JP2003177337A - Optical waveguide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact optical waveguide device which has a low dependence on a polarized wave and a stable reflectance and is applicable to an optical attenuator, an optical equalizer, an optical switch or the like. <P>SOLUTION: The device is provided with a mirror 5 which is arranged being able to be inserted into a groove 4 so that an optical path extending from the input port of an optical waveguide 1 to the output port of an optical waveguide 2 is intercepted, and has a reflectance for a prescribed wavelength band and is transparent for outside of the prescribed wavelength band, a driving circuit which variably controls the attenuation ratio of a signal light passing through the optical path by controlling the relative positions of the optical path and the mirror 5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide device, and more particularly to an optical waveguide device applicable to an optical attenuator, an optical equalizer, an optical switch and the like.

[0002]

2. Description of the Related Art In recent years, a plurality of optical signals having different wavelengths have been multiplexed in one optical fiber in response to the increase and the sophistication of transmission capacity of an optical communication network. At the transmitting end of the optical fiber, different optical signals in a plurality of wavelength bands are combined and sent, and after being transmitted through the optical fiber,
At the receiving end, the original optical signals are demultiplexed. A silica-based optical waveguide is known as a device that realizes such a multiplexing / demultiplexing function of optical signals.

In wavelength-division-multiplexed communication, there is an equalization function for making the intensities of a plurality of multiplexed optical signals equal to each other with respect to the multiplexed signal after multiplexing the optical signals or before demultiplexing. Will be needed. The equalization function is realized by, for example, an optical equalizer having a light intensity distribution in which an intensity imbalance between a plurality of optical signals caused by fiber transmission is corrected in advance. The equalization function is performed by adjusting the amount of optical attenuation in the optical attenuation function unit installed for each optical waveguide through which each optical signal passes.

[0004]

Conventionally, the optical equalizer using the Mach-Zehnder (MZ) optical interference phenomenon by the quartz optical waveguide circuit has the following problems. The optical equalizer splits one optical waveguide into two in order to variably attenuate a single light wave, and heats and changes the refractive index of each branched waveguide. At the merging portion, the phase difference between the two light waves is changed by utilizing optical interference, and the amount of attenuation is adjusted. Therefore, the optical equalizer
Since an area for forming the two waveguides is required and a heater for heating is installed, distortion due to thermal expansion is added to the propagation of the light wave in the waveguide region, and polarization dependence occurs.

On the other hand, an optical switch is known in which a mirror is installed in an optical waveguide to perform a switching operation. The surface of the mirror was vapor-deposited with a material such as chrome / gold alloy. In such a combination of a mirror and an optical waveguide, the direction of the reflected beam is deviated due to irregular reflection due to minute surface roughness on the metal surface, deterioration of reflectance due to aging of the metal surface, or distortion of the metal surface caused by internal stress of the metal. There was a problem that such things occur.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to vary the attenuation amount by controlling a multilayer film mirror, which is small and has little polarization dependence and is stable. An object is to provide an optical waveguide device having the above reflectance.

[0007]

In order to achieve such an object, the present invention according to claim 1 is such that an optical waveguide arranged on a substrate is matched with a refractive index of the optical waveguide. An optical waveguide device having a groove filled with a liquid having a refractive index, which is arranged to be insertable in the groove so as to block an optical path from an input port of the optical waveguide to an output port of the optical waveguide, Has a reflectance within the wavelength band of
A mirror that is transparent outside the predetermined wavelength band, and a drive circuit that controls the relative positional relationship between the optical path and the mirror to variably control the attenuation amount of the signal light passing through the optical path. Characterize.

According to this structure, the attenuation amount of the signal light passing through the optical path can be changed by installing the mirror in the groove provided in the optical waveguide and controlling the relative positional relationship between the groove and the mirror. .

