JP2000162516A - Wavelength variable filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide wavelength selectivity, to make constitution simple and to make power consumption low by providing a diaphragm type micromachine having a half mirror and arranged between opposed optical fibers so as to be opposed to them, moving the micromachine according to a signal from the outside and changing the length of a Fabry-Perot resonator constituted of the half mirror. SOLUTION: This filter is constituted of two opposed optical fibers 106 and 107, an optical waveguide substrate 101 where a tapered type optical waveguide is formed, the tapered parts 102 and 103 of the optical waveguide, a groove part 104 formed on the substrate 101 and the diaphragm type micromachine 105 arranged in the groove part 104. The micromachine 105 is constituted of a main body, the diaphragm, a spacer, an electrode and the half mirror. The length of the Fabry-Perot resonator is changed by voltage applied to the micromachine 105, so that selected wavelength is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunable filter for selecting light having a specific wavelength from input light.

[0002]

2. Description of the Related Art Conventional tunable filters include, for example,
One disclosed in Japanese Patent Application Laid-Open No. 09-068660 is known. FIG. 6 is a diagram showing a configuration of an example of a conventional tunable filter. The conventional wavelength tunable filter shown here is composed of optical fibers 1, 2, lenses 3, 4, a servo motor 5, a rotating plate 7, a dielectric multilayer optical filter 8, and a piezoelectric element 9. The fact that the transmission wavelength characteristic of the multilayer optical filter can be changed by the incident angle of light is used.

Further, as a wavelength tunable filter using a Fabry-Perot resonator provided between optical fibers, a configuration disclosed in, for example, JP-A-04-332828 is known. This is because, as shown in FIG. 7, the silicon substrate 5 having the movable portion 508 separated into a plurality of regions is provided.
01-503, optical fibers 504 to 506 are fixed and installed for each separation area in a premises extending over each of the above areas, and mirrors ( (Not shown), and a movable portion 508 for electrostatically moving one optical fiber 505 to the silicon substrate 502 is provided. As a result, an etalon resonator is formed by the two optical fibers 504 and 506 having mirrors formed on the end faces, and a voltage is applied to the electrode 507 to move the movable section 508 to thereby achieve wavelength selectivity. It is to have.

[0004]

However, in the configuration of the conventional wavelength tunable filter, for example, in the former configuration, the rotation angle is changed so that the optical filter 8 receives an external signal and obtains a desired transmission wavelength. It is necessary to use a servomotor 5 or the like for this rotating mechanism,
Since it is necessary to convert the light incident on the optical filter 8 by the lenses 3 and 4 into collimated light, many components are required. In addition, conventional tunable filters are:
Due to the complexity of the configuration, there is a problem that it must be large, and it is expensive and consumes large power.

[0005] Furthermore, since it has a rotation mechanism and a lens coupling system, it is difficult to arrange a plurality of optical fibers in a line for application to parallel optical transmission or the like, or to combine functions. is there.

On the other hand, the configuration of the latter tunable filter is as follows.
Compared with the former configuration, the number of components is smaller and suitable for miniaturization. There are many problems. Also, it cannot be said that the configuration is suitable for arraying.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a wavelength tunable filter which is small, consumes low power, and is suitable for arraying.

[0008]

In order to solve the above-mentioned problems, a tunable filter according to the present invention comprises first and second optical waveguides arranged opposite to each other, and first and second optical waveguides. A diaphragm-type micromachine disposed between both end surfaces of the main body, the diaphragm-type micromachine comprising: a main body having a first electrode;
A first semi-transmissive member disposed on the main body and having a predetermined first transmittance, and a second semi-transmissive member disposed on the diaphragm and having a predetermined second transmittance. ing. Then, a voltage is applied to the first electrode and the second electrode to deform the diaphragm and change the resonator length of the Fabry-Perot resonator composed of the first semi-transmitter and the second semi-transmitter. Thus, light of a desired wavelength is selectively transmitted from the first optical waveguide to the second optical waveguide.

In the wavelength tunable filter according to the present invention, the first and second optical waveguides are respectively a first optical fiber and a second optical fiber. Further, a first tapered optical waveguide having a tapered portion extending toward the diaphragm-type micromachine between the first optical fiber and the diaphragm-type micromachine is provided between the second optical fiber and the diaphragm-type micromachine. A second tapered optical waveguide having a tapered portion extending toward the micromachine is provided.

