Optical module and component thereof

Abstract

The present disclosure provides: an optical device-use component for easily bonding and fixing a tube at a suitable position; and an optical module having the component. A component, which is used for a connection section between a silicon chip (23) and an optical fiber (20) that are integrated on a device substrate (10), includes: a flat plate-like upper section (31a); and a first lateral-section (31b) and a second lateral-section (31c) that are substantially perpendicular to the upper section (31a). The component also has a recess formed by the upper section (31a), the first lateral-section (31b), and the second lateral-section (31c), and accommodating a fiber block (21) for holding the optical fiber (20). The recess has an opening allowing the optical fiber (20) to be drawn in an extension direction with respect to the second lateral-section (31c). Furthermore, the component has a pressed part (50) formed on the upper section (31a) and substantially perpendicular to the upper section (31a). The pressed section (50) is configured so that an end of a tube (22) having a hollow section through which the optical fiber (20) passes abuts the pressed section.

Description

Optical modules and their components

[0001] The present disclosure relates to an optical module, and more particularly to a component used in a connection between an optical device and an optical fiber, and an optical module including the component.

[0002] Optical transmitter / receiver modules in networks have traditionally been required to be smaller, consume less power, and have higher transmission speeds. Coherent optical subassemblies (COSAs), which integrate optical transmitter and receiver circuits on a small silicon chip and package them together with amplifiers and other electronic circuits, are expected to be a device that can achieve these goals.

[0003] Fig. 1 shows a conventional COSA 100. Fig. 1(a) is a perspective view from above, Fig. 1(b) is a perspective view from below, Fig. 1(c) is a perspective view from below of the input / output section of the COSA 100, and Fig. 1(d) is a cross-sectional view of the input / output section of the COSA 100 taken along the section line Id-Id. The BGA (ball grid array) side of the device substrate 10 constituting the COSA 100 is referred to as the bottom surface.

[0004] As shown in Fig. 1, the COSA 100 includes a device substrate 10 on which a silicon chip 23 including a waveguide utilizing silicon photonics technology is integrated, and a lid 30 that protects them. Fig. 1 also shows an optical fiber 20 that is optically connected to the waveguide formed on the surface of the silicon chip 23. The silicon chip 23 is integrated so that the surface on which the waveguide is formed faces the underside of the device substrate 10.

[0005] The fiber block 21 is directly fixed to the silicon chip 23 so that the optical fibers 20 connect to the waveguides of the silicon chip 23 via the fiber block 21. As shown in FIG. 1( d ), the fiber block 21 does not come into contact with the lid 30, with a small gap between them. In FIG. 1 , the optical fibers 20 represent a ribbon core wire in which multiple optical fibers are aligned. The tips of the core wires of the optical fibers 20 are aligned along a V-groove in the fiber block 21. FIG. 1 also shows a fiber protection resin 24 arranged opposite the V-groove in the fiber block 21. The optical fibers 20 are fixed between the V-groove and the fiber protection resin 24. The tips of the core wires extend through the V-groove to the end face of the fiber block 21. The end face of the silicon chip 23 and the end face of the fiber block 21 are connected and fixed facing each other. Note that, to prevent reflection at the end face of the silicon chip 23, the orientation of the waveguides near the end face of the silicon chip 23 is not perpendicular to the end face (not in the X direction). The extending direction of the optical fiber 20 is also not perpendicular to the end face of the silicon chip 23 .

[0006] The lid 30 shown in FIG. 1 has an optical fiber coupling portion protection portion 31 for protecting the coupling portion between the optical fiber 20 and the waveguide formed on the surface of the silicon chip 23 .

[0007] Fig. 2 shows a conventional optical fiber coupling protection part 31. Fig. 2(a) is a perspective view from the bottom of the input / output part of the COSA 100 similar to Fig. 1(c), Fig. 2(b) is a cross-sectional view in the extension direction of the optical fiber 20 taken along the cross-sectional line IIb-IIb, Fig. 2(c) is a plan view from the bottom of a portion of the optical fiber coupling protection part 31, and Fig. 2(d) is a cross-sectional view of a portion of the optical fiber coupling protection part 31 taken along the cross-sectional line IId-IId.