According to a second aspect of the present invention, there is provided a first optical waveguide arranged on the substrate, a second optical waveguide arranged on the substrate so as to intersect with the first optical waveguide, Disposed at the intersection of the first optical waveguide and the second optical waveguide,
An optical waveguide device having a groove filled with a liquid having a refractive index matching that of the optical waveguide,
A mirror for selecting one of the optical path from the input port of the optical waveguide to the output port of the first optical waveguide and the optical path from the input port of the first optical waveguide to the output port of the second optical waveguide. And a drive circuit for selecting one of the optical paths by controlling a relative positional relationship between the groove and the mirror, the mirror having a reflecting surface disposed so as to be inserted into the groove. And

According to this structure, by switching the output optical waveguide between the reflective state and the transmissive state,
It can function as an optical switch.

The invention according to claim 3 is. A first set of optical waveguides, which are arranged on the substrate and are composed of m parallel optical waveguides, and n parallel optical waveguides, which are arranged on the substrate and intersect the first set of optical waveguides. A second set of optical waveguides (m and n are integers), and a first set of optical waveguides and a second set of optical waveguides, respectively
An optical waveguide device having a groove filled with a liquid having a refractive index matching the refractive index of the optical waveguide, wherein the signal light multiplexed into a single optical fiber is supplied to the optical waveguide of the first set. From the demultiplexer for demultiplexing to each of the input ports, the optical path from the input port of the optical waveguide of the first set to the output port of the optical waveguide of the first set, and the input port of the optical waveguide of the first set A mirror for selecting one of the optical paths leading to the output port of the second set of optical waveguides, the mirror having a reflecting surface arranged to be insertable into the groove, and a relative positional relationship between the groove and the mirror. A drive circuit for controlling and selecting one of the optical paths; and a multiplexer for multiplexing output light from the output port of the second set of optical waveguides into a single optical fiber. To do.

According to this structure, a plurality of mirrors are installed in the plurality of optical waveguides, and the attenuation amount of the signal light passing through each optical waveguide is changed, so that they are multiplexed in a single optical fiber. The light intensities of a plurality of light waves can be equalized.

The invention described in claim 4 is the invention according to claim 1,
In the mirror described in 2 or 3, a plurality of thin layer plates made of silicon single crystal are arranged in parallel to each other, and the thickness of the thin layer plates and the gap between the thin layer plates are viewed from the direction of the incident light beam. It is characterized in that it is an odd multiple of 1/4 wavelength of the beam.

The invention according to claim 5 is characterized in that the thin layer plate according to claim 4 is formed of a silicon single crystal plate and has a mirror surface with a plane orientation of (111).

The invention according to claim 6 is characterized in that the gap between the thin layer plates according to claim 4 or 5 is filled with a solid resin.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. The optical waveguide device according to the present invention controls the signal light passing through the optical path from the transmissive state to the reflective state or an intermediate state thereof by changing the relative positional relationship between the optical path and the mirror in the groove of the silica optical waveguide. .

(Structure of Optical Attenuation Function Section) FIG. 1 shows an optical attenuation function section of an optical waveguide device according to an embodiment of the present invention. In the optical waveguide device, a silica-based clad layer 7-1 and a core layer are laminated on a silicon (Si) substrate 6, and the core layer is subjected to etching treatment or the like to form the optical waveguide cores 1 and 2. Further, the clad layer 7-2 is deposited on the clad layer 7-1 and the optical waveguide cores 1 and 2. The light attenuation function section is composed of the groove 4 and the mirror 5. Mirror 5
However, by vertically moving the groove 4, the optical path from the optical waveguide 1 to the optical waveguide 2 is opened or blocked. The signal light passing through the optical path is transmitted or reflected by the vertical movement of the mirror 5.

Optical waveguide cores 1 and 2 and clad layers 7-1,
When the relative refractive index difference with 7-2 is set to 0.2% or less, the size of the optical waveguides 1 and 2 for keeping the light wave in the single mode is low if the length and width of the core cross section are each about 10 μm. Single mode propagation of loss is made. Since the size of such a core cross section is commensurate with the fiber diameter, a low loss connection between the optical waveguide core and the optical fiber becomes possible in the vicinity of the connection with the optical fiber.