The wavelength tunable filter according to the present invention also includes a plurality of first optical waveguides, a plurality of second optical waveguides disposed to face the first optical waveguides, and a first and a second optical waveguides. A plurality of diaphragm-type micromachines respectively disposed between both end surfaces of the optical waveguide, wherein the diaphragm-type micromachines each include a main body having a first electrode, and a second electrode disposed opposite to the main body. A first semi-transmissive body disposed on the main body and having a predetermined first transmittance; and a second semi-transparent body disposed on the diaphragm and having a predetermined second transmittance.
A second semi-transmissive body having a transmittance of Then, a voltage is applied to the first and second electrodes to deform the diaphragm, thereby changing the resonator length of the Fabry-Perot resonator constituted by the first and second semi-transmitters. And light of a desired wavelength is selectively transmitted from the first optical waveguide to the second optical waveguide.

The wavelength tunable filter of the present invention utilizes a silicon micromachine. A Fabry-Perot resonator capable of variably controlling the length of a resonator is disposed between optical fibers. It is characterized in that a wavelength tunable filter is configured by controlling the length so that light of a specific wavelength among incident light is selectively transmitted. The Fabry-Perot resonator can be constituted by, for example, two half mirrors arranged opposite to each other between optical fibers. Further, for example, a diaphragm-type micro machine can be applied to the means for accurately and variably controlling the interval between the half mirrors by an external signal.

As described above, the wavelength tunable filter of the present invention can be realized by using a diaphragm type micromachine, but is not limited to this. It suffices if variable control can be performed while maintaining this. That is, the first and second optical waveguides disposed opposite to each other, and the first semi-transmitter having a predetermined first transmittance and disposed near the end faces of the first and second optical waveguides. Between a second semi-transmitter having a predetermined second transmittance and being arranged in parallel with the first semi-transmitter near an end face of the second optical waveguide, and the first and second semi-transmitters And an interval control unit for controlling the interval of the light emitted from the first optical waveguide by changing the resonator length of the Fabry-Perot resonator constituted by the first and second semi-transmitters. It may be configured such that light of a specific wavelength is selectively selected and coupled to the second optical waveguide.

[0013] More specifically, the interval control unit includes:
A support member is provided between the first and second semi-transmissive members and supports the first and second semi-transmissive members. The support member is a variable elastic member whose length is expanded and contracted by an external signal. What is necessary is just to comprise in this way. Then, for example, a piezoelectric element can be provided in the variable elastic body.

[0014]

Next, an embodiment of a wavelength tunable filter according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a top view showing the configuration of one embodiment of the wavelength tunable filter of the present invention. As shown in FIG. 1, two opposing optical fibers 106 and 107, an optical waveguide substrate 101 on which a tapered optical waveguide is formed, tapered portions 102 and 103 of the optical waveguide, and a groove 104 formed on the substrate 101. , And a diaphragm-type micromachine arranged in the groove 104.

The signal light emitted from the optical fiber 106 enters the tapered optical waveguide 101,
Is converted optically into a shape close to a parallel beam, and is incident on the diaphragm type micromachine 105. The signal light transmitted therethrough is incident on the tapered portion 103, and the optical fiber 1
07. The tapered optical waveguide 101 has a groove 104 formed in the center, and a waveguide having a mode field diameter substantially the same as that of the optical fiber is tapered near the groove 104, and has tapered portions 102 and 103. It has become. The signal light is emitted through the tapered optical waveguide 101 because the signal light propagates through a certain space in order to pass through the diaphragm-type micromachine. In this case, the loss due to the beam spread is reduced as much as possible, and the signal light is again incident on the optical waveguide. It is. However, if the loss due to the beam spread is ignored, the diaphragm type micromachine may be directly disposed between the two opposing optical fibers 106 and 107 without disposing the tapered optical waveguide.

In such a configuration, a variable wavelength filter can be realized by controlling the resonator length of the Fabry-Perot resonator by the diaphragm type micromachine 105.

