JP2005331967A - Optical coupling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical coupling apparatus in which the modes of an optical semiconductor element and an optical waveguide, or the optical semiconductor element and an optical fiber are matched. <P>SOLUTION: The optical coupling apparatus has at least an optical waveguide and at least an optical component which are mounted facing to each other on a substrate, and a function that the expansion of a light distribution of a light beam propagating in either direction in the optical waveguide on a cross section perpendicular to an optical axis is smaller at the end face side facing to the optical component and becomes larger toward the opposite end face, or is larger at the end face side facing the optical component and becomes smaller toward the opposite end face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical device used for optical fiber communication or optical information processing, and more particularly, to optically couple an optical semiconductor element such as an optical semiconductor laser and an optical semiconductor element such as a single mode optical waveguide or an optical semiconductor laser and a single mode optical fiber. The present invention relates to a coupling device.

  In order to optically couple two or more single-mode optical components with high efficiency, it is necessary to perform mode matching between the two components and precisely align the optical axis. Here, the mode matching is to match the intensity distribution (also referred to as mode size) of light confined in two single-mode optical components to be optically coupled to each other between the two optical components. Conventional techniques for mode matching between two parts and precise optical axis alignment include those shown in FIGS. 18 to 27, for example.

  FIG. 18 illustrates an optical semiconductor device 200 such as a semiconductor laser and an optical fiber 3 that are optically coupled using lenses 41 and 42. A light beam is collimated by a first lens 41 and converged by a second lens 42. Are optically coupled. By using two lenses, the spot size (1.2 μm × 1.7 μm to 2.1 μm × 3.2 μm) of the light beam output from the optical semiconductor device 200 such as a semiconductor laser is expanded to about 4 to 6 times, and the optical fiber. It matches the mode size of 3 (about 10 μm). A high coupling efficiency can be obtained by matching the modes of the optical semiconductor device and the optical fiber with the first lens 41 and the second lens 42.

  Further, as shown in FIG. 19 (a) or FIG. 19 (b), an optical semiconductor device 200 such as a semiconductor laser is provided with a sealing window 607 interposed between the first lens 41 and the second lens. Hermetic sealing is performed to prevent the optical semiconductor device 200 from being deteriorated by moisture, oxidation, or the like. Here, 600 is a hermetically sealed portion, 601 is a base, 603 is a semiconductor laser submount, 606 is a sealing spacer, 31 is a ferrule for holding the optical fiber 3, and 32 is via a second lens 42. This is a fiber coupling portion that couples the optical fiber 3 and the first lens 41.

  Next, FIG. 20 shows an optical fiber 3A whose tip is processed into a lens shape (the one shown in FIG. 20 is called a tapered tip spherical fiber. In addition, a method for forming a lens-like one at the tip by melting the tip of the optical fiber Are also used for optical coupling. When the tip of the optical fiber is made thin and spherical, the size of the light beam at the incident end of the optical fiber is reduced. As a result, the mode sizes of the optical fiber and the semiconductor laser are matched to improve the coupling efficiency.

  FIG. 21 shows an example in which the semiconductor laser is hermetically sealed in the coupling system illustrated in FIG. An optical fiber 3A having a metal coating (not shown) on its surface by vacuum deposition or the like is fixed to the block 610 using solder 611 or the like, and a flange of a member 32 for holding the ferrule 31 holding the optical fiber 3A; Then, the boundary portion with the sealing portion 600 is welded and hermetically sealed.

  Here, in the case of FIG. 18, FIG. 19 (a) and FIG. 19 (b), the optical semiconductor device 200 such as a semiconductor laser, the two lenses 41 and 42 and the optical fiber 3 are shown in FIG. 20 and FIG. Requires an extremely precise alignment between the optical semiconductor device 200 such as a semiconductor laser and the optical fiber 3A. At that time, high accuracy is required for the alignment. Therefore, for example, when the optical semiconductor device 200 is a semiconductor laser, the semiconductor laser emits light, the intensity of the light coupled to the optical fiber 3 or 3A is measured, and the position is aligned and fixed so as to maximize it. To do.

  FIG. 22 is an example of simplifying the alignment of an optical semiconductor device such as a semiconductor laser and an optical fiber. For example, a silicon substrate or the like in which a V-groove 181, a bonding pad (for example, 102 illustrated in FIG. 28) and an alignment mark (for example, 107 illustrated in FIG. 28) are formed on the surface of the mounting substrate 180 by a photolithography process. The optical fiber 3 is guided and positioned by the V groove 181 on the substrate 180. On the other hand, in the optical semiconductor device 200 such as a semiconductor laser, a mark (for example, 204 illustrated in FIG. 28) corresponding to the alignment mark on the substrate and a bonding pattern (for example, illustrated in FIG. 28) corresponding to the bonding pad on the substrate 180. 202, 203) are used. Then, an alignment mark (for example, 204 illustrated in FIG. 28) of the optical semiconductor device 200 such as a semiconductor laser is aligned with an alignment mark (for example, 107 illustrated in FIG. 28) on the substrate using a precise fine movement device. And bonding (see, for example, Non-Patent Document 1 and Non-Patent Document 2).

  By doing so, the optical semiconductor device 200 such as a semiconductor laser and the optical fiber 3 are aligned. Here, the symbol 1B is attached to the optical coupling device illustrated in FIG. 22, and this is referred to in the following description.

  In the conventional example shown in FIG. 22, when the optical semiconductor device 200 is a semiconductor laser, for example, as shown in FIG. 23, when a tapered tip spherical fiber 3A is used as an optical fiber, the modes of the optical fiber 3A and the semiconductor laser 200 Match the size and improve the coupling efficiency.

  FIG. 24 shows an example of hermetically sealing an optical semiconductor device such as a semiconductor laser in the coupled system as shown in FIG. 22 or FIG. Here, FIG. 24 (a) shows a configuration before airtight sealing, and FIG. 24 (b) shows a configuration after sealing.

  The hermetic sealing of the apparatus shown in FIG. 24 is performed as follows. First, an optical coupling device 1B in which an optical semiconductor device 200 such as a semiconductor laser and an optical fiber 3 are coupled is disposed on a base 700 having a projection frame 702 having a notch 703 in part (FIG. 24A). Next, an epoxy adhesive 705 is applied to the upper side and the periphery of the projection frame 702. Next, the lid 400 is covered, and the gap between the lid 400 and the base is filled with an adhesive 705 to hermetically seal (FIG. 24 (b)).

  Next, another conventional example will be described. FIG. 25 shows an example in which an optical waveguide is included in an optical component, and the optical waveguide is optically coupled to another optical component. FIG. 25 (a) is a perspective view, and FIG. 25 (b) is a front front view seen from the lower left direction of FIG. 25 (a). In this example, a protrusion 300A (hereinafter referred to as a “stand-off”) made of the same optical waveguide member as the optical waveguide 300 having a two-layer structure made up of a clad layer 301 and a core 302 is formed on the substrate 100 and cut into four corners. The optical semiconductor device 200 in which the notch 202 is formed is fitted into the standoff 300A for alignment.