The groove 4 can be formed by, for example, etching treatment, and can be formed by Shimokawa et al. "Research on low loss self-holding type optical matrix switch" NTT R & D Vol.44, No.
8, 1995. P.684-688, or Horino et al., "Micromechanical Optical Switch Using Planar Waveguide", The Institute of Electronics, Information and Communication Engineers
C-1, Vol. J82-C-1, No. 6, p.335-341, 1999/6.

The upper limit of the connection loss between the optical fiber and the silica optical waveguide is usually about 0.2 dB. As for the optical attenuation function section, the upper limit of the loss in the transmissive state of the groove 4 may be set to 0.2 dB. The width of the groove 4 for reducing the loss to 0.2 dB or less is represented by the effective groove width in the direction of the beam emitted from the optical path, and is about 30 μm in the optical waveguide having a relative refractive index difference of 0.2%.

Further, the reflecting surface of the mirror 5 and the optical waveguide core 1
The optical path of is not vertical. The reflection surface of the mirror 5 has an incident angle (θ> 0) which is offset by θ degrees from the normal incidence with respect to the optical path of the optical waveguide core 1. This is to suppress light returning to the optical waveguide core 1 when the optical waveguide core 1 is used as the input waveguide. The reflected light reflected by the mirror 5 is
The end face or side wall of another optical waveguide core is irradiated.

As a result, when the optical waveguide core 1 and the mirror 5 having the incident angle θ are provided, the groove 4 having an effective groove width of 30 μm is provided.
, The true groove width seen in the traveling direction of the beam emitted from the optical path is 28.2 (= 30 cos θ) μ at θ = 20 degrees.
m.

With respect to the true groove width of the groove 4 of 28.2 μm, the total thickness of the inserted mirror 5 is 25 μm at the maximum. Such a groove 4 and a mirror 5 can easily realize fine processing and mask alignment with a processing accuracy of 0.2 μm or less based on the design rule of the current LSI manufacturing process.

The function of the optical attenuation function section according to the embodiment of the present invention will be described with reference to FIG. In the reflection state in the optical attenuation function section, the mirror 5 is inserted between the core end surface of the optical waveguide core 1 and the core end surface of the optical waveguide core 2 facing the core end surface. The signal light that has entered the groove 4 from the optical waveguide core 1 is reflected by the mirror 5. The reflected light reflected by the mirror 5 is applied to the core end surface of the optical waveguide core 3.

In the reflection state, the signal light incident on the groove 4 from the optical waveguide core 1 is divided into three components. The first component is a reflection component from the mirror 5 and goes to the core end surface of the optical waveguide core 3. The second component is the transmission component of the mirror 5 and goes toward the core end face of the optical waveguide core 2. Third
The component is a light loss component attenuated while transmitting through the Si thin layer plate in the mirror 5. Almost 100% of the incident signal light is practically divided by the mirror 5 into a first component and a second component.

(Structure and Manufacturing Method of Mirror) Next, a mirror applied to the optical attenuation function section will be described. In a multilayer film in which thin films having different refractive indexes are alternately stacked, a length of ¼ of a specific wavelength is set as a unit thickness, and the thickness of the thin films is controlled by an odd multiple of the unit thickness. In this way
It has a predetermined reflectance in a predetermined wavelength band centered on a specific wavelength, and has a characteristic of being transmitted in another wavelength band.

In this embodiment, Si is used as the mirror.
A multilayer mirror made of crystals is used. FIG. 3 shows the structure of a mirror having three Si crystal thin layer plates. Mirror 5
This is a configuration in which the Si crystal thin layer plates 10a to 10c are connected to the support base 9. The Si crystal thin layer plates 10a to 10c are high refractive index layers having a multilayer film structure, and the gaps 11a and 11b are low refractive index medium layers. The thickness of the Si crystal thin layer plates 10a to 10c and the dimensions of the gaps 11a and 11b are set to be an integral multiple of ¼ wavelength with respect to the traveling direction of light.

