to a center of the lower plate 32b by a predetermined length so as to be orthogonal to the upper plate 32a.
[0036]
The connecting portion 34 extends from the center inner edge of the lower plate 32b of the substrate 32 to a center of the upper plate 32a with a predetermined width so as to be orthogonal to the lower plate 32b.
[0037]
Here, the widths, thicknesses, and lengths of the connecting portions 33 and 34 are such that the connecting portions 33 and 34 themselves can be twisted and tilted in a predetermined angular range, and the original state with respect to the deformation within the angular range. It is set so as to generate a restoring force for returning to.
[0038]
The movable plate 35 is a flat plate having a substantially convex outer shape that is smaller than the inner shape of the substrate 32 and is connected to the inside of the substrate 32 via the connecting portions 33 and 34. , 34 torsional deformation and inclination deformation flexibility, and rotation about the extension line of the connecting portions 33, 34 (line connecting the connecting portions 33, 34 in this case) with respect to the substrate 32 and movement in the front-rear direction Is made possible. In addition, a hole 36 is formed in the center of the movable plate 35 for allowing light reciprocating between the laser light source 23 and the diffraction grating 25 to pass therethrough.
[0039]
In addition, the movable plate 35 forms a reflector for reflecting the diffracted light from the diffraction grating 25. Here, a gap is formed in at least a notch of the left plate 32 c of the substrate 32 in the movable plate 35. A reflection surface 37 that reflects the laser light with high reflectivity is formed at a predetermined position on the surface of the protrusion 35a that enters in a certain state and faces the diffraction grating 25 side.
[0040]
However, the reflection surface 37 may be formed on the entire surface of the actuator main body 31 including the substrate 32, the coupling portions 33 and 34, and the movable plate 35, and is formed only on the entire surface of the movable plate 35. Also good.
[0041]
Moreover, as the reflective surface 37, for example, the entire surface of the actuator body 31 or the surface of the movable plate 35 is mirror-finished, a metal film exhibiting a high reflectance is formed by vapor deposition, or a reflective sheet is pasted. be able to. Further, when the actuator body 31 is made of a material exhibiting a high reflectance with respect to laser light, the material surface can be used as a reflecting surface without providing a reflecting film or a reflecting sheet.
[0042]
A plurality of comb teeth 38 (in this case three) are arranged at predetermined intervals in the vertical direction at the upper left end, the upper right end, the lower left end, and the lower right end of the movable plate 35. Are formed respectively.
[0043]
Electrode plates 51 to 54 are fixed to four corners on one side of the substrate 32 with an insulating plate 55 interposed therebetween. Each of the electrode plates 51 to 54 is provided with comb teeth 51 a to 54 a formed so that the comb teeth 38 to 41 of the movable plate 35 can enter each other with a gap.
[0044]
In addition, electrode plates 56 to 59 are fixed to the four corners of the opposite surface of the substrate 32 with the insulating plate 55 interposed therebetween. Like the electrode plates 51 and 54 on the one surface side, each of the electrode plates 56 to 59 is formed so that the comb teeth 38 to 41 of the movable plate 35 can enter each other with a gap. Comb teeth 56a to 59a are respectively provided.
[0045]
In the actuator 30 configured as described above, the optical path connecting the collimating lens 24 and the diffraction grating 25 passes through the hole 36 of the movable plate 35, and the rotation center of the movable plate 35 (the line connecting the connecting portions 33 and 34). ) Is a position on a surface obtained by extending the diffraction surface 25a of the diffraction grating 25, and the reflection surface 37 on one surface side of the movable plate 35 receives the diffracted light from the diffraction grating 25 and reflects it to the diffraction grating 25 side. The lower edge of the lower plate 32b of the substrate 32 is vertically fixed in a state where it is in contact with the lower step portion 21b of the base 21.
[0046]
In this actuator 30, when a voltage is applied between the substrate 32 and each electrode plate, the comb teeth 38 to 41 of the movable plate 35 and the combs of each electrode plate that are continuous to the substrate 32 via the connecting portions 33 and 34. An electric field is generated between the teeth 51a to 54a and 56a to 59, and the movable plate 35 receives an electrostatic force in the suction direction according to the strength of the electric field (that is, the magnitude of the applied voltage), or the posture with respect to the substrate 32 or The position changes.
