JP2006184756A - Optical waveguide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide for controlling the depth of a groove part when forming the groove part in a waveguide layer. <P>SOLUTION: The optical waveguide 1 comprises the waveguide layer 2 multi-layered by laminating a first waveguide layer 2a and a second waveguide layer 2b, and a mounting substrate 3 for supporting the waveguide layer 2. The first waveguide layer 2a forms an insertion groove 7 and is adhered and fixed by inserting a wavelength selection filter 8. A metal layer 10 is formed between the first waveguide layer 2a and the second waveguide layer 2b and used as an etching stopper layer when forming the insertion groove 7 by etching. In addition, the metal layer 10 is used as a reflection layer of light when adhering the wavelength selection filter 8 by an optical curing adhesive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide including a waveguide layer having a core and a clad, and having a groove portion into which an optical component is inserted in the waveguide layer. Specifically, by providing a metal layer on the lower surface of the waveguide layer, when the groove is formed by etching, the etching stops at the metal layer so that the depth of the groove to be processed can be controlled. .

  Conventionally, information transmission between boards in electronic devices, between chips, etc. has been performed by electrical signals, but optical wiring technology has attracted attention in order to realize ultra high speed, large capacity information transmission, A waveguide-type optical module has been proposed that can perform wavelength-division bidirectional optical transmission using optical wiring technology.

  In order to realize wavelength division multiplexing bidirectional optical transmission, it is necessary to have a function of separating and multiplexing optical signals of different wavelengths. For example, wavelength selection having a function of selectively reflecting and transmitting light in an arbitrary wavelength region An optical module using a filter has been proposed.

  In the case of mounting an optical component such as a wavelength selection filter on an optical waveguide, conventionally, a groove is formed in the optical waveguide by dicing, and the optical component is inserted into the groove and bonded and fixed (see, for example, Patent Document 1). .

Japanese Patent Laid-Open No. 11-109149

  However, when forming a groove portion by dicing in the optical waveguide, it is difficult to control the depth of the groove portion to be processed if the optical waveguide is a film-like thin one. As a result, the groove portion is surely formed.

  For this reason, for example, when the waveguide layers are stacked to make the cores multilayer, groove portions are formed in the cores of all layers, and optical components are inserted.

  In addition, when forming a groove portion by dicing, cutting cannot be started from the middle of the optical waveguide, or cutting cannot be stopped halfway, so a continuous groove portion from one end of the optical waveguide to the other end Need to form. Therefore, there are many restrictions on the shape of the optical waveguide, and there is a problem that the degree of freedom in design is low.

  Although it is conceivable to form the groove by etching, there is a problem that it is difficult to control the depth of the groove to be processed.

  Further, when an optical component such as a wavelength selection filter is inserted into the groove formed in the optical waveguide and is fixed by adhesion, a photo-curing type adhesive is often used so as not to be affected by heat. However, since the light is shielded by the substrate or the like, the adhesive cannot be uniformly cured, and there is a problem that the adhesive strength is insufficient.

  The present invention has been made to solve such a problem. When forming a groove in a waveguide layer, the depth of the groove can be controlled, and an optical component inserted into the groove can be bonded. An object of the present invention is to provide an optical waveguide that can be fixed securely.

  In order to solve the above-described problems, an optical waveguide according to the present invention includes a waveguide layer having a core and a cladding, and an optical waveguide in which a groove portion into which an optical component is inserted is formed in the waveguide layer. The lower surface is provided with a metal layer that reflects light in a non-contact manner with respect to the etching for forming the groove.

  In the optical waveguide according to the present invention, when the groove is formed by etching, the etching stops at the metal layer, so that the depth of the groove to be processed is controlled by the position where the metal layer is formed.

  Further, when an optical component inserted into the groove is bonded and fixed, if a photo-curing adhesive is used, a part of the irradiated light is reflected by the metal layer to irradiate the bonded portion. Thereby, an adhesive agent is hardened | cured uniformly.