Although the multilayer mirror shown in FIG. 3 has a five-layer structure, the number of layers is not limited as long as the high-refractive index layers and the low-refractive index layers are alternately laminated. The reflectance can be increased by increasing the number of. Since the Si crystal used as the high-refractive index layer has a large refractive index of 3 or more, if a multilayer film is formed in combination with a low-refractive index layer having a refractive index of about 1.5, a high reflectance can be obtained even with a small number of layers. , A mirror having a broadband reflection band can be constructed. Further, the Si crystal body is advantageous in that the absorption loss is smaller than that of a polycrystalline Si thin film obtained by vapor deposition or sputtering.

The Si single crystal is not completely transparent to light in the 1.3 μm wavelength band or 1.5 μm wavelength band, so-called long wavelength band, which is applied to optical fiber communication. But,
The absorption amount of light is considerably lower than the value that affects the performance of the light attenuating function section when the crystal thickness is several tens of μm or less.

For example, in the case of 1.5 μm wavelength band, Bor
on in the order of 10 ¹⁸ (/ cm ³ ).
The transmittance is 55% when a highly absorbing Si crystal of 55 mm is used. This transmittance is 5 to 15 μm of S
When converted into the absorptance of light passing through the i-crystal thin layer plate, it is about 1/100 of the incident light, that is, about 0.04 dB. The amount of absorption of light, that is, the amount of attenuation, is a value that is sufficiently lower than the connection loss between the ordinary silica-based optical waveguide circuit and the fiber, and therefore does not impair the performance of the optical attenuation function section.

The Si single crystal is stable and has a refractive index of 3.41. Since the refractive index of the Si single crystal is higher than the refractive index of 1.45 of the matching oil filled in the silica-based optical waveguide and the groove 4, a periodic multilayer of optical interference in which the Si single crystal and the matching oil are combined. Can form a structure.

The Si crystal thin layer plate uses a Si wafer having a (110) plane-oriented surface as a starting material. (110)
After forming a silicon nitride film that serves as a mask for determining the etching orientation on the surface of the plane orientation, a fan-shaped pattern is formed with photoresist. Next, for example, etching with a KOH solution is performed to form a photoresist pattern for producing a target pattern based on the determined orientation.

The photoresist pattern is determined in consideration of the number of thin layer plates, the thickness, and the arrangement interval. In particular,
The thickness and arrangement interval of the Si crystal thin layer plate are set to an odd multiple of 1/4 of the center wavelength of the light beam, and in relation to the matching oil,
The desired reflectance is obtained. Using the photoresist as a mask, the silicon nitride film is etched to obtain a pattern. Then, using the silicon nitride film pattern as a mask, if anisotropic etching is performed using a KOH solution, for example, the etching proceeds in the depth direction (110), and the (111) plane with an extremely slow etching rate is the wafer surface. Appearing at an angle of 90 degrees with respect to, the opposing mirror surfaces of the Si crystal lamina are formed. Depending on the silicon nitride film pattern, Si crystal thin layer plates having different numbers, thicknesses and arrangement intervals of Si crystal thin layer plates are obtained. In this method, since the array of semiconductor single crystal lattices appears on the surface (111), it is possible to obtain a flat surface on the order of atomic spacing, that is, an ideal mirror surface as a mirror.

For example, in the case of a metal mirror using CrAu, irregular reflection due to surface roughness of the surface, change of reflectance due to aging of material, surface distortion caused by internal stress of metal, and the like cause reflection on an ideal mirror surface. Hard to get. As described above, by using the Si single crystal, a regular lattice array is formed over the entire crystal surface, and an ideal mirror surface as a mirror can be obtained.

1.55 ±± 1.5 μm wavelength band
The wavelength of 0.03 μm is Si at an incident angle of 20 degrees from the vertical.
When incident on a thin crystal plate, the thickness corresponding to ¼ wavelength is 106.5 nm, considering the refractive index of the Si single crystal.
Becomes Assuming a quarter wavelength × 17 times, the thickness of the Si crystal becomes 1.811 μm, and the wavelength band having a predetermined reflectance corresponds to 1.811 ± 0.036 μm.

Since the pattern drawing accuracy of the electron beam exposure apparatus is about ± 0.003 μm, the center wavelength further fluctuates by about ± 0.17%. The fluctuation amount of the center wavelength is only 4% of the entire bandwidth of 0.072 μm and does not cause an error that hinders the performance of the present apparatus.