[0008] The optical fiber coupling protection part 31 has a flat upper part 31a and side parts 31b and 31c that are approximately perpendicular to the upper part 31a in three directions around the fiber block. As shown in Fig. 2(a) , the fiber block 21 is housed in the space formed by the upper part 31a, the side parts 31b and 31c. The side part 31c has an opening for passing the optical fiber 20 through.

[0009] The optical fiber 20 is weak against a force perpendicular to the drawing direction. Therefore, as shown in Figure 2, a tube 22 is provided to protect the optical fiber 20 so that the optical fiber 20 does not come into direct contact with the opening. The optical fiber 20 passes through the tube 22 and is fixed to the fiber block 21.

[0010] The inner diameter of the tube 22 is sufficiently larger than the sum of the diameters of the individual core wires of the optical fiber 20. Therefore, the tube 22 is freely movable in the extending direction of the optical fiber 20. For this reason, the tube 22 is fixed to the optical fiber coupling portion protection portion 31 so as not to move.

[0011] 3 is a cross-sectional view of the opening in the side portion 31c taken along the line III-III in FIG. 2(a). The opening has an upper portion 32a and a side portion 32b. The tube 22 is disposed to pass through the opening and is bonded and fixed with adhesive 40 inserted between the tube 22 and the opening.

[0012] FIG. 4 is an enlarged bottom view of the opening in the side portion 31c of the optical fiber coupling protection portion 31. The adhesive 40 used to bond and secure the tube 22 to the opening is injected in the order of (1) to (4) in FIG. 4. First, fluid adhesive 40 is injected between the side portion 32b and the tube 22 from the tip of the triangle indicated by (1) and (2), temporarily securing the tube 22 in the state shown in FIG. 3. Next, additional adhesive 40 is injected from the tip of the triangle indicated by (3) and (4), forming fillets 40a and 40b on the top of the tube 22 and outside the opening. The dashed-line rectangle in FIG. 4 indicates the fillet 40a on the opposite side of the top portion 32a of the tube 22, and the dashed-dotted trapezoid indicates the fillet 40b on the outside of the opening in the side portion 31c (32b) of the tube 22. The optical fiber 20 extends through the inside (hollow portion) of the tube 22 from the outside to the inside of the opening in the side portion 31c. The portion of the optical fiber 20 from which the coating has been removed and which protrudes from the hollow portion of the tube 22 (the bare core wire located from the outside to the inside of the opening of the side portion 31c) is fixed in a sandwiched state between the V-groove of the fiber block 21 and the fiber protection resin 24.

[0013] In fabricating an optical module, the process of positioning the tip of the tube 22 on the fiber block 21 side and fixing it in the opening is an important process. If the distance between the fiber block 21 and the tip of the tube 22 is too short, the optical fiber coupling section protector 31 will expand and contract due to the heat generated in the subsequent reflow process, causing the tip of the tube 22 to move and exert pressure on the fiber block 21. As a result, there is a high possibility of coupling loss occurring between the optical fiber 20 and the waveguide formed on the surface of the silicon chip 23. Conversely, if the distance between the fiber block 21 and the tip of the tube 22 is too long, for example, when the tip of the tube 22 is located within the opening, the tube 22 may not be sufficiently fixed by the adhesive 40, resulting in reduced reliability. Furthermore, if the adhesive 40 adheres to the exposed optical fiber 20 between the fiber block 21 and the tube 22, or if the adhesive 40 flows into the hollow portion of the tube 22 and bonds and fixes the tube 22 to the optical fiber 20, the optical fiber 20 may be damaged by the stress of expansion and contraction of the optical fiber coupling section protector 31 generated in the subsequent reflow process.

[0014] To prevent this, it is necessary to position the tip of the tube 22, which has a predetermined length, at a predetermined position. For example, it is necessary to confirm whether the distance between one tip of the tube 22, which has a predetermined length (e.g., 3.6±0.3 mm), and the fiber block 21 is within a predetermined range (e.g., 0.25 mm to 0.5 mm). At the same time, it is also necessary to confirm whether the other tip of the tube 22 is within a predetermined range (e.g., 2 mm or less) outside the opening of the side portion 31 c of the optical fiber coupling portion protection portion 31.