  According to the optical waveguide of the present invention, the depth of the groove to be processed is accurately controlled by providing a metal layer in the waveguide layer and using it as an etching stopper layer when forming the groove in the waveguide layer. be able to.

  As a result, even in an optical waveguide or the like in which the core is formed in multiple layers, it is possible to accurately separate and process the layer that forms the groove and the layer that does not form the groove. Restrictions and restrictions on the arrangement of cores are relaxed, and design freedom increases.

  In addition, the metal layer can be used as a light reflecting layer for uniformly curing the photo-curing adhesive when the optical component inserted in the groove is bonded and fixed. By hardening to the optical component, it is possible to reliably mount the optical component.

  Hereinafter, embodiments of the optical waveguide of the present invention will be described with reference to the drawings.

<Configuration of optical waveguide>
FIG. 1 is a perspective view showing an example of the configuration of the optical waveguide according to the present embodiment, and FIG. 2 is a cross-sectional view of the vicinity of an insertion groove showing the main configuration of the optical waveguide. The optical waveguide 1 according to the present embodiment includes a waveguide layer 2 in which a first waveguide layer 2 a and a second waveguide layer 2 b are stacked to form a multilayer, and a mounting substrate 3 that supports the waveguide layer 2. . The mounting substrate 3 is, for example, a silicon (Si) substrate, and the waveguide layer 2 is mounted on the surface.

  The first waveguide layer 2a and the second waveguide layer 2b are made of, for example, a polymer material, and include a core 4 and a lower clad 5a and an upper clad 5b that constitute the clad layer 5 to form a core-clad structure. It is an embedded type waveguide. The core 4 is configured such that the refractive index is slightly larger than that of the lower cladding 5a and the upper cladding 5b, and light is confined in the core 4 and propagated.

  The core 4 of the first waveguide layer 2a has, for example, a substantially Y-shaped pattern in which two cores 4a and 4b intersect, and one end of the core 4a is formed at one end of the first waveguide layer 2a. For example, the incident port 6a is configured.

  In addition, one end face of the core 4b is exposed at one end of the first waveguide layer 2a to form, for example, an emission port 6b. Furthermore, the other end face of the core 4a is exposed at the other end portion of the first waveguide layer 2a to constitute, for example, an emission port 6c.

  In the core 4 of the second waveguide layer 2b, for example, one core 4d extends linearly from one end of the second waveguide layer 2b to the other end of the second waveguide layer 2b. Then, one end face of the core 4d is exposed at one end portion of the second waveguide layer 2b to constitute, for example, an incident port 6d. In addition, the other end face (not shown) of the core 4d is exposed at the other end of the second waveguide layer 2b to form, for example, an output port.

  The first waveguide layer 2a includes an insertion groove 7 at the intersection between the core 4a and the core 4b. The insertion groove 7 has an opening on the upper surface of the first waveguide layer 2a, and is formed by, for example, dry etching.

  The insertion groove 7 extends in a direction crossing the intersection of the core 4a and the core 4b. The end face of the core 4a divided by the insertion groove 7 is exposed on one of the opposing side wall surfaces of the insertion groove 7, and the other is The end face of the portion where the core 4a and the core 4b intersect is exposed.

  The wavelength selection filter 8 is inserted into the insertion groove 7 and is bonded and fixed to the first waveguide layer 2 a by the adhesive 9. Here, an adhesive 9 having a refractive index equivalent to that of the core 4 is used.

  The wavelength selection filter 8 constitutes an optical component and has a function of selectively reflecting and transmitting light in an arbitrary wavelength region. For example, the wavelength selective filter 8 is configured to transmit light having a wavelength λ1 and reflect light having a wavelength λ2. Is done.

  The waveguide layer 2 includes a metal layer 10 between the first waveguide layer 2a and the second waveguide layer 2b. For example, the metal layer 10 is formed on the entire surface between the first waveguide layer 2a and the second waveguide layer 2b.

<Manufacturing process of optical waveguide>
3 and 4 are explanatory views showing the manufacturing process of the optical waveguide. Next, the manufacturing process of the optical waveguide 1 will be described.