Here, the diaphragm type micro machine will be described with reference to FIG. FIG. 2 is a diagram showing a configuration of a diaphragm type micromachine used in the first embodiment of the wavelength tunable filter of the present invention. Diaphragm type micro machine 20 used in this embodiment
0 is the main body 201, the diaphragm 202, the spacer 20
3, electrodes 204 and 205, half mirrors 206 and 207
It consists of. Note that the half mirrors 206 and 2
Reference numeral 07 denotes a semi-transmissive body, which may be composed of, for example, a semi-transmissive film composed of a dielectric multilayer film on a transparent substrate. Further, a semi-permeable membrane may be directly formed at a predetermined position of the diaphragm type micro machine.

Such a diaphragm-type micromachine is described in, for example, "Fiber-Optic Pressure SE" by Takashi Katsumata et al.
NSOR "(MOEMS 97 pp 141-146).

Since the Fabry-Perot resonator is formed by the half mirrors 206 and 207, the light transmitted through the diaphragm type micromachine is not reflected by the half mirrors 206 and 20.
7 and is emitted with wavelength selectivity. In addition, by applying a voltage to the electrodes 204 and 205,
1. Coulomb force is generated between the diaphragms 202, and the diaphragms 202 are drawn toward the main body 204,
Since the interval between the half mirrors 206 and 207 changes, the resonator length of the Fabry-Perot resonator changes.

FIG. 3 shows a diaphragm type micromachine 3.
At 00, a state is shown in which the diaphragm 302 is drawn to the main body 301. That is, the resonator length of the Fabry-Perot resonator changes according to the voltage applied to the diaphragm type micromachine 105, and the selected wavelength can be changed. The operation of such a diaphragm-type micromachine is described in, for example, Kenji Oguma et al., “Fabry-Perot type optical wavelength tunable filter using micromachine”
(1998 IEICE General Conference, C-3-17
It is described in detail in 4).

Next, a description will be given of a second embodiment of the tunable filter according to the present invention.

In the second embodiment of the present invention, similarly to the first embodiment, the half mirrors arranged so as to be parallel to each other can be variably controlled while maintaining the parallel state. There is a feature in the point.

FIG. 4 shows a second embodiment of the tunable filter of the present invention.
It is a figure showing composition of an embodiment. In the first embodiment, a diaphragm-type micromachine is used. In the present embodiment, the half mirrors 206 and 207 formed on the surfaces of the main body 201 and the transparent plate 209 maintain a state parallel to each other. The interval can be variably controlled. Specifically, the main body 201 and the transparent plate 209 are supported by a piezoelectric element 208, and a resonator is changed by applying a signal to the piezoelectric element from the outside to change the length l. Even with such a configuration, the wavelength can be selectively transmitted by changing the resonator length. Next, a third embodiment of the tunable filter of the present invention will be described. In the third embodiment, the tunable filter of the present invention described above is applied to an array device.

FIG. 5 shows a third embodiment of the wavelength tunable filter of the present invention.
It is a top view which shows the structure of 1st Embodiment. The basic configuration is
Same as the first and second embodiments, but
The present embodiment is different in that a plurality of input / output optical fibers 306 and 307 are provided and arranged in an array.

The tapered optical waveguide substrate 301 has a number of optical waveguides corresponding to the number of optical fibers 306 and 307, and tapered portions 302 and 303 are formed toward a groove 304 formed in the center of the substrate. ing. Diaphragm-type micromachines are arranged in the groove portion 304 in correspondence with the respective tapered portions 302 and 303. The transmission wavelength can be set independently by applying a signal from outside independently.

As described above, in the present invention, it is only necessary to extend the interval between the optical waveguides to the arrangement width of the micromachine 305, and the width of this micromachine is extremely small.
Even when an array-type wavelength tunable filter is configured, it is suitable for miniaturization. Although the example using the diaphragm type micromachine applied in the first embodiment has been described here, the one using the piezoelectric element or the like shown in the second embodiment can also be realized as a basic configuration. .

[0028]

Next, an embodiment of the tunable filter of the present invention will be described.

With respect to the first embodiment of the wavelength tunable filter of the present invention shown in FIGS. 1 and 2, the following results were obtained.

In this embodiment, the half-mirrors 206 and 207 of the diaphragm type
Those having a reflectance of 95% at = 1550 ± 30 nm are used. The space between the half mirrors 206 and 207 is set to 20 μm by the spacer 203.