[0015] Therefore, the process of positioning the tip of the tube 22 on the fiber block 21 side and the process of fixing the tube 22 to the opening of the optical fiber coupling portion protection portion 31 with adhesive 40 required delicate work under a microscope, which was extremely inefficient.

[0016] The present disclosure has been made in consideration of such problems, and its purpose is to provide a component for an optical device that allows a tube to be easily adhesively fixed in an appropriate position, and an optical module equipped with the component.

[0017] A component according to an embodiment of the present disclosure is a component used for connecting an optical fiber to a silicon chip integrated on an optical device substrate, and includes a flat upper portion, first and second side portions substantially perpendicular to the upper portion, a recess formed by the upper portion, the first and second side portions, and a pressing portion formed at a predetermined position on the upper portion within the recess and substantially perpendicular to the upper portion.

[0018] In one embodiment, the component further includes a tube having a hollow portion through which the optical fiber placed in the opening of the second side passes, and the pressing portion is formed at a position where a portion of the tube abuts but does not come into contact with the optical fiber.

[0019] In one embodiment, the pressing portion is formed to abut against a part of the tube at one location.

[0020] In one embodiment, the pressing portion is formed to abut against a part of the tube at two locations.

[0021] In one embodiment, the pressing portion that comes into contact with a part of the tube at two locations is connected at the upper side.

[0022] The component according to one embodiment further includes an adhesive receiving portion formed between the pressing portion and the opening.

[0023] In one embodiment of the component, the adhesive containing portion is formed by cutting further than the surface on which the pressing portion is formed.

[0024] An optical module according to one embodiment of the present disclosure includes any of the above-described components, an optical device substrate, and a waveguide formed on the surface of a silicon chip, and the waveguide and an optical fiber are optically coupled at the end face of the silicon chip.

[0025] As described above, according to one embodiment of the present disclosure, the pressing portion of the optical device component can easily adhesively fix a tube to a predetermined position of the optical device component. Also, it becomes possible to efficiently manufacture an optical module including an optical device component having the pressing portion.

[0026] 2A and 2B are diagrams showing a conventional digital coherent optical module (Coherent Optical SubAssembly: COSA), where (a) is a perspective view from above, (b) is a perspective view from below, (c) is a perspective view from below of the input / output section of the COSA, and (d) is a cross-sectional view of the input / output section of the COSA taken along the Id-Id cross-sectional line.

[0024] Fig. 2B is a diagram showing a conventional optical fiber coupling protection section, where (a) is a perspective view from below of the input / output section of the COSA, (b) is a cross-sectional view in the extension direction of the optical fiber taken along the IIb-IIb cross-sectional line, (c) is a plan view of a portion of the optical fiber coupling protection section taken along the bottom cross-sectional line, and (d) is a cross-sectional view of a portion of the optical fiber coupling protection section taken along the IId-IId cross-sectional line.

[0025] Fig. 2B is a cross-sectional view of a side opening of the conventional optical fiber coupling protection section taken along the III-III cross-sectional line of Fig. 2A. Fig. 2C is an enlarged top view of the side opening of the conventional optical fiber coupling protection section.

[0023] Figures 1A and 1B show an optical fiber coupling protection unit of an optical module (COSA) according to an embodiment of the present disclosure, where (a) is a perspective view from below of an input / output unit of the COSA, (b) is a cross-sectional view in the direction of extension of the optical fiber taken along the Vb-Vb cross-section line, (c) is a plan view from below of a portion of the optical fiber coupling protection unit, and (d) is a cross-sectional view from below of a portion of the optical fiber coupling protection unit taken along the Vd-Vd cross-section line. Figures 1A and 1B show a first example of a pressing unit of the optical fiber coupling protection unit of the COSA according to an embodiment of the present disclosure, where (a) is a plan view from below, (b) is a cross-sectional view from the VIb-VIb cross-section line, and (c) is a cross-sectional view from the VIc-VIc cross-section line. Figures 1B and 1C show a second example of a pressing unit of the optical fiber coupling protection unit of the COSA according to an embodiment of the present disclosure, where (a) is a plan view from below, (b) is a cross-sectional view from the VIIb-VIIb cross-section line, and (c) is a cross-sectional view from the VIIc-VIIc cross-section line. 8A to 8C are diagrams showing a third example of a pressing portion of an optical fiber coupling portion protection portion of a COSA according to an embodiment of the present disclosure, in which (a) is a plan view from the bottom, (b) is a cross-sectional view, and (c) is a cross-sectional view taken along the VIIIc-VIIIc cross-sectional line.

