JP2004004342A - Optical waveguide device and method of manufacturing the same - Google Patents

Abstract

An optical waveguide device capable of efficiently controlling optical characteristics of an optical waveguide by a heating means such as a heater, and a method of manufacturing the same.
An optical circuit section having a predetermined waveguide pattern is formed on a glass substrate, and optical waveguides in the optical circuit section and optical waveguides in the optical circuit section are provided. Are provided with heaters 26, 27, 36, and 37, which are heating means used for controlling the temperature of the optical waveguide in each path. Further, with respect to the optical waveguides 21, 22, 31, 32 in the respective paths where the heaters 26, 27, 36, 37 are provided, groove portions as substrate removing portions are provided at predetermined positions on both sides of the respective optical waveguides. 41 to 45 are formed to penetrate the optical waveguide layer to a depth of 70% of the thickness of the glass substrate 10.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical waveguide device having an optical waveguide formed on a substrate by a predetermined waveguide pattern, and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, with the development and expansion of optical communication technology, in addition to optical elements such as light emitting elements and light receiving elements, and optical waveguides such as optical fibers and planar optical waveguides, optical multiplexers, optical demultiplexers, and optical attenuation The development and use of optical devices having various functions, such as devices, are being promoted.
[0003]
As one of such optical devices, an optical waveguide device using a planar waveguide type optical circuit constituted by an optical waveguide formed on a substrate by a predetermined waveguide pattern is used. Such an optical waveguide device has advantages such as integration of an optical circuit and miniaturization of the optical device, because the degree of freedom of the configuration of the waveguide pattern on the substrate is large.
[0004]
[Problems to be solved by the invention]
In an optical waveguide device using a planar waveguide type optical circuit, various optical devices are realized by changing the optical characteristics of the optical waveguide constituting the optical circuit in order to realize various functions as optical components. A functioning configuration is used. As a specific configuration for changing the optical characteristics of the optical waveguide, for example, a configuration for changing the light absorption characteristics of the optical waveguide by passing a current, or a change in the refractive index of the optical waveguide by applying heat or voltage For example, a configuration for causing the same to be used is used.
[0005]
Among these configurations, in an optical waveguide device having a configuration in which heat is applied to an optical waveguide to form a functional optical component, a heater for controlling the temperature of the optical waveguide is provided at a predetermined position of a waveguide pattern of a planar waveguide optical circuit. A heating means such as is installed. Then, the temperature of the optical waveguide is changed by the heat applied to the optical waveguide from the heater, and the optical characteristics such as the refractive index are controlled.
[0006]
In the above-described optical device that changes the refractive index of the optical waveguide, as a specific example of the configuration of the optical circuit, the optical waveguide through which light is propagated is branched into two paths, and light is propagated through each path. A configuration is used in which multiplexing is performed after the multiplexing. In the optical circuit having such a configuration, a heater is provided for each of the optical waveguides in each of the branched paths, and the refractive index of the optical waveguide is controlled in each of the paths. By using the fact that the optical path length of the optical waveguide in each path changes according to the change in the refractive index, the phase difference between the paths when the light propagated through the two paths is multiplexed is calculated. Can be controlled.
[0007]
Here, when the degree of integration in the planar waveguide type optical circuit constituting the optical waveguide device is increased in order to reduce the size of the functional optical component, the distance between the optical waveguides in adjacent paths is, for example, about several hundred μm. Become smaller. On the other hand, in the optical waveguide device having the above-described configuration for branching the optical waveguide through which light propagates, the temperature difference between the optical waveguides in adjacent paths is controlled in order to control the phase difference between the paths when the light is combined. Must be attached. However, if the distance between the optical waveguides is reduced due to the integration of the optical circuit, the power consumption of the heater required to generate a temperature difference increases, and the optical characteristics of the optical waveguide to realize the function as an optical component, such as increasing the power consumption. Control cannot be performed efficiently.
[0008]
The present invention has been made in order to solve the above problems, and an optical waveguide device capable of efficiently controlling optical characteristics of an optical waveguide by a heating means such as a heater, and a method of manufacturing the same. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve such an object, an optical waveguide device according to the present invention is formed of (1) a glass substrate made of a predetermined glass material, and (2) a waveguide pattern including a plurality of paths on the glass substrate, A core layer functioning as an optical waveguide; (3) a cladding layer formed so as to cover the glass substrate and the core layer and constituting the optical waveguide layer together with the core layer; and (4) a predetermined one of a plurality of paths of the optical waveguide. (5) a heating unit provided on the optical waveguide layer for the path and used for controlling the temperature of the optical waveguide on the predetermined path; and (5) an optical waveguide on the predetermined path provided with the heating unit. A substrate removing portion is provided at a predetermined position on at least one side of the optical waveguide, the substrate removing portion penetrating the optical waveguide layer and formed to a depth of 70% or more of the thickness of the glass substrate.
[0010]
In the above-described optical waveguide device, a glass substrate is used as a substrate for forming a planar waveguide type optical waveguide. Thereby, even when the distance between the substrate and the core layer is small, it is possible to reduce the loss generated in the light propagated through the core layer as the optical waveguide and the vicinity thereof.
[0011]
Further, a substrate removing portion is formed on a side of the optical waveguide in a path where the heating means is installed. This suppresses the diffusion of heat to other portions in the optical waveguide layer, so that it is possible to efficiently control the temperature of the optical waveguide by the heating means and thereby control the optical characteristics of the optical waveguide. Become. In addition, since the diffusion of heat is suppressed, unnecessary heating of the optical waveguide in a path other than the path subject to temperature control by the heating unit is prevented. Furthermore, by forming the substrate removal portion to a depth of 70% or more of the thickness of the glass substrate, controllability of the optical characteristics of the optical waveguide is improved, and influence on the optical waveguide in other paths is reduced. Can be realized.