  The optical waveguide 300 in this example is a multimode waveguide, and the thickness of the clad layer 301 is 50 μm or more. In the optical coupling device as shown in FIG. 25, there is a problem that it is difficult to accurately form the notches 202 at the four corners of the optical semiconductor device 200 such as a semiconductor laser.

  Next, when a single mode optical waveguide is used as the optical waveguide instead of the multimode waveguide as shown in FIG. 25, the optical waveguide as shown in FIG. 26 is used. 26, for example, a silicon substrate is used for the substrate 100, and quartz is used for the clad layer 301 and the core 302 of the waveguide 300 (the clad layer 301 in FIG. 26 covers the periphery of the core 302). Therefore, “cladding layer 301” is more suitable than “cladding layer 301”, but “cladding layer 301” is used to unify the terms.

  In this case, the relative refractive index difference between the core 302 and the cladding layer 301 [percentage obtained by dividing the relative refractive index difference between the refractive index of the core (refractive index n1) and the cladding (refractive index n2) by the refractive index of the cladding, that is, { (N2−n1) / n1} × 100] is 0.3% to 0.75% and the size of the core 302 is about 5 × 5 μm to 8 × 8 μm, a relatively high coupling efficiency is obtained when optically coupled to an optical fiber. It is done. In this case, the thickness of the clad layer between the substrate and the core (t in FIG. 26 (b)) is 30 μm or more.

  When the optical waveguide 300 and the optical semiconductor device 200 are coupled using the method shown in FIG. 26, the optical axis of the semiconductor laser 200 needs to be lifted when the optical semiconductor device 200 is a normal semiconductor laser. As a configuration for that purpose, a spacer 5 may be placed under the semiconductor laser 200 as shown in FIG.

As described above, in the past, mode matching with a lens and mode matching with an optical fiber whose tip was processed into a lens shape were performed, and precise alignment with a fine movement device in the case of an optical fiber (in the case of FIGS. 19 and 21) Or alignment of the optical fiber by the groove on the substrate (FIGS. 22 to 24), and alignment of the semiconductor laser by aligning the substrate and semiconductor laser marks using a fine movement device when the semiconductor laser is mounted on the substrate (FIG. 28). In the case of an optical waveguide, alignment by standoff and notch is performed, and it is necessary to use a spacer or the like to align the optical waveguide and the optical axis of the semiconductor laser.
IEEE TRANSACTIONS ON COMPONENTS, HYBRIDS, AND MANUFACTURING TECHNOLOGY, VOL.15, NO.6, p.944-955 (1992) Proceedings of the 1993 IEICE Autumn Meeting 4-266

  However, the conventional examples shown in FIGS. 18 to 24 have the following problems. First, in the case of FIGS. 18 to 21, it is necessary to align the optical semiconductor device 200 such as a semiconductor laser and the lenses 41 and 42 and the optical fiber 3 or the optical semiconductor device 200 and the optical fiber 3 very precisely. Therefore, it takes a lot of time to align the optical components. Further, since the optical semiconductor device 200 such as a semiconductor laser is in an active state (for example, causing the semiconductor laser to emit light) during alignment, the optical semiconductor device such as a semiconductor laser is deteriorated or destroyed due to an erroneous operation or the like. There is.

  Next, what is shown in FIGS. 22 to 24 has an advantage that there is no need to activate an optical semiconductor device such as a semiconductor laser. However, the tolerance for misalignment that maintains the optical coupling efficiency above a certain level (for example, 80% or more of the maximum value) (this tolerance on misalignment is called coupling tolerance) has a lens function at the tip as shown in FIG. When the optical fiber 3A is used, it is 0.5 μm or less, and even when the optical fiber 3 having a flat tip as shown in FIG. 22 is used, it is as small as ± 1 μm. Therefore, there is a problem that mechanical alignment is not easy. In particular, when bonding an optical semiconductor device 200 such as a semiconductor laser, there is a problem that it is difficult to make the axial deviation between the groove 181 that guides the optical fiber 3 and the optical semiconductor device 200 such as a semiconductor laser below a predetermined value. is there. Further, in the case of FIG. 22, there is a problem that the mode mismatch between the optical semiconductor device 200 such as a semiconductor laser and the optical fiber 3 becomes large and the coupling loss becomes large (the coupling loss becomes about 7 dB at the minimum).

  In the optical coupling between the optical waveguide 300 in FIG. 25 and the optical semiconductor device 200 such as a semiconductor laser, there is a problem that it is not always easy to form the notches 202 at the four corners of the optical semiconductor device 200 with high accuracy.

  Next, as shown in FIG. 26, when using a substrate 100 having a refractive index higher than that of the waveguide material (specifically, quartz) such as a silicon substrate, in order to reduce light emission to the substrate 100. The cladding layer 301 below the core 302 needs to be thick. For example, in the case of the exemplified structure (relative refractive index difference is 0.3% to 0.75%, core size is 5 × 5 μm to 8 × 8 μm), the lower clad layer must be 30 μm or more as described above. The same applies to the case where an optical waveguide as shown in FIG. 25 is used. Therefore, in the optical coupling between the optical waveguide and the semiconductor laser illustrated in FIG. 25 and FIG. 26, there is a problem that it is difficult to match the heights of the optical axes of the two. To clarify this, FIG. 28 shows an example of a conventional semiconductor laser bonding method, and FIG. 29 shows an example of the configuration and dimensions of a semiconductor laser when it is flip-chip bonded to a bonding pad on a substrate. The optical axis height of the semiconductor laser will be specifically described.

  FIG. 28 illustrates only the main part of the example in which the semiconductor laser 200 is mounted on the substrate 100. FIG. 28 (a) is a perspective view showing a process of placement, and FIG. 28 (b) is a front view after placement. As illustrated in FIG. 28A, a bonding pad 205 is formed on the lower surface of the semiconductor laser 200, and a bonding flux (gold-tin eutectic alloy, etc.) 203 is deposited on the formed bonding pad 205. Then, the bonding pad 205 is placed on the bonding pad 102 separately formed on the substrate with the bonding material sandwiched therebetween, and then heated and cooled, so that the semiconductor laser 200 becomes the substrate 100 as shown in FIG. Glued and fixed on top.

  Next, FIG. 29 illustrates a detailed layer structure of the silicon substrate 100 and the semiconductor laser 200 to be bonded by the method of FIG. For example, FIG. 28 (b) is an enlarged view of the vicinity of the bonding pad 102, the bonding pad 205, and the bonding flux 203 at the center. Using FIG. 29, specific dimensions of each part are obtained. For example, the thickness of the wiring pattern 102A is 0.3 μm, the thickness of the insulating film 108 is 0.3 μm, the thickness of the bonding pad 102 is 0.35 μm, the thickness of the bonding material 203 is 2 to 6 μm, and the thickness of the bonding pad 205 The thickness of the insulating film 26 is 0.3 μm, the thickness of the cladding layer 231 is 1.5 μm, and the thickness of the active region layer 201 (described as an active layer in the figure) is 0.14 μm. In this case, the height from the surface of the thermal oxide film 101 of the substrate to the center of the active layer 201 of the semiconductor laser is 5.32 to 9.32 μm.