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or similar reference numerals indicate the same or similar elements, and repeated description may be omitted. Materials and values ​​in the following description are exemplary, and other materials and values ​​may be used to implement the present disclosure. Hereinafter, a digital coherent optical module (COSA) will be exemplified as an optical device. It goes without saying that the present disclosure can be implemented in any optical device other than a COSA without departing from the spirit and scope of the present disclosure. In the following description, the lid 30 side of the optical module 100 will be referred to as the upper direction and the device substrate 10 side as the lower direction.

[0028] 5 is a diagram showing an optical fiber coupling section protector 31 of a COSA according to an embodiment of the present disclosure. The optical fiber coupling section protector 31 constitutes a part of the lid 30 described with reference to FIG. 1. As described above, the optical fiber coupling section protector 31 is a component for an optical device that protects the coupling section between the optical fiber 20 and the waveguide formed on the surface of the silicon chip 23. The optical fiber coupling section protector 31 may be formed integrally with the lid 30 that protects the device substrate 10 on which the silicon chip 23 is integrated, or may be formed separately.

[0029] The protective lid 30 can be formed by machining a metal plate. When the lid 30 and the optical fiber coupling portion protection portion 31 are formed separately, if the lid 30 is made of metal, the material for the optical fiber coupling portion protection portion 31 can also be ceramic or resin. In consideration of heat dissipation from the device substrate 10 on which the silicon chip 23 is integrated, the lid 30 is preferably made of a metal with high thermal conductivity. In this embodiment, the optical fiber coupling portion protection portion 31 is formed integrally with the lid 30 by machining a metal plate.

[0030] Like the conventional optical fiber coupling protection part 31, the optical fiber coupling protection part 31 of this embodiment also has a flat upper part 31a and side parts 31b and 31c that are substantially perpendicular to the upper part 31a and surround the fiber block. As shown in FIG. 5( a), the fiber block 21 is housed in a space (recess) formed by the upper part 31a, the side parts 31b, and the side parts 31c. The fiber block 21 does not contact the upper part 31a, and there is a gap between them. The side part 31c has an opening. The opening has an opening approximately the same diameter as the tube 22. In FIG. 5( d), the opening where the tube 22 is housed has a rectangular shape when viewed from the extension direction of the optical fiber 20, but it may also have a U-shape. Furthermore, the side wall of the opening facing the tube 22 may be a surface parallel to the extension direction of the optical fiber 20 or may have a shape that widens from the inside to the outside. In the latter case, the injected adhesive 40 is more effectively prevented from leaking to the upper part 31a.

[0031] As shown in FIG. 5, the optical fiber coupling protection part 31 of this embodiment differs from the conventional optical fiber coupling protection part 31 shown in FIG. 2 in that a pressing part 50 is formed substantially perpendicular to the upper part 31 a near the side part 31 c having an opening.

[0032] The pressing portion 50 is formed so that the end of the tube 22 is positioned in a predetermined position (i.e., an appropriate position for the end of the tube 22). The tube 22 is inserted into the side portion 31c from the outside through the opening, and the tube 22 is fixed in place when at least a portion of the tube 22 abuts against the pressing portion 50. When the end of the tube 22 abuts against the pressing portion 50, one end of the tube 22 is located inside the optical fiber coupling protection portion 31 relative to the opening of the side portion 31c, and the other end is located outside the side portion 31c. This eliminates the need for delicate positioning under a microscope, and allows for easy, highly accurate positioning in a short time. By adhering the tube 22 to the opening of the side portion 31c in this state with the adhesive 40, the tube 22 is fixed across the entire thickness of the opening, thereby solving the problem of reduced reliability caused by insufficient adhesive fixation.