[0047]
For example, as shown in FIG. 5A, the voltage Va (polarity is arbitrary) is applied to the front left electrode plates 51 and 53 with reference to the potential of the substrate 32, and the back side electrode plate. When a voltage Vb lower than the voltage Va is applied to 56 and 58, the left portion of the movable plate 35 receives a forward electrostatic force corresponding to the voltage Va and a backward electrostatic force corresponding to the voltage Vb. Move forward with differential force. At the same time, if the voltage Vb is applied to the front right electrode plates 52 and 54 and the voltage Va is applied to the back electrode plates 57 and 59, the right portion of the movable plate 35 is the front corresponding to the voltage Vb. In order to receive the electrostatic force to the rear and the backward electrostatic force corresponding to the voltage Va, it moves rearward by the difference force.
[0048]
Therefore, when a voltage is applied as shown in FIG. 5A, the entire movable plate 35 is twisted in the direction in which the left side protrudes forward and the right side protrudes rearward to twist the connection portions 33, 34. , And a stop at a position where the restoring force of the connecting portions 33 and 34 against the twist and the electrostatic force due to the applied voltage are balanced. The angle of the reflecting surface 37 changes.
[0049]
For this reason, the resonator length of the external resonator changes, the wavelength of the light returning to the laser light source 23 changes, and the wavelength of the laser light emitted from the end face of the diffraction grating 25 or the laser light source 21 changes.
[0050]
In order to rotate the movable plate 35 as described above, a voltage is applied only to the front left electrode plates 51 and 53 and the rear right electrode plates 57 and 59 with reference to the potential of the substrate 32. However, if this is done, only the force in the direction in which the movable plate 35 is intended to move will work, so the movable plate 35 will vibrate transiently and it will take some time to stop at a predetermined position. However, by applying a force that suppresses the rotation of the movable plate 35 with a low voltage from the opposite side as described above, this vibration can be reduced and can be quickly stopped at a predetermined position, that is, used as a damper. Yes.
[0051]
Further, as shown in FIG. 5B, if the magnitude relationship between the voltages applied to the respective electrodes is reversed to that in FIG. 5A, the angle of the movable plate 35 is set to a predetermined angle in the direction opposite to that described above. Can be rotated.
[0052]
In the actuator 30, the entire movable plate 35 can be moved in the front-rear direction, or at least one of the four corners of the movable plate 35 can be moved in the front-rear direction.
[0053]
For example, as shown in FIG. 6A, with reference to the potential of the substrate 32, a voltage Va is applied to the front electrode plates 51 to 54, and a voltage lower than the voltage Va is applied to the back electrode plates 56 to 59. When Vb is applied, the four corners of the movable plate 35 receive an electrostatic force corresponding to the potential difference Va−Vb, and therefore the entire movable plate 35 moves forward by inclining the connecting portions 33 and 34. It stops at the position where the restoring force of the connecting portions 33 and 34 with respect to the tilt and the electrostatic force due to the potential difference are balanced, and the distance of the reflecting surface 37 to the diffraction surface of the diffraction grating 25 changes.
[0054]
Further, as shown in FIG. 6B, if the magnitude relation of the voltage applied to each electrode plate is reversed, the entire movable plate 35 moves rearward with the connecting portions 33 and 34 inclined. Then, it stops at a position where the restoring force of the connecting portions 33 and 34 against this inclination and the electrostatic force due to the potential difference are balanced, and the distance of the reflecting surface 37 to the diffraction surface of the diffraction grating 25 changes.
[0055]
The movement of the movable plate 35 in the front-rear direction can be used to correct the shift of the rotation center of the reflection surface 37.
[0056]
That is, in the above rotation operation example, when the sum of the thickness of the actuator main body 31 and the thickness of the member forming the reflection surface 37 (which may be 0) is small, the rotation center of the reflection surface 37 and the movable plate 35. The reflection surface 37 rotates about a line where a surface obtained by extending the reflection surface 37 and a surface obtained by extending the diffraction surface of the diffraction grating 25 intersect with each other. The wavelength of the emitted light changes following the angle of the rotating plate 35.