  First, as shown in FIG. 3A, polymer materials having different refractive indexes are sequentially laminated on a silicon substrate 3a constituting the mounting substrate 3, and a lower clad 5a and an upper clad 5b, and a core 4 having a predetermined pattern. The 2nd waveguide layer 2b which has is produced.

  Next, the metal layer 10 is formed on the second waveguide layer 2b. Here, for example, when an optical waveguide is formed on a silicon wafer, the metal layer 10 is formed on the entire surface of the wafer-like silicon substrate 3a by vapor deposition or the like. The metal layer 10 can be partially formed by a patterning process. The formation position of the metal layer 10 in this case corresponds to the formation position of the insertion groove 7 described with reference to FIGS.

  The metal layer 10 is made of a material that is not touched by an etching process to be described later. For example, Au (gold), Al (aluminum), Ti (titanium), Pt (platinum), Ag (silver), Ni (nickel), And a mixed metal containing these materials.

  Next, polymer materials having different refractive indexes are sequentially laminated on the metal layer 10 to produce a first waveguide layer 2a having a lower clad 5a, an upper clad 5b, and a core 4 having a predetermined pattern.

  Next, as shown in FIG. 3B, the insertion groove 7 is formed in the first waveguide layer 2a. The insertion groove 7 is formed by dry etching such as RIE (Reactive Ion Etching) or wet etching. Here, since the non-etched metal layer 10 is inserted between the first waveguide layer 2a and the second waveguide layer 2b with respect to the etching, the metal layer 10 functions as an etching stopper layer.

  Thereby, the groove depth can be accurately controlled. Specifically, the insertion groove 7 can be formed with the same depth as the thickness of the first waveguide layer 2a. Since the etching stops at the metal layer 10, no groove is formed in the second waveguide layer 2b. Therefore, the core 4 of the second waveguide layer 2b can be arranged immediately below the insertion groove 7.

  Now, the thickness of the first waveguide layer 2a and the second waveguide layer 2b is, for example, about 100 μm. Since the insertion groove 7 has the same depth as the thickness of the first waveguide layer 2a, the insertion groove 7 is not deep enough to hold the wavelength selective filter 8 vertically when the wavelength selective filter 8 is mounted. .

  Therefore, as shown in FIG. 4A, the wavelength selection filter 8 is supported by a filter fixing jig 11 that maintains verticality, and is bonded and fixed to the first waveguide layer 2a. In this example, the wavelength selective filter 8 is inserted into the insertion groove 7, and the adhesive 9 is applied in a state where the wavelength selective filter 8 is held vertically by the filter fixing jig 11. As the adhesive 9, for example, an ultraviolet (UV) curable adhesive is used, and as shown in FIG. 4B, ultraviolet rays are irradiated obliquely from above so as to avoid the filter fixing jig 11.

  Part of the ultraviolet rays irradiated obliquely from above directly irradiates the adhesive 9 to cure the adhesive 9. Further, a part of the light is reflected by the metal layer 10, so that the adhesive 9 is irradiated indirectly to cure the adhesive 9. Thereby, the adhesive 9 of the part shielded with the filter fixing jig 11 etc. can also be hardened.

  Finally, when the filter fixing jig 11 is removed, the optical waveguide 1 on which the wavelength selection filter 8 is mounted is completed as shown in FIGS. As described above, the wavelength selection filter 8 is mounted using the filter fixing jig 11 and is fixed while maintaining verticality.

  In addition, when the light for curing the adhesive 9 is irradiated, the light can be reflected indirectly by the metal layer 10 so that the bonded portion can be indirectly irradiated. Therefore, the light cannot be directly irradiated by being shielded by the filter fixing jig 11 or the like. Also, the adhesive 9 can be cured by irradiating light. Thereby, the wavelength selection filter 8 can be reliably fixed.

  In the above example, the waveguide layer has been described as an example having two layers, but three or more layers may be used. Further, even if the waveguide layer is one layer, the effect of the present invention can be obtained. Furthermore, as an optical component that forms a groove in the optical waveguide 1 and is bonded and fixed, in addition to the wavelength selection filter, an optical fiber or the like may be used.