[0033] Excess adhesive when bonding the tube 22 falls onto the upper part 31a between the opening and the pressing part 50. If the fallen adhesive seeps into the gap between the fiber block 21 and the upper part 31a and fixes the fiber block 21 to the upper part 31a, expansion of the lid 30 during the reflow process will apply force to the joint between the fiber block 21 and the silicon chip 23, which could cause misalignment of the optical axis or a deterioration in the fixing strength of the fiber block 21. Therefore, it is desirable to prevent the fallen excess adhesive from seeping into the fiber block 21 side.

[0034] In this embodiment, when the pressing portion 50 is formed by cutting, both ends of the pressing portion 50 are in contact with the side portion 31c. This forms a closed area (hereinafter, referred to as the adhesive storage portion 51) on the upper portion 31a by the pressing portion 50 and the side portion 31c. As shown in FIG. 5(d), by enclosing the area into which excess adhesive falls with a wall, the spread of the fallen adhesive can be prevented. The adhesive storage portion 51 is formed between the pressing portion 50 and the opening of the side portion 31c. The outer wall of the adhesive storage portion 51 includes at least the pressing portion 50 and the side portion 31c in the area where the opening is formed. In other words, the opening-side portion of the pressing portion 50 and the opposing opening portion of the side portion 31c constitute part of the adhesive storage portion 51. In FIG. 5(d), the pressing portion 50 is formed to surround the opening, and both ends thereof are in contact with parts of the side portion 31c. In other words, when the adhesive containing portion 51 is produced by cutting, a part of the side wall of the adhesive containing portion 51 is used as the pressing portion 50 .

[0035] From the viewpoint of preventing the dropped adhesive from spreading over the upper portion 31a and entering the gap between the fiber block 21 and the upper portion 31a, a groove may be formed by cutting deeper between the pressing portion 50 and the region where the opening is formed (reducing the thickness from the back surface of the upper portion 31a), and the groove may become at least a part of the adhesive containing portion 51. The groove will be described later.

[0036] The structure of the adhesive storage section 51 can be exemplified as follows: The thickness H1 of the opening of the side section 31c (thickness from the back surface of the upper section 31a to the bottom surface of the opening) is 0.9 mm. The thickness H2 of the adhesive storage section 51 of the side section 31c (thickness from the back surface of the upper section 31a to the bottom surface of the adhesive storage section 51) is 0.6 mm. The thickness H3 of the pressing section 50 (thickness from the back surface of the upper section 31a to the tip of the pressing section 50) is 1.15 mm. The thickness H4 of the recess of the side section 31c (thickness from the bottom surface of the side section 31c to the bottom surface of the opening) is 1.05 mm.

[0037] The length of the tube 22 (in the extending direction of the optical fiber 20) is 2.0 mm. The outer diameter of the tube 22 is 0.9 mm. The inner diameter of the tube 22 is 0.82 mm. The thickness of the tube 22 is 0.04 mm. The width of the opening in the side portion 31c is 1.2 mm. The distance between the tube 22 and the opening is 0.15 mm.

[0038] The length L1 of the opening of the side portion 31c (in the extension direction of the optical fiber 20) is 1.75 mm. The distance L2 between the opening side of the pressing portion 50 and the opening of the side portion 31c (the distance between the adhesive containing portion 51 in the extension direction of the optical fiber 20) is 0.6 mm. The length L3 of the pressing portion 50 (in the extension direction of the optical fiber 20) is 0.2 to 0.3 mm. The distance L4 between the pressing portion 50 and the fiber block 21 is 0.347 mm.

[0039] With the end of the tube 22 in contact with the pressing portion 50, when the adhesive 40 is inserted into the gap between the tube 22 and the side portion 31c in the manner described with reference to Fig. 4, excess adhesive will flow down into the adhesive storage portion 51. Because the optical fiber 20 is covered with the tube 22 up to the pressing portion 50, excess adhesive 40 will fall from both sides of the tube 22 near the opening before reaching the pressing portion 50. This prevents the adhesive 40 from adhering to the exposed optical fiber 20 between the fiber block 21 and the tube 22, or from flowing into the hollow portion of the tube 22 (i.e., the tube 22 and the optical fiber 20 will be bonded by the adhesive 40 in the hollow portion).