[0057]
However, when the total thickness of the movable plate 35 and the thickness of the member forming the reflective surface 37 is large, as shown in FIG. 7A, the rotation center of the movable plate 35 (that is, the connecting portion 33, 34) and the position C ′ where the surface extending the reflecting surface 37 and the surface extending the diffraction surface of the diffraction grating 25 intersect with each other do not coincide with each other, and the position C also moves depending on the angle of the movable plate 35. Resulting in.
[0058]
When such a positional shift cannot be ignored, the front and rear positions of the entire movable plate 35 may be adjusted by applying the voltage described above. Specifically, the thickness of the movable plate 35 (the thickness of the substrate 32 and the connecting portions 33 and 33 is also equal) is 2t, and the distance from the surface of the movable plate 35 to the reflective surface 37 (the thickness of the reflective material) is α ( Assuming that α = 0, the entire movable plate 35 is moved forward by t + α as shown in FIG. 7B. By this movement, the rotation center C of the movable plate 35 and the position C ′ at which the surface extending from the reflecting surface 37 and the surface extending from the diffraction surface of the diffraction grating 25 intersect can always coincide with each other.
[0059]
Further, not only the above-described positional deviation but also the positional deviation of the actuator 30 itself can be corrected.
[0060]
For example, as shown in FIG. 8, when the actuator body 31 is not completely vertical on the base 21 and is inclined by a certain angle θ, the movable plate 35 is stationary with respect to the substrate 32. Thus, the movement control necessary for variable wavelength may be performed while maintaining the state of being inclined by the angle θ and being perpendicular to the base 21.
[0061]
When the actuator 30 is actually controlled, as shown in FIG. 9, the electrode plates 51 to 51 for the desired wavelengths λ (1) to λ (n) are included in advance including the correction voltage. The optimum voltage applied to 54, 56 to 59 is examined, and the voltage data V (1,1) to V (1,8), V (2,1) to V (2,8),..., V (n , 1) to V (n, 8) are stored in the memory 60 in association with each wavelength, and the control unit 61 having received the designation of the wavelength λ (x) receives each voltage data corresponding to the wavelength λ (x). If V (x, 1) to V (x, 8) are read from the memory 60 and the voltage is applied to each of the electrode plates 51 to 54 and 56 to 59, light of wavelength λ (x) is emitted from the variable wavelength light source 20. Can be emitted.
[0062]
Next, an example of a method for manufacturing the actuator 30 will be described with reference to FIG.
[0063]
As shown in FIG. 10, first, an active layer 100a having a high conductivity and a base substrate 100b are formed as an insulating layer (SiO 2) as a substrate material. ₂ ) An SOI (Silicon On Insulator) substrate 100 bonded with 100c interposed therebetween is prepared (step 1).
[0064]
Then, among the surfaces of the active layer 100a of the SOI substrate 100, the substrate 32, the connecting portions 33 and 34, and the movable plate 35 of the active layer 100a of the SOI substrate 100 can be etched by an ICP-RIE (Inductively Coupled Plasma Reactive Ion Etching) apparatus. A mask 101 is formed on the forming portion by using a photolithography technique (step 2).
[0065]
Next, the active layer 100a not covered with the mask 101 is etched with an ICP-RIE apparatus to form the substrate 32, the connecting portions 33 and 34, and the movable plate 35 of the actuator body 31 (step 3).
[0066]
Next, the mask 101 is removed, and an insulating layer (SiO2) is formed thereon. ₂ ) 102 and a highly conductive silicon substrate 103 prepared in advance are bonded together (step 4). For this bonding, a Fusion Bonding method is used in which the two mirror-finished silicon substrates after alignment are bonded by applying a temperature of 1200 ° C.
[0067]
Next, the mask 104 is formed in the formation part of the electrode plates 51-54 and 56-59 among the surface of the base substrate 100b and the surface of the silicon substrate 103 (process 5).
[0068]
Then, the base layer 100b and the silicon substrate 103 which are not covered with the mask 104 are etched by the ICP-RIE apparatus to form the electrode plates 51 to 54 and 56 to 59 (steps 6 and 7).
