JP4831667B2 - Filter built-in type optical waveguide, WDM module, optical integrated circuit, and manufacturing method thereof - Google Patents

Description

  The present invention is particularly useful for CWDM (Coarse Wavelength Division Multiplexing), an optical waveguide with a built-in filter and a WDM module capable of high-speed optical signal transmission by WDM (Wavelength Division Multiplexing), and The present invention relates to an optical integrated circuit using them.

  Conventionally, a WDM module has a configuration in which a multiplexer / demultiplexer is mounted on an optical element as a separate component separate from the optical waveguide, and an optical input / output optical waveguide is connected to the multiplexer / demultiplexer. Is known (for example, see Non-Patent Documents 1 and 2). Non-Patent Document 1 discloses a 4-wave multiplexing CWDM module having a wavelength of 990 to 1080 nm, and Non-Patent Document 2 discloses an 8-wave multiplexing CWDM module having a wavelength of 778 to 864 nm.

In addition to these, research and development is actively progressing on optical communication using WDM. For example, it is known to insert a WDM filter having wavelength selectivity into an oblique groove provided in an optical waveguide. (For example, see Patent Documents 1-3). Patent Document 3 uses a filter made of a transparent dielectric multilayer film as a WDM filter, and realizes desired reflection / transmission characteristics by alternately laminating two or more kinds of dielectric films having different refractive indexes. Is disclosed.
Brian E. Lemoff et.al., "MAUI: Enabling Fiber-to-the-Processor WithParallel Multiwavelength Optical Interconnects", JOURNAL OF LIGHTWAVETECHNOLOGY, VOL.22, NO.9, pp.2043-2054, 2004. Eric B. Grann, "Low Cost CWDM Optical Transceivers", Proc. 51st Electronic Components Technological Conference, pp. 26-29, 2001. JP 2005-94160 A JP 2004-20973 A JP 2003-258364 A

  However, in the conventional WDM module, the multiplexer / demultiplexer is a separate block component from the optical waveguide, and although the miniaturization is progressing, there is a limit to the reduction in the overall size of the module.

  Even in the conventional structure in which the WDM filter is inserted into the groove of the optical waveguide, the WDM filter is significantly larger than the optical waveguide, and it can be said that it is a separate component, which is far from being a structure in which the optical waveguide and the WDM filter are integrated. Is.

  Therefore, in view of the circumstances as described above, the present invention has an optical waveguide having a multiplexing / demultiplexing function, miniaturization of the module size, and assembly by high-density mounting in which the optical waveguide and the multiplexer / demultiplexer are integrated. It is an object of the present invention to provide an optical waveguide with a built-in filter that can reduce costs by reducing the number of steps, and a small and inexpensive WDM module and an optical integrated circuit using the optical waveguide.

An optical waveguide with a built-in filter according to the present invention solves the above-described problems by combining light of wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n incident from an optical element into the core of the optical waveguide. Or splitting the light in the core of the optical waveguide into light of wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n and emitting the light to the optical element, each wavelength λ ₁ , λ ₂ , λ _3. A plurality of multiplexing / demultiplexing filters corresponding to λ _n are juxtaposed along the light guiding direction in the optical waveguide, and each multiplexing / demultiplexing filter has wavelengths λ ₁ and λ _{2 that} it is responsible for. , Λ ₃ ... Λ _n is reflected, and the other wavelengths are transmitted.

  Second, each multiplexing / demultiplexing filter is formed of a dielectric multilayer filter or a chirped grating filter.

  Thirdly, each multiplexing / demultiplexing filter is characterized by being composed of a dielectric multilayer filter provided obliquely with respect to the optical axis.

  Fourth, each multiplexing / demultiplexing filter is composed of a chirped grating filter that is positioned immediately above the light emission center or the light receiving center of the optical element and is formed obliquely with respect to the optical axis. The diffraction grating is tilted with respect to the optical axis and the pitch between the diffraction gratings is chirped so that the diffracted light satisfies the Bragg condition and has a focal point at the light emission center or light reception center of the optical element. It is characterized by.

  Fifth, each multiplexing / demultiplexing filter is composed of a chirped grating filter provided obliquely to the optical axis, and the incident angle or diffraction of light from the optical element to the diffraction grating of the chirped grating filter. As the light emission angle from the grating to the optical element increases, the tilt angle of the diffraction grating with respect to the optical axis decreases and the pitch between the diffraction gratings increases.