[0012]
Here, the optical waveguide layer may have a configuration in which the core layer is formed directly on the glass substrate. In the present optical waveguide device, since the glass substrate is used as described above, even if the core layer is formed directly on the glass substrate and the cladding layer is formed only of the over cladding layer, light is propagated with low loss. It is possible to do. Alternatively, an under cladding layer may be provided between the glass substrate and the core layer.
[0013]
Further, the substrate removing portion is formed at predetermined positions on one side and the other side of the optical waveguide in a predetermined path, with the optical waveguide interposed therebetween. This makes it possible to effectively suppress the diffusion of heat to other portions in the optical waveguide layer in the optical waveguide on the path where the heating unit is provided.
[0014]
In such a configuration, it is preferable that an interval between the substrate removing portion provided on one side of the optical waveguide in the predetermined path and the substrate removing portion provided on the other side is not less than 70 μm and not more than 150 μm. . Thereby, the optical waveguide can be suitably configured by the core layer and the cladding layer in the path where the heating means is provided.
[0015]
Further, a predetermined heat insulating material is filled in the inside of the substrate removing section. Thereby, the effect of suppressing heat diffusion by the substrate removing portion can be improved.
[0016]
Also, a member made of a material having a higher thermal conductivity than the glass substrate is provided on the opposite side of the glass substrate to the optical waveguide layer so as to be in thermal contact with the glass substrate. . Thereby, excess heat in the optical waveguide layer and the glass substrate can be efficiently released to the outside.
[0017]
Further, the method for manufacturing an optical waveguide device according to the present invention includes: (1) a core layer having a waveguide pattern including a plurality of paths and functioning as an optical waveguide on a glass substrate made of a predetermined glass material; An optical waveguide forming step of forming a clad layer constituting the optical waveguide layer together with the core layer so as to cover the core layer; and (2) a predetermined path among a plurality of paths of the optical waveguide. A heating means setting step of setting a heating means used for controlling the temperature of the optical waveguide on the optical waveguide layer; and (3) a side of the optical waveguide with respect to the optical waveguide on a predetermined path where the heating means is installed. A substrate removing portion forming step of forming a substrate removing portion at a predetermined position on at least one side to penetrate the optical waveguide layer to a depth of 70% or more of the thickness of the glass substrate.
[0018]
According to the method for manufacturing an optical waveguide device described above, it is possible to suitably manufacture an optical waveguide device capable of efficiently controlling the temperature of the optical waveguide by the heating unit and controlling the optical characteristics of the optical waveguide by the heating unit. it can.
[0019]
In the optical waveguide forming step, the core layer may be formed directly on the glass substrate. Regarding the method of forming the substrate removing portion, it is preferable that the substrate removing portion is formed by any of processing using a dicer, etching, or laser processing in the substrate removing portion forming step.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of an optical waveguide device and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Also, the dimensional ratios in the drawings do not always match those described.
[0021]
FIG. 1 is a plan view showing the configuration of the first embodiment of the optical waveguide device according to the present invention. The optical waveguide device of the present embodiment comprises an optical circuit having a substrate and a planar waveguide type optical waveguide formed on the substrate, and changes the optical characteristics of the optical waveguide forming the optical circuit from heating means. It is configured as a functional optical component that is changed by heat.
[0022]
The optical waveguide device shown in FIG. 1 includes a planar waveguide type optical circuit 1 having a substrate 10 and an optical waveguide formed on the substrate 10 by a predetermined waveguide pattern. As the substrate 10, a glass substrate made of a predetermined glass material is used. As a specific glass material, for example, quartz glass or general multi-component glass is used.
[0023]
In the present embodiment, the optical waveguide on the glass substrate 10 is formed by a waveguide pattern composed of a two-channel optical circuit unit of the first optical circuit unit 2 and the second optical circuit unit 3. Further, each of the optical circuit units 2 and 3 is connected to the input end face 11 of the planar waveguide type optical circuit 1 by a waveguide pattern including a plurality of paths along a predetermined optical transmission direction (the direction of the arrow in FIG. 1). And the output end face 12.
[0024]
The first optical circuit unit 2 includes an input optical waveguide 20 provided on the input end face 11 and having an input end as one end, and an output optical waveguide 23 provided on the output end face 12 and having an output end as one end. And Further, between the optical waveguide 20 and the optical waveguide 23, there are provided two optical waveguides 21 and 22 that branch the optical waveguide 20 into two paths and merge with the optical waveguide 23.
[0025]
In the optical circuit section 2, heaters 26 and 27 are provided for the optical waveguide 21 on one path branched from the optical waveguide 20 and the optical waveguide 22 on the other path, respectively. These heaters 26 and 27 are heating means used for controlling the temperature of the optical waveguides 21 and 22 in each path.
[0026]
Similarly, the second optical circuit unit 3 includes an input optical waveguide 30 having an input terminal provided on the input end face 11 as one end, and an output optical waveguide 30 having an output end provided on the output end face 12 as one end. And an optical waveguide 33. Further, between the optical waveguide 30 and the optical waveguide 33, two optical waveguides 31 and 32 that branch the optical waveguide 30 into two paths and merge with the optical waveguide 33 are provided.
[0027]
Further, in the optical circuit section 3, heaters 36 and 37 are provided for the optical waveguide 31 on one path branched from the optical waveguide 30 and the optical waveguide 32 on the other path, respectively. These heaters 36 and 37 are heating means used for controlling the temperature of the optical waveguides 31 and 32 in each path.