[0069]
Finally, the insulating layers 100c and 102 that do not overlap the electrode plates 51 to 54 and 56 to 59 are removed by etching, whereby the actuator 30 is completed (step 8).
[0070]
Although the case where the reflective surface is formed by mirror finishing of the silicon substrate has been described here, a metal film having a high reflectance is vapor-deposited on at least the surface of the movable plate 35 after step 8 without performing mirror finishing. Then, the reflective surface 37 may be formed or a reflective sheet may be attached.
[0071]
Here, the case where the actuator 30 is manufactured using the substrates 100 and 103 with high conductivity has been described. However, when a substrate with low conductivity is used, after the steps 1 to 8 shown in FIG. 11, a metal film 105 having high conductivity is deposited on the surface of the substrate 32 and each of the electrode plates 51 to 54 and 56 to 59, so that the movable plate 35 of the substrate 32 and each of the electrode plates 51 to 51 are deposited. An electric field can be applied between 54 and 56-59. If the metal film 105 has a high reflectance, the reflecting surface 37 of the movable plate 35 can be formed at the same time.
[0072]
As described above, in the variable wavelength light source 20 of the embodiment, the movable plate 35 itself of the actuator 30 forms a reflector for reflecting the diffracted light from the diffraction grating 25. The work of vertically fixing the movable part becomes unnecessary, and the manufacturing becomes extremely easy.
[0073]
In addition, the movable plate 35 is structured to rotate by the torsional deformation of the connecting portions 33 and 34, and the position of the rotation center is constant regardless of the variable angle, so that a large angle change can be given, and the wavelength variable range. Is effective.
[0074]
In addition, the movable plate 35 of the actuator 30 is fixed at a position intersecting the optical path between the laser light source 23 and the diffraction grating 25, and light that reciprocates between the laser light source 23 and the diffraction grating 25 is passed through the movable plate 35. Therefore, even if the distance between the laser light source 23 and the diffraction grating 25 is narrowed, the actuator 30 can be fixed between them, and the entire variable wavelength light source can be made compact.
[0075]
Further, a part of the electrode plates 51 to 54 and 56 to 59 has a comb-tooth structure, and the edge portion of the movable plate 35 is a comb tooth 37 that enters with a gap between the comb teeth of the electrode plates 51 to 54 and 56 to 59. , 38 can reduce the thickness of the entire actuator 30 without narrowing the rotation range of the movable plate 35.
[0076]
Further, in the case where the electrode plates 51 to 54 and 56 to 59 that are independent on the left, right, and top, respectively, with respect to the rotation center of the movable plate 35 as in the actuator 30 described above, not only the rotation control of the movable plate 35, The movement control in the front-rear direction with respect to the left and right and up and down can be independently performed, and fine adjustment of the entire optical system including correction of the distance to the diffraction surface of the diffraction grating 25 and correction of the inclination with respect to the base 21 is possible. .
[0077]
In the above-described actuator 30, electrode plates are provided on both surfaces of the substrate 32 so as to sandwich the movable plate 35. However, like the actuator 30A shown in FIGS. In the figure, electrode plates 51 to 54 may be provided on the front side but may be on the back side.
However, in this case, the movement of the movable plate 35 in the front-rear direction with respect to the substrate 32 is limited to one of them.
[0078]
Further, the actuator 30A shown in FIGS. 12 and 13 is further simplified so that the movable plate 35 is moved only by the left and right electrode plates (for example, the left electrode plates 51 and 53). Well, this is further simplified, and an electrode plate 61 in which upper and lower electrode plates are integrated is fixed with an insulating film 62 interposed therebetween as in the actuator 30B shown in FIGS. The movable plate 35 may be rotated. However, in this case, the rotation direction of the movable plate 35 with respect to the substrate 32 is limited to one, and movement control in the front-rear direction cannot be performed, but the comb teeth 39 and 41 on the opposite side (right side) of the movable plate 35 can be omitted. .