  Sixth, a plurality of slits are provided in the optical waveguide, and a multiplexing / demultiplexing filter is inserted into each slit.

  Seventh, the optical waveguide is an optical waveguide film or an optical fiber.

  The WDM module according to the present invention is characterized in that, in order to solve the above-mentioned problems, eighthly, the optical waveguide with a built-in filter is provided.

  Ninth, the optical waveguide with a built-in filter is provided on an optical element.

Tenth, the filter-embedded optical waveguide is provided on an optical element that emits or receives light of wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n , The multiplexing / demultiplexing filter is characterized in that it is in a position where light of the wavelength can enter and exit each other.

  Eleventh, an optical element is embedded in the optical waveguide with a built-in filter.

  The optical integrated circuit according to the present invention solves the above-mentioned problem. Twelfth, the optical I / O port of each semiconductor chip is optically wired by the filter built-in type optical waveguide. Features.

  13thly, the said WDM module comprises the optical I / O port of each semiconductor chip and the optical wiring which connects it.

  According to the first to seventh inventions, the optical waveguide itself is provided with the multiplexing / demultiplexing filter as described above in the optical waveguide, so that the optical waveguide itself has a multiplexing / demultiplexing function. An integrated high-density mounting is possible, thereby providing an optical waveguide with a built-in filter that realizes minimization of the WDM module size and cost reduction by reducing assembly man-hours.

  According to the eighth to eleventh aspects of the present invention, there is provided a small and low-cost WDM module comprising the filter built-in type optical waveguide as described above together with an optical element having a light receiving / emitting function.

  According to the twelfth and thirteenth inventions, a compact and low-cost optical integrated circuit using the filter built-in type optical waveguide or the WDM module as an optical wiring or an optical I / O port is realized.

[Embodiment 1 regarding filter built-in type optical waveguide and WDM module]
1 and 2 each show an embodiment of the present invention.

  1 and 2, 1 is an optical waveguide with a built-in filter, 2 is an optical waveguide, 3a, 3b, 3c and 3d are multiplexing / demultiplexing filters (also called WDM filters), 4a, 4b, 4c and 4d are optical elements. Reference numeral 10 denotes a four-wavelength multiplexing WDM module in which the filter built-in type optical waveguide 1 and the optical elements 4a, 4b, 4c, and 4d are integrated.

  First, the filter built-in type optical waveguide 1 includes four optical multiplexing / demultiplexing filters 3a, 3b, 3c, and 3d in an optical waveguide 2 having a core 21 and a clad 22.

  The multiplexing / demultiplexing filters 3 a, 3 b, 3 c, 3 d are arranged in parallel along the light guide direction in the optical waveguide 2. For example, a plurality of slits oblique to the optical axis are centered on the core 21. And is fixedly inserted into this. As an example of the dimensions, slits having a width of about 20 μm and a depth of about 500 μm are provided at intervals of 250 μm along the core 21 and inserted into them.

  The insertion process can be performed by, for example, a commercially available automatic machine as illustrated in FIGS. 3 and 4. More specifically, first, the optical waveguide 2 in which the required number of slits 30a, 30b, 30c, and 30d are formed in advance is fixed to a stage 9 provided at a predetermined angle within a range of up to about 45 degrees by a vacuum chuck or the like. To do. On the other hand, vacuum chucking of the multiplexing / demultiplexing filters 3a, 3b, 3c, 3d is performed using a probe 31 provided in a commercially available automatic machine or the like. Then, the multiplexing / demultiplexing filters 3a, 3b, 3c, and 3d maintaining this state are dropped into the corresponding slits 30a, 30b, 30c, and 30d in order, and bonded with a translucent resin. Of course, as shown in FIG. 4, a plurality of filters 3a, 3b, 3c, 3d can be formed as one component and can be mounted together.