[0028]
Also, the grooves 41 to 45 are provided at predetermined positions on one side and the other side of the optical waveguides 21, 22, 31, and 32 in the respective paths where the heaters 26, 27, 36, and 37 are installed. Is formed.
[0029]
FIG. 2 is a cross-sectional view of the optical waveguide device shown in FIG. 1 taken along the line II along the direction perpendicular to the light transmission direction in the optical circuit 1. The planar waveguide type optical circuit 1 includes a glass substrate 10 having a waveguide pattern including the optical waveguides 20 to 23 of the first optical circuit section 2 and the optical waveguides 30 to 33 of the second optical circuit section 3 shown in FIG. It has an optical waveguide layer formed thereon.
[0030]
On the glass substrate 10, a core layer 15 functioning as an optical waveguide is formed by a predetermined waveguide pattern. In the present embodiment, the core layer 15 is formed directly on the glass substrate 10 without through the under cladding layer. Each of the core layers 15 corresponding to the optical waveguides 20 to 23 and 30 to 33 has a substantially rectangular cross-sectional shape as shown in FIG.
[0031]
Further, an over cladding layer 16 is formed so as to cover the glass substrate 10 and the core layer 15 on the glass substrate 10. The core layer 15 and the over cladding layer 16 constitute an optical waveguide layer on the glass substrate 10. The cladding layer 16 has a lower refractive index than the core layer 15, so that the core layer 15 functions as an optical waveguide through which light propagates.
[0032]
In addition, heat is applied to the optical waveguides 21 and 22 in the two paths of the first optical circuit unit 2 and the optical waveguides 31 and 32 in the two paths of the second optical circuit unit 3. Is provided as a heating means.
[0033]
That is, the planar heater 26 is provided on the cladding layer 16 of the optical waveguide layer facing the core layer 15 corresponding to the optical waveguide 21. A heater 27 is provided on the optical waveguide layer facing the core layer 15 of the optical waveguide 22. A heater 36 is provided on the optical waveguide layer facing the core layer 15 of the optical waveguide 31. In addition, a heater 37 is provided on the optical waveguide layer facing the core layer 15 of the optical waveguide 32.
[0034]
Further, for each of the optical waveguides 21, 22, 31, 32 of the optical circuit sections 2, 3 on which the above-mentioned heaters 26, 27, 36, 37 are installed, a substrate removing section is provided at a predetermined position on both sides of the optical waveguides. Are formed.
[0035]
That is, the groove 41 is provided at a predetermined position between the end face of the glass substrate 10 on the first optical circuit section 2 side and the optical waveguide 21 and the heater 26. Further, a groove 42 is provided at a predetermined position between the optical waveguide 21 and the heater 26 and between the optical waveguide 22 and the heater 27. A groove 43 is provided at a predetermined position between the optical waveguide 22 and the heater 27 and between the optical waveguide 31 and the heater 36. A groove 44 is provided at a predetermined position between the optical waveguide 31 and the heater 36 and between the optical waveguide 32 and the heater 37. Further, a groove 45 is provided at a predetermined position between the optical waveguide 32 and the heater 37 and the end surface of the glass substrate 10 on the second optical circuit section 3 side.
[0036]
Each of these grooves 41 to 45 penetrates the cladding layer 16 of the optical waveguide layer, removes the glass substrate 10 to a depth d2, and combines the removed portion of the optical waveguide layer and the removed portion of the glass substrate 10 together. As far as the depth d1. The depth d1 of the grooves 41 to 45 is set such that the depth d2 of the removed portion of the glass substrate 10 is 70% or more of the thickness d0 of the glass substrate 10 (d2 ≧ d0 × 0.7). Have been.
[0037]
In the above configuration, light input from the input end face 11 side to the optical waveguide 20 to the first optical circuit section 2 of the planar waveguide type optical circuit 1 is transmitted to the optical waveguide 21 and the optical waveguide 22 in two paths. Is branched.
[0038]
In the optical waveguide 21, the temperature of the optical waveguide 21 is controlled using the heater 26, and the refractive index, which is the optical characteristic, is maintained or changed. Thereby, the effective optical path length of the optical waveguide 21 is controlled so as to be a desired optical path length. Similarly, in the optical waveguide 22, the temperature of the optical waveguide 22 is controlled using the heater 27, and the refractive index, which is an optical characteristic, is held or changed. Thereby, the effective optical path length of the optical waveguide 22 is controlled so as to be a desired optical path length.
[0039]
The light propagated through each of the optical waveguides 21 and 22 whose optical path lengths are controlled is multiplexed into the optical waveguide 23. At this time, the phase difference between the paths for combining the light from the optical waveguides 21 and 22 in the two paths is set according to the respective optical path lengths controlled by the heaters 26 and 27. Thereby, in the optical waveguide device shown in FIG. 1, the attenuation rate of the light output from the optical waveguide 23 to the outside from the light input to the optical waveguide 20 is controlled. The operation of the second optical circuit unit 3 is the same as that of the first optical circuit unit 2.
[0040]
The effect of the optical waveguide device according to the present embodiment will be described.
[0041]
In the optical waveguide device shown in FIGS. 1 and 2, a glass substrate 10 is used as a substrate for forming an optical waveguide in the planar waveguide optical circuit 1. Here, in the glass substrate 10, even if a part of the light propagated in the optical waveguide layer formed on the glass substrate 10 propagates in the substrate near the optical waveguide, the light is generated. Loss is small. Therefore, even in a configuration in which the distance between the glass substrate 10 and the core layer 15 corresponding to the optical waveguide is small, it is possible to reduce the loss generated in the light propagated through the core layer 15 and the vicinity thereof.