[0079]
Further, each of the actuators 30, 30A, 30B described above uses an electrode plate having a comb-teeth structure. However, like the actuator 30C shown in FIGS. 16 and 17, electrode plates 51 ′ to 54 ′ having a rectangular outer shape are used. An electrode substrate 70, which is patterned on one side and provided with a hole 71 for allowing light to pass through in the center, is fixed to one side of the substrate 32 with a spacer 72 having the same shape as the substrate 32 of the actuator body 31, Similarly, electrode plates 73 ′ to 59 ′ having a rectangular outer shape are patterned on one surface side, and an electrode substrate 73 having a hole 74 for allowing light to pass through the central portion is used as a spacer 75 having the same shape as the substrate 32. It may be a structure that is sandwiched and fixed to the opposite side of the substrate 32. The hole 74 of the electrode substrate 73 extends from the center of the electrode substrate 73 to the vicinity of the side end in order to receive the diffracted light from the diffraction grating 25 on the reflection surface 37 provided on the protruding portion 35 of the movable plate 35. .
[0080]
In this case, the movable plate 35 can be changed in posture and position in a region sandwiched between the electrode substrates 70 and 73, and the electrode plates 51 ′ to 54 are based on the potential of the actuator body 30 as described above. By applying a voltage to ′, 56 ′ to 59 ′, an arbitrary electrostatic force can be applied to the four corners of the movable plate 35, and its posture and position can be varied to vary the wavelength.
[0081]
In this case, the thickness of the entire actuator is increased by the thickness of the spacers 72 and 75, but the structure of the movable plate 35 and the electrode plates 51 'to 54' and 56 'to 59' is simplified and easy to manufacture. Become.
[0082]
In addition, in an actuator using such a rectangular flat plate type electrode, simplification is possible as in the case of using a comb type electrode. For example, like an actuator 30D shown in FIGS. The electrode substrate 70 and the spacer 72 may be used alone, and the electrode plates 52 'and 54' (or the electrode plates 51 'and 53') of the electrode substrate 70 may be omitted, or These electrode plates may be integrated.
[0083]
Here, an example of a manufacturing method of the actuator 30D using the rectangular plate type electrode will be described with reference to FIG.
[0084]
As shown in FIG. 20, first, an active layer 200a having a high conductivity and a mirror finish is used as a substrate material, and an insulating layer (SiO 2). ₂ ) An SOI substrate 200 bonded with 200c interposed therebetween is prepared (step 1a).
[0085]
Then, the mask 201 is applied to the surface of the active layer 200a of the SOI substrate 200 where the substrate 32, the connecting portions 33 and 34 and the movable plate 35 are formed on the surface of the active layer 200a of the SOI substrate 200 so that the ICP-RIE apparatus can perform etching. A mask 202 is formed also on a portion where the spacer 72 is formed in the base substrate 200b (step 2a).
[0086]
Next, the active layer 200a not covered with the mask 201 is etched by an ICP-RIE apparatus to form the substrate 32, the connecting portions 33 and 34, and the movable plate 35 of the actuator main body 31 (step 3a).
[0087]
Then, the mask 201 is removed, and the base substrate 200b that is not covered with the mask 202 is etched to form the spacer 72 (step 4a).
Next, the mask 202 is removed, and portions of the insulating layer 200c other than the portion sandwiched between the substrate 32 and the spacer 72 are removed by etching (step 5a). In addition, when forming a reflective surface with a metal film, the process is performed at this stage.
[0088]
On the other hand, the glass substrate 300 used as the material of the electrode substrate 70 is prepared (process 1b), and the metal film 301 is vapor-deposited on the whole surface (process 2b).
[0089]
Then, in this metal film 301, a mask 302 is formed with a photoresist on the portions where the electrode plates 51 'to 54' are formed (step 3b), and a portion of the metal film 301 not covered with the mask 302 is removed by etching. Then (step 4b), the hole 71 is further formed by through etching to complete the electrode substrate 70 (step 5b).
[0090]
Finally, the actuator body 31 and the spacer 72 obtained in the step 5a are integrally formed and the electrode substrate 70 formed in the step 5b are bonded together by anodic bonding or an adhesive, The actuator 30 is completed (step 6).
[0091]
Although a manufacturing example using the SOI substrate 200 with high conductivity is shown here, it is also possible to use a substrate with low conductivity as described above.