[0040] In this way, the optical fiber coupling protection part 31 of this embodiment facilitates the process of positioning the tip of the tube 22 on the fiber block 21 side and the process of fixing the tube 22 to the opening of the side part 31c of the optical fiber coupling protection part 31 with adhesive 40.

[0041] Hereinafter, the optical fiber coupling portion protection portion 31 according to the first to third embodiments will be described with reference to FIGS.

[0042] Example 1 FIG. 6 illustrates an optical fiber coupling protection part 31 of a COSA according to an embodiment of the present disclosure. FIG. 6( a) is a schematic plan view of a portion of the optical fiber coupling protection part 31 as viewed from the underside. FIG. 6( b) is a schematic cross-sectional view of a portion of the optical fiber coupling protection part 31 taken along the VIb-VIb cross-section. FIG. 6( c) is a cross-sectional view taken along the VIc-VIc cross-section. A rectangular pressing part 50 is formed inside the optical fiber coupling protection part 31, spaced from the opening, and generally perpendicular to the upper part 31a. An adhesive accommodating part 51 is formed between the side part 31c and the pressing part 50. The pressing part 50 forms part of the side wall of the adhesive accommodating part 51. As shown in FIG. 6( b), the adhesive accommodating part 51 is cut to be deeper (i.e., thinner from the top surface 31TS of the upper part 31a) than in the example shown in FIG. 5( d). 6, the width W of the rectangular pressing portion 50 is the same as the width of the opening, but it can be narrower than the width of the opening as long as it is abutting against part of the tube 22, but it is better if it is wider than the diameter of the tube 22. This is to prevent excess adhesive that has fallen from the tube 22 from leaking past the pressing portion 50 and spreading toward the fiber block 21. Also, although the center of the width W is positioned so as to coincide with the center of the opening of the optical fiber coupling portion protection portion 31, it is not necessary to position it so as to coincide with the center of the opening as long as it is a position where it will abut against part of the tube 22.

[0043] An example of the positional relationship between the pressing portion 50 and the opening is as follows: The thickness H1 of the opening in the side portion 31c (the thickness from the top surface 31TS of the optical fiber coupling portion protection portion 31 to the position 31cBS of the opening) is 0.9 mm, and the thickness H3 of the pressing portion 50 (the thickness from the top surface 31TS of the optical fiber coupling portion protection portion 31 to the tip 50BS of the pressing portion 50) is 1.15 mm. Therefore, as shown in FIG. 6 , when the tube 22 is inserted into the opening in the side portion 31c, a portion of the end of the tube 22 abuts against the pressing portion 50 and stops. Meanwhile, the inner diameter of the tube 22 is 0.82 mm and the thickness is 0.04 mm, and the optical fiber 20 passes through the inside of the tube 22 opposite the abutment portion, so it can pass through a position sufficiently distant from the tip of the pressing portion 50. If the thickness H3 of the pressing portion 50 is too large, there is a risk that the tip of the pressing portion 50 may come into contact with the optical fiber 20, so it is desirable that the tip of the pressing portion 50 be positioned at a height approximately equal to the center of the tube 22. In this way, the fiber block 21 is fixed to the end face of the silicon chip 23 in an optically coupled state.

[0044] With a portion of the end of the tube 22 abutting against the pressing portion 50, the tube 22 is temporarily fixed to the opening of the optical fiber coupling portion protection portion 31 using adhesive 40 as described with reference to FIG. 4 , and then fillets 40a and 40b are formed. The end of the tube 22 abutting against the pressing portion 50 is in a predetermined appropriate position (i.e., a position that prevents adhesion of adhesive 40), so positioning under a microscope is not required. Furthermore, when the tube 22 abuts against the pressing portion 50, the length of the tube 22 from the opening to the pressing portion 50 is sufficient, so excess adhesive 40 flows down from both sides of the tube 22 into the adhesive storage portion 51 near the opening without reaching the pressing portion 50, preventing the adhesive 40 from adhering to the optical fiber 20. While the pressing portion 50 in Example 1 has a wide, low-profile rectangular shape on a surface perpendicular to the extension direction of the optical fiber 20, other shapes may also be used, as exemplified below.