[0042]
For example, in the above-described optical waveguide device, as shown in FIG. 2, a configuration in which the core layer 15 is directly formed on the glass substrate 10 is used. As described above, even in a configuration in which the core layer 15 is formed directly on the substrate 10 and the cladding layer is formed only of the over cladding layer 16, light is transmitted with low loss by using a glass substrate as the substrate 10 as described above. be able to.
[0043]
In addition, grooves 41 to 45, which are substrate removing portions, are formed on the sides of the optical waveguides 21, 22, 31, and 32 in the path where the heaters 26, 27, 36, and 37, which are heating means, are installed. are doing. Thereby, when the corresponding optical waveguide is heated by the heater, diffusion of heat to other portions in the optical waveguide layer is suppressed. Therefore, it is possible to efficiently control the temperature of the optical waveguide by the heater and thereby control the optical characteristics such as the refractive index of the optical waveguide. Further, by suppressing the diffusion of heat, unnecessary heating of the optical waveguide in a path other than the path subject to temperature control by the heater is prevented.
[0044]
That is, for example, when attention is paid to the optical waveguide 22 of the first optical circuit unit 2 in FIG. It can be efficiently supplied to the core layer 15 corresponding to the wave path 22. Thereby, power consumption in the heater 27 for controlling the temperature of the optical waveguide 22 is reduced.
[0045]
As for the relationship with the adjacent optical waveguide, the groove 42 provided on the left side of the optical waveguide 22 prevents the heat from the heater 27 from diffusing into the adjacent optical waveguide 21. Further, the groove 43 provided on the right side of the optical waveguide 22 prevents the heat from the heater 27 from diffusing to the adjacent optical waveguide 31. This makes it possible to efficiently control the temperature of each of the optical waveguides 21, 22, 31, and 32 in the four paths adjacent to each other, and thereby control the optical characteristics of the optical waveguide.
[0046]
In addition, suppression of the influence on the adjacent optical waveguide is also useful for reducing the power consumption of the entire optical waveguide device.
[0047]
That is, in the first optical circuit section 2 having the optical waveguides 21 and 22 in two paths, when the temperature of the optical waveguide 21 is set to be higher than the optical waveguide 22 by 10 ° C., in a normal configuration in which no groove is provided. It is necessary to heat the heater 26 corresponding to the optical waveguide 21 to about 50 ° C. to 90 ° C. This is because the temperature of the adjacent optical waveguide 22 together with the optical waveguide 21 increases by heating using the heater 26. Further, in an optical waveguide device in which such an optical circuit section is integrated in a plurality of channels, the power consumption of the heater increases, and the temperature of the optical waveguide device becomes high during operation, for example, the temperature becomes 200 ° C. or more in 8 channels. There is a problem that becomes.
[0048]
As described above, when the temperature of the optical waveguide device becomes excessively high, it is necessary to provide a cooling unit for forcibly cooling the device. However, when the forced cooling means is provided in this way, although the temperature of the optical waveguide device itself is reduced, the power consumption of the optical communication system including the cooling means as a whole increases, and heat generated from the cooling means is reduced. The total amount of heat generated also increases.
[0049]
On the other hand, as described above, according to the optical waveguide device having the configuration in which the substrate removal portion is formed on the side of the optical waveguide on which the heater is installed, when the optical waveguide 21 is heated using the heater 26, In addition, an increase in the temperature of the adjacent optical waveguide 22 is suppressed. Thus, at a relatively low heating temperature, a desired temperature difference between the adjacent optical waveguides 21 and 22 can be obtained. Therefore, it is possible to reduce power consumption and heat generation of the optical waveguide device or the entire optical communication system including the optical waveguide device. Further, the configuration of the optical waveguide device can be simplified, for example, the installation of the forced cooling means to the optical waveguide device becomes unnecessary, and the device can be downsized.
[0050]
Further, in the configuration using the glass substrate 10 as the substrate for forming the planar waveguide type optical waveguide, light can be propagated in the core layer 15 and the vicinity thereof with low loss as described above. In some cases, compared to other substrates (eg, a silicon substrate), the substrate may be more susceptible to heat from adjacent channels. On the other hand, in the above-described optical waveguide device, the groove portions 41 to 45, which are the substrate removal portions, are formed to a depth of 70% or more of the thickness of the glass substrate 10. As described above, by forming the substrate removal portion between the optical waveguides at a sufficient depth, the controllability of the optical characteristics of the optical waveguide is improved, and the influence on the optical waveguide in other paths is reduced. Can be realized.
[0051]
As a conventional optical waveguide device having a configuration in which a heat is applied to an optical waveguide to form a functional optical component, for example, JP-A-5-34525 (Document 1) and JP-A-9-212240 (Document 2) , 2001, there is a device described in IEICE General Conference C-3-61 (Document 3).
[0052]
Among them, in the optical waveguide device described in Document 1, the substrate portion below the optical waveguide provided with the heater is removed from the back surface side. However, it is difficult to remove a part of the silicon substrate below the optical waveguide layer by machining or the like. In addition, in this configuration, high processing accuracy is required to remove the substrate portion immediately below the optical waveguide, so that productivity cannot be increased. Further, in the optical waveguide device described in Document 2, a composite substrate in which a silicon substrate is partially replaced with a quartz substrate is used. However, even in such a configuration, the number of steps for manufacturing the composite substrate is large. In addition, the productivity is low and the cost of the device is high.
[0053]
Further, in the optical waveguide device described in Document 3, although the heat insulating groove is provided in the optical waveguide layer formed on the silicon substrate, only the optical waveguide layer is removed to form the groove. The effect of suppressing diffusion cannot be sufficiently obtained. Further, since a silicon substrate is used as a substrate for forming the optical waveguide, the loss of light propagating through the optical waveguide may increase.