[0092]
In that case, after Steps 1a to 5a shown in FIG. 20, as shown in FIG. 21, a metal film 203 having a high conductivity is deposited on the surface of the substrate 32 (only the lower surface side may be used) (Step 6a). ) And the electrode substrate 70 formed in step 5b are bonded together by anodic bonding or an adhesive to complete the actuator 30 (step 7). With this metal film 203, an electric field can be applied between the movable plate 35 of the substrate 32 and each of the electrode plates 51 ′ to 54 ′. Further, if a metal film having a high reflectance is used as the metal film 105 and deposited on the upper surface side of the substrate 32 as shown in FIG. 21, the reflecting surface 37 of the movable plate 35 can be formed simultaneously. .
[0093]
In each of the actuator bodies described above, the shape of the substrate 32 is rectangular and the inner shape is a laterally convex shape, the shape of the movable plate 35 is also a laterally convex shape, and the movable plate 35 has two upper and lower connecting portions 33. However, these are not intended to limit the present invention, and the shapes of the substrate and the movable plate are arbitrary, and one connecting portion may be provided.
[0094]
For example, as shown in FIG. 22A, the outer shape of the substrate 32 can be formed in a U-shaped frame shape, and the rectangular movable plate 35 can be supported by the upper and lower connecting portions 33 and 34. In this case, as the electrode plate, the electrode plate of the electrode substrate described above can be used, and the electrode plate having the above-described comb-tooth structure can be used only for the left side.
[0095]
Further, as shown in FIG. 22B, the outer shape of the substrate 32 can be formed in an upward U-shaped frame shape, and the rectangular movable plate 35 can be supported only by the lower connecting portion 34. In this case, as the electrode plate, any of the electrode plate of the electrode substrate and the electrode plate having a comb-tooth structure can be used.
[0096]
Further, as shown in FIG. 22C, the substrate 32 may be a horizontally long rectangle, and the rectangular movable plate 35 may be supported only by the lower connecting portion 34. In this case, the electrode plate of the electrode substrate described above can be used as the electrode plate.
[0097]
【The invention's effect】
As described above, in the variable wavelength light source of the present invention, in the external resonator type variable wavelength light source, as the actuator for moving the reflector for reflecting the diffracted light from the diffraction grating, the substrate and the edge of the substrate A connecting portion extending in a straight line and having flexibility in at least the torsional direction, and connected to the substrate in a substantially flush state via the connecting portion, and at least the connecting portion to the substrate due to the flexibility of the connecting portion A movable plate having a reflecting surface for reflecting the diffracted light from the diffraction grating on one surface side and being insulated on at least one surface side of the substrate. And an electrode plate for applying an electrostatic force to the movable plate, and the reflecting surface of the movable plate has a diffracted light from the diffraction grating. Fixed to the base It is.
[0098]
Since the movable plate of the actuator itself forms a reflector as described above, the work for fixing the reflector perpendicularly to the movable portion of the actuator as in the prior art becomes unnecessary, and the manufacturing becomes extremely easy.
[0099]
In addition, the movable plate is rotated by the torsional deformation of the connecting portion, and the position of the rotation center is constant regardless of the variable angle, so that a large angle change can be given, and the wavelength variable range is widened. effective.
[0100]
In addition, the movable plate of the actuator is fixed at a position that intersects the optical path between the laser light source and the diffraction grating, and a window is formed on the movable plate for passing light traveling back and forth between the laser light source and the diffraction grating. In the apparatus, the actuator can be fixed between the laser light source and the diffraction grating, and the entire variable wavelength light source can be made compact.
[0101]
In addition, a part of the electrode plate has a comb-tooth structure, and the edge of the movable plate has comb teeth that enter with a gap between the comb teeth of the electrode plate, the rotation range of the movable plate is narrowed. Therefore, the thickness of the entire actuator can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of an embodiment of the present invention.
FIG. 2 is a plan view of the embodiment.
FIG. 3 is a perspective view of a main part of the embodiment.
FIG. 4 is an exploded perspective view of a main part of the embodiment.
FIG. 5 is an operation explanatory diagram when rotating a movable plate.
FIG. 6 is an operation explanatory diagram when moving the movable plate in the front-rear direction.