Each of these multiplexing / demultiplexing filters 3a, 3b, 3c, 3d multiplexes the light of wavelengths λ ₁ , λ ₂ , λ ₃ , λ ₄ incident from the optical elements 4a, 4b, 4c, 4d to provide a single optical signal. Wavelength multiplexed light that is guided into the core 21 of the waveguide 2 (see FIG. 1) or travels through the core 21 of one optical waveguide 2 is split into light of wavelengths λ ₁ , λ ₂ , λ ₃ , and λ _4. Are emitted to the optical elements 4a, 4b, 4c, and 4d (see FIG. 2), reflect one of the wavelengths λ ₁ , λ ₂ , λ ₃ , and λ ₄ respectively, It has wavelength selectivity for transmission.

For example, in FIG. 1, the multiplexing / demultiplexing filter 3a reflects only the wavelength λ ₁ and transmits the other wavelengths λ ₂ , λ ₃ and λ ₄ , and the multiplexing / demultiplexing filter 3b reflects only the wavelength λ _2. Λ ₁ , λ ₃ , and λ ₄ are transmitted, and the subsequent multiplexing / demultiplexing filters 3c and 3d have the same wavelength selectivity.

  More specifically, it is preferable to use a dielectric multilayer filter or a chirped grating filter as the multiplexing / demultiplexing filters 3a, 3b, 3c, 3d.

  In the case of a dielectric multilayer filter, a filter produced according to the target wavelength band is used, and the dimensions and shape are, for example, in the case of 4 element array / wavelength, thickness 20 μm, height 0.5 mm or less, width 1 to A rectangular parallelepiped filter of about 2.5 mm can be employed.

  As for the filter characteristics, for example, the CWDM wavelength interval of each filter is 10 to 20 nm, each filter band is +/− 5 to 10 nm (in the case of −3 dB), and the insertion loss is 1 to 2 dB or less.

In the case of the chirped grating filter, for example, as illustrated in FIG. 5, the emission centers of the optical elements 4a, 4b, 4c, and 4d that are responsible for the same wavelength among the wavelengths λ ₁ , λ ₂ , λ ₃ , and λ ₄ , respectively. Alternatively, it is located immediately above the light receiving center and is formed obliquely with respect to the optical axis. In the filter, the diffracted light satisfies the Bragg condition and is located at the light emitting center or the light receiving center of the optical elements 4a, 4b, 4c, 4d. In order to have a focal point, the diffraction grating is tilted with respect to the optical axis within a predetermined range of angles, and the pitch between the diffraction gratings is chirped or changed within a predetermined range.

  That is, the incident angle θ of light from the optical elements 4a, 4b, 4c, 4d to the diffraction grating of the chirped grating filter or the emission angle θ of light from the diffraction grating to the optical elements 4a, 4b, 4c, 4d is large. Accordingly, the inclination angle of the diffraction grating with respect to the optical axis is set to be small and the pitch between the diffraction gratings is set to be large.

  In the embodiment of FIG. 5, each diffraction grating of each chirped grating filter has a light incident angle θ (an outgoing angle θ in the case of demultiplexing) that increases from left to right in the figure. In accordance with this, the inclination angle of the light with respect to the optical axis is gradually reduced and the pitch is increased.

  As specific numerical examples, for example, in the case of a wavelength of 0.63 nm, an angle range of 45.7 ° to 46.4 °, a pitch of 0.294 μm to 0.302 μm, a grating length of 100 μm, and about 100 diffraction gratings. Can be set. For other wavelengths as well, the values are set in the same numerical range as appropriate.

  As for the material, for example, epoxy can be used in the 0.85 μm short wavelength band, and fluorinated polyimide can be used in the 1.3 μm long wavelength band.

  The fabrication method is, for example, the well-known holographic interferometry (Stephen M. Schultz et.al, “Volume grating preferential-order focusing waveguide coupler”, OPTICS LETTERS). , Vol.24, No.23, 1999).

  By the multiplexing / demultiplexing filters 3a, 3b, 3c, and 3d as described above, the optical waveguide 1 with a built-in filter in which the optical waveguide 2 itself has a wavelength branching and inserting function, that is, a multiplexing / demultiplexing function, is realized. Become.

  The numerical values and materials described above are merely examples, and are not particularly limited as long as an appropriate WDM can be realized in a state of being incorporated in the optical waveguide 2.

  As the optical waveguide 2 into which the multiplexing / demultiplexing filters 3a, 3b, 3c, 3d are incorporated, an optical waveguide film, an optical fiber, or the like can be adopted.