[0045] Example 2 With reference to Figure 7, a description will be given of a narrow, tall, rectangular pressing portion 50a in a plane perpendicular to the extension direction of the optical fiber 20. While the configuration of Example 1 in Figure 6 has one pressing portion 50, the configuration of Example 2 differs from the configuration of Example 1 in that it has two columnar pressing portions 50a. Figure 7 is a diagram showing an optical fiber coupling portion protection portion 31 of a COSA according to an embodiment of the present disclosure. Figure 7(a) is a schematic plan view of the underside of a portion of the optical fiber coupling portion protection portion 31. Figure 7(b) is a cross-sectional view of a portion of the optical fiber coupling portion protection portion 31 taken along the VIIb-VIIb cross-section line. Figure 7(c) is a cross-sectional view taken along the VIIc-VIIc cross-section line.

[0046] 7, the two pressing portions 50a are formed substantially perpendicularly on the upper portion 31a of the optical fiber coupling portion protection portion 31 at positions on the device substrate 10 (not shown) side, spaced apart from the side portion 31c having the opening of the optical fiber coupling portion protection portion 31. In this Example 2, an adhesive storage portion 51 is formed in the upper portion 31a by cutting out a portion between the pressing portions 50a, including an area into which excess adhesive falls, and the opening. In this Example 2, the two pillar-shaped pressing portions 50a are connected by a portion cut into a rectangular flat plate, which forms part of the side wall of the adhesive storage portion 51.

[0047] The spacing between the pressing portions 50a on the two columns is such that portions of the two pressing portions 50a abut on both horizontal ends of the cross section of the tube 22. Because the abutting portions of the two pressing portions 50a are formed at the same distance from the opening, the tube 22, abutting at two points, is positioned parallel to the optical fiber 20. Pressing the tube 22 at two points prevents the tube 22 from tilting, which has the advantage of allowing the tube 22 to be positioned parallel to the optical fiber 20. This prevents contact between the tube 22 and the optical fiber 20. The two pressing portions 50a have the same width Wa, but may have different widths. Furthermore, the two pressing portions 50a are positioned so that the center of the gap between the two pressing portions 50a is the center of the opening of the optical fiber coupling protection portion 31. However, as long as a part of the tube 22 is positioned to abut against at least one of the two pressing portions 50a, the center of the gap between the two pressing portions 50a does not have to be the center of the opening of the optical fiber coupling portion protection portion 31. Also, in this second embodiment, a connecting portion is provided between the two pressing portions 50a, but the shape and size of the connecting portion are not limited to a rectangle as long as it does not come into contact with the optical fiber 20. There may be no connecting portion, but if there is a risk of the dropped adhesive spreading, the depth of the adhesive storage portion 51 needs to be increased.

[0048] The tips 50BS of the two pressing portions 50a are located near the lower side of the tube 22 (the side closer to the optical fiber 20), and the lower surface of the connecting portion (the surface not in contact with 31a) has a thickness approximately the same as the opening H1. (An example of the second embodiment is as follows. The thickness H1 of the opening of the side portion 31c (the thickness from the top surface 31TS of the optical fiber coupling portion protection portion 31 to the position 31cBS of the opening) is 0.9 mm, and the thickness H3a from the top surface 31TS to the tip 50aBS of the pressing portion 50a is 1.8 mm. The distance between the two pressing portions 50a is appropriately between the inner diameter and the outer diameter of the tube 22 (approximately 0.82 mm to 0.9 mm). This is because the tube 22 is elliptical in shape and therefore stretches slightly in the left-right direction. Therefore, in the structure of the second embodiment, as shown in FIG. 7, when the tube 22 is inserted into the opening of the side portion 31c, both sides of the tube 22 simultaneously abut against the two pressing portions 50a and are stopped. Meanwhile, the optical fiber 20 inserted into the hollow portion of the tube 22 can pass between the two pressing portions 50a. In this way, optical coupling can be achieved between the end face of the fiber block 21 fixed to the tip of the optical fiber 20 and the end face of the silicon chip 23.