[0054]
On the other hand, in the optical waveguide device shown in FIGS. 1 and 2, the glass substrate 10 is used, and the side faces of the optical waveguides 21, 22, 31, and 32 on which the heaters 26, 27, 36, and 37 are respectively installed. In addition, grooves 41 to 45 are formed as a substrate removal part to a depth of 70% or more of the thickness of the glass substrate 10. Accordingly, the configuration is such that light is propagated with low loss in the optical waveguide, and the optical characteristics of the optical waveguide can be efficiently controlled by the heater. Further, the manufacturing process is simplified as compared with the configuration in which the substrate portion immediately below the optical waveguide is removed or the configuration in which the substrate is a composite substrate, so that the productivity is improved.
[0055]
The configuration and effects of the optical waveguide device shown in FIGS. 1 and 2 will be described more specifically.
[0056]
First, the power consumption and the amount of heat generated by the heater of each channel in the optical waveguide device of the above embodiment will be discussed.
[0057]
When taking advantage of the optical circuit using a planar optical waveguide that integration is possible, use a configuration in which a light receiving element such as a photodiode and other optical elements are integrated with the planar optical waveguide on a substrate. Is assumed. Here, the operation compensation range of a general photodiode is up to about 85 ° C., and the use of an optical waveguide needs to be guaranteed up to about 70 °. Under such conditions, the temperature rise allowed for the optical waveguide is up to 15 ° C.
[0058]
FIG. 3 is a graph showing the dependence of the temperature of the optical waveguide on the power consumption. In this graph, the horizontal axis indicates the power consumption (mW) of the heater. The vertical axis indicates the temperature (° C.) of the optical waveguide heated by the heater. This graph shows actual measurement results using an optical waveguide device attached to a heat sink having a size of 70 mm × 35 mm, which is a size that can be actually used.
[0059]
According to the graph shown in FIG. 3, the temperature rises by 15 ° C. with power consumption of about 1 W against the environmental temperature of 25 ° C., and the temperature of the optical waveguide becomes 40 ° C. Here, assuming an eight-channel optical waveguide device, the permissible power consumption per channel is 125 mW. Further, in consideration of manufacturing tolerance and the like, it is preferable to design the optical waveguide device such that the power consumption per channel is 110 mW or less.
[0060]
Next, the accuracy required for controlling the temperature of the adjacent optical waveguide in the optical waveguide device will be discussed.
[0061]
In a configuration in which the optical waveguide is branched into the optical waveguides 21 and 22 in two paths as in the optical circuit unit 2 in the optical waveguide device illustrated in FIG. 1, the temperature between these optical waveguides 21 and 22 is increased. The difference control requires an accuracy of temperature control of about 0.4 ° C. in consideration of the accuracy of the phase difference control and the like. The maximum temperature difference required between the optical waveguides 21 and 22 is 15 ° C. as described above. On the other hand, in the optical waveguide device having the optical circuit units 2 and 3 of a plurality of channels as described above, when the temperature in the optical circuit unit of each channel is changed, the optical circuit unit of another channel is connected to the optical circuit unit. The effect is a problem.
[0062]
For example, in FIG. 2, the optical waveguides 21 and 22 are paired optical waveguides in the first optical circuit unit 2. The optical waveguides 31 and 32 are optical waveguides that are paired in the second optical circuit unit 3. In such a configuration, in a state where the temperature difference between the optical waveguides 31 and 32 is controlled to a constant temperature difference in the second optical circuit unit 3, the second optical circuit unit 3 is installed on the adjacent first optical circuit unit 2. Consider turning on / off the heater.
[0063]
In such a case, what has the greatest effect on the second optical circuit unit 3 is a state change in which the heater 27 provided for the optical waveguide 22 changes from OFF to ON. When the heater 27 is turned on, the temperature of the optical waveguide 22 becomes higher than the optical waveguide 21 by 15 ° C. as described above. At this time, by turning on the heater 27 for the optical waveguide 22 in the optical circuit section 2, the temperature of each of the optical waveguides 31 and 32 in the adjacent optical circuit section 3 and the temperature difference between the optical waveguides 31 and 32 are increased. Greatly varies, it becomes impossible for the optical circuit section of each channel to maintain the characteristics as an optical component. Specifically, considering that the accuracy required for controlling the temperature difference between the branched optical waveguides is 0.4 ° C., the temperature fluctuation due to the influence of the heater on the adjacent optical waveguide is half that. It is necessary to be 0.2 ° C. or less.
[0064]
Regarding such a problem, when the heater 27 is heated so that the temperature of the optical waveguide 22 becomes higher than the optical waveguide 21 by 15 ° C. in the optical circuit section 2, the optical waveguide 31 The temperature difference between the 32 was examined. Here, the temperature difference between the optical waveguides 31 and 32 is determined not by directly measuring the temperature but by measuring the transmission loss of the optical waveguides 30 to 33 by optical measurement and obtaining the optical waveguides 31 and 32 from the obtained loss values. The phase difference generated between them was calculated, and the temperature difference was further calculated from the obtained phase difference.
[0065]
FIG. 4 shows (a) the dependence of the temperature difference between the optical waveguides on the depth of the groove, and (b) the power consumption of the heater in the groove of the optical waveguide device using the glass substrate 10 having a thickness d0 = 500 μm. 9 is a graph showing the dependence on the depth.