  As described above, the height of the optical axis (5.32 to 9.32 μm) of the semiconductor laser 200 is extremely lower than the height (about 33 μm) of the center of the core of the optical waveguide. Therefore, in the conventional example of FIGS. 25 and 26, when the semiconductor laser 200 is directly bonded and optically coupled to the substrate 100, the optical axis of the semiconductor laser 200 and the optical axis of the optical waveguide 300 are made to coincide with each other. This creates a problem that makes it difficult.

  Here, it is conceivable that the optical axis of the semiconductor laser 200 and the optical axis of the optical waveguide 300 are made to coincide with each other by placing the spacer 5 under the semiconductor laser as shown in FIG. However, in this case, there is a problem that the positional deviation due to the processing error between the spacer 5 and the optical waveguide 300 becomes large due to the high optical axis of the optical waveguide 300. That is, since the magnitude of the positional shift due to the processing error between the spacer 5 and the optical waveguide 300 is proportional to the height of both optical axes, the optical axis height t of the optical waveguide 300 increases as shown in FIG. The error dimension becomes large, causing a problem of large deviation. Specifically, if the processing error of the spacer 5 and the processing error of the optical waveguide 300 are both ± 5%, an error of ± 1.5 μm is generated when the optical axis height is 30 μm, and the maximum is ± 3 μm in total. Misalignment occurs. Due to this large shift, there is a problem that many defective products in which a desired coupling efficiency cannot be obtained occur in an optical coupling device that couples a normal semiconductor laser and a single mode optical waveguide.

  As described above, in the conventional examples illustrated in FIG. 18 to FIG. 21, mode matching is performed by an optical fiber having a lens or a tip processed into a lens shape. However, the optical semiconductor element is activated and the optical output is measured. However, in the conventional examples illustrated in FIG. 22, FIG. 23, FIG. 24, FIG. 25, FIG. 26 and FIG. 28, the optical fiber is aligned by the grooves on the substrate. Aligning the optical waveguide by laser and photolithography, and aligning the semiconductor laser by aligning the mark of the substrate and the semiconductor laser using a fine movement device (Figure 22, Figure 23, Figure 24, Figure 26, Figure 28) Since the alignment method using the standoff and the notch (FIG. 25) is used, there is no need to activate the optical semiconductor element at the time of alignment. However, the conventional examples illustrated in FIGS. 22 to 26 and FIG. 28 have a problem that the optical coupling efficiency is likely to be lowered because the positional deviation at the time of bonding the optical semiconductor element tends to be large. In the prior art illustrated in FIG. 22, there is a problem that it is difficult to match the height of the optical axis of the optical semiconductor element and the optical waveguide. In the prior art illustrated in FIG. 22, FIG. 24, FIG. 26, and FIG. There is a problem that mode mismatch occurs between the semiconductor laser and the optical fiber or between the semiconductor laser and the optical waveguide.

  Accordingly, it is an object of the present invention to solve the problems of the above-described conventional optical coupling device, and in particular, when an attempt is made to simplify alignment during optical coupling, an optical semiconductor element and an optical waveguide or an optical semiconductor element. The problem is to make it difficult to match the mode of the optical fiber with the mode of the optical fiber.

  The gist of the configuration and operation of the means for solving the above problems is as follows.

  Means 1 to 4 use optical waveguides in which the spot sizes of the light beams at both ends of the optical waveguide coincide with the optical components coupled at both ends, and improve the coupling efficiency with the optical components at both ends or expand the coupling tolerance. Is. The means 1 to means 4 will be described below.

  First, as shown in FIGS. 8 (a), 9 (c), 10, 11, 13, 13, 15 (b), 16, and 17, the means 1 is connected to the optical coupling device at the incident end. An optical waveguide is used in which the intensity distribution of light guided at the incident end and the outgoing end changes when light propagates from the outgoing end to the outgoing end.

  For example, as illustrated in FIG. 9C, an optical waveguide 300 according to this means is interposed between the semiconductor laser 200 and the optical fiber 3, and the shape of the spot on the side optically coupled to the semiconductor laser 200 is the same as that of the semiconductor laser 200. If the shape of the spot on the side optically coupled to the optical fiber 3 is the same as that of the optical fiber 3, optical coupling can be achieved with high coupling efficiency.

  Furthermore, when the spot size at the exit end of the optical waveguide 300 on the side facing the optical fiber is increased by the optical waveguide of this means, the coupling tolerance between the optical waveguide 300 and the optical fiber 3 is also increased. For example, the coupling tolerance between the optical waveguide 300 and the optical fiber 3 is increased by integrating and mounting the semiconductor laser 200 and the optical waveguide 300 as illustrated in FIG. 9C. In the production of an optical coupling device that performs optical coupling and assembly by positioning, the effect of simplifying the alignment of the fibers is produced.

  Further, in FIG. 9C, if the refractive index difference between the cladding and the sub-core is reduced and the cross-section of the sub-core is increased, the spot size of the optical waveguide 300 on the side optically coupled to the optical fiber 3 is increased. It becomes possible. For example, the graph (a) in FIG. 2 shows how the spot size of light guided to the waveguide changes when the relative refractive index difference between the core and cladding (refractive index 1.55) of the slab waveguide as shown in FIG. This is an example of how it changes. Since the core thickness must be changed when the relative refractive index difference between the core and the clad is changed, FIG. 2 also shows the core thickness (graph (b)).

  An example of a specific spot size in the case of the optical waveguide having the slab structure of FIG. 1 is about 11 μm when the relative refractive index difference is 0.2% and the core thickness is 7.9 μm. When an optical fiber having a partially expanded core (for example, described in Technical Digest of The Second Optoelectronics conference, 3C2-2, 1988, etc., hereinafter referred to as “TEC fiber”) is coupled to such an optical waveguide. The coupling tolerance between the optical waveguide and the optical fiber is further increased. For example, using a TEC fiber with a guided light spot size expanded to 18 μm, a maximum coupling efficiency of about 91% and a coupling tolerance of ± 3.6 μm (when the coupling efficiency is 80% or more of the maximum value) can be obtained. As a result, optical coupling between the optical waveguide and the optical fiber is facilitated.

  Furthermore, when this means is used, there is an effect that the loss when the core of the optical waveguide is bent is reduced. Next, this will be described. If the core of the optical waveguide is curved, when the radius of curvature becomes small, light is emitted to the outside and lost. The ease with which this radiation occurs depends on the structure of the optical waveguide.