The gaps 11a, 11 of the mirror 5 shown in FIG.
Matching oil or resin is filled in b. The height of the core cross section of the optical waveguide cores 1 to 3 is about 10 μm, and the thickness of each of the cladding layers 7-1 and 7-2 is 10 μm.
It is about m. Therefore, the Si crystal thin layer plates 10a to 10c
The height from the support substrate 9 is 30 μm.

The thickness of the mirror 5 is 25 μm as described above.
m or less, and the total thickness of the Si crystal thin layer plates 10a to 10c is set to 5 to 15 μm in which loss is not a problem in practical use. When the incident angle θ of the light beam is 20 degrees, the effective thickness is
4.7 μm to 14.1 μm, and the Si crystal thin layer plate 10
It is 1.57 μm to 4.7 μm per sheet a to 10 c. Therefore, the aspect ratio of thickness and height of the Si crystal thin layer plates 10a to 10c is 1:19 to 1: 6.4. The practical upper limit on processing accuracy is said to be 1:20,
This value is sufficiently practical.

On the other hand, the total thickness of the gaps 11a and 11b sandwiched between the Si crystal thin layer plates 10a to 10c is 20.3 μm to 10.9 μm when the thickness of the mirror 5 is 25 μm.
Becomes As described above, the mechanical strength of the mirror having the Si crystal thin plate is sufficient.

When the aspect ratio of the thickness and height of the Si crystal thin layer plates 10a to 10c is set to 1:20 which is the upper limit in processing accuracy, the total thickness of the mirror 5 can be made thinner than 25 μm. . The width of each of the gaps 11a and 11b is 1.5 μm, which is 1/20 of the mirror height of 30 μm.
And the total is 3 μm at two locations. The total thickness of the Si crystal thin layer plates 10a to 10c is 4.7 to 14.1 μm.
Therefore, the total thickness of the mirror 5 is 7.7 μm to 1
It becomes 7.1 μm. At this time, since the groove width may be about 20 μm, the insertion loss of the groove 4 can be further reduced.

If the total thickness of the Si crystal thin layer plates 10a to 10c is set to 7.7 to 12.5 μm, the mirror 5 is formed.
When the thickness is 25 μm, the number of layers of the Si crystal thin layer plate can be doubled, that is, a multilayer structure of 6 sheets can be formed.

The gaps 11a, 11 between the Si crystal thin layer plates
Instead of the matching oil, b may be filled with an organic material having a refractive index equal to or different from that of the matching oil, for example, a resin such as polyimide, to be a solidified mirror 5. The strength of the mirror 5 becomes stronger. When the refractive index of the organic substance is different from the refractive index of the matching oil, the width of the gaps 11a and 11b is converted to the refractive index of the organic substance by 1
The value is an odd multiple of / 4 wavelength.

Compared with a liquid state such as a matching oil, such a solid phase resin reduces the change in refractive index with temperature, and as a result, the temperature dependence of the reflection characteristics of the mirror is reduced.

(Function of Optical Attenuation Function Section) When the groove 4 of the optical attenuation function section is in a transmissive state, there is no interference between the mirror 5 and the core end surface of the optical waveguide core 1, and the insertion loss of the groove 4 is as described above. It becomes 0.2 dB.

FIG. 4 shows the wavelength dependence of the reflectance of the mirror having three Si crystal thin layer plates. As shown in Figure 1,
The mirror 5 shown in FIG. 3 is inserted parallel to the side wall of the groove 4 filled with the matching oil and perpendicular to the optical waveguide core 1. At this time, the wavelength range is 1.52 μm to 1.58 μm
The reflectivity of the mirror 5 is 9 at 1.52 μm on the short wave side.
8.64%, 98.30% at 1.58 μm on the long wave side, and the transmittance is 1.36% to 1.7% in the same wavelength range. Therefore, the mirror 5 shown in FIG. 3 has flatness in a desired wavelength band and realizes an optical attenuation amount of 18.2 dB ± 0.4 dB.