[0066]
In the graph of FIG. 4A, the horizontal axis indicates the depth d2 (μm, see FIG. 2) of the removed portion of the glass substrate in the groove formed between the optical waveguides. The vertical axis indicates a temperature difference (° C.) generated between the optical waveguides 31 and 32 under the above conditions. In the graph of FIG. 4B, the horizontal axis represents the depth d2 (μm) of the removed portion of the glass substrate in the groove formed between the optical waveguides. The vertical axis indicates the power consumption (mW) of the heater required to realize the above conditions.
[0067]
FIG. 5 shows (a) the dependence of the temperature difference between the optical waveguides on the depth of the groove, and (b) the power consumption of the heater in the optical waveguide device using the glass substrate 10 having a thickness d0 = 300 μm. It is a graph which shows the dependence on the depth of a groove | channel.
[0068]
In the graph of FIG. 5A, the horizontal axis indicates the depth d2 (μm) of the removed portion of the glass substrate in the groove formed between the optical waveguides. The vertical axis indicates a temperature difference (° C.) generated between the optical waveguides 31 and 32 under the above conditions. In the graph of FIG. 5B, the horizontal axis represents the depth d2 (μm) of the removed portion of the glass substrate in the groove formed between the optical waveguides. The vertical axis indicates the power consumption (mW) of the heater required to realize the above conditions.
[0069]
First, in the graphs of the power consumption of the heaters shown in FIGS. 4B and 5B, the depth d2 of the groove in the substrate portion is not limited to the case where the thickness d0 of the glass substrate 10 is 500 μm or 300 μm. Is set to 50 μm or more, the condition that the power consumption of the heater per channel is 110 mW or less is satisfied. This is because the glass substrate 10 has a relatively low thermal conductivity and a small escape of heat.
[0070]
On the other hand, in the graph of the temperature difference shown in FIGS. 4A and 5A, in the case of FIG. 4A where the thickness d0 of the glass substrate 10 is 500 μm, the generated temperature difference is 0.2 ° C. or less. In order to achieve this, the depth d2 of the groove in the substrate must be 350 μm or more. In the case of FIG. 5A in which the thickness d0 is 300 μm, the depth d2 of the groove needs to be 210 μm or more in order to make the generated temperature difference 0.2 ° C. or less.
[0071]
As described above, in order to reduce the power consumption of the heater per channel to 110 mW or less and to reduce the temperature fluctuation due to the influence of the heater on the adjacent optical waveguides to 0.2 ° C. or less, as described above, the distance between the optical waveguides is set. It can be seen that the substrate removal portion in the above process may be formed to a depth of 70% or more of the thickness of the glass substrate.
[0072]
Here, in the optical waveguide device shown in FIG. 1, a substrate is provided on each of the optical waveguides 21, 22, 31, and 32 on one side and the other side of the optical waveguide so that the optical waveguide is sandwiched therebetween. A configuration in which a groove serving as a removal portion is provided is used. Thereby, in the optical waveguide in which the heater is installed, diffusion of heat to other portions in the optical waveguide layer can be effectively suppressed. In the configuration of FIG. 1, the grooves 42, 43, and 44 are commonly used as substrate removal parts for the optical waveguides located on both sides thereof.
[0073]
Further, in such a configuration, the distance between the substrate removing portions provided on both sides, for example, the groove 41 provided on the left side with respect to the optical waveguide 21 provided with the heater 26 and the groove 42 provided on the right side Is preferably 70 μm or more and 150 μm or less. Thereby, the optical waveguide can be suitably configured by the core layer 15 and the cladding layer 16 in the path where the heater is installed.
[0074]
That is, when the interval between the groove portions is smaller than 50 μm, light propagating in the core portion corresponding to the optical waveguide and the vicinity thereof leaks to the substrate removing portion, and the light transmission loss increases. For this reason, it is preferable that the interval between the groove portions is 50 μm or more, and it is preferable that the interval is 70 μm or more in consideration of processing accuracy or the like when forming the groove portion.
[0075]
On the other hand, when the interval between the groove portions is larger than 150 μm, the efficiency of heating the optical waveguide by the heater is reduced, and in some cases, the condition that the power consumption of the heater per channel is 110 mW or less cannot be satisfied. Therefore, it is preferable that the interval between the groove portions is 150 μm or less.
[0076]
However, the substrate removal portion such as the groove is generally formed on at least one side of the optical waveguide on which the heater is installed, thereby improving the efficiency of controlling the optical characteristics of the optical waveguide. can do. Whether the substrate removal portion is provided on one side of the optical waveguide or on both sides is designed according to the degree of integration of the optical circuit in each optical waveguide device, a specific waveguide pattern, and the like. Is preferred.
[0077]
As for the specific configuration of the substrate removing unit, focusing on the substrate removing unit formed for the optical waveguide 21 and the heater 26, in the optical waveguide device shown in FIGS. Grooves 41 and 42 which are groove-shaped substrate removing portions extending along the wave path 21 are formed. However, a substrate removing unit having another configuration may be used as the substrate removing unit.
[0078]
FIGS. 6A to 6C are plan views showing modified examples of the substrate removing portion formed in the optical waveguide device shown in FIG. In FIG. 6A, an example of the groove 41a, 41b and the groove 42a, 42b each having the optical waveguide 21 interposed therebetween, instead of the groove 41 and the groove 42 formed with the optical waveguide 21 interposed therebetween, is shown. Is shown. FIG. 6B shows an example of a substrate removing unit 41c and a substrate removing unit 42c in which a plurality of cylindrical substrate removing units are continuously arranged along the optical waveguide 21. FIG. 6C shows an example of a substrate removing unit 41d and a substrate removing unit 42d in which a plurality of cylindrical substrate removing units are arranged at regular intervals along the optical waveguide 21. Further, in addition to these configurations, a substrate removing section having various configurations may be used.