Under these conditions, the voltage applied to the diaphragm type micromachine 105 is changed from 0V to 15V.
By changing the center wavelength of the tunable filter to 1
It has been confirmed that the wavelength can be changed from 550 nm to 1530 nm. Thereby, for example, 1550n
Wavelength multiplexed optical ADM (AddDr) using m-band wavelength band
It has been confirmed that the present invention can be applied to a case where one channel composed of signal light having an arbitrary wavelength is selected from wavelength-multiplexed signal light and received in an (Op Multiplexer) transmission system.

[0032]

As described above, the wavelength tunable filter according to the present invention has a diaphragm type micromachine having a half mirror disposed between optical fibers facing each other, and this micromachine is operated by an external signal. Fabry composed by moving half mirror
Since the wavelength selectivity is provided by changing the resonator length of the Perot resonator, the configuration is simple and suitable for low power consumption.

The width of the micromachine is small, and the optical waveguide may be formed with this width. Therefore, the micromachine is suitable for the configuration of an array type wavelength tunable filter.

[Brief description of the drawings]

FIG. 1 is a top view showing the configuration of a first embodiment of a tunable filter of the present invention.

FIG. 2 is a diagram showing a configuration of a diaphragm type micromachine used in a first embodiment of the wavelength tunable filter of the present invention.

FIG. 3 is a diagram showing an operation state of a diaphragm type micro machine used in the first embodiment of the wavelength tunable filter of the present invention.

FIG. 4 is a top view showing a configuration of a second embodiment of the tunable filter of the present invention.

FIG. 5 is a top view showing the configuration of a third embodiment of the wavelength tunable filter of the present invention.

FIG. 6 is a top view showing a configuration of an example of a conventional wavelength variable filter.

FIG. 7 is a top view showing the configuration of another example of a conventional wavelength variable filter.

[Explanation of symbols]

 Reference Signs List 101 taper type optical waveguide 102 taper part 103 taper part 104 groove part 105 diaphragm type micro machine 106 optical fiber 107 optical fiber 200 diaphragm type micro machine 201 main body 202 diaphragm 203 spacer 204 electrode 205 electrode 206 half mirror 207 half mirror 208 piezoelectric element 209 transparent plate 301 Tapered optical waveguide 302 Tapered section 303 Tapered section 304 Groove section 305 Diaphragm micromachine 306 Optical fiber 307 Optical fiber 401 Optical fiber 402 Optical fiber 403 Lens 404 Lens 405 Servo motor 406 Rotation axis 407 Rotating plate 408 Dielectric multilayer filter 409 Piezo piezoelectric Element 501 Silicon 502 Silicon 503 Silicon 504 Optical fiber 50 Optical fiber 506 optical fiber 507 electrode 508 the movable portion 509 beam

Claims (16)