  The ratio of the light confined in the core between the core and the clad layer of the optical waveguide (the ratio of the integral value of the electric field distribution distributed in the core to the total integral value) is expressed as “the intensity of light confinement” In other words, the stronger the light confinement, the smaller the loss due to bending of the waveguide. Then, in a waveguide where the spot size of the waveguide changes, as in the case of this means, light confinement becomes strong at a spot size that is small. Therefore, this means is used in an optical waveguide including a portion that is optically coupled to another optical component and a bent portion, and a portion that is optically coupled to another optical component is reduced by relatively reducing the spot size of the bent portion. If the spot size is increased, the radiation loss at the bent portion is reduced, or the radius of curvature at the bent portion is reduced (and thus miniaturization is possible), and the optical coupling with other optical components is easy. A waveguide is realized.

  The means 2 can be applied to the optical coupling device with a relatively high refractive index as illustrated in FIGS. 8, 9 (c), 10, 11, 13, 15 (b), 16, and 17. Thus, the sub-core 302B having a relatively low refractive index surrounds the periphery of the main core 302A having a portion in which the cross-sectional area or the shape of the outer contour thereof gradually changes from the middle as it advances in the optical axis direction. An optical waveguide having a composite core with a structure is used.

  The optical waveguide used in this means is an optical waveguide having a core in which the main core 302A is surrounded by the sub-core 302B, as illustrated in FIG. 8A, for example. On the side, the width of the main core 302A is wide and the width gradually decreases from the middle, and eventually the main core 302A disappears. As illustrated in the electric field distribution (2) of FIG. 8D, in the portion having the main core 302A having a wide right side, an optical waveguide having a main core as a core and a sub-core as a clad is formed. In FIG. 8D, (1) and (2) show the electric field distribution). Therefore, the spot diameter becomes small. When the main core 302A disappears, light is confined only by the sub-core 302B, so that the spot diameter increases as shown in the electric field distribution (1) on the left side of FIG. 8 (d). In the intermediate portion, the spot diameter gradually changes by gradually changing the shape of the core as shown in FIG. By using this means, the optical waveguide described in means 1 is realized.

  As illustrated in FIGS. 11, 12, 16 (a), and 16 (b), the means 3 gradually moves along the sub-core 302B in the optical axis direction in the optical waveguide of the means 2. The cross-sectional area or the contour thereof is changed.

  The optical waveguide in FIG. 11 (a) includes a region in which the width of the sub-core 302B gradually increases from the upper right to the lower left of the optical waveguide. The optical waveguide in FIG. From the left to the lower left, the sub-core 302B includes a region where the width gradually decreases.

  FIG. 12 shows the relationship between the horizontal electric field distribution of the light guided by the upper right end portion of the optical waveguide shown in FIGS. 11 (a) and 11 (b) and the width of the sub-core. Here, Fig. 12 (a) illustrates the cross section of the optical waveguide and the intensity distribution (1) of the electric field guided by it, and Fig. 12 (b) shows the width Ws and refractive index of the sub-core 302B in Fig. 12 (a). It illustrates the change in the width We (where We is the spot size) of the electric field intensity distribution (1) when n2 changes.

  As illustrated in FIG. 12B, when the width of the sub-core is widened, the electric field distribution is widened, and when the width of the sub-core is narrowed, the electric field distribution is narrowed. Therefore, the width of the sub-core can be adjusted to adjust the shape of the electric field distribution, and mode matching with other optical components coupled to the optical waveguide can be achieved.

  Further, when the refractive index of the sub-core is reduced, the electric field distribution becomes wide, and when the refractive index of the sub-core is increased, the electric field distribution becomes narrow. Therefore, the refractive index of the sub-core can be adjusted to adjust the shape of the electric field distribution, and mode matching with other optical components coupled to the optical waveguide can be achieved. Thus, by using this means, the optical waveguide described in means 2 is improved, and the adjustment range of the electric field distribution is expanded.

  Next, as illustrated in FIGS. 10 and 16 (c), the means 4 has a main structure in which its cross-sectional area or its shape gradually changes from the middle as it proceeds in the optical axis direction with a relatively high refractive index. The core of the optical waveguide is a combination of a main core and a sub core having a structure in which the core 302A is sandwiched between two sub-cores 302B having a relatively low refractive index in the vertical and horizontal directions. 10 and 16 (c) only illustrate the case where the main core 302A is sandwiched from the upper and lower directions by the secondary core 302B. However, if the vertical and horizontal relationships are interchanged, the secondary core is the main core. The optical waveguide having the same function is also sandwiched between the left and right directions.

  As illustrated in FIG. 12 (b), in the optical waveguide having the configuration of FIG. 12 (a), when the width of the sub-core is changed, the spot size is the largest when the width of the sub-core and the main core is the same. Get smaller. Therefore, the optical waveguide according to this means is suitable for mode matching with an optical component having a small spot diameter.

  Next, as illustrated in FIG. 13, the means 5 uses any one of the optical waveguides of means 2 to means 4 having the main core 302A and the sub-core 302B in at least a curved portion of the curved optical waveguide 300. Is.

  Since light has a property of being confined in a portion having a high refractive index such as the core of the optical waveguide, even if the optical waveguide is bent, it propagates along the optical waveguide. However, since light naturally travels straight, if the light confinement is weak and the radius of curvature of the bend is small, the light will jump out of the optical waveguide at the bend (hereinafter referred to as light emission by the bend). ). The strength of light confinement in the waveguide depends on the structure of the optical waveguide. Generally, when the core size is constant, the confinement becomes stronger as the difference in refractive index between the core and the clad increases. In the optical waveguide as shown in FIG. 8, light is confined in both the main core 302A and the sub-core 302B in a part of the main core 302A. Therefore, light confinement in a part of the main core 302A is confined in the main core 302A. It will be stronger than the missing part. Therefore, as illustrated in FIG. 13, if the main core 302A and the sub-core 302B are formed at the bent portion of the waveguide, the light confinement at the bent portion is stronger than the other portions. Therefore, radiation at the bent portion is less likely to occur. As a result, the radius of curvature of the bending can be reduced, and the optical waveguide becomes smaller.

  Next, as illustrated in FIG. 14, the means 6 forms a core 302 having a relatively large cross-sectional area at least in a curved portion of a curved optical waveguide. The strength of light confinement in the optical waveguide depends on the structure of the optical waveguide. Generally, when the core size is constant, the greater the difference in refractive index between the core and the clad, the stronger the confinement. When the difference in the refractive index of the clad is constant, the confinement becomes stronger as the cross-sectional area of the core is larger.

  Further, the spot size of light guided by the optical waveguide becomes larger as the cross-sectional area of the core becomes smaller when the relative refractive index difference between the core and the clad is constant. Therefore, as illustrated in FIG. 14, if the cross-sectional area of the core 302 at the end of the optical waveguide is reduced, the spot size is increased and the coupling with an optical fiber or the like is facilitated. On the other hand, when the cross-sectional area of the core 302 is increased at the bent portion of the waveguide, the light confinement becomes relatively strong. Therefore, radiation at the bent portion is less likely to occur. As a result, the radius of curvature of the bending can be reduced, and the optical waveguide can be reduced in size.