[0079]
Next, a method of manufacturing the optical waveguide device shown in FIGS. 1 and 2 will be described. FIGS. 7A to 7D are process diagrams illustrating an example of a method for manufacturing the above-described optical waveguide device. 7A to 7D, each step is illustrated by a cross-sectional view corresponding to the cross-sectional view illustrated in FIG.
[0080]
In the manufacturing method shown in FIG. 7, a glass substrate 10 serving as a substrate for forming an optical waveguide is prepared, and an optical waveguide film 14 is formed on the glass substrate 10 (FIG. 7A). Then, the optical waveguide film 14 is patterned by the waveguide pattern shown in FIG. 1 including a plurality of paths, and the core layers 15 each functioning as an optical waveguide are manufactured (FIG. 7B).
[0081]
Next, a cladding layer 16 having a lower refractive index than the core layer 15 is formed so as to cover the glass substrate 10 and the patterned core layer 15 (FIG. 7C). Thus, an optical waveguide layer including the core layer 15 and the cladding layer 16 is formed on the glass substrate 10 (optical waveguide forming step).
[0082]
Subsequently, heaters 26, 27, 36, and 37 as heating means are installed on the cladding layer 16 of the optical waveguide layer located above the core layer 15 corresponding to a predetermined path among the plurality of paths of the optical waveguide. (Heating means installation step). Further, at predetermined positions between the respective optical waveguides, grooves 41 to 45, which are substrate removal parts, are formed to penetrate the cladding layer 16 of the optical waveguide layer to a depth of 70% or more of the thickness of the glass substrate 10. (Substrate removal part forming step). Thus, an optical waveguide device having the configuration shown in FIGS. 1 and 2 is obtained (FIG. 7D).
[0083]
Here, as for a specific method for forming the substrate-removed portion such as the groove portion, it is preferable to form the substrate by any one of processing using a dicer, etching, and laser processing. When the substrate removing portion is formed using a dicer, it is preferable to use a dicer having a blade diameter of about 60 mm or less, or 60 mm or less in order to form the substrate removing portion satisfactorily.
[0084]
Subsequently, a modified example of the optical waveguide device shown in FIGS. 1 and 2 will be described. In FIGS. 8 to 10 described below, the optical waveguide in each embodiment is shown by a cross-sectional view corresponding to the cross-sectional view shown in FIG. 2 and taken along a direction perpendicular to the light transmission direction in the optical circuit 1. 1 shows a cross-sectional structure of a device. In each of the embodiments described below, the planar structure of the optical waveguide device is the same as that shown in FIG.
[0085]
FIG. 8 is a cross-sectional view illustrating a configuration of the second embodiment of the optical waveguide device. The optical waveguide device shown in FIG. 8 has the same configuration as that of the optical waveguide device shown in FIGS. 1 and 2, but differs in the configuration of the grooves 41 to 45 which are the substrate removal portions.
[0086]
That is, in the present embodiment, each of the grooves 41 to 45 is filled with the filling material 40 made of a predetermined heat insulating material. With such a configuration, it is possible to improve the effect of suppressing the diffusion of heat by the substrate removing portion with respect to the diffusion of heat from the optical waveguide provided with the heater.
[0087]
On the opposite side of the glass substrate 10 from the optical waveguide layer, a heat radiating plate 50 is provided as a member made of a material having higher thermal conductivity than the glass substrate 10. The heat sink 50 is provided so as to be in thermal contact with the glass substrate 10. Thereby, excess heat in the optical waveguide layer including the core layer 15 and the cladding layer 16 and in the glass substrate 10 can be efficiently released to the outside.
[0088]
As such a heat radiating plate 50, for example, a metal plate can be used. As a method of contacting the glass substrate 10 and the heat sink 50, a method of bonding with an adhesive having a high thermal conductivity, a method of contacting via a grease having a high thermal conductivity, or the like can be used. Note that, in the graphs of FIGS. 3 to 5, in the optical waveguide device having the configuration shown in FIGS. 1 and 2, an experiment was performed with the glass substrate 10 fixed to a metal radiator plate.
[0089]
FIG. 9 is a cross-sectional view illustrating the configuration of the third embodiment of the optical waveguide device. The optical waveguide device shown in FIG. 9 has a configuration similar to that of the optical waveguide device shown in FIGS. 1 and 2, but differs in the configuration of the optical waveguide layer including the core layer and the cladding layer.
[0090]
That is, in the present embodiment, in the optical waveguide layer formed on the glass substrate 10, in addition to the core layer 15 and the overcladding layer 16, the underlayer is formed between the glass substrate 10 and the core layer 15 and the overcladding layer 16. A cladding layer 17 is provided. As described above, the optical waveguide layer is not limited to the configuration in which the core layer 15 is formed directly on the glass substrate 10, but may be a configuration in which the under cladding layer 17 is provided. However, the configuration of FIG. 2 without the under clad layer has an advantage that the manufacturing process is simplified as compared with the configuration of FIG.
[0091]
FIG. 10 is a sectional view showing the configuration of the fourth embodiment of the optical waveguide device. The optical waveguide device shown in FIG. 10 has the same configuration as that of the optical waveguide device shown in FIGS. 1 and 2, but differs in the configuration of the grooves 41 to 45 which are the substrate removing portions.
[0092]
That is, in the present embodiment, the grooves 41 to 45 are formed so as to penetrate the entire optical waveguide layer up to the cladding layer 16 and the glass substrate 10. As described above, the substrate removing portion formed between the optical waveguides is preferably formed to a depth of 70% or more of the thickness of the glass substrate, and thus the substrate is removed so as to penetrate the glass substrate. Forming a part is also included.