FIG. 5 shows the wavelength dependence of the reflectance of a mirror having six Si crystal thin layer plates. With a six-layer construction,
The reflectance is 99.8% or more. The variable range of the attenuation amount is 0 to 18.2 dB in the above-mentioned three-layer structure, and extends to 0 to 27 dB in the six-layer structure.

Generally, the reflectance depends on the plane of polarization of incident light. The above-mentioned reflectance value is an average value of reflectances calculated by changing the plane of polarization of incident light in small steps. 98% reflectance
Since it is on the table, it can be seen that the polarization dependence of the reflectance is very small. As described above, the optical attenuation function section can provide the signal light passing through the optical path from the optical waveguide core 1 to the optical waveguide core 2 with an attenuation amount of about 20 dB.

In the optical waveguide device shown in FIG. 2, the switching between the reflection state and the transmission state is performed by an optical switch that switches the optical path from the optical waveguide core 1 to either the optical waveguide core 2 or the optical waveguide core 3. Realize the function.

Further, in the optical waveguide device shown in FIG. 2, the amount of reflected light can be controlled and the amount of attenuation can be made variable by making the mirror 5 a movable mirror. Therefore, it is possible to continuously adjust from 0.2 dB in the transmissive state described above to around 20 dB in the reflective state. Such a movable mirror can be realized by applying a known micromachine technology.

For example, a method of vertically moving a metal mirror mirror by a cantilever is described in M. Katayama et al "Microm.
achined 2x2 Optical Switch Array by Stress-Induced
Bending "Technical Digest Forth International Top
ical Meeting on Contemporary Photonic Technologies
(CTP 2001), p.27-28, Mc-4, Jan. 15-17, 2001. A mirror with a plurality of Si crystal thin layer plates arranged in parallel can also be used for transmission, reflection,
Any of the intermediate states can be realized.

(Example) FIG. 6 shows the structure of an optical waveguide device according to the first embodiment of the present invention. The optical waveguide device functions as an optical attenuator. The optical waveguide device attenuates the signal light from the optical path of the optical waveguide core 1 by a predetermined amount and introduces it into the optical waveguide core 2. Note that another optical waveguide core may be placed close to at least one of the optical waveguide core 1 and the optical waveguide core 2 to add a monitor function for detecting light leaking at a constant ratio.

FIG. 7 shows the configuration of an optical waveguide device according to the second embodiment of the present invention. The optical waveguide device has a configuration in which a plurality of sets of optical waveguide core 1, optical waveguide core 2 and optical waveguide core 3 are arranged in parallel with each other. The optical waveguide device multiplexes the demultiplexer that demultiplexes the signal light multiplexed in a single optical fiber into the input port of the optical waveguide core 1 and the output light from the output port of the optical waveguide core 2. By including a multiplexer, it has a function as an equalization attenuator that equalizes the optical intensities of a plurality of light waves multiplexed in a single optical fiber.

The optical waveguide core 3 can be used as a monitor waveguide that reflects the respective demultiplexed lights by the mirror 5 and monitors the intensity thereof. The mirror 5 is set at an intermediate position where a part of the demultiplexed light is reflected. Based on the intensity ratio of the reflected light and the transmitted light obtained in advance at such an intermediate position, that is, based on the branching ratio, the intensity of the transmitted light to the optical waveguide core 2 is made constant between the ports. The position of the mirror 5 can be set. As a result, the equalized output light is input to the multiplexer. Although the optical waveguide core 3 is used as the monitor waveguide, the output light of the optical waveguide core 3 may be input to the multiplexer as the optical waveguide core 2 is used as the monitor waveguide.

On the other hand, the optical waveguide device may also be used as an optical switch in which the output light is output to either the optical waveguide core 2 or the optical waveguide core 3 by setting the mirror 5 to either the transmissive state or the reflective state. Function.