[0049] This second embodiment also has the same effect as the first embodiment, but the adhesive storage section of this second embodiment has the additional advantage that the tube 22 is abutted against two pressing portions 50a, which not only has the advantage of allowing the tube 22 to be positioned parallel to the optical fiber 20 during the abutment process, but also makes it possible to carry out the abutment process more easily, accurately, and reliably than when abutting at one point.

[0050] Example 3 Example 3, which is a modification of Example 2, will be described with reference to Figure 8. Figure 8(a) is a schematic plan view of the underside of a portion of the optical fiber coupling protection portion 31. Figure 8(b) is a cross-sectional view of a portion of the optical fiber coupling protection portion 31 taken along the VIIIb-VIIIb cross-sectional line. Figure 8(c) is a cross-sectional view taken along the VIIIc-VIIIc cross-sectional line. As shown in Figure 8, an L-shaped or hook-shaped pressing portion may also be used. A columnar central portion that is approximately perpendicular to the upper portion 31a may serve as the pressing portion 50a, and a portion that is approximately horizontal to the upper portion 31a may form part of the adhesive containing portion 51.

[0051] (Other Modifications) In Example 1 of FIG. 6 , the tip 50BS of the pressing portion 50 is shown as a rectangle, but the pressing portion 50 may have a shape that surrounds an opening. In this case, the shape is sufficient so that the falling adhesive falls into the adhesive storage portion 51, preventing the falling adhesive from spreading. In Example 1 of FIG. 6 , the width of the pressing portion 50a is made wider than the outer diameter of the tube 22 to prevent the falling adhesive from spreading. As a modification of this example, the width of the pressing portion 50 may be expanded to the side portions 31b to enhance the role of preventing the falling adhesive from spreading. In this case, the expanded portion may have a flat or curved shape, and the angle between the center portion (the portion with width W) and the expanded portion may be between 90 degrees and 180 degrees to prevent the falling adhesive from spreading. Furthermore, as a modification of FIGS. 7 and 8 , the width of the columnar pressing portion 50a may be expanded to the side portions 31b to enhance the role of preventing the falling adhesive from spreading. In this case, the expanding portion may be flat or curved, and the angle between the columnar pressing portion 50a (portion with width Wa) and the expanding portion is between 90 degrees and 180 degrees, so as to prevent the falling adhesive from spreading.

[0052] REFERENCE SIGNS LIST 100 Optical module (COSA) 10 Device substrate 20 Optical fiber 21 Fiber block 22 Tube 23 Silicon chip 24 Fiber protection resin 30 Lid 31 Optical fiber coupling portion protection portion 31a Upper portion 31b Side portion 31c Side portion with opening 32a Upper portion 32b Side portion 40 Adhesive 40a, 40b Fillets 50, 50a Pressing portion 51 Adhesive containing portion

Claims

1. A component used in a connection between a silicon chip integrated on a device substrate and an optical fiber, comprising: a flat upper portion, a first side portion and a second side portion substantially perpendicular to the upper portion; a recess formed by the upper portion, the first side portion, and the second side portion, the second side portion having an opening; and a pressing portion formed on the upper portion within the recess, the pressing portion being substantially perpendicular to the upper portion, and formed in a position facing the opening.

2. The part according to claim 1, wherein the part further comprises a tube having a hollow portion through which the optical fiber placed in the opening passes, and the pressing portion is formed at a position where a part of the tube abuts but does not contact the optical fiber.

3. The part according to claim 2, wherein the pressing portion is formed so as to abut against a portion of the tube at one point.

4. The part according to claim 2, wherein the pressing portion is formed so as to abut against a portion of the tube at two points.

5. The part according to claim 4, wherein the pressing portion that abuts against a part of the tube at the two points is connected at the upper side.

6. The component of claim 2, further comprising an adhesive receiving portion formed between said pressing portion and said opening.

7. The part according to claim 6, wherein the adhesive containing portion is cut and formed further than the surface on which the pressing portion is formed.

8. An optical module comprising: a component according to any one of claims 1 to 7; the device substrate; and a waveguide formed on a surface of the silicon chip, the waveguide and the optical fiber being optically coupled at an end face of the silicon chip.

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