FIG. 7 is a diagram for explaining a correction operation with respect to a rotation center shift;
FIG. 8 is a diagram for explaining a correction operation with respect to the tilt of the actuator;
FIG. 9 is a diagram showing a configuration of a control unit
FIG. 10 is a diagram illustrating an example of an actuator manufacturing process.
FIG. 11 is a diagram showing a modification of the manufacturing process of the actuator
FIG. 12 is a perspective view of a deformed actuator.
FIG. 13 is an exploded perspective view of a deformed actuator.
FIG. 14 is a perspective view of a deformed actuator.
FIG. 15 is an exploded perspective view of a deformed actuator.
FIG. 16 is a perspective view of an actuator using rectangular plate-type electrodes.
FIG. 17 is an exploded perspective view of an actuator using rectangular plate-type electrodes.
FIG. 18 is a perspective view of a deformed actuator.
FIG. 19 is an exploded perspective view of a deformed actuator.
FIG. 20 is a diagram showing an example of a manufacturing process of an actuator using a rectangular flat electrode.
FIG. 21 is a view showing a modification of the manufacturing process of the actuator using the rectangular flat plate type electrode.
FIG. 22 is a view showing a modified example of the actuator main body.
FIG. 23 is a basic configuration diagram of an external resonator type variable wavelength light source.
FIG. 24 is a perspective view showing a configuration example of a main part of a conventional variable wavelength light source.
FIG. 25 is a plan view of the main part of a conventional variable wavelength light source.
26 is a cross-sectional view taken along line AA in FIG.
27 is a sectional view taken along line BB in FIG.
FIG. 28 is a diagram for explaining the operation of the main part of a conventional variable wavelength light source;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Variable wavelength light source, 21 ... Base, 23 ... Laser light source, 24 ... Collimating lens, 25 ... Diffraction grating, 30, 30A-30D ... Actuator, 31 ... Actuator body, 32 ... Substrate , 33, 34... Connecting part, 35... Movable plate, 35 a... Projecting part, 36 .. hole, 37 .. reflective surface, 38 to 41 ... comb teeth, 51 to 54, 51 ′ to 54 ′, 56-59, 56'-59 '... Electrode plate, 51a-54a, 56a-59a ... Comb, 55, 60 ... Insulating film, 70, 73 ... Electrode substrate, 71, 74 ... Hole, 72 , 75 …… Spacer

Claims (2)

Light emitted from a laser light source (23) fixed to a base (21) is incident on a diffraction grating (25) fixed to the base, and diffracted light emitted from the diffraction grating with respect to the incident light is emitted. The light is incident on the reflector (35) movable by the actuator (30), the reflected light reflected by the reflector is incident on the diffraction grating, and the diffracted light with respect to the reflected light is returned from the diffraction grating to the laser light source. In the external resonator type variable wavelength light source that varies the wavelength of the light emitted from the laser light source according to the change in the position of the reflector with respect to the diffraction grating,
The actuator is
A substrate (32) fixed to the base;
Connecting portions (33, 34) extending linearly from the edge of the substrate and having flexibility in at least the twisting direction;
It is connected to the substrate through the connecting portion so as to be substantially flush with the substrate, and due to the flexibility of the connecting portion, the substrate can be rotated around the extension line of the connecting portion at least on the one surface side. A movable plate (35) formed with a reflection surface (37) for reflecting diffracted light from the diffraction grating;
An electrode plate for applying an electrostatic force to the movable plate, which is fixed at a position that is insulated on at least one surface side of the substrate and a part thereof is opposed to the edge of the surface of the movable plate with a gap. 51-54, 56-59),
The reflecting surface of the movable plate receives a diffracted light from the diffraction grating, fixed to the base and at the position you intersects the optical path between the movable plate of the diffraction grating and the laser light source, the movable plate Is a variable wavelength light source characterized in that a window (36) is formed for passing light reciprocating between the diffraction gratings from the laser light source. 2. The electrode plate according to claim 1, wherein a part of the electrode plate has a comb-tooth structure, and an edge portion of the movable plate has comb teeth that enter with a gap between the comb teeth of the electrode plate . Variable wavelength light source.

Images