The radius of curvature of the bent portion of the optical waveguide core 3 needs to be a certain value or more in order to sufficiently confine the reflected light in the waveguide. For example, in the case of an optical waveguide in which the relative refractive index difference between the core and the clad is 0.45%, the radius of curvature is 30.
It is about mm. At this time, the planar expansion required until the optical waveguide core 3 and the optical waveguide core 1 are arranged in parallel with each other is considerably large. When the optical waveguide core 3 and the optical waveguide core 1 intersect at 40 degrees, that is, when the incident angle of the mirror 5 is 20 degrees, until the optical waveguide core 3 and the optical waveguide core 1 are arranged in parallel with each other. The waveguide length of is more than 3 mm when the waveguide spacing is about 250 μm, which is the densest arrangement spacing in the plane of the fiber. Therefore, in the structure in which the waveguides do not cross each other, the area of the chip is significantly increased by introducing the bent portion.

FIG. 8 shows the configuration of an optical waveguide device according to the third embodiment of the present invention. The difference from the second embodiment is that the optical waveguide core 3 intersects with another set of optical waveguide cores 1. There is a drawback that input light and monitor light or output light is lost due to the loss at the intersection of the cores. However, as compared with the second embodiment, the optical waveguides can be arranged more densely and the chip area can be reduced. Note that the loss at the intersection is around 0.1 dB, which is sufficiently allowable depending on the application.

FIG. 9 shows the configuration of an optical waveguide device according to the fourth embodiment of the present invention. In the third embodiment,
The optical waveguide core 3 does not have a bent portion. Since the end portions of the chips connecting the optical fibers can be formed on different surfaces of the optical waveguide core 1 and the optical waveguide core 3, the optical waveguides can be densely arranged and the chip area can be reduced.

FIG. 10 shows an optical waveguide device according to the fifth embodiment of the present invention. The optical waveguide device is an optical matrix switch in which an optical waveguide core 1 and an optical waveguide core 2 and an optical waveguide core 3 form a waveguide lattice, and a mirror 5 is arranged at each lattice point. The optical matrix switch has a plurality of terminals formed of the optical waveguide core 1 as optical signal input terminals and a plurality of terminals formed of the optical waveguide core 3 as optical signal output terminals. The optical signal input from the optical signal input terminal has its reflection path selected by the mirror 5 installed at the lattice point, and is output to an arbitrary output terminal.

FIG. 11 shows an optoelectronic circuit system including an optical waveguide device according to an embodiment of the present invention. The optoelectronic circuit system receives the monitor light c from the optical waveguide core 3 of the optical waveguide device, performs photoelectric conversion, amplifies and outputs, and attenuates transmitted light from the output of the OE converter 12. And a drive circuit 13 for calculating the amount and supplying electric power for driving the mirror 5. Illustration of the matching oil in the groove and the actuator of the mirror 5 is omitted.

The monitor light input to the OE converter 12 is applied with a monitor function of detecting light leaking at a constant ratio by bringing another optical waveguide core close to at least one of the optical waveguide core 1 and the optical waveguide core 2. May be.

The drive circuit 13 uses a method in which the relationship between the position of the mirror 5 and the attenuation amount of the transmitted light of the mirror 5 is stored in advance and the mirror 5 is controlled based on the attenuation amount set from the outside. May be. In this case, the connection between the OE converter 12 and the drive circuit 13 is not necessary, and the monitor light c is used only for the original monitoring.

An OE converter for monitoring the transmitted output light b of the optical waveguide core 2 is provided, and the mirror 5 is controlled by obtaining the attenuation amount from the monitor light c and the transmitted output light b. You can also

[0063]

As described above, according to the present invention,
By controlling the relative positional relationship between the optical path and the mirror, the amount of attenuation of the signal light passing through the optical path can be varied, and it is possible to have a small size and a stable reflectance with little polarization dependence.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an optical attenuation function section of an optical waveguide device according to an embodiment of the present invention.

FIG. 2 is a top view for explaining the function of the light attenuation function section according to the embodiment of the present invention.

FIG. 3 is a sectional view showing a structure of a mirror having three Si crystal thin layer plates.

FIG. 4 is a diagram showing the wavelength dependence of the reflectance of a mirror having three Si crystal thin layer plates.

FIG. 5 is a diagram showing wavelength dependence of reflectance of a mirror having six Si crystal thin layer plates.

FIG. 6 is a configuration diagram showing an optical waveguide device according to a first embodiment of the present invention.