  Next, the means 7 is the light guide of any one of means 1 to means 5 as exemplified in FIGS. 8, 9 (c), 10, 11, 13, 15 (b), 16, and 17. Regarding the waveguide, at least one of the layers constituting the optical waveguide is composed of an organic substance.

  In the case of this optical waveguide, an organic material is used for the under cladding layer 301A, the main core 302A, the sub core 302B, and the over cladding layer 301B. In this way, it is possible to easily form a desired optical waveguide simply by etching the main core 302A and the sub-core 302B with oxygen plasma into a predetermined shape and applying the organic substance 301B again.

  Next, the means 8 is an optical waveguide according to any one of means 1 to 13 as exemplified in FIGS. 8, 9 (c), 10, 11, 13, 15 (b), 16, and 17. With respect to the above, at least an inorganic material is used for the main core 302A and an organic material is used for the sub-core 302B.

  That is, in the optical waveguide illustrated in these drawings, if the main core 302A is a silicon oxide film or silicon nitride film formed by plasma CVD, for example, a very thin core can be formed. Furthermore, the refractive index can be controlled in the range of 1.6 to 1.9.

  For example, when polyimide or the like is used for the main core 302A and the sub core 302B, the refractive index of polyimide is in the range of 1.5 to 1.6, so the relative refractive index difference between the main core 302A and the sub core 302B is about 3.2% or less. . When the relative refractive index difference is small, confinement becomes weaker as the core becomes thinner. Therefore, even if the core size is reduced, the spot size is not reduced. On the other hand, when polyimide is used for the sub-core 302B and a silicon oxide film or silicon nitride film is used for the main core 302A, the relative refractive index difference can be increased up to about 20%. As a result, an optical waveguide having a relatively small mode size can be formed.

  FIG. 3 illustrates the spot size when the relative refractive index of the clad layer 301 and the secondary core 302B is 0.5%, the thickness of the secondary core is 5 μm, and the refractive index of the primary core 302A is changed between 1.6 and 1.9. It is. In the graph of FIG. 3, curve (a) shows the case where the thickness of the main core is 0.2 μm, and curve (b) shows the case where the thickness of the main core is 0.5 μm.

  Thus, by using an inorganic material for the main core and making the main core thin with a high refractive index, an optical waveguide with a small mode size can be formed, and mode matching between the optical waveguide and the semiconductor laser becomes easy. For example, when the spot size of the optical waveguide is selected within the range surrounded by the line A in FIG. 3, the coupling loss due to mode mismatch when optically coupled to the semiconductor laser can be made extremely small.

  Next, as illustrated in FIGS. 6, 7, 15, and 16, the means 9 is arranged between the organic layer and the organic layer with respect to the optical waveguide by either the means 7 or 8. A structure having an inorganic thin film 311 is employed.

  In the examples of FIGS. 6, 7, 15, and 16, a thin film 311 made of an inorganic material is provided between the core 302 and the under cladding layer 301A. When an organic substance is used for the core 302, the core is processed by plasma etching. As illustrated in FIGS. 6, 7, 15, and 16, an inorganic material thin film is formed between the core 302 and the undercladding layer 301A. When 311 is formed, etching can be stopped at the thin film 311 when the core 302 is processed into a rectangle by oxygen plasma etching. As a result, the management of the etching process at the time of processing the core is facilitated, and the effect of ensuring the etching is produced.

  As described above, according to the present invention, the core of the optical waveguide is composed of the main core, the sub-core having a lower refractive index than the main core, the structure surrounding the sub-core around the main core, and in the light traveling direction. The spot diameter of the light propagating through the core is changed by forming the cross-sectional area of the main core gradually smaller along the direction, or by changing the cross-sectional area of the core of the optical waveguide in the light propagation direction. If the semiconductor laser is connected to the side where the cross-sectional area of the main core is large and the optical fiber is connected to the small side, the semiconductor laser and the optical fiber can be optically coupled with a high degree of coupling. There is an effect that the optical coupling device can be miniaturized because it can be bent with a small radius of curvature.

  Hereinafter, the details of the present invention will be described with reference to the drawings.

  FIGS. 8, 10, and 11 show examples of a single optical waveguide in which the spot size of light or the strength of confinement varies depending on the location as light propagates through the optical waveguide.

  FIG. 8 shows an example 1 of an optical waveguide whose light spot size changes as it propagates. A core 302 having a structure in which a main core 302A having a relatively high refractive index is surrounded by a sub-core 302B having a relatively low refractive index. An example of the optical waveguide 300 is shown. 8 (a) is a perspective view thereof, FIG. 8 (b) is a plan view seen from the upper side of FIG. 8 (a), FIG. 8 (c) is a view on the line X1-X1 ′ of FIG. The refractive index profile on X2-X2 ′, FIG. 8 (d) is a side view cross section viewed from the lower right direction, FIG. 8 (e) is on the lines Y1-Y1 ′ and Y2-Y2 in FIG. 8 (d). 'Shows the refractive index distribution above. 8D is a side sectional view taken along the center of the optical axis, the dotted line in FIG. 8C is the refractive index distribution on X1-X1 ′, and the solid line in FIG. 8C is X2-X2. The refractive index distribution on ', the dotted line in Fig. 8 (e) is the refractive index distribution on Y1-Y1', the solid line in Fig. 8 (e) is the refractive index distribution on Y2-Y2 ', the line in Fig. 8 (d) (1) and (2) are electric field distributions of light guided by the waveguide.

  The optical waveguide 300 of the present embodiment has a main core 302A at one end, and has a main core 302A having a constant width in a certain section as it advances along the optical axis therefrom, and then the main core 302A. Gradually decreases, and then the main core 302A disappears. Specifically, the refractive index of the clad layer 301 is 1.55, the relative refractive index difference between the clad layer 301 and the sub-core 302B is 0.5%, the refractive index of the main core 302A is 1.6, and the external dimension of the cross-section of the sub-core 302B is 6 μm × At the end on the side including the main core 302A, the thickness of the main core 302A is 0.8 μm and the width is 3 μm. Also, the cladding layer 301, the sub-core 302B, and the main core 302A are all polyimide.

  In the optical waveguide 300 having such a configuration, as shown in (1) and (2) of FIG. 8 (d), the main core 302A is used as a core and the sub-core 302B is used as a clad in a portion where the main core 302A is present. A simple waveguide is formed. Therefore, the spot size is relatively small on the side where the main core 302A is present, and the spot size is relatively large on the side where the main core 302A is not present.

  Specifically, the spot size of the light guided by the waveguide on the side having the main core 302A is about 3.1 μm (vertical) × 5.5 μm (horizontal), and the spot size of the waveguide on the side without the main core 302A The diameter is about 6.7 μm.

  The spot diameter on the side having the main core 302A of the optical waveguide 300 according to this embodiment is substantially equal to the spot size of the semiconductor laser 200 used in the embodiment of FIG. Specifically, the spot size of the semiconductor laser 200 used in the embodiment of FIG. 4 is 3 μm × 6.8 μm. Therefore, for example, when the optical waveguide 300 according to this embodiment is used for the optical waveguide 300 of the embodiment of FIG. 4 and the side having the main core 302A is opposed to the semiconductor laser 200, high coupling efficiency can be obtained.