  That is, a groove is formed in the end face where the core 4 of the optical waveguide 1 is exposed, and an optical fiber is inserted and fixed in the groove, so that the core 4 and the optical fiber can be optically coupled and connected. .

  Even when forming a groove portion for inserting and fixing such an optical fiber, a groove having a predetermined depth can be formed by using the metal layer 10, and reflection on the metal layer 10 can be used. Thus, the adhesive can be uniformly cured.

<Operation of optical waveguide>
Next, the operation of the optical waveguide 1 will be described. For example, the light of wavelength λ1 that has entered from the incident port 6a of the first waveguide layer 2a is propagated through the core 4a and enters the wavelength selection filter 8. Since the wavelength selective filter 8 transmits light of wavelength λ1 in this example, the light of wavelength λ1 incident from the incident port 6a passes through the wavelength selective filter 8 and enters the core 4a at the tip of the insertion groove 7. Further, it is propagated through the core 4a. The light propagated through the core 4a is emitted from the emission port 6c.

  On the other hand, the light having the wavelength λ2 incident from the incident port 6a is propagated through the core 4a and enters the wavelength selection filter 8. In this example, the wavelength selective filter 8 reflects the light with the wavelength λ2, so that the light with the wavelength λ2 incident from the incident port 6a is reflected by the wavelength selective filter 8 and enters the core 4b, and propagates through the core 4b. . The light propagated through the core 4b is emitted from the emission port 6b.

  Further, light incident from the incident port 6d of the second waveguide layer 2b is propagated through the core 4d. Since the core 4d of the second waveguide layer 2b and the cores 4a and 4b of the first waveguide layer 2a are independent, the insertion groove 7 does not reach the second waveguide layer 2b. The light propagated through the core 4d of the second waveguide layer 2b is output from an output port (not shown) without being reflected or transmitted by the wavelength selection filter 8.

  As described above, since the wavelength selection filter 8 is well maintained with respect to the cores 4a and 4b, loss at the optical coupling portion between the wavelength selection filter 8 and the core 4 can be suppressed. Thereby, the optical waveguide 1 functions as a low-loss wavelength multiplexer / demultiplexer.

  Moreover, since the core 4d of the second waveguide layer 2b and the cores 4a and 4b of the first waveguide layer 2a are independent, the optical waveguide 1 can transmit and receive three types of signals.

  The present invention is applied to an optical communication module between boards or chips of an electronic device, a connector of a communication cable using an optical fiber, and the like.

It is a perspective view which shows an example of a structure of the optical waveguide of this Embodiment. It is sectional drawing of the insertion groove vicinity which shows the principal part structure of an optical waveguide. It is explanatory drawing which shows the manufacturing process of an optical waveguide. It is explanatory drawing which shows the manufacturing process of an optical waveguide.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical waveguide, 2 ... Waveguide layer, 3 ... Mounting board, 4 ... Core, 5 ... Cladding layer, 6a ... Incident port, 6b ... Outlet port, 6c ... Exit port, 7 ... insertion groove, 8 ... wavelength selection filter, 9 ... adhesive, 10 ... metal layer

Claims (5)

In an optical waveguide comprising a waveguide layer having a core and a cladding, and having a groove portion into which an optical component is inserted in the waveguide layer,
An optical waveguide, comprising: a metal layer that is non-contact with the etching for forming the groove and reflects light on a lower surface of the waveguide layer. 2. The optical waveguide according to claim 1, wherein the waveguide layer is configured in a multilayer including two or more cores, and at least one metal layer is formed between the waveguide layers. The optical waveguide according to claim 1, wherein the metal layer is patterned at a position that is at least a bottom surface of the groove. The optical waveguide according to claim 1, wherein the optical component inserted into the groove is bonded and fixed with a photo-curing adhesive. The optical waveguide according to claim 1, wherein the metal layer is Au, Al, Ti, Pt, Ag, Ni, or a mixed metal containing these materials.

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