  In any case of these optical waveguide films and optical fibers, the filter-embedded optical waveguide 1 including the multiplexing / demultiplexing filters 3a, 3b, 3c, 3d is provided on the optical elements 4a, 4b, 4c, 4d. Can be mounted in contact with each other (see FIG. 1 and FIG. 2) or close to each other (see FIG. 5), thereby realizing a four-wavelength multiplexing WDM module 10 with a reduced height. Is done.

  At this time, the optical elements 4a, 4b, 4c, and 4d in charge of the same wavelength and the multiplexing / demultiplexing filters 3a, 3b, 3c, and 3d are aligned so that light of the wavelengths can enter and exit each other.

For the optical elements 4a, 4b, 4c, and 4d, light emitting elements and light receiving elements such as vertical cavity surface emitting lasers (VCSEL) that operate at different wavelengths λ ₁ , λ ₂ , λ ₃ , and λ ₄ are used. be able to. In the embodiment of FIG. 1 and FIG. 2, on the wiring substrate 5 provided with the through electrode 51 and the thin film wiring 52, the wavelength interval is integrated and mounted in a row in units of several nanometers to several tens of nanometers. The driving IC 6 is controlled.

In addition, for example, one monolithic array form having each wavelength or a plurality of individual element forms for each wavelength can be adopted. In any case, the interval between the light emitting points or the light receiving points can be set to about 250 μm, for example. Of course, they can also be arranged in the depth direction perpendicular to the drawing, and in this case as well, by arranging and aligning them in the depth direction, for example, an interval between light emitting points or light receiving points of about 250 μm can be obtained. Of course, it goes without saying that not only four wavelength multiplexing but also wavelength multiplexing of less or more than that is possible. In accordance with the number n of wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n to be multiplexed by division, the multiplexing / demultiplexing filter 3 is built in the optical waveguide 2 in the same manner as in the above-described embodiment, and the optical element 4 is connected to the wiring board. 5 and can be integrated, and a WDM module 10 that is particularly useful for CWDM can be realized.

  As a mounting form of the WDM module 10 described above, a TRx transceiver module form in which a single filter built-in type optical waveguide 1 is mounted on a light emitting element and a light receiving element, or an individual filter built-in type optical waveguide 1 is used as a light emitting element and a light receiving element, respectively. A transmission Tx and reception Rx module configuration mounted one-to-one on the light receiving element can be considered.

  Further, for example, in addition to mounting the filter built-in type optical waveguide 1 on the optical element 4, it is possible to form the optical element 4 on the filter built-in type optical waveguide 1. In any form, for example, as illustrated in FIG. 6, the translucent resin 7 can be used to directly attach the resin by resin curing adhesion by UV light irradiation, heating, or the like.

  As the optical element 4 in this case, an optical element having a thickness of about 10 μm by an epitaxial lift-off (abbreviation ELO) or the like can be adopted as well as a normal thickness.

  The optical element 4 in FIG. 6 has an electrode 40 protruding on the side opposite to the side bonded to the filter-incorporated optical waveguide 1, through which an electric substrate 8 (or a semiconductor element such as an LSI) is electrically connected. Connected.

[Embodiment 2 regarding filter built-in type optical waveguide and WDM module]
Regarding the relationship between the filter built-in type optical waveguide 1 and the optical element 4, a form in which the optical element 4 is embedded in the filter built-in type optical waveguide 1 is also possible, as exemplified in FIGS. 7 and 8.

  In FIG. 7, the optical element 4 is embedded in the support substrate 23 constituting the optical waveguide 2 of the filter-embedded optical waveguide 1. In FIG. 8, it is buried in the clad 22 constituting the optical waveguide 2 in the form without the support substrate 23.

  As the optical element 4 in these cases, for example, one obtained by slicing to a thickness of about 10 μm by ELO or the like is preferable.

  The optical element 4 in FIG. 7 includes an electric substrate 8 (or a semiconductor such as an LSI) in contact with the bottom of the support substrate 23 through a protruding electrode 40 provided therein and a through-hole electrode 231 penetratingly formed in the support substrate 23. Device). In the optical element 4 of FIG. 8, only the electrode 40 protrudes to the outside of the clad 22 and is electrically connected to the electric substrate 8 disposed close to the bottom of the clad 22.