FIG. 7 is a configuration diagram showing an optical waveguide device according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing an optical waveguide device according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram showing an optical waveguide device according to a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram showing an optical waveguide device according to a fifth embodiment of the present invention.

FIG. 11 is a configuration diagram showing an optoelectronic circuit system including an optical waveguide device according to an embodiment of the present invention.

[Explanation of symbols]

1-3 optical waveguide core 4 grooves 5 mirror 6 Si substrate 7-1, 7-2 Clad layer 8-1, 8-2 Core end face 12 OE converter 13 Drive circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuhiko Kurumada             1-12-1 Dogenzaka, Shibuya-ku, Tokyo             Titi Electronics Co., Ltd. (72) Inventor Toshiaki Tamamura             1-12-1 Dogenzaka, Shibuya-ku, Tokyo             Titi Electronics Co., Ltd. F-term (reference) 2H041 AA15 AA16 AB13 AC01 AC06                       AZ01 AZ08                 2H047 KA04 KA12 KB01 LA14 LA18                       PA24 QA02 TA18

Claims (6)

[Claims] 1. An optical waveguide device comprising: an optical waveguide disposed on a substrate; and a groove filled with a liquid having a refractive index matching the refractive index of the optical waveguide. A mirror that is arranged so that it can be inserted into the groove so as to block the optical path leading to the output port of the optical waveguide, has a reflectance within a predetermined wavelength band, and is transparent outside the predetermined wavelength band; and the optical path. An optical waveguide device comprising: a drive circuit that controls a relative positional relationship with the mirror to variably control an attenuation amount of signal light passing through the optical path. 2. A first optical waveguide disposed on the substrate,
A second optical waveguide that is disposed on the substrate so as to intersect with the first optical waveguide, and is disposed at an intersecting position between the first optical waveguide and the second optical waveguide, and the refraction of the optical waveguide is performed. An optical waveguide device having a groove filled with a liquid having a refractive index matching the refractive index, the optical path extending from an input port of the first optical waveguide to an output port of the first optical waveguide, and the first optical waveguide. A mirror for selecting one of the optical paths from the input port of the optical waveguide to the output port of the second optical waveguide, the mirror having a reflecting surface arranged to be inserted into the groove, the groove and the mirror And a drive circuit for selecting one of the optical paths by controlling the relative positional relationship with the optical waveguide device. 3. A first set of optical waveguides, which are arranged on a substrate and are composed of m optical waveguides that are parallel to each other, and an optical waveguide that intersects the first set of optical waveguides and is disposed on the substrate, and is parallel to each other. n
A second set of optical waveguides composed of a plurality of optical waveguides (m and n are integers), and arranged at each of the intersecting positions of the first set of optical waveguides and the second set of optical waveguides. An optical waveguide device having a groove filled with a liquid having a refractive index matching the refractive index, wherein signal light multiplexed in a single optical fiber is supplied to each of the input ports of the first set of optical waveguides. Demultiplexer, an optical path from an input port of the optical waveguide of the first set to an output port of the optical waveguide of the first set, and an input port of the optical waveguide of the first set to the second set A mirror for selecting one of the optical paths leading to the output port of the optical waveguide, the mirror having a reflecting surface arranged to be insertable into the groove, and controlling the relative positional relationship between the groove and the mirror, A drive circuit for selecting one of the optical paths, and a second set of light guides. An optical waveguide device comprising: a multiplexer that multiplexes output light from an output port of the waveguide into a single optical fiber. 4. The mirror comprises a plurality of thin layer plates made of silicon single crystal arranged in parallel with each other, and a thickness of the thin layer plates and a gap between the thin layer plates are viewed from a direction of an incident light beam. The optical waveguide device according to claim 1, 2 or 3, wherein the wavelength is set to an odd multiple of ¼ wavelength of the beam. 5. The optical waveguide device according to claim 4, wherein the thin layer plate is formed of a silicon single crystal plate and has a mirror surface with a plane orientation of (111). 6. The optical waveguide device according to claim 4, wherein the gap between the thin layer plates is filled with a solid resin.