  Furthermore, the optical waveguide on the side without the main core 302A and the optical fiber are coupled with a relatively high efficiency. Therefore, for example, when the optical waveguide of this embodiment is used as the optical waveguide of the optical coupling device illustrated in FIGS. 4 and 5, an optical coupling device that is coupled with high efficiency to both the semiconductor laser and the optical waveguide is realized.

  Specific examples of the coupling efficiency in the case of the coupling system as shown in FIG. 9 are given below. 9A shows a case where the optical fiber 3 is directly coupled to the semiconductor laser 200, and FIG. 9B shows a case where the semiconductor laser 200 and the optical fiber 3 are coupled via the optical waveguide 300 having no main core 302A. 9 (c) shows a case where the semiconductor laser 200 and the optical fiber 3 are coupled via the optical waveguide of this embodiment (the embodiment of FIG. 8).

  In the embodiment described above, when the maximum optical coupling efficiency between the semiconductor laser 200 and the optical fiber 3 is obtained by paying attention only to the direction perpendicular to the junction of the semiconductor laser 200, the case of FIG. The case of FIG. 9B is about 77%, and the case of FIG. 9C is about 95%. As described above, when this embodiment is used, an optical coupling device with high coupling efficiency can be realized relatively easily.

  The optical waveguide in which the clad layer 301, the sub-core 302B, and the main core 302A are polyimide has been described above. However, these may be inorganic materials, or a mixture of organic material layers and inorganic material layers. May be.

  Therefore, for example, an example in which polyimide is used for the clad layer 301 and the sub-core 302B and a silicon oxide film or silicon nitride film is used for the main core 302A will be described.

  The optical waveguide of such an embodiment has the same configuration as that shown in FIG. 8, for example, a silicon nitride film is formed by plasma CVD, and this may be used as the main core 302A. Specifically, the refractive index of the cladding layer 301 is 1.55, the relative refractive index difference between the cladding layer 301 and the secondary core 302B is 0.5%, the refractive index of the primary core 302A is 1.7, and the external dimension of the cross-section of the secondary core 302B is 6 μm. × 6 μm At the end including the main core 302A, the thickness of the main core 302A is 0.19 μm and the width is 4.55 μm.

  The spot size on the side of the optical waveguide having the main core 302A is 3 μm × 5.7 μm. For example, when such an optical waveguide is used for the optical waveguide 300 in the embodiment of FIG. 4 and the side having the main core 302A of the optical waveguide is opposed to the semiconductor laser 200, optical coupling is performed with 99% efficiency only in the vertical direction. To do. As described above, when this embodiment is used, it becomes easy to make the spot size in the vertical direction coincide with that of the semiconductor laser and to improve the coupling efficiency. As a result, the coupling efficiency is improved.

  Next, an example in which the spot size of light guided by the optical waveguide according to the present embodiment is greatly changed will be described with reference to FIG. FIG. 3 illustrates the spot size when the relative refractive index of the clad layer 301 and the secondary core 302B is 0.5%, the thickness of the secondary core 302B is 5 μm, and the refractive index of the primary core 302A is changed between 1.6 and 1.9. Is. In the graph of FIG. 3, the curve (a) is when the thickness of the main core 302A is 0.2 μm, and the curve (b) is when the thickness of the main core 302A is 0.5 μm.

  FIG. 3 shows that the spot size can be changed between about 1 μm and 7 μm by changing the refractive index and thickness of the main core 302A. Furthermore, if the refractive index and the cross-sectional size of the sub-core 302B are changed in this embodiment, the spot size of light guided to the side where the main core 302A is not provided can be changed.

  For example, the graph (a) in FIG. 2 shows the spot size of light guided to the optical waveguide when the relative refractive index difference between the core 302 and the clad layer 301 (refractive index 1.55) of the slab waveguide as shown in FIG. 4 changes. It is an example of how the changes. Since the thickness of the core 302 must be changed when the relative refractive index difference between the core 302 and the clad layer 301 is changed, the thickness of the core 302 (graph (b)) is also shown in FIG.

  2 that the spot size can be changed between about 5 μm and 12 μm by changing the refractive index and thickness of the sub-core 302B. When the spot size of light guided by the optical waveguide is increased, the coupling efficiency between the optical waveguide and the optical fiber is improved, and the coupling tolerance is further increased.

  As described above, by using the present embodiment, by changing the size and refractive index of the main core 302A and the sub-core 302B, an optical waveguide capable of changing the spot size of the guided light over a wide range is realized. The As a result, an optical coupling structure having a high coupling efficiency and a large coupling tolerance can be formed.

  FIGS. 10 and 11 show examples 2, 3, and 4 of the optical waveguide in which the spot size of the light changes as it propagates, and the optical waveguide in which the cross-sectional shape of the sub-core 302B changes as it advances in the optical axis direction. An example is shown. Here, FIG. 10 shows that the width of the secondary core 302B on the side where the main core 302A is present in the embodiment of FIG. 8 is the same as that of the main core 302A (in the case of FIG. 8, compared to the main core 302A). The secondary core 302B is wider. In this case, as will be described later, the spot diameter in the lateral direction on the side having the main core 302A of the optical waveguide becomes smaller. Therefore, when this embodiment is used, for example, the coupling efficiency with a semiconductor laser having a smaller lateral spot diameter is improved.

  In FIG. 11 (a), the width of the secondary core 302B on the side where the main core 302A exists is wider than the width of the main core 302A and narrower than the width of the secondary core 302B on the opposite end (FIG. 11A). In the case of 8, the width of the secondary core 302B is constant). In this way, as will be described later, the lateral spot diameter on the side having the main core 302A of the optical waveguide is intermediate between the case of the embodiment of FIG. 8 and the embodiment of FIG.

  FIG. 11 (b) is such that the width of the secondary core 302B on the side where the main core 302A exists is relatively wide (in the case of FIG. 8, the width of the secondary core 302B is constant). . In this way, as will be described later, the lateral spot diameter on the side of the optical waveguide having the main core 302A is relatively large, so that the coupling efficiency with a semiconductor laser having a relatively large lateral spot diameter is obtained. Can be improved.

  FIG. 12 is for qualitatively explaining the effect of the embodiment of FIGS. FIG. 12 (a) is a sectional view of the optical waveguide. The refractive index of the cladding layer 301 is denoted by n1, the refractive index of the sub-core 302B is denoted by n2, and the refractive index of the main core 302A is denoted by n3. Further, the width of the main core 302A is indicated by Wm, and the difference between the width of the sub core 302B and the width of the main core 302A is indicated by Ws. Further, (1) shows the electric field intensity distribution of the light guided by this waveguide, and the spot size is indicated by We.

  FIG. 12 (b) qualitatively shows changes in We when Ws in FIG. 12 (a) and the refractive index n2 of the sub-core 302B change. The change of We when the horizontal axis is Ws and n2 is α, β, γ is shown.