  In the embodiment shown in FIG. 7, the support substrate 23 is made of the same clad material as the clad 22, such as a polymer material, and the optical waveguide 2 is integrated with the core 21 and the clad 22. Of course, a polymer material different from the clad material can be used as the support substrate 23.

  Any process technology enables further miniaturization of the WDM module 10.

[Embodiment 3 regarding filter built-in type optical waveguide and WDM module]
Here, an example of a manufacturing process of the filter built-in type optical waveguide 1 and the WDM module 10 illustrated in FIG. 7 will be described with reference to FIGS. 9A to 9E and FIGS. 10A to 10D as appropriate. To do.

  First, when the multiplexing / demultiplexing filter 3 is a dielectric multilayer filter or the like, as illustrated in FIG. 9A, an ELO or the like is formed on the optical waveguide 2 in which the slits 30 for the multiplexing / demultiplexing filter 3 are formed in advance. The optical element 4 having the protruding electrode 40 thinned by the step is directly attached by the translucent resin 7. The adhesion is performed by curing the translucent resin 7 by UV light irradiation or heating from the back surface. Subsequently, as illustrated in FIG. 9B, the support substrate 23 is coated by spin coating or the like so as to cover the optical element 4 and support the clad 22 using the same polymer material as that of the clad 22. Of course, a polymer material different from the clad material can be used as the support substrate 23. Next, as illustrated in FIG. 9C, the through-hole electrode 231 is formed on the support substrate 23. Then, as illustrated in FIGS. 9D and 9E, the multiplexing / demultiplexing filter 3 is inserted into the slit 30 with this mounted on the electric substrate 8 (or a semiconductor element such as LSI). See FIGS. 3 and 4 above for the filter insertion process.

  On the other hand, when the multiplexing / demultiplexing filter 3 is a chirped grating filter as illustrated in FIG. 5, the multiplexing / demultiplexing filter 3 is built in the optical waveguide 2 in advance as illustrated in FIG. As shown in FIGS. 10B to 10D, the support substrate 23 and the through-hole electrode 231 are formed on the filter-embedded optical waveguide 1 and the electric substrate 8 is formed. Perform mounting process.

[Embodiment related to optical integrated circuit]
By using the filter built-in type optical waveguide 1 and the WDM module 10 as described above, for example, as illustrated in FIG. 11, an optical integrated circuit that realizes optical transmission between the semiconductor chips such as the memory 102 and the CPU 103 in the board 101. 100 is realized.

  More specifically, in the embodiment of FIG. 11, the optical I / O port and the optical wiring that connect between the memory 102 and the CPU 103 on the board 101 multiplex the optical signals of the respective wavelengths from the memories 102. A WDM module 10a mounted as a so-called multiplexer (Multiplexer: abbreviated as MUX) that leads to a single filter-incorporated optical waveguide 1, and a wavelength-multiplexed optical signal transmitted through the filter-incorporated optical waveguide 1 to each original wavelength. The WDM module 10b is implemented as a so-called demultiplexer (demultiplexer: abbreviated as DEMUX) for demultiplexing.

  As a result, it is possible to realize an optical integrated circuit 100 in which further reduction in size and cost is achieved, in which inter-chip transmission is performed by the filter built-in type optical waveguide 1 and the WDM module 10.

  The optical integrated circuit 100 is not limited to the mounting form that can be called the bare chip form of FIG. 11, but can also be a module form such as transmission between boards such as routers and servers, and transmission between cases. The filter built-in type optical waveguide 1 and the WDM module 10 may be applied between boards or between cases.

  Any form enables high-density mounting in a narrower space than in the past.