[Claims] 1. A first optical waveguide and a second optical waveguide disposed to face each other, and a diaphragm type micromachine disposed between an end face of the first optical waveguide and an end face of the second optical waveguide. A diaphragm having a first electrode, a main body having a first electrode, a diaphragm having a second electrode disposed opposite to the main body, and having a predetermined first transmittance. First
And a second semi-transmitter disposed on the diaphragm and having a predetermined second transmittance, and applying a voltage to the first electrode and the second electrode. The diaphragm is deformed to change the resonator length of a Fabry-Perot resonator constituted by the first semi-transmitter and the second semi-transmitter, and selectively emits light having a desired wavelength to the second transflector. A wavelength tunable filter transmitting light from one optical waveguide to said second optical waveguide. 2. The tunable filter according to claim 1, wherein the first optical waveguide and the second optical waveguide are a first optical fiber and a second optical fiber, respectively. Variable wavelength filter. 3. The tunable filter according to claim 2, further comprising a tapered portion disposed between said first optical fiber and said diaphragm-type micromachine and extending toward said diaphragm-type micromachine. 1 tapered optical waveguide, and a second tapered optical waveguide that is disposed between the second optical fiber and the diaphragm micromachine and has a tapered portion that extends toward the diaphragm micromachine. A wavelength tunable filter, characterized in that: 4. A plurality of first optical waveguides; a plurality of second optical waveguides disposed so as to face the first optical waveguide; and an end face of the first optical waveguide and the second optical waveguide. A plurality of diaphragm-type micromachines respectively disposed between end faces of the two optical waveguides, wherein the diaphragm-type micromachines each include a main body having a first electrode, a main body having a first electrode, and a second electrode A first diaphragm disposed on the main body and having a predetermined first transmittance;
And a second semi-transmissive member disposed on the diaphragm and having a predetermined second transmittance. A voltage is applied to the first electrode and the second electrode by applying a voltage to the first electrode and the second electrode. By deforming the diaphragm to change the resonator length of the Fabry-Perot resonator formed by the first semi-transmitter and the second semi-transmitter, light of a desired wavelength is selectively transmitted to the second transflector. A wavelength tunable filter transmitting light from one optical waveguide to said second optical waveguide. 5. The tunable filter according to claim 4, wherein the first optical waveguide and the second optical waveguide are a first optical fiber and a second optical fiber, respectively. Variable wavelength filter. 6. The tunable filter according to claim 5, further comprising a tapered portion disposed between said first optical fiber and said diaphragm-type micromachine and extending toward said diaphragm-type micromachine. 1 tapered optical waveguide, and a second tapered optical waveguide that is disposed between the second optical fiber and the diaphragm micromachine and has a tapered portion that extends toward the diaphragm micromachine. A wavelength tunable filter, characterized in that: A first optical waveguide and a second optical waveguide which are arranged to face each other; 7. A first semi-transmissive member disposed near an end face of the first optical waveguide and having a predetermined first transmittance, and a first semi-transparent body near an end face of the second optical waveguide. A second semi-transmissive member arranged in parallel with the transmissive member and having a predetermined second transmittance; and an interval control for controlling an interval between the first semi-transmissive member and the second semi-transmissive member. Means for changing the resonator length of a Fabry-Perot resonator constituted by the first semi-transmissive body and the second semi-transmissive body, the light emitted from the first optical waveguide. A tunable filter, wherein light of a specific wavelength is selectively selected and coupled to the second optical waveguide. 8. The interval control means is disposed between the first semi-transmitter and the second semi-transmitter, and supports the first semi-transmitter and the second semi-transmitter. The tunable filter according to claim 7, further comprising a support, wherein the support is a variable elastic body whose length is expanded and contracted by a signal from the outside. 9. The tunable filter according to claim 8, wherein the variable expandable body is a piezoelectric element. 10. The tunable filter according to claim 7, wherein the first optical waveguide and the second optical waveguide are each a first optical fiber and a second optical waveguide. A wavelength tunable filter, being the second optical fiber. 11. The wavelength tunable filter according to claim 10, further comprising: a first light condensing means disposed between the first optical fiber and the first semi-transmitter; The wavelength tunable filter according to claim 4, further comprising a second light condensing means disposed between the second optical fiber and the second semi-transmitting member. 12. The tunable filter according to claim 11, wherein each of said first light collecting means and said second light collecting means is a lens. 13. The tunable filter according to claim 11, wherein each of the first light collecting means and the second light collecting means is an optical waveguide having a tapered portion. 14. A plurality of first optical waveguides, a plurality of second optical waveguides disposed to face each other corresponding to the first optical waveguide, and a plurality of second optical waveguides respectively corresponding to the first optical waveguide. A plurality of first semi-transmitters arranged near an end face of the first optical waveguide and having a predetermined first transmittance; and a second optical waveguide corresponding to each of the second optical waveguides. A plurality of second semi-transmitters arranged in parallel with the first semi-transmitter near the end face of the wave path and having a predetermined second transmittance; the first semi-transmitter and the second semi-transmitter; A plurality of distance control means for controlling the distance between the light transmitting member and the light transmitting member, respectively, and changing a resonator length of the Fabry-Perot resonator formed by the first semi-transmitting member and the second semi-transmitting member. Thereby, light having a specific wavelength is selectively selected from the light emitted from the first optical waveguide. Tunable filter, characterized in that for coupling to the second optical waveguide by. 15. The tunable filter according to claim 14, wherein the first optical waveguide and the second optical waveguide are a first optical fiber and a second optical fiber, respectively. Variable wavelength filter. 16. The wavelength tunable filter according to claim 15, further comprising: a first light condensing means disposed between the first optical fiber and the first semi-transmitter; 16. The tunable filter according to claim 15, further comprising a second light condensing means disposed between the second optical fiber and the second semi-transmitting member.