  As illustrated in FIG. 12B, the spot size We increases as Ws increases. Further, as n2 increases, the spot size increases. Note that when Ws becomes smaller than a certain value, the opposite change occurs. Specifically, in the optical waveguide of the embodiment of FIG. 8 (the main core 302A is composed of a silicon nitride film having a refractive index of 1.7 and a thickness of 0.19 μm), for example, when Ws is 10 μm, the spot diameter in the lateral direction is It becomes 6.3μm (the spot diameter is 5.7μm when Ws is 0.7μm). Further, when Ws is sufficiently wide (for example, 20 μm) and Wm is narrowed to 1.5 μm, the lateral spot diameter is 7.2 μm.

  In the embodiment shown in FIG. 8, when the main core 302A is made of polyimide having a refractive index of 1.6 and a thickness of 0.8 μm, when Wm is 1.6 μm and Ws is 10 μm, the spot diameter in the lateral direction is 6.5 μm. become. Thus, by adjusting Ws and Wm, the spot size can be adjusted over a wide range. An optical coupling device having high coupling efficiency can be realized by adjusting the spot size of the optical waveguide and matching it with the semiconductor laser.

  FIG. 13 shows a single optical waveguide having a curved waveguide using a main core and a sub core, and shows an example in which the optical waveguide according to the embodiment of FIG. 8 is applied to a waveguide having a curvature. FIG. 13 (a) shows a configuration in which an optical waveguide has a bent portion and a main core 302A before and after the bent portion. FIG. 13 (b) shows a configuration in which the optical waveguide has a main core 302A from a bent portion to one end.

  In the waveguide according to the present embodiment, light is strongly confined in the bent portion, so that the loss is small even when the curvature of bending is relatively small. Further, in the case of FIG. 13 (b), the spot size of the light guided to the side where the main core 302A is provided becomes small, and the effect of improving the coupling efficiency with a semiconductor laser or the like is obtained.

  FIG. 14 shows an optical waveguide having a bent waveguide with the width of the core changed. In FIG. 14, the optical waveguide is divided into a bent portion and a periphery of a core 302 having a wide width before and after the bent portion. The structure is surrounded by. FIG. 14 (a) is a perspective view of the optical waveguide according to the present embodiment, and FIG. 14 (b) is a plan view of FIG. 14 (a) viewed from above.

  In the waveguide according to the present embodiment, light is strongly confined in the bent portion, so that the loss is small even when the curvature of bending is relatively small.

  15 and 16 show a configuration in which a silicon nitride film 311 formed by plasma CVD is arranged on the upper side of a clad layer 301A made of polyimide, and a core 302 and an over clad layer 301B are arranged thereon. It is. The thickness of the silicon nitride film 311 is 200 nm or less.

  15 (a) shows an example 1 having a single core 302. FIGS. 15 (b) and 16 (a) to 16 (c) show that the core 302 is composed of the main core 302A and the sub-core 302B. It is Example 2, Example 3, Example 4 and Example 5 comprised with a composite_body | complex. A silicon nitride film 311 formed by plasma CVD is disposed between the clad 301 and the core 302 of the waveguide corresponding to FIG. 8, FIG. 11 (a), FIG. 11 (b), and FIG. In this embodiment, after forming a layer to be the core 302, a mask is formed thereon, and then etching is performed with oxygen plasma to form the rectangular core 302. When this embodiment is used, when the core 302 is processed into a rectangle by oxygen plasma etching, the silicon nitride film 311 becomes an etching stop layer, which facilitates processing.

  FIG. 17 shows a core 302 formed of a composite of a main core 302A and a sub core 302B in a portion corresponding to the lower side of the metal ring 304 and an end facing the semiconductor laser 200 in the embodiment of FIG. A waveguide having Specifically, this waveguide has a refractive index of the cladding layer 301 of 1.55, a refractive index of the sub-core 302B of 1.558, a refractive index of the main core 302A of 1.6, and a cross-sectional dimension of the sub-core 302B of 6 μm × 6 μm, Furthermore, at the end including the main core 302A, the thickness of the main core 302A is 1 μm, the width of the main core 302A is 3 μm, and the thicknesses of the under cladding layer 301A and the over cladding layer 301B are 20 μm. By doing so, loss due to the presence of the metal ring 304 can be reduced.

The following additional notes are further disclosed with respect to the embodiment including the above examples.
(Additional remark 1) It has at least 1 optical waveguide and at least 1 optical component which were mounted facing each other on a board | substrate, and is perpendicular | vertical to the optical axis of the light beam which propagates this optical waveguide in either direction The spread of the light distribution of a simple cross section is small on the end surface facing the optical component and increases as the end surface opposite to the end surface is approached, or is large on the end surface facing the optical component. An optical coupling device having a function of decreasing as it approaches an end surface opposite to the side.
(Supplementary note 2) The optical waveguide has at least part of the periphery of the main core having a portion with a relatively high refractive index and a portion in which the cross-sectional area or cross-sectional shape of the optical waveguide changes as it advances in the optical axis direction. It has a composite core surrounded by a sub-core having a lower refractive index than the main core and a higher refractive index than the cladding layer of the optical waveguide, and the periphery of the composite core is surrounded by the cladding layer. The optical coupling device according to Supplementary Note 1, wherein:
(Supplementary note 3) The optical core has, at least in part, a main core having a portion having a relatively high refractive index and a portion in which a cross-sectional area or a cross-sectional shape of the optical waveguide changes as it proceeds in the optical axis direction. It has a composite core having a structure sandwiched between two upper and lower or left and right directions by a secondary core having a lower refractive index than the main core and a higher refractive index than the cladding layer of the optical waveguide, and further surrounding the composite core 2. The optical coupling device according to claim 1, wherein the optical coupling device has a structure surrounded by the cladding layer.
(Supplementary note 4) The optical coupling device according to supplementary note 2 or supplementary note 3, wherein the optical coupling device has a portion in which a cross-sectional area or a cross-sectional shape of the sub-core changes as it proceeds in the optical axis direction.
(Supplementary Note 5) An optical waveguide which is a first optical component having at least one bent portion and two straight portions extending from both ends of the bent portion on the substrate, and one end of the straight portion of the optical waveguide. And at least the bent portion of the optical waveguide has a refractive index lower than that of the main core and higher than that of the cladding layer. A composite core surrounded by a secondary core, and the periphery of the composite core is surrounded by the clad layer, and a main core is disposed on a part of at least one straight portion of the optical waveguide. An optical coupling device having an optical waveguide portion not included.
(Appendix 6) A structure in which a relatively high refractive index core is surrounded by a relatively low refractive index cladding layer on a substrate, and at least one bent portion and two straight portions extending from both ends of the bent portion An optical waveguide that is a first optical component comprising: a second optical component placed opposite to one end of the linear portion of the optical waveguide, and at least of the linear portion of the optical waveguide An optical coupling device characterized in that the cross-sectional area of the core in a region away from the bent portion is relatively smaller than that of the bent portion.
(Supplementary note 7) The optical coupling device according to any one of supplementary notes 2 to 5, wherein at least one of the cladding layer, the sub-core layer, and the main core layer of the optical waveguide is an organic layer.
(Supplementary note 8) The optical coupling device according to any one of supplementary notes 2 to 5, wherein an inorganic material is used for the main core layer of the optical waveguide and an organic material is used for the sub-core layer.
(Supplementary note 9) The optical coupling device according to any one of Supplementary note 7 and Supplementary note 8, wherein an inorganic material thin film is additionally laminated between layers of organic materials in contact with each other.