It is sectional drawing which showed one Embodiment of the optical waveguide with a built-in filter of this invention, and a WDM module. It is sectional drawing which showed another one Embodiment of the optical waveguide with a built-in filter of this invention, and a WDM module. It is a figure for demonstrating a filter insertion process. It is a figure for demonstrating a filter insertion process. It is an expanded sectional view of a multiplexing / demultiplexing filter. It is sectional drawing which showed one Embodiment which affixed the optical element directly to the optical waveguide with a built-in filter. It is sectional drawing which showed one Embodiment which embedded the optical element in the optical waveguide with a built-in filter. It is sectional drawing which showed one Embodiment which embedded the optical element in the optical waveguide with a built-in filter. (A)-(e) is a figure for demonstrating a module preparation process. (A)-(d) is a figure for demonstrating a module preparation process. It is the top view which showed one Embodiment of the optical integrated circuit of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filter built-in type optical waveguide 2 Optical waveguide 21 Core 22 Clad 23 Support substrate 231 Through-hole electrode 3, 3a, 3b, 3c, 3d Multiplexing / demultiplexing filter 30a, 30b, 30c, 30d Slit 31 Probe 4, 4a, 4b, 4c , 4d Optical element 40 Electrode (projection electrode)
5 Wiring board 51 Through electrode 52 Thin film wiring 53 Solder ball 6 Drive IC
7 Translucent resin 8 Electric substrate (or semiconductor element such as LSI)
9 Stage 10, 10a, 10b WDM module 100 Optical integrated circuit 101 Board (substrate)
102 Memory 103 CPU

Claims (9)

A WDM module including an optical waveguide with a built-in filter having a multiplexing / demultiplexing function in an optical waveguide film itself as an optical waveguide,
A plurality of slits provided in the optical waveguide film;
Light of wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _n incident from the optical element into the optical waveguide film is multiplexed and guided in the core of the optical waveguide film along the light guide direction, or optical wavelength lambda ₁ light in the core of the waveguide film at the optical waveguide film in, lambda _2, lambda ₃ and demultiplexed into light · · · lambda _n to emit the optical element, the wavelength lambda _1, lambda _2, A plurality of multiplexing / demultiplexing filters corresponding to λ ₃ ... λ _n are provided in the filter built-in type optical waveguide,
The plurality of multiplexing / demultiplexing filters are inserted so as to be juxtaposed along the light guide direction of the optical waveguide film inserted into the plurality of slits of the optical waveguide film itself,
Each multiplexing / demultiplexing filter reflects one of the wavelengths λ ₁ , λ ₂ , λ ₃ ... Λ _{n that} it is responsible for and transmits the other wavelengths,
Each multiplexing / demultiplexing filter is composed of a chirped grating filter provided obliquely to the optical axis, and the incident angle of light from the optical element to the diffraction grating of the chirped grating filter or from the diffraction grating to the optical element. As the light exit angle increases, the tilt angle of the diffraction grating with respect to the optical axis decreases and the pitch between the diffraction gratings increases.
The WDM module , wherein the optical element is embedded in the filter built-in type optical waveguide.   2. The WDM module according to claim 1, wherein the optical element is embedded in a support substrate constituting the optical waveguide of the filter built-in type optical waveguide.   3. The WDM module according to claim 2, wherein the optical element is electrically connected to an electric substrate or a semiconductor element via a protruding electrode provided on the optical element and a through-hole electrode formed on the support substrate. .   3. The WDM module according to claim 2, wherein the optical element is embedded in a clad constituting the optical waveguide of the filter built-in type optical waveguide.   5. The WDM module according to claim 4, wherein the optical element is electrically connected to an electric substrate or a semiconductor element via an electrode provided on the optical element and protruding outside the cladding.   6. An optical integrated circuit comprising: an optical I / O port of each semiconductor chip and an optical wiring connecting the optical I / O ports of each semiconductor chip by the WDM module according to claim 1. A method for producing an optical waveguide with a built-in filter in the WDM module according to any one of claims 1 to 5,
An optical waveguide formed with a plurality of slits for multiplexing / demultiplexing filters is fixed to a stage provided at a predetermined angle,
Vacuum chuck multiple multiplexing / demultiplexing filters to the probe,
A method of inserting and bonding each multiplexing / demultiplexing filter into a corresponding slit. A method for producing the WDM module according to claim 3 , comprising:
An optical element having a protruding electrode is pasted on an optical waveguide having a built-in multiplexing / demultiplexing filter built-in,
Coating the support substrate constituting the optical waveguide so as to cover the optical element and support the clad of the optical waveguide;
Form a through-hole electrode on the support substrate,
A method comprising mounting an optical waveguide having an optical element having the protruding electrode and a support substrate having a through hole on an electric substrate or a semiconductor element.   The method of claim 8, wherein the support substrate is coated with the same material as the cladding.

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