[0093]
The optical waveguide device and the method for manufacturing the same according to the present invention are not limited to the above-described embodiments, and various modifications are possible. For example, FIGS. 1 and 2 show an optical waveguide device using a planar waveguide type optical circuit 1 having a configuration having two-channel optical circuit portions 2 and 3, but only one channel or an optical circuit having three or more channels. It may be configured to have a portion.
[0094]
【The invention's effect】
The optical waveguide device and the manufacturing method thereof according to the present invention have the following effects as described in detail above. That is, according to a configuration in which a glass substrate is used as a substrate for forming a planar waveguide type optical waveguide, and a substrate removing portion is formed on a side of the optical waveguide in a path where a heating unit is installed, a heater or the like is used. Thus, an optical waveguide device capable of efficiently controlling the temperature of the optical waveguide by the heating means, and controlling the optical characteristics of the optical waveguide by the heating means, and a method of manufacturing the same can be obtained. Further, by forming the substrate removal portion to a depth of 70% or more of the thickness of the glass substrate, controllability of the optical characteristics of the optical waveguide is improved, and influence on the optical waveguide in other paths is reduced. Can be realized.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a first embodiment of an optical waveguide device.
FIG. 2 is a cross-sectional view taken along a line II of FIG. 1, showing a cross-sectional structure of the optical waveguide device shown in FIG. 1 perpendicular to a light transmission direction.
FIG. 3 is a graph showing the dependence of the temperature of an optical waveguide on power consumption.
FIG. 4 shows (a) the dependence of the temperature difference between optical waveguides on the depth of the groove, and (b) the power consumption of the heater with respect to the depth of the groove in an optical waveguide device using a glass substrate having a thickness of 500 μm. It is a graph which shows dependency.
FIG. 5 shows (a) dependence of temperature difference between optical waveguides on groove depth, and (b) power consumption of heater with respect to groove depth in an optical waveguide device using a glass substrate having a thickness of 300 μm. It is a graph which shows dependency.
FIG. 6 is a plan view showing a modification of the substrate removing portion formed in the optical waveguide device shown in FIG.
FIG. 7 is a process chart showing an example of a method for manufacturing the optical waveguide device shown in FIG.
FIG. 8 is a cross-sectional view illustrating a configuration of a second embodiment of the optical waveguide device.
FIG. 9 is a cross-sectional view illustrating a configuration of a third embodiment of the optical waveguide device.
FIG. 10 is a cross-sectional view illustrating a configuration of a fourth embodiment of the optical waveguide device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Planar waveguide optical circuit, 10 ... Glass substrate, 11 ... Input end face, 12 ... Output end face, 14 ... Optical waveguide film, 15 ... Core layer, 16 ... Over clad layer, 17 ... Under clad layer, 2 ... 1 optical circuit section, 20 to 23 optical waveguide, 26, 27 heater, 3 second optical circuit section, 30 to 33 optical waveguide, 36, 37 heater, 40 filling material, 41 to 45 groove section ( (Substrate removal part), 50 ... heat sink.

Claims (9)

A glass substrate made of a predetermined glass material,
A core layer formed by a waveguide pattern including a plurality of paths on the glass substrate and functioning as an optical waveguide,
A cladding layer formed so as to cover the glass substrate and the core layer, and constituting an optical waveguide layer together with the core layer;
Heating means installed on the optical waveguide layer for a predetermined path among the plurality of paths of the optical waveguide, and used for temperature control of the optical waveguide in the predetermined path,
With respect to the optical waveguide in the predetermined path in which the heating means is provided, at a predetermined position on at least one side of the optical waveguide, the thickness of the glass substrate through the optical waveguide layer is reduced. An optical waveguide device comprising: a substrate removing portion formed to a depth of 70% or more. The optical waveguide device according to claim 1, wherein the core layer is formed directly on the glass substrate. The substrate removing portion is formed at predetermined positions on one side and the other side of the optical waveguide on the predetermined path, respectively, with the optical waveguide interposed therebetween. Optical waveguide device. An interval between the substrate removing portion provided on one side of the optical waveguide in the predetermined path and the substrate removing portion provided on the other side is 70 μm or more and 150 μm or less. The optical waveguide device according to claim 3. 2. The optical waveguide device according to claim 1, wherein a predetermined heat insulating material is filled in the inside of the substrate removing portion. On the opposite side of the glass substrate from the optical waveguide layer, a member made of a material having a higher thermal conductivity than the glass substrate is provided so as to be in thermal contact with the glass substrate. The optical waveguide device according to claim 1, wherein On a glass substrate made of a predetermined glass material, a core layer having a waveguide pattern including a plurality of paths and functioning as an optical waveguide, and forming an optical waveguide layer together with the core layer covering the glass substrate and the core layer. An optical waveguide forming step of forming a cladding layer to be formed,
For a predetermined path among the plurality of paths of the optical waveguide, a heating unit setting step of setting a heating unit used for controlling the temperature of the optical waveguide in the predetermined path on the optical waveguide layer,
With respect to the optical waveguide in the predetermined path in which the heating means is provided, at a predetermined position on at least one side of the optical waveguide, the thickness of the glass substrate through the optical waveguide layer is reduced. Forming a substrate-removed portion to a depth of 70% or more. 8. The method of manufacturing an optical waveguide device according to claim 7, wherein in the optical waveguide forming step, the core layer is formed directly on the glass substrate. 8. The method of manufacturing an optical waveguide device according to claim 7, wherein in the substrate removing section forming step, the substrate removing section is formed by any one of processing using a dicer, etching processing, and laser processing.

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