Cross-sectional view and refractive index profile of a three-layer slab structure optical waveguide with a buffer layer The figure which shows the spot size and core thickness of the light guided by the optical waveguide of FIG. The figure which shows the spot size of the light guided by the optical waveguide of FIG. The figure which shows the optical coupling device by an Example The figure which shows the optical coupling device of FIG. The figure which shows the optical coupling device which made the optical axis alignment of the height direction of the semiconductor laser and the optical waveguide easy The figure which shows the optical coupling device which made the optical axis alignment of the height direction of the semiconductor laser and the optical waveguide (each simple substance) easy Diagram showing a single optical waveguide whose spot size changes as it propagates Explanation of optical coupling when the output of a semiconductor laser is introduced directly into an optical fiber, when introduced through an optical waveguide, and when the optical waveguide changes the light spot size Diagram showing a single optical waveguide whose spot size changes as it propagates Diagram showing a single optical waveguide whose spot size changes as it propagates The figure which shows the change of the light spot size in FIG.10 and FIG.11. Diagram showing an optical waveguide including a single bent waveguide having a main core and a sub-core The figure which shows the optical waveguide which includes the curved waveguide where the width of the core is changed Diagram showing an optical waveguide in which a silicon nitride film is placed on a clad layer made of polyimide and a core is formed on the silicon nitride film Diagram showing an optical waveguide in which a silicon nitride film is placed on a clad layer made of polyimide and a core is formed on the silicon nitride film The figure which shows the Example which applied the composite core to the optical waveguide of the Example of FIG. The figure which shows the conventional optical coupling device which optically coupled the semiconductor laser and the optical fiber using the lens 1 is a view showing a conventional optical coupling device in which a hermetically sealed optical semiconductor laser and an optical fiber are optically coupled using a lens. The figure which shows the conventional optical coupling device which combined the semiconductor fiber and the optical fiber which processed the tip into the lens shape The figure which shows the conventional optical coupling device which airtightly sealed the semiconductor laser of FIG. The figure which shows the conventional optical coupling device which has the structure which simplifies the alignment of a semiconductor laser and an optical fiber 22 is a diagram showing a conventional optical coupling device that uses a tapered tip sphere fiber in the optical fiber of FIG. 22 to improve the coupling efficiency. The figure which shows the conventional optical coupling device which airtightly sealed the semiconductor laser of FIG. 22 or FIG. The figure which shows the conventional optical coupling device which applied the multimode optical waveguide The figure which shows the conventional optical coupling device which applied the single mode optical waveguide 1 shows a conventional optical coupling device in which a semiconductor laser and a single mode optical waveguide are coupled by raising the optical axis of the semiconductor laser. The figure which shows mounting explanatory drawing which shows mounting a semiconductor laser on a substrate using a mark using a fine movement device Conventional configuration diagram and dimensions of semiconductor laser and substrate for clip chip bonding of semiconductor laser

Explanation of symbols

1, 1A, 1B, 1C: optical coupling device,
2: Photodiode,
3, 3A: optical fiber,
5: Spacer
31: Ferrule,
32: Fiber coupling part,
41, 42: Lens,
100, 180: substrate,
101: Thermal oxide film
102, 205: Bonding pads,
102A, 103: wiring pattern,
106: depressions formed on the substrate,
107: mark for alignment,
108: Insulating film
181: groove for guiding the fiber,
200: an optical semiconductor device such as a semiconductor laser,
200X, 300X: Arrayed optical components,
201: active region,
202: Notch
203: Adhesive member for bonding,
204: Mark for alignment,
231: cladding layer,
300: Optical waveguide,
301: Clad layer of optical waveguide,
301A: Undercladding layer,
301B: Over clad layer,
302: core of optical waveguide,
302A: Main core,
302B: Deputy core,
303: hole,
304: Ring-shaped metal member,
311: inorganic thin film,
400: lid for hermetic sealing,
500: Electrical wiring member,
501, 503, 504: ring-shaped members,
502: Electrical wiring pattern,
600: A container for hermetically sealing an optical semiconductor element,
601: Base body
603: Submount,
606: Spacer,
607: sealing window,
610: Block,
611: Solder,
700: Base for hermetically sealing an optical semiconductor element,
702: protrusion frame,
703: the part where the protrusion 704 is cut out,
704: protrusion,
705: Adhesive.

Claims (5)

  Light having a cross section perpendicular to the optical axis of a light beam having at least one optical waveguide and at least one optical component mounted on the substrate in opposition to each other and propagating in either direction. The spread of the distribution is small on the end surface facing the optical component and increases as the end surface on the side opposite to the end surface is approached, or is large on the end surface facing the optical component, and is opposite to the end surface. An optical coupling device having a function of decreasing as it approaches an end face on the side.   At least part of the optical waveguide has a portion with a relatively high refractive index and a portion in which the cross-sectional area or cross-sectional shape of the optical waveguide changes as it advances in the optical axis direction. A composite core having a low refractive index and surrounded by a sub-core having a higher refractive index than that of the cladding layer of the optical waveguide, and the periphery of the composite core is surrounded by the cladding layer. The optical coupling device according to claim 1.   The optical waveguide has a main core having at least a portion with a relatively high refractive index and a portion whose cross-sectional area or cross-sectional shape changes as it advances in the optical axis direction. A composite core having a refractive index and a structure in which a secondary core having a refractive index higher than that of the clad layer of the optical waveguide is sandwiched between two directions of upper and lower sides or right and left is sandwiched. The optical coupling device according to claim 1, wherein the optical coupling device has a structure surrounded by   An optical waveguide, which is a first optical component having at least one bent portion and two straight portions extending from both ends of the bent portion, is placed on the substrate so as to face one end of the optical waveguide straight portion. A second optical component, and at least a bent portion of the optical waveguide has a lower refractive index around the main core having a relatively higher refractive index than the main core and a higher refractive index than the cladding layer. The composite core is surrounded by the clad layer, and at least one straight portion of the optical waveguide does not include the main core. An optical coupling device having an optical waveguide portion. The substrate has a structure in which a relatively high refractive index core is surrounded by a relatively low refractive index cladding layer, and has at least one bent portion and two straight portions extending from both ends of the bent portion. An optical waveguide that is a first optical component; and a second optical component that is placed opposite to one end of the linear portion of the optical waveguide, and at least from a bent portion of the linear portion of the optical waveguide. An optical coupling device, wherein a cross-sectional area of a core in a remote area is relatively smaller than a